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-rw-r--r--Documentation/00-INDEX206
-rw-r--r--Documentation/ABI/README2
-rw-r--r--Documentation/ABI/stable/sysfs-devices14
-rw-r--r--Documentation/ABI/testing/sysfs-block42
-rw-r--r--Documentation/ABI/testing/sysfs-bus-fsl-mc21
-rw-r--r--Documentation/ABI/testing/sysfs-bus-iio18
-rw-r--r--Documentation/ABI/testing/sysfs-bus-iio-adc-envelope-detector36
-rw-r--r--Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8125
-rw-r--r--Documentation/ABI/testing/sysfs-bus-iio-cros-ec18
-rw-r--r--Documentation/ABI/testing/sysfs-bus-iio-dac-dpot-dac8
-rw-r--r--Documentation/ABI/testing/sysfs-bus-iio-light-isl2901819
-rw-r--r--Documentation/ABI/testing/sysfs-bus-iio-light-tsl258320
-rw-r--r--Documentation/ABI/testing/sysfs-bus-iio-potentiometer-mcp45318
-rw-r--r--Documentation/ABI/testing/sysfs-bus-pci7
-rw-r--r--Documentation/ABI/testing/sysfs-bus-vfio-mdev111
-rw-r--r--Documentation/ABI/testing/sysfs-class-fpga-bridge11
-rw-r--r--Documentation/ABI/testing/sysfs-class-led14
-rw-r--r--Documentation/ABI/testing/sysfs-class-mei16
-rw-r--r--Documentation/ABI/testing/sysfs-class-remoteproc50
-rw-r--r--Documentation/ABI/testing/sysfs-devices-deferred_probe12
-rw-r--r--Documentation/ABI/testing/sysfs-kernel-slab2
-rw-r--r--Documentation/ABI/testing/sysfs-platform-phy-rcar-gen3-usb215
-rw-r--r--Documentation/ABI/testing/sysfs-platform-sst-atom17
-rw-r--r--Documentation/ABI/testing/sysfs-power45
-rw-r--r--Documentation/BUG-HUNTING246
l---------[-rw-r--r--]Documentation/Changes486
-rw-r--r--Documentation/CodingStyle1063
-rw-r--r--Documentation/DocBook/Makefile7
-rw-r--r--Documentation/DocBook/alsa-driver-api.tmpl142
-rw-r--r--Documentation/DocBook/debugobjects.tmpl443
-rw-r--r--Documentation/DocBook/kernel-hacking.tmpl4
-rw-r--r--Documentation/DocBook/tracepoint.tmpl112
-rw-r--r--Documentation/DocBook/uio-howto.tmpl62
-rw-r--r--Documentation/DocBook/usb.tmpl992
-rw-r--r--Documentation/DocBook/writing-an-alsa-driver.tmpl6206
-rw-r--r--Documentation/IPMI.txt57
-rw-r--r--Documentation/Makefile.sphinx22
-rw-r--r--Documentation/RCU/Design/Requirements/Requirements.html25
-rw-r--r--Documentation/RCU/whatisRCU.txt2
-rw-r--r--Documentation/SubmittingPatches842
-rw-r--r--Documentation/VGA-softcursor.txt39
-rw-r--r--Documentation/acpi/DSD-properties-rules.txt97
-rw-r--r--Documentation/acpi/enumeration.txt9
-rw-r--r--Documentation/acpi/gpio-properties.txt62
-rw-r--r--Documentation/acpi/osi.txt187
-rw-r--r--Documentation/acpi/video_extension.txt2
-rw-r--r--Documentation/admin-guide/README.rst411
-rw-r--r--Documentation/admin-guide/binfmt-misc.rst151
-rw-r--r--Documentation/admin-guide/braille-console.rst38
-rw-r--r--Documentation/admin-guide/bug-bisect.rst76
-rw-r--r--Documentation/admin-guide/bug-hunting.rst369
-rw-r--r--Documentation/admin-guide/conf.py10
-rw-r--r--Documentation/admin-guide/devices.rst268
-rw-r--r--Documentation/admin-guide/devices.txt (renamed from Documentation/devices.txt)1176
-rw-r--r--Documentation/admin-guide/dynamic-debug-howto.rst353
-rw-r--r--Documentation/admin-guide/index.rst69
-rw-r--r--Documentation/admin-guide/init.rst (renamed from Documentation/init.txt)29
-rw-r--r--Documentation/admin-guide/initrd.rst (renamed from Documentation/initrd.txt)199
-rw-r--r--Documentation/admin-guide/java.rst (renamed from Documentation/java.txt)297
-rw-r--r--Documentation/admin-guide/kernel-parameters.rst209
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt (renamed from Documentation/kernel-parameters.txt)269
-rw-r--r--Documentation/admin-guide/md.rst (renamed from Documentation/md.txt)528
-rw-r--r--Documentation/admin-guide/module-signing.rst (renamed from Documentation/module-signing.txt)128
-rw-r--r--Documentation/admin-guide/mono.rst (renamed from Documentation/mono.txt)44
-rw-r--r--Documentation/admin-guide/parport.rst286
-rw-r--r--Documentation/admin-guide/ramoops.rst (renamed from Documentation/ramoops.txt)88
-rw-r--r--Documentation/admin-guide/ras.rst1190
-rw-r--r--Documentation/admin-guide/reporting-bugs.rst182
-rw-r--r--Documentation/admin-guide/security-bugs.rst (renamed from Documentation/SecurityBugs)14
-rw-r--r--Documentation/admin-guide/serial-console.rst (renamed from Documentation/serial-console.txt)68
-rw-r--r--Documentation/admin-guide/sysfs-rules.rst192
-rw-r--r--Documentation/admin-guide/sysrq.rst289
-rw-r--r--Documentation/admin-guide/tainted-kernels.rst59
-rw-r--r--Documentation/admin-guide/unicode.rst (renamed from Documentation/unicode.txt)24
-rw-r--r--Documentation/admin-guide/vga-softcursor.rst62
-rw-r--r--Documentation/arm/Booting2
-rw-r--r--Documentation/arm/stm32/overview.txt3
-rw-r--r--Documentation/arm/stm32/stm32f746-overview.txt34
-rw-r--r--Documentation/assoc_array.txt574
-rw-r--r--Documentation/bad_memory.txt45
-rw-r--r--Documentation/basic_profiling.txt56
-rw-r--r--Documentation/binfmt_misc.txt131
-rw-r--r--Documentation/block/biodoc.txt6
-rw-r--r--Documentation/block/cfq-iosched.txt32
-rw-r--r--Documentation/block/null_blk.txt2
-rw-r--r--Documentation/block/queue-sysfs.txt23
-rw-r--r--Documentation/blockdev/cciss.txt2
-rw-r--r--Documentation/blockdev/ramdisk.txt2
-rw-r--r--Documentation/braille-console.txt34
-rw-r--r--Documentation/cgroup-v1/00-INDEX2
-rw-r--r--Documentation/circular-buffers.txt4
-rw-r--r--Documentation/conf.py22
-rw-r--r--Documentation/core-api/assoc_array.rst551
-rw-r--r--Documentation/core-api/atomic_ops.rst (renamed from Documentation/atomic_ops.txt)340
-rw-r--r--Documentation/core-api/conf.py10
-rw-r--r--Documentation/core-api/debug-objects.rst310
-rw-r--r--Documentation/core-api/index.rst33
-rw-r--r--Documentation/core-api/local_ops.rst206
-rw-r--r--Documentation/core-api/tracepoint.rst55
-rw-r--r--Documentation/core-api/workqueue.rst (renamed from Documentation/workqueue.txt)260
-rw-r--r--Documentation/cpu-freq/cpufreq-stats.txt6
-rw-r--r--Documentation/cpu-freq/intel-pstate.txt54
-rw-r--r--Documentation/cpu-hotplug.txt32
-rw-r--r--Documentation/crypto/api-intro.txt5
-rw-r--r--Documentation/dev-tools/conf.py10
-rw-r--r--Documentation/dev-tools/gcov.rst8
-rw-r--r--Documentation/dev-tools/index.rst (renamed from Documentation/dev-tools/tools.rst)8
-rw-r--r--Documentation/dev-tools/kcov.rst4
-rw-r--r--Documentation/dev-tools/sparse.rst14
-rw-r--r--Documentation/development-process/index.rst9
-rw-r--r--Documentation/device-mapper/delay.txt4
-rw-r--r--Documentation/device-mapper/dm-crypt.txt27
-rw-r--r--Documentation/device-mapper/dm-raid.txt12
-rw-r--r--Documentation/device-mapper/linear.txt8
-rw-r--r--Documentation/device-mapper/striped.txt4
-rw-r--r--Documentation/device-mapper/switch.txt2
-rw-r--r--Documentation/devicetree/bindings/arm/amlogic,scpi.txt20
-rw-r--r--Documentation/devicetree/bindings/arm/amlogic.txt19
-rw-r--r--Documentation/devicetree/bindings/arm/arch_timer.txt5
-rw-r--r--Documentation/devicetree/bindings/arm/arm,scpi.txt25
-rw-r--r--Documentation/devicetree/bindings/arm/arm-boards3
-rw-r--r--Documentation/devicetree/bindings/arm/atmel-at91.txt16
-rw-r--r--Documentation/devicetree/bindings/arm/bcm/brcm,ns2.txt (renamed from Documentation/devicetree/bindings/arm/bcm/ns2.txt)0
-rw-r--r--Documentation/devicetree/bindings/arm/cpu-capacity.txt236
-rw-r--r--Documentation/devicetree/bindings/arm/cpus.txt11
-rw-r--r--Documentation/devicetree/bindings/arm/fsl.txt34
-rw-r--r--Documentation/devicetree/bindings/arm/hisilicon/hisilicon.txt4
-rw-r--r--Documentation/devicetree/bindings/arm/juno,scpi.txt26
-rw-r--r--Documentation/devicetree/bindings/arm/keystone/ti,sci.txt81
-rw-r--r--Documentation/devicetree/bindings/arm/omap/omap.txt9
-rw-r--r--Documentation/devicetree/bindings/arm/oxnas.txt5
-rw-r--r--Documentation/devicetree/bindings/arm/qcom.txt3
-rw-r--r--Documentation/devicetree/bindings/arm/rockchip.txt16
-rw-r--r--Documentation/devicetree/bindings/arm/samsung/samsung-boards.txt5
-rw-r--r--Documentation/devicetree/bindings/arm/shmobile.txt36
-rw-r--r--Documentation/devicetree/bindings/arm/sunxi.txt1
-rw-r--r--Documentation/devicetree/bindings/arm/swir.txt12
-rw-r--r--Documentation/devicetree/bindings/ata/ahci-fsl-qoriq.txt2
-rw-r--r--Documentation/devicetree/bindings/ata/ahci-st.txt15
-rw-r--r--Documentation/devicetree/bindings/bus/nvidia,tegra20-gmi.txt132
-rw-r--r--Documentation/devicetree/bindings/bus/ti,da850-mstpri.txt20
-rw-r--r--Documentation/devicetree/bindings/clock/exynos5433-clock.txt13
-rw-r--r--Documentation/devicetree/bindings/clock/hisi-crg.txt (renamed from Documentation/devicetree/bindings/clock/hi3519-crg.txt)12
-rw-r--r--Documentation/devicetree/bindings/clock/imx31-clock.txt2
-rw-r--r--Documentation/devicetree/bindings/clock/oxnas,stdclk.txt19
-rw-r--r--Documentation/devicetree/bindings/clock/qcom,gcc.txt1
-rw-r--r--Documentation/devicetree/bindings/clock/qcom,rpmcc.txt37
-rw-r--r--Documentation/devicetree/bindings/clock/qoriq-clock.txt3
-rw-r--r--Documentation/devicetree/bindings/clock/renesas,cpg-mssr.txt5
-rw-r--r--Documentation/devicetree/bindings/clock/rockchip,rk1108-cru.txt59
-rw-r--r--Documentation/devicetree/bindings/clock/st,stm32-rcc.txt4
-rw-r--r--Documentation/devicetree/bindings/clock/sunxi-ccu.txt1
-rw-r--r--Documentation/devicetree/bindings/cpufreq/brcm,stb-avs-cpu-freq.txt78
-rw-r--r--Documentation/devicetree/bindings/crypto/fsl-sec4.txt20
-rw-r--r--Documentation/devicetree/bindings/display/amlogic,meson-vpu.txt112
-rw-r--r--Documentation/devicetree/bindings/display/brcm,bcm-vc4.txt14
-rw-r--r--Documentation/devicetree/bindings/display/bridge/dumb-vga-dac.txt2
-rw-r--r--Documentation/devicetree/bindings/display/bridge/dw_hdmi.txt4
-rw-r--r--Documentation/devicetree/bindings/display/bridge/ti,tfp410.txt (renamed from Documentation/devicetree/bindings/display/ti/ti,tfp410.txt)9
-rw-r--r--Documentation/devicetree/bindings/display/ht16k33.txt42
-rw-r--r--Documentation/devicetree/bindings/display/mxsfb.txt53
-rw-r--r--Documentation/devicetree/bindings/display/panel/auo,g133han01.txt7
-rw-r--r--Documentation/devicetree/bindings/display/panel/auo,g185han01.txt7
-rw-r--r--Documentation/devicetree/bindings/display/panel/auo,t215hvn01.txt7
-rw-r--r--Documentation/devicetree/bindings/display/panel/chunghwa,claa070wp03xg.txt7
-rw-r--r--Documentation/devicetree/bindings/display/panel/display-timing.txt8
-rw-r--r--Documentation/devicetree/bindings/display/panel/nvd,9128.txt7
-rw-r--r--Documentation/devicetree/bindings/display/panel/sharp,lq150x1lg11.txt36
-rw-r--r--Documentation/devicetree/bindings/display/renesas,du.txt12
-rw-r--r--Documentation/devicetree/bindings/display/sunxi/sun4i-drm.txt10
-rw-r--r--Documentation/devicetree/bindings/display/tilcdc/tilcdc.txt6
-rw-r--r--Documentation/devicetree/bindings/display/zte,vou.txt84
-rw-r--r--Documentation/devicetree/bindings/dma/nbpfaxi.txt8
-rw-r--r--Documentation/devicetree/bindings/dma/qcom_hidma_mgmt.txt12
-rw-r--r--Documentation/devicetree/bindings/dma/renesas,rcar-dmac.txt1
-rw-r--r--Documentation/devicetree/bindings/dma/snps-dma.txt2
-rw-r--r--Documentation/devicetree/bindings/dma/st_fdma.txt87
-rw-r--r--Documentation/devicetree/bindings/extcon/extcon-usb-gpio.txt3
-rw-r--r--Documentation/devicetree/bindings/firmware/nvidia,tegra186-bpmp.txt108
-rw-r--r--Documentation/devicetree/bindings/firmware/qcom,scm.txt2
-rw-r--r--Documentation/devicetree/bindings/fpga/altera-fpga2sdram-bridge.txt16
-rw-r--r--Documentation/devicetree/bindings/fpga/altera-freeze-bridge.txt23
-rw-r--r--Documentation/devicetree/bindings/fpga/altera-hps2fpga-bridge.txt39
-rw-r--r--Documentation/devicetree/bindings/fpga/altera-socfpga-a10-fpga-mgr.txt19
-rw-r--r--Documentation/devicetree/bindings/fpga/fpga-region.txt494
-rw-r--r--Documentation/devicetree/bindings/gpio/gpio-sx150x.txt41
-rw-r--r--Documentation/devicetree/bindings/gpio/gpio_oxnas.txt2
-rw-r--r--Documentation/devicetree/bindings/gpio/mrvl-gpio.txt6
-rw-r--r--Documentation/devicetree/bindings/hwmon/mcp3021.txt21
-rw-r--r--Documentation/devicetree/bindings/hwmon/tmp108.txt14
-rw-r--r--Documentation/devicetree/bindings/i2c/i2c-imx-lpi2c.txt20
-rw-r--r--Documentation/devicetree/bindings/i2c/i2c-pxa.txt1
-rw-r--r--Documentation/devicetree/bindings/i2c/i2c-rcar.txt32
-rw-r--r--Documentation/devicetree/bindings/i2c/i2c-sh_mobile.txt17
-rw-r--r--Documentation/devicetree/bindings/i2c/trivial-devices.txt12
-rw-r--r--Documentation/devicetree/bindings/iio/adc/envelope-detector.txt54
-rw-r--r--Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt83
-rw-r--r--Documentation/devicetree/bindings/iio/adc/ti-adc161s626.txt2
-rw-r--r--Documentation/devicetree/bindings/iio/dac/dpot-dac.txt41
-rw-r--r--Documentation/devicetree/bindings/iio/dac/mcp4725.txt35
-rw-r--r--Documentation/devicetree/bindings/iio/gyroscope/invensense,mpu3050.txt46
-rw-r--r--Documentation/devicetree/bindings/iio/humidity/hts221.txt22
-rw-r--r--Documentation/devicetree/bindings/iio/light/isl29018.txt28
-rw-r--r--Documentation/devicetree/bindings/iio/light/tsl2583.txt26
-rw-r--r--Documentation/devicetree/bindings/iio/potentiostat/lmp91000.txt30
-rw-r--r--Documentation/devicetree/bindings/iio/st-sensors.txt1
-rw-r--r--Documentation/devicetree/bindings/leds/pca963x.txt3
-rw-r--r--Documentation/devicetree/bindings/mailbox/brcm,bcm2835-mbox.txt2
-rw-r--r--Documentation/devicetree/bindings/mailbox/nvidia,tegra186-hsp.txt52
-rw-r--r--Documentation/devicetree/bindings/media/exynos5-gsc.txt3
-rw-r--r--Documentation/devicetree/bindings/media/hix5hd2-ir.txt6
-rw-r--r--Documentation/devicetree/bindings/media/i2c/adv7604.txt3
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-rw-r--r--Documentation/devicetree/bindings/media/mediatek-vcodec.txt57
-rw-r--r--Documentation/devicetree/bindings/media/renesas,fcp.txt8
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-rw-r--r--Documentation/devicetree/bindings/media/s5p-mfc.txt1
-rw-r--r--Documentation/devicetree/bindings/memory-controllers/ti-da8xx-ddrctl.txt20
-rw-r--r--Documentation/devicetree/bindings/mfd/lp873x.txt8
-rw-r--r--Documentation/devicetree/bindings/mfd/max77620.txt12
-rw-r--r--Documentation/devicetree/bindings/mfd/tps65086.txt2
-rw-r--r--Documentation/devicetree/bindings/mmc/amlogic,meson-gx.txt32
-rw-r--r--Documentation/devicetree/bindings/mmc/brcm,sdhci-iproc.txt9
-rw-r--r--Documentation/devicetree/bindings/mmc/renesas,mmcif.txt3
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-rw-r--r--Documentation/devicetree/bindings/mmc/sdhci-msm.txt1
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-rw-r--r--Documentation/devicetree/bindings/mmc/synopsys-dw-mshc.txt8
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-rw-r--r--Documentation/devicetree/bindings/net/brcm,amac.txt16
-rw-r--r--Documentation/devicetree/bindings/net/can/rcar_can.txt12
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-rw-r--r--Documentation/devicetree/bindings/net/cpsw.txt8
-rw-r--r--Documentation/devicetree/bindings/net/dsa/marvell.txt24
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-rw-r--r--Documentation/devicetree/bindings/net/hisilicon-hix5hd2-gmac.txt27
-rw-r--r--Documentation/devicetree/bindings/net/hisilicon-hns-dsaf.txt8
-rw-r--r--Documentation/devicetree/bindings/net/marvell-armada-370-neta.txt7
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-rw-r--r--Documentation/devicetree/bindings/net/phy.txt6
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-rw-r--r--Documentation/devicetree/bindings/phy/meson8b-usb2-phy.txt (renamed from Documentation/devicetree/bindings/phy/meson-usb2-phy.txt)6
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-rw-r--r--Documentation/security/tpm/xen-tpmfront.txt (renamed from Documentation/tpm/xen-tpmfront.txt)0
-rw-r--r--Documentation/sound/alsa-configuration.rst2683
-rw-r--r--Documentation/sound/alsa/ALSA-Configuration.txt2330
-rw-r--r--Documentation/sound/alsa/ControlNames.txt107
-rw-r--r--Documentation/sound/alsa/HD-Audio-Models.txt324
-rw-r--r--Documentation/sound/alsa/VIA82xx-mixer.txt8
-rw-r--r--Documentation/sound/alsa/alsa-parameters.txt135
-rw-r--r--Documentation/sound/alsa/seq_oss.html409
-rw-r--r--Documentation/sound/cards/audigy-mixer.rst (renamed from Documentation/sound/alsa/Audigy-mixer.txt)297
-rw-r--r--Documentation/sound/cards/audiophile-usb.rst (renamed from Documentation/sound/alsa/Audiophile-Usb.txt)258
-rw-r--r--Documentation/sound/cards/bt87x.rst (renamed from Documentation/sound/alsa/Bt87x.txt)23
-rw-r--r--Documentation/sound/cards/cmipci.rst (renamed from Documentation/sound/alsa/CMIPCI.txt)62
-rw-r--r--Documentation/sound/cards/emu10k1-jack.rst (renamed from Documentation/sound/alsa/emu10k1-jack.txt)20
-rw-r--r--Documentation/sound/cards/hdspm.rst (renamed from Documentation/sound/alsa/hdspm.txt)253
-rw-r--r--Documentation/sound/cards/img-spdif-in.rst (renamed from Documentation/sound/alsa/img,spdif-in.txt)24
-rw-r--r--Documentation/sound/cards/index.rst19
-rw-r--r--Documentation/sound/cards/joystick.rst (renamed from Documentation/sound/alsa/Joystick.txt)71
-rw-r--r--Documentation/sound/cards/maya44.rst (renamed from Documentation/sound/alsa/README.maya44)137
-rw-r--r--Documentation/sound/cards/mixart.rst (renamed from Documentation/sound/alsa/MIXART.txt)26
-rw-r--r--Documentation/sound/cards/sb-live-mixer.rst (renamed from Documentation/sound/alsa/SB-Live-mixer.txt)337
-rw-r--r--Documentation/sound/cards/serial-u16550.rst (renamed from Documentation/sound/alsa/serial-u16550.txt)21
-rw-r--r--Documentation/sound/cards/via82xx-mixer.rst8
-rw-r--r--Documentation/sound/designs/channel-mapping-api.rst (renamed from Documentation/sound/alsa/Channel-Mapping-API.txt)77
-rw-r--r--Documentation/sound/designs/compress-offload.rst (renamed from Documentation/sound/alsa/compress_offload.txt)127
-rw-r--r--Documentation/sound/designs/control-names.rst142
-rw-r--r--Documentation/sound/designs/index.rst15
-rw-r--r--Documentation/sound/designs/jack-controls.rst (renamed from Documentation/sound/alsa/Jack-Controls.txt)13
-rw-r--r--Documentation/sound/designs/oss-emulation.rst (renamed from Documentation/sound/alsa/OSS-Emulation.txt)169
-rw-r--r--Documentation/sound/designs/powersave.rst (renamed from Documentation/sound/alsa/powersave.txt)16
-rw-r--r--Documentation/sound/designs/procfile.rst (renamed from Documentation/sound/alsa/Procfile.txt)106
-rw-r--r--Documentation/sound/designs/seq-oss.rst371
-rw-r--r--Documentation/sound/designs/timestamping.rst (renamed from Documentation/sound/alsa/timestamping.txt)143
-rw-r--r--Documentation/sound/hd-audio/controls.rst (renamed from Documentation/sound/alsa/HD-Audio-Controls.txt)33
-rw-r--r--Documentation/sound/hd-audio/dp-mst.rst (renamed from Documentation/sound/alsa/HD-Audio-DP-MST-audio.txt)30
-rw-r--r--Documentation/sound/hd-audio/index.rst10
-rw-r--r--Documentation/sound/hd-audio/models.rst518
-rw-r--r--Documentation/sound/hd-audio/notes.rst (renamed from Documentation/sound/alsa/HD-Audio.txt)635
-rw-r--r--Documentation/sound/index.rst20
-rw-r--r--Documentation/sound/kernel-api/alsa-driver-api.rst134
-rw-r--r--Documentation/sound/kernel-api/index.rst8
-rw-r--r--Documentation/sound/kernel-api/writing-an-alsa-driver.rst4219
-rw-r--r--Documentation/sound/oss/oss-parameters.txt2
-rw-r--r--Documentation/sound/soc/clocking.rst (renamed from Documentation/sound/alsa/soc/clocking.txt)13
-rw-r--r--Documentation/sound/soc/codec-to-codec.rst108
-rw-r--r--Documentation/sound/soc/codec.rst (renamed from Documentation/sound/alsa/soc/codec.txt)75
-rw-r--r--Documentation/sound/soc/dai.rst (renamed from Documentation/sound/alsa/soc/DAI.txt)28
-rw-r--r--Documentation/sound/soc/dapm.rst (renamed from Documentation/sound/alsa/soc/dapm.txt)249
-rw-r--r--Documentation/sound/soc/dpcm.rst (renamed from Documentation/sound/alsa/soc/DPCM.txt)280
-rw-r--r--Documentation/sound/soc/index.rst20
-rw-r--r--Documentation/sound/soc/jack.rst (renamed from Documentation/sound/alsa/soc/jack.txt)1
-rw-r--r--Documentation/sound/soc/machine.rst (renamed from Documentation/sound/alsa/soc/machine.txt)22
-rw-r--r--Documentation/sound/soc/overview.rst (renamed from Documentation/sound/alsa/soc/overview.txt)32
-rw-r--r--Documentation/sound/soc/platform.rst (renamed from Documentation/sound/alsa/soc/platform.txt)31
-rw-r--r--Documentation/sound/soc/pops-clicks.rst (renamed from Documentation/sound/alsa/soc/pops_clicks.txt)15
-rw-r--r--Documentation/sphinx/kerneldoc.py (renamed from Documentation/sphinx/kernel-doc.py)0
-rwxr-xr-xDocumentation/sphinx/parse-headers.pl95
-rw-r--r--Documentation/sync_file.txt14
-rw-r--r--Documentation/sysctl/kernel.txt12
-rw-r--r--Documentation/sysfs-rules.txt184
-rw-r--r--Documentation/sysrq.txt257
-rw-r--r--Documentation/trace/events.txt9
-rw-r--r--Documentation/trace/ftrace.txt35
-rw-r--r--Documentation/trace/intel_th.txt22
-rw-r--r--Documentation/trace/stm.txt37
-rw-r--r--Documentation/trace/uprobetracer.txt6
-rw-r--r--Documentation/translations/ja_JP/HOWTO (renamed from Documentation/ja_JP/HOWTO)24
-rw-r--r--Documentation/translations/ja_JP/SubmitChecklist (renamed from Documentation/ja_JP/SubmitChecklist)8
-rw-r--r--Documentation/translations/ja_JP/SubmittingPatches (renamed from Documentation/ja_JP/SubmittingPatches)18
-rw-r--r--Documentation/translations/ja_JP/stable_api_nonsense.txt (renamed from Documentation/ja_JP/stable_api_nonsense.txt)4
-rw-r--r--Documentation/translations/ja_JP/stable_kernel_rules.txt (renamed from Documentation/ja_JP/stable_kernel_rules.txt)6
-rw-r--r--Documentation/translations/ko_KR/howto.rst (renamed from Documentation/ko_KR/HOWTO)172
-rw-r--r--Documentation/translations/ko_KR/index.rst12
-rw-r--r--Documentation/translations/ko_KR/memory-barriers.txt (renamed from Documentation/ko_KR/memory-barriers.txt)36
-rw-r--r--Documentation/translations/ko_KR/stable_api_nonsense.txt (renamed from Documentation/ko_KR/stable_api_nonsense.txt)4
-rw-r--r--Documentation/translations/zh_CN/CodingStyle (renamed from Documentation/zh_CN/CodingStyle)8
-rw-r--r--Documentation/translations/zh_CN/HOWTO (renamed from Documentation/zh_CN/HOWTO)30
-rw-r--r--Documentation/translations/zh_CN/IRQ.txt (renamed from Documentation/zh_CN/IRQ.txt)0
-rw-r--r--Documentation/translations/zh_CN/SecurityBugs (renamed from Documentation/zh_CN/SecurityBugs)6
-rw-r--r--Documentation/translations/zh_CN/SubmittingDrivers (renamed from Documentation/zh_CN/SubmittingDrivers)12
-rw-r--r--Documentation/translations/zh_CN/SubmittingPatches (renamed from Documentation/zh_CN/SubmittingPatches)14
-rw-r--r--Documentation/translations/zh_CN/arm/Booting (renamed from Documentation/zh_CN/arm/Booting)2
-rw-r--r--Documentation/translations/zh_CN/arm/kernel_user_helpers.txt (renamed from Documentation/zh_CN/arm/kernel_user_helpers.txt)0
-rw-r--r--Documentation/translations/zh_CN/arm64/booting.txt (renamed from Documentation/zh_CN/arm64/booting.txt)0
-rw-r--r--Documentation/translations/zh_CN/arm64/legacy_instructions.txt (renamed from Documentation/zh_CN/arm64/legacy_instructions.txt)0
-rw-r--r--Documentation/translations/zh_CN/arm64/memory.txt (renamed from Documentation/zh_CN/arm64/memory.txt)0
-rw-r--r--Documentation/translations/zh_CN/arm64/silicon-errata.txt (renamed from Documentation/zh_CN/arm64/silicon-errata.txt)0
-rw-r--r--Documentation/translations/zh_CN/arm64/tagged-pointers.txt (renamed from Documentation/zh_CN/arm64/tagged-pointers.txt)0
-rw-r--r--Documentation/translations/zh_CN/basic_profiling.txt (renamed from Documentation/zh_CN/basic_profiling.txt)0
-rw-r--r--Documentation/translations/zh_CN/email-clients.txt (renamed from Documentation/zh_CN/email-clients.txt)4
-rw-r--r--Documentation/translations/zh_CN/filesystems/sysfs.txt (renamed from Documentation/zh_CN/filesystems/sysfs.txt)0
-rw-r--r--Documentation/translations/zh_CN/gpio.txt (renamed from Documentation/zh_CN/gpio.txt)0
-rw-r--r--Documentation/translations/zh_CN/io_ordering.txt (renamed from Documentation/zh_CN/io_ordering.txt)0
-rw-r--r--Documentation/translations/zh_CN/magic-number.txt (renamed from Documentation/zh_CN/magic-number.txt)0
-rw-r--r--Documentation/translations/zh_CN/oops-tracing.txt (renamed from Documentation/zh_CN/oops-tracing.txt)6
-rw-r--r--Documentation/translations/zh_CN/sparse.txt (renamed from Documentation/zh_CN/sparse.txt)7
-rw-r--r--Documentation/translations/zh_CN/stable_api_nonsense.txt (renamed from Documentation/zh_CN/stable_api_nonsense.txt)4
-rw-r--r--Documentation/translations/zh_CN/stable_kernel_rules.txt (renamed from Documentation/zh_CN/stable_kernel_rules.txt)6
-rw-r--r--Documentation/translations/zh_CN/video4linux/omap3isp.txt (renamed from Documentation/zh_CN/video4linux/omap3isp.txt)0
-rw-r--r--Documentation/translations/zh_CN/video4linux/v4l2-framework.txt (renamed from Documentation/zh_CN/video4linux/v4l2-framework.txt)0
-rw-r--r--Documentation/translations/zh_CN/volatile-considered-harmful.txt (renamed from Documentation/zh_CN/volatile-considered-harmful.txt)4
-rw-r--r--Documentation/vfio-mediated-device.txt398
-rw-r--r--Documentation/virtual/kvm/00-INDEX2
-rw-r--r--Documentation/virtual/kvm/api.txt5
-rw-r--r--Documentation/virtual/kvm/halt-polling.txt127
-rw-r--r--Documentation/virtual/kvm/msr.txt9
-rw-r--r--Documentation/virtual/kvm/review-checklist.txt4
-rw-r--r--Documentation/vm/numa2
-rw-r--r--Documentation/vm/transhuge.txt5
-rw-r--r--Documentation/watchdog/convert_drivers_to_kernel_api.txt2
-rw-r--r--Documentation/watchdog/watchdog-parameters.txt2
-rw-r--r--Documentation/x86/boot.txt2
-rw-r--r--Documentation/x86/x86_64/boot-options.txt4
677 files changed, 55051 insertions, 25245 deletions
diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX
index 3acc4f1a6f84..c8a8eb1a2b11 100644
--- a/Documentation/00-INDEX
+++ b/Documentation/00-INDEX
@@ -14,13 +14,8 @@ Following translations are available on the WWW:
- this file.
ABI/
- info on kernel <-> userspace ABI and relative interface stability.
-
-BUG-HUNTING
- - brute force method of doing binary search of patches to find bug.
-Changes
- - list of changes that break older software packages.
CodingStyle
- - how the maintainers expect the C code in the kernel to look.
+ - nothing here, just a pointer to process/coding-style.rst.
DMA-API.txt
- DMA API, pci_ API & extensions for non-consistent memory machines.
DMA-API-HOWTO.txt
@@ -33,8 +28,6 @@ DocBook/
- directory with DocBook templates etc. for kernel documentation.
EDID/
- directory with info on customizing EDID for broken gfx/displays.
-HOWTO
- - the process and procedures of how to do Linux kernel development.
IPMI.txt
- info on Linux Intelligent Platform Management Interface (IPMI) Driver.
IRQ-affinity.txt
@@ -46,62 +39,43 @@ IRQ.txt
Intel-IOMMU.txt
- basic info on the Intel IOMMU virtualization support.
Makefile
- - This file does nothing. Removing it breaks make htmldocs and
- make distclean.
-ManagementStyle
- - how to (attempt to) manage kernel hackers.
+ - It's not of interest for those who aren't touching the build system.
+Makefile.sphinx
+ - It's not of interest for those who aren't touching the build system.
+PCI/
+ - info related to PCI drivers.
RCU/
- directory with info on RCU (read-copy update).
SAK.txt
- info on Secure Attention Keys.
SM501.txt
- Silicon Motion SM501 multimedia companion chip
-SecurityBugs
- - procedure for reporting security bugs found in the kernel.
-SubmitChecklist
- - Linux kernel patch submission checklist.
-SubmittingDrivers
- - procedure to get a new driver source included into the kernel tree.
SubmittingPatches
- - procedure to get a source patch included into the kernel tree.
-VGA-softcursor.txt
- - how to change your VGA cursor from a blinking underscore.
+ - nothing here, just a pointer to process/coding-style.rst.
accounting/
- documentation on accounting and taskstats.
acpi/
- info on ACPI-specific hooks in the kernel.
+admin-guide/
+ - info related to Linux users and system admins.
aoe/
- description of AoE (ATA over Ethernet) along with config examples.
-applying-patches.txt
- - description of various trees and how to apply their patches.
arm/
- directory with info about Linux on the ARM architecture.
arm64/
- directory with info about Linux on the 64 bit ARM architecture.
-assoc_array.txt
- - generic associative array intro.
-atomic_ops.txt
- - semantics and behavior of atomic and bitmask operations.
auxdisplay/
- misc. LCD driver documentation (cfag12864b, ks0108).
backlight/
- directory with info on controlling backlights in flat panel displays
-bad_memory.txt
- - how to use kernel parameters to exclude bad RAM regions.
-basic_profiling.txt
- - basic instructions for those who wants to profile Linux kernel.
bcache.txt
- Block-layer cache on fast SSDs to improve slow (raid) I/O performance.
-binfmt_misc.txt
- - info on the kernel support for extra binary formats.
blackfin/
- directory with documentation for the Blackfin arch.
block/
- info on the Block I/O (BIO) layer.
blockdev/
- info on block devices & drivers
-braille-console.txt
- - info on how to use serial devices for Braille support.
bt8xxgpio.txt
- info on how to modify a bt8xx video card for GPIO usage.
btmrvl.txt
@@ -114,18 +88,24 @@ cachetlb.txt
- describes the cache/TLB flushing interfaces Linux uses.
cdrom/
- directory with information on the CD-ROM drivers that Linux has.
-cgroups/
- - cgroups features, including cpusets and memory controller.
+cgroup-v1/
+ - cgroups v1 features, including cpusets and memory controller.
+cgroup-v2.txt
+ - cgroups v2 features, including cpusets and memory controller.
circular-buffers.txt
- how to make use of the existing circular buffer infrastructure
clk.txt
- info on the common clock framework
-coccinelle.txt
- - info on how to get and use the Coccinelle code checking tool.
+cma/
+ - Continuous Memory Area (CMA) debugfs interface.
+conf.py
+ - It's not of interest for those who aren't touching the build system.
connector/
- docs on the netlink based userspace<->kernel space communication mod.
console/
- documentation on Linux console drivers.
+core-api/
+ - documentation on kernel core components.
cpu-freq/
- info on CPU frequency and voltage scaling.
cpu-hotplug.txt
@@ -150,42 +130,42 @@ debugging-via-ohci1394.txt
- how to use firewire like a hardware debugger memory reader.
dell_rbu.txt
- document demonstrating the use of the Dell Remote BIOS Update driver.
-development-process/
- - how to work with the mainline kernel development process.
+dev-tools/
+ - directory with info on development tools for the kernel.
device-mapper/
- directory with info on Device Mapper.
-devices.txt
- - plain ASCII listing of all the nodes in /dev/ with major minor #'s.
+dmaengine/
+ - the DMA engine and controller API guides.
devicetree/
- directory with info on device tree files used by OF/PowerPC/ARM
digsig.txt
-info on the Digital Signature Verification API
dma-buf-sharing.txt
- the DMA Buffer Sharing API Guide
+docutils.conf
+ - nothing here. Just a configuration file for docutils.
dontdiff
- file containing a list of files that should never be diff'ed.
+driver-api/
+ - the Linux driver implementer's API guide.
driver-model/
- directory with info about Linux driver model.
-dvb/
- - info on Linux Digital Video Broadcast (DVB) subsystem.
-dynamic-debug-howto.txt
- - how to use the dynamic debug (dyndbg) feature.
early-userspace/
- info about initramfs, klibc, and userspace early during boot.
-edac.txt
- - information on EDAC - Error Detection And Correction
efi-stub.txt
- How to use the EFI boot stub to bypass GRUB or elilo on EFI systems.
eisa.txt
- info on EISA bus support.
-email-clients.txt
- - info on how to use e-mail to send un-mangled (git) patches.
extcon/
- directory with porting guide for Android kernel switch driver.
+isa.txt
+ - info on EISA bus support.
fault-injection/
- dir with docs about the fault injection capabilities infrastructure.
fb/
- directory with info on the frame buffer graphics abstraction layer.
+features/
+ - status of feature implementation on different architectures.
filesystems/
- info on the vfs and the various filesystems that Linux supports.
firmware_class/
@@ -194,20 +174,22 @@ flexible-arrays.txt
- how to make use of flexible sized arrays in linux
fmc/
- information about the FMC bus abstraction
+fpga/
+ - FPGA Manager Core.
frv/
- Fujitsu FR-V Linux documentation.
futex-requeue-pi.txt
- info on requeueing of tasks from a non-PI futex to a PI futex
-gcov.txt
- - use of GCC's coverage testing tool "gcov" with the Linux kernel
+gcc-plugins.txt
+ - GCC plugin infrastructure.
gpio/
- gpio related documentation
+gpu/
+ - directory with information on GPU driver developer's guide.
hid/
- directory with information on human interface devices
highuid.txt
- notes on the change from 16 bit to 32 bit user/group IDs.
-hsi.txt
- - HSI subsystem overview.
hwspinlock.txt
- hardware spinlock provides hardware assistance for synchronization
timers/
@@ -218,18 +200,18 @@ hwmon/
- directory with docs on various hardware monitoring drivers.
i2c/
- directory with info about the I2C bus/protocol (2 wire, kHz speed).
-i2o/
- - directory with info about the Linux I2O subsystem.
x86/i386/
- directory with info about Linux on Intel 32 bit architecture.
ia64/
- directory with info about Linux on Intel 64 bit architecture.
+ide/
+ - Information regarding the Enhanced IDE drive.
+iio/
+ - info on industrial IIO configfs support.
+index.rst
+ - main index for the documentation at ReST format.
infiniband/
- directory with documents concerning Linux InfiniBand support.
-init.txt
- - what to do when the kernel can't find the 1st process to run.
-initrd.txt
- - how to use the RAM disk as an initial/temporary root filesystem.
input/
- info on Linux input device support.
intel_txt.txt
@@ -248,28 +230,16 @@ isapnp.txt
- info on Linux ISA Plug & Play support.
isdn/
- directory with info on the Linux ISDN support, and supported cards.
-java.txt
- - info on the in-kernel binary support for Java(tm).
-ja_JP/
- - directory with Japanese translations of various documents
kbuild/
- directory with info about the kernel build process.
+kernel-doc-nano-HOWTO.txt
+ - outdated info about kernel-doc documentation.
kdump/
- directory with mini HowTo on getting the crash dump code to work.
-kernel-docs.txt
- - listing of various WWW + books that document kernel internals.
-kernel-documentation.rst
+doc-guide/
- how to write and format reStructuredText kernel documentation
-kernel-parameters.txt
- - summary listing of command line / boot prompt args for the kernel.
kernel-per-CPU-kthreads.txt
- List of all per-CPU kthreads and how they introduce jitter.
-kmemcheck.txt
- - info on dynamic checker that detects uses of uninitialized memory.
-kmemleak.txt
- - info on how to make use of the kernel memory leak detection system
-ko_KR/
- - directory with Korean translations of various documents
kobject.txt
- info of the kobject infrastructure of the Linux kernel.
kprobes.txt
@@ -284,8 +254,8 @@ ldm.txt
- a brief description of LDM (Windows Dynamic Disks).
leds/
- directory with info about LED handling under Linux.
-local_ops.txt
- - semantics and behavior of local atomic operations.
+livepatch/
+ - info on kernel live patching.
locking/
- directory with info about kernel locking primitives
lockup-watchdogs.txt
@@ -298,22 +268,24 @@ lzo.txt
- kernel LZO decompressor input formats
m68k/
- directory with info about Linux on Motorola 68k architecture.
-magic-number.txt
- - list of magic numbers used to mark/protect kernel data structures.
mailbox.txt
- How to write drivers for the common mailbox framework (IPC).
-md.txt
- - info on boot arguments for the multiple devices driver.
-media-framework.txt
- - info on media framework, its data structures, functions and usage.
+md-cluster.txt
+ - info on shared-device RAID MD cluster.
+media/
+ - info on media drivers: uAPI, kAPI and driver documentation.
memory-barriers.txt
- info on Linux kernel memory barriers.
memory-devices/
- directory with info on parts like the Texas Instruments EMIF driver
memory-hotplug.txt
- Hotpluggable memory support, how to use and current status.
+men-chameleon-bus.txt
+ - info on MEN chameleon bus.
metag/
- directory with info about Linux on Meta architecture.
+mic/
+ - Intel Many Integrated Core (MIC) architecture device driver.
mips/
- directory with info about Linux on MIPS architecture.
misc-devices/
@@ -322,12 +294,8 @@ mmc/
- directory with info about the MMC subsystem
mn10300/
- directory with info about the mn10300 architecture port
-module-signing.txt
- - Kernel module signing for increased security when loading modules.
mtd/
- directory with info about memory technology devices (flash)
-mono.txt
- - how to execute Mono-based .NET binaries with the help of BINFMT_MISC.
namespaces/
- directory with various information about namespaces
netlabel/
@@ -336,30 +304,42 @@ networking/
- directory with info on various aspects of networking with Linux.
nfc/
- directory relating info about Near Field Communications support.
+nios2/
+ - Linux on the Nios II architecture.
nommu-mmap.txt
- documentation about no-mmu memory mapping support.
numastat.txt
- info on how to read Numa policy hit/miss statistics in sysfs.
-oops-tracing.txt
- - how to decode those nasty internal kernel error dump messages.
+ntb.txt
+ - info on Non-Transparent Bridge (NTB) drivers.
+nvdimm/
+ - info on non-volatile devices.
+nvmem/
+ - info on non volatile memory framework.
+output/
+ - default directory where html/LaTeX/pdf files will be written.
padata.txt
- An introduction to the "padata" parallel execution API
parisc/
- directory with info on using Linux on PA-RISC architecture.
-parport.txt
- - how to use the parallel-port driver.
parport-lowlevel.txt
- description and usage of the low level parallel port functions.
pcmcia/
- info on the Linux PCMCIA driver.
percpu-rw-semaphore.txt
- RCU based read-write semaphore optimized for locking for reading
+perf/
+ - info about the APM X-Gene SoC Performance Monitoring Unit (PMU).
+phy/
+ - ino on Samsung USB 2.0 PHY adaptation layer.
phy.txt
- Description of the generic PHY framework.
pi-futex.txt
- documentation on lightweight priority inheritance futexes.
pinctrl.txt
- info on pinctrl subsystem and the PINMUX/PINCONF and drivers
+platform/
+ - List of supported hardware by compal and Dell laptop.
pnp.txt
- Linux Plug and Play documentation.
power/
@@ -372,14 +352,16 @@ preempt-locking.txt
- info on locking under a preemptive kernel.
printk-formats.txt
- how to get printk format specifiers right
+process/
+ - how to work with the mainline kernel development process.
pps/
- directory with information on the pulse-per-second support
+pti/
+ - directory with info on Intel MID PTI.
ptp/
- directory with info on support for IEEE 1588 PTP clocks in Linux.
pwm.txt
- info on the pulse width modulation driver subsystem
-ramoops.txt
- - documentation of the ramoops oops/panic logging module.
rapidio/
- directory with info on RapidIO packet-based fabric interconnect
rbtree.txt
@@ -406,8 +388,6 @@ security/
- directory that contains security-related info
serial/
- directory with info on the low level serial API.
-serial-console.txt
- - how to set up Linux with a serial line console as the default.
sgi-ioc4.txt
- description of the SGI IOC4 PCI (multi function) device.
sh/
@@ -416,24 +396,20 @@ smsc_ece1099.txt
-info on the smsc Keyboard Scan Expansion/GPIO Expansion device.
sound/
- directory with info on sound card support.
-sparse.txt
- - info on how to obtain and use the sparse tool for typechecking.
spi/
- overview of Linux kernel Serial Peripheral Interface (SPI) support.
-stable_api_nonsense.txt
- - info on why the kernel does not have a stable in-kernel api or abi.
-stable_kernel_rules.txt
- - rules and procedures for the -stable kernel releases.
+sphinx/
+ - no documentation here, just files required by Sphinx toolchain.
+sphinx-static/
+ - no documentation here, just files required by Sphinx toolchain.
static-keys.txt
- info on how static keys allow debug code in hotpaths via patching
svga.txt
- short guide on selecting video modes at boot via VGA BIOS.
-sysfs-rules.txt
- - How not to use sysfs.
+sync_file.txt
+ - Sync file API guide.
sysctl/
- directory with info on the /proc/sys/* files.
-sysrq.txt
- - info on the magic SysRq key.
target/
- directory with info on generating TCM v4 fabric .ko modules
this_cpu_ops.txt
@@ -442,39 +418,29 @@ thermal/
- directory with information on managing thermal issues (CPU/temp)
trace/
- directory with info on tracing technologies within linux
+translations/
+ - translations of this document from English to another language
unaligned-memory-access.txt
- info on how to avoid arch breaking unaligned memory access in code.
-unicode.txt
- - info on the Unicode character/font mapping used in Linux.
unshare.txt
- description of the Linux unshare system call.
usb/
- directory with info regarding the Universal Serial Bus.
-vDSO/
- - directory with info regarding virtual dynamic shared objects
vfio.txt
- info on Virtual Function I/O used in guest/hypervisor instances.
-vgaarbiter.txt
- - info on enable/disable the legacy decoding on different VGA devices
video-output.txt
- sysfs class driver interface to enable/disable a video output device.
-video4linux/
- - directory with info regarding video/TV/radio cards and linux.
virtual/
- directory with information on the various linux virtualizations.
vm/
- directory with info on the Linux vm code.
-vme_api.txt
- - file relating info on the VME bus API in linux
-volatile-considered-harmful.txt
- - Why the "volatile" type class should not be used
w1/
- directory with documents regarding the 1-wire (w1) subsystem.
watchdog/
- how to auto-reboot Linux if it has "fallen and can't get up". ;-)
wimax/
- directory with info about Intel Wireless Wimax Connections
-workqueue.txt
+core-api/workqueue.rst
- information on the Concurrency Managed Workqueue implementation
x86/x86_64/
- directory with info on Linux support for AMD x86-64 (Hammer) machines.
@@ -484,7 +450,5 @@ xtensa/
- directory with documents relating to arch/xtensa port/implementation
xz.txt
- how to make use of the XZ data compression within linux kernel
-zh_CN/
- - directory with Chinese translations of various documents
zorro.txt
- info on writing drivers for Zorro bus devices found on Amigas.
diff --git a/Documentation/ABI/README b/Documentation/ABI/README
index 1fafc4b0753b..3121029dce21 100644
--- a/Documentation/ABI/README
+++ b/Documentation/ABI/README
@@ -84,4 +84,4 @@ stable:
- Kernel-internal symbols. Do not rely on the presence, absence, location, or
type of any kernel symbol, either in System.map files or the kernel binary
- itself. See Documentation/stable_api_nonsense.txt.
+ itself. See Documentation/process/stable-api-nonsense.rst.
diff --git a/Documentation/ABI/stable/sysfs-devices b/Documentation/ABI/stable/sysfs-devices
index df449d79b563..35c457f8ce73 100644
--- a/Documentation/ABI/stable/sysfs-devices
+++ b/Documentation/ABI/stable/sysfs-devices
@@ -8,3 +8,17 @@ Description:
Any device associated with a device-tree node will have
an of_path symlink pointing to the corresponding device
node in /sys/firmware/devicetree/
+
+What: /sys/devices/*/devspec
+Date: October 2016
+Contact: Device Tree mailing list <devicetree@vger.kernel.org>
+Description:
+ If CONFIG_OF is enabled, then this file is present. When
+ read, it returns full name of the device node.
+
+What: /sys/devices/*/obppath
+Date: October 2016
+Contact: Device Tree mailing list <devicetree@vger.kernel.org>
+Description:
+ If CONFIG_OF is enabled, then this file is present. When
+ read, it returns full name of the device node.
diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block
index 71d184dbb70d..2da04ce6aeef 100644
--- a/Documentation/ABI/testing/sysfs-block
+++ b/Documentation/ABI/testing/sysfs-block
@@ -235,3 +235,45 @@ Description:
write_same_max_bytes is 0, write same is not supported
by the device.
+What: /sys/block/<disk>/queue/write_zeroes_max_bytes
+Date: November 2016
+Contact: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
+Description:
+ Devices that support write zeroes operation in which a
+ single request can be issued to zero out the range of
+ contiguous blocks on storage without having any payload
+ in the request. This can be used to optimize writing zeroes
+ to the devices. write_zeroes_max_bytes indicates how many
+ bytes can be written in a single write zeroes command. If
+ write_zeroes_max_bytes is 0, write zeroes is not supported
+ by the device.
+
+What: /sys/block/<disk>/queue/zoned
+Date: September 2016
+Contact: Damien Le Moal <damien.lemoal@hgst.com>
+Description:
+ zoned indicates if the device is a zoned block device
+ and the zone model of the device if it is indeed zoned.
+ The possible values indicated by zoned are "none" for
+ regular block devices and "host-aware" or "host-managed"
+ for zoned block devices. The characteristics of
+ host-aware and host-managed zoned block devices are
+ described in the ZBC (Zoned Block Commands) and ZAC
+ (Zoned Device ATA Command Set) standards. These standards
+ also define the "drive-managed" zone model. However,
+ since drive-managed zoned block devices do not support
+ zone commands, they will be treated as regular block
+ devices and zoned will report "none".
+
+What: /sys/block/<disk>/queue/chunk_sectors
+Date: September 2016
+Contact: Hannes Reinecke <hare@suse.com>
+Description:
+ chunk_sectors has different meaning depending on the type
+ of the disk. For a RAID device (dm-raid), chunk_sectors
+ indicates the size in 512B sectors of the RAID volume
+ stripe segment. For a zoned block device, either
+ host-aware or host-managed, chunk_sectors indicates the
+ size of 512B sectors of the zones of the device, with
+ the eventual exception of the last zone of the device
+ which may be smaller.
diff --git a/Documentation/ABI/testing/sysfs-bus-fsl-mc b/Documentation/ABI/testing/sysfs-bus-fsl-mc
new file mode 100644
index 000000000000..80256b8b4f26
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-fsl-mc
@@ -0,0 +1,21 @@
+What: /sys/bus/fsl-mc/drivers/.../bind
+Date: December 2016
+Contact: stuart.yoder@nxp.com
+Description:
+ Writing a device location to this file will cause
+ the driver to attempt to bind to the device found at
+ this location. The format for the location is Object.Id
+ and is the same as found in /sys/bus/fsl-mc/devices/.
+ For example:
+ # echo dpni.2 > /sys/bus/fsl-mc/drivers/fsl_dpaa2_eth/bind
+
+What: /sys/bus/fsl-mc/drivers/.../unbind
+Date: December 2016
+Contact: stuart.yoder@nxp.com
+Description:
+ Writing a device location to this file will cause the
+ driver to attempt to unbind from the device found at
+ this location. The format for the location is Object.Id
+ and is the same as found in /sys/bus/fsl-mc/devices/.
+ For example:
+ # echo dpni.2 > /sys/bus/fsl-mc/drivers/fsl_dpaa2_eth/unbind
diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index fee35c00cc4e..b8f220f978dd 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -329,6 +329,7 @@ What: /sys/bus/iio/devices/iio:deviceX/in_pressure_scale
What: /sys/bus/iio/devices/iio:deviceX/in_humidityrelative_scale
What: /sys/bus/iio/devices/iio:deviceX/in_velocity_sqrt(x^2+y^2+z^2)_scale
What: /sys/bus/iio/devices/iio:deviceX/in_illuminance_scale
+What: /sys/bus/iio/devices/iio:deviceX/in_countY_scale
KernelVersion: 2.6.35
Contact: linux-iio@vger.kernel.org
Description:
@@ -1579,3 +1580,20 @@ Contact: linux-iio@vger.kernel.org
Description:
Raw (unscaled no offset etc.) electric conductivity reading that
can be processed to siemens per meter.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_countY_raw
+KernelVersion: 4.9
+Contact: linux-iio@vger.kernel.org
+Description:
+ Raw counter device counts from channel Y. For quadrature
+ counters, multiplication by an available [Y]_scale results in
+ the counts of a single quadrature signal phase from channel Y.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_indexY_raw
+KernelVersion: 4.9
+Contact: linux-iio@vger.kernel.org
+Description:
+ Raw counter device index value from channel Y. This attribute
+ provides an absolute positional reference (e.g. a pulse once per
+ revolution) which may be used to home positional systems as
+ required.
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-envelope-detector b/Documentation/ABI/testing/sysfs-bus-iio-adc-envelope-detector
new file mode 100644
index 000000000000..2071f9bcfaa5
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-envelope-detector
@@ -0,0 +1,36 @@
+What: /sys/bus/iio/devices/iio:deviceX/in_altvoltageY_invert
+Date: October 2016
+KernelVersion: 4.9
+Contact: Peter Rosin <peda@axentia.se>
+Description:
+ The DAC is used to find the peak level of an alternating
+ voltage input signal by a binary search using the output
+ of a comparator wired to an interrupt pin. Like so:
+ _
+ | \
+ input +------>-------|+ \
+ | \
+ .-------. | }---.
+ | | | / |
+ | dac|-->--|- / |
+ | | |_/ |
+ | | |
+ | | |
+ | irq|------<-------'
+ | |
+ '-------'
+ The boolean invert attribute (0/1) should be set when the
+ input signal is centered around the maximum value of the
+ dac instead of zero. The envelope detector will search
+ from below in this case and will also invert the result.
+ The edge/level of the interrupt is also switched to its
+ opposite value.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_altvoltageY_compare_interval
+Date: October 2016
+KernelVersion: 4.9
+Contact: Peter Rosin <peda@axentia.se>
+Description:
+ Number of milliseconds to wait for the comparator in each
+ step of the binary search for the input peak level. Needs
+ to relate to the frequency of the input signal.
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8 b/Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8
new file mode 100644
index 000000000000..ba676520b953
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-counter-104-quad-8
@@ -0,0 +1,125 @@
+What: /sys/bus/iio/devices/iio:deviceX/in_count_count_direction_available
+What: /sys/bus/iio/devices/iio:deviceX/in_count_count_mode_available
+What: /sys/bus/iio/devices/iio:deviceX/in_count_noise_error_available
+What: /sys/bus/iio/devices/iio:deviceX/in_count_quadrature_mode_available
+What: /sys/bus/iio/devices/iio:deviceX/in_index_index_polarity_available
+What: /sys/bus/iio/devices/iio:deviceX/in_index_synchronous_mode_available
+KernelVersion: 4.9
+Contact: linux-iio@vger.kernel.org
+Description:
+ Discrete set of available values for the respective counter
+ configuration are listed in this file.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_countY_count_direction
+KernelVersion: 4.9
+Contact: linux-iio@vger.kernel.org
+Description:
+ Read-only attribute that indicates whether the counter for
+ channel Y is counting up or down.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_countY_count_mode
+KernelVersion: 4.9
+Contact: linux-iio@vger.kernel.org
+Description:
+ Count mode for channel Y. Four count modes are available:
+ normal, range limit, non-recycle, and modulo-n. The preset value
+ for channel Y is used by the count mode where required.
+
+ Normal:
+ Counting is continuous in either direction.
+
+ Range Limit:
+ An upper or lower limit is set, mimicking limit switches
+ in the mechanical counterpart. The upper limit is set to
+ the preset value, while the lower limit is set to 0. The
+ counter freezes at count = preset when counting up, and
+ at count = 0 when counting down. At either of these
+ limits, the counting is resumed only when the count
+ direction is reversed.
+
+ Non-recycle:
+ Counter is disabled whenever a 24-bit count overflow or
+ underflow takes place. The counter is re-enabled when a
+ new count value is loaded to the counter via a preset
+ operation or write to raw.
+
+ Modulo-N:
+ A count boundary is set between 0 and the preset value.
+ The counter is reset to 0 at count = preset when
+ counting up, while the counter is set to the preset
+ value at count = 0 when counting down; the counter does
+ not freeze at the bundary points, but counts
+ continuously throughout.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_countY_noise_error
+KernelVersion: 4.9
+Contact: linux-iio@vger.kernel.org
+Description:
+ Read-only attribute that indicates whether excessive noise is
+ present at the channel Y count inputs in quadrature clock mode;
+ irrelevant in non-quadrature clock mode.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_countY_preset
+KernelVersion: 4.9
+Contact: linux-iio@vger.kernel.org
+Description:
+ If the counter device supports preset registers, the preset
+ count for channel Y is provided by this attribute.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_countY_quadrature_mode
+KernelVersion: 4.9
+Contact: linux-iio@vger.kernel.org
+Description:
+ Configure channel Y counter for non-quadrature or quadrature
+ clock mode. Selecting non-quadrature clock mode will disable
+ synchronous load mode. In quadrature clock mode, the channel Y
+ scale attribute selects the encoder phase division (scale of 1
+ selects full-cycle, scale of 0.5 selects half-cycle, scale of
+ 0.25 selects quarter-cycle) processed by the channel Y counter.
+
+ Non-quadrature:
+ The filter and decoder circuit are bypassed. Encoder A
+ input serves as the count input and B as the UP/DOWN
+ direction control input, with B = 1 selecting UP Count
+ mode and B = 0 selecting Down Count mode.
+
+ Quadrature:
+ Encoder A and B inputs are digitally filtered and
+ decoded for UP/DN clock.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_countY_set_to_preset_on_index
+KernelVersion: 4.9
+Contact: linux-iio@vger.kernel.org
+Description:
+ Whether to set channel Y counter with channel Y preset value
+ when channel Y index input is active, or continuously count.
+ Valid attribute values are boolean.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_indexY_index_polarity
+KernelVersion: 4.9
+Contact: linux-iio@vger.kernel.org
+Description:
+ Active level of channel Y index input; irrelevant in
+ non-synchronous load mode.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_indexY_synchronous_mode
+KernelVersion: 4.9
+Contact: linux-iio@vger.kernel.org
+Description:
+ Configure channel Y counter for non-synchronous or synchronous
+ load mode. Synchronous load mode cannot be selected in
+ non-quadrature clock mode.
+
+ Non-synchronous:
+ A logic low level is the active level at this index
+ input. The index function (as enabled via
+ set_to_preset_on_index) is performed directly on the
+ active level of the index input.
+
+ Synchronous:
+ Intended for interfacing with encoder Index output in
+ quadrature clock mode. The active level is configured
+ via index_polarity. The index function (as enabled via
+ set_to_preset_on_index) is performed synchronously with
+ the quadrature clock on the active level of the index
+ input.
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-cros-ec b/Documentation/ABI/testing/sysfs-bus-iio-cros-ec
new file mode 100644
index 000000000000..297b9720f024
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-cros-ec
@@ -0,0 +1,18 @@
+What: /sys/bus/iio/devices/iio:deviceX/calibrate
+Date: July 2015
+KernelVersion: 4.7
+Contact: linux-iio@vger.kernel.org
+Description:
+ Writing '1' will perform a FOC (Fast Online Calibration). The
+ corresponding calibration offsets can be read from *_calibbias
+ entries.
+
+What: /sys/bus/iio/devices/iio:deviceX/location
+Date: July 2015
+KernelVersion: 4.7
+Contact: linux-iio@vger.kernel.org
+Description:
+ This attribute returns a string with the physical location where
+ the motion sensor is placed. For example, in a laptop a motion
+ sensor can be located on the base or on the lid. Current valid
+ values are 'base' and 'lid'.
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-dac-dpot-dac b/Documentation/ABI/testing/sysfs-bus-iio-dac-dpot-dac
new file mode 100644
index 000000000000..580e93f373f6
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-dac-dpot-dac
@@ -0,0 +1,8 @@
+What: /sys/bus/iio/devices/iio:deviceX/out_voltageY_raw_available
+Date: October 2016
+KernelVersion: 4.9
+Contact: Peter Rosin <peda@axentia.se>
+Description:
+ The range of available values represented as the minimum value,
+ the step and the maximum value, all enclosed in square brackets.
+ Example: [0 1 256]
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-light-isl29018 b/Documentation/ABI/testing/sysfs-bus-iio-light-isl29018
new file mode 100644
index 000000000000..f0ce0a0476ea
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-light-isl29018
@@ -0,0 +1,19 @@
+What: /sys/bus/iio/devices/iio:deviceX/proximity_on_chip_ambient_infrared_suppression
+Date: January 2011
+KernelVersion: 2.6.37
+Contact: linux-iio@vger.kernel.org
+Description:
+ From ISL29018 Data Sheet (FN6619.4, Oct 8, 2012) regarding the
+ infrared suppression:
+
+ Scheme 0, makes full n (4, 8, 12, 16) bits (unsigned) proximity
+ detection. The range of Scheme 0 proximity count is from 0 to
+ 2^n. Logic 1 of this bit, Scheme 1, makes n-1 (3, 7, 11, 15)
+ bits (2's complementary) proximity_less_ambient detection. The
+ range of Scheme 1 proximity count is from -2^(n-1) to 2^(n-1).
+ The sign bit is extended for resolutions less than 16. While
+ Scheme 0 has wider dynamic range, Scheme 1 proximity detection
+ is less affected by the ambient IR noise variation.
+
+ 0 Sensing IR from LED and ambient
+ 1 Sensing IR from LED with ambient IR rejection
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-light-tsl2583 b/Documentation/ABI/testing/sysfs-bus-iio-light-tsl2583
new file mode 100644
index 000000000000..a2e19964e87e
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-light-tsl2583
@@ -0,0 +1,20 @@
+What: /sys/bus/iio/devices/device[n]/in_illuminance_calibrate
+KernelVersion: 2.6.37
+Contact: linux-iio@vger.kernel.org
+Description:
+ This property causes an internal calibration of the als gain trim
+ value which is later used in calculating illuminance in lux.
+
+What: /sys/bus/iio/devices/device[n]/in_illuminance_lux_table
+KernelVersion: 2.6.37
+Contact: linux-iio@vger.kernel.org
+Description:
+ This property gets/sets the table of coefficients
+ used in calculating illuminance in lux.
+
+What: /sys/bus/iio/devices/device[n]/in_illuminance_input_target
+KernelVersion: 2.6.37
+Contact: linux-iio@vger.kernel.org
+Description:
+ This property is the known externally illuminance (in lux).
+ It is used in the process of calibrating the device accuracy.
diff --git a/Documentation/ABI/testing/sysfs-bus-iio-potentiometer-mcp4531 b/Documentation/ABI/testing/sysfs-bus-iio-potentiometer-mcp4531
new file mode 100644
index 000000000000..2a91fbe394fc
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-potentiometer-mcp4531
@@ -0,0 +1,8 @@
+What: /sys/bus/iio/devices/iio:deviceX/out_resistance_raw_available
+Date: October 2016
+KernelVersion: 4.9
+Contact: Peter Rosin <peda@axentia.se>
+Description:
+ The range of available values represented as the minimum value,
+ the step and the maximum value, all enclosed in square brackets.
+ Example: [0 1 256]
diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci
index b3bc50f650ee..5a1732b78707 100644
--- a/Documentation/ABI/testing/sysfs-bus-pci
+++ b/Documentation/ABI/testing/sysfs-bus-pci
@@ -294,3 +294,10 @@ Description:
a firmware bug to the system vendor. Writing to this file
taints the kernel with TAINT_FIRMWARE_WORKAROUND, which
reduces the supportability of your system.
+
+What: /sys/bus/pci/devices/.../revision
+Date: November 2016
+Contact: Emil Velikov <emil.l.velikov@gmail.com>
+Description:
+ This file contains the revision field of the the PCI device.
+ The value comes from device config space. The file is read only.
diff --git a/Documentation/ABI/testing/sysfs-bus-vfio-mdev b/Documentation/ABI/testing/sysfs-bus-vfio-mdev
new file mode 100644
index 000000000000..452dbe39270e
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-vfio-mdev
@@ -0,0 +1,111 @@
+What: /sys/.../<device>/mdev_supported_types/
+Date: October 2016
+Contact: Kirti Wankhede <kwankhede@nvidia.com>
+Description:
+ This directory contains list of directories of currently
+ supported mediated device types and their details for
+ <device>. Supported type attributes are defined by the
+ vendor driver who registers with Mediated device framework.
+ Each supported type is a directory whose name is created
+ by adding the device driver string as a prefix to the
+ string provided by the vendor driver.
+
+What: /sys/.../<device>/mdev_supported_types/<type-id>/
+Date: October 2016
+Contact: Kirti Wankhede <kwankhede@nvidia.com>
+Description:
+ This directory gives details of supported type, like name,
+ description, available_instances, device_api etc.
+ 'device_api' and 'available_instances' are mandatory
+ attributes to be provided by vendor driver. 'name',
+ 'description' and other vendor driver specific attributes
+ are optional.
+
+What: /sys/.../mdev_supported_types/<type-id>/create
+Date: October 2016
+Contact: Kirti Wankhede <kwankhede@nvidia.com>
+Description:
+ Writing UUID to this file will create mediated device of
+ type <type-id> for parent device <device>. This is a
+ write-only file.
+ For example:
+ # echo "83b8f4f2-509f-382f-3c1e-e6bfe0fa1001" > \
+ /sys/devices/foo/mdev_supported_types/foo-1/create
+
+What: /sys/.../mdev_supported_types/<type-id>/devices/
+Date: October 2016
+Contact: Kirti Wankhede <kwankhede@nvidia.com>
+Description:
+ This directory contains symbolic links pointing to mdev
+ devices sysfs entries which are created of this <type-id>.
+
+What: /sys/.../mdev_supported_types/<type-id>/available_instances
+Date: October 2016
+Contact: Kirti Wankhede <kwankhede@nvidia.com>
+Description:
+ Reading this attribute will show the number of mediated
+ devices of type <type-id> that can be created. This is a
+ readonly file.
+Users:
+ Userspace applications interested in creating mediated
+ device of that type. Userspace application should check
+ the number of available instances could be created before
+ creating mediated device of this type.
+
+What: /sys/.../mdev_supported_types/<type-id>/device_api
+Date: October 2016
+Contact: Kirti Wankhede <kwankhede@nvidia.com>
+Description:
+ Reading this attribute will show VFIO device API supported
+ by this type. For example, "vfio-pci" for a PCI device,
+ "vfio-platform" for platform device.
+
+What: /sys/.../mdev_supported_types/<type-id>/name
+Date: October 2016
+Contact: Kirti Wankhede <kwankhede@nvidia.com>
+Description:
+ Reading this attribute will show human readable name of the
+ mediated device that will get created of type <type-id>.
+ This is optional attribute. For example: "Grid M60-0Q"
+Users:
+ Userspace applications interested in knowing the name of
+ a particular <type-id> that can help in understanding the
+ type of mediated device.
+
+What: /sys/.../mdev_supported_types/<type-id>/description
+Date: October 2016
+Contact: Kirti Wankhede <kwankhede@nvidia.com>
+Description:
+ Reading this attribute will show description of the type of
+ mediated device that will get created of type <type-id>.
+ This is optional attribute. For example:
+ "2 heads, 512M FB, 2560x1600 maximum resolution"
+Users:
+ Userspace applications interested in knowing the details of
+ a particular <type-id> that can help in understanding the
+ features provided by that type of mediated device.
+
+What: /sys/.../<device>/<UUID>/
+Date: October 2016
+Contact: Kirti Wankhede <kwankhede@nvidia.com>
+Description:
+ This directory represents device directory of mediated
+ device. It contains all the attributes related to mediated
+ device.
+
+What: /sys/.../<device>/<UUID>/mdev_type
+Date: October 2016
+Contact: Kirti Wankhede <kwankhede@nvidia.com>
+Description:
+ This is symbolic link pointing to supported type, <type-id>
+ directory of which this mediated device is created.
+
+What: /sys/.../<device>/<UUID>/remove
+Date: October 2016
+Contact: Kirti Wankhede <kwankhede@nvidia.com>
+Description:
+ Writing '1' to this file destroys the mediated device. The
+ vendor driver can fail the remove() callback if that device
+ is active and the vendor driver doesn't support hot unplug.
+ Example:
+ # echo 1 > /sys/bus/mdev/devices/<UUID>/remove
diff --git a/Documentation/ABI/testing/sysfs-class-fpga-bridge b/Documentation/ABI/testing/sysfs-class-fpga-bridge
new file mode 100644
index 000000000000..312ae2c579d8
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-fpga-bridge
@@ -0,0 +1,11 @@
+What: /sys/class/fpga_bridge/<bridge>/name
+Date: January 2016
+KernelVersion: 4.5
+Contact: Alan Tull <atull@opensource.altera.com>
+Description: Name of low level FPGA bridge driver.
+
+What: /sys/class/fpga_bridge/<bridge>/state
+Date: January 2016
+KernelVersion: 4.5
+Contact: Alan Tull <atull@opensource.altera.com>
+Description: Show bridge state as "enabled" or "disabled"
diff --git a/Documentation/ABI/testing/sysfs-class-led b/Documentation/ABI/testing/sysfs-class-led
index 86ace287d48b..491cdeedc195 100644
--- a/Documentation/ABI/testing/sysfs-class-led
+++ b/Documentation/ABI/testing/sysfs-class-led
@@ -4,16 +4,24 @@ KernelVersion: 2.6.17
Contact: Richard Purdie <rpurdie@rpsys.net>
Description:
Set the brightness of the LED. Most LEDs don't
- have hardware brightness support so will just be turned on for
+ have hardware brightness support, so will just be turned on for
non-zero brightness settings. The value is between 0 and
/sys/class/leds/<led>/max_brightness.
+ Writing 0 to this file clears active trigger.
+
+ Writing non-zero to this file while trigger is active changes the
+ top brightness trigger is going to use.
+
What: /sys/class/leds/<led>/max_brightness
Date: March 2006
KernelVersion: 2.6.17
Contact: Richard Purdie <rpurdie@rpsys.net>
Description:
- Maximum brightness level for this led, default is 255 (LED_FULL).
+ Maximum brightness level for this LED, default is 255 (LED_FULL).
+
+ If the LED does not support different brightness levels, this
+ should be 1.
What: /sys/class/leds/<led>/trigger
Date: March 2006
@@ -21,7 +29,7 @@ KernelVersion: 2.6.17
Contact: Richard Purdie <rpurdie@rpsys.net>
Description:
Set the trigger for this LED. A trigger is a kernel based source
- of led events.
+ of LED events.
You can change triggers in a similar manner to the way an IO
scheduler is chosen. Trigger specific parameters can appear in
/sys/class/leds/<led> once a given trigger is selected. For
diff --git a/Documentation/ABI/testing/sysfs-class-mei b/Documentation/ABI/testing/sysfs-class-mei
index 80d9888a8ece..5096a82f4cde 100644
--- a/Documentation/ABI/testing/sysfs-class-mei
+++ b/Documentation/ABI/testing/sysfs-class-mei
@@ -29,3 +29,19 @@ Description: Display fw status registers content
Also number of registers varies between 1 and 6
depending on generation.
+What: /sys/class/mei/meiN/hbm_ver
+Date: Aug 2016
+KernelVersion: 4.9
+Contact: Tomas Winkler <tomas.winkler@intel.com>
+Description: Display the negotiated HBM protocol version.
+
+ The HBM protocol version negotiated
+ between the driver and the device.
+
+What: /sys/class/mei/meiN/hbm_ver_drv
+Date: Aug 2016
+KernelVersion: 4.9
+Contact: Tomas Winkler <tomas.winkler@intel.com>
+Description: Display the driver HBM protocol version.
+
+ The HBM protocol version supported by the driver.
diff --git a/Documentation/ABI/testing/sysfs-class-remoteproc b/Documentation/ABI/testing/sysfs-class-remoteproc
new file mode 100644
index 000000000000..d188afebc8ba
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-remoteproc
@@ -0,0 +1,50 @@
+What: /sys/class/remoteproc/.../firmware
+Date: October 2016
+Contact: Matt Redfearn <matt.redfearn@imgtec.com>
+Description: Remote processor firmware
+
+ Reports the name of the firmware currently loaded to the
+ remote processor.
+
+ To change the running firmware, ensure the remote processor is
+ stopped (using /sys/class/remoteproc/.../state) and write a new filename.
+
+What: /sys/class/remoteproc/.../state
+Date: October 2016
+Contact: Matt Redfearn <matt.redfearn@imgtec.com>
+Description: Remote processor state
+
+ Reports the state of the remote processor, which will be one of:
+
+ "offline"
+ "suspended"
+ "running"
+ "crashed"
+ "invalid"
+
+ "offline" means the remote processor is powered off.
+
+ "suspended" means that the remote processor is suspended and
+ must be woken to receive messages.
+
+ "running" is the normal state of an available remote processor
+
+ "crashed" indicates that a problem/crash has been detected on
+ the remote processor.
+
+ "invalid" is returned if the remote processor is in an
+ unknown state.
+
+ Writing this file controls the state of the remote processor.
+ The following states can be written:
+
+ "start"
+ "stop"
+
+ Writing "start" will attempt to start the processor running the
+ firmware indicated by, or written to,
+ /sys/class/remoteproc/.../firmware. The remote processor should
+ transition to "running" state.
+
+ Writing "stop" will attempt to halt the remote processor and
+ return it to the "offline" state.
diff --git a/Documentation/ABI/testing/sysfs-devices-deferred_probe b/Documentation/ABI/testing/sysfs-devices-deferred_probe
new file mode 100644
index 000000000000..58553d7a321f
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-deferred_probe
@@ -0,0 +1,12 @@
+What: /sys/devices/.../deferred_probe
+Date: August 2016
+Contact: Ben Hutchings <ben.hutchings@codethink.co.uk>
+Description:
+ The /sys/devices/.../deferred_probe attribute is
+ present for all devices. If a driver detects during
+ probing a device that a related device is not yet
+ ready, it may defer probing of the first device. The
+ kernel will retry probing the first device after any
+ other device is successfully probed. This attribute
+ reads as 1 if probing of this device is currently
+ deferred, or 0 otherwise.
diff --git a/Documentation/ABI/testing/sysfs-kernel-slab b/Documentation/ABI/testing/sysfs-kernel-slab
index 91bd6ca5440f..2cc0a72b64be 100644
--- a/Documentation/ABI/testing/sysfs-kernel-slab
+++ b/Documentation/ABI/testing/sysfs-kernel-slab
@@ -347,7 +347,7 @@ Description:
because of fragmentation, SLUB will retry with the minimum order
possible depending on its characteristics.
When debug_guardpage_minorder=N (N > 0) parameter is specified
- (see Documentation/kernel-parameters.txt), the minimum possible
+ (see Documentation/admin-guide/kernel-parameters.rst), the minimum possible
order is used and this sysfs entry can not be used to change
the order at run time.
diff --git a/Documentation/ABI/testing/sysfs-platform-phy-rcar-gen3-usb2 b/Documentation/ABI/testing/sysfs-platform-phy-rcar-gen3-usb2
new file mode 100644
index 000000000000..6212697bbf6f
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-platform-phy-rcar-gen3-usb2
@@ -0,0 +1,15 @@
+What: /sys/devices/platform/<phy-name>/role
+Date: October 2016
+KernelVersion: 4.10
+Contact: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
+Description:
+ This file can be read and write.
+ The file can show/change the phy mode for role swap of usb.
+
+ Write the following strings to change the mode:
+ "host" - switching mode from peripheral to host.
+ "peripheral" - switching mode from host to peripheral.
+
+ Read the file, then it shows the following strings:
+ "host" - The mode is host now.
+ "peripheral" - The mode is peripheral now.
diff --git a/Documentation/ABI/testing/sysfs-platform-sst-atom b/Documentation/ABI/testing/sysfs-platform-sst-atom
new file mode 100644
index 000000000000..0d07c0395660
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-platform-sst-atom
@@ -0,0 +1,17 @@
+What: /sys/devices/platform/8086%x:00/firmware_version
+Date: November 2016
+KernelVersion: 4.10
+Contact: "Sebastien Guiriec" <sebastien.guiriec@intel.com>
+Description:
+ LPE Firmware version for SST driver on all atom
+ plaforms (BYT/CHT/Merrifield/BSW).
+ If the FW has never been loaded it will display:
+ "FW not yet loaded"
+ If FW has been loaded it will display:
+ "v01.aa.bb.cc"
+ aa: Major version is reflecting SoC version:
+ 0d: BYT FW
+ 0b: BSW FW
+ 07: Merrifield FW
+ bb: Minor version
+ cc: Build version
diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power
index 50b368d490b5..f523e5a3ac33 100644
--- a/Documentation/ABI/testing/sysfs-power
+++ b/Documentation/ABI/testing/sysfs-power
@@ -7,30 +7,35 @@ Description:
subsystem.
What: /sys/power/state
-Date: May 2014
+Date: November 2016
Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
Description:
The /sys/power/state file controls system sleep states.
Reading from this file returns the available sleep state
- labels, which may be "mem", "standby", "freeze" and "disk"
- (hibernation). The meanings of the first three labels depend on
- the relative_sleep_states command line argument as follows:
- 1) relative_sleep_states = 1
- "mem", "standby", "freeze" represent non-hibernation sleep
- states from the deepest ("mem", always present) to the
- shallowest ("freeze"). "standby" and "freeze" may or may
- not be present depending on the capabilities of the
- platform. "freeze" can only be present if "standby" is
- present.
- 2) relative_sleep_states = 0 (default)
- "mem" - "suspend-to-RAM", present if supported.
- "standby" - "power-on suspend", present if supported.
- "freeze" - "suspend-to-idle", always present.
-
- Writing to this file one of these strings causes the system to
- transition into the corresponding state, if available. See
- Documentation/power/states.txt for a description of what
- "suspend-to-RAM", "power-on suspend" and "suspend-to-idle" mean.
+ labels, which may be "mem" (suspend), "standby" (power-on
+ suspend), "freeze" (suspend-to-idle) and "disk" (hibernation).
+
+ Writing one of the above strings to this file causes the system
+ to transition into the corresponding state, if available.
+
+ See Documentation/power/states.txt for more information.
+
+What: /sys/power/mem_sleep
+Date: November 2016
+Contact: Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+ The /sys/power/mem_sleep file controls the operating mode of
+ system suspend. Reading from it returns the available modes
+ as "s2idle" (always present), "shallow" and "deep" (present if
+ supported). The mode that will be used on subsequent attempts
+ to suspend the system (by writing "mem" to the /sys/power/state
+ file described above) is enclosed in square brackets.
+
+ Writing one of the above strings to this file causes the mode
+ represented by it to be used on subsequent attempts to suspend
+ the system.
+
+ See Documentation/power/states.txt for more information.
What: /sys/power/disk
Date: September 2006
diff --git a/Documentation/BUG-HUNTING b/Documentation/BUG-HUNTING
deleted file mode 100644
index 65022a87bf17..000000000000
--- a/Documentation/BUG-HUNTING
+++ /dev/null
@@ -1,246 +0,0 @@
-Table of contents
-=================
-
-Last updated: 20 December 2005
-
-Contents
-========
-
-- Introduction
-- Devices not appearing
-- Finding patch that caused a bug
--- Finding using git-bisect
--- Finding it the old way
-- Fixing the bug
-
-Introduction
-============
-
-Always try the latest kernel from kernel.org and build from source. If you are
-not confident in doing that please report the bug to your distribution vendor
-instead of to a kernel developer.
-
-Finding bugs is not always easy. Have a go though. If you can't find it don't
-give up. Report as much as you have found to the relevant maintainer. See
-MAINTAINERS for who that is for the subsystem you have worked on.
-
-Before you submit a bug report read REPORTING-BUGS.
-
-Devices not appearing
-=====================
-
-Often this is caused by udev. Check that first before blaming it on the
-kernel.
-
-Finding patch that caused a bug
-===============================
-
-
-
-Finding using git-bisect
-------------------------
-
-Using the provided tools with git makes finding bugs easy provided the bug is
-reproducible.
-
-Steps to do it:
-- start using git for the kernel source
-- read the man page for git-bisect
-- have fun
-
-Finding it the old way
-----------------------
-
-[Sat Mar 2 10:32:33 PST 1996 KERNEL_BUG-HOWTO lm@sgi.com (Larry McVoy)]
-
-This is how to track down a bug if you know nothing about kernel hacking.
-It's a brute force approach but it works pretty well.
-
-You need:
-
- . A reproducible bug - it has to happen predictably (sorry)
- . All the kernel tar files from a revision that worked to the
- revision that doesn't
-
-You will then do:
-
- . Rebuild a revision that you believe works, install, and verify that.
- . Do a binary search over the kernels to figure out which one
- introduced the bug. I.e., suppose 1.3.28 didn't have the bug, but
- you know that 1.3.69 does. Pick a kernel in the middle and build
- that, like 1.3.50. Build & test; if it works, pick the mid point
- between .50 and .69, else the mid point between .28 and .50.
- . You'll narrow it down to the kernel that introduced the bug. You
- can probably do better than this but it gets tricky.
-
- . Narrow it down to a subdirectory
-
- - Copy kernel that works into "test". Let's say that 3.62 works,
- but 3.63 doesn't. So you diff -r those two kernels and come
- up with a list of directories that changed. For each of those
- directories:
-
- Copy the non-working directory next to the working directory
- as "dir.63".
- One directory at time, try moving the working directory to
- "dir.62" and mv dir.63 dir"time, try
-
- mv dir dir.62
- mv dir.63 dir
- find dir -name '*.[oa]' -print | xargs rm -f
-
- And then rebuild and retest. Assuming that all related
- changes were contained in the sub directory, this should
- isolate the change to a directory.
-
- Problems: changes in header files may have occurred; I've
- found in my case that they were self explanatory - you may
- or may not want to give up when that happens.
-
- . Narrow it down to a file
-
- - You can apply the same technique to each file in the directory,
- hoping that the changes in that file are self contained.
-
- . Narrow it down to a routine
-
- - You can take the old file and the new file and manually create
- a merged file that has
-
- #ifdef VER62
- routine()
- {
- ...
- }
- #else
- routine()
- {
- ...
- }
- #endif
-
- And then walk through that file, one routine at a time and
- prefix it with
-
- #define VER62
- /* both routines here */
- #undef VER62
-
- Then recompile, retest, move the ifdefs until you find the one
- that makes the difference.
-
-Finally, you take all the info that you have, kernel revisions, bug
-description, the extent to which you have narrowed it down, and pass
-that off to whomever you believe is the maintainer of that section.
-A post to linux.dev.kernel isn't such a bad idea if you've done some
-work to narrow it down.
-
-If you get it down to a routine, you'll probably get a fix in 24 hours.
-
-My apologies to Linus and the other kernel hackers for describing this
-brute force approach, it's hardly what a kernel hacker would do. However,
-it does work and it lets non-hackers help fix bugs. And it is cool
-because Linux snapshots will let you do this - something that you can't
-do with vendor supplied releases.
-
-Fixing the bug
-==============
-
-Nobody is going to tell you how to fix bugs. Seriously. You need to work it
-out. But below are some hints on how to use the tools.
-
-To debug a kernel, use objdump and look for the hex offset from the crash
-output to find the valid line of code/assembler. Without debug symbols, you
-will see the assembler code for the routine shown, but if your kernel has
-debug symbols the C code will also be available. (Debug symbols can be enabled
-in the kernel hacking menu of the menu configuration.) For example:
-
- objdump -r -S -l --disassemble net/dccp/ipv4.o
-
-NB.: you need to be at the top level of the kernel tree for this to pick up
-your C files.
-
-If you don't have access to the code you can also debug on some crash dumps
-e.g. crash dump output as shown by Dave Miller.
-
-> EIP is at ip_queue_xmit+0x14/0x4c0
-> ...
-> Code: 44 24 04 e8 6f 05 00 00 e9 e8 fe ff ff 8d 76 00 8d bc 27 00 00
-> 00 00 55 57 56 53 81 ec bc 00 00 00 8b ac 24 d0 00 00 00 8b 5d 08
-> <8b> 83 3c 01 00 00 89 44 24 14 8b 45 28 85 c0 89 44 24 18 0f 85
->
-> Put the bytes into a "foo.s" file like this:
->
-> .text
-> .globl foo
-> foo:
-> .byte .... /* bytes from Code: part of OOPS dump */
->
-> Compile it with "gcc -c -o foo.o foo.s" then look at the output of
-> "objdump --disassemble foo.o".
->
-> Output:
->
-> ip_queue_xmit:
-> push %ebp
-> push %edi
-> push %esi
-> push %ebx
-> sub $0xbc, %esp
-> mov 0xd0(%esp), %ebp ! %ebp = arg0 (skb)
-> mov 0x8(%ebp), %ebx ! %ebx = skb->sk
-> mov 0x13c(%ebx), %eax ! %eax = inet_sk(sk)->opt
-
-In addition, you can use GDB to figure out the exact file and line
-number of the OOPS from the vmlinux file. If you have
-CONFIG_DEBUG_INFO enabled, you can simply copy the EIP value from the
-OOPS:
-
- EIP: 0060:[<c021e50e>] Not tainted VLI
-
-And use GDB to translate that to human-readable form:
-
- gdb vmlinux
- (gdb) l *0xc021e50e
-
-If you don't have CONFIG_DEBUG_INFO enabled, you use the function
-offset from the OOPS:
-
- EIP is at vt_ioctl+0xda8/0x1482
-
-And recompile the kernel with CONFIG_DEBUG_INFO enabled:
-
- make vmlinux
- gdb vmlinux
- (gdb) p vt_ioctl
- (gdb) l *(0x<address of vt_ioctl> + 0xda8)
-or, as one command
- (gdb) l *(vt_ioctl + 0xda8)
-
-If you have a call trace, such as :-
->Call Trace:
-> [<ffffffff8802c8e9>] :jbd:log_wait_commit+0xa3/0xf5
-> [<ffffffff810482d9>] autoremove_wake_function+0x0/0x2e
-> [<ffffffff8802770b>] :jbd:journal_stop+0x1be/0x1ee
-> ...
-this shows the problem in the :jbd: module. You can load that module in gdb
-and list the relevant code.
- gdb fs/jbd/jbd.ko
- (gdb) p log_wait_commit
- (gdb) l *(0x<address> + 0xa3)
-or
- (gdb) l *(log_wait_commit + 0xa3)
-
-
-Another very useful option of the Kernel Hacking section in menuconfig is
-Debug memory allocations. This will help you see whether data has been
-initialised and not set before use etc. To see the values that get assigned
-with this look at mm/slab.c and search for POISON_INUSE. When using this an
-Oops will often show the poisoned data instead of zero which is the default.
-
-Once you have worked out a fix please submit it upstream. After all open
-source is about sharing what you do and don't you want to be recognised for
-your genius?
-
-Please do read Documentation/SubmittingPatches though to help your code get
-accepted.
diff --git a/Documentation/Changes b/Documentation/Changes
index 22797a15dc24..7564ae1682ba 100644..120000
--- a/Documentation/Changes
+++ b/Documentation/Changes
@@ -1,485 +1 @@
-.. _changes:
-
-Minimal requerements to compile the Kernel
-++++++++++++++++++++++++++++++++++++++++++
-
-Intro
-=====
-
-This document is designed to provide a list of the minimum levels of
-software necessary to run the 4.x kernels.
-
-This document is originally based on my "Changes" file for 2.0.x kernels
-and therefore owes credit to the same people as that file (Jared Mauch,
-Axel Boldt, Alessandro Sigala, and countless other users all over the
-'net).
-
-Current Minimal Requirements
-****************************
-
-Upgrade to at **least** these software revisions before thinking you've
-encountered a bug! If you're unsure what version you're currently
-running, the suggested command should tell you.
-
-Again, keep in mind that this list assumes you are already functionally
-running a Linux kernel. Also, not all tools are necessary on all
-systems; obviously, if you don't have any ISDN hardware, for example,
-you probably needn't concern yourself with isdn4k-utils.
-
-====================== =============== ========================================
- Program Minimal version Command to check the version
-====================== =============== ========================================
-GNU C 3.2 gcc --version
-GNU make 3.80 make --version
-binutils 2.12 ld -v
-util-linux 2.10o fdformat --version
-module-init-tools 0.9.10 depmod -V
-e2fsprogs 1.41.4 e2fsck -V
-jfsutils 1.1.3 fsck.jfs -V
-reiserfsprogs 3.6.3 reiserfsck -V
-xfsprogs 2.6.0 xfs_db -V
-squashfs-tools 4.0 mksquashfs -version
-btrfs-progs 0.18 btrfsck
-pcmciautils 004 pccardctl -V
-quota-tools 3.09 quota -V
-PPP 2.4.0 pppd --version
-isdn4k-utils 3.1pre1 isdnctrl 2>&1|grep version
-nfs-utils 1.0.5 showmount --version
-procps 3.2.0 ps --version
-oprofile 0.9 oprofiled --version
-udev 081 udevd --version
-grub 0.93 grub --version || grub-install --version
-mcelog 0.6 mcelog --version
-iptables 1.4.2 iptables -V
-openssl & libcrypto 1.0.0 openssl version
-bc 1.06.95 bc --version
-Sphinx\ [#f1]_ 1.2 sphinx-build --version
-====================== =============== ========================================
-
-.. [#f1] Sphinx is needed only to build the Kernel documentation
-
-Kernel compilation
-******************
-
-GCC
----
-
-The gcc version requirements may vary depending on the type of CPU in your
-computer.
-
-Make
-----
-
-You will need GNU make 3.80 or later to build the kernel.
-
-Binutils
---------
-
-Linux on IA-32 has recently switched from using ``as86`` to using ``gas`` for
-assembling the 16-bit boot code, removing the need for ``as86`` to compile
-your kernel. This change does, however, mean that you need a recent
-release of binutils.
-
-Perl
-----
-
-You will need perl 5 and the following modules: ``Getopt::Long``,
-``Getopt::Std``, ``File::Basename``, and ``File::Find`` to build the kernel.
-
-BC
---
-
-You will need bc to build kernels 3.10 and higher
-
-
-OpenSSL
--------
-
-Module signing and external certificate handling use the OpenSSL program and
-crypto library to do key creation and signature generation.
-
-You will need openssl to build kernels 3.7 and higher if module signing is
-enabled. You will also need openssl development packages to build kernels 4.3
-and higher.
-
-
-System utilities
-****************
-
-Architectural changes
----------------------
-
-DevFS has been obsoleted in favour of udev
-(http://www.kernel.org/pub/linux/utils/kernel/hotplug/)
-
-32-bit UID support is now in place. Have fun!
-
-Linux documentation for functions is transitioning to inline
-documentation via specially-formatted comments near their
-definitions in the source. These comments can be combined with the
-SGML templates in the Documentation/DocBook directory to make DocBook
-files, which can then be converted by DocBook stylesheets to PostScript,
-HTML, PDF files, and several other formats. In order to convert from
-DocBook format to a format of your choice, you'll need to install Jade as
-well as the desired DocBook stylesheets.
-
-Util-linux
-----------
-
-New versions of util-linux provide ``fdisk`` support for larger disks,
-support new options to mount, recognize more supported partition
-types, have a fdformat which works with 2.4 kernels, and similar goodies.
-You'll probably want to upgrade.
-
-Ksymoops
---------
-
-If the unthinkable happens and your kernel oopses, you may need the
-ksymoops tool to decode it, but in most cases you don't.
-It is generally preferred to build the kernel with ``CONFIG_KALLSYMS`` so
-that it produces readable dumps that can be used as-is (this also
-produces better output than ksymoops). If for some reason your kernel
-is not build with ``CONFIG_KALLSYMS`` and you have no way to rebuild and
-reproduce the Oops with that option, then you can still decode that Oops
-with ksymoops.
-
-Module-Init-Tools
------------------
-
-A new module loader is now in the kernel that requires ``module-init-tools``
-to use. It is backward compatible with the 2.4.x series kernels.
-
-Mkinitrd
---------
-
-These changes to the ``/lib/modules`` file tree layout also require that
-mkinitrd be upgraded.
-
-E2fsprogs
----------
-
-The latest version of ``e2fsprogs`` fixes several bugs in fsck and
-debugfs. Obviously, it's a good idea to upgrade.
-
-JFSutils
---------
-
-The ``jfsutils`` package contains the utilities for the file system.
-The following utilities are available:
-
-- ``fsck.jfs`` - initiate replay of the transaction log, and check
- and repair a JFS formatted partition.
-
-- ``mkfs.jfs`` - create a JFS formatted partition.
-
-- other file system utilities are also available in this package.
-
-Reiserfsprogs
--------------
-
-The reiserfsprogs package should be used for reiserfs-3.6.x
-(Linux kernels 2.4.x). It is a combined package and contains working
-versions of ``mkreiserfs``, ``resize_reiserfs``, ``debugreiserfs`` and
-``reiserfsck``. These utils work on both i386 and alpha platforms.
-
-Xfsprogs
---------
-
-The latest version of ``xfsprogs`` contains ``mkfs.xfs``, ``xfs_db``, and the
-``xfs_repair`` utilities, among others, for the XFS filesystem. It is
-architecture independent and any version from 2.0.0 onward should
-work correctly with this version of the XFS kernel code (2.6.0 or
-later is recommended, due to some significant improvements).
-
-PCMCIAutils
------------
-
-PCMCIAutils replaces ``pcmcia-cs``. It properly sets up
-PCMCIA sockets at system startup and loads the appropriate modules
-for 16-bit PCMCIA devices if the kernel is modularized and the hotplug
-subsystem is used.
-
-Quota-tools
------------
-
-Support for 32 bit uid's and gid's is required if you want to use
-the newer version 2 quota format. Quota-tools version 3.07 and
-newer has this support. Use the recommended version or newer
-from the table above.
-
-Intel IA32 microcode
---------------------
-
-A driver has been added to allow updating of Intel IA32 microcode,
-accessible as a normal (misc) character device. If you are not using
-udev you may need to::
-
- mkdir /dev/cpu
- mknod /dev/cpu/microcode c 10 184
- chmod 0644 /dev/cpu/microcode
-
-as root before you can use this. You'll probably also want to
-get the user-space microcode_ctl utility to use with this.
-
-udev
-----
-
-``udev`` is a userspace application for populating ``/dev`` dynamically with
-only entries for devices actually present. ``udev`` replaces the basic
-functionality of devfs, while allowing persistent device naming for
-devices.
-
-FUSE
-----
-
-Needs libfuse 2.4.0 or later. Absolute minimum is 2.3.0 but mount
-options ``direct_io`` and ``kernel_cache`` won't work.
-
-Networking
-**********
-
-General changes
----------------
-
-If you have advanced network configuration needs, you should probably
-consider using the network tools from ip-route2.
-
-Packet Filter / NAT
--------------------
-The packet filtering and NAT code uses the same tools like the previous 2.4.x
-kernel series (iptables). It still includes backwards-compatibility modules
-for 2.2.x-style ipchains and 2.0.x-style ipfwadm.
-
-PPP
----
-
-The PPP driver has been restructured to support multilink and to
-enable it to operate over diverse media layers. If you use PPP,
-upgrade pppd to at least 2.4.0.
-
-If you are not using udev, you must have the device file /dev/ppp
-which can be made by::
-
- mknod /dev/ppp c 108 0
-
-as root.
-
-Isdn4k-utils
-------------
-
-Due to changes in the length of the phone number field, isdn4k-utils
-needs to be recompiled or (preferably) upgraded.
-
-NFS-utils
----------
-
-In ancient (2.4 and earlier) kernels, the nfs server needed to know
-about any client that expected to be able to access files via NFS. This
-information would be given to the kernel by ``mountd`` when the client
-mounted the filesystem, or by ``exportfs`` at system startup. exportfs
-would take information about active clients from ``/var/lib/nfs/rmtab``.
-
-This approach is quite fragile as it depends on rmtab being correct
-which is not always easy, particularly when trying to implement
-fail-over. Even when the system is working well, ``rmtab`` suffers from
-getting lots of old entries that never get removed.
-
-With modern kernels we have the option of having the kernel tell mountd
-when it gets a request from an unknown host, and mountd can give
-appropriate export information to the kernel. This removes the
-dependency on ``rmtab`` and means that the kernel only needs to know about
-currently active clients.
-
-To enable this new functionality, you need to::
-
- mount -t nfsd nfsd /proc/fs/nfsd
-
-before running exportfs or mountd. It is recommended that all NFS
-services be protected from the internet-at-large by a firewall where
-that is possible.
-
-mcelog
-------
-
-On x86 kernels the mcelog utility is needed to process and log machine check
-events when ``CONFIG_X86_MCE`` is enabled. Machine check events are errors
-reported by the CPU. Processing them is strongly encouraged.
-
-Kernel documentation
-********************
-
-Sphinx
-------
-
-The ReST markups currently used by the Documentation/ files are meant to be
-built with ``Sphinx`` version 1.2 or upper. If you're desiring to build
-PDF outputs, it is recommended to use version 1.4.6.
-
-.. note::
-
- Please notice that, for PDF and LaTeX output, you'll also need ``XeLaTeX``
- version 3.14159265. Depending on the distribution, you may also need
- to install a series of ``texlive`` packages that provide the minimal
- set of functionalities required for ``XeLaTex`` to work.
-
-Other tools
------------
-
-In order to produce documentation from DocBook, you'll also need ``xmlto``.
-Please notice, however, that we're currently migrating all documents to use
-``Sphinx``.
-
-Getting updated software
-========================
-
-Kernel compilation
-******************
-
-gcc
----
-
-- <ftp://ftp.gnu.org/gnu/gcc/>
-
-Make
-----
-
-- <ftp://ftp.gnu.org/gnu/make/>
-
-Binutils
---------
-
-- <ftp://ftp.kernel.org/pub/linux/devel/binutils/>
-
-OpenSSL
--------
-
-- <https://www.openssl.org/>
-
-System utilities
-****************
-
-Util-linux
-----------
-
-- <ftp://ftp.kernel.org/pub/linux/utils/util-linux/>
-
-Ksymoops
---------
-
-- <ftp://ftp.kernel.org/pub/linux/utils/kernel/ksymoops/v2.4/>
-
-Module-Init-Tools
------------------
-
-- <ftp://ftp.kernel.org/pub/linux/kernel/people/rusty/modules/>
-
-Mkinitrd
---------
-
-- <https://code.launchpad.net/initrd-tools/main>
-
-E2fsprogs
----------
-
-- <http://prdownloads.sourceforge.net/e2fsprogs/e2fsprogs-1.29.tar.gz>
-
-JFSutils
---------
-
-- <http://jfs.sourceforge.net/>
-
-Reiserfsprogs
--------------
-
-- <http://www.kernel.org/pub/linux/utils/fs/reiserfs/>
-
-Xfsprogs
---------
-
-- <ftp://oss.sgi.com/projects/xfs/>
-
-Pcmciautils
------------
-
-- <ftp://ftp.kernel.org/pub/linux/utils/kernel/pcmcia/>
-
-Quota-tools
------------
-
-- <http://sourceforge.net/projects/linuxquota/>
-
-DocBook Stylesheets
--------------------
-
-- <http://sourceforge.net/projects/docbook/files/docbook-dsssl/>
-
-XMLTO XSLT Frontend
--------------------
-
-- <http://cyberelk.net/tim/xmlto/>
-
-Intel P6 microcode
-------------------
-
-- <https://downloadcenter.intel.com/>
-
-udev
-----
-
-- <http://www.freedesktop.org/software/systemd/man/udev.html>
-
-FUSE
-----
-
-- <http://sourceforge.net/projects/fuse>
-
-mcelog
-------
-
-- <http://www.mcelog.org/>
-
-Networking
-**********
-
-PPP
----
-
-- <ftp://ftp.samba.org/pub/ppp/>
-
-Isdn4k-utils
-------------
-
-- <ftp://ftp.isdn4linux.de/pub/isdn4linux/utils/>
-
-NFS-utils
----------
-
-- <http://sourceforge.net/project/showfiles.php?group_id=14>
-
-Iptables
---------
-
-- <http://www.iptables.org/downloads.html>
-
-Ip-route2
----------
-
-- <https://www.kernel.org/pub/linux/utils/net/iproute2/>
-
-OProfile
---------
-
-- <http://oprofile.sf.net/download/>
-
-NFS-Utils
----------
-
-- <http://nfs.sourceforge.net/>
-
-Kernel documentation
-********************
-
-Sphinx
-------
-
-- <http://www.sphinx-doc.org/>
+process/changes.rst \ No newline at end of file
diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle
index 9c61c039ccd9..320983ca114e 100644
--- a/Documentation/CodingStyle
+++ b/Documentation/CodingStyle
@@ -1,1062 +1 @@
-.. _codingstyle:
-
-Linux kernel coding style
-=========================
-
-This is a short document describing the preferred coding style for the
-linux kernel. Coding style is very personal, and I won't **force** my
-views on anybody, but this is what goes for anything that I have to be
-able to maintain, and I'd prefer it for most other things too. Please
-at least consider the points made here.
-
-First off, I'd suggest printing out a copy of the GNU coding standards,
-and NOT read it. Burn them, it's a great symbolic gesture.
-
-Anyway, here goes:
-
-
-1) Indentation
---------------
-
-Tabs are 8 characters, and thus indentations are also 8 characters.
-There are heretic movements that try to make indentations 4 (or even 2!)
-characters deep, and that is akin to trying to define the value of PI to
-be 3.
-
-Rationale: The whole idea behind indentation is to clearly define where
-a block of control starts and ends. Especially when you've been looking
-at your screen for 20 straight hours, you'll find it a lot easier to see
-how the indentation works if you have large indentations.
-
-Now, some people will claim that having 8-character indentations makes
-the code move too far to the right, and makes it hard to read on a
-80-character terminal screen. The answer to that is that if you need
-more than 3 levels of indentation, you're screwed anyway, and should fix
-your program.
-
-In short, 8-char indents make things easier to read, and have the added
-benefit of warning you when you're nesting your functions too deep.
-Heed that warning.
-
-The preferred way to ease multiple indentation levels in a switch statement is
-to align the ``switch`` and its subordinate ``case`` labels in the same column
-instead of ``double-indenting`` the ``case`` labels. E.g.:
-
-.. code-block:: c
-
- switch (suffix) {
- case 'G':
- case 'g':
- mem <<= 30;
- break;
- case 'M':
- case 'm':
- mem <<= 20;
- break;
- case 'K':
- case 'k':
- mem <<= 10;
- /* fall through */
- default:
- break;
- }
-
-Don't put multiple statements on a single line unless you have
-something to hide:
-
-.. code-block:: c
-
- if (condition) do_this;
- do_something_everytime;
-
-Don't put multiple assignments on a single line either. Kernel coding style
-is super simple. Avoid tricky expressions.
-
-Outside of comments, documentation and except in Kconfig, spaces are never
-used for indentation, and the above example is deliberately broken.
-
-Get a decent editor and don't leave whitespace at the end of lines.
-
-
-2) Breaking long lines and strings
-----------------------------------
-
-Coding style is all about readability and maintainability using commonly
-available tools.
-
-The limit on the length of lines is 80 columns and this is a strongly
-preferred limit.
-
-Statements longer than 80 columns will be broken into sensible chunks, unless
-exceeding 80 columns significantly increases readability and does not hide
-information. Descendants are always substantially shorter than the parent and
-are placed substantially to the right. The same applies to function headers
-with a long argument list. However, never break user-visible strings such as
-printk messages, because that breaks the ability to grep for them.
-
-
-3) Placing Braces and Spaces
-----------------------------
-
-The other issue that always comes up in C styling is the placement of
-braces. Unlike the indent size, there are few technical reasons to
-choose one placement strategy over the other, but the preferred way, as
-shown to us by the prophets Kernighan and Ritchie, is to put the opening
-brace last on the line, and put the closing brace first, thusly:
-
-.. code-block:: c
-
- if (x is true) {
- we do y
- }
-
-This applies to all non-function statement blocks (if, switch, for,
-while, do). E.g.:
-
-.. code-block:: c
-
- switch (action) {
- case KOBJ_ADD:
- return "add";
- case KOBJ_REMOVE:
- return "remove";
- case KOBJ_CHANGE:
- return "change";
- default:
- return NULL;
- }
-
-However, there is one special case, namely functions: they have the
-opening brace at the beginning of the next line, thus:
-
-.. code-block:: c
-
- int function(int x)
- {
- body of function
- }
-
-Heretic people all over the world have claimed that this inconsistency
-is ... well ... inconsistent, but all right-thinking people know that
-(a) K&R are **right** and (b) K&R are right. Besides, functions are
-special anyway (you can't nest them in C).
-
-Note that the closing brace is empty on a line of its own, **except** in
-the cases where it is followed by a continuation of the same statement,
-ie a ``while`` in a do-statement or an ``else`` in an if-statement, like
-this:
-
-.. code-block:: c
-
- do {
- body of do-loop
- } while (condition);
-
-and
-
-.. code-block:: c
-
- if (x == y) {
- ..
- } else if (x > y) {
- ...
- } else {
- ....
- }
-
-Rationale: K&R.
-
-Also, note that this brace-placement also minimizes the number of empty
-(or almost empty) lines, without any loss of readability. Thus, as the
-supply of new-lines on your screen is not a renewable resource (think
-25-line terminal screens here), you have more empty lines to put
-comments on.
-
-Do not unnecessarily use braces where a single statement will do.
-
-.. code-block:: c
-
- if (condition)
- action();
-
-and
-
-.. code-block:: none
-
- if (condition)
- do_this();
- else
- do_that();
-
-This does not apply if only one branch of a conditional statement is a single
-statement; in the latter case use braces in both branches:
-
-.. code-block:: c
-
- if (condition) {
- do_this();
- do_that();
- } else {
- otherwise();
- }
-
-3.1) Spaces
-***********
-
-Linux kernel style for use of spaces depends (mostly) on
-function-versus-keyword usage. Use a space after (most) keywords. The
-notable exceptions are sizeof, typeof, alignof, and __attribute__, which look
-somewhat like functions (and are usually used with parentheses in Linux,
-although they are not required in the language, as in: ``sizeof info`` after
-``struct fileinfo info;`` is declared).
-
-So use a space after these keywords::
-
- if, switch, case, for, do, while
-
-but not with sizeof, typeof, alignof, or __attribute__. E.g.,
-
-.. code-block:: c
-
-
- s = sizeof(struct file);
-
-Do not add spaces around (inside) parenthesized expressions. This example is
-**bad**:
-
-.. code-block:: c
-
-
- s = sizeof( struct file );
-
-When declaring pointer data or a function that returns a pointer type, the
-preferred use of ``*`` is adjacent to the data name or function name and not
-adjacent to the type name. Examples:
-
-.. code-block:: c
-
-
- char *linux_banner;
- unsigned long long memparse(char *ptr, char **retptr);
- char *match_strdup(substring_t *s);
-
-Use one space around (on each side of) most binary and ternary operators,
-such as any of these::
-
- = + - < > * / % | & ^ <= >= == != ? :
-
-but no space after unary operators::
-
- & * + - ~ ! sizeof typeof alignof __attribute__ defined
-
-no space before the postfix increment & decrement unary operators::
-
- ++ --
-
-no space after the prefix increment & decrement unary operators::
-
- ++ --
-
-and no space around the ``.`` and ``->`` structure member operators.
-
-Do not leave trailing whitespace at the ends of lines. Some editors with
-``smart`` indentation will insert whitespace at the beginning of new lines as
-appropriate, so you can start typing the next line of code right away.
-However, some such editors do not remove the whitespace if you end up not
-putting a line of code there, such as if you leave a blank line. As a result,
-you end up with lines containing trailing whitespace.
-
-Git will warn you about patches that introduce trailing whitespace, and can
-optionally strip the trailing whitespace for you; however, if applying a series
-of patches, this may make later patches in the series fail by changing their
-context lines.
-
-
-4) Naming
----------
-
-C is a Spartan language, and so should your naming be. Unlike Modula-2
-and Pascal programmers, C programmers do not use cute names like
-ThisVariableIsATemporaryCounter. A C programmer would call that
-variable ``tmp``, which is much easier to write, and not the least more
-difficult to understand.
-
-HOWEVER, while mixed-case names are frowned upon, descriptive names for
-global variables are a must. To call a global function ``foo`` is a
-shooting offense.
-
-GLOBAL variables (to be used only if you **really** need them) need to
-have descriptive names, as do global functions. If you have a function
-that counts the number of active users, you should call that
-``count_active_users()`` or similar, you should **not** call it ``cntusr()``.
-
-Encoding the type of a function into the name (so-called Hungarian
-notation) is brain damaged - the compiler knows the types anyway and can
-check those, and it only confuses the programmer. No wonder MicroSoft
-makes buggy programs.
-
-LOCAL variable names should be short, and to the point. If you have
-some random integer loop counter, it should probably be called ``i``.
-Calling it ``loop_counter`` is non-productive, if there is no chance of it
-being mis-understood. Similarly, ``tmp`` can be just about any type of
-variable that is used to hold a temporary value.
-
-If you are afraid to mix up your local variable names, you have another
-problem, which is called the function-growth-hormone-imbalance syndrome.
-See chapter 6 (Functions).
-
-
-5) Typedefs
------------
-
-Please don't use things like ``vps_t``.
-It's a **mistake** to use typedef for structures and pointers. When you see a
-
-.. code-block:: c
-
-
- vps_t a;
-
-in the source, what does it mean?
-In contrast, if it says
-
-.. code-block:: c
-
- struct virtual_container *a;
-
-you can actually tell what ``a`` is.
-
-Lots of people think that typedefs ``help readability``. Not so. They are
-useful only for:
-
- (a) totally opaque objects (where the typedef is actively used to **hide**
- what the object is).
-
- Example: ``pte_t`` etc. opaque objects that you can only access using
- the proper accessor functions.
-
- .. note::
-
- Opaqueness and ``accessor functions`` are not good in themselves.
- The reason we have them for things like pte_t etc. is that there
- really is absolutely **zero** portably accessible information there.
-
- (b) Clear integer types, where the abstraction **helps** avoid confusion
- whether it is ``int`` or ``long``.
-
- u8/u16/u32 are perfectly fine typedefs, although they fit into
- category (d) better than here.
-
- .. note::
-
- Again - there needs to be a **reason** for this. If something is
- ``unsigned long``, then there's no reason to do
-
- typedef unsigned long myflags_t;
-
- but if there is a clear reason for why it under certain circumstances
- might be an ``unsigned int`` and under other configurations might be
- ``unsigned long``, then by all means go ahead and use a typedef.
-
- (c) when you use sparse to literally create a **new** type for
- type-checking.
-
- (d) New types which are identical to standard C99 types, in certain
- exceptional circumstances.
-
- Although it would only take a short amount of time for the eyes and
- brain to become accustomed to the standard types like ``uint32_t``,
- some people object to their use anyway.
-
- Therefore, the Linux-specific ``u8/u16/u32/u64`` types and their
- signed equivalents which are identical to standard types are
- permitted -- although they are not mandatory in new code of your
- own.
-
- When editing existing code which already uses one or the other set
- of types, you should conform to the existing choices in that code.
-
- (e) Types safe for use in userspace.
-
- In certain structures which are visible to userspace, we cannot
- require C99 types and cannot use the ``u32`` form above. Thus, we
- use __u32 and similar types in all structures which are shared
- with userspace.
-
-Maybe there are other cases too, but the rule should basically be to NEVER
-EVER use a typedef unless you can clearly match one of those rules.
-
-In general, a pointer, or a struct that has elements that can reasonably
-be directly accessed should **never** be a typedef.
-
-
-6) Functions
-------------
-
-Functions should be short and sweet, and do just one thing. They should
-fit on one or two screenfuls of text (the ISO/ANSI screen size is 80x24,
-as we all know), and do one thing and do that well.
-
-The maximum length of a function is inversely proportional to the
-complexity and indentation level of that function. So, if you have a
-conceptually simple function that is just one long (but simple)
-case-statement, where you have to do lots of small things for a lot of
-different cases, it's OK to have a longer function.
-
-However, if you have a complex function, and you suspect that a
-less-than-gifted first-year high-school student might not even
-understand what the function is all about, you should adhere to the
-maximum limits all the more closely. Use helper functions with
-descriptive names (you can ask the compiler to in-line them if you think
-it's performance-critical, and it will probably do a better job of it
-than you would have done).
-
-Another measure of the function is the number of local variables. They
-shouldn't exceed 5-10, or you're doing something wrong. Re-think the
-function, and split it into smaller pieces. A human brain can
-generally easily keep track of about 7 different things, anything more
-and it gets confused. You know you're brilliant, but maybe you'd like
-to understand what you did 2 weeks from now.
-
-In source files, separate functions with one blank line. If the function is
-exported, the **EXPORT** macro for it should follow immediately after the
-closing function brace line. E.g.:
-
-.. code-block:: c
-
- int system_is_up(void)
- {
- return system_state == SYSTEM_RUNNING;
- }
- EXPORT_SYMBOL(system_is_up);
-
-In function prototypes, include parameter names with their data types.
-Although this is not required by the C language, it is preferred in Linux
-because it is a simple way to add valuable information for the reader.
-
-
-7) Centralized exiting of functions
------------------------------------
-
-Albeit deprecated by some people, the equivalent of the goto statement is
-used frequently by compilers in form of the unconditional jump instruction.
-
-The goto statement comes in handy when a function exits from multiple
-locations and some common work such as cleanup has to be done. If there is no
-cleanup needed then just return directly.
-
-Choose label names which say what the goto does or why the goto exists. An
-example of a good name could be ``out_free_buffer:`` if the goto frees ``buffer``.
-Avoid using GW-BASIC names like ``err1:`` and ``err2:``, as you would have to
-renumber them if you ever add or remove exit paths, and they make correctness
-difficult to verify anyway.
-
-The rationale for using gotos is:
-
-- unconditional statements are easier to understand and follow
-- nesting is reduced
-- errors by not updating individual exit points when making
- modifications are prevented
-- saves the compiler work to optimize redundant code away ;)
-
-.. code-block:: c
-
- int fun(int a)
- {
- int result = 0;
- char *buffer;
-
- buffer = kmalloc(SIZE, GFP_KERNEL);
- if (!buffer)
- return -ENOMEM;
-
- if (condition1) {
- while (loop1) {
- ...
- }
- result = 1;
- goto out_buffer;
- }
- ...
- out_free_buffer:
- kfree(buffer);
- return result;
- }
-
-A common type of bug to be aware of is ``one err bugs`` which look like this:
-
-.. code-block:: c
-
- err:
- kfree(foo->bar);
- kfree(foo);
- return ret;
-
-The bug in this code is that on some exit paths ``foo`` is NULL. Normally the
-fix for this is to split it up into two error labels ``err_free_bar:`` and
-``err_free_foo:``:
-
-.. code-block:: c
-
- err_free_bar:
- kfree(foo->bar);
- err_free_foo:
- kfree(foo);
- return ret;
-
-Ideally you should simulate errors to test all exit paths.
-
-
-8) Commenting
--------------
-
-Comments are good, but there is also a danger of over-commenting. NEVER
-try to explain HOW your code works in a comment: it's much better to
-write the code so that the **working** is obvious, and it's a waste of
-time to explain badly written code.
-
-Generally, you want your comments to tell WHAT your code does, not HOW.
-Also, try to avoid putting comments inside a function body: if the
-function is so complex that you need to separately comment parts of it,
-you should probably go back to chapter 6 for a while. You can make
-small comments to note or warn about something particularly clever (or
-ugly), but try to avoid excess. Instead, put the comments at the head
-of the function, telling people what it does, and possibly WHY it does
-it.
-
-When commenting the kernel API functions, please use the kernel-doc format.
-See the files Documentation/kernel-documentation.rst and scripts/kernel-doc
-for details.
-
-The preferred style for long (multi-line) comments is:
-
-.. code-block:: c
-
- /*
- * This is the preferred style for multi-line
- * comments in the Linux kernel source code.
- * Please use it consistently.
- *
- * Description: A column of asterisks on the left side,
- * with beginning and ending almost-blank lines.
- */
-
-For files in net/ and drivers/net/ the preferred style for long (multi-line)
-comments is a little different.
-
-.. code-block:: c
-
- /* The preferred comment style for files in net/ and drivers/net
- * looks like this.
- *
- * It is nearly the same as the generally preferred comment style,
- * but there is no initial almost-blank line.
- */
-
-It's also important to comment data, whether they are basic types or derived
-types. To this end, use just one data declaration per line (no commas for
-multiple data declarations). This leaves you room for a small comment on each
-item, explaining its use.
-
-
-9) You've made a mess of it
----------------------------
-
-That's OK, we all do. You've probably been told by your long-time Unix
-user helper that ``GNU emacs`` automatically formats the C sources for
-you, and you've noticed that yes, it does do that, but the defaults it
-uses are less than desirable (in fact, they are worse than random
-typing - an infinite number of monkeys typing into GNU emacs would never
-make a good program).
-
-So, you can either get rid of GNU emacs, or change it to use saner
-values. To do the latter, you can stick the following in your .emacs file:
-
-.. code-block:: none
-
- (defun c-lineup-arglist-tabs-only (ignored)
- "Line up argument lists by tabs, not spaces"
- (let* ((anchor (c-langelem-pos c-syntactic-element))
- (column (c-langelem-2nd-pos c-syntactic-element))
- (offset (- (1+ column) anchor))
- (steps (floor offset c-basic-offset)))
- (* (max steps 1)
- c-basic-offset)))
-
- (add-hook 'c-mode-common-hook
- (lambda ()
- ;; Add kernel style
- (c-add-style
- "linux-tabs-only"
- '("linux" (c-offsets-alist
- (arglist-cont-nonempty
- c-lineup-gcc-asm-reg
- c-lineup-arglist-tabs-only))))))
-
- (add-hook 'c-mode-hook
- (lambda ()
- (let ((filename (buffer-file-name)))
- ;; Enable kernel mode for the appropriate files
- (when (and filename
- (string-match (expand-file-name "~/src/linux-trees")
- filename))
- (setq indent-tabs-mode t)
- (setq show-trailing-whitespace t)
- (c-set-style "linux-tabs-only")))))
-
-This will make emacs go better with the kernel coding style for C
-files below ``~/src/linux-trees``.
-
-But even if you fail in getting emacs to do sane formatting, not
-everything is lost: use ``indent``.
-
-Now, again, GNU indent has the same brain-dead settings that GNU emacs
-has, which is why you need to give it a few command line options.
-However, that's not too bad, because even the makers of GNU indent
-recognize the authority of K&R (the GNU people aren't evil, they are
-just severely misguided in this matter), so you just give indent the
-options ``-kr -i8`` (stands for ``K&R, 8 character indents``), or use
-``scripts/Lindent``, which indents in the latest style.
-
-``indent`` has a lot of options, and especially when it comes to comment
-re-formatting you may want to take a look at the man page. But
-remember: ``indent`` is not a fix for bad programming.
-
-
-10) Kconfig configuration files
--------------------------------
-
-For all of the Kconfig* configuration files throughout the source tree,
-the indentation is somewhat different. Lines under a ``config`` definition
-are indented with one tab, while help text is indented an additional two
-spaces. Example::
-
- config AUDIT
- bool "Auditing support"
- depends on NET
- help
- Enable auditing infrastructure that can be used with another
- kernel subsystem, such as SELinux (which requires this for
- logging of avc messages output). Does not do system-call
- auditing without CONFIG_AUDITSYSCALL.
-
-Seriously dangerous features (such as write support for certain
-filesystems) should advertise this prominently in their prompt string::
-
- config ADFS_FS_RW
- bool "ADFS write support (DANGEROUS)"
- depends on ADFS_FS
- ...
-
-For full documentation on the configuration files, see the file
-Documentation/kbuild/kconfig-language.txt.
-
-
-11) Data structures
--------------------
-
-Data structures that have visibility outside the single-threaded
-environment they are created and destroyed in should always have
-reference counts. In the kernel, garbage collection doesn't exist (and
-outside the kernel garbage collection is slow and inefficient), which
-means that you absolutely **have** to reference count all your uses.
-
-Reference counting means that you can avoid locking, and allows multiple
-users to have access to the data structure in parallel - and not having
-to worry about the structure suddenly going away from under them just
-because they slept or did something else for a while.
-
-Note that locking is **not** a replacement for reference counting.
-Locking is used to keep data structures coherent, while reference
-counting is a memory management technique. Usually both are needed, and
-they are not to be confused with each other.
-
-Many data structures can indeed have two levels of reference counting,
-when there are users of different ``classes``. The subclass count counts
-the number of subclass users, and decrements the global count just once
-when the subclass count goes to zero.
-
-Examples of this kind of ``multi-level-reference-counting`` can be found in
-memory management (``struct mm_struct``: mm_users and mm_count), and in
-filesystem code (``struct super_block``: s_count and s_active).
-
-Remember: if another thread can find your data structure, and you don't
-have a reference count on it, you almost certainly have a bug.
-
-
-12) Macros, Enums and RTL
--------------------------
-
-Names of macros defining constants and labels in enums are capitalized.
-
-.. code-block:: c
-
- #define CONSTANT 0x12345
-
-Enums are preferred when defining several related constants.
-
-CAPITALIZED macro names are appreciated but macros resembling functions
-may be named in lower case.
-
-Generally, inline functions are preferable to macros resembling functions.
-
-Macros with multiple statements should be enclosed in a do - while block:
-
-.. code-block:: c
-
- #define macrofun(a, b, c) \
- do { \
- if (a == 5) \
- do_this(b, c); \
- } while (0)
-
-Things to avoid when using macros:
-
-1) macros that affect control flow:
-
-.. code-block:: c
-
- #define FOO(x) \
- do { \
- if (blah(x) < 0) \
- return -EBUGGERED; \
- } while (0)
-
-is a **very** bad idea. It looks like a function call but exits the ``calling``
-function; don't break the internal parsers of those who will read the code.
-
-2) macros that depend on having a local variable with a magic name:
-
-.. code-block:: c
-
- #define FOO(val) bar(index, val)
-
-might look like a good thing, but it's confusing as hell when one reads the
-code and it's prone to breakage from seemingly innocent changes.
-
-3) macros with arguments that are used as l-values: FOO(x) = y; will
-bite you if somebody e.g. turns FOO into an inline function.
-
-4) forgetting about precedence: macros defining constants using expressions
-must enclose the expression in parentheses. Beware of similar issues with
-macros using parameters.
-
-.. code-block:: c
-
- #define CONSTANT 0x4000
- #define CONSTEXP (CONSTANT | 3)
-
-5) namespace collisions when defining local variables in macros resembling
-functions:
-
-.. code-block:: c
-
- #define FOO(x) \
- ({ \
- typeof(x) ret; \
- ret = calc_ret(x); \
- (ret); \
- })
-
-ret is a common name for a local variable - __foo_ret is less likely
-to collide with an existing variable.
-
-The cpp manual deals with macros exhaustively. The gcc internals manual also
-covers RTL which is used frequently with assembly language in the kernel.
-
-
-13) Printing kernel messages
-----------------------------
-
-Kernel developers like to be seen as literate. Do mind the spelling
-of kernel messages to make a good impression. Do not use crippled
-words like ``dont``; use ``do not`` or ``don't`` instead. Make the messages
-concise, clear, and unambiguous.
-
-Kernel messages do not have to be terminated with a period.
-
-Printing numbers in parentheses (%d) adds no value and should be avoided.
-
-There are a number of driver model diagnostic macros in <linux/device.h>
-which you should use to make sure messages are matched to the right device
-and driver, and are tagged with the right level: dev_err(), dev_warn(),
-dev_info(), and so forth. For messages that aren't associated with a
-particular device, <linux/printk.h> defines pr_notice(), pr_info(),
-pr_warn(), pr_err(), etc.
-
-Coming up with good debugging messages can be quite a challenge; and once
-you have them, they can be a huge help for remote troubleshooting. However
-debug message printing is handled differently than printing other non-debug
-messages. While the other pr_XXX() functions print unconditionally,
-pr_debug() does not; it is compiled out by default, unless either DEBUG is
-defined or CONFIG_DYNAMIC_DEBUG is set. That is true for dev_dbg() also,
-and a related convention uses VERBOSE_DEBUG to add dev_vdbg() messages to
-the ones already enabled by DEBUG.
-
-Many subsystems have Kconfig debug options to turn on -DDEBUG in the
-corresponding Makefile; in other cases specific files #define DEBUG. And
-when a debug message should be unconditionally printed, such as if it is
-already inside a debug-related #ifdef section, printk(KERN_DEBUG ...) can be
-used.
-
-
-14) Allocating memory
----------------------
-
-The kernel provides the following general purpose memory allocators:
-kmalloc(), kzalloc(), kmalloc_array(), kcalloc(), vmalloc(), and
-vzalloc(). Please refer to the API documentation for further information
-about them.
-
-The preferred form for passing a size of a struct is the following:
-
-.. code-block:: c
-
- p = kmalloc(sizeof(*p), ...);
-
-The alternative form where struct name is spelled out hurts readability and
-introduces an opportunity for a bug when the pointer variable type is changed
-but the corresponding sizeof that is passed to a memory allocator is not.
-
-Casting the return value which is a void pointer is redundant. The conversion
-from void pointer to any other pointer type is guaranteed by the C programming
-language.
-
-The preferred form for allocating an array is the following:
-
-.. code-block:: c
-
- p = kmalloc_array(n, sizeof(...), ...);
-
-The preferred form for allocating a zeroed array is the following:
-
-.. code-block:: c
-
- p = kcalloc(n, sizeof(...), ...);
-
-Both forms check for overflow on the allocation size n * sizeof(...),
-and return NULL if that occurred.
-
-
-15) The inline disease
-----------------------
-
-There appears to be a common misperception that gcc has a magic "make me
-faster" speedup option called ``inline``. While the use of inlines can be
-appropriate (for example as a means of replacing macros, see Chapter 12), it
-very often is not. Abundant use of the inline keyword leads to a much bigger
-kernel, which in turn slows the system as a whole down, due to a bigger
-icache footprint for the CPU and simply because there is less memory
-available for the pagecache. Just think about it; a pagecache miss causes a
-disk seek, which easily takes 5 milliseconds. There are a LOT of cpu cycles
-that can go into these 5 milliseconds.
-
-A reasonable rule of thumb is to not put inline at functions that have more
-than 3 lines of code in them. An exception to this rule are the cases where
-a parameter is known to be a compiletime constant, and as a result of this
-constantness you *know* the compiler will be able to optimize most of your
-function away at compile time. For a good example of this later case, see
-the kmalloc() inline function.
-
-Often people argue that adding inline to functions that are static and used
-only once is always a win since there is no space tradeoff. While this is
-technically correct, gcc is capable of inlining these automatically without
-help, and the maintenance issue of removing the inline when a second user
-appears outweighs the potential value of the hint that tells gcc to do
-something it would have done anyway.
-
-
-16) Function return values and names
-------------------------------------
-
-Functions can return values of many different kinds, and one of the
-most common is a value indicating whether the function succeeded or
-failed. Such a value can be represented as an error-code integer
-(-Exxx = failure, 0 = success) or a ``succeeded`` boolean (0 = failure,
-non-zero = success).
-
-Mixing up these two sorts of representations is a fertile source of
-difficult-to-find bugs. If the C language included a strong distinction
-between integers and booleans then the compiler would find these mistakes
-for us... but it doesn't. To help prevent such bugs, always follow this
-convention::
-
- If the name of a function is an action or an imperative command,
- the function should return an error-code integer. If the name
- is a predicate, the function should return a "succeeded" boolean.
-
-For example, ``add work`` is a command, and the add_work() function returns 0
-for success or -EBUSY for failure. In the same way, ``PCI device present`` is
-a predicate, and the pci_dev_present() function returns 1 if it succeeds in
-finding a matching device or 0 if it doesn't.
-
-All EXPORTed functions must respect this convention, and so should all
-public functions. Private (static) functions need not, but it is
-recommended that they do.
-
-Functions whose return value is the actual result of a computation, rather
-than an indication of whether the computation succeeded, are not subject to
-this rule. Generally they indicate failure by returning some out-of-range
-result. Typical examples would be functions that return pointers; they use
-NULL or the ERR_PTR mechanism to report failure.
-
-
-17) Don't re-invent the kernel macros
--------------------------------------
-
-The header file include/linux/kernel.h contains a number of macros that
-you should use, rather than explicitly coding some variant of them yourself.
-For example, if you need to calculate the length of an array, take advantage
-of the macro
-
-.. code-block:: c
-
- #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
-
-Similarly, if you need to calculate the size of some structure member, use
-
-.. code-block:: c
-
- #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
-
-There are also min() and max() macros that do strict type checking if you
-need them. Feel free to peruse that header file to see what else is already
-defined that you shouldn't reproduce in your code.
-
-
-18) Editor modelines and other cruft
-------------------------------------
-
-Some editors can interpret configuration information embedded in source files,
-indicated with special markers. For example, emacs interprets lines marked
-like this:
-
-.. code-block:: c
-
- -*- mode: c -*-
-
-Or like this:
-
-.. code-block:: c
-
- /*
- Local Variables:
- compile-command: "gcc -DMAGIC_DEBUG_FLAG foo.c"
- End:
- */
-
-Vim interprets markers that look like this:
-
-.. code-block:: c
-
- /* vim:set sw=8 noet */
-
-Do not include any of these in source files. People have their own personal
-editor configurations, and your source files should not override them. This
-includes markers for indentation and mode configuration. People may use their
-own custom mode, or may have some other magic method for making indentation
-work correctly.
-
-
-19) Inline assembly
--------------------
-
-In architecture-specific code, you may need to use inline assembly to interface
-with CPU or platform functionality. Don't hesitate to do so when necessary.
-However, don't use inline assembly gratuitously when C can do the job. You can
-and should poke hardware from C when possible.
-
-Consider writing simple helper functions that wrap common bits of inline
-assembly, rather than repeatedly writing them with slight variations. Remember
-that inline assembly can use C parameters.
-
-Large, non-trivial assembly functions should go in .S files, with corresponding
-C prototypes defined in C header files. The C prototypes for assembly
-functions should use ``asmlinkage``.
-
-You may need to mark your asm statement as volatile, to prevent GCC from
-removing it if GCC doesn't notice any side effects. You don't always need to
-do so, though, and doing so unnecessarily can limit optimization.
-
-When writing a single inline assembly statement containing multiple
-instructions, put each instruction on a separate line in a separate quoted
-string, and end each string except the last with \n\t to properly indent the
-next instruction in the assembly output:
-
-.. code-block:: c
-
- asm ("magic %reg1, #42\n\t"
- "more_magic %reg2, %reg3"
- : /* outputs */ : /* inputs */ : /* clobbers */);
-
-
-20) Conditional Compilation
----------------------------
-
-Wherever possible, don't use preprocessor conditionals (#if, #ifdef) in .c
-files; doing so makes code harder to read and logic harder to follow. Instead,
-use such conditionals in a header file defining functions for use in those .c
-files, providing no-op stub versions in the #else case, and then call those
-functions unconditionally from .c files. The compiler will avoid generating
-any code for the stub calls, producing identical results, but the logic will
-remain easy to follow.
-
-Prefer to compile out entire functions, rather than portions of functions or
-portions of expressions. Rather than putting an ifdef in an expression, factor
-out part or all of the expression into a separate helper function and apply the
-conditional to that function.
-
-If you have a function or variable which may potentially go unused in a
-particular configuration, and the compiler would warn about its definition
-going unused, mark the definition as __maybe_unused rather than wrapping it in
-a preprocessor conditional. (However, if a function or variable *always* goes
-unused, delete it.)
-
-Within code, where possible, use the IS_ENABLED macro to convert a Kconfig
-symbol into a C boolean expression, and use it in a normal C conditional:
-
-.. code-block:: c
-
- if (IS_ENABLED(CONFIG_SOMETHING)) {
- ...
- }
-
-The compiler will constant-fold the conditional away, and include or exclude
-the block of code just as with an #ifdef, so this will not add any runtime
-overhead. However, this approach still allows the C compiler to see the code
-inside the block, and check it for correctness (syntax, types, symbol
-references, etc). Thus, you still have to use an #ifdef if the code inside the
-block references symbols that will not exist if the condition is not met.
-
-At the end of any non-trivial #if or #ifdef block (more than a few lines),
-place a comment after the #endif on the same line, noting the conditional
-expression used. For instance:
-
-.. code-block:: c
-
- #ifdef CONFIG_SOMETHING
- ...
- #endif /* CONFIG_SOMETHING */
-
-
-Appendix I) References
-----------------------
-
-The C Programming Language, Second Edition
-by Brian W. Kernighan and Dennis M. Ritchie.
-Prentice Hall, Inc., 1988.
-ISBN 0-13-110362-8 (paperback), 0-13-110370-9 (hardback).
-
-The Practice of Programming
-by Brian W. Kernighan and Rob Pike.
-Addison-Wesley, Inc., 1999.
-ISBN 0-201-61586-X.
-
-GNU manuals - where in compliance with K&R and this text - for cpp, gcc,
-gcc internals and indent, all available from http://www.gnu.org/manual/
-
-WG14 is the international standardization working group for the programming
-language C, URL: http://www.open-std.org/JTC1/SC22/WG14/
-
-Kernel CodingStyle, by greg@kroah.com at OLS 2002:
-http://www.kroah.com/linux/talks/ols_2002_kernel_codingstyle_talk/html/
+This file has moved to process/coding-style.rst
diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile
index fdf8232d0eeb..caab9039362f 100644
--- a/Documentation/DocBook/Makefile
+++ b/Documentation/DocBook/Makefile
@@ -9,12 +9,10 @@
DOCBOOKS := z8530book.xml \
kernel-hacking.xml kernel-locking.xml deviceiobook.xml \
writing_usb_driver.xml networking.xml \
- kernel-api.xml filesystems.xml lsm.xml usb.xml kgdb.xml \
+ kernel-api.xml filesystems.xml lsm.xml kgdb.xml \
gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \
genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \
- debugobjects.xml sh.xml regulator.xml \
- alsa-driver-api.xml writing-an-alsa-driver.xml \
- tracepoint.xml w1.xml \
+ 80211.xml sh.xml regulator.xml w1.xml \
writing_musb_glue_layer.xml crypto-API.xml iio.xml
ifeq ($(DOCBOOKS),)
@@ -264,6 +262,7 @@ clean-files := $(DOCBOOKS) \
$(patsubst %.xml, %.aux.xml, $(DOCBOOKS)) \
$(patsubst %.xml, %.xml.db, $(DOCBOOKS)) \
$(patsubst %.xml, %.xml, $(DOCBOOKS)) \
+ $(patsubst %.xml, .%.xml.cmd, $(DOCBOOKS)) \
$(index)
clean-dirs := $(patsubst %.xml,%,$(DOCBOOKS)) man
diff --git a/Documentation/DocBook/alsa-driver-api.tmpl b/Documentation/DocBook/alsa-driver-api.tmpl
deleted file mode 100644
index 53f439dcc94b..000000000000
--- a/Documentation/DocBook/alsa-driver-api.tmpl
+++ /dev/null
@@ -1,142 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
- "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
-
-<!-- ****************************************************** -->
-<!-- Header -->
-<!-- ****************************************************** -->
-<book id="ALSA-Driver-API">
- <bookinfo>
- <title>The ALSA Driver API</title>
-
- <legalnotice>
- <para>
- This document is free; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
- </para>
-
- <para>
- This document is distributed in the hope that it will be useful,
- but <emphasis>WITHOUT ANY WARRANTY</emphasis>; without even the
- implied warranty of <emphasis>MERCHANTABILITY or FITNESS FOR A
- PARTICULAR PURPOSE</emphasis>. See the GNU General Public License
- for more details.
- </para>
-
- <para>
- You should have received a copy of the GNU General Public
- License along with this program; if not, write to the Free
- Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
- MA 02111-1307 USA
- </para>
- </legalnotice>
-
- </bookinfo>
-
-<toc></toc>
-
- <chapter><title>Management of Cards and Devices</title>
- <sect1><title>Card Management</title>
-!Esound/core/init.c
- </sect1>
- <sect1><title>Device Components</title>
-!Esound/core/device.c
- </sect1>
- <sect1><title>Module requests and Device File Entries</title>
-!Esound/core/sound.c
- </sect1>
- <sect1><title>Memory Management Helpers</title>
-!Esound/core/memory.c
-!Esound/core/memalloc.c
- </sect1>
- </chapter>
- <chapter><title>PCM API</title>
- <sect1><title>PCM Core</title>
-!Esound/core/pcm.c
-!Esound/core/pcm_lib.c
-!Esound/core/pcm_native.c
-!Iinclude/sound/pcm.h
- </sect1>
- <sect1><title>PCM Format Helpers</title>
-!Esound/core/pcm_misc.c
- </sect1>
- <sect1><title>PCM Memory Management</title>
-!Esound/core/pcm_memory.c
- </sect1>
- <sect1><title>PCM DMA Engine API</title>
-!Esound/core/pcm_dmaengine.c
-!Iinclude/sound/dmaengine_pcm.h
- </sect1>
- </chapter>
- <chapter><title>Control/Mixer API</title>
- <sect1><title>General Control Interface</title>
-!Esound/core/control.c
- </sect1>
- <sect1><title>AC97 Codec API</title>
-!Esound/pci/ac97/ac97_codec.c
-!Esound/pci/ac97/ac97_pcm.c
- </sect1>
- <sect1><title>Virtual Master Control API</title>
-!Esound/core/vmaster.c
-!Iinclude/sound/control.h
- </sect1>
- </chapter>
- <chapter><title>MIDI API</title>
- <sect1><title>Raw MIDI API</title>
-!Esound/core/rawmidi.c
- </sect1>
- <sect1><title>MPU401-UART API</title>
-!Esound/drivers/mpu401/mpu401_uart.c
- </sect1>
- </chapter>
- <chapter><title>Proc Info API</title>
- <sect1><title>Proc Info Interface</title>
-!Esound/core/info.c
- </sect1>
- </chapter>
- <chapter><title>Compress Offload</title>
- <sect1><title>Compress Offload API</title>
-!Esound/core/compress_offload.c
-!Iinclude/uapi/sound/compress_offload.h
-!Iinclude/uapi/sound/compress_params.h
-!Iinclude/sound/compress_driver.h
- </sect1>
- </chapter>
- <chapter><title>ASoC</title>
- <sect1><title>ASoC Core API</title>
-!Iinclude/sound/soc.h
-!Esound/soc/soc-core.c
-<!-- !Esound/soc/soc-cache.c no docbook comments here -->
-!Esound/soc/soc-devres.c
-!Esound/soc/soc-io.c
-!Esound/soc/soc-pcm.c
-!Esound/soc/soc-ops.c
-!Esound/soc/soc-compress.c
- </sect1>
- <sect1><title>ASoC DAPM API</title>
-!Esound/soc/soc-dapm.c
- </sect1>
- <sect1><title>ASoC DMA Engine API</title>
-!Esound/soc/soc-generic-dmaengine-pcm.c
- </sect1>
- </chapter>
- <chapter><title>Miscellaneous Functions</title>
- <sect1><title>Hardware-Dependent Devices API</title>
-!Esound/core/hwdep.c
- </sect1>
- <sect1><title>Jack Abstraction Layer API</title>
-!Iinclude/sound/jack.h
-!Esound/core/jack.c
-!Esound/soc/soc-jack.c
- </sect1>
- <sect1><title>ISA DMA Helpers</title>
-!Esound/core/isadma.c
- </sect1>
- <sect1><title>Other Helper Macros</title>
-!Iinclude/sound/core.h
- </sect1>
- </chapter>
-
-</book>
diff --git a/Documentation/DocBook/debugobjects.tmpl b/Documentation/DocBook/debugobjects.tmpl
deleted file mode 100644
index 7e4f34fde697..000000000000
--- a/Documentation/DocBook/debugobjects.tmpl
+++ /dev/null
@@ -1,443 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
- "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
-
-<book id="debug-objects-guide">
- <bookinfo>
- <title>Debug objects life time</title>
-
- <authorgroup>
- <author>
- <firstname>Thomas</firstname>
- <surname>Gleixner</surname>
- <affiliation>
- <address>
- <email>tglx@linutronix.de</email>
- </address>
- </affiliation>
- </author>
- </authorgroup>
-
- <copyright>
- <year>2008</year>
- <holder>Thomas Gleixner</holder>
- </copyright>
-
- <legalnotice>
- <para>
- This documentation is free software; you can redistribute
- it and/or modify it under the terms of the GNU General Public
- License version 2 as published by the Free Software Foundation.
- </para>
-
- <para>
- This program is distributed in the hope that it will be
- useful, but WITHOUT ANY WARRANTY; without even the implied
- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
- See the GNU General Public License for more details.
- </para>
-
- <para>
- You should have received a copy of the GNU General Public
- License along with this program; if not, write to the Free
- Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
- MA 02111-1307 USA
- </para>
-
- <para>
- For more details see the file COPYING in the source
- distribution of Linux.
- </para>
- </legalnotice>
- </bookinfo>
-
-<toc></toc>
-
- <chapter id="intro">
- <title>Introduction</title>
- <para>
- debugobjects is a generic infrastructure to track the life time
- of kernel objects and validate the operations on those.
- </para>
- <para>
- debugobjects is useful to check for the following error patterns:
- <itemizedlist>
- <listitem><para>Activation of uninitialized objects</para></listitem>
- <listitem><para>Initialization of active objects</para></listitem>
- <listitem><para>Usage of freed/destroyed objects</para></listitem>
- </itemizedlist>
- </para>
- <para>
- debugobjects is not changing the data structure of the real
- object so it can be compiled in with a minimal runtime impact
- and enabled on demand with a kernel command line option.
- </para>
- </chapter>
-
- <chapter id="howto">
- <title>Howto use debugobjects</title>
- <para>
- A kernel subsystem needs to provide a data structure which
- describes the object type and add calls into the debug code at
- appropriate places. The data structure to describe the object
- type needs at minimum the name of the object type. Optional
- functions can and should be provided to fixup detected problems
- so the kernel can continue to work and the debug information can
- be retrieved from a live system instead of hard core debugging
- with serial consoles and stack trace transcripts from the
- monitor.
- </para>
- <para>
- The debug calls provided by debugobjects are:
- <itemizedlist>
- <listitem><para>debug_object_init</para></listitem>
- <listitem><para>debug_object_init_on_stack</para></listitem>
- <listitem><para>debug_object_activate</para></listitem>
- <listitem><para>debug_object_deactivate</para></listitem>
- <listitem><para>debug_object_destroy</para></listitem>
- <listitem><para>debug_object_free</para></listitem>
- <listitem><para>debug_object_assert_init</para></listitem>
- </itemizedlist>
- Each of these functions takes the address of the real object and
- a pointer to the object type specific debug description
- structure.
- </para>
- <para>
- Each detected error is reported in the statistics and a limited
- number of errors are printk'ed including a full stack trace.
- </para>
- <para>
- The statistics are available via /sys/kernel/debug/debug_objects/stats.
- They provide information about the number of warnings and the
- number of successful fixups along with information about the
- usage of the internal tracking objects and the state of the
- internal tracking objects pool.
- </para>
- </chapter>
- <chapter id="debugfunctions">
- <title>Debug functions</title>
- <sect1 id="prototypes">
- <title>Debug object function reference</title>
-!Elib/debugobjects.c
- </sect1>
- <sect1 id="debug_object_init">
- <title>debug_object_init</title>
- <para>
- This function is called whenever the initialization function
- of a real object is called.
- </para>
- <para>
- When the real object is already tracked by debugobjects it is
- checked, whether the object can be initialized. Initializing
- is not allowed for active and destroyed objects. When
- debugobjects detects an error, then it calls the fixup_init
- function of the object type description structure if provided
- by the caller. The fixup function can correct the problem
- before the real initialization of the object happens. E.g. it
- can deactivate an active object in order to prevent damage to
- the subsystem.
- </para>
- <para>
- When the real object is not yet tracked by debugobjects,
- debugobjects allocates a tracker object for the real object
- and sets the tracker object state to ODEBUG_STATE_INIT. It
- verifies that the object is not on the callers stack. If it is
- on the callers stack then a limited number of warnings
- including a full stack trace is printk'ed. The calling code
- must use debug_object_init_on_stack() and remove the object
- before leaving the function which allocated it. See next
- section.
- </para>
- </sect1>
-
- <sect1 id="debug_object_init_on_stack">
- <title>debug_object_init_on_stack</title>
- <para>
- This function is called whenever the initialization function
- of a real object which resides on the stack is called.
- </para>
- <para>
- When the real object is already tracked by debugobjects it is
- checked, whether the object can be initialized. Initializing
- is not allowed for active and destroyed objects. When
- debugobjects detects an error, then it calls the fixup_init
- function of the object type description structure if provided
- by the caller. The fixup function can correct the problem
- before the real initialization of the object happens. E.g. it
- can deactivate an active object in order to prevent damage to
- the subsystem.
- </para>
- <para>
- When the real object is not yet tracked by debugobjects
- debugobjects allocates a tracker object for the real object
- and sets the tracker object state to ODEBUG_STATE_INIT. It
- verifies that the object is on the callers stack.
- </para>
- <para>
- An object which is on the stack must be removed from the
- tracker by calling debug_object_free() before the function
- which allocates the object returns. Otherwise we keep track of
- stale objects.
- </para>
- </sect1>
-
- <sect1 id="debug_object_activate">
- <title>debug_object_activate</title>
- <para>
- This function is called whenever the activation function of a
- real object is called.
- </para>
- <para>
- When the real object is already tracked by debugobjects it is
- checked, whether the object can be activated. Activating is
- not allowed for active and destroyed objects. When
- debugobjects detects an error, then it calls the
- fixup_activate function of the object type description
- structure if provided by the caller. The fixup function can
- correct the problem before the real activation of the object
- happens. E.g. it can deactivate an active object in order to
- prevent damage to the subsystem.
- </para>
- <para>
- When the real object is not yet tracked by debugobjects then
- the fixup_activate function is called if available. This is
- necessary to allow the legitimate activation of statically
- allocated and initialized objects. The fixup function checks
- whether the object is valid and calls the debug_objects_init()
- function to initialize the tracking of this object.
- </para>
- <para>
- When the activation is legitimate, then the state of the
- associated tracker object is set to ODEBUG_STATE_ACTIVE.
- </para>
- </sect1>
-
- <sect1 id="debug_object_deactivate">
- <title>debug_object_deactivate</title>
- <para>
- This function is called whenever the deactivation function of
- a real object is called.
- </para>
- <para>
- When the real object is tracked by debugobjects it is checked,
- whether the object can be deactivated. Deactivating is not
- allowed for untracked or destroyed objects.
- </para>
- <para>
- When the deactivation is legitimate, then the state of the
- associated tracker object is set to ODEBUG_STATE_INACTIVE.
- </para>
- </sect1>
-
- <sect1 id="debug_object_destroy">
- <title>debug_object_destroy</title>
- <para>
- This function is called to mark an object destroyed. This is
- useful to prevent the usage of invalid objects, which are
- still available in memory: either statically allocated objects
- or objects which are freed later.
- </para>
- <para>
- When the real object is tracked by debugobjects it is checked,
- whether the object can be destroyed. Destruction is not
- allowed for active and destroyed objects. When debugobjects
- detects an error, then it calls the fixup_destroy function of
- the object type description structure if provided by the
- caller. The fixup function can correct the problem before the
- real destruction of the object happens. E.g. it can deactivate
- an active object in order to prevent damage to the subsystem.
- </para>
- <para>
- When the destruction is legitimate, then the state of the
- associated tracker object is set to ODEBUG_STATE_DESTROYED.
- </para>
- </sect1>
-
- <sect1 id="debug_object_free">
- <title>debug_object_free</title>
- <para>
- This function is called before an object is freed.
- </para>
- <para>
- When the real object is tracked by debugobjects it is checked,
- whether the object can be freed. Free is not allowed for
- active objects. When debugobjects detects an error, then it
- calls the fixup_free function of the object type description
- structure if provided by the caller. The fixup function can
- correct the problem before the real free of the object
- happens. E.g. it can deactivate an active object in order to
- prevent damage to the subsystem.
- </para>
- <para>
- Note that debug_object_free removes the object from the
- tracker. Later usage of the object is detected by the other
- debug checks.
- </para>
- </sect1>
-
- <sect1 id="debug_object_assert_init">
- <title>debug_object_assert_init</title>
- <para>
- This function is called to assert that an object has been
- initialized.
- </para>
- <para>
- When the real object is not tracked by debugobjects, it calls
- fixup_assert_init of the object type description structure
- provided by the caller, with the hardcoded object state
- ODEBUG_NOT_AVAILABLE. The fixup function can correct the problem
- by calling debug_object_init and other specific initializing
- functions.
- </para>
- <para>
- When the real object is already tracked by debugobjects it is
- ignored.
- </para>
- </sect1>
- </chapter>
- <chapter id="fixupfunctions">
- <title>Fixup functions</title>
- <sect1 id="debug_obj_descr">
- <title>Debug object type description structure</title>
-!Iinclude/linux/debugobjects.h
- </sect1>
- <sect1 id="fixup_init">
- <title>fixup_init</title>
- <para>
- This function is called from the debug code whenever a problem
- in debug_object_init is detected. The function takes the
- address of the object and the state which is currently
- recorded in the tracker.
- </para>
- <para>
- Called from debug_object_init when the object state is:
- <itemizedlist>
- <listitem><para>ODEBUG_STATE_ACTIVE</para></listitem>
- </itemizedlist>
- </para>
- <para>
- The function returns true when the fixup was successful,
- otherwise false. The return value is used to update the
- statistics.
- </para>
- <para>
- Note, that the function needs to call the debug_object_init()
- function again, after the damage has been repaired in order to
- keep the state consistent.
- </para>
- </sect1>
-
- <sect1 id="fixup_activate">
- <title>fixup_activate</title>
- <para>
- This function is called from the debug code whenever a problem
- in debug_object_activate is detected.
- </para>
- <para>
- Called from debug_object_activate when the object state is:
- <itemizedlist>
- <listitem><para>ODEBUG_STATE_NOTAVAILABLE</para></listitem>
- <listitem><para>ODEBUG_STATE_ACTIVE</para></listitem>
- </itemizedlist>
- </para>
- <para>
- The function returns true when the fixup was successful,
- otherwise false. The return value is used to update the
- statistics.
- </para>
- <para>
- Note that the function needs to call the debug_object_activate()
- function again after the damage has been repaired in order to
- keep the state consistent.
- </para>
- <para>
- The activation of statically initialized objects is a special
- case. When debug_object_activate() has no tracked object for
- this object address then fixup_activate() is called with
- object state ODEBUG_STATE_NOTAVAILABLE. The fixup function
- needs to check whether this is a legitimate case of a
- statically initialized object or not. In case it is it calls
- debug_object_init() and debug_object_activate() to make the
- object known to the tracker and marked active. In this case
- the function should return false because this is not a real
- fixup.
- </para>
- </sect1>
-
- <sect1 id="fixup_destroy">
- <title>fixup_destroy</title>
- <para>
- This function is called from the debug code whenever a problem
- in debug_object_destroy is detected.
- </para>
- <para>
- Called from debug_object_destroy when the object state is:
- <itemizedlist>
- <listitem><para>ODEBUG_STATE_ACTIVE</para></listitem>
- </itemizedlist>
- </para>
- <para>
- The function returns true when the fixup was successful,
- otherwise false. The return value is used to update the
- statistics.
- </para>
- </sect1>
- <sect1 id="fixup_free">
- <title>fixup_free</title>
- <para>
- This function is called from the debug code whenever a problem
- in debug_object_free is detected. Further it can be called
- from the debug checks in kfree/vfree, when an active object is
- detected from the debug_check_no_obj_freed() sanity checks.
- </para>
- <para>
- Called from debug_object_free() or debug_check_no_obj_freed()
- when the object state is:
- <itemizedlist>
- <listitem><para>ODEBUG_STATE_ACTIVE</para></listitem>
- </itemizedlist>
- </para>
- <para>
- The function returns true when the fixup was successful,
- otherwise false. The return value is used to update the
- statistics.
- </para>
- </sect1>
- <sect1 id="fixup_assert_init">
- <title>fixup_assert_init</title>
- <para>
- This function is called from the debug code whenever a problem
- in debug_object_assert_init is detected.
- </para>
- <para>
- Called from debug_object_assert_init() with a hardcoded state
- ODEBUG_STATE_NOTAVAILABLE when the object is not found in the
- debug bucket.
- </para>
- <para>
- The function returns true when the fixup was successful,
- otherwise false. The return value is used to update the
- statistics.
- </para>
- <para>
- Note, this function should make sure debug_object_init() is
- called before returning.
- </para>
- <para>
- The handling of statically initialized objects is a special
- case. The fixup function should check if this is a legitimate
- case of a statically initialized object or not. In this case only
- debug_object_init() should be called to make the object known to
- the tracker. Then the function should return false because this
- is not
- a real fixup.
- </para>
- </sect1>
- </chapter>
- <chapter id="bugs">
- <title>Known Bugs And Assumptions</title>
- <para>
- None (knock on wood).
- </para>
- </chapter>
-</book>
diff --git a/Documentation/DocBook/kernel-hacking.tmpl b/Documentation/DocBook/kernel-hacking.tmpl
index 2a272275c81b..da5c087462b1 100644
--- a/Documentation/DocBook/kernel-hacking.tmpl
+++ b/Documentation/DocBook/kernel-hacking.tmpl
@@ -1208,8 +1208,8 @@ static struct block_device_operations opt_fops = {
<listitem>
<para>
- Finally, don't forget to read <filename>Documentation/SubmittingPatches</filename>
- and possibly <filename>Documentation/SubmittingDrivers</filename>.
+ Finally, don't forget to read <filename>Documentation/process/submitting-patches.rst</filename>
+ and possibly <filename>Documentation/process/submitting-drivers.rst</filename>.
</para>
</listitem>
</itemizedlist>
diff --git a/Documentation/DocBook/tracepoint.tmpl b/Documentation/DocBook/tracepoint.tmpl
deleted file mode 100644
index b57a9ede3224..000000000000
--- a/Documentation/DocBook/tracepoint.tmpl
+++ /dev/null
@@ -1,112 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
- "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
-
-<book id="Tracepoints">
- <bookinfo>
- <title>The Linux Kernel Tracepoint API</title>
-
- <authorgroup>
- <author>
- <firstname>Jason</firstname>
- <surname>Baron</surname>
- <affiliation>
- <address>
- <email>jbaron@redhat.com</email>
- </address>
- </affiliation>
- </author>
- <author>
- <firstname>William</firstname>
- <surname>Cohen</surname>
- <affiliation>
- <address>
- <email>wcohen@redhat.com</email>
- </address>
- </affiliation>
- </author>
- </authorgroup>
-
- <legalnotice>
- <para>
- This documentation is free software; you can redistribute
- it and/or modify it under the terms of the GNU General Public
- License as published by the Free Software Foundation; either
- version 2 of the License, or (at your option) any later
- version.
- </para>
-
- <para>
- This program is distributed in the hope that it will be
- useful, but WITHOUT ANY WARRANTY; without even the implied
- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
- See the GNU General Public License for more details.
- </para>
-
- <para>
- You should have received a copy of the GNU General Public
- License along with this program; if not, write to the Free
- Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
- MA 02111-1307 USA
- </para>
-
- <para>
- For more details see the file COPYING in the source
- distribution of Linux.
- </para>
- </legalnotice>
- </bookinfo>
-
- <toc></toc>
- <chapter id="intro">
- <title>Introduction</title>
- <para>
- Tracepoints are static probe points that are located in strategic points
- throughout the kernel. 'Probes' register/unregister with tracepoints
- via a callback mechanism. The 'probes' are strictly typed functions that
- are passed a unique set of parameters defined by each tracepoint.
- </para>
-
- <para>
- From this simple callback mechanism, 'probes' can be used to profile, debug,
- and understand kernel behavior. There are a number of tools that provide a
- framework for using 'probes'. These tools include Systemtap, ftrace, and
- LTTng.
- </para>
-
- <para>
- Tracepoints are defined in a number of header files via various macros. Thus,
- the purpose of this document is to provide a clear accounting of the available
- tracepoints. The intention is to understand not only what tracepoints are
- available but also to understand where future tracepoints might be added.
- </para>
-
- <para>
- The API presented has functions of the form:
- <function>trace_tracepointname(function parameters)</function>. These are the
- tracepoints callbacks that are found throughout the code. Registering and
- unregistering probes with these callback sites is covered in the
- <filename>Documentation/trace/*</filename> directory.
- </para>
- </chapter>
-
- <chapter id="irq">
- <title>IRQ</title>
-!Iinclude/trace/events/irq.h
- </chapter>
-
- <chapter id="signal">
- <title>SIGNAL</title>
-!Iinclude/trace/events/signal.h
- </chapter>
-
- <chapter id="block">
- <title>Block IO</title>
-!Iinclude/trace/events/block.h
- </chapter>
-
- <chapter id="workqueue">
- <title>Workqueue</title>
-!Iinclude/trace/events/workqueue.h
- </chapter>
-</book>
diff --git a/Documentation/DocBook/uio-howto.tmpl b/Documentation/DocBook/uio-howto.tmpl
index cd0e452dfed5..5210f8a577c6 100644
--- a/Documentation/DocBook/uio-howto.tmpl
+++ b/Documentation/DocBook/uio-howto.tmpl
@@ -46,6 +46,13 @@ GPL version 2.
<revhistory>
<revision>
+ <revnumber>0.10</revnumber>
+ <date>2016-10-17</date>
+ <authorinitials>sch</authorinitials>
+ <revremark>Added generic hyperv driver
+ </revremark>
+ </revision>
+ <revision>
<revnumber>0.9</revnumber>
<date>2009-07-16</date>
<authorinitials>mst</authorinitials>
@@ -1033,6 +1040,61 @@ int main()
</chapter>
+<chapter id="uio_hv_generic" xreflabel="Using Generic driver for Hyper-V VMBUS">
+<?dbhtml filename="uio_hv_generic.html"?>
+<title>Generic Hyper-V UIO driver</title>
+ <para>
+ The generic driver is a kernel module named uio_hv_generic.
+ It supports devices on the Hyper-V VMBus similar to uio_pci_generic
+ on PCI bus.
+ </para>
+
+<sect1 id="uio_hv_generic_binding">
+<title>Making the driver recognize the device</title>
+ <para>
+Since the driver does not declare any device GUID's, it will not get loaded
+automatically and will not automatically bind to any devices, you must load it
+and allocate id to the driver yourself. For example, to use the network device
+GUID:
+ <programlisting>
+ modprobe uio_hv_generic
+ echo &quot;f8615163-df3e-46c5-913f-f2d2f965ed0e&quot; &gt; /sys/bus/vmbus/drivers/uio_hv_generic/new_id
+ </programlisting>
+ </para>
+ <para>
+If there already is a hardware specific kernel driver for the device, the
+generic driver still won't bind to it, in this case if you want to use the
+generic driver (why would you?) you'll have to manually unbind the hardware
+specific driver and bind the generic driver, like this:
+ <programlisting>
+ echo -n vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3 &gt; /sys/bus/vmbus/drivers/hv_netvsc/unbind
+ echo -n vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3 &gt; /sys/bus/vmbus/drivers/uio_hv_generic/bind
+ </programlisting>
+ </para>
+ <para>
+You can verify that the device has been bound to the driver
+by looking for it in sysfs, for example like the following:
+ <programlisting>
+ ls -l /sys/bus/vmbus/devices/vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3/driver
+ </programlisting>
+Which if successful should print
+ <programlisting>
+ .../vmbus-ed963694-e847-4b2a-85af-bc9cfc11d6f3/driver -&gt; ../../../bus/vmbus/drivers/uio_hv_generic
+ </programlisting>
+ </para>
+</sect1>
+
+<sect1 id="uio_hv_generic_internals">
+<title>Things to know about uio_hv_generic</title>
+ <para>
+On each interrupt, uio_hv_generic sets the Interrupt Disable bit.
+This prevents the device from generating further interrupts
+until the bit is cleared. The userspace driver should clear this
+bit before blocking and waiting for more interrupts.
+ </para>
+</sect1>
+</chapter>
+
<appendix id="app1">
<title>Further information</title>
<itemizedlist>
diff --git a/Documentation/DocBook/usb.tmpl b/Documentation/DocBook/usb.tmpl
deleted file mode 100644
index bc776be0f19c..000000000000
--- a/Documentation/DocBook/usb.tmpl
+++ /dev/null
@@ -1,992 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
- "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
-
-<book id="Linux-USB-API">
- <bookinfo>
- <title>The Linux-USB Host Side API</title>
-
- <legalnotice>
- <para>
- This documentation is free software; you can redistribute
- it and/or modify it under the terms of the GNU General Public
- License as published by the Free Software Foundation; either
- version 2 of the License, or (at your option) any later
- version.
- </para>
-
- <para>
- This program is distributed in the hope that it will be
- useful, but WITHOUT ANY WARRANTY; without even the implied
- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
- See the GNU General Public License for more details.
- </para>
-
- <para>
- You should have received a copy of the GNU General Public
- License along with this program; if not, write to the Free
- Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
- MA 02111-1307 USA
- </para>
-
- <para>
- For more details see the file COPYING in the source
- distribution of Linux.
- </para>
- </legalnotice>
- </bookinfo>
-
-<toc></toc>
-
-<chapter id="intro">
- <title>Introduction to USB on Linux</title>
-
- <para>A Universal Serial Bus (USB) is used to connect a host,
- such as a PC or workstation, to a number of peripheral
- devices. USB uses a tree structure, with the host as the
- root (the system's master), hubs as interior nodes, and
- peripherals as leaves (and slaves).
- Modern PCs support several such trees of USB devices, usually
- one USB 2.0 tree (480 Mbit/sec each) with
- a few USB 1.1 trees (12 Mbit/sec each) that are used when you
- connect a USB 1.1 device directly to the machine's "root hub".
- </para>
-
- <para>That master/slave asymmetry was designed-in for a number of
- reasons, one being ease of use. It is not physically possible to
- assemble (legal) USB cables incorrectly: all upstream "to the host"
- connectors are the rectangular type (matching the sockets on
- root hubs), and all downstream connectors are the squarish type
- (or they are built into the peripheral).
- Also, the host software doesn't need to deal with distributed
- auto-configuration since the pre-designated master node manages all that.
- And finally, at the electrical level, bus protocol overhead is reduced by
- eliminating arbitration and moving scheduling into the host software.
- </para>
-
- <para>USB 1.0 was announced in January 1996 and was revised
- as USB 1.1 (with improvements in hub specification and
- support for interrupt-out transfers) in September 1998.
- USB 2.0 was released in April 2000, adding high-speed
- transfers and transaction-translating hubs (used for USB 1.1
- and 1.0 backward compatibility).
- </para>
-
- <para>Kernel developers added USB support to Linux early in the 2.2 kernel
- series, shortly before 2.3 development forked. Updates from 2.3 were
- regularly folded back into 2.2 releases, which improved reliability and
- brought <filename>/sbin/hotplug</filename> support as well more drivers.
- Such improvements were continued in the 2.5 kernel series, where they added
- USB 2.0 support, improved performance, and made the host controller drivers
- (HCDs) more consistent. They also simplified the API (to make bugs less
- likely) and added internal "kerneldoc" documentation.
- </para>
-
- <para>Linux can run inside USB devices as well as on
- the hosts that control the devices.
- But USB device drivers running inside those peripherals
- don't do the same things as the ones running inside hosts,
- so they've been given a different name:
- <emphasis>gadget drivers</emphasis>.
- This document does not cover gadget drivers.
- </para>
-
- </chapter>
-
-<chapter id="host">
- <title>USB Host-Side API Model</title>
-
- <para>Host-side drivers for USB devices talk to the "usbcore" APIs.
- There are two. One is intended for
- <emphasis>general-purpose</emphasis> drivers (exposed through
- driver frameworks), and the other is for drivers that are
- <emphasis>part of the core</emphasis>.
- Such core drivers include the <emphasis>hub</emphasis> driver
- (which manages trees of USB devices) and several different kinds
- of <emphasis>host controller drivers</emphasis>,
- which control individual busses.
- </para>
-
- <para>The device model seen by USB drivers is relatively complex.
- </para>
-
- <itemizedlist>
-
- <listitem><para>USB supports four kinds of data transfers
- (control, bulk, interrupt, and isochronous). Two of them (control
- and bulk) use bandwidth as it's available,
- while the other two (interrupt and isochronous)
- are scheduled to provide guaranteed bandwidth.
- </para></listitem>
-
- <listitem><para>The device description model includes one or more
- "configurations" per device, only one of which is active at a time.
- Devices that are capable of high-speed operation must also support
- full-speed configurations, along with a way to ask about the
- "other speed" configurations which might be used.
- </para></listitem>
-
- <listitem><para>Configurations have one or more "interfaces", each
- of which may have "alternate settings". Interfaces may be
- standardized by USB "Class" specifications, or may be specific to
- a vendor or device.</para>
-
- <para>USB device drivers actually bind to interfaces, not devices.
- Think of them as "interface drivers", though you
- may not see many devices where the distinction is important.
- <emphasis>Most USB devices are simple, with only one configuration,
- one interface, and one alternate setting.</emphasis>
- </para></listitem>
-
- <listitem><para>Interfaces have one or more "endpoints", each of
- which supports one type and direction of data transfer such as
- "bulk out" or "interrupt in". The entire configuration may have
- up to sixteen endpoints in each direction, allocated as needed
- among all the interfaces.
- </para></listitem>
-
- <listitem><para>Data transfer on USB is packetized; each endpoint
- has a maximum packet size.
- Drivers must often be aware of conventions such as flagging the end
- of bulk transfers using "short" (including zero length) packets.
- </para></listitem>
-
- <listitem><para>The Linux USB API supports synchronous calls for
- control and bulk messages.
- It also supports asynchronous calls for all kinds of data transfer,
- using request structures called "URBs" (USB Request Blocks).
- </para></listitem>
-
- </itemizedlist>
-
- <para>Accordingly, the USB Core API exposed to device drivers
- covers quite a lot of territory. You'll probably need to consult
- the USB 2.0 specification, available online from www.usb.org at
- no cost, as well as class or device specifications.
- </para>
-
- <para>The only host-side drivers that actually touch hardware
- (reading/writing registers, handling IRQs, and so on) are the HCDs.
- In theory, all HCDs provide the same functionality through the same
- API. In practice, that's becoming more true on the 2.5 kernels,
- but there are still differences that crop up especially with
- fault handling. Different controllers don't necessarily report
- the same aspects of failures, and recovery from faults (including
- software-induced ones like unlinking an URB) isn't yet fully
- consistent.
- Device driver authors should make a point of doing disconnect
- testing (while the device is active) with each different host
- controller driver, to make sure drivers don't have bugs of
- their own as well as to make sure they aren't relying on some
- HCD-specific behavior.
- (You will need external USB 1.1 and/or
- USB 2.0 hubs to perform all those tests.)
- </para>
-
- </chapter>
-
-<chapter id="types"><title>USB-Standard Types</title>
-
- <para>In <filename>&lt;linux/usb/ch9.h&gt;</filename> you will find
- the USB data types defined in chapter 9 of the USB specification.
- These data types are used throughout USB, and in APIs including
- this host side API, gadget APIs, and usbfs.
- </para>
-
-!Iinclude/linux/usb/ch9.h
-
- </chapter>
-
-<chapter id="hostside"><title>Host-Side Data Types and Macros</title>
-
- <para>The host side API exposes several layers to drivers, some of
- which are more necessary than others.
- These support lifecycle models for host side drivers
- and devices, and support passing buffers through usbcore to
- some HCD that performs the I/O for the device driver.
- </para>
-
-
-!Iinclude/linux/usb.h
-
- </chapter>
-
- <chapter id="usbcore"><title>USB Core APIs</title>
-
- <para>There are two basic I/O models in the USB API.
- The most elemental one is asynchronous: drivers submit requests
- in the form of an URB, and the URB's completion callback
- handle the next step.
- All USB transfer types support that model, although there
- are special cases for control URBs (which always have setup
- and status stages, but may not have a data stage) and
- isochronous URBs (which allow large packets and include
- per-packet fault reports).
- Built on top of that is synchronous API support, where a
- driver calls a routine that allocates one or more URBs,
- submits them, and waits until they complete.
- There are synchronous wrappers for single-buffer control
- and bulk transfers (which are awkward to use in some
- driver disconnect scenarios), and for scatterlist based
- streaming i/o (bulk or interrupt).
- </para>
-
- <para>USB drivers need to provide buffers that can be
- used for DMA, although they don't necessarily need to
- provide the DMA mapping themselves.
- There are APIs to use used when allocating DMA buffers,
- which can prevent use of bounce buffers on some systems.
- In some cases, drivers may be able to rely on 64bit DMA
- to eliminate another kind of bounce buffer.
- </para>
-
-!Edrivers/usb/core/urb.c
-!Edrivers/usb/core/message.c
-!Edrivers/usb/core/file.c
-!Edrivers/usb/core/driver.c
-!Edrivers/usb/core/usb.c
-!Edrivers/usb/core/hub.c
- </chapter>
-
- <chapter id="hcd"><title>Host Controller APIs</title>
-
- <para>These APIs are only for use by host controller drivers,
- most of which implement standard register interfaces such as
- EHCI, OHCI, or UHCI.
- UHCI was one of the first interfaces, designed by Intel and
- also used by VIA; it doesn't do much in hardware.
- OHCI was designed later, to have the hardware do more work
- (bigger transfers, tracking protocol state, and so on).
- EHCI was designed with USB 2.0; its design has features that
- resemble OHCI (hardware does much more work) as well as
- UHCI (some parts of ISO support, TD list processing).
- </para>
-
- <para>There are host controllers other than the "big three",
- although most PCI based controllers (and a few non-PCI based
- ones) use one of those interfaces.
- Not all host controllers use DMA; some use PIO, and there
- is also a simulator.
- </para>
-
- <para>The same basic APIs are available to drivers for all
- those controllers.
- For historical reasons they are in two layers:
- <structname>struct usb_bus</structname> is a rather thin
- layer that became available in the 2.2 kernels, while
- <structname>struct usb_hcd</structname> is a more featureful
- layer (available in later 2.4 kernels and in 2.5) that
- lets HCDs share common code, to shrink driver size
- and significantly reduce hcd-specific behaviors.
- </para>
-
-!Edrivers/usb/core/hcd.c
-!Edrivers/usb/core/hcd-pci.c
-!Idrivers/usb/core/buffer.c
- </chapter>
-
- <chapter id="usbfs">
- <title>The USB Filesystem (usbfs)</title>
-
- <para>This chapter presents the Linux <emphasis>usbfs</emphasis>.
- You may prefer to avoid writing new kernel code for your
- USB driver; that's the problem that usbfs set out to solve.
- User mode device drivers are usually packaged as applications
- or libraries, and may use usbfs through some programming library
- that wraps it. Such libraries include
- <ulink url="http://libusb.sourceforge.net">libusb</ulink>
- for C/C++, and
- <ulink url="http://jUSB.sourceforge.net">jUSB</ulink> for Java.
- </para>
-
- <note><title>Unfinished</title>
- <para>This particular documentation is incomplete,
- especially with respect to the asynchronous mode.
- As of kernel 2.5.66 the code and this (new) documentation
- need to be cross-reviewed.
- </para>
- </note>
-
- <para>Configure usbfs into Linux kernels by enabling the
- <emphasis>USB filesystem</emphasis> option (CONFIG_USB_DEVICEFS),
- and you get basic support for user mode USB device drivers.
- Until relatively recently it was often (confusingly) called
- <emphasis>usbdevfs</emphasis> although it wasn't solving what
- <emphasis>devfs</emphasis> was.
- Every USB device will appear in usbfs, regardless of whether or
- not it has a kernel driver.
- </para>
-
- <sect1 id="usbfs-files">
- <title>What files are in "usbfs"?</title>
-
- <para>Conventionally mounted at
- <filename>/proc/bus/usb</filename>, usbfs
- features include:
- <itemizedlist>
- <listitem><para><filename>/proc/bus/usb/devices</filename>
- ... a text file
- showing each of the USB devices on known to the kernel,
- and their configuration descriptors.
- You can also poll() this to learn about new devices.
- </para></listitem>
- <listitem><para><filename>/proc/bus/usb/BBB/DDD</filename>
- ... magic files
- exposing the each device's configuration descriptors, and
- supporting a series of ioctls for making device requests,
- including I/O to devices. (Purely for access by programs.)
- </para></listitem>
- </itemizedlist>
- </para>
-
- <para> Each bus is given a number (BBB) based on when it was
- enumerated; within each bus, each device is given a similar
- number (DDD).
- Those BBB/DDD paths are not "stable" identifiers;
- expect them to change even if you always leave the devices
- plugged in to the same hub port.
- <emphasis>Don't even think of saving these in application
- configuration files.</emphasis>
- Stable identifiers are available, for user mode applications
- that want to use them. HID and networking devices expose
- these stable IDs, so that for example you can be sure that
- you told the right UPS to power down its second server.
- "usbfs" doesn't (yet) expose those IDs.
- </para>
-
- </sect1>
-
- <sect1 id="usbfs-fstab">
- <title>Mounting and Access Control</title>
-
- <para>There are a number of mount options for usbfs, which will
- be of most interest to you if you need to override the default
- access control policy.
- That policy is that only root may read or write device files
- (<filename>/proc/bus/BBB/DDD</filename>) although anyone may read
- the <filename>devices</filename>
- or <filename>drivers</filename> files.
- I/O requests to the device also need the CAP_SYS_RAWIO capability,
- </para>
-
- <para>The significance of that is that by default, all user mode
- device drivers need super-user privileges.
- You can change modes or ownership in a driver setup
- when the device hotplugs, or maye just start the
- driver right then, as a privileged server (or some activity
- within one).
- That's the most secure approach for multi-user systems,
- but for single user systems ("trusted" by that user)
- it's more convenient just to grant everyone all access
- (using the <emphasis>devmode=0666</emphasis> option)
- so the driver can start whenever it's needed.
- </para>
-
- <para>The mount options for usbfs, usable in /etc/fstab or
- in command line invocations of <emphasis>mount</emphasis>, are:
-
- <variablelist>
- <varlistentry>
- <term><emphasis>busgid</emphasis>=NNNNN</term>
- <listitem><para>Controls the GID used for the
- /proc/bus/usb/BBB
- directories. (Default: 0)</para></listitem></varlistentry>
- <varlistentry><term><emphasis>busmode</emphasis>=MMM</term>
- <listitem><para>Controls the file mode used for the
- /proc/bus/usb/BBB
- directories. (Default: 0555)
- </para></listitem></varlistentry>
- <varlistentry><term><emphasis>busuid</emphasis>=NNNNN</term>
- <listitem><para>Controls the UID used for the
- /proc/bus/usb/BBB
- directories. (Default: 0)</para></listitem></varlistentry>
-
- <varlistentry><term><emphasis>devgid</emphasis>=NNNNN</term>
- <listitem><para>Controls the GID used for the
- /proc/bus/usb/BBB/DDD
- files. (Default: 0)</para></listitem></varlistentry>
- <varlistentry><term><emphasis>devmode</emphasis>=MMM</term>
- <listitem><para>Controls the file mode used for the
- /proc/bus/usb/BBB/DDD
- files. (Default: 0644)</para></listitem></varlistentry>
- <varlistentry><term><emphasis>devuid</emphasis>=NNNNN</term>
- <listitem><para>Controls the UID used for the
- /proc/bus/usb/BBB/DDD
- files. (Default: 0)</para></listitem></varlistentry>
-
- <varlistentry><term><emphasis>listgid</emphasis>=NNNNN</term>
- <listitem><para>Controls the GID used for the
- /proc/bus/usb/devices and drivers files.
- (Default: 0)</para></listitem></varlistentry>
- <varlistentry><term><emphasis>listmode</emphasis>=MMM</term>
- <listitem><para>Controls the file mode used for the
- /proc/bus/usb/devices and drivers files.
- (Default: 0444)</para></listitem></varlistentry>
- <varlistentry><term><emphasis>listuid</emphasis>=NNNNN</term>
- <listitem><para>Controls the UID used for the
- /proc/bus/usb/devices and drivers files.
- (Default: 0)</para></listitem></varlistentry>
- </variablelist>
-
- </para>
-
- <para>Note that many Linux distributions hard-wire the mount options
- for usbfs in their init scripts, such as
- <filename>/etc/rc.d/rc.sysinit</filename>,
- rather than making it easy to set this per-system
- policy in <filename>/etc/fstab</filename>.
- </para>
-
- </sect1>
-
- <sect1 id="usbfs-devices">
- <title>/proc/bus/usb/devices</title>
-
- <para>This file is handy for status viewing tools in user
- mode, which can scan the text format and ignore most of it.
- More detailed device status (including class and vendor
- status) is available from device-specific files.
- For information about the current format of this file,
- see the
- <filename>Documentation/usb/proc_usb_info.txt</filename>
- file in your Linux kernel sources.
- </para>
-
- <para>This file, in combination with the poll() system call, can
- also be used to detect when devices are added or removed:
-<programlisting>int fd;
-struct pollfd pfd;
-
-fd = open("/proc/bus/usb/devices", O_RDONLY);
-pfd = { fd, POLLIN, 0 };
-for (;;) {
- /* The first time through, this call will return immediately. */
- poll(&amp;pfd, 1, -1);
-
- /* To see what's changed, compare the file's previous and current
- contents or scan the filesystem. (Scanning is more precise.) */
-}</programlisting>
- Note that this behavior is intended to be used for informational
- and debug purposes. It would be more appropriate to use programs
- such as udev or HAL to initialize a device or start a user-mode
- helper program, for instance.
- </para>
- </sect1>
-
- <sect1 id="usbfs-bbbddd">
- <title>/proc/bus/usb/BBB/DDD</title>
-
- <para>Use these files in one of these basic ways:
- </para>
-
- <para><emphasis>They can be read,</emphasis>
- producing first the device descriptor
- (18 bytes) and then the descriptors for the current configuration.
- See the USB 2.0 spec for details about those binary data formats.
- You'll need to convert most multibyte values from little endian
- format to your native host byte order, although a few of the
- fields in the device descriptor (both of the BCD-encoded fields,
- and the vendor and product IDs) will be byteswapped for you.
- Note that configuration descriptors include descriptors for
- interfaces, altsettings, endpoints, and maybe additional
- class descriptors.
- </para>
-
- <para><emphasis>Perform USB operations</emphasis> using
- <emphasis>ioctl()</emphasis> requests to make endpoint I/O
- requests (synchronously or asynchronously) or manage
- the device.
- These requests need the CAP_SYS_RAWIO capability,
- as well as filesystem access permissions.
- Only one ioctl request can be made on one of these
- device files at a time.
- This means that if you are synchronously reading an endpoint
- from one thread, you won't be able to write to a different
- endpoint from another thread until the read completes.
- This works for <emphasis>half duplex</emphasis> protocols,
- but otherwise you'd use asynchronous i/o requests.
- </para>
-
- </sect1>
-
-
- <sect1 id="usbfs-lifecycle">
- <title>Life Cycle of User Mode Drivers</title>
-
- <para>Such a driver first needs to find a device file
- for a device it knows how to handle.
- Maybe it was told about it because a
- <filename>/sbin/hotplug</filename> event handling agent
- chose that driver to handle the new device.
- Or maybe it's an application that scans all the
- /proc/bus/usb device files, and ignores most devices.
- In either case, it should <function>read()</function> all
- the descriptors from the device file,
- and check them against what it knows how to handle.
- It might just reject everything except a particular
- vendor and product ID, or need a more complex policy.
- </para>
-
- <para>Never assume there will only be one such device
- on the system at a time!
- If your code can't handle more than one device at
- a time, at least detect when there's more than one, and
- have your users choose which device to use.
- </para>
-
- <para>Once your user mode driver knows what device to use,
- it interacts with it in either of two styles.
- The simple style is to make only control requests; some
- devices don't need more complex interactions than those.
- (An example might be software using vendor-specific control
- requests for some initialization or configuration tasks,
- with a kernel driver for the rest.)
- </para>
-
- <para>More likely, you need a more complex style driver:
- one using non-control endpoints, reading or writing data
- and claiming exclusive use of an interface.
- <emphasis>Bulk</emphasis> transfers are easiest to use,
- but only their sibling <emphasis>interrupt</emphasis> transfers
- work with low speed devices.
- Both interrupt and <emphasis>isochronous</emphasis> transfers
- offer service guarantees because their bandwidth is reserved.
- Such "periodic" transfers are awkward to use through usbfs,
- unless you're using the asynchronous calls. However, interrupt
- transfers can also be used in a synchronous "one shot" style.
- </para>
-
- <para>Your user-mode driver should never need to worry
- about cleaning up request state when the device is
- disconnected, although it should close its open file
- descriptors as soon as it starts seeing the ENODEV
- errors.
- </para>
-
- </sect1>
-
- <sect1 id="usbfs-ioctl"><title>The ioctl() Requests</title>
-
- <para>To use these ioctls, you need to include the following
- headers in your userspace program:
-<programlisting>#include &lt;linux/usb.h&gt;
-#include &lt;linux/usbdevice_fs.h&gt;
-#include &lt;asm/byteorder.h&gt;</programlisting>
- The standard USB device model requests, from "Chapter 9" of
- the USB 2.0 specification, are automatically included from
- the <filename>&lt;linux/usb/ch9.h&gt;</filename> header.
- </para>
-
- <para>Unless noted otherwise, the ioctl requests
- described here will
- update the modification time on the usbfs file to which
- they are applied (unless they fail).
- A return of zero indicates success; otherwise, a
- standard USB error code is returned. (These are
- documented in
- <filename>Documentation/usb/error-codes.txt</filename>
- in your kernel sources.)
- </para>
-
- <para>Each of these files multiplexes access to several
- I/O streams, one per endpoint.
- Each device has one control endpoint (endpoint zero)
- which supports a limited RPC style RPC access.
- Devices are configured
- by hub_wq (in the kernel) setting a device-wide
- <emphasis>configuration</emphasis> that affects things
- like power consumption and basic functionality.
- The endpoints are part of USB <emphasis>interfaces</emphasis>,
- which may have <emphasis>altsettings</emphasis>
- affecting things like which endpoints are available.
- Many devices only have a single configuration and interface,
- so drivers for them will ignore configurations and altsettings.
- </para>
-
-
- <sect2 id="usbfs-mgmt">
- <title>Management/Status Requests</title>
-
- <para>A number of usbfs requests don't deal very directly
- with device I/O.
- They mostly relate to device management and status.
- These are all synchronous requests.
- </para>
-
- <variablelist>
-
- <varlistentry><term>USBDEVFS_CLAIMINTERFACE</term>
- <listitem><para>This is used to force usbfs to
- claim a specific interface,
- which has not previously been claimed by usbfs or any other
- kernel driver.
- The ioctl parameter is an integer holding the number of
- the interface (bInterfaceNumber from descriptor).
- </para><para>
- Note that if your driver doesn't claim an interface
- before trying to use one of its endpoints, and no
- other driver has bound to it, then the interface is
- automatically claimed by usbfs.
- </para><para>
- This claim will be released by a RELEASEINTERFACE ioctl,
- or by closing the file descriptor.
- File modification time is not updated by this request.
- </para></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_CONNECTINFO</term>
- <listitem><para>Says whether the device is lowspeed.
- The ioctl parameter points to a structure like this:
-<programlisting>struct usbdevfs_connectinfo {
- unsigned int devnum;
- unsigned char slow;
-}; </programlisting>
- File modification time is not updated by this request.
- </para><para>
- <emphasis>You can't tell whether a "not slow"
- device is connected at high speed (480 MBit/sec)
- or just full speed (12 MBit/sec).</emphasis>
- You should know the devnum value already,
- it's the DDD value of the device file name.
- </para></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_GETDRIVER</term>
- <listitem><para>Returns the name of the kernel driver
- bound to a given interface (a string). Parameter
- is a pointer to this structure, which is modified:
-<programlisting>struct usbdevfs_getdriver {
- unsigned int interface;
- char driver[USBDEVFS_MAXDRIVERNAME + 1];
-};</programlisting>
- File modification time is not updated by this request.
- </para></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_IOCTL</term>
- <listitem><para>Passes a request from userspace through
- to a kernel driver that has an ioctl entry in the
- <emphasis>struct usb_driver</emphasis> it registered.
-<programlisting>struct usbdevfs_ioctl {
- int ifno;
- int ioctl_code;
- void *data;
-};
-
-/* user mode call looks like this.
- * 'request' becomes the driver->ioctl() 'code' parameter.
- * the size of 'param' is encoded in 'request', and that data
- * is copied to or from the driver->ioctl() 'buf' parameter.
- */
-static int
-usbdev_ioctl (int fd, int ifno, unsigned request, void *param)
-{
- struct usbdevfs_ioctl wrapper;
-
- wrapper.ifno = ifno;
- wrapper.ioctl_code = request;
- wrapper.data = param;
-
- return ioctl (fd, USBDEVFS_IOCTL, &amp;wrapper);
-} </programlisting>
- File modification time is not updated by this request.
- </para><para>
- This request lets kernel drivers talk to user mode code
- through filesystem operations even when they don't create
- a character or block special device.
- It's also been used to do things like ask devices what
- device special file should be used.
- Two pre-defined ioctls are used
- to disconnect and reconnect kernel drivers, so
- that user mode code can completely manage binding
- and configuration of devices.
- </para></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_RELEASEINTERFACE</term>
- <listitem><para>This is used to release the claim usbfs
- made on interface, either implicitly or because of a
- USBDEVFS_CLAIMINTERFACE call, before the file
- descriptor is closed.
- The ioctl parameter is an integer holding the number of
- the interface (bInterfaceNumber from descriptor);
- File modification time is not updated by this request.
- </para><warning><para>
- <emphasis>No security check is made to ensure
- that the task which made the claim is the one
- which is releasing it.
- This means that user mode driver may interfere
- other ones. </emphasis>
- </para></warning></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_RESETEP</term>
- <listitem><para>Resets the data toggle value for an endpoint
- (bulk or interrupt) to DATA0.
- The ioctl parameter is an integer endpoint number
- (1 to 15, as identified in the endpoint descriptor),
- with USB_DIR_IN added if the device's endpoint sends
- data to the host.
- </para><warning><para>
- <emphasis>Avoid using this request.
- It should probably be removed.</emphasis>
- Using it typically means the device and driver will lose
- toggle synchronization. If you really lost synchronization,
- you likely need to completely handshake with the device,
- using a request like CLEAR_HALT
- or SET_INTERFACE.
- </para></warning></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_DROP_PRIVILEGES</term>
- <listitem><para>This is used to relinquish the ability
- to do certain operations which are considered to be
- privileged on a usbfs file descriptor.
- This includes claiming arbitrary interfaces, resetting
- a device on which there are currently claimed interfaces
- from other users, and issuing USBDEVFS_IOCTL calls.
- The ioctl parameter is a 32 bit mask of interfaces
- the user is allowed to claim on this file descriptor.
- You may issue this ioctl more than one time to narrow
- said mask.
- </para></listitem></varlistentry>
- </variablelist>
-
- </sect2>
-
- <sect2 id="usbfs-sync">
- <title>Synchronous I/O Support</title>
-
- <para>Synchronous requests involve the kernel blocking
- until the user mode request completes, either by
- finishing successfully or by reporting an error.
- In most cases this is the simplest way to use usbfs,
- although as noted above it does prevent performing I/O
- to more than one endpoint at a time.
- </para>
-
- <variablelist>
-
- <varlistentry><term>USBDEVFS_BULK</term>
- <listitem><para>Issues a bulk read or write request to the
- device.
- The ioctl parameter is a pointer to this structure:
-<programlisting>struct usbdevfs_bulktransfer {
- unsigned int ep;
- unsigned int len;
- unsigned int timeout; /* in milliseconds */
- void *data;
-};</programlisting>
- </para><para>The "ep" value identifies a
- bulk endpoint number (1 to 15, as identified in an endpoint
- descriptor),
- masked with USB_DIR_IN when referring to an endpoint which
- sends data to the host from the device.
- The length of the data buffer is identified by "len";
- Recent kernels support requests up to about 128KBytes.
- <emphasis>FIXME say how read length is returned,
- and how short reads are handled.</emphasis>.
- </para></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_CLEAR_HALT</term>
- <listitem><para>Clears endpoint halt (stall) and
- resets the endpoint toggle. This is only
- meaningful for bulk or interrupt endpoints.
- The ioctl parameter is an integer endpoint number
- (1 to 15, as identified in an endpoint descriptor),
- masked with USB_DIR_IN when referring to an endpoint which
- sends data to the host from the device.
- </para><para>
- Use this on bulk or interrupt endpoints which have
- stalled, returning <emphasis>-EPIPE</emphasis> status
- to a data transfer request.
- Do not issue the control request directly, since
- that could invalidate the host's record of the
- data toggle.
- </para></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_CONTROL</term>
- <listitem><para>Issues a control request to the device.
- The ioctl parameter points to a structure like this:
-<programlisting>struct usbdevfs_ctrltransfer {
- __u8 bRequestType;
- __u8 bRequest;
- __u16 wValue;
- __u16 wIndex;
- __u16 wLength;
- __u32 timeout; /* in milliseconds */
- void *data;
-};</programlisting>
- </para><para>
- The first eight bytes of this structure are the contents
- of the SETUP packet to be sent to the device; see the
- USB 2.0 specification for details.
- The bRequestType value is composed by combining a
- USB_TYPE_* value, a USB_DIR_* value, and a
- USB_RECIP_* value (from
- <emphasis>&lt;linux/usb.h&gt;</emphasis>).
- If wLength is nonzero, it describes the length of the data
- buffer, which is either written to the device
- (USB_DIR_OUT) or read from the device (USB_DIR_IN).
- </para><para>
- At this writing, you can't transfer more than 4 KBytes
- of data to or from a device; usbfs has a limit, and
- some host controller drivers have a limit.
- (That's not usually a problem.)
- <emphasis>Also</emphasis> there's no way to say it's
- not OK to get a short read back from the device.
- </para></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_RESET</term>
- <listitem><para>Does a USB level device reset.
- The ioctl parameter is ignored.
- After the reset, this rebinds all device interfaces.
- File modification time is not updated by this request.
- </para><warning><para>
- <emphasis>Avoid using this call</emphasis>
- until some usbcore bugs get fixed,
- since it does not fully synchronize device, interface,
- and driver (not just usbfs) state.
- </para></warning></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_SETINTERFACE</term>
- <listitem><para>Sets the alternate setting for an
- interface. The ioctl parameter is a pointer to a
- structure like this:
-<programlisting>struct usbdevfs_setinterface {
- unsigned int interface;
- unsigned int altsetting;
-}; </programlisting>
- File modification time is not updated by this request.
- </para><para>
- Those struct members are from some interface descriptor
- applying to the current configuration.
- The interface number is the bInterfaceNumber value, and
- the altsetting number is the bAlternateSetting value.
- (This resets each endpoint in the interface.)
- </para></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_SETCONFIGURATION</term>
- <listitem><para>Issues the
- <function>usb_set_configuration</function> call
- for the device.
- The parameter is an integer holding the number of
- a configuration (bConfigurationValue from descriptor).
- File modification time is not updated by this request.
- </para><warning><para>
- <emphasis>Avoid using this call</emphasis>
- until some usbcore bugs get fixed,
- since it does not fully synchronize device, interface,
- and driver (not just usbfs) state.
- </para></warning></listitem></varlistentry>
-
- </variablelist>
- </sect2>
-
- <sect2 id="usbfs-async">
- <title>Asynchronous I/O Support</title>
-
- <para>As mentioned above, there are situations where it may be
- important to initiate concurrent operations from user mode code.
- This is particularly important for periodic transfers
- (interrupt and isochronous), but it can be used for other
- kinds of USB requests too.
- In such cases, the asynchronous requests described here
- are essential. Rather than submitting one request and having
- the kernel block until it completes, the blocking is separate.
- </para>
-
- <para>These requests are packaged into a structure that
- resembles the URB used by kernel device drivers.
- (No POSIX Async I/O support here, sorry.)
- It identifies the endpoint type (USBDEVFS_URB_TYPE_*),
- endpoint (number, masked with USB_DIR_IN as appropriate),
- buffer and length, and a user "context" value serving to
- uniquely identify each request.
- (It's usually a pointer to per-request data.)
- Flags can modify requests (not as many as supported for
- kernel drivers).
- </para>
-
- <para>Each request can specify a realtime signal number
- (between SIGRTMIN and SIGRTMAX, inclusive) to request a
- signal be sent when the request completes.
- </para>
-
- <para>When usbfs returns these urbs, the status value
- is updated, and the buffer may have been modified.
- Except for isochronous transfers, the actual_length is
- updated to say how many bytes were transferred; if the
- USBDEVFS_URB_DISABLE_SPD flag is set
- ("short packets are not OK"), if fewer bytes were read
- than were requested then you get an error report.
- </para>
-
-<programlisting>struct usbdevfs_iso_packet_desc {
- unsigned int length;
- unsigned int actual_length;
- unsigned int status;
-};
-
-struct usbdevfs_urb {
- unsigned char type;
- unsigned char endpoint;
- int status;
- unsigned int flags;
- void *buffer;
- int buffer_length;
- int actual_length;
- int start_frame;
- int number_of_packets;
- int error_count;
- unsigned int signr;
- void *usercontext;
- struct usbdevfs_iso_packet_desc iso_frame_desc[];
-};</programlisting>
-
- <para> For these asynchronous requests, the file modification
- time reflects when the request was initiated.
- This contrasts with their use with the synchronous requests,
- where it reflects when requests complete.
- </para>
-
- <variablelist>
-
- <varlistentry><term>USBDEVFS_DISCARDURB</term>
- <listitem><para>
- <emphasis>TBS</emphasis>
- File modification time is not updated by this request.
- </para><para>
- </para></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_DISCSIGNAL</term>
- <listitem><para>
- <emphasis>TBS</emphasis>
- File modification time is not updated by this request.
- </para><para>
- </para></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_REAPURB</term>
- <listitem><para>
- <emphasis>TBS</emphasis>
- File modification time is not updated by this request.
- </para><para>
- </para></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_REAPURBNDELAY</term>
- <listitem><para>
- <emphasis>TBS</emphasis>
- File modification time is not updated by this request.
- </para><para>
- </para></listitem></varlistentry>
-
- <varlistentry><term>USBDEVFS_SUBMITURB</term>
- <listitem><para>
- <emphasis>TBS</emphasis>
- </para><para>
- </para></listitem></varlistentry>
-
- </variablelist>
- </sect2>
-
- </sect1>
-
- </chapter>
-
-</book>
-<!-- vim:syntax=sgml:sw=4
--->
diff --git a/Documentation/DocBook/writing-an-alsa-driver.tmpl b/Documentation/DocBook/writing-an-alsa-driver.tmpl
deleted file mode 100644
index a27ab9f53fb6..000000000000
--- a/Documentation/DocBook/writing-an-alsa-driver.tmpl
+++ /dev/null
@@ -1,6206 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
- "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
-
-<!-- ****************************************************** -->
-<!-- Header -->
-<!-- ****************************************************** -->
-<book id="Writing-an-ALSA-Driver">
- <bookinfo>
- <title>Writing an ALSA Driver</title>
- <author>
- <firstname>Takashi</firstname>
- <surname>Iwai</surname>
- <affiliation>
- <address>
- <email>tiwai@suse.de</email>
- </address>
- </affiliation>
- </author>
-
- <date>Oct 15, 2007</date>
- <edition>0.3.7</edition>
-
- <abstract>
- <para>
- This document describes how to write an ALSA (Advanced Linux
- Sound Architecture) driver.
- </para>
- </abstract>
-
- <legalnotice>
- <para>
- Copyright (c) 2002-2005 Takashi Iwai <email>tiwai@suse.de</email>
- </para>
-
- <para>
- This document is free; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
- </para>
-
- <para>
- This document is distributed in the hope that it will be useful,
- but <emphasis>WITHOUT ANY WARRANTY</emphasis>; without even the
- implied warranty of <emphasis>MERCHANTABILITY or FITNESS FOR A
- PARTICULAR PURPOSE</emphasis>. See the GNU General Public License
- for more details.
- </para>
-
- <para>
- You should have received a copy of the GNU General Public
- License along with this program; if not, write to the Free
- Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
- MA 02111-1307 USA
- </para>
- </legalnotice>
-
- </bookinfo>
-
-<!-- ****************************************************** -->
-<!-- Preface -->
-<!-- ****************************************************** -->
- <preface id="preface">
- <title>Preface</title>
- <para>
- This document describes how to write an
- <ulink url="http://www.alsa-project.org/"><citetitle>
- ALSA (Advanced Linux Sound Architecture)</citetitle></ulink>
- driver. The document focuses mainly on PCI soundcards.
- In the case of other device types, the API might
- be different, too. However, at least the ALSA kernel API is
- consistent, and therefore it would be still a bit help for
- writing them.
- </para>
-
- <para>
- This document targets people who already have enough
- C language skills and have basic linux kernel programming
- knowledge. This document doesn't explain the general
- topic of linux kernel coding and doesn't cover low-level
- driver implementation details. It only describes
- the standard way to write a PCI sound driver on ALSA.
- </para>
-
- <para>
- If you are already familiar with the older ALSA ver.0.5.x API, you
- can check the drivers such as <filename>sound/pci/es1938.c</filename> or
- <filename>sound/pci/maestro3.c</filename> which have also almost the same
- code-base in the ALSA 0.5.x tree, so you can compare the differences.
- </para>
-
- <para>
- This document is still a draft version. Any feedback and
- corrections, please!!
- </para>
- </preface>
-
-
-<!-- ****************************************************** -->
-<!-- File Tree Structure -->
-<!-- ****************************************************** -->
- <chapter id="file-tree">
- <title>File Tree Structure</title>
-
- <section id="file-tree-general">
- <title>General</title>
- <para>
- The ALSA drivers are provided in two ways.
- </para>
-
- <para>
- One is the trees provided as a tarball or via cvs from the
- ALSA's ftp site, and another is the 2.6 (or later) Linux kernel
- tree. To synchronize both, the ALSA driver tree is split into
- two different trees: alsa-kernel and alsa-driver. The former
- contains purely the source code for the Linux 2.6 (or later)
- tree. This tree is designed only for compilation on 2.6 or
- later environment. The latter, alsa-driver, contains many subtle
- files for compiling ALSA drivers outside of the Linux kernel tree,
- wrapper functions for older 2.2 and 2.4 kernels, to adapt the latest kernel API,
- and additional drivers which are still in development or in
- tests. The drivers in alsa-driver tree will be moved to
- alsa-kernel (and eventually to the 2.6 kernel tree) when they are
- finished and confirmed to work fine.
- </para>
-
- <para>
- The file tree structure of ALSA driver is depicted below. Both
- alsa-kernel and alsa-driver have almost the same file
- structure, except for <quote>core</quote> directory. It's
- named as <quote>acore</quote> in alsa-driver tree.
-
- <example>
- <title>ALSA File Tree Structure</title>
- <literallayout>
- sound
- /core
- /oss
- /seq
- /oss
- /instr
- /ioctl32
- /include
- /drivers
- /mpu401
- /opl3
- /i2c
- /l3
- /synth
- /emux
- /pci
- /(cards)
- /isa
- /(cards)
- /arm
- /ppc
- /sparc
- /usb
- /pcmcia /(cards)
- /oss
- </literallayout>
- </example>
- </para>
- </section>
-
- <section id="file-tree-core-directory">
- <title>core directory</title>
- <para>
- This directory contains the middle layer which is the heart
- of ALSA drivers. In this directory, the native ALSA modules are
- stored. The sub-directories contain different modules and are
- dependent upon the kernel config.
- </para>
-
- <section id="file-tree-core-directory-oss">
- <title>core/oss</title>
-
- <para>
- The codes for PCM and mixer OSS emulation modules are stored
- in this directory. The rawmidi OSS emulation is included in
- the ALSA rawmidi code since it's quite small. The sequencer
- code is stored in <filename>core/seq/oss</filename> directory (see
- <link linkend="file-tree-core-directory-seq-oss"><citetitle>
- below</citetitle></link>).
- </para>
- </section>
-
- <section id="file-tree-core-directory-ioctl32">
- <title>core/ioctl32</title>
-
- <para>
- This directory contains the 32bit-ioctl wrappers for 64bit
- architectures such like x86-64, ppc64 and sparc64. For 32bit
- and alpha architectures, these are not compiled.
- </para>
- </section>
-
- <section id="file-tree-core-directory-seq">
- <title>core/seq</title>
- <para>
- This directory and its sub-directories are for the ALSA
- sequencer. This directory contains the sequencer core and
- primary sequencer modules such like snd-seq-midi,
- snd-seq-virmidi, etc. They are compiled only when
- <constant>CONFIG_SND_SEQUENCER</constant> is set in the kernel
- config.
- </para>
- </section>
-
- <section id="file-tree-core-directory-seq-oss">
- <title>core/seq/oss</title>
- <para>
- This contains the OSS sequencer emulation codes.
- </para>
- </section>
-
- <section id="file-tree-core-directory-deq-instr">
- <title>core/seq/instr</title>
- <para>
- This directory contains the modules for the sequencer
- instrument layer.
- </para>
- </section>
- </section>
-
- <section id="file-tree-include-directory">
- <title>include directory</title>
- <para>
- This is the place for the public header files of ALSA drivers,
- which are to be exported to user-space, or included by
- several files at different directories. Basically, the private
- header files should not be placed in this directory, but you may
- still find files there, due to historical reasons :)
- </para>
- </section>
-
- <section id="file-tree-drivers-directory">
- <title>drivers directory</title>
- <para>
- This directory contains code shared among different drivers
- on different architectures. They are hence supposed not to be
- architecture-specific.
- For example, the dummy pcm driver and the serial MIDI
- driver are found in this directory. In the sub-directories,
- there is code for components which are independent from
- bus and cpu architectures.
- </para>
-
- <section id="file-tree-drivers-directory-mpu401">
- <title>drivers/mpu401</title>
- <para>
- The MPU401 and MPU401-UART modules are stored here.
- </para>
- </section>
-
- <section id="file-tree-drivers-directory-opl3">
- <title>drivers/opl3 and opl4</title>
- <para>
- The OPL3 and OPL4 FM-synth stuff is found here.
- </para>
- </section>
- </section>
-
- <section id="file-tree-i2c-directory">
- <title>i2c directory</title>
- <para>
- This contains the ALSA i2c components.
- </para>
-
- <para>
- Although there is a standard i2c layer on Linux, ALSA has its
- own i2c code for some cards, because the soundcard needs only a
- simple operation and the standard i2c API is too complicated for
- such a purpose.
- </para>
-
- <section id="file-tree-i2c-directory-l3">
- <title>i2c/l3</title>
- <para>
- This is a sub-directory for ARM L3 i2c.
- </para>
- </section>
- </section>
-
- <section id="file-tree-synth-directory">
- <title>synth directory</title>
- <para>
- This contains the synth middle-level modules.
- </para>
-
- <para>
- So far, there is only Emu8000/Emu10k1 synth driver under
- the <filename>synth/emux</filename> sub-directory.
- </para>
- </section>
-
- <section id="file-tree-pci-directory">
- <title>pci directory</title>
- <para>
- This directory and its sub-directories hold the top-level card modules
- for PCI soundcards and the code specific to the PCI BUS.
- </para>
-
- <para>
- The drivers compiled from a single file are stored directly
- in the pci directory, while the drivers with several source files are
- stored on their own sub-directory (e.g. emu10k1, ice1712).
- </para>
- </section>
-
- <section id="file-tree-isa-directory">
- <title>isa directory</title>
- <para>
- This directory and its sub-directories hold the top-level card modules
- for ISA soundcards.
- </para>
- </section>
-
- <section id="file-tree-arm-ppc-sparc-directories">
- <title>arm, ppc, and sparc directories</title>
- <para>
- They are used for top-level card modules which are
- specific to one of these architectures.
- </para>
- </section>
-
- <section id="file-tree-usb-directory">
- <title>usb directory</title>
- <para>
- This directory contains the USB-audio driver. In the latest version, the
- USB MIDI driver is integrated in the usb-audio driver.
- </para>
- </section>
-
- <section id="file-tree-pcmcia-directory">
- <title>pcmcia directory</title>
- <para>
- The PCMCIA, especially PCCard drivers will go here. CardBus
- drivers will be in the pci directory, because their API is identical
- to that of standard PCI cards.
- </para>
- </section>
-
- <section id="file-tree-oss-directory">
- <title>oss directory</title>
- <para>
- The OSS/Lite source files are stored here in Linux 2.6 (or
- later) tree. In the ALSA driver tarball, this directory is empty,
- of course :)
- </para>
- </section>
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- Basic Flow for PCI Drivers -->
-<!-- ****************************************************** -->
- <chapter id="basic-flow">
- <title>Basic Flow for PCI Drivers</title>
-
- <section id="basic-flow-outline">
- <title>Outline</title>
- <para>
- The minimum flow for PCI soundcards is as follows:
-
- <itemizedlist>
- <listitem><para>define the PCI ID table (see the section
- <link linkend="pci-resource-entries"><citetitle>PCI Entries
- </citetitle></link>).</para></listitem>
- <listitem><para>create <function>probe()</function> callback.</para></listitem>
- <listitem><para>create <function>remove()</function> callback.</para></listitem>
- <listitem><para>create a <structname>pci_driver</structname> structure
- containing the three pointers above.</para></listitem>
- <listitem><para>create an <function>init()</function> function just calling
- the <function>pci_register_driver()</function> to register the pci_driver table
- defined above.</para></listitem>
- <listitem><para>create an <function>exit()</function> function to call
- the <function>pci_unregister_driver()</function> function.</para></listitem>
- </itemizedlist>
- </para>
- </section>
-
- <section id="basic-flow-example">
- <title>Full Code Example</title>
- <para>
- The code example is shown below. Some parts are kept
- unimplemented at this moment but will be filled in the
- next sections. The numbers in the comment lines of the
- <function>snd_mychip_probe()</function> function
- refer to details explained in the following section.
-
- <example>
- <title>Basic Flow for PCI Drivers - Example</title>
- <programlisting>
-<![CDATA[
- #include <linux/init.h>
- #include <linux/pci.h>
- #include <linux/slab.h>
- #include <sound/core.h>
- #include <sound/initval.h>
-
- /* module parameters (see "Module Parameters") */
- /* SNDRV_CARDS: maximum number of cards supported by this module */
- static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;
- static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;
- static bool enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE_PNP;
-
- /* definition of the chip-specific record */
- struct mychip {
- struct snd_card *card;
- /* the rest of the implementation will be in section
- * "PCI Resource Management"
- */
- };
-
- /* chip-specific destructor
- * (see "PCI Resource Management")
- */
- static int snd_mychip_free(struct mychip *chip)
- {
- .... /* will be implemented later... */
- }
-
- /* component-destructor
- * (see "Management of Cards and Components")
- */
- static int snd_mychip_dev_free(struct snd_device *device)
- {
- return snd_mychip_free(device->device_data);
- }
-
- /* chip-specific constructor
- * (see "Management of Cards and Components")
- */
- static int snd_mychip_create(struct snd_card *card,
- struct pci_dev *pci,
- struct mychip **rchip)
- {
- struct mychip *chip;
- int err;
- static struct snd_device_ops ops = {
- .dev_free = snd_mychip_dev_free,
- };
-
- *rchip = NULL;
-
- /* check PCI availability here
- * (see "PCI Resource Management")
- */
- ....
-
- /* allocate a chip-specific data with zero filled */
- chip = kzalloc(sizeof(*chip), GFP_KERNEL);
- if (chip == NULL)
- return -ENOMEM;
-
- chip->card = card;
-
- /* rest of initialization here; will be implemented
- * later, see "PCI Resource Management"
- */
- ....
-
- err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
- if (err < 0) {
- snd_mychip_free(chip);
- return err;
- }
-
- *rchip = chip;
- return 0;
- }
-
- /* constructor -- see "Constructor" sub-section */
- static int snd_mychip_probe(struct pci_dev *pci,
- const struct pci_device_id *pci_id)
- {
- static int dev;
- struct snd_card *card;
- struct mychip *chip;
- int err;
-
- /* (1) */
- if (dev >= SNDRV_CARDS)
- return -ENODEV;
- if (!enable[dev]) {
- dev++;
- return -ENOENT;
- }
-
- /* (2) */
- err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
- 0, &card);
- if (err < 0)
- return err;
-
- /* (3) */
- err = snd_mychip_create(card, pci, &chip);
- if (err < 0) {
- snd_card_free(card);
- return err;
- }
-
- /* (4) */
- strcpy(card->driver, "My Chip");
- strcpy(card->shortname, "My Own Chip 123");
- sprintf(card->longname, "%s at 0x%lx irq %i",
- card->shortname, chip->ioport, chip->irq);
-
- /* (5) */
- .... /* implemented later */
-
- /* (6) */
- err = snd_card_register(card);
- if (err < 0) {
- snd_card_free(card);
- return err;
- }
-
- /* (7) */
- pci_set_drvdata(pci, card);
- dev++;
- return 0;
- }
-
- /* destructor -- see the "Destructor" sub-section */
- static void snd_mychip_remove(struct pci_dev *pci)
- {
- snd_card_free(pci_get_drvdata(pci));
- pci_set_drvdata(pci, NULL);
- }
-]]>
- </programlisting>
- </example>
- </para>
- </section>
-
- <section id="basic-flow-constructor">
- <title>Constructor</title>
- <para>
- The real constructor of PCI drivers is the <function>probe</function> callback.
- The <function>probe</function> callback and other component-constructors which are called
- from the <function>probe</function> callback cannot be used with
- the <parameter>__init</parameter> prefix
- because any PCI device could be a hotplug device.
- </para>
-
- <para>
- In the <function>probe</function> callback, the following scheme is often used.
- </para>
-
- <section id="basic-flow-constructor-device-index">
- <title>1) Check and increment the device index.</title>
- <para>
- <informalexample>
- <programlisting>
-<![CDATA[
- static int dev;
- ....
- if (dev >= SNDRV_CARDS)
- return -ENODEV;
- if (!enable[dev]) {
- dev++;
- return -ENOENT;
- }
-]]>
- </programlisting>
- </informalexample>
-
- where enable[dev] is the module option.
- </para>
-
- <para>
- Each time the <function>probe</function> callback is called, check the
- availability of the device. If not available, simply increment
- the device index and returns. dev will be incremented also
- later (<link
- linkend="basic-flow-constructor-set-pci"><citetitle>step
- 7</citetitle></link>).
- </para>
- </section>
-
- <section id="basic-flow-constructor-create-card">
- <title>2) Create a card instance</title>
- <para>
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_card *card;
- int err;
- ....
- err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
- 0, &card);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The details will be explained in the section
- <link linkend="card-management-card-instance"><citetitle>
- Management of Cards and Components</citetitle></link>.
- </para>
- </section>
-
- <section id="basic-flow-constructor-create-main">
- <title>3) Create a main component</title>
- <para>
- In this part, the PCI resources are allocated.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct mychip *chip;
- ....
- err = snd_mychip_create(card, pci, &chip);
- if (err < 0) {
- snd_card_free(card);
- return err;
- }
-]]>
- </programlisting>
- </informalexample>
-
- The details will be explained in the section <link
- linkend="pci-resource"><citetitle>PCI Resource
- Management</citetitle></link>.
- </para>
- </section>
-
- <section id="basic-flow-constructor-main-component">
- <title>4) Set the driver ID and name strings.</title>
- <para>
- <informalexample>
- <programlisting>
-<![CDATA[
- strcpy(card->driver, "My Chip");
- strcpy(card->shortname, "My Own Chip 123");
- sprintf(card->longname, "%s at 0x%lx irq %i",
- card->shortname, chip->ioport, chip->irq);
-]]>
- </programlisting>
- </informalexample>
-
- The driver field holds the minimal ID string of the
- chip. This is used by alsa-lib's configurator, so keep it
- simple but unique.
- Even the same driver can have different driver IDs to
- distinguish the functionality of each chip type.
- </para>
-
- <para>
- The shortname field is a string shown as more verbose
- name. The longname field contains the information
- shown in <filename>/proc/asound/cards</filename>.
- </para>
- </section>
-
- <section id="basic-flow-constructor-create-other">
- <title>5) Create other components, such as mixer, MIDI, etc.</title>
- <para>
- Here you define the basic components such as
- <link linkend="pcm-interface"><citetitle>PCM</citetitle></link>,
- mixer (e.g. <link linkend="api-ac97"><citetitle>AC97</citetitle></link>),
- MIDI (e.g. <link linkend="midi-interface"><citetitle>MPU-401</citetitle></link>),
- and other interfaces.
- Also, if you want a <link linkend="proc-interface"><citetitle>proc
- file</citetitle></link>, define it here, too.
- </para>
- </section>
-
- <section id="basic-flow-constructor-register-card">
- <title>6) Register the card instance.</title>
- <para>
- <informalexample>
- <programlisting>
-<![CDATA[
- err = snd_card_register(card);
- if (err < 0) {
- snd_card_free(card);
- return err;
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- Will be explained in the section <link
- linkend="card-management-registration"><citetitle>Management
- of Cards and Components</citetitle></link>, too.
- </para>
- </section>
-
- <section id="basic-flow-constructor-set-pci">
- <title>7) Set the PCI driver data and return zero.</title>
- <para>
- <informalexample>
- <programlisting>
-<![CDATA[
- pci_set_drvdata(pci, card);
- dev++;
- return 0;
-]]>
- </programlisting>
- </informalexample>
-
- In the above, the card record is stored. This pointer is
- used in the remove callback and power-management
- callbacks, too.
- </para>
- </section>
- </section>
-
- <section id="basic-flow-destructor">
- <title>Destructor</title>
- <para>
- The destructor, remove callback, simply releases the card
- instance. Then the ALSA middle layer will release all the
- attached components automatically.
- </para>
-
- <para>
- It would be typically like the following:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static void snd_mychip_remove(struct pci_dev *pci)
- {
- snd_card_free(pci_get_drvdata(pci));
- pci_set_drvdata(pci, NULL);
- }
-]]>
- </programlisting>
- </informalexample>
-
- The above code assumes that the card pointer is set to the PCI
- driver data.
- </para>
- </section>
-
- <section id="basic-flow-header-files">
- <title>Header Files</title>
- <para>
- For the above example, at least the following include files
- are necessary.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- #include <linux/init.h>
- #include <linux/pci.h>
- #include <linux/slab.h>
- #include <sound/core.h>
- #include <sound/initval.h>
-]]>
- </programlisting>
- </informalexample>
-
- where the last one is necessary only when module options are
- defined in the source file. If the code is split into several
- files, the files without module options don't need them.
- </para>
-
- <para>
- In addition to these headers, you'll need
- <filename>&lt;linux/interrupt.h&gt;</filename> for interrupt
- handling, and <filename>&lt;asm/io.h&gt;</filename> for I/O
- access. If you use the <function>mdelay()</function> or
- <function>udelay()</function> functions, you'll need to include
- <filename>&lt;linux/delay.h&gt;</filename> too.
- </para>
-
- <para>
- The ALSA interfaces like the PCM and control APIs are defined in other
- <filename>&lt;sound/xxx.h&gt;</filename> header files.
- They have to be included after
- <filename>&lt;sound/core.h&gt;</filename>.
- </para>
-
- </section>
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- Management of Cards and Components -->
-<!-- ****************************************************** -->
- <chapter id="card-management">
- <title>Management of Cards and Components</title>
-
- <section id="card-management-card-instance">
- <title>Card Instance</title>
- <para>
- For each soundcard, a <quote>card</quote> record must be allocated.
- </para>
-
- <para>
- A card record is the headquarters of the soundcard. It manages
- the whole list of devices (components) on the soundcard, such as
- PCM, mixers, MIDI, synthesizer, and so on. Also, the card
- record holds the ID and the name strings of the card, manages
- the root of proc files, and controls the power-management states
- and hotplug disconnections. The component list on the card
- record is used to manage the correct release of resources at
- destruction.
- </para>
-
- <para>
- As mentioned above, to create a card instance, call
- <function>snd_card_new()</function>.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_card *card;
- int err;
- err = snd_card_new(&pci->dev, index, id, module, extra_size, &card);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The function takes six arguments: the parent device pointer,
- the card-index number, the id string, the module pointer (usually
- <constant>THIS_MODULE</constant>),
- the size of extra-data space, and the pointer to return the
- card instance. The extra_size argument is used to
- allocate card-&gt;private_data for the
- chip-specific data. Note that these data
- are allocated by <function>snd_card_new()</function>.
- </para>
-
- <para>
- The first argument, the pointer of struct
- <structname>device</structname>, specifies the parent device.
- For PCI devices, typically &amp;pci-&gt; is passed there.
- </para>
- </section>
-
- <section id="card-management-component">
- <title>Components</title>
- <para>
- After the card is created, you can attach the components
- (devices) to the card instance. In an ALSA driver, a component is
- represented as a struct <structname>snd_device</structname> object.
- A component can be a PCM instance, a control interface, a raw
- MIDI interface, etc. Each such instance has one component
- entry.
- </para>
-
- <para>
- A component can be created via
- <function>snd_device_new()</function> function.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_device_new(card, SNDRV_DEV_XXX, chip, &ops);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- This takes the card pointer, the device-level
- (<constant>SNDRV_DEV_XXX</constant>), the data pointer, and the
- callback pointers (<parameter>&amp;ops</parameter>). The
- device-level defines the type of components and the order of
- registration and de-registration. For most components, the
- device-level is already defined. For a user-defined component,
- you can use <constant>SNDRV_DEV_LOWLEVEL</constant>.
- </para>
-
- <para>
- This function itself doesn't allocate the data space. The data
- must be allocated manually beforehand, and its pointer is passed
- as the argument. This pointer (<parameter>chip</parameter> in the
- above example) is used as the identifier for the instance.
- </para>
-
- <para>
- Each pre-defined ALSA component such as ac97 and pcm calls
- <function>snd_device_new()</function> inside its
- constructor. The destructor for each component is defined in the
- callback pointers. Hence, you don't need to take care of
- calling a destructor for such a component.
- </para>
-
- <para>
- If you wish to create your own component, you need to
- set the destructor function to the dev_free callback in
- the <parameter>ops</parameter>, so that it can be released
- automatically via <function>snd_card_free()</function>.
- The next example will show an implementation of chip-specific
- data.
- </para>
- </section>
-
- <section id="card-management-chip-specific">
- <title>Chip-Specific Data</title>
- <para>
- Chip-specific information, e.g. the I/O port address, its
- resource pointer, or the irq number, is stored in the
- chip-specific record.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct mychip {
- ....
- };
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- In general, there are two ways of allocating the chip record.
- </para>
-
- <section id="card-management-chip-specific-snd-card-new">
- <title>1. Allocating via <function>snd_card_new()</function>.</title>
- <para>
- As mentioned above, you can pass the extra-data-length
- to the 5th argument of <function>snd_card_new()</function>, i.e.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
- sizeof(struct mychip), &card);
-]]>
- </programlisting>
- </informalexample>
-
- struct <structname>mychip</structname> is the type of the chip record.
- </para>
-
- <para>
- In return, the allocated record can be accessed as
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct mychip *chip = card->private_data;
-]]>
- </programlisting>
- </informalexample>
-
- With this method, you don't have to allocate twice.
- The record is released together with the card instance.
- </para>
- </section>
-
- <section id="card-management-chip-specific-allocate-extra">
- <title>2. Allocating an extra device.</title>
-
- <para>
- After allocating a card instance via
- <function>snd_card_new()</function> (with
- <constant>0</constant> on the 4th arg), call
- <function>kzalloc()</function>.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_card *card;
- struct mychip *chip;
- err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
- 0, &card);
- .....
- chip = kzalloc(sizeof(*chip), GFP_KERNEL);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The chip record should have the field to hold the card
- pointer at least,
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct mychip {
- struct snd_card *card;
- ....
- };
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- Then, set the card pointer in the returned chip instance.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- chip->card = card;
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- Next, initialize the fields, and register this chip
- record as a low-level device with a specified
- <parameter>ops</parameter>,
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static struct snd_device_ops ops = {
- .dev_free = snd_mychip_dev_free,
- };
- ....
- snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
-]]>
- </programlisting>
- </informalexample>
-
- <function>snd_mychip_dev_free()</function> is the
- device-destructor function, which will call the real
- destructor.
- </para>
-
- <para>
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_mychip_dev_free(struct snd_device *device)
- {
- return snd_mychip_free(device->device_data);
- }
-]]>
- </programlisting>
- </informalexample>
-
- where <function>snd_mychip_free()</function> is the real destructor.
- </para>
- </section>
- </section>
-
- <section id="card-management-registration">
- <title>Registration and Release</title>
- <para>
- After all components are assigned, register the card instance
- by calling <function>snd_card_register()</function>. Access
- to the device files is enabled at this point. That is, before
- <function>snd_card_register()</function> is called, the
- components are safely inaccessible from external side. If this
- call fails, exit the probe function after releasing the card via
- <function>snd_card_free()</function>.
- </para>
-
- <para>
- For releasing the card instance, you can call simply
- <function>snd_card_free()</function>. As mentioned earlier, all
- components are released automatically by this call.
- </para>
-
- <para>
- For a device which allows hotplugging, you can use
- <function>snd_card_free_when_closed</function>. This one will
- postpone the destruction until all devices are closed.
- </para>
-
- </section>
-
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- PCI Resource Management -->
-<!-- ****************************************************** -->
- <chapter id="pci-resource">
- <title>PCI Resource Management</title>
-
- <section id="pci-resource-example">
- <title>Full Code Example</title>
- <para>
- In this section, we'll complete the chip-specific constructor,
- destructor and PCI entries. Example code is shown first,
- below.
-
- <example>
- <title>PCI Resource Management Example</title>
- <programlisting>
-<![CDATA[
- struct mychip {
- struct snd_card *card;
- struct pci_dev *pci;
-
- unsigned long port;
- int irq;
- };
-
- static int snd_mychip_free(struct mychip *chip)
- {
- /* disable hardware here if any */
- .... /* (not implemented in this document) */
-
- /* release the irq */
- if (chip->irq >= 0)
- free_irq(chip->irq, chip);
- /* release the I/O ports & memory */
- pci_release_regions(chip->pci);
- /* disable the PCI entry */
- pci_disable_device(chip->pci);
- /* release the data */
- kfree(chip);
- return 0;
- }
-
- /* chip-specific constructor */
- static int snd_mychip_create(struct snd_card *card,
- struct pci_dev *pci,
- struct mychip **rchip)
- {
- struct mychip *chip;
- int err;
- static struct snd_device_ops ops = {
- .dev_free = snd_mychip_dev_free,
- };
-
- *rchip = NULL;
-
- /* initialize the PCI entry */
- err = pci_enable_device(pci);
- if (err < 0)
- return err;
- /* check PCI availability (28bit DMA) */
- if (pci_set_dma_mask(pci, DMA_BIT_MASK(28)) < 0 ||
- pci_set_consistent_dma_mask(pci, DMA_BIT_MASK(28)) < 0) {
- printk(KERN_ERR "error to set 28bit mask DMA\n");
- pci_disable_device(pci);
- return -ENXIO;
- }
-
- chip = kzalloc(sizeof(*chip), GFP_KERNEL);
- if (chip == NULL) {
- pci_disable_device(pci);
- return -ENOMEM;
- }
-
- /* initialize the stuff */
- chip->card = card;
- chip->pci = pci;
- chip->irq = -1;
-
- /* (1) PCI resource allocation */
- err = pci_request_regions(pci, "My Chip");
- if (err < 0) {
- kfree(chip);
- pci_disable_device(pci);
- return err;
- }
- chip->port = pci_resource_start(pci, 0);
- if (request_irq(pci->irq, snd_mychip_interrupt,
- IRQF_SHARED, KBUILD_MODNAME, chip)) {
- printk(KERN_ERR "cannot grab irq %d\n", pci->irq);
- snd_mychip_free(chip);
- return -EBUSY;
- }
- chip->irq = pci->irq;
-
- /* (2) initialization of the chip hardware */
- .... /* (not implemented in this document) */
-
- err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, chip, &ops);
- if (err < 0) {
- snd_mychip_free(chip);
- return err;
- }
-
- *rchip = chip;
- return 0;
- }
-
- /* PCI IDs */
- static struct pci_device_id snd_mychip_ids[] = {
- { PCI_VENDOR_ID_FOO, PCI_DEVICE_ID_BAR,
- PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
- ....
- { 0, }
- };
- MODULE_DEVICE_TABLE(pci, snd_mychip_ids);
-
- /* pci_driver definition */
- static struct pci_driver driver = {
- .name = KBUILD_MODNAME,
- .id_table = snd_mychip_ids,
- .probe = snd_mychip_probe,
- .remove = snd_mychip_remove,
- };
-
- /* module initialization */
- static int __init alsa_card_mychip_init(void)
- {
- return pci_register_driver(&driver);
- }
-
- /* module clean up */
- static void __exit alsa_card_mychip_exit(void)
- {
- pci_unregister_driver(&driver);
- }
-
- module_init(alsa_card_mychip_init)
- module_exit(alsa_card_mychip_exit)
-
- EXPORT_NO_SYMBOLS; /* for old kernels only */
-]]>
- </programlisting>
- </example>
- </para>
- </section>
-
- <section id="pci-resource-some-haftas">
- <title>Some Hafta's</title>
- <para>
- The allocation of PCI resources is done in the
- <function>probe()</function> function, and usually an extra
- <function>xxx_create()</function> function is written for this
- purpose.
- </para>
-
- <para>
- In the case of PCI devices, you first have to call
- the <function>pci_enable_device()</function> function before
- allocating resources. Also, you need to set the proper PCI DMA
- mask to limit the accessed I/O range. In some cases, you might
- need to call <function>pci_set_master()</function> function,
- too.
- </para>
-
- <para>
- Suppose the 28bit mask, and the code to be added would be like:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- err = pci_enable_device(pci);
- if (err < 0)
- return err;
- if (pci_set_dma_mask(pci, DMA_BIT_MASK(28)) < 0 ||
- pci_set_consistent_dma_mask(pci, DMA_BIT_MASK(28)) < 0) {
- printk(KERN_ERR "error to set 28bit mask DMA\n");
- pci_disable_device(pci);
- return -ENXIO;
- }
-
-]]>
- </programlisting>
- </informalexample>
- </para>
- </section>
-
- <section id="pci-resource-resource-allocation">
- <title>Resource Allocation</title>
- <para>
- The allocation of I/O ports and irqs is done via standard kernel
- functions. Unlike ALSA ver.0.5.x., there are no helpers for
- that. And these resources must be released in the destructor
- function (see below). Also, on ALSA 0.9.x, you don't need to
- allocate (pseudo-)DMA for PCI like in ALSA 0.5.x.
- </para>
-
- <para>
- Now assume that the PCI device has an I/O port with 8 bytes
- and an interrupt. Then struct <structname>mychip</structname> will have the
- following fields:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct mychip {
- struct snd_card *card;
-
- unsigned long port;
- int irq;
- };
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- For an I/O port (and also a memory region), you need to have
- the resource pointer for the standard resource management. For
- an irq, you have to keep only the irq number (integer). But you
- need to initialize this number as -1 before actual allocation,
- since irq 0 is valid. The port address and its resource pointer
- can be initialized as null by
- <function>kzalloc()</function> automatically, so you
- don't have to take care of resetting them.
- </para>
-
- <para>
- The allocation of an I/O port is done like this:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- err = pci_request_regions(pci, "My Chip");
- if (err < 0) {
- kfree(chip);
- pci_disable_device(pci);
- return err;
- }
- chip->port = pci_resource_start(pci, 0);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- <!-- obsolete -->
- It will reserve the I/O port region of 8 bytes of the given
- PCI device. The returned value, chip-&gt;res_port, is allocated
- via <function>kmalloc()</function> by
- <function>request_region()</function>. The pointer must be
- released via <function>kfree()</function>, but there is a
- problem with this. This issue will be explained later.
- </para>
-
- <para>
- The allocation of an interrupt source is done like this:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- if (request_irq(pci->irq, snd_mychip_interrupt,
- IRQF_SHARED, KBUILD_MODNAME, chip)) {
- printk(KERN_ERR "cannot grab irq %d\n", pci->irq);
- snd_mychip_free(chip);
- return -EBUSY;
- }
- chip->irq = pci->irq;
-]]>
- </programlisting>
- </informalexample>
-
- where <function>snd_mychip_interrupt()</function> is the
- interrupt handler defined <link
- linkend="pcm-interface-interrupt-handler"><citetitle>later</citetitle></link>.
- Note that chip-&gt;irq should be defined
- only when <function>request_irq()</function> succeeded.
- </para>
-
- <para>
- On the PCI bus, interrupts can be shared. Thus,
- <constant>IRQF_SHARED</constant> is used as the interrupt flag of
- <function>request_irq()</function>.
- </para>
-
- <para>
- The last argument of <function>request_irq()</function> is the
- data pointer passed to the interrupt handler. Usually, the
- chip-specific record is used for that, but you can use what you
- like, too.
- </para>
-
- <para>
- I won't give details about the interrupt handler at this
- point, but at least its appearance can be explained now. The
- interrupt handler looks usually like the following:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static irqreturn_t snd_mychip_interrupt(int irq, void *dev_id)
- {
- struct mychip *chip = dev_id;
- ....
- return IRQ_HANDLED;
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- Now let's write the corresponding destructor for the resources
- above. The role of destructor is simple: disable the hardware
- (if already activated) and release the resources. So far, we
- have no hardware part, so the disabling code is not written here.
- </para>
-
- <para>
- To release the resources, the <quote>check-and-release</quote>
- method is a safer way. For the interrupt, do like this:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- if (chip->irq >= 0)
- free_irq(chip->irq, chip);
-]]>
- </programlisting>
- </informalexample>
-
- Since the irq number can start from 0, you should initialize
- chip-&gt;irq with a negative value (e.g. -1), so that you can
- check the validity of the irq number as above.
- </para>
-
- <para>
- When you requested I/O ports or memory regions via
- <function>pci_request_region()</function> or
- <function>pci_request_regions()</function> like in this example,
- release the resource(s) using the corresponding function,
- <function>pci_release_region()</function> or
- <function>pci_release_regions()</function>.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- pci_release_regions(chip->pci);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- When you requested manually via <function>request_region()</function>
- or <function>request_mem_region</function>, you can release it via
- <function>release_resource()</function>. Suppose that you keep
- the resource pointer returned from <function>request_region()</function>
- in chip-&gt;res_port, the release procedure looks like:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- release_and_free_resource(chip->res_port);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- Don't forget to call <function>pci_disable_device()</function>
- before the end.
- </para>
-
- <para>
- And finally, release the chip-specific record.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- kfree(chip);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- We didn't implement the hardware disabling part in the above.
- If you need to do this, please note that the destructor may be
- called even before the initialization of the chip is completed.
- It would be better to have a flag to skip hardware disabling
- if the hardware was not initialized yet.
- </para>
-
- <para>
- When the chip-data is assigned to the card using
- <function>snd_device_new()</function> with
- <constant>SNDRV_DEV_LOWLELVEL</constant> , its destructor is
- called at the last. That is, it is assured that all other
- components like PCMs and controls have already been released.
- You don't have to stop PCMs, etc. explicitly, but just
- call low-level hardware stopping.
- </para>
-
- <para>
- The management of a memory-mapped region is almost as same as
- the management of an I/O port. You'll need three fields like
- the following:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct mychip {
- ....
- unsigned long iobase_phys;
- void __iomem *iobase_virt;
- };
-]]>
- </programlisting>
- </informalexample>
-
- and the allocation would be like below:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- if ((err = pci_request_regions(pci, "My Chip")) < 0) {
- kfree(chip);
- return err;
- }
- chip->iobase_phys = pci_resource_start(pci, 0);
- chip->iobase_virt = ioremap_nocache(chip->iobase_phys,
- pci_resource_len(pci, 0));
-]]>
- </programlisting>
- </informalexample>
-
- and the corresponding destructor would be:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_mychip_free(struct mychip *chip)
- {
- ....
- if (chip->iobase_virt)
- iounmap(chip->iobase_virt);
- ....
- pci_release_regions(chip->pci);
- ....
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- </section>
-
- <section id="pci-resource-entries">
- <title>PCI Entries</title>
- <para>
- So far, so good. Let's finish the missing PCI
- stuff. At first, we need a
- <structname>pci_device_id</structname> table for this
- chipset. It's a table of PCI vendor/device ID number, and some
- masks.
- </para>
-
- <para>
- For example,
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static struct pci_device_id snd_mychip_ids[] = {
- { PCI_VENDOR_ID_FOO, PCI_DEVICE_ID_BAR,
- PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
- ....
- { 0, }
- };
- MODULE_DEVICE_TABLE(pci, snd_mychip_ids);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The first and second fields of
- the <structname>pci_device_id</structname> structure are the vendor and
- device IDs. If you have no reason to filter the matching
- devices, you can leave the remaining fields as above. The last
- field of the <structname>pci_device_id</structname> struct contains
- private data for this entry. You can specify any value here, for
- example, to define specific operations for supported device IDs.
- Such an example is found in the intel8x0 driver.
- </para>
-
- <para>
- The last entry of this list is the terminator. You must
- specify this all-zero entry.
- </para>
-
- <para>
- Then, prepare the <structname>pci_driver</structname> record:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static struct pci_driver driver = {
- .name = KBUILD_MODNAME,
- .id_table = snd_mychip_ids,
- .probe = snd_mychip_probe,
- .remove = snd_mychip_remove,
- };
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The <structfield>probe</structfield> and
- <structfield>remove</structfield> functions have already
- been defined in the previous sections.
- The <structfield>name</structfield>
- field is the name string of this device. Note that you must not
- use a slash <quote>/</quote> in this string.
- </para>
-
- <para>
- And at last, the module entries:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int __init alsa_card_mychip_init(void)
- {
- return pci_register_driver(&driver);
- }
-
- static void __exit alsa_card_mychip_exit(void)
- {
- pci_unregister_driver(&driver);
- }
-
- module_init(alsa_card_mychip_init)
- module_exit(alsa_card_mychip_exit)
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- Note that these module entries are tagged with
- <parameter>__init</parameter> and
- <parameter>__exit</parameter> prefixes.
- </para>
-
- <para>
- Oh, one thing was forgotten. If you have no exported symbols,
- you need to declare it in 2.2 or 2.4 kernels (it's not necessary in 2.6 kernels).
-
- <informalexample>
- <programlisting>
-<![CDATA[
- EXPORT_NO_SYMBOLS;
-]]>
- </programlisting>
- </informalexample>
-
- That's all!
- </para>
- </section>
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- PCM Interface -->
-<!-- ****************************************************** -->
- <chapter id="pcm-interface">
- <title>PCM Interface</title>
-
- <section id="pcm-interface-general">
- <title>General</title>
- <para>
- The PCM middle layer of ALSA is quite powerful and it is only
- necessary for each driver to implement the low-level functions
- to access its hardware.
- </para>
-
- <para>
- For accessing to the PCM layer, you need to include
- <filename>&lt;sound/pcm.h&gt;</filename> first. In addition,
- <filename>&lt;sound/pcm_params.h&gt;</filename> might be needed
- if you access to some functions related with hw_param.
- </para>
-
- <para>
- Each card device can have up to four pcm instances. A pcm
- instance corresponds to a pcm device file. The limitation of
- number of instances comes only from the available bit size of
- the Linux's device numbers. Once when 64bit device number is
- used, we'll have more pcm instances available.
- </para>
-
- <para>
- A pcm instance consists of pcm playback and capture streams,
- and each pcm stream consists of one or more pcm substreams. Some
- soundcards support multiple playback functions. For example,
- emu10k1 has a PCM playback of 32 stereo substreams. In this case, at
- each open, a free substream is (usually) automatically chosen
- and opened. Meanwhile, when only one substream exists and it was
- already opened, the successful open will either block
- or error with <constant>EAGAIN</constant> according to the
- file open mode. But you don't have to care about such details in your
- driver. The PCM middle layer will take care of such work.
- </para>
- </section>
-
- <section id="pcm-interface-example">
- <title>Full Code Example</title>
- <para>
- The example code below does not include any hardware access
- routines but shows only the skeleton, how to build up the PCM
- interfaces.
-
- <example>
- <title>PCM Example Code</title>
- <programlisting>
-<![CDATA[
- #include <sound/pcm.h>
- ....
-
- /* hardware definition */
- static struct snd_pcm_hardware snd_mychip_playback_hw = {
- .info = (SNDRV_PCM_INFO_MMAP |
- SNDRV_PCM_INFO_INTERLEAVED |
- SNDRV_PCM_INFO_BLOCK_TRANSFER |
- SNDRV_PCM_INFO_MMAP_VALID),
- .formats = SNDRV_PCM_FMTBIT_S16_LE,
- .rates = SNDRV_PCM_RATE_8000_48000,
- .rate_min = 8000,
- .rate_max = 48000,
- .channels_min = 2,
- .channels_max = 2,
- .buffer_bytes_max = 32768,
- .period_bytes_min = 4096,
- .period_bytes_max = 32768,
- .periods_min = 1,
- .periods_max = 1024,
- };
-
- /* hardware definition */
- static struct snd_pcm_hardware snd_mychip_capture_hw = {
- .info = (SNDRV_PCM_INFO_MMAP |
- SNDRV_PCM_INFO_INTERLEAVED |
- SNDRV_PCM_INFO_BLOCK_TRANSFER |
- SNDRV_PCM_INFO_MMAP_VALID),
- .formats = SNDRV_PCM_FMTBIT_S16_LE,
- .rates = SNDRV_PCM_RATE_8000_48000,
- .rate_min = 8000,
- .rate_max = 48000,
- .channels_min = 2,
- .channels_max = 2,
- .buffer_bytes_max = 32768,
- .period_bytes_min = 4096,
- .period_bytes_max = 32768,
- .periods_min = 1,
- .periods_max = 1024,
- };
-
- /* open callback */
- static int snd_mychip_playback_open(struct snd_pcm_substream *substream)
- {
- struct mychip *chip = snd_pcm_substream_chip(substream);
- struct snd_pcm_runtime *runtime = substream->runtime;
-
- runtime->hw = snd_mychip_playback_hw;
- /* more hardware-initialization will be done here */
- ....
- return 0;
- }
-
- /* close callback */
- static int snd_mychip_playback_close(struct snd_pcm_substream *substream)
- {
- struct mychip *chip = snd_pcm_substream_chip(substream);
- /* the hardware-specific codes will be here */
- ....
- return 0;
-
- }
-
- /* open callback */
- static int snd_mychip_capture_open(struct snd_pcm_substream *substream)
- {
- struct mychip *chip = snd_pcm_substream_chip(substream);
- struct snd_pcm_runtime *runtime = substream->runtime;
-
- runtime->hw = snd_mychip_capture_hw;
- /* more hardware-initialization will be done here */
- ....
- return 0;
- }
-
- /* close callback */
- static int snd_mychip_capture_close(struct snd_pcm_substream *substream)
- {
- struct mychip *chip = snd_pcm_substream_chip(substream);
- /* the hardware-specific codes will be here */
- ....
- return 0;
-
- }
-
- /* hw_params callback */
- static int snd_mychip_pcm_hw_params(struct snd_pcm_substream *substream,
- struct snd_pcm_hw_params *hw_params)
- {
- return snd_pcm_lib_malloc_pages(substream,
- params_buffer_bytes(hw_params));
- }
-
- /* hw_free callback */
- static int snd_mychip_pcm_hw_free(struct snd_pcm_substream *substream)
- {
- return snd_pcm_lib_free_pages(substream);
- }
-
- /* prepare callback */
- static int snd_mychip_pcm_prepare(struct snd_pcm_substream *substream)
- {
- struct mychip *chip = snd_pcm_substream_chip(substream);
- struct snd_pcm_runtime *runtime = substream->runtime;
-
- /* set up the hardware with the current configuration
- * for example...
- */
- mychip_set_sample_format(chip, runtime->format);
- mychip_set_sample_rate(chip, runtime->rate);
- mychip_set_channels(chip, runtime->channels);
- mychip_set_dma_setup(chip, runtime->dma_addr,
- chip->buffer_size,
- chip->period_size);
- return 0;
- }
-
- /* trigger callback */
- static int snd_mychip_pcm_trigger(struct snd_pcm_substream *substream,
- int cmd)
- {
- switch (cmd) {
- case SNDRV_PCM_TRIGGER_START:
- /* do something to start the PCM engine */
- ....
- break;
- case SNDRV_PCM_TRIGGER_STOP:
- /* do something to stop the PCM engine */
- ....
- break;
- default:
- return -EINVAL;
- }
- }
-
- /* pointer callback */
- static snd_pcm_uframes_t
- snd_mychip_pcm_pointer(struct snd_pcm_substream *substream)
- {
- struct mychip *chip = snd_pcm_substream_chip(substream);
- unsigned int current_ptr;
-
- /* get the current hardware pointer */
- current_ptr = mychip_get_hw_pointer(chip);
- return current_ptr;
- }
-
- /* operators */
- static struct snd_pcm_ops snd_mychip_playback_ops = {
- .open = snd_mychip_playback_open,
- .close = snd_mychip_playback_close,
- .ioctl = snd_pcm_lib_ioctl,
- .hw_params = snd_mychip_pcm_hw_params,
- .hw_free = snd_mychip_pcm_hw_free,
- .prepare = snd_mychip_pcm_prepare,
- .trigger = snd_mychip_pcm_trigger,
- .pointer = snd_mychip_pcm_pointer,
- };
-
- /* operators */
- static struct snd_pcm_ops snd_mychip_capture_ops = {
- .open = snd_mychip_capture_open,
- .close = snd_mychip_capture_close,
- .ioctl = snd_pcm_lib_ioctl,
- .hw_params = snd_mychip_pcm_hw_params,
- .hw_free = snd_mychip_pcm_hw_free,
- .prepare = snd_mychip_pcm_prepare,
- .trigger = snd_mychip_pcm_trigger,
- .pointer = snd_mychip_pcm_pointer,
- };
-
- /*
- * definitions of capture are omitted here...
- */
-
- /* create a pcm device */
- static int snd_mychip_new_pcm(struct mychip *chip)
- {
- struct snd_pcm *pcm;
- int err;
-
- err = snd_pcm_new(chip->card, "My Chip", 0, 1, 1, &pcm);
- if (err < 0)
- return err;
- pcm->private_data = chip;
- strcpy(pcm->name, "My Chip");
- chip->pcm = pcm;
- /* set operators */
- snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK,
- &snd_mychip_playback_ops);
- snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE,
- &snd_mychip_capture_ops);
- /* pre-allocation of buffers */
- /* NOTE: this may fail */
- snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV,
- snd_dma_pci_data(chip->pci),
- 64*1024, 64*1024);
- return 0;
- }
-]]>
- </programlisting>
- </example>
- </para>
- </section>
-
- <section id="pcm-interface-constructor">
- <title>Constructor</title>
- <para>
- A pcm instance is allocated by the <function>snd_pcm_new()</function>
- function. It would be better to create a constructor for pcm,
- namely,
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_mychip_new_pcm(struct mychip *chip)
- {
- struct snd_pcm *pcm;
- int err;
-
- err = snd_pcm_new(chip->card, "My Chip", 0, 1, 1, &pcm);
- if (err < 0)
- return err;
- pcm->private_data = chip;
- strcpy(pcm->name, "My Chip");
- chip->pcm = pcm;
- ....
- return 0;
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The <function>snd_pcm_new()</function> function takes four
- arguments. The first argument is the card pointer to which this
- pcm is assigned, and the second is the ID string.
- </para>
-
- <para>
- The third argument (<parameter>index</parameter>, 0 in the
- above) is the index of this new pcm. It begins from zero. If
- you create more than one pcm instances, specify the
- different numbers in this argument. For example,
- <parameter>index</parameter> = 1 for the second PCM device.
- </para>
-
- <para>
- The fourth and fifth arguments are the number of substreams
- for playback and capture, respectively. Here 1 is used for
- both arguments. When no playback or capture substreams are available,
- pass 0 to the corresponding argument.
- </para>
-
- <para>
- If a chip supports multiple playbacks or captures, you can
- specify more numbers, but they must be handled properly in
- open/close, etc. callbacks. When you need to know which
- substream you are referring to, then it can be obtained from
- struct <structname>snd_pcm_substream</structname> data passed to each callback
- as follows:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_pcm_substream *substream;
- int index = substream->number;
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- After the pcm is created, you need to set operators for each
- pcm stream.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK,
- &snd_mychip_playback_ops);
- snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE,
- &snd_mychip_capture_ops);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The operators are defined typically like this:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static struct snd_pcm_ops snd_mychip_playback_ops = {
- .open = snd_mychip_pcm_open,
- .close = snd_mychip_pcm_close,
- .ioctl = snd_pcm_lib_ioctl,
- .hw_params = snd_mychip_pcm_hw_params,
- .hw_free = snd_mychip_pcm_hw_free,
- .prepare = snd_mychip_pcm_prepare,
- .trigger = snd_mychip_pcm_trigger,
- .pointer = snd_mychip_pcm_pointer,
- };
-]]>
- </programlisting>
- </informalexample>
-
- All the callbacks are described in the
- <link linkend="pcm-interface-operators"><citetitle>
- Operators</citetitle></link> subsection.
- </para>
-
- <para>
- After setting the operators, you probably will want to
- pre-allocate the buffer. For the pre-allocation, simply call
- the following:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV,
- snd_dma_pci_data(chip->pci),
- 64*1024, 64*1024);
-]]>
- </programlisting>
- </informalexample>
-
- It will allocate a buffer up to 64kB as default.
- Buffer management details will be described in the later section <link
- linkend="buffer-and-memory"><citetitle>Buffer and Memory
- Management</citetitle></link>.
- </para>
-
- <para>
- Additionally, you can set some extra information for this pcm
- in pcm-&gt;info_flags.
- The available values are defined as
- <constant>SNDRV_PCM_INFO_XXX</constant> in
- <filename>&lt;sound/asound.h&gt;</filename>, which is used for
- the hardware definition (described later). When your soundchip
- supports only half-duplex, specify like this:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- pcm->info_flags = SNDRV_PCM_INFO_HALF_DUPLEX;
-]]>
- </programlisting>
- </informalexample>
- </para>
- </section>
-
- <section id="pcm-interface-destructor">
- <title>... And the Destructor?</title>
- <para>
- The destructor for a pcm instance is not always
- necessary. Since the pcm device will be released by the middle
- layer code automatically, you don't have to call the destructor
- explicitly.
- </para>
-
- <para>
- The destructor would be necessary if you created
- special records internally and needed to release them. In such a
- case, set the destructor function to
- pcm-&gt;private_free:
-
- <example>
- <title>PCM Instance with a Destructor</title>
- <programlisting>
-<![CDATA[
- static void mychip_pcm_free(struct snd_pcm *pcm)
- {
- struct mychip *chip = snd_pcm_chip(pcm);
- /* free your own data */
- kfree(chip->my_private_pcm_data);
- /* do what you like else */
- ....
- }
-
- static int snd_mychip_new_pcm(struct mychip *chip)
- {
- struct snd_pcm *pcm;
- ....
- /* allocate your own data */
- chip->my_private_pcm_data = kmalloc(...);
- /* set the destructor */
- pcm->private_data = chip;
- pcm->private_free = mychip_pcm_free;
- ....
- }
-]]>
- </programlisting>
- </example>
- </para>
- </section>
-
- <section id="pcm-interface-runtime">
- <title>Runtime Pointer - The Chest of PCM Information</title>
- <para>
- When the PCM substream is opened, a PCM runtime instance is
- allocated and assigned to the substream. This pointer is
- accessible via <constant>substream-&gt;runtime</constant>.
- This runtime pointer holds most information you need
- to control the PCM: the copy of hw_params and sw_params configurations, the buffer
- pointers, mmap records, spinlocks, etc.
- </para>
-
- <para>
- The definition of runtime instance is found in
- <filename>&lt;sound/pcm.h&gt;</filename>. Here are
- the contents of this file:
- <informalexample>
- <programlisting>
-<![CDATA[
-struct _snd_pcm_runtime {
- /* -- Status -- */
- struct snd_pcm_substream *trigger_master;
- snd_timestamp_t trigger_tstamp; /* trigger timestamp */
- int overrange;
- snd_pcm_uframes_t avail_max;
- snd_pcm_uframes_t hw_ptr_base; /* Position at buffer restart */
- snd_pcm_uframes_t hw_ptr_interrupt; /* Position at interrupt time*/
-
- /* -- HW params -- */
- snd_pcm_access_t access; /* access mode */
- snd_pcm_format_t format; /* SNDRV_PCM_FORMAT_* */
- snd_pcm_subformat_t subformat; /* subformat */
- unsigned int rate; /* rate in Hz */
- unsigned int channels; /* channels */
- snd_pcm_uframes_t period_size; /* period size */
- unsigned int periods; /* periods */
- snd_pcm_uframes_t buffer_size; /* buffer size */
- unsigned int tick_time; /* tick time */
- snd_pcm_uframes_t min_align; /* Min alignment for the format */
- size_t byte_align;
- unsigned int frame_bits;
- unsigned int sample_bits;
- unsigned int info;
- unsigned int rate_num;
- unsigned int rate_den;
-
- /* -- SW params -- */
- struct timespec tstamp_mode; /* mmap timestamp is updated */
- unsigned int period_step;
- unsigned int sleep_min; /* min ticks to sleep */
- snd_pcm_uframes_t start_threshold;
- snd_pcm_uframes_t stop_threshold;
- snd_pcm_uframes_t silence_threshold; /* Silence filling happens when
- noise is nearest than this */
- snd_pcm_uframes_t silence_size; /* Silence filling size */
- snd_pcm_uframes_t boundary; /* pointers wrap point */
-
- snd_pcm_uframes_t silenced_start;
- snd_pcm_uframes_t silenced_size;
-
- snd_pcm_sync_id_t sync; /* hardware synchronization ID */
-
- /* -- mmap -- */
- volatile struct snd_pcm_mmap_status *status;
- volatile struct snd_pcm_mmap_control *control;
- atomic_t mmap_count;
-
- /* -- locking / scheduling -- */
- spinlock_t lock;
- wait_queue_head_t sleep;
- struct timer_list tick_timer;
- struct fasync_struct *fasync;
-
- /* -- private section -- */
- void *private_data;
- void (*private_free)(struct snd_pcm_runtime *runtime);
-
- /* -- hardware description -- */
- struct snd_pcm_hardware hw;
- struct snd_pcm_hw_constraints hw_constraints;
-
- /* -- timer -- */
- unsigned int timer_resolution; /* timer resolution */
-
- /* -- DMA -- */
- unsigned char *dma_area; /* DMA area */
- dma_addr_t dma_addr; /* physical bus address (not accessible from main CPU) */
- size_t dma_bytes; /* size of DMA area */
-
- struct snd_dma_buffer *dma_buffer_p; /* allocated buffer */
-
-#if defined(CONFIG_SND_PCM_OSS) || defined(CONFIG_SND_PCM_OSS_MODULE)
- /* -- OSS things -- */
- struct snd_pcm_oss_runtime oss;
-#endif
-};
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- For the operators (callbacks) of each sound driver, most of
- these records are supposed to be read-only. Only the PCM
- middle-layer changes / updates them. The exceptions are
- the hardware description (hw) DMA buffer information and the
- private data. Besides, if you use the standard buffer allocation
- method via <function>snd_pcm_lib_malloc_pages()</function>,
- you don't need to set the DMA buffer information by yourself.
- </para>
-
- <para>
- In the sections below, important records are explained.
- </para>
-
- <section id="pcm-interface-runtime-hw">
- <title>Hardware Description</title>
- <para>
- The hardware descriptor (struct <structname>snd_pcm_hardware</structname>)
- contains the definitions of the fundamental hardware
- configuration. Above all, you'll need to define this in
- <link linkend="pcm-interface-operators-open-callback"><citetitle>
- the open callback</citetitle></link>.
- Note that the runtime instance holds the copy of the
- descriptor, not the pointer to the existing descriptor. That
- is, in the open callback, you can modify the copied descriptor
- (<constant>runtime-&gt;hw</constant>) as you need. For example, if the maximum
- number of channels is 1 only on some chip models, you can
- still use the same hardware descriptor and change the
- channels_max later:
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_pcm_runtime *runtime = substream->runtime;
- ...
- runtime->hw = snd_mychip_playback_hw; /* common definition */
- if (chip->model == VERY_OLD_ONE)
- runtime->hw.channels_max = 1;
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- Typically, you'll have a hardware descriptor as below:
- <informalexample>
- <programlisting>
-<![CDATA[
- static struct snd_pcm_hardware snd_mychip_playback_hw = {
- .info = (SNDRV_PCM_INFO_MMAP |
- SNDRV_PCM_INFO_INTERLEAVED |
- SNDRV_PCM_INFO_BLOCK_TRANSFER |
- SNDRV_PCM_INFO_MMAP_VALID),
- .formats = SNDRV_PCM_FMTBIT_S16_LE,
- .rates = SNDRV_PCM_RATE_8000_48000,
- .rate_min = 8000,
- .rate_max = 48000,
- .channels_min = 2,
- .channels_max = 2,
- .buffer_bytes_max = 32768,
- .period_bytes_min = 4096,
- .period_bytes_max = 32768,
- .periods_min = 1,
- .periods_max = 1024,
- };
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- <itemizedlist>
- <listitem><para>
- The <structfield>info</structfield> field contains the type and
- capabilities of this pcm. The bit flags are defined in
- <filename>&lt;sound/asound.h&gt;</filename> as
- <constant>SNDRV_PCM_INFO_XXX</constant>. Here, at least, you
- have to specify whether the mmap is supported and which
- interleaved format is supported.
- When the hardware supports mmap, add the
- <constant>SNDRV_PCM_INFO_MMAP</constant> flag here. When the
- hardware supports the interleaved or the non-interleaved
- formats, <constant>SNDRV_PCM_INFO_INTERLEAVED</constant> or
- <constant>SNDRV_PCM_INFO_NONINTERLEAVED</constant> flag must
- be set, respectively. If both are supported, you can set both,
- too.
- </para>
-
- <para>
- In the above example, <constant>MMAP_VALID</constant> and
- <constant>BLOCK_TRANSFER</constant> are specified for the OSS mmap
- mode. Usually both are set. Of course,
- <constant>MMAP_VALID</constant> is set only if the mmap is
- really supported.
- </para>
-
- <para>
- The other possible flags are
- <constant>SNDRV_PCM_INFO_PAUSE</constant> and
- <constant>SNDRV_PCM_INFO_RESUME</constant>. The
- <constant>PAUSE</constant> bit means that the pcm supports the
- <quote>pause</quote> operation, while the
- <constant>RESUME</constant> bit means that the pcm supports
- the full <quote>suspend/resume</quote> operation.
- If the <constant>PAUSE</constant> flag is set,
- the <structfield>trigger</structfield> callback below
- must handle the corresponding (pause push/release) commands.
- The suspend/resume trigger commands can be defined even without
- the <constant>RESUME</constant> flag. See <link
- linkend="power-management"><citetitle>
- Power Management</citetitle></link> section for details.
- </para>
-
- <para>
- When the PCM substreams can be synchronized (typically,
- synchronized start/stop of a playback and a capture streams),
- you can give <constant>SNDRV_PCM_INFO_SYNC_START</constant>,
- too. In this case, you'll need to check the linked-list of
- PCM substreams in the trigger callback. This will be
- described in the later section.
- </para>
- </listitem>
-
- <listitem>
- <para>
- <structfield>formats</structfield> field contains the bit-flags
- of supported formats (<constant>SNDRV_PCM_FMTBIT_XXX</constant>).
- If the hardware supports more than one format, give all or'ed
- bits. In the example above, the signed 16bit little-endian
- format is specified.
- </para>
- </listitem>
-
- <listitem>
- <para>
- <structfield>rates</structfield> field contains the bit-flags of
- supported rates (<constant>SNDRV_PCM_RATE_XXX</constant>).
- When the chip supports continuous rates, pass
- <constant>CONTINUOUS</constant> bit additionally.
- The pre-defined rate bits are provided only for typical
- rates. If your chip supports unconventional rates, you need to add
- the <constant>KNOT</constant> bit and set up the hardware
- constraint manually (explained later).
- </para>
- </listitem>
-
- <listitem>
- <para>
- <structfield>rate_min</structfield> and
- <structfield>rate_max</structfield> define the minimum and
- maximum sample rate. This should correspond somehow to
- <structfield>rates</structfield> bits.
- </para>
- </listitem>
-
- <listitem>
- <para>
- <structfield>channel_min</structfield> and
- <structfield>channel_max</structfield>
- define, as you might already expected, the minimum and maximum
- number of channels.
- </para>
- </listitem>
-
- <listitem>
- <para>
- <structfield>buffer_bytes_max</structfield> defines the
- maximum buffer size in bytes. There is no
- <structfield>buffer_bytes_min</structfield> field, since
- it can be calculated from the minimum period size and the
- minimum number of periods.
- Meanwhile, <structfield>period_bytes_min</structfield> and
- define the minimum and maximum size of the period in bytes.
- <structfield>periods_max</structfield> and
- <structfield>periods_min</structfield> define the maximum and
- minimum number of periods in the buffer.
- </para>
-
- <para>
- The <quote>period</quote> is a term that corresponds to
- a fragment in the OSS world. The period defines the size at
- which a PCM interrupt is generated. This size strongly
- depends on the hardware.
- Generally, the smaller period size will give you more
- interrupts, that is, more controls.
- In the case of capture, this size defines the input latency.
- On the other hand, the whole buffer size defines the
- output latency for the playback direction.
- </para>
- </listitem>
-
- <listitem>
- <para>
- There is also a field <structfield>fifo_size</structfield>.
- This specifies the size of the hardware FIFO, but currently it
- is neither used in the driver nor in the alsa-lib. So, you
- can ignore this field.
- </para>
- </listitem>
- </itemizedlist>
- </para>
- </section>
-
- <section id="pcm-interface-runtime-config">
- <title>PCM Configurations</title>
- <para>
- Ok, let's go back again to the PCM runtime records.
- The most frequently referred records in the runtime instance are
- the PCM configurations.
- The PCM configurations are stored in the runtime instance
- after the application sends <type>hw_params</type> data via
- alsa-lib. There are many fields copied from hw_params and
- sw_params structs. For example,
- <structfield>format</structfield> holds the format type
- chosen by the application. This field contains the enum value
- <constant>SNDRV_PCM_FORMAT_XXX</constant>.
- </para>
-
- <para>
- One thing to be noted is that the configured buffer and period
- sizes are stored in <quote>frames</quote> in the runtime.
- In the ALSA world, 1 frame = channels * samples-size.
- For conversion between frames and bytes, you can use the
- <function>frames_to_bytes()</function> and
- <function>bytes_to_frames()</function> helper functions.
- <informalexample>
- <programlisting>
-<![CDATA[
- period_bytes = frames_to_bytes(runtime, runtime->period_size);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- Also, many software parameters (sw_params) are
- stored in frames, too. Please check the type of the field.
- <type>snd_pcm_uframes_t</type> is for the frames as unsigned
- integer while <type>snd_pcm_sframes_t</type> is for the frames
- as signed integer.
- </para>
- </section>
-
- <section id="pcm-interface-runtime-dma">
- <title>DMA Buffer Information</title>
- <para>
- The DMA buffer is defined by the following four fields,
- <structfield>dma_area</structfield>,
- <structfield>dma_addr</structfield>,
- <structfield>dma_bytes</structfield> and
- <structfield>dma_private</structfield>.
- The <structfield>dma_area</structfield> holds the buffer
- pointer (the logical address). You can call
- <function>memcpy</function> from/to
- this pointer. Meanwhile, <structfield>dma_addr</structfield>
- holds the physical address of the buffer. This field is
- specified only when the buffer is a linear buffer.
- <structfield>dma_bytes</structfield> holds the size of buffer
- in bytes. <structfield>dma_private</structfield> is used for
- the ALSA DMA allocator.
- </para>
-
- <para>
- If you use a standard ALSA function,
- <function>snd_pcm_lib_malloc_pages()</function>, for
- allocating the buffer, these fields are set by the ALSA middle
- layer, and you should <emphasis>not</emphasis> change them by
- yourself. You can read them but not write them.
- On the other hand, if you want to allocate the buffer by
- yourself, you'll need to manage it in hw_params callback.
- At least, <structfield>dma_bytes</structfield> is mandatory.
- <structfield>dma_area</structfield> is necessary when the
- buffer is mmapped. If your driver doesn't support mmap, this
- field is not necessary. <structfield>dma_addr</structfield>
- is also optional. You can use
- <structfield>dma_private</structfield> as you like, too.
- </para>
- </section>
-
- <section id="pcm-interface-runtime-status">
- <title>Running Status</title>
- <para>
- The running status can be referred via <constant>runtime-&gt;status</constant>.
- This is the pointer to the struct <structname>snd_pcm_mmap_status</structname>
- record. For example, you can get the current DMA hardware
- pointer via <constant>runtime-&gt;status-&gt;hw_ptr</constant>.
- </para>
-
- <para>
- The DMA application pointer can be referred via
- <constant>runtime-&gt;control</constant>, which points to the
- struct <structname>snd_pcm_mmap_control</structname> record.
- However, accessing directly to this value is not recommended.
- </para>
- </section>
-
- <section id="pcm-interface-runtime-private">
- <title>Private Data</title>
- <para>
- You can allocate a record for the substream and store it in
- <constant>runtime-&gt;private_data</constant>. Usually, this
- is done in
- <link linkend="pcm-interface-operators-open-callback"><citetitle>
- the open callback</citetitle></link>.
- Don't mix this with <constant>pcm-&gt;private_data</constant>.
- The <constant>pcm-&gt;private_data</constant> usually points to the
- chip instance assigned statically at the creation of PCM, while the
- <constant>runtime-&gt;private_data</constant> points to a dynamic
- data structure created at the PCM open callback.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_xxx_open(struct snd_pcm_substream *substream)
- {
- struct my_pcm_data *data;
- ....
- data = kmalloc(sizeof(*data), GFP_KERNEL);
- substream->runtime->private_data = data;
- ....
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The allocated object must be released in
- <link linkend="pcm-interface-operators-open-callback"><citetitle>
- the close callback</citetitle></link>.
- </para>
- </section>
-
- </section>
-
- <section id="pcm-interface-operators">
- <title>Operators</title>
- <para>
- OK, now let me give details about each pcm callback
- (<parameter>ops</parameter>). In general, every callback must
- return 0 if successful, or a negative error number
- such as <constant>-EINVAL</constant>. To choose an appropriate
- error number, it is advised to check what value other parts of
- the kernel return when the same kind of request fails.
- </para>
-
- <para>
- The callback function takes at least the argument with
- <structname>snd_pcm_substream</structname> pointer. To retrieve
- the chip record from the given substream instance, you can use the
- following macro.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- int xxx() {
- struct mychip *chip = snd_pcm_substream_chip(substream);
- ....
- }
-]]>
- </programlisting>
- </informalexample>
-
- The macro reads <constant>substream-&gt;private_data</constant>,
- which is a copy of <constant>pcm-&gt;private_data</constant>.
- You can override the former if you need to assign different data
- records per PCM substream. For example, the cmi8330 driver assigns
- different private_data for playback and capture directions,
- because it uses two different codecs (SB- and AD-compatible) for
- different directions.
- </para>
-
- <section id="pcm-interface-operators-open-callback">
- <title>open callback</title>
- <para>
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_xxx_open(struct snd_pcm_substream *substream);
-]]>
- </programlisting>
- </informalexample>
-
- This is called when a pcm substream is opened.
- </para>
-
- <para>
- At least, here you have to initialize the runtime-&gt;hw
- record. Typically, this is done by like this:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_xxx_open(struct snd_pcm_substream *substream)
- {
- struct mychip *chip = snd_pcm_substream_chip(substream);
- struct snd_pcm_runtime *runtime = substream->runtime;
-
- runtime->hw = snd_mychip_playback_hw;
- return 0;
- }
-]]>
- </programlisting>
- </informalexample>
-
- where <parameter>snd_mychip_playback_hw</parameter> is the
- pre-defined hardware description.
- </para>
-
- <para>
- You can allocate a private data in this callback, as described
- in <link linkend="pcm-interface-runtime-private"><citetitle>
- Private Data</citetitle></link> section.
- </para>
-
- <para>
- If the hardware configuration needs more constraints, set the
- hardware constraints here, too.
- See <link linkend="pcm-interface-constraints"><citetitle>
- Constraints</citetitle></link> for more details.
- </para>
- </section>
-
- <section id="pcm-interface-operators-close-callback">
- <title>close callback</title>
- <para>
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_xxx_close(struct snd_pcm_substream *substream);
-]]>
- </programlisting>
- </informalexample>
-
- Obviously, this is called when a pcm substream is closed.
- </para>
-
- <para>
- Any private instance for a pcm substream allocated in the
- open callback will be released here.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_xxx_close(struct snd_pcm_substream *substream)
- {
- ....
- kfree(substream->runtime->private_data);
- ....
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
- </section>
-
- <section id="pcm-interface-operators-ioctl-callback">
- <title>ioctl callback</title>
- <para>
- This is used for any special call to pcm ioctls. But
- usually you can pass a generic ioctl callback,
- <function>snd_pcm_lib_ioctl</function>.
- </para>
- </section>
-
- <section id="pcm-interface-operators-hw-params-callback">
- <title>hw_params callback</title>
- <para>
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_xxx_hw_params(struct snd_pcm_substream *substream,
- struct snd_pcm_hw_params *hw_params);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- This is called when the hardware parameter
- (<structfield>hw_params</structfield>) is set
- up by the application,
- that is, once when the buffer size, the period size, the
- format, etc. are defined for the pcm substream.
- </para>
-
- <para>
- Many hardware setups should be done in this callback,
- including the allocation of buffers.
- </para>
-
- <para>
- Parameters to be initialized are retrieved by
- <function>params_xxx()</function> macros. To allocate
- buffer, you can call a helper function,
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params));
-]]>
- </programlisting>
- </informalexample>
-
- <function>snd_pcm_lib_malloc_pages()</function> is available
- only when the DMA buffers have been pre-allocated.
- See the section <link
- linkend="buffer-and-memory-buffer-types"><citetitle>
- Buffer Types</citetitle></link> for more details.
- </para>
-
- <para>
- Note that this and <structfield>prepare</structfield> callbacks
- may be called multiple times per initialization.
- For example, the OSS emulation may
- call these callbacks at each change via its ioctl.
- </para>
-
- <para>
- Thus, you need to be careful not to allocate the same buffers
- many times, which will lead to memory leaks! Calling the
- helper function above many times is OK. It will release the
- previous buffer automatically when it was already allocated.
- </para>
-
- <para>
- Another note is that this callback is non-atomic
- (schedulable) as default, i.e. when no
- <structfield>nonatomic</structfield> flag set.
- This is important, because the
- <structfield>trigger</structfield> callback
- is atomic (non-schedulable). That is, mutexes or any
- schedule-related functions are not available in
- <structfield>trigger</structfield> callback.
- Please see the subsection
- <link linkend="pcm-interface-atomicity"><citetitle>
- Atomicity</citetitle></link> for details.
- </para>
- </section>
-
- <section id="pcm-interface-operators-hw-free-callback">
- <title>hw_free callback</title>
- <para>
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_xxx_hw_free(struct snd_pcm_substream *substream);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- This is called to release the resources allocated via
- <structfield>hw_params</structfield>. For example, releasing the
- buffer via
- <function>snd_pcm_lib_malloc_pages()</function> is done by
- calling the following:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_pcm_lib_free_pages(substream);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- This function is always called before the close callback is called.
- Also, the callback may be called multiple times, too.
- Keep track whether the resource was already released.
- </para>
- </section>
-
- <section id="pcm-interface-operators-prepare-callback">
- <title>prepare callback</title>
- <para>
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_xxx_prepare(struct snd_pcm_substream *substream);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- This callback is called when the pcm is
- <quote>prepared</quote>. You can set the format type, sample
- rate, etc. here. The difference from
- <structfield>hw_params</structfield> is that the
- <structfield>prepare</structfield> callback will be called each
- time
- <function>snd_pcm_prepare()</function> is called, i.e. when
- recovering after underruns, etc.
- </para>
-
- <para>
- Note that this callback is now non-atomic.
- You can use schedule-related functions safely in this callback.
- </para>
-
- <para>
- In this and the following callbacks, you can refer to the
- values via the runtime record,
- substream-&gt;runtime.
- For example, to get the current
- rate, format or channels, access to
- runtime-&gt;rate,
- runtime-&gt;format or
- runtime-&gt;channels, respectively.
- The physical address of the allocated buffer is set to
- runtime-&gt;dma_area. The buffer and period sizes are
- in runtime-&gt;buffer_size and runtime-&gt;period_size,
- respectively.
- </para>
-
- <para>
- Be careful that this callback will be called many times at
- each setup, too.
- </para>
- </section>
-
- <section id="pcm-interface-operators-trigger-callback">
- <title>trigger callback</title>
- <para>
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_xxx_trigger(struct snd_pcm_substream *substream, int cmd);
-]]>
- </programlisting>
- </informalexample>
-
- This is called when the pcm is started, stopped or paused.
- </para>
-
- <para>
- Which action is specified in the second argument,
- <constant>SNDRV_PCM_TRIGGER_XXX</constant> in
- <filename>&lt;sound/pcm.h&gt;</filename>. At least,
- the <constant>START</constant> and <constant>STOP</constant>
- commands must be defined in this callback.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- switch (cmd) {
- case SNDRV_PCM_TRIGGER_START:
- /* do something to start the PCM engine */
- break;
- case SNDRV_PCM_TRIGGER_STOP:
- /* do something to stop the PCM engine */
- break;
- default:
- return -EINVAL;
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- When the pcm supports the pause operation (given in the info
- field of the hardware table), the <constant>PAUSE_PUSH</constant>
- and <constant>PAUSE_RELEASE</constant> commands must be
- handled here, too. The former is the command to pause the pcm,
- and the latter to restart the pcm again.
- </para>
-
- <para>
- When the pcm supports the suspend/resume operation,
- regardless of full or partial suspend/resume support,
- the <constant>SUSPEND</constant> and <constant>RESUME</constant>
- commands must be handled, too.
- These commands are issued when the power-management status is
- changed. Obviously, the <constant>SUSPEND</constant> and
- <constant>RESUME</constant> commands
- suspend and resume the pcm substream, and usually, they
- are identical to the <constant>STOP</constant> and
- <constant>START</constant> commands, respectively.
- See the <link linkend="power-management"><citetitle>
- Power Management</citetitle></link> section for details.
- </para>
-
- <para>
- As mentioned, this callback is atomic as default unless
- <structfield>nonatomic</structfield> flag set, and
- you cannot call functions which may sleep.
- The trigger callback should be as minimal as possible,
- just really triggering the DMA. The other stuff should be
- initialized hw_params and prepare callbacks properly
- beforehand.
- </para>
- </section>
-
- <section id="pcm-interface-operators-pointer-callback">
- <title>pointer callback</title>
- <para>
- <informalexample>
- <programlisting>
-<![CDATA[
- static snd_pcm_uframes_t snd_xxx_pointer(struct snd_pcm_substream *substream)
-]]>
- </programlisting>
- </informalexample>
-
- This callback is called when the PCM middle layer inquires
- the current hardware position on the buffer. The position must
- be returned in frames,
- ranging from 0 to buffer_size - 1.
- </para>
-
- <para>
- This is called usually from the buffer-update routine in the
- pcm middle layer, which is invoked when
- <function>snd_pcm_period_elapsed()</function> is called in the
- interrupt routine. Then the pcm middle layer updates the
- position and calculates the available space, and wakes up the
- sleeping poll threads, etc.
- </para>
-
- <para>
- This callback is also atomic as default.
- </para>
- </section>
-
- <section id="pcm-interface-operators-copy-silence">
- <title>copy and silence callbacks</title>
- <para>
- These callbacks are not mandatory, and can be omitted in
- most cases. These callbacks are used when the hardware buffer
- cannot be in the normal memory space. Some chips have their
- own buffer on the hardware which is not mappable. In such a
- case, you have to transfer the data manually from the memory
- buffer to the hardware buffer. Or, if the buffer is
- non-contiguous on both physical and virtual memory spaces,
- these callbacks must be defined, too.
- </para>
-
- <para>
- If these two callbacks are defined, copy and set-silence
- operations are done by them. The detailed will be described in
- the later section <link
- linkend="buffer-and-memory"><citetitle>Buffer and Memory
- Management</citetitle></link>.
- </para>
- </section>
-
- <section id="pcm-interface-operators-ack">
- <title>ack callback</title>
- <para>
- This callback is also not mandatory. This callback is called
- when the appl_ptr is updated in read or write operations.
- Some drivers like emu10k1-fx and cs46xx need to track the
- current appl_ptr for the internal buffer, and this callback
- is useful only for such a purpose.
- </para>
- <para>
- This callback is atomic as default.
- </para>
- </section>
-
- <section id="pcm-interface-operators-page-callback">
- <title>page callback</title>
-
- <para>
- This callback is optional too. This callback is used
- mainly for non-contiguous buffers. The mmap calls this
- callback to get the page address. Some examples will be
- explained in the later section <link
- linkend="buffer-and-memory"><citetitle>Buffer and Memory
- Management</citetitle></link>, too.
- </para>
- </section>
- </section>
-
- <section id="pcm-interface-interrupt-handler">
- <title>Interrupt Handler</title>
- <para>
- The rest of pcm stuff is the PCM interrupt handler. The
- role of PCM interrupt handler in the sound driver is to update
- the buffer position and to tell the PCM middle layer when the
- buffer position goes across the prescribed period size. To
- inform this, call the <function>snd_pcm_period_elapsed()</function>
- function.
- </para>
-
- <para>
- There are several types of sound chips to generate the interrupts.
- </para>
-
- <section id="pcm-interface-interrupt-handler-boundary">
- <title>Interrupts at the period (fragment) boundary</title>
- <para>
- This is the most frequently found type: the hardware
- generates an interrupt at each period boundary.
- In this case, you can call
- <function>snd_pcm_period_elapsed()</function> at each
- interrupt.
- </para>
-
- <para>
- <function>snd_pcm_period_elapsed()</function> takes the
- substream pointer as its argument. Thus, you need to keep the
- substream pointer accessible from the chip instance. For
- example, define substream field in the chip record to hold the
- current running substream pointer, and set the pointer value
- at open callback (and reset at close callback).
- </para>
-
- <para>
- If you acquire a spinlock in the interrupt handler, and the
- lock is used in other pcm callbacks, too, then you have to
- release the lock before calling
- <function>snd_pcm_period_elapsed()</function>, because
- <function>snd_pcm_period_elapsed()</function> calls other pcm
- callbacks inside.
- </para>
-
- <para>
- Typical code would be like:
-
- <example>
- <title>Interrupt Handler Case #1</title>
- <programlisting>
-<![CDATA[
- static irqreturn_t snd_mychip_interrupt(int irq, void *dev_id)
- {
- struct mychip *chip = dev_id;
- spin_lock(&chip->lock);
- ....
- if (pcm_irq_invoked(chip)) {
- /* call updater, unlock before it */
- spin_unlock(&chip->lock);
- snd_pcm_period_elapsed(chip->substream);
- spin_lock(&chip->lock);
- /* acknowledge the interrupt if necessary */
- }
- ....
- spin_unlock(&chip->lock);
- return IRQ_HANDLED;
- }
-]]>
- </programlisting>
- </example>
- </para>
- </section>
-
- <section id="pcm-interface-interrupt-handler-timer">
- <title>High frequency timer interrupts</title>
- <para>
- This happens when the hardware doesn't generate interrupts
- at the period boundary but issues timer interrupts at a fixed
- timer rate (e.g. es1968 or ymfpci drivers).
- In this case, you need to check the current hardware
- position and accumulate the processed sample length at each
- interrupt. When the accumulated size exceeds the period
- size, call
- <function>snd_pcm_period_elapsed()</function> and reset the
- accumulator.
- </para>
-
- <para>
- Typical code would be like the following.
-
- <example>
- <title>Interrupt Handler Case #2</title>
- <programlisting>
-<![CDATA[
- static irqreturn_t snd_mychip_interrupt(int irq, void *dev_id)
- {
- struct mychip *chip = dev_id;
- spin_lock(&chip->lock);
- ....
- if (pcm_irq_invoked(chip)) {
- unsigned int last_ptr, size;
- /* get the current hardware pointer (in frames) */
- last_ptr = get_hw_ptr(chip);
- /* calculate the processed frames since the
- * last update
- */
- if (last_ptr < chip->last_ptr)
- size = runtime->buffer_size + last_ptr
- - chip->last_ptr;
- else
- size = last_ptr - chip->last_ptr;
- /* remember the last updated point */
- chip->last_ptr = last_ptr;
- /* accumulate the size */
- chip->size += size;
- /* over the period boundary? */
- if (chip->size >= runtime->period_size) {
- /* reset the accumulator */
- chip->size %= runtime->period_size;
- /* call updater */
- spin_unlock(&chip->lock);
- snd_pcm_period_elapsed(substream);
- spin_lock(&chip->lock);
- }
- /* acknowledge the interrupt if necessary */
- }
- ....
- spin_unlock(&chip->lock);
- return IRQ_HANDLED;
- }
-]]>
- </programlisting>
- </example>
- </para>
- </section>
-
- <section id="pcm-interface-interrupt-handler-both">
- <title>On calling <function>snd_pcm_period_elapsed()</function></title>
- <para>
- In both cases, even if more than one period are elapsed, you
- don't have to call
- <function>snd_pcm_period_elapsed()</function> many times. Call
- only once. And the pcm layer will check the current hardware
- pointer and update to the latest status.
- </para>
- </section>
- </section>
-
- <section id="pcm-interface-atomicity">
- <title>Atomicity</title>
- <para>
- One of the most important (and thus difficult to debug) problems
- in kernel programming are race conditions.
- In the Linux kernel, they are usually avoided via spin-locks, mutexes
- or semaphores. In general, if a race condition can happen
- in an interrupt handler, it has to be managed atomically, and you
- have to use a spinlock to protect the critical session. If the
- critical section is not in interrupt handler code and
- if taking a relatively long time to execute is acceptable, you
- should use mutexes or semaphores instead.
- </para>
-
- <para>
- As already seen, some pcm callbacks are atomic and some are
- not. For example, the <parameter>hw_params</parameter> callback is
- non-atomic, while <parameter>trigger</parameter> callback is
- atomic. This means, the latter is called already in a spinlock
- held by the PCM middle layer. Please take this atomicity into
- account when you choose a locking scheme in the callbacks.
- </para>
-
- <para>
- In the atomic callbacks, you cannot use functions which may call
- <function>schedule</function> or go to
- <function>sleep</function>. Semaphores and mutexes can sleep,
- and hence they cannot be used inside the atomic callbacks
- (e.g. <parameter>trigger</parameter> callback).
- To implement some delay in such a callback, please use
- <function>udelay()</function> or <function>mdelay()</function>.
- </para>
-
- <para>
- All three atomic callbacks (trigger, pointer, and ack) are
- called with local interrupts disabled.
- </para>
-
- <para>
- The recent changes in PCM core code, however, allow all PCM
- operations to be non-atomic. This assumes that the all caller
- sides are in non-atomic contexts. For example, the function
- <function>snd_pcm_period_elapsed()</function> is called
- typically from the interrupt handler. But, if you set up the
- driver to use a threaded interrupt handler, this call can be in
- non-atomic context, too. In such a case, you can set
- <structfield>nonatomic</structfield> filed of
- <structname>snd_pcm</structname> object after creating it.
- When this flag is set, mutex and rwsem are used internally in
- the PCM core instead of spin and rwlocks, so that you can call
- all PCM functions safely in a non-atomic context.
- </para>
-
- </section>
- <section id="pcm-interface-constraints">
- <title>Constraints</title>
- <para>
- If your chip supports unconventional sample rates, or only the
- limited samples, you need to set a constraint for the
- condition.
- </para>
-
- <para>
- For example, in order to restrict the sample rates in the some
- supported values, use
- <function>snd_pcm_hw_constraint_list()</function>.
- You need to call this function in the open callback.
-
- <example>
- <title>Example of Hardware Constraints</title>
- <programlisting>
-<![CDATA[
- static unsigned int rates[] =
- {4000, 10000, 22050, 44100};
- static struct snd_pcm_hw_constraint_list constraints_rates = {
- .count = ARRAY_SIZE(rates),
- .list = rates,
- .mask = 0,
- };
-
- static int snd_mychip_pcm_open(struct snd_pcm_substream *substream)
- {
- int err;
- ....
- err = snd_pcm_hw_constraint_list(substream->runtime, 0,
- SNDRV_PCM_HW_PARAM_RATE,
- &constraints_rates);
- if (err < 0)
- return err;
- ....
- }
-]]>
- </programlisting>
- </example>
- </para>
-
- <para>
- There are many different constraints.
- Look at <filename>sound/pcm.h</filename> for a complete list.
- You can even define your own constraint rules.
- For example, let's suppose my_chip can manage a substream of 1 channel
- if and only if the format is S16_LE, otherwise it supports any format
- specified in the <structname>snd_pcm_hardware</structname> structure (or in any
- other constraint_list). You can build a rule like this:
-
- <example>
- <title>Example of Hardware Constraints for Channels</title>
- <programlisting>
-<![CDATA[
- static int hw_rule_channels_by_format(struct snd_pcm_hw_params *params,
- struct snd_pcm_hw_rule *rule)
- {
- struct snd_interval *c = hw_param_interval(params,
- SNDRV_PCM_HW_PARAM_CHANNELS);
- struct snd_mask *f = hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT);
- struct snd_interval ch;
-
- snd_interval_any(&ch);
- if (f->bits[0] == SNDRV_PCM_FMTBIT_S16_LE) {
- ch.min = ch.max = 1;
- ch.integer = 1;
- return snd_interval_refine(c, &ch);
- }
- return 0;
- }
-]]>
- </programlisting>
- </example>
- </para>
-
- <para>
- Then you need to call this function to add your rule:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_pcm_hw_rule_add(substream->runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
- hw_rule_channels_by_format, NULL,
- SNDRV_PCM_HW_PARAM_FORMAT, -1);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The rule function is called when an application sets the PCM
- format, and it refines the number of channels accordingly.
- But an application may set the number of channels before
- setting the format. Thus you also need to define the inverse rule:
-
- <example>
- <title>Example of Hardware Constraints for Formats</title>
- <programlisting>
-<![CDATA[
- static int hw_rule_format_by_channels(struct snd_pcm_hw_params *params,
- struct snd_pcm_hw_rule *rule)
- {
- struct snd_interval *c = hw_param_interval(params,
- SNDRV_PCM_HW_PARAM_CHANNELS);
- struct snd_mask *f = hw_param_mask(params, SNDRV_PCM_HW_PARAM_FORMAT);
- struct snd_mask fmt;
-
- snd_mask_any(&fmt); /* Init the struct */
- if (c->min < 2) {
- fmt.bits[0] &= SNDRV_PCM_FMTBIT_S16_LE;
- return snd_mask_refine(f, &fmt);
- }
- return 0;
- }
-]]>
- </programlisting>
- </example>
- </para>
-
- <para>
- ...and in the open callback:
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_pcm_hw_rule_add(substream->runtime, 0, SNDRV_PCM_HW_PARAM_FORMAT,
- hw_rule_format_by_channels, NULL,
- SNDRV_PCM_HW_PARAM_CHANNELS, -1);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- I won't give more details here, rather I
- would like to say, <quote>Luke, use the source.</quote>
- </para>
- </section>
-
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- Control Interface -->
-<!-- ****************************************************** -->
- <chapter id="control-interface">
- <title>Control Interface</title>
-
- <section id="control-interface-general">
- <title>General</title>
- <para>
- The control interface is used widely for many switches,
- sliders, etc. which are accessed from user-space. Its most
- important use is the mixer interface. In other words, since ALSA
- 0.9.x, all the mixer stuff is implemented on the control kernel API.
- </para>
-
- <para>
- ALSA has a well-defined AC97 control module. If your chip
- supports only the AC97 and nothing else, you can skip this
- section.
- </para>
-
- <para>
- The control API is defined in
- <filename>&lt;sound/control.h&gt;</filename>.
- Include this file if you want to add your own controls.
- </para>
- </section>
-
- <section id="control-interface-definition">
- <title>Definition of Controls</title>
- <para>
- To create a new control, you need to define the
- following three
- callbacks: <structfield>info</structfield>,
- <structfield>get</structfield> and
- <structfield>put</structfield>. Then, define a
- struct <structname>snd_kcontrol_new</structname> record, such as:
-
- <example>
- <title>Definition of a Control</title>
- <programlisting>
-<![CDATA[
- static struct snd_kcontrol_new my_control = {
- .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
- .name = "PCM Playback Switch",
- .index = 0,
- .access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
- .private_value = 0xffff,
- .info = my_control_info,
- .get = my_control_get,
- .put = my_control_put
- };
-]]>
- </programlisting>
- </example>
- </para>
-
- <para>
- The <structfield>iface</structfield> field specifies the control
- type, <constant>SNDRV_CTL_ELEM_IFACE_XXX</constant>, which
- is usually <constant>MIXER</constant>.
- Use <constant>CARD</constant> for global controls that are not
- logically part of the mixer.
- If the control is closely associated with some specific device on
- the sound card, use <constant>HWDEP</constant>,
- <constant>PCM</constant>, <constant>RAWMIDI</constant>,
- <constant>TIMER</constant>, or <constant>SEQUENCER</constant>, and
- specify the device number with the
- <structfield>device</structfield> and
- <structfield>subdevice</structfield> fields.
- </para>
-
- <para>
- The <structfield>name</structfield> is the name identifier
- string. Since ALSA 0.9.x, the control name is very important,
- because its role is classified from its name. There are
- pre-defined standard control names. The details are described in
- the <link linkend="control-interface-control-names"><citetitle>
- Control Names</citetitle></link> subsection.
- </para>
-
- <para>
- The <structfield>index</structfield> field holds the index number
- of this control. If there are several different controls with
- the same name, they can be distinguished by the index
- number. This is the case when
- several codecs exist on the card. If the index is zero, you can
- omit the definition above.
- </para>
-
- <para>
- The <structfield>access</structfield> field contains the access
- type of this control. Give the combination of bit masks,
- <constant>SNDRV_CTL_ELEM_ACCESS_XXX</constant>, there.
- The details will be explained in
- the <link linkend="control-interface-access-flags"><citetitle>
- Access Flags</citetitle></link> subsection.
- </para>
-
- <para>
- The <structfield>private_value</structfield> field contains
- an arbitrary long integer value for this record. When using
- the generic <structfield>info</structfield>,
- <structfield>get</structfield> and
- <structfield>put</structfield> callbacks, you can pass a value
- through this field. If several small numbers are necessary, you can
- combine them in bitwise. Or, it's possible to give a pointer
- (casted to unsigned long) of some record to this field, too.
- </para>
-
- <para>
- The <structfield>tlv</structfield> field can be used to provide
- metadata about the control; see the
- <link linkend="control-interface-tlv">
- <citetitle>Metadata</citetitle></link> subsection.
- </para>
-
- <para>
- The other three are
- <link linkend="control-interface-callbacks"><citetitle>
- callback functions</citetitle></link>.
- </para>
- </section>
-
- <section id="control-interface-control-names">
- <title>Control Names</title>
- <para>
- There are some standards to define the control names. A
- control is usually defined from the three parts as
- <quote>SOURCE DIRECTION FUNCTION</quote>.
- </para>
-
- <para>
- The first, <constant>SOURCE</constant>, specifies the source
- of the control, and is a string such as <quote>Master</quote>,
- <quote>PCM</quote>, <quote>CD</quote> and
- <quote>Line</quote>. There are many pre-defined sources.
- </para>
-
- <para>
- The second, <constant>DIRECTION</constant>, is one of the
- following strings according to the direction of the control:
- <quote>Playback</quote>, <quote>Capture</quote>, <quote>Bypass
- Playback</quote> and <quote>Bypass Capture</quote>. Or, it can
- be omitted, meaning both playback and capture directions.
- </para>
-
- <para>
- The third, <constant>FUNCTION</constant>, is one of the
- following strings according to the function of the control:
- <quote>Switch</quote>, <quote>Volume</quote> and
- <quote>Route</quote>.
- </para>
-
- <para>
- The example of control names are, thus, <quote>Master Capture
- Switch</quote> or <quote>PCM Playback Volume</quote>.
- </para>
-
- <para>
- There are some exceptions:
- </para>
-
- <section id="control-interface-control-names-global">
- <title>Global capture and playback</title>
- <para>
- <quote>Capture Source</quote>, <quote>Capture Switch</quote>
- and <quote>Capture Volume</quote> are used for the global
- capture (input) source, switch and volume. Similarly,
- <quote>Playback Switch</quote> and <quote>Playback
- Volume</quote> are used for the global output gain switch and
- volume.
- </para>
- </section>
-
- <section id="control-interface-control-names-tone">
- <title>Tone-controls</title>
- <para>
- tone-control switch and volumes are specified like
- <quote>Tone Control - XXX</quote>, e.g. <quote>Tone Control -
- Switch</quote>, <quote>Tone Control - Bass</quote>,
- <quote>Tone Control - Center</quote>.
- </para>
- </section>
-
- <section id="control-interface-control-names-3d">
- <title>3D controls</title>
- <para>
- 3D-control switches and volumes are specified like <quote>3D
- Control - XXX</quote>, e.g. <quote>3D Control -
- Switch</quote>, <quote>3D Control - Center</quote>, <quote>3D
- Control - Space</quote>.
- </para>
- </section>
-
- <section id="control-interface-control-names-mic">
- <title>Mic boost</title>
- <para>
- Mic-boost switch is set as <quote>Mic Boost</quote> or
- <quote>Mic Boost (6dB)</quote>.
- </para>
-
- <para>
- More precise information can be found in
- <filename>Documentation/sound/alsa/ControlNames.txt</filename>.
- </para>
- </section>
- </section>
-
- <section id="control-interface-access-flags">
- <title>Access Flags</title>
-
- <para>
- The access flag is the bitmask which specifies the access type
- of the given control. The default access type is
- <constant>SNDRV_CTL_ELEM_ACCESS_READWRITE</constant>,
- which means both read and write are allowed to this control.
- When the access flag is omitted (i.e. = 0), it is
- considered as <constant>READWRITE</constant> access as default.
- </para>
-
- <para>
- When the control is read-only, pass
- <constant>SNDRV_CTL_ELEM_ACCESS_READ</constant> instead.
- In this case, you don't have to define
- the <structfield>put</structfield> callback.
- Similarly, when the control is write-only (although it's a rare
- case), you can use the <constant>WRITE</constant> flag instead, and
- you don't need the <structfield>get</structfield> callback.
- </para>
-
- <para>
- If the control value changes frequently (e.g. the VU meter),
- <constant>VOLATILE</constant> flag should be given. This means
- that the control may be changed without
- <link linkend="control-interface-change-notification"><citetitle>
- notification</citetitle></link>. Applications should poll such
- a control constantly.
- </para>
-
- <para>
- When the control is inactive, set
- the <constant>INACTIVE</constant> flag, too.
- There are <constant>LOCK</constant> and
- <constant>OWNER</constant> flags to change the write
- permissions.
- </para>
-
- </section>
-
- <section id="control-interface-callbacks">
- <title>Callbacks</title>
-
- <section id="control-interface-callbacks-info">
- <title>info callback</title>
- <para>
- The <structfield>info</structfield> callback is used to get
- detailed information on this control. This must store the
- values of the given struct <structname>snd_ctl_elem_info</structname>
- object. For example, for a boolean control with a single
- element:
-
- <example>
- <title>Example of info callback</title>
- <programlisting>
-<![CDATA[
- static int snd_myctl_mono_info(struct snd_kcontrol *kcontrol,
- struct snd_ctl_elem_info *uinfo)
- {
- uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
- uinfo->count = 1;
- uinfo->value.integer.min = 0;
- uinfo->value.integer.max = 1;
- return 0;
- }
-]]>
- </programlisting>
- </example>
- </para>
-
- <para>
- The <structfield>type</structfield> field specifies the type
- of the control. There are <constant>BOOLEAN</constant>,
- <constant>INTEGER</constant>, <constant>ENUMERATED</constant>,
- <constant>BYTES</constant>, <constant>IEC958</constant> and
- <constant>INTEGER64</constant>. The
- <structfield>count</structfield> field specifies the
- number of elements in this control. For example, a stereo
- volume would have count = 2. The
- <structfield>value</structfield> field is a union, and
- the values stored are depending on the type. The boolean and
- integer types are identical.
- </para>
-
- <para>
- The enumerated type is a bit different from others. You'll
- need to set the string for the currently given item index.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_myctl_enum_info(struct snd_kcontrol *kcontrol,
- struct snd_ctl_elem_info *uinfo)
- {
- static char *texts[4] = {
- "First", "Second", "Third", "Fourth"
- };
- uinfo->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
- uinfo->count = 1;
- uinfo->value.enumerated.items = 4;
- if (uinfo->value.enumerated.item > 3)
- uinfo->value.enumerated.item = 3;
- strcpy(uinfo->value.enumerated.name,
- texts[uinfo->value.enumerated.item]);
- return 0;
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The above callback can be simplified with a helper function,
- <function>snd_ctl_enum_info</function>. The final code
- looks like below.
- (You can pass ARRAY_SIZE(texts) instead of 4 in the third
- argument; it's a matter of taste.)
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_myctl_enum_info(struct snd_kcontrol *kcontrol,
- struct snd_ctl_elem_info *uinfo)
- {
- static char *texts[4] = {
- "First", "Second", "Third", "Fourth"
- };
- return snd_ctl_enum_info(uinfo, 1, 4, texts);
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- Some common info callbacks are available for your convenience:
- <function>snd_ctl_boolean_mono_info()</function> and
- <function>snd_ctl_boolean_stereo_info()</function>.
- Obviously, the former is an info callback for a mono channel
- boolean item, just like <function>snd_myctl_mono_info</function>
- above, and the latter is for a stereo channel boolean item.
- </para>
-
- </section>
-
- <section id="control-interface-callbacks-get">
- <title>get callback</title>
-
- <para>
- This callback is used to read the current value of the
- control and to return to user-space.
- </para>
-
- <para>
- For example,
-
- <example>
- <title>Example of get callback</title>
- <programlisting>
-<![CDATA[
- static int snd_myctl_get(struct snd_kcontrol *kcontrol,
- struct snd_ctl_elem_value *ucontrol)
- {
- struct mychip *chip = snd_kcontrol_chip(kcontrol);
- ucontrol->value.integer.value[0] = get_some_value(chip);
- return 0;
- }
-]]>
- </programlisting>
- </example>
- </para>
-
- <para>
- The <structfield>value</structfield> field depends on
- the type of control as well as on the info callback. For example,
- the sb driver uses this field to store the register offset,
- the bit-shift and the bit-mask. The
- <structfield>private_value</structfield> field is set as follows:
- <informalexample>
- <programlisting>
-<![CDATA[
- .private_value = reg | (shift << 16) | (mask << 24)
-]]>
- </programlisting>
- </informalexample>
- and is retrieved in callbacks like
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_sbmixer_get_single(struct snd_kcontrol *kcontrol,
- struct snd_ctl_elem_value *ucontrol)
- {
- int reg = kcontrol->private_value & 0xff;
- int shift = (kcontrol->private_value >> 16) & 0xff;
- int mask = (kcontrol->private_value >> 24) & 0xff;
- ....
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- In the <structfield>get</structfield> callback,
- you have to fill all the elements if the
- control has more than one elements,
- i.e. <structfield>count</structfield> &gt; 1.
- In the example above, we filled only one element
- (<structfield>value.integer.value[0]</structfield>) since it's
- assumed as <structfield>count</structfield> = 1.
- </para>
- </section>
-
- <section id="control-interface-callbacks-put">
- <title>put callback</title>
-
- <para>
- This callback is used to write a value from user-space.
- </para>
-
- <para>
- For example,
-
- <example>
- <title>Example of put callback</title>
- <programlisting>
-<![CDATA[
- static int snd_myctl_put(struct snd_kcontrol *kcontrol,
- struct snd_ctl_elem_value *ucontrol)
- {
- struct mychip *chip = snd_kcontrol_chip(kcontrol);
- int changed = 0;
- if (chip->current_value !=
- ucontrol->value.integer.value[0]) {
- change_current_value(chip,
- ucontrol->value.integer.value[0]);
- changed = 1;
- }
- return changed;
- }
-]]>
- </programlisting>
- </example>
-
- As seen above, you have to return 1 if the value is
- changed. If the value is not changed, return 0 instead.
- If any fatal error happens, return a negative error code as
- usual.
- </para>
-
- <para>
- As in the <structfield>get</structfield> callback,
- when the control has more than one elements,
- all elements must be evaluated in this callback, too.
- </para>
- </section>
-
- <section id="control-interface-callbacks-all">
- <title>Callbacks are not atomic</title>
- <para>
- All these three callbacks are basically not atomic.
- </para>
- </section>
- </section>
-
- <section id="control-interface-constructor">
- <title>Constructor</title>
- <para>
- When everything is ready, finally we can create a new
- control. To create a control, there are two functions to be
- called, <function>snd_ctl_new1()</function> and
- <function>snd_ctl_add()</function>.
- </para>
-
- <para>
- In the simplest way, you can do like this:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- err = snd_ctl_add(card, snd_ctl_new1(&my_control, chip));
- if (err < 0)
- return err;
-]]>
- </programlisting>
- </informalexample>
-
- where <parameter>my_control</parameter> is the
- struct <structname>snd_kcontrol_new</structname> object defined above, and chip
- is the object pointer to be passed to
- kcontrol-&gt;private_data
- which can be referred to in callbacks.
- </para>
-
- <para>
- <function>snd_ctl_new1()</function> allocates a new
- <structname>snd_kcontrol</structname> instance,
- and <function>snd_ctl_add</function> assigns the given
- control component to the card.
- </para>
- </section>
-
- <section id="control-interface-change-notification">
- <title>Change Notification</title>
- <para>
- If you need to change and update a control in the interrupt
- routine, you can call <function>snd_ctl_notify()</function>. For
- example,
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, id_pointer);
-]]>
- </programlisting>
- </informalexample>
-
- This function takes the card pointer, the event-mask, and the
- control id pointer for the notification. The event-mask
- specifies the types of notification, for example, in the above
- example, the change of control values is notified.
- The id pointer is the pointer of struct <structname>snd_ctl_elem_id</structname>
- to be notified.
- You can find some examples in <filename>es1938.c</filename> or
- <filename>es1968.c</filename> for hardware volume interrupts.
- </para>
- </section>
-
- <section id="control-interface-tlv">
- <title>Metadata</title>
- <para>
- To provide information about the dB values of a mixer control, use
- on of the <constant>DECLARE_TLV_xxx</constant> macros from
- <filename>&lt;sound/tlv.h&gt;</filename> to define a variable
- containing this information, set the<structfield>tlv.p
- </structfield> field to point to this variable, and include the
- <constant>SNDRV_CTL_ELEM_ACCESS_TLV_READ</constant> flag in the
- <structfield>access</structfield> field; like this:
- <informalexample>
- <programlisting>
-<![CDATA[
- static DECLARE_TLV_DB_SCALE(db_scale_my_control, -4050, 150, 0);
-
- static struct snd_kcontrol_new my_control = {
- ...
- .access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
- SNDRV_CTL_ELEM_ACCESS_TLV_READ,
- ...
- .tlv.p = db_scale_my_control,
- };
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The <function>DECLARE_TLV_DB_SCALE</function> macro defines
- information about a mixer control where each step in the control's
- value changes the dB value by a constant dB amount.
- The first parameter is the name of the variable to be defined.
- The second parameter is the minimum value, in units of 0.01 dB.
- The third parameter is the step size, in units of 0.01 dB.
- Set the fourth parameter to 1 if the minimum value actually mutes
- the control.
- </para>
-
- <para>
- The <function>DECLARE_TLV_DB_LINEAR</function> macro defines
- information about a mixer control where the control's value affects
- the output linearly.
- The first parameter is the name of the variable to be defined.
- The second parameter is the minimum value, in units of 0.01 dB.
- The third parameter is the maximum value, in units of 0.01 dB.
- If the minimum value mutes the control, set the second parameter to
- <constant>TLV_DB_GAIN_MUTE</constant>.
- </para>
- </section>
-
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- API for AC97 Codec -->
-<!-- ****************************************************** -->
- <chapter id="api-ac97">
- <title>API for AC97 Codec</title>
-
- <section>
- <title>General</title>
- <para>
- The ALSA AC97 codec layer is a well-defined one, and you don't
- have to write much code to control it. Only low-level control
- routines are necessary. The AC97 codec API is defined in
- <filename>&lt;sound/ac97_codec.h&gt;</filename>.
- </para>
- </section>
-
- <section id="api-ac97-example">
- <title>Full Code Example</title>
- <para>
- <example>
- <title>Example of AC97 Interface</title>
- <programlisting>
-<![CDATA[
- struct mychip {
- ....
- struct snd_ac97 *ac97;
- ....
- };
-
- static unsigned short snd_mychip_ac97_read(struct snd_ac97 *ac97,
- unsigned short reg)
- {
- struct mychip *chip = ac97->private_data;
- ....
- /* read a register value here from the codec */
- return the_register_value;
- }
-
- static void snd_mychip_ac97_write(struct snd_ac97 *ac97,
- unsigned short reg, unsigned short val)
- {
- struct mychip *chip = ac97->private_data;
- ....
- /* write the given register value to the codec */
- }
-
- static int snd_mychip_ac97(struct mychip *chip)
- {
- struct snd_ac97_bus *bus;
- struct snd_ac97_template ac97;
- int err;
- static struct snd_ac97_bus_ops ops = {
- .write = snd_mychip_ac97_write,
- .read = snd_mychip_ac97_read,
- };
-
- err = snd_ac97_bus(chip->card, 0, &ops, NULL, &bus);
- if (err < 0)
- return err;
- memset(&ac97, 0, sizeof(ac97));
- ac97.private_data = chip;
- return snd_ac97_mixer(bus, &ac97, &chip->ac97);
- }
-
-]]>
- </programlisting>
- </example>
- </para>
- </section>
-
- <section id="api-ac97-constructor">
- <title>Constructor</title>
- <para>
- To create an ac97 instance, first call <function>snd_ac97_bus</function>
- with an <type>ac97_bus_ops_t</type> record with callback functions.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_ac97_bus *bus;
- static struct snd_ac97_bus_ops ops = {
- .write = snd_mychip_ac97_write,
- .read = snd_mychip_ac97_read,
- };
-
- snd_ac97_bus(card, 0, &ops, NULL, &pbus);
-]]>
- </programlisting>
- </informalexample>
-
- The bus record is shared among all belonging ac97 instances.
- </para>
-
- <para>
- And then call <function>snd_ac97_mixer()</function> with an
- struct <structname>snd_ac97_template</structname>
- record together with the bus pointer created above.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_ac97_template ac97;
- int err;
-
- memset(&ac97, 0, sizeof(ac97));
- ac97.private_data = chip;
- snd_ac97_mixer(bus, &ac97, &chip->ac97);
-]]>
- </programlisting>
- </informalexample>
-
- where chip-&gt;ac97 is a pointer to a newly created
- <type>ac97_t</type> instance.
- In this case, the chip pointer is set as the private data, so that
- the read/write callback functions can refer to this chip instance.
- This instance is not necessarily stored in the chip
- record. If you need to change the register values from the
- driver, or need the suspend/resume of ac97 codecs, keep this
- pointer to pass to the corresponding functions.
- </para>
- </section>
-
- <section id="api-ac97-callbacks">
- <title>Callbacks</title>
- <para>
- The standard callbacks are <structfield>read</structfield> and
- <structfield>write</structfield>. Obviously they
- correspond to the functions for read and write accesses to the
- hardware low-level codes.
- </para>
-
- <para>
- The <structfield>read</structfield> callback returns the
- register value specified in the argument.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static unsigned short snd_mychip_ac97_read(struct snd_ac97 *ac97,
- unsigned short reg)
- {
- struct mychip *chip = ac97->private_data;
- ....
- return the_register_value;
- }
-]]>
- </programlisting>
- </informalexample>
-
- Here, the chip can be cast from ac97-&gt;private_data.
- </para>
-
- <para>
- Meanwhile, the <structfield>write</structfield> callback is
- used to set the register value.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static void snd_mychip_ac97_write(struct snd_ac97 *ac97,
- unsigned short reg, unsigned short val)
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- These callbacks are non-atomic like the control API callbacks.
- </para>
-
- <para>
- There are also other callbacks:
- <structfield>reset</structfield>,
- <structfield>wait</structfield> and
- <structfield>init</structfield>.
- </para>
-
- <para>
- The <structfield>reset</structfield> callback is used to reset
- the codec. If the chip requires a special kind of reset, you can
- define this callback.
- </para>
-
- <para>
- The <structfield>wait</structfield> callback is used to
- add some waiting time in the standard initialization of the codec. If the
- chip requires the extra waiting time, define this callback.
- </para>
-
- <para>
- The <structfield>init</structfield> callback is used for
- additional initialization of the codec.
- </para>
- </section>
-
- <section id="api-ac97-updating-registers">
- <title>Updating Registers in The Driver</title>
- <para>
- If you need to access to the codec from the driver, you can
- call the following functions:
- <function>snd_ac97_write()</function>,
- <function>snd_ac97_read()</function>,
- <function>snd_ac97_update()</function> and
- <function>snd_ac97_update_bits()</function>.
- </para>
-
- <para>
- Both <function>snd_ac97_write()</function> and
- <function>snd_ac97_update()</function> functions are used to
- set a value to the given register
- (<constant>AC97_XXX</constant>). The difference between them is
- that <function>snd_ac97_update()</function> doesn't write a
- value if the given value has been already set, while
- <function>snd_ac97_write()</function> always rewrites the
- value.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_ac97_write(ac97, AC97_MASTER, 0x8080);
- snd_ac97_update(ac97, AC97_MASTER, 0x8080);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- <function>snd_ac97_read()</function> is used to read the value
- of the given register. For example,
-
- <informalexample>
- <programlisting>
-<![CDATA[
- value = snd_ac97_read(ac97, AC97_MASTER);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- <function>snd_ac97_update_bits()</function> is used to update
- some bits in the given register.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_ac97_update_bits(ac97, reg, mask, value);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- Also, there is a function to change the sample rate (of a
- given register such as
- <constant>AC97_PCM_FRONT_DAC_RATE</constant>) when VRA or
- DRA is supported by the codec:
- <function>snd_ac97_set_rate()</function>.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_ac97_set_rate(ac97, AC97_PCM_FRONT_DAC_RATE, 44100);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The following registers are available to set the rate:
- <constant>AC97_PCM_MIC_ADC_RATE</constant>,
- <constant>AC97_PCM_FRONT_DAC_RATE</constant>,
- <constant>AC97_PCM_LR_ADC_RATE</constant>,
- <constant>AC97_SPDIF</constant>. When
- <constant>AC97_SPDIF</constant> is specified, the register is
- not really changed but the corresponding IEC958 status bits will
- be updated.
- </para>
- </section>
-
- <section id="api-ac97-clock-adjustment">
- <title>Clock Adjustment</title>
- <para>
- In some chips, the clock of the codec isn't 48000 but using a
- PCI clock (to save a quartz!). In this case, change the field
- bus-&gt;clock to the corresponding
- value. For example, intel8x0
- and es1968 drivers have their own function to read from the clock.
- </para>
- </section>
-
- <section id="api-ac97-proc-files">
- <title>Proc Files</title>
- <para>
- The ALSA AC97 interface will create a proc file such as
- <filename>/proc/asound/card0/codec97#0/ac97#0-0</filename> and
- <filename>ac97#0-0+regs</filename>. You can refer to these files to
- see the current status and registers of the codec.
- </para>
- </section>
-
- <section id="api-ac97-multiple-codecs">
- <title>Multiple Codecs</title>
- <para>
- When there are several codecs on the same card, you need to
- call <function>snd_ac97_mixer()</function> multiple times with
- ac97.num=1 or greater. The <structfield>num</structfield> field
- specifies the codec number.
- </para>
-
- <para>
- If you set up multiple codecs, you either need to write
- different callbacks for each codec or check
- ac97-&gt;num in the callback routines.
- </para>
- </section>
-
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- MIDI (MPU401-UART) Interface -->
-<!-- ****************************************************** -->
- <chapter id="midi-interface">
- <title>MIDI (MPU401-UART) Interface</title>
-
- <section id="midi-interface-general">
- <title>General</title>
- <para>
- Many soundcards have built-in MIDI (MPU401-UART)
- interfaces. When the soundcard supports the standard MPU401-UART
- interface, most likely you can use the ALSA MPU401-UART API. The
- MPU401-UART API is defined in
- <filename>&lt;sound/mpu401.h&gt;</filename>.
- </para>
-
- <para>
- Some soundchips have a similar but slightly different
- implementation of mpu401 stuff. For example, emu10k1 has its own
- mpu401 routines.
- </para>
- </section>
-
- <section id="midi-interface-constructor">
- <title>Constructor</title>
- <para>
- To create a rawmidi object, call
- <function>snd_mpu401_uart_new()</function>.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_rawmidi *rmidi;
- snd_mpu401_uart_new(card, 0, MPU401_HW_MPU401, port, info_flags,
- irq, &rmidi);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The first argument is the card pointer, and the second is the
- index of this component. You can create up to 8 rawmidi
- devices.
- </para>
-
- <para>
- The third argument is the type of the hardware,
- <constant>MPU401_HW_XXX</constant>. If it's not a special one,
- you can use <constant>MPU401_HW_MPU401</constant>.
- </para>
-
- <para>
- The 4th argument is the I/O port address. Many
- backward-compatible MPU401 have an I/O port such as 0x330. Or, it
- might be a part of its own PCI I/O region. It depends on the
- chip design.
- </para>
-
- <para>
- The 5th argument is a bitflag for additional information.
- When the I/O port address above is part of the PCI I/O
- region, the MPU401 I/O port might have been already allocated
- (reserved) by the driver itself. In such a case, pass a bit flag
- <constant>MPU401_INFO_INTEGRATED</constant>,
- and the mpu401-uart layer will allocate the I/O ports by itself.
- </para>
-
- <para>
- When the controller supports only the input or output MIDI stream,
- pass the <constant>MPU401_INFO_INPUT</constant> or
- <constant>MPU401_INFO_OUTPUT</constant> bitflag, respectively.
- Then the rawmidi instance is created as a single stream.
- </para>
-
- <para>
- <constant>MPU401_INFO_MMIO</constant> bitflag is used to change
- the access method to MMIO (via readb and writeb) instead of
- iob and outb. In this case, you have to pass the iomapped address
- to <function>snd_mpu401_uart_new()</function>.
- </para>
-
- <para>
- When <constant>MPU401_INFO_TX_IRQ</constant> is set, the output
- stream isn't checked in the default interrupt handler. The driver
- needs to call <function>snd_mpu401_uart_interrupt_tx()</function>
- by itself to start processing the output stream in the irq handler.
- </para>
-
- <para>
- If the MPU-401 interface shares its interrupt with the other logical
- devices on the card, set <constant>MPU401_INFO_IRQ_HOOK</constant>
- (see <link linkend="midi-interface-interrupt-handler"><citetitle>
- below</citetitle></link>).
- </para>
-
- <para>
- Usually, the port address corresponds to the command port and
- port + 1 corresponds to the data port. If not, you may change
- the <structfield>cport</structfield> field of
- struct <structname>snd_mpu401</structname> manually
- afterward. However, <structname>snd_mpu401</structname> pointer is not
- returned explicitly by
- <function>snd_mpu401_uart_new()</function>. You need to cast
- rmidi-&gt;private_data to
- <structname>snd_mpu401</structname> explicitly,
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_mpu401 *mpu;
- mpu = rmidi->private_data;
-]]>
- </programlisting>
- </informalexample>
-
- and reset the cport as you like:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- mpu->cport = my_own_control_port;
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The 6th argument specifies the ISA irq number that will be
- allocated. If no interrupt is to be allocated (because your
- code is already allocating a shared interrupt, or because the
- device does not use interrupts), pass -1 instead.
- For a MPU-401 device without an interrupt, a polling timer
- will be used instead.
- </para>
- </section>
-
- <section id="midi-interface-interrupt-handler">
- <title>Interrupt Handler</title>
- <para>
- When the interrupt is allocated in
- <function>snd_mpu401_uart_new()</function>, an exclusive ISA
- interrupt handler is automatically used, hence you don't have
- anything else to do than creating the mpu401 stuff. Otherwise, you
- have to set <constant>MPU401_INFO_IRQ_HOOK</constant>, and call
- <function>snd_mpu401_uart_interrupt()</function> explicitly from your
- own interrupt handler when it has determined that a UART interrupt
- has occurred.
- </para>
-
- <para>
- In this case, you need to pass the private_data of the
- returned rawmidi object from
- <function>snd_mpu401_uart_new()</function> as the second
- argument of <function>snd_mpu401_uart_interrupt()</function>.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_mpu401_uart_interrupt(irq, rmidi->private_data, regs);
-]]>
- </programlisting>
- </informalexample>
- </para>
- </section>
-
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- RawMIDI Interface -->
-<!-- ****************************************************** -->
- <chapter id="rawmidi-interface">
- <title>RawMIDI Interface</title>
-
- <section id="rawmidi-interface-overview">
- <title>Overview</title>
-
- <para>
- The raw MIDI interface is used for hardware MIDI ports that can
- be accessed as a byte stream. It is not used for synthesizer
- chips that do not directly understand MIDI.
- </para>
-
- <para>
- ALSA handles file and buffer management. All you have to do is
- to write some code to move data between the buffer and the
- hardware.
- </para>
-
- <para>
- The rawmidi API is defined in
- <filename>&lt;sound/rawmidi.h&gt;</filename>.
- </para>
- </section>
-
- <section id="rawmidi-interface-constructor">
- <title>Constructor</title>
-
- <para>
- To create a rawmidi device, call the
- <function>snd_rawmidi_new</function> function:
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_rawmidi *rmidi;
- err = snd_rawmidi_new(chip->card, "MyMIDI", 0, outs, ins, &rmidi);
- if (err < 0)
- return err;
- rmidi->private_data = chip;
- strcpy(rmidi->name, "My MIDI");
- rmidi->info_flags = SNDRV_RAWMIDI_INFO_OUTPUT |
- SNDRV_RAWMIDI_INFO_INPUT |
- SNDRV_RAWMIDI_INFO_DUPLEX;
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The first argument is the card pointer, the second argument is
- the ID string.
- </para>
-
- <para>
- The third argument is the index of this component. You can
- create up to 8 rawmidi devices.
- </para>
-
- <para>
- The fourth and fifth arguments are the number of output and
- input substreams, respectively, of this device (a substream is
- the equivalent of a MIDI port).
- </para>
-
- <para>
- Set the <structfield>info_flags</structfield> field to specify
- the capabilities of the device.
- Set <constant>SNDRV_RAWMIDI_INFO_OUTPUT</constant> if there is
- at least one output port,
- <constant>SNDRV_RAWMIDI_INFO_INPUT</constant> if there is at
- least one input port,
- and <constant>SNDRV_RAWMIDI_INFO_DUPLEX</constant> if the device
- can handle output and input at the same time.
- </para>
-
- <para>
- After the rawmidi device is created, you need to set the
- operators (callbacks) for each substream. There are helper
- functions to set the operators for all the substreams of a device:
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &snd_mymidi_output_ops);
- snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT, &snd_mymidi_input_ops);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The operators are usually defined like this:
- <informalexample>
- <programlisting>
-<![CDATA[
- static struct snd_rawmidi_ops snd_mymidi_output_ops = {
- .open = snd_mymidi_output_open,
- .close = snd_mymidi_output_close,
- .trigger = snd_mymidi_output_trigger,
- };
-]]>
- </programlisting>
- </informalexample>
- These callbacks are explained in the <link
- linkend="rawmidi-interface-callbacks"><citetitle>Callbacks</citetitle></link>
- section.
- </para>
-
- <para>
- If there are more than one substream, you should give a
- unique name to each of them:
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_rawmidi_substream *substream;
- list_for_each_entry(substream,
- &rmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT].substreams,
- list {
- sprintf(substream->name, "My MIDI Port %d", substream->number + 1);
- }
- /* same for SNDRV_RAWMIDI_STREAM_INPUT */
-]]>
- </programlisting>
- </informalexample>
- </para>
- </section>
-
- <section id="rawmidi-interface-callbacks">
- <title>Callbacks</title>
-
- <para>
- In all the callbacks, the private data that you've set for the
- rawmidi device can be accessed as
- substream-&gt;rmidi-&gt;private_data.
- <!-- <code> isn't available before DocBook 4.3 -->
- </para>
-
- <para>
- If there is more than one port, your callbacks can determine the
- port index from the struct snd_rawmidi_substream data passed to each
- callback:
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_rawmidi_substream *substream;
- int index = substream->number;
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <section id="rawmidi-interface-op-open">
- <title><function>open</function> callback</title>
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_xxx_open(struct snd_rawmidi_substream *substream);
-]]>
- </programlisting>
- </informalexample>
-
- <para>
- This is called when a substream is opened.
- You can initialize the hardware here, but you shouldn't
- start transmitting/receiving data yet.
- </para>
- </section>
-
- <section id="rawmidi-interface-op-close">
- <title><function>close</function> callback</title>
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_xxx_close(struct snd_rawmidi_substream *substream);
-]]>
- </programlisting>
- </informalexample>
-
- <para>
- Guess what.
- </para>
-
- <para>
- The <function>open</function> and <function>close</function>
- callbacks of a rawmidi device are serialized with a mutex,
- and can sleep.
- </para>
- </section>
-
- <section id="rawmidi-interface-op-trigger-out">
- <title><function>trigger</function> callback for output
- substreams</title>
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static void snd_xxx_output_trigger(struct snd_rawmidi_substream *substream, int up);
-]]>
- </programlisting>
- </informalexample>
-
- <para>
- This is called with a nonzero <parameter>up</parameter>
- parameter when there is some data in the substream buffer that
- must be transmitted.
- </para>
-
- <para>
- To read data from the buffer, call
- <function>snd_rawmidi_transmit_peek</function>. It will
- return the number of bytes that have been read; this will be
- less than the number of bytes requested when there are no more
- data in the buffer.
- After the data have been transmitted successfully, call
- <function>snd_rawmidi_transmit_ack</function> to remove the
- data from the substream buffer:
- <informalexample>
- <programlisting>
-<![CDATA[
- unsigned char data;
- while (snd_rawmidi_transmit_peek(substream, &data, 1) == 1) {
- if (snd_mychip_try_to_transmit(data))
- snd_rawmidi_transmit_ack(substream, 1);
- else
- break; /* hardware FIFO full */
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- If you know beforehand that the hardware will accept data, you
- can use the <function>snd_rawmidi_transmit</function> function
- which reads some data and removes them from the buffer at once:
- <informalexample>
- <programlisting>
-<![CDATA[
- while (snd_mychip_transmit_possible()) {
- unsigned char data;
- if (snd_rawmidi_transmit(substream, &data, 1) != 1)
- break; /* no more data */
- snd_mychip_transmit(data);
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- If you know beforehand how many bytes you can accept, you can
- use a buffer size greater than one with the
- <function>snd_rawmidi_transmit*</function> functions.
- </para>
-
- <para>
- The <function>trigger</function> callback must not sleep. If
- the hardware FIFO is full before the substream buffer has been
- emptied, you have to continue transmitting data later, either
- in an interrupt handler, or with a timer if the hardware
- doesn't have a MIDI transmit interrupt.
- </para>
-
- <para>
- The <function>trigger</function> callback is called with a
- zero <parameter>up</parameter> parameter when the transmission
- of data should be aborted.
- </para>
- </section>
-
- <section id="rawmidi-interface-op-trigger-in">
- <title><function>trigger</function> callback for input
- substreams</title>
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static void snd_xxx_input_trigger(struct snd_rawmidi_substream *substream, int up);
-]]>
- </programlisting>
- </informalexample>
-
- <para>
- This is called with a nonzero <parameter>up</parameter>
- parameter to enable receiving data, or with a zero
- <parameter>up</parameter> parameter do disable receiving data.
- </para>
-
- <para>
- The <function>trigger</function> callback must not sleep; the
- actual reading of data from the device is usually done in an
- interrupt handler.
- </para>
-
- <para>
- When data reception is enabled, your interrupt handler should
- call <function>snd_rawmidi_receive</function> for all received
- data:
- <informalexample>
- <programlisting>
-<![CDATA[
- void snd_mychip_midi_interrupt(...)
- {
- while (mychip_midi_available()) {
- unsigned char data;
- data = mychip_midi_read();
- snd_rawmidi_receive(substream, &data, 1);
- }
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
- </section>
-
- <section id="rawmidi-interface-op-drain">
- <title><function>drain</function> callback</title>
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static void snd_xxx_drain(struct snd_rawmidi_substream *substream);
-]]>
- </programlisting>
- </informalexample>
-
- <para>
- This is only used with output substreams. This function should wait
- until all data read from the substream buffer have been transmitted.
- This ensures that the device can be closed and the driver unloaded
- without losing data.
- </para>
-
- <para>
- This callback is optional. If you do not set
- <structfield>drain</structfield> in the struct snd_rawmidi_ops
- structure, ALSA will simply wait for 50&nbsp;milliseconds
- instead.
- </para>
- </section>
- </section>
-
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- Miscellaneous Devices -->
-<!-- ****************************************************** -->
- <chapter id="misc-devices">
- <title>Miscellaneous Devices</title>
-
- <section id="misc-devices-opl3">
- <title>FM OPL3</title>
- <para>
- The FM OPL3 is still used in many chips (mainly for backward
- compatibility). ALSA has a nice OPL3 FM control layer, too. The
- OPL3 API is defined in
- <filename>&lt;sound/opl3.h&gt;</filename>.
- </para>
-
- <para>
- FM registers can be directly accessed through the direct-FM API,
- defined in <filename>&lt;sound/asound_fm.h&gt;</filename>. In
- ALSA native mode, FM registers are accessed through
- the Hardware-Dependent Device direct-FM extension API, whereas in
- OSS compatible mode, FM registers can be accessed with the OSS
- direct-FM compatible API in <filename>/dev/dmfmX</filename> device.
- </para>
-
- <para>
- To create the OPL3 component, you have two functions to
- call. The first one is a constructor for the <type>opl3_t</type>
- instance.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_opl3 *opl3;
- snd_opl3_create(card, lport, rport, OPL3_HW_OPL3_XXX,
- integrated, &opl3);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The first argument is the card pointer, the second one is the
- left port address, and the third is the right port address. In
- most cases, the right port is placed at the left port + 2.
- </para>
-
- <para>
- The fourth argument is the hardware type.
- </para>
-
- <para>
- When the left and right ports have been already allocated by
- the card driver, pass non-zero to the fifth argument
- (<parameter>integrated</parameter>). Otherwise, the opl3 module will
- allocate the specified ports by itself.
- </para>
-
- <para>
- When the accessing the hardware requires special method
- instead of the standard I/O access, you can create opl3 instance
- separately with <function>snd_opl3_new()</function>.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_opl3 *opl3;
- snd_opl3_new(card, OPL3_HW_OPL3_XXX, &opl3);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- Then set <structfield>command</structfield>,
- <structfield>private_data</structfield> and
- <structfield>private_free</structfield> for the private
- access function, the private data and the destructor.
- The l_port and r_port are not necessarily set. Only the
- command must be set properly. You can retrieve the data
- from the opl3-&gt;private_data field.
- </para>
-
- <para>
- After creating the opl3 instance via <function>snd_opl3_new()</function>,
- call <function>snd_opl3_init()</function> to initialize the chip to the
- proper state. Note that <function>snd_opl3_create()</function> always
- calls it internally.
- </para>
-
- <para>
- If the opl3 instance is created successfully, then create a
- hwdep device for this opl3.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_hwdep *opl3hwdep;
- snd_opl3_hwdep_new(opl3, 0, 1, &opl3hwdep);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The first argument is the <type>opl3_t</type> instance you
- created, and the second is the index number, usually 0.
- </para>
-
- <para>
- The third argument is the index-offset for the sequencer
- client assigned to the OPL3 port. When there is an MPU401-UART,
- give 1 for here (UART always takes 0).
- </para>
- </section>
-
- <section id="misc-devices-hardware-dependent">
- <title>Hardware-Dependent Devices</title>
- <para>
- Some chips need user-space access for special
- controls or for loading the micro code. In such a case, you can
- create a hwdep (hardware-dependent) device. The hwdep API is
- defined in <filename>&lt;sound/hwdep.h&gt;</filename>. You can
- find examples in opl3 driver or
- <filename>isa/sb/sb16_csp.c</filename>.
- </para>
-
- <para>
- The creation of the <type>hwdep</type> instance is done via
- <function>snd_hwdep_new()</function>.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_hwdep *hw;
- snd_hwdep_new(card, "My HWDEP", 0, &hw);
-]]>
- </programlisting>
- </informalexample>
-
- where the third argument is the index number.
- </para>
-
- <para>
- You can then pass any pointer value to the
- <parameter>private_data</parameter>.
- If you assign a private data, you should define the
- destructor, too. The destructor function is set in
- the <structfield>private_free</structfield> field.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct mydata *p = kmalloc(sizeof(*p), GFP_KERNEL);
- hw->private_data = p;
- hw->private_free = mydata_free;
-]]>
- </programlisting>
- </informalexample>
-
- and the implementation of the destructor would be:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static void mydata_free(struct snd_hwdep *hw)
- {
- struct mydata *p = hw->private_data;
- kfree(p);
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The arbitrary file operations can be defined for this
- instance. The file operators are defined in
- the <parameter>ops</parameter> table. For example, assume that
- this chip needs an ioctl.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- hw->ops.open = mydata_open;
- hw->ops.ioctl = mydata_ioctl;
- hw->ops.release = mydata_release;
-]]>
- </programlisting>
- </informalexample>
-
- And implement the callback functions as you like.
- </para>
- </section>
-
- <section id="misc-devices-IEC958">
- <title>IEC958 (S/PDIF)</title>
- <para>
- Usually the controls for IEC958 devices are implemented via
- the control interface. There is a macro to compose a name string for
- IEC958 controls, <function>SNDRV_CTL_NAME_IEC958()</function>
- defined in <filename>&lt;include/asound.h&gt;</filename>.
- </para>
-
- <para>
- There are some standard controls for IEC958 status bits. These
- controls use the type <type>SNDRV_CTL_ELEM_TYPE_IEC958</type>,
- and the size of element is fixed as 4 bytes array
- (value.iec958.status[x]). For the <structfield>info</structfield>
- callback, you don't specify
- the value field for this type (the count field must be set,
- though).
- </para>
-
- <para>
- <quote>IEC958 Playback Con Mask</quote> is used to return the
- bit-mask for the IEC958 status bits of consumer mode. Similarly,
- <quote>IEC958 Playback Pro Mask</quote> returns the bitmask for
- professional mode. They are read-only controls, and are defined
- as MIXER controls (iface =
- <constant>SNDRV_CTL_ELEM_IFACE_MIXER</constant>).
- </para>
-
- <para>
- Meanwhile, <quote>IEC958 Playback Default</quote> control is
- defined for getting and setting the current default IEC958
- bits. Note that this one is usually defined as a PCM control
- (iface = <constant>SNDRV_CTL_ELEM_IFACE_PCM</constant>),
- although in some places it's defined as a MIXER control.
- </para>
-
- <para>
- In addition, you can define the control switches to
- enable/disable or to set the raw bit mode. The implementation
- will depend on the chip, but the control should be named as
- <quote>IEC958 xxx</quote>, preferably using
- the <function>SNDRV_CTL_NAME_IEC958()</function> macro.
- </para>
-
- <para>
- You can find several cases, for example,
- <filename>pci/emu10k1</filename>,
- <filename>pci/ice1712</filename>, or
- <filename>pci/cmipci.c</filename>.
- </para>
- </section>
-
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- Buffer and Memory Management -->
-<!-- ****************************************************** -->
- <chapter id="buffer-and-memory">
- <title>Buffer and Memory Management</title>
-
- <section id="buffer-and-memory-buffer-types">
- <title>Buffer Types</title>
- <para>
- ALSA provides several different buffer allocation functions
- depending on the bus and the architecture. All these have a
- consistent API. The allocation of physically-contiguous pages is
- done via
- <function>snd_malloc_xxx_pages()</function> function, where xxx
- is the bus type.
- </para>
-
- <para>
- The allocation of pages with fallback is
- <function>snd_malloc_xxx_pages_fallback()</function>. This
- function tries to allocate the specified pages but if the pages
- are not available, it tries to reduce the page sizes until
- enough space is found.
- </para>
-
- <para>
- The release the pages, call
- <function>snd_free_xxx_pages()</function> function.
- </para>
-
- <para>
- Usually, ALSA drivers try to allocate and reserve
- a large contiguous physical space
- at the time the module is loaded for the later use.
- This is called <quote>pre-allocation</quote>.
- As already written, you can call the following function at
- pcm instance construction time (in the case of PCI bus).
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV,
- snd_dma_pci_data(pci), size, max);
-]]>
- </programlisting>
- </informalexample>
-
- where <parameter>size</parameter> is the byte size to be
- pre-allocated and the <parameter>max</parameter> is the maximum
- size to be changed via the <filename>prealloc</filename> proc file.
- The allocator will try to get an area as large as possible
- within the given size.
- </para>
-
- <para>
- The second argument (type) and the third argument (device pointer)
- are dependent on the bus.
- In the case of the ISA bus, pass <function>snd_dma_isa_data()</function>
- as the third argument with <constant>SNDRV_DMA_TYPE_DEV</constant> type.
- For the continuous buffer unrelated to the bus can be pre-allocated
- with <constant>SNDRV_DMA_TYPE_CONTINUOUS</constant> type and the
- <function>snd_dma_continuous_data(GFP_KERNEL)</function> device pointer,
- where <constant>GFP_KERNEL</constant> is the kernel allocation flag to
- use.
- For the PCI scatter-gather buffers, use
- <constant>SNDRV_DMA_TYPE_DEV_SG</constant> with
- <function>snd_dma_pci_data(pci)</function>
- (see the
- <link linkend="buffer-and-memory-non-contiguous"><citetitle>Non-Contiguous Buffers
- </citetitle></link> section).
- </para>
-
- <para>
- Once the buffer is pre-allocated, you can use the
- allocator in the <structfield>hw_params</structfield> callback:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_pcm_lib_malloc_pages(substream, size);
-]]>
- </programlisting>
- </informalexample>
-
- Note that you have to pre-allocate to use this function.
- </para>
- </section>
-
- <section id="buffer-and-memory-external-hardware">
- <title>External Hardware Buffers</title>
- <para>
- Some chips have their own hardware buffers and the DMA
- transfer from the host memory is not available. In such a case,
- you need to either 1) copy/set the audio data directly to the
- external hardware buffer, or 2) make an intermediate buffer and
- copy/set the data from it to the external hardware buffer in
- interrupts (or in tasklets, preferably).
- </para>
-
- <para>
- The first case works fine if the external hardware buffer is large
- enough. This method doesn't need any extra buffers and thus is
- more effective. You need to define the
- <structfield>copy</structfield> and
- <structfield>silence</structfield> callbacks for
- the data transfer. However, there is a drawback: it cannot
- be mmapped. The examples are GUS's GF1 PCM or emu8000's
- wavetable PCM.
- </para>
-
- <para>
- The second case allows for mmap on the buffer, although you have
- to handle an interrupt or a tasklet to transfer the data
- from the intermediate buffer to the hardware buffer. You can find an
- example in the vxpocket driver.
- </para>
-
- <para>
- Another case is when the chip uses a PCI memory-map
- region for the buffer instead of the host memory. In this case,
- mmap is available only on certain architectures like the Intel one.
- In non-mmap mode, the data cannot be transferred as in the normal
- way. Thus you need to define the <structfield>copy</structfield> and
- <structfield>silence</structfield> callbacks as well,
- as in the cases above. The examples are found in
- <filename>rme32.c</filename> and <filename>rme96.c</filename>.
- </para>
-
- <para>
- The implementation of the <structfield>copy</structfield> and
- <structfield>silence</structfield> callbacks depends upon
- whether the hardware supports interleaved or non-interleaved
- samples. The <structfield>copy</structfield> callback is
- defined like below, a bit
- differently depending whether the direction is playback or
- capture:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int playback_copy(struct snd_pcm_substream *substream, int channel,
- snd_pcm_uframes_t pos, void *src, snd_pcm_uframes_t count);
- static int capture_copy(struct snd_pcm_substream *substream, int channel,
- snd_pcm_uframes_t pos, void *dst, snd_pcm_uframes_t count);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- In the case of interleaved samples, the second argument
- (<parameter>channel</parameter>) is not used. The third argument
- (<parameter>pos</parameter>) points the
- current position offset in frames.
- </para>
-
- <para>
- The meaning of the fourth argument is different between
- playback and capture. For playback, it holds the source data
- pointer, and for capture, it's the destination data pointer.
- </para>
-
- <para>
- The last argument is the number of frames to be copied.
- </para>
-
- <para>
- What you have to do in this callback is again different
- between playback and capture directions. In the
- playback case, you copy the given amount of data
- (<parameter>count</parameter>) at the specified pointer
- (<parameter>src</parameter>) to the specified offset
- (<parameter>pos</parameter>) on the hardware buffer. When
- coded like memcpy-like way, the copy would be like:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- my_memcpy(my_buffer + frames_to_bytes(runtime, pos), src,
- frames_to_bytes(runtime, count));
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- For the capture direction, you copy the given amount of
- data (<parameter>count</parameter>) at the specified offset
- (<parameter>pos</parameter>) on the hardware buffer to the
- specified pointer (<parameter>dst</parameter>).
-
- <informalexample>
- <programlisting>
-<![CDATA[
- my_memcpy(dst, my_buffer + frames_to_bytes(runtime, pos),
- frames_to_bytes(runtime, count));
-]]>
- </programlisting>
- </informalexample>
-
- Note that both the position and the amount of data are given
- in frames.
- </para>
-
- <para>
- In the case of non-interleaved samples, the implementation
- will be a bit more complicated.
- </para>
-
- <para>
- You need to check the channel argument, and if it's -1, copy
- the whole channels. Otherwise, you have to copy only the
- specified channel. Please check
- <filename>isa/gus/gus_pcm.c</filename> as an example.
- </para>
-
- <para>
- The <structfield>silence</structfield> callback is also
- implemented in a similar way.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int silence(struct snd_pcm_substream *substream, int channel,
- snd_pcm_uframes_t pos, snd_pcm_uframes_t count);
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The meanings of arguments are the same as in the
- <structfield>copy</structfield>
- callback, although there is no <parameter>src/dst</parameter>
- argument. In the case of interleaved samples, the channel
- argument has no meaning, as well as on
- <structfield>copy</structfield> callback.
- </para>
-
- <para>
- The role of <structfield>silence</structfield> callback is to
- set the given amount
- (<parameter>count</parameter>) of silence data at the
- specified offset (<parameter>pos</parameter>) on the hardware
- buffer. Suppose that the data format is signed (that is, the
- silent-data is 0), and the implementation using a memset-like
- function would be like:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- my_memcpy(my_buffer + frames_to_bytes(runtime, pos), 0,
- frames_to_bytes(runtime, count));
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- In the case of non-interleaved samples, again, the
- implementation becomes a bit more complicated. See, for example,
- <filename>isa/gus/gus_pcm.c</filename>.
- </para>
- </section>
-
- <section id="buffer-and-memory-non-contiguous">
- <title>Non-Contiguous Buffers</title>
- <para>
- If your hardware supports the page table as in emu10k1 or the
- buffer descriptors as in via82xx, you can use the scatter-gather
- (SG) DMA. ALSA provides an interface for handling SG-buffers.
- The API is provided in <filename>&lt;sound/pcm.h&gt;</filename>.
- </para>
-
- <para>
- For creating the SG-buffer handler, call
- <function>snd_pcm_lib_preallocate_pages()</function> or
- <function>snd_pcm_lib_preallocate_pages_for_all()</function>
- with <constant>SNDRV_DMA_TYPE_DEV_SG</constant>
- in the PCM constructor like other PCI pre-allocator.
- You need to pass <function>snd_dma_pci_data(pci)</function>,
- where pci is the struct <structname>pci_dev</structname> pointer
- of the chip as well.
- The <type>struct snd_sg_buf</type> instance is created as
- substream-&gt;dma_private. You can cast
- the pointer like:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_sg_buf *sgbuf = (struct snd_sg_buf *)substream->dma_private;
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- Then call <function>snd_pcm_lib_malloc_pages()</function>
- in the <structfield>hw_params</structfield> callback
- as well as in the case of normal PCI buffer.
- The SG-buffer handler will allocate the non-contiguous kernel
- pages of the given size and map them onto the virtually contiguous
- memory. The virtual pointer is addressed in runtime-&gt;dma_area.
- The physical address (runtime-&gt;dma_addr) is set to zero,
- because the buffer is physically non-contiguous.
- The physical address table is set up in sgbuf-&gt;table.
- You can get the physical address at a certain offset via
- <function>snd_pcm_sgbuf_get_addr()</function>.
- </para>
-
- <para>
- When a SG-handler is used, you need to set
- <function>snd_pcm_sgbuf_ops_page</function> as
- the <structfield>page</structfield> callback.
- (See <link linkend="pcm-interface-operators-page-callback">
- <citetitle>page callback section</citetitle></link>.)
- </para>
-
- <para>
- To release the data, call
- <function>snd_pcm_lib_free_pages()</function> in the
- <structfield>hw_free</structfield> callback as usual.
- </para>
- </section>
-
- <section id="buffer-and-memory-vmalloced">
- <title>Vmalloc'ed Buffers</title>
- <para>
- It's possible to use a buffer allocated via
- <function>vmalloc</function>, for example, for an intermediate
- buffer. Since the allocated pages are not contiguous, you need
- to set the <structfield>page</structfield> callback to obtain
- the physical address at every offset.
- </para>
-
- <para>
- The implementation of <structfield>page</structfield> callback
- would be like this:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- #include <linux/vmalloc.h>
-
- /* get the physical page pointer on the given offset */
- static struct page *mychip_page(struct snd_pcm_substream *substream,
- unsigned long offset)
- {
- void *pageptr = substream->runtime->dma_area + offset;
- return vmalloc_to_page(pageptr);
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
- </section>
-
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- Proc Interface -->
-<!-- ****************************************************** -->
- <chapter id="proc-interface">
- <title>Proc Interface</title>
- <para>
- ALSA provides an easy interface for procfs. The proc files are
- very useful for debugging. I recommend you set up proc files if
- you write a driver and want to get a running status or register
- dumps. The API is found in
- <filename>&lt;sound/info.h&gt;</filename>.
- </para>
-
- <para>
- To create a proc file, call
- <function>snd_card_proc_new()</function>.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- struct snd_info_entry *entry;
- int err = snd_card_proc_new(card, "my-file", &entry);
-]]>
- </programlisting>
- </informalexample>
-
- where the second argument specifies the name of the proc file to be
- created. The above example will create a file
- <filename>my-file</filename> under the card directory,
- e.g. <filename>/proc/asound/card0/my-file</filename>.
- </para>
-
- <para>
- Like other components, the proc entry created via
- <function>snd_card_proc_new()</function> will be registered and
- released automatically in the card registration and release
- functions.
- </para>
-
- <para>
- When the creation is successful, the function stores a new
- instance in the pointer given in the third argument.
- It is initialized as a text proc file for read only. To use
- this proc file as a read-only text file as it is, set the read
- callback with a private data via
- <function>snd_info_set_text_ops()</function>.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_info_set_text_ops(entry, chip, my_proc_read);
-]]>
- </programlisting>
- </informalexample>
-
- where the second argument (<parameter>chip</parameter>) is the
- private data to be used in the callbacks. The third parameter
- specifies the read buffer size and the fourth
- (<parameter>my_proc_read</parameter>) is the callback function, which
- is defined like
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static void my_proc_read(struct snd_info_entry *entry,
- struct snd_info_buffer *buffer);
-]]>
- </programlisting>
- </informalexample>
-
- </para>
-
- <para>
- In the read callback, use <function>snd_iprintf()</function> for
- output strings, which works just like normal
- <function>printf()</function>. For example,
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static void my_proc_read(struct snd_info_entry *entry,
- struct snd_info_buffer *buffer)
- {
- struct my_chip *chip = entry->private_data;
-
- snd_iprintf(buffer, "This is my chip!\n");
- snd_iprintf(buffer, "Port = %ld\n", chip->port);
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The file permissions can be changed afterwards. As default, it's
- set as read only for all users. If you want to add write
- permission for the user (root as default), do as follows:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- entry->mode = S_IFREG | S_IRUGO | S_IWUSR;
-]]>
- </programlisting>
- </informalexample>
-
- and set the write buffer size and the callback
-
- <informalexample>
- <programlisting>
-<![CDATA[
- entry->c.text.write = my_proc_write;
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- For the write callback, you can use
- <function>snd_info_get_line()</function> to get a text line, and
- <function>snd_info_get_str()</function> to retrieve a string from
- the line. Some examples are found in
- <filename>core/oss/mixer_oss.c</filename>, core/oss/and
- <filename>pcm_oss.c</filename>.
- </para>
-
- <para>
- For a raw-data proc-file, set the attributes as follows:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static struct snd_info_entry_ops my_file_io_ops = {
- .read = my_file_io_read,
- };
-
- entry->content = SNDRV_INFO_CONTENT_DATA;
- entry->private_data = chip;
- entry->c.ops = &my_file_io_ops;
- entry->size = 4096;
- entry->mode = S_IFREG | S_IRUGO;
-]]>
- </programlisting>
- </informalexample>
-
- For the raw data, <structfield>size</structfield> field must be
- set properly. This specifies the maximum size of the proc file access.
- </para>
-
- <para>
- The read/write callbacks of raw mode are more direct than the text mode.
- You need to use a low-level I/O functions such as
- <function>copy_from/to_user()</function> to transfer the
- data.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static ssize_t my_file_io_read(struct snd_info_entry *entry,
- void *file_private_data,
- struct file *file,
- char *buf,
- size_t count,
- loff_t pos)
- {
- if (copy_to_user(buf, local_data + pos, count))
- return -EFAULT;
- return count;
- }
-]]>
- </programlisting>
- </informalexample>
-
- If the size of the info entry has been set up properly,
- <structfield>count</structfield> and <structfield>pos</structfield> are
- guaranteed to fit within 0 and the given size.
- You don't have to check the range in the callbacks unless any
- other condition is required.
-
- </para>
-
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- Power Management -->
-<!-- ****************************************************** -->
- <chapter id="power-management">
- <title>Power Management</title>
- <para>
- If the chip is supposed to work with suspend/resume
- functions, you need to add power-management code to the
- driver. The additional code for power-management should be
- <function>ifdef</function>'ed with
- <constant>CONFIG_PM</constant>.
- </para>
-
- <para>
- If the driver <emphasis>fully</emphasis> supports suspend/resume
- that is, the device can be
- properly resumed to its state when suspend was called,
- you can set the <constant>SNDRV_PCM_INFO_RESUME</constant> flag
- in the pcm info field. Usually, this is possible when the
- registers of the chip can be safely saved and restored to
- RAM. If this is set, the trigger callback is called with
- <constant>SNDRV_PCM_TRIGGER_RESUME</constant> after the resume
- callback completes.
- </para>
-
- <para>
- Even if the driver doesn't support PM fully but
- partial suspend/resume is still possible, it's still worthy to
- implement suspend/resume callbacks. In such a case, applications
- would reset the status by calling
- <function>snd_pcm_prepare()</function> and restart the stream
- appropriately. Hence, you can define suspend/resume callbacks
- below but don't set <constant>SNDRV_PCM_INFO_RESUME</constant>
- info flag to the PCM.
- </para>
-
- <para>
- Note that the trigger with SUSPEND can always be called when
- <function>snd_pcm_suspend_all</function> is called,
- regardless of the <constant>SNDRV_PCM_INFO_RESUME</constant> flag.
- The <constant>RESUME</constant> flag affects only the behavior
- of <function>snd_pcm_resume()</function>.
- (Thus, in theory,
- <constant>SNDRV_PCM_TRIGGER_RESUME</constant> isn't needed
- to be handled in the trigger callback when no
- <constant>SNDRV_PCM_INFO_RESUME</constant> flag is set. But,
- it's better to keep it for compatibility reasons.)
- </para>
- <para>
- In the earlier version of ALSA drivers, a common
- power-management layer was provided, but it has been removed.
- The driver needs to define the suspend/resume hooks according to
- the bus the device is connected to. In the case of PCI drivers, the
- callbacks look like below:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- #ifdef CONFIG_PM
- static int snd_my_suspend(struct pci_dev *pci, pm_message_t state)
- {
- .... /* do things for suspend */
- return 0;
- }
- static int snd_my_resume(struct pci_dev *pci)
- {
- .... /* do things for suspend */
- return 0;
- }
- #endif
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The scheme of the real suspend job is as follows.
-
- <orderedlist>
- <listitem><para>Retrieve the card and the chip data.</para></listitem>
- <listitem><para>Call <function>snd_power_change_state()</function> with
- <constant>SNDRV_CTL_POWER_D3hot</constant> to change the
- power status.</para></listitem>
- <listitem><para>Call <function>snd_pcm_suspend_all()</function> to suspend the running PCM streams.</para></listitem>
- <listitem><para>If AC97 codecs are used, call
- <function>snd_ac97_suspend()</function> for each codec.</para></listitem>
- <listitem><para>Save the register values if necessary.</para></listitem>
- <listitem><para>Stop the hardware if necessary.</para></listitem>
- <listitem><para>Disable the PCI device by calling
- <function>pci_disable_device()</function>. Then, call
- <function>pci_save_state()</function> at last.</para></listitem>
- </orderedlist>
- </para>
-
- <para>
- A typical code would be like:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int mychip_suspend(struct pci_dev *pci, pm_message_t state)
- {
- /* (1) */
- struct snd_card *card = pci_get_drvdata(pci);
- struct mychip *chip = card->private_data;
- /* (2) */
- snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
- /* (3) */
- snd_pcm_suspend_all(chip->pcm);
- /* (4) */
- snd_ac97_suspend(chip->ac97);
- /* (5) */
- snd_mychip_save_registers(chip);
- /* (6) */
- snd_mychip_stop_hardware(chip);
- /* (7) */
- pci_disable_device(pci);
- pci_save_state(pci);
- return 0;
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- The scheme of the real resume job is as follows.
-
- <orderedlist>
- <listitem><para>Retrieve the card and the chip data.</para></listitem>
- <listitem><para>Set up PCI. First, call <function>pci_restore_state()</function>.
- Then enable the pci device again by calling <function>pci_enable_device()</function>.
- Call <function>pci_set_master()</function> if necessary, too.</para></listitem>
- <listitem><para>Re-initialize the chip.</para></listitem>
- <listitem><para>Restore the saved registers if necessary.</para></listitem>
- <listitem><para>Resume the mixer, e.g. calling
- <function>snd_ac97_resume()</function>.</para></listitem>
- <listitem><para>Restart the hardware (if any).</para></listitem>
- <listitem><para>Call <function>snd_power_change_state()</function> with
- <constant>SNDRV_CTL_POWER_D0</constant> to notify the processes.</para></listitem>
- </orderedlist>
- </para>
-
- <para>
- A typical code would be like:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int mychip_resume(struct pci_dev *pci)
- {
- /* (1) */
- struct snd_card *card = pci_get_drvdata(pci);
- struct mychip *chip = card->private_data;
- /* (2) */
- pci_restore_state(pci);
- pci_enable_device(pci);
- pci_set_master(pci);
- /* (3) */
- snd_mychip_reinit_chip(chip);
- /* (4) */
- snd_mychip_restore_registers(chip);
- /* (5) */
- snd_ac97_resume(chip->ac97);
- /* (6) */
- snd_mychip_restart_chip(chip);
- /* (7) */
- snd_power_change_state(card, SNDRV_CTL_POWER_D0);
- return 0;
- }
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- As shown in the above, it's better to save registers after
- suspending the PCM operations via
- <function>snd_pcm_suspend_all()</function> or
- <function>snd_pcm_suspend()</function>. It means that the PCM
- streams are already stopped when the register snapshot is
- taken. But, remember that you don't have to restart the PCM
- stream in the resume callback. It'll be restarted via
- trigger call with <constant>SNDRV_PCM_TRIGGER_RESUME</constant>
- when necessary.
- </para>
-
- <para>
- OK, we have all callbacks now. Let's set them up. In the
- initialization of the card, make sure that you can get the chip
- data from the card instance, typically via
- <structfield>private_data</structfield> field, in case you
- created the chip data individually.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_mychip_probe(struct pci_dev *pci,
- const struct pci_device_id *pci_id)
- {
- ....
- struct snd_card *card;
- struct mychip *chip;
- int err;
- ....
- err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
- 0, &card);
- ....
- chip = kzalloc(sizeof(*chip), GFP_KERNEL);
- ....
- card->private_data = chip;
- ....
- }
-]]>
- </programlisting>
- </informalexample>
-
- When you created the chip data with
- <function>snd_card_new()</function>, it's anyway accessible
- via <structfield>private_data</structfield> field.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int snd_mychip_probe(struct pci_dev *pci,
- const struct pci_device_id *pci_id)
- {
- ....
- struct snd_card *card;
- struct mychip *chip;
- int err;
- ....
- err = snd_card_new(&pci->dev, index[dev], id[dev], THIS_MODULE,
- sizeof(struct mychip), &card);
- ....
- chip = card->private_data;
- ....
- }
-]]>
- </programlisting>
- </informalexample>
-
- </para>
-
- <para>
- If you need a space to save the registers, allocate the
- buffer for it here, too, since it would be fatal
- if you cannot allocate a memory in the suspend phase.
- The allocated buffer should be released in the corresponding
- destructor.
- </para>
-
- <para>
- And next, set suspend/resume callbacks to the pci_driver.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static struct pci_driver driver = {
- .name = KBUILD_MODNAME,
- .id_table = snd_my_ids,
- .probe = snd_my_probe,
- .remove = snd_my_remove,
- #ifdef CONFIG_PM
- .suspend = snd_my_suspend,
- .resume = snd_my_resume,
- #endif
- };
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- Module Parameters -->
-<!-- ****************************************************** -->
- <chapter id="module-parameters">
- <title>Module Parameters</title>
- <para>
- There are standard module options for ALSA. At least, each
- module should have the <parameter>index</parameter>,
- <parameter>id</parameter> and <parameter>enable</parameter>
- options.
- </para>
-
- <para>
- If the module supports multiple cards (usually up to
- 8 = <constant>SNDRV_CARDS</constant> cards), they should be
- arrays. The default initial values are defined already as
- constants for easier programming:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;
- static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;
- static int enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE_PNP;
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- If the module supports only a single card, they could be single
- variables, instead. <parameter>enable</parameter> option is not
- always necessary in this case, but it would be better to have a
- dummy option for compatibility.
- </para>
-
- <para>
- The module parameters must be declared with the standard
- <function>module_param()()</function>,
- <function>module_param_array()()</function> and
- <function>MODULE_PARM_DESC()</function> macros.
- </para>
-
- <para>
- The typical coding would be like below:
-
- <informalexample>
- <programlisting>
-<![CDATA[
- #define CARD_NAME "My Chip"
-
- module_param_array(index, int, NULL, 0444);
- MODULE_PARM_DESC(index, "Index value for " CARD_NAME " soundcard.");
- module_param_array(id, charp, NULL, 0444);
- MODULE_PARM_DESC(id, "ID string for " CARD_NAME " soundcard.");
- module_param_array(enable, bool, NULL, 0444);
- MODULE_PARM_DESC(enable, "Enable " CARD_NAME " soundcard.");
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- Also, don't forget to define the module description, classes,
- license and devices. Especially, the recent modprobe requires to
- define the module license as GPL, etc., otherwise the system is
- shown as <quote>tainted</quote>.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- MODULE_DESCRIPTION("My Chip");
- MODULE_LICENSE("GPL");
- MODULE_SUPPORTED_DEVICE("{{Vendor,My Chip Name}}");
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- </chapter>
-
-
-<!-- ****************************************************** -->
-<!-- How To Put Your Driver -->
-<!-- ****************************************************** -->
- <chapter id="how-to-put-your-driver">
- <title>How To Put Your Driver Into ALSA Tree</title>
- <section>
- <title>General</title>
- <para>
- So far, you've learned how to write the driver codes.
- And you might have a question now: how to put my own
- driver into the ALSA driver tree?
- Here (finally :) the standard procedure is described briefly.
- </para>
-
- <para>
- Suppose that you create a new PCI driver for the card
- <quote>xyz</quote>. The card module name would be
- snd-xyz. The new driver is usually put into the alsa-driver
- tree, <filename>alsa-driver/pci</filename> directory in
- the case of PCI cards.
- Then the driver is evaluated, audited and tested
- by developers and users. After a certain time, the driver
- will go to the alsa-kernel tree (to the corresponding directory,
- such as <filename>alsa-kernel/pci</filename>) and eventually
- will be integrated into the Linux 2.6 tree (the directory would be
- <filename>linux/sound/pci</filename>).
- </para>
-
- <para>
- In the following sections, the driver code is supposed
- to be put into alsa-driver tree. The two cases are covered:
- a driver consisting of a single source file and one consisting
- of several source files.
- </para>
- </section>
-
- <section>
- <title>Driver with A Single Source File</title>
- <para>
- <orderedlist>
- <listitem>
- <para>
- Modify alsa-driver/pci/Makefile
- </para>
-
- <para>
- Suppose you have a file xyz.c. Add the following
- two lines
- <informalexample>
- <programlisting>
-<![CDATA[
- snd-xyz-objs := xyz.o
- obj-$(CONFIG_SND_XYZ) += snd-xyz.o
-]]>
- </programlisting>
- </informalexample>
- </para>
- </listitem>
-
- <listitem>
- <para>
- Create the Kconfig entry
- </para>
-
- <para>
- Add the new entry of Kconfig for your xyz driver.
- <informalexample>
- <programlisting>
-<![CDATA[
- config SND_XYZ
- tristate "Foobar XYZ"
- depends on SND
- select SND_PCM
- help
- Say Y here to include support for Foobar XYZ soundcard.
-
- To compile this driver as a module, choose M here: the module
- will be called snd-xyz.
-]]>
- </programlisting>
- </informalexample>
-
- the line, select SND_PCM, specifies that the driver xyz supports
- PCM. In addition to SND_PCM, the following components are
- supported for select command:
- SND_RAWMIDI, SND_TIMER, SND_HWDEP, SND_MPU401_UART,
- SND_OPL3_LIB, SND_OPL4_LIB, SND_VX_LIB, SND_AC97_CODEC.
- Add the select command for each supported component.
- </para>
-
- <para>
- Note that some selections imply the lowlevel selections.
- For example, PCM includes TIMER, MPU401_UART includes RAWMIDI,
- AC97_CODEC includes PCM, and OPL3_LIB includes HWDEP.
- You don't need to give the lowlevel selections again.
- </para>
-
- <para>
- For the details of Kconfig script, refer to the kbuild
- documentation.
- </para>
-
- </listitem>
-
- <listitem>
- <para>
- Run cvscompile script to re-generate the configure script and
- build the whole stuff again.
- </para>
- </listitem>
- </orderedlist>
- </para>
- </section>
-
- <section>
- <title>Drivers with Several Source Files</title>
- <para>
- Suppose that the driver snd-xyz have several source files.
- They are located in the new subdirectory,
- pci/xyz.
-
- <orderedlist>
- <listitem>
- <para>
- Add a new directory (<filename>xyz</filename>) in
- <filename>alsa-driver/pci/Makefile</filename> as below
-
- <informalexample>
- <programlisting>
-<![CDATA[
- obj-$(CONFIG_SND) += xyz/
-]]>
- </programlisting>
- </informalexample>
- </para>
- </listitem>
-
- <listitem>
- <para>
- Under the directory <filename>xyz</filename>, create a Makefile
-
- <example>
- <title>Sample Makefile for a driver xyz</title>
- <programlisting>
-<![CDATA[
- ifndef SND_TOPDIR
- SND_TOPDIR=../..
- endif
-
- include $(SND_TOPDIR)/toplevel.config
- include $(SND_TOPDIR)/Makefile.conf
-
- snd-xyz-objs := xyz.o abc.o def.o
-
- obj-$(CONFIG_SND_XYZ) += snd-xyz.o
-
- include $(SND_TOPDIR)/Rules.make
-]]>
- </programlisting>
- </example>
- </para>
- </listitem>
-
- <listitem>
- <para>
- Create the Kconfig entry
- </para>
-
- <para>
- This procedure is as same as in the last section.
- </para>
- </listitem>
-
- <listitem>
- <para>
- Run cvscompile script to re-generate the configure script and
- build the whole stuff again.
- </para>
- </listitem>
- </orderedlist>
- </para>
- </section>
-
- </chapter>
-
-<!-- ****************************************************** -->
-<!-- Useful Functions -->
-<!-- ****************************************************** -->
- <chapter id="useful-functions">
- <title>Useful Functions</title>
-
- <section id="useful-functions-snd-printk">
- <title><function>snd_printk()</function> and friends</title>
- <para>
- ALSA provides a verbose version of the
- <function>printk()</function> function. If a kernel config
- <constant>CONFIG_SND_VERBOSE_PRINTK</constant> is set, this
- function prints the given message together with the file name
- and the line of the caller. The <constant>KERN_XXX</constant>
- prefix is processed as
- well as the original <function>printk()</function> does, so it's
- recommended to add this prefix, e.g.
-
- <informalexample>
- <programlisting>
-<![CDATA[
- snd_printk(KERN_ERR "Oh my, sorry, it's extremely bad!\n");
-]]>
- </programlisting>
- </informalexample>
- </para>
-
- <para>
- There are also <function>printk()</function>'s for
- debugging. <function>snd_printd()</function> can be used for
- general debugging purposes. If
- <constant>CONFIG_SND_DEBUG</constant> is set, this function is
- compiled, and works just like
- <function>snd_printk()</function>. If the ALSA is compiled
- without the debugging flag, it's ignored.
- </para>
-
- <para>
- <function>snd_printdd()</function> is compiled in only when
- <constant>CONFIG_SND_DEBUG_VERBOSE</constant> is set. Please note
- that <constant>CONFIG_SND_DEBUG_VERBOSE</constant> is not set as default
- even if you configure the alsa-driver with
- <option>--with-debug=full</option> option. You need to give
- explicitly <option>--with-debug=detect</option> option instead.
- </para>
- </section>