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author | Mika Westerberg <mika.westerberg@linux.intel.com> | 2015-09-14 16:37:36 +0200 |
---|---|---|
committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2015-09-25 02:00:19 +0200 |
commit | 3f4232ee8b53cf2266d227af299aa511d2d91d11 (patch) | |
tree | 2ef4ce5560d372c2a75e7a5bbe00467b1a325e5c /drivers/dma/acpi-dma.c | |
parent | device property: Add fwnode_property_match_string() (diff) | |
download | linux-3f4232ee8b53cf2266d227af299aa511d2d91d11.tar.xz linux-3f4232ee8b53cf2266d227af299aa511d2d91d11.zip |
acpi-dma: Add support for "dma-names" device property
The current implementation hard codes the two supported channels so that
"tx" is always 0 and "rx" is always 1. This is because there has been no
suitable way in ACPI to name resources.
With _DSD device properties we can finally do this:
Device (SPI1) {
Name (_CRS, ResourceTemplate () {
...
FixedDMA (0x0000, 0x0000, Width32bit)
FixedDMA (0x0001, 0x0001, Width32bit)
})
Name (_DSD, Package () {
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
Package () {
Package () {"dma-names", Package () {"tx", "rx"}}
},
})
}
The names "tx" and "rx" now provide index of the FixedDMA resource in
question.
Modify acpi_dma_request_slave_chan_by_name() so that it looks for
"dma-names" property first and only then fall back using hardcoded indices.
The DT "dma-names" binding that we reuse for ACPI is documented in
Documentation/devicetree/bindings/dma/dma.txt.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/dma/acpi-dma.c')
-rw-r--r-- | drivers/dma/acpi-dma.c | 25 |
1 files changed, 17 insertions, 8 deletions
diff --git a/drivers/dma/acpi-dma.c b/drivers/dma/acpi-dma.c index 5a635646e05c..981a38fc4cb8 100644 --- a/drivers/dma/acpi-dma.c +++ b/drivers/dma/acpi-dma.c @@ -21,6 +21,7 @@ #include <linux/ioport.h> #include <linux/acpi.h> #include <linux/acpi_dma.h> +#include <linux/property.h> static LIST_HEAD(acpi_dma_list); static DEFINE_MUTEX(acpi_dma_lock); @@ -413,21 +414,29 @@ EXPORT_SYMBOL_GPL(acpi_dma_request_slave_chan_by_index); * translate the names "tx" and "rx" here based on the most common case where * the first FixedDMA descriptor is TX and second is RX. * + * If the device has "dma-names" property the FixedDMA descriptor indices + * are retrieved based on those. Otherwise the function falls back using + * hardcoded indices. + * * Return: * Pointer to appropriate dma channel on success or an error pointer. */ struct dma_chan *acpi_dma_request_slave_chan_by_name(struct device *dev, const char *name) { - size_t index; - - if (!strcmp(name, "tx")) - index = 0; - else if (!strcmp(name, "rx")) - index = 1; - else - return ERR_PTR(-ENODEV); + int index; + + index = device_property_match_string(dev, "dma-names", name); + if (index < 0) { + if (!strcmp(name, "tx")) + index = 0; + else if (!strcmp(name, "rx")) + index = 1; + else + return ERR_PTR(-ENODEV); + } + dev_dbg(dev, "found DMA channel \"%s\" at index %d\n", name, index); return acpi_dma_request_slave_chan_by_index(dev, index); } EXPORT_SYMBOL_GPL(acpi_dma_request_slave_chan_by_name); |