path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2013-05-09 09:46:45 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-05-09 09:46:45 -0700
commit1763e735b0a093a6747078b3bd101f079e576ab6 (patch)
tree75203a3229977d12dc5a5990d1122e7a3d5f30fc /Documentation
parentb29bdba51924f6fd5971352ba111784dee3a5853 (diff)
parent3065c194670b61e213656ce25976d7c8a95e3c93 (diff)
Merge branch 'for-linus' of git://git.infradead.org/users/vkoul/slave-dma
Pull slave-dmaengine updates from Vinod Koul: "This time we have dmatest improvements from Andy along with dw_dmac fixes. He has also done support for acpi for dmanegine. Also we have bunch of fixes going in DT support for dmanegine for various folks. Then Haswell and other ioat changes from Dave and SUDMAC support from Shimoda." * 'for-linus' of git://git.infradead.org/users/vkoul/slave-dma: (53 commits) dma: tegra: implement suspend/resume callbacks dma:of: Use a mutex to protect the of_dma_list dma: of: Fix of_node reference leak dmaengine: sirf: move driver init from module_init to subsys_initcall sudmac: add support for SUDMAC dma: sh: add Kconfig at_hdmac: move to generic DMA binding ioatdma: ioat3_alloc_sed can be static ioatdma: Adding write back descriptor error status support for ioatdma 3.3 ioatdma: S1200 platforms ioatdma channel 2 and 3 falsely advertise RAID cap ioatdma: Adding support for 16 src PQ ops and super extended descriptors ioatdma: Removing hw bug workaround for CB3.x .2 and earlier dw_dmac: add ACPI support dmaengine: call acpi_dma_request_slave_channel as well dma: acpi-dma: introduce ACPI DMA helpers dma: of: Remove unnecessary list_empty check DMA: OF: Check properties value before running be32_to_cpup() on it DMA: of: Constant names ioatdma: skip silicon bug workaround for pq_align for cb3.3 ioatdma: Removing PQ val disable for cb3.3 ...
Diffstat (limited to 'Documentation')
3 files changed, 188 insertions, 5 deletions
diff --git a/Documentation/acpi/enumeration.txt b/Documentation/acpi/enumeration.txt
index b0d541042ac..d9be7a97dff 100644
--- a/Documentation/acpi/enumeration.txt
+++ b/Documentation/acpi/enumeration.txt
@@ -66,6 +66,83 @@ the ACPI device explicitly to acpi_platform_device_ids list defined in
drivers/acpi/acpi_platform.c. This limitation is only for the platform
devices, SPI and I2C devices are created automatically as described below.
+DMA support
+DMA controllers enumerated via ACPI should be registered in the system to
+provide generic access to their resources. For example, a driver that would
+like to be accessible to slave devices via generic API call
+dma_request_slave_channel() must register itself at the end of the probe
+function like this:
+ err = devm_acpi_dma_controller_register(dev, xlate_func, dw);
+ /* Handle the error if it's not a case of !CONFIG_ACPI */
+and implement custom xlate function if needed (usually acpi_dma_simple_xlate()
+is enough) which converts the FixedDMA resource provided by struct
+acpi_dma_spec into the corresponding DMA channel. A piece of code for that case
+could look like:
+ #ifdef CONFIG_ACPI
+ struct filter_args {
+ /* Provide necessary information for the filter_func */
+ ...
+ };
+ static bool filter_func(struct dma_chan *chan, void *param)
+ {
+ /* Choose the proper channel */
+ ...
+ }
+ static struct dma_chan *xlate_func(struct acpi_dma_spec *dma_spec,
+ struct acpi_dma *adma)
+ {
+ dma_cap_mask_t cap;
+ struct filter_args args;
+ /* Prepare arguments for filter_func */
+ ...
+ return dma_request_channel(cap, filter_func, &args);
+ }
+ #else
+ static struct dma_chan *xlate_func(struct acpi_dma_spec *dma_spec,
+ struct acpi_dma *adma)
+ {
+ return NULL;
+ }
+ #endif
+dma_request_slave_channel() will call xlate_func() for each registered DMA
+controller. In the xlate function the proper channel must be chosen based on
+information in struct acpi_dma_spec and the properties of the controller
+provided by struct acpi_dma.
+Clients must call dma_request_slave_channel() with the string parameter that
+corresponds to a specific FixedDMA resource. By default "tx" means the first
+entry of the FixedDMA resource array, "rx" means the second entry. The table
+below shows a layout:
+ Device (I2C0)
+ {
+ ...
+ Method (_CRS, 0, NotSerialized)
+ {
+ Name (DBUF, ResourceTemplate ()
+ {
+ FixedDMA (0x0018, 0x0004, Width32bit, _Y48)
+ FixedDMA (0x0019, 0x0005, Width32bit, )
+ })
+ ...
+ }
+ }
+So, the FixedDMA with request line 0x0018 is "tx" and next one is "rx" in
+this example.
+In robust cases the client unfortunately needs to call
+acpi_dma_request_slave_chan_by_index() directly and therefore choose the
+specific FixedDMA resource by its index.
SPI serial bus support
Slave devices behind SPI bus have SpiSerialBus resource attached to them.
diff --git a/Documentation/devicetree/bindings/dma/atmel-dma.txt b/Documentation/devicetree/bindings/dma/atmel-dma.txt
index 3c046ee6e8b..c80e8a3402f 100644
--- a/Documentation/devicetree/bindings/dma/atmel-dma.txt
+++ b/Documentation/devicetree/bindings/dma/atmel-dma.txt
@@ -1,14 +1,39 @@
* Atmel Direct Memory Access Controller (DMA)
Required properties:
-- compatible: Should be "atmel,<chip>-dma"
-- reg: Should contain DMA registers location and length
-- interrupts: Should contain DMA interrupt
+- compatible: Should be "atmel,<chip>-dma".
+- reg: Should contain DMA registers location and length.
+- interrupts: Should contain DMA interrupt.
+- #dma-cells: Must be <2>, used to represent the number of integer cells in
+the dmas property of client devices.
-dma@ffffec00 {
+dma0: dma@ffffec00 {
compatible = "atmel,at91sam9g45-dma";
reg = <0xffffec00 0x200>;
interrupts = <21>;
+ #dma-cells = <2>;
+DMA clients connected to the Atmel DMA controller must use the format
+described in the dma.txt file, using a three-cell specifier for each channel:
+a phandle plus two interger cells.
+The three cells in order are:
+1. A phandle pointing to the DMA controller.
+2. The memory interface (16 most significant bits), the peripheral interface
+(16 less significant bits).
+3. The peripheral identifier for the hardware handshaking interface. The
+identifier can be different for tx and rx.
+i2c0@i2c@f8010000 {
+ compatible = "atmel,at91sam9x5-i2c";
+ reg = <0xf8010000 0x100>;
+ interrupts = <9 4 6>;
+ dmas = <&dma0 1 7>,
+ <&dma0 1 8>;
+ dma-names = "tx", "rx";
diff --git a/Documentation/dmatest.txt b/Documentation/dmatest.txt
new file mode 100644
index 00000000000..279ac0a8c5b
--- /dev/null
+++ b/Documentation/dmatest.txt
@@ -0,0 +1,81 @@
+ DMA Test Guide
+ ==============
+ Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+This small document introduces how to test DMA drivers using dmatest module.
+ Part 1 - How to build the test module
+The menuconfig contains an option that could be found by following path:
+ Device Drivers -> DMA Engine support -> DMA Test client
+In the configuration file the option called CONFIG_DMATEST. The dmatest could
+be built as module or inside kernel. Let's consider those cases.
+ Part 2 - When dmatest is built as a module...
+After mounting debugfs and loading the module, the /sys/kernel/debug/dmatest
+folder with nodes will be created. They are the same as module parameters with
+addition of the 'run' node that controls run and stop phases of the test.
+Note that in this case test will not run on load automatically.
+Example of usage:
+ % echo dma0chan0 > /sys/kernel/debug/dmatest/channel
+ % echo 2000 > /sys/kernel/debug/dmatest/timeout
+ % echo 1 > /sys/kernel/debug/dmatest/iterations
+ % echo 1 > /sys/kernel/debug/dmatest/run
+Hint: available channel list could be extracted by running the following
+ % ls -1 /sys/class/dma/
+After a while you will start to get messages about current status or error like
+in the original code.
+Note that running a new test will stop any in progress test.
+The following command should return actual state of the test.
+ % cat /sys/kernel/debug/dmatest/run
+To wait for test done the user may perform a busy loop that checks the state.
+ % while [ $(cat /sys/kernel/debug/dmatest/run) = "Y" ]
+ > do
+ > echo -n "."
+ > sleep 1
+ > done
+ > echo
+ Part 3 - When built-in in the kernel...
+The module parameters that is supplied to the kernel command line will be used
+for the first performed test. After user gets a control, the test could be
+interrupted or re-run with same or different parameters. For the details see
+the above section "Part 2 - When dmatest is built as a module..."
+In both cases the module parameters are used as initial values for the test case.
+You always could check them at run-time by running
+ % grep -H . /sys/module/dmatest/parameters/*
+ Part 4 - Gathering the test results
+The module provides a storage for the test results in the memory. The gathered
+data could be used after test is done.
+The special file 'results' in the debugfs represents gathered data of the in
+progress test. The messages collected are printed to the kernel log as well.
+Example of output:
+ % cat /sys/kernel/debug/dmatest/results
+ dma0chan0-copy0: #1: No errors with src_off=0x7bf dst_off=0x8ad len=0x3fea (0)
+The message format is unified across the different types of errors. A number in
+the parens represents additional information, e.g. error code, error counter,
+or status.
+Comparison between buffers is stored to the dedicated structure.
+Note that the verify result is now accessible only via file 'results' in the