path: root/Documentation/acpi
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authorLinus Torvalds <>2014-01-21 09:40:46 -0800
committerLinus Torvalds <>2014-01-21 10:09:12 -0800
commit8e5096607280d4e103389bfe8f8b7decbf538ff6 (patch)
tree60352a466e96c7b36d41263d7590ee79e0aaff35 /Documentation/acpi
parent02d0a752460ea5dab34ce36c9ddc9c682e846a0d (diff)
parentde755c330512364d3396c7da0c20b1c20b3b08b2 (diff)
Merge tag 'gpio-v3.14-1' of git://
Pull GPIO tree bulk changes from Linus Walleij: "A big set this merge window, as we have much going on in this subsystem. The changes to other subsystems (notably a slew of ARM machines as I am doing away with their custom APIs) have all been ACKed to the extent possible. Major changes this time: - Some core improvements and cleanups to the new GPIO descriptor API. This seems to be working now so we can start the exodus to this API, moving gradually away from the global GPIO numberspace. - Incremental improvements to the ACPI GPIO core, and move the few GPIO ACPI clients we have to the GPIO descriptor API right *now* before we go any further. We actually managed to contain this *before* we started to litter the kernel with yet another hackish global numberspace for the ACPI GPIOs, which is a big win. - The RFkill GPIO driver and all platforms using it have been migrated to use the GPIO descriptors rather than fixed number assignments. Tegra machine has been migrated as part of this. - New drivers for MOXA ART, Xtensa GPIO32 and SMSC SCH311x. Those should be really good examples of how I expect a nice GPIO driver to look these days. - Do away with custom GPIO implementations on a major part of the ARM machines: ks8695, lpc32xx, mv78xx0. Make a first step towards the same in the horribly convoluted Samsung S3C include forest. We expect to continue to clean this up as we move forward. - Flag GPIO lines used for IRQ on adnp, bcm-kona, em, intel-mid and lynxpoint. This makes the GPIOlib core aware that a certain GPIO line is used for IRQs and can then enforce some semantics such as disallowing a GPIO line marked as in use for IRQ to be switched to output mode. - Drop all use of irq_set_chip_and_handler_name(). The name provided in these cases were just unhelpful tags like "mux" or "demux". - Extend the MCP23s08 driver to handle interrupts. - Minor incremental improvements for rcar, lynxpoint, em 74x164 and msm drivers. - Some non-urgent bug fixes here and there, duplicate #includes and that usual kind of cleanups" Fix up broken Kconfig file manually to make this all compile. * tag 'gpio-v3.14-1' of git:// (71 commits) gpio: mcp23s08: fix casting caused build warning gpio: mcp23s08: depend on OF_GPIO gpio: mcp23s08: Add irq functionality for i2c chips ARM: S5P[v210|c100|64x0]: Fix build error gpio: pxa: clamp gpio get value to [0,1] ARM: s3c24xx: explicit dependency on <plat/gpio-cfg.h> ARM: S3C[24|64]xx: move includes back under <mach/> scope Documentation / ACPI: update to GPIO descriptor API gpio / ACPI: get rid of acpi_gpio.h gpio / ACPI: register to ACPI events automatically mmc: sdhci-acpi: convert to use GPIO descriptor API ARM: s3c24xx: fix build error gpio: f7188x: set can_sleep attribute gpio: samsung: Update documentation gpio: samsung: Remove hardware.h inclusion gpio: xtensa: depend on HAVE_XTENSA_GPIO32 gpio: clps711x: Enable driver compilation with COMPILE_TEST gpio: clps711x: Use of_match_ptr() net: rfkill: gpio: convert to descriptor-based GPIO interface leds: s3c24xx: Fix build failure ...
Diffstat (limited to 'Documentation/acpi')
1 files changed, 7 insertions, 29 deletions
diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt
index b994bcb32b92..2a1519b87177 100644
--- a/Documentation/acpi/enumeration.txt
+++ b/Documentation/acpi/enumeration.txt
@@ -293,36 +293,13 @@ the device to the driver. For example:
These GPIO numbers are controller relative and path "\\_SB.PCI0.GPI0"
specifies the path to the controller. In order to use these GPIOs in Linux
-we need to translate them to the Linux GPIO numbers.
+we need to translate them to the corresponding Linux GPIO descriptors.
-In a simple case of just getting the Linux GPIO number from device
-resources one can use acpi_get_gpio_by_index() helper function. It takes
-pointer to the device and index of the GpioIo/GpioInt descriptor in the
-device resources list. For example:
+There is a standard GPIO API for that and is documented in
- int gpio_irq, gpio_power;
- int ret;
- gpio_irq = acpi_get_gpio_by_index(dev, 1, NULL);
- if (gpio_irq < 0)
- /* handle error */
- gpio_power = acpi_get_gpio_by_index(dev, 0, NULL);
- if (gpio_power < 0)
- /* handle error */
- /* Now we can use the GPIO numbers */
-Other GpioIo parameters must be converted first by the driver to be
-suitable to the gpiolib before passing them.
-In case of GpioInt resource an additional call to gpio_to_irq() must be
-done before calling request_irq().
-Note that the above API is ACPI specific and not recommended for drivers
-that need to support non-ACPI systems. The recommended way is to use
-the descriptor based GPIO interfaces. The above example looks like this
-when converted to the GPIO desc:
+In the above example we can get the corresponding two GPIO descriptors with
+a code like this:
#include <linux/gpio/consumer.h>
@@ -339,4 +316,5 @@ when converted to the GPIO desc:
/* Now we can use the GPIO descriptors */
-See also Documentation/gpio.txt.
+There are also devm_* versions of these functions which release the
+descriptors once the device is released.