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-rw-r--r--Documentation/acpi/enumeration.txt77
-rw-r--r--Documentation/devicetree/bindings/dma/atmel-dma.txt35
-rw-r--r--Documentation/dmatest.txt81
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.
-Examples:
+Example:
-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.
+
+Example:
+
+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
+command:
+ % 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
+debugfs.