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@xxxxxxxxx>
Cc: Benoit Cousson <b-cousson@xxxxxx>
Cc: Stephen Warren <swarren@xxxxxxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Rob Herring <rob.herring@xxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Vinod Koul <vinod.koul@xxxxxxxxx>
Cc: Dan Williams <djbw@xxxxxx>
Signed-off-by: Jon Hunter <jon-hunter@xxxxxx>
---
drivers/dma/dmaengine.c | 16 ++++++++++++++++
include/linux/dmaengine.h | 6 ++++++
2 files changed, 22 insertions(+)
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 3491654..9b466da 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 @@ struct dma_chan *__dma_request_channel(dma_cap_mask_t *mask, dma_filter_fn fn, v
}
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);
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 9c02a45..9500aa5 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -973,6 +973,7 @@ enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie);
enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx);
void dma_issue_pending_all(void);
struct dma_chan *__dma_request_channel(dma_cap_mask_t *mask, dma_filter_fn fn, void *fn_param);
+struct dma_chan *dma_request_slave_channel(struct device *dev, char *name);
void dma_release_channel(struct dma_chan *chan);
#else
static inline enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)
@@ -987,6 +988,11 @@ static inline struct dma_chan *__dma_request_channel(dma_cap_mask_t *mask,
{
return NULL;
}
+static inline struct dma_chan *dma_request_slave_channel(struct device *dev,
+ char *name)
+{
+ return NULL
+}
static inline void dma_release_channel(struct dma_chan *chan)
{
}
--
1.7.9.5
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