dmaengine: add helper function to request a slave DMA channel
Currently slave DMA channels are requested by calling dma_request_channel()
and requires DMA clients to pass various filter parameters to obtain the
appropriate channel.
With device-tree being used by architectures such as arm and the addition of
device-tree helper functions to extract the relevant DMA client information
from device-tree, add a new function to request a slave DMA channel using
device-tree. This function is currently a simple wrapper that calls the
device-tree of_dma_request_slave_channel() function.
Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Dan Williams <djbw@fb.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Reviewed-by: Stephen Warren <swarren@wwwdotorg.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index a815d44..d37cf95 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -62,6 +62,7 @@
#include <linux/rculist.h>
#include <linux/idr.h>
#include <linux/slab.h>
+#include <linux/of_dma.h>
static DEFINE_MUTEX(dma_list_mutex);
static DEFINE_IDR(dma_idr);
@@ -546,6 +547,21 @@
}
EXPORT_SYMBOL_GPL(__dma_request_channel);
+/**
+ * dma_request_slave_channel - try to allocate an exclusive slave channel
+ * @dev: pointer to client device structure
+ * @name: slave channel name
+ */
+struct dma_chan *dma_request_slave_channel(struct device *dev, char *name)
+{
+ /* If device-tree is present get slave info from here */
+ if (dev->of_node)
+ return of_dma_request_slave_channel(dev->of_node, name);
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(dma_request_slave_channel);
+
void dma_release_channel(struct dma_chan *chan)
{
mutex_lock(&dma_list_mutex);