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>
diff --git a/drivers/dma/acpi-dma.c b/drivers/dma/acpi-dma.c
index 5a63564..981a38f 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 @@
* 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;
+ int index;
- if (!strcmp(name, "tx"))
- index = 0;
- else if (!strcmp(name, "rx"))
- index = 1;
- else
- return ERR_PTR(-ENODEV);
+ 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);