[PATCH V4 2/2] dmaengine: add helper function to request a slave DMA channel
From: Jon Hunter <hidden>
Date: 2012-09-13 22:00:29
Also in:
linux-arm-kernel, linux-omap
Subsystem:
dma generic offload engine subsystem, the rest · Maintainers:
Vinod Koul, Linus Torvalds
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 <redacted> Cc: Benoit Cousson <redacted> Cc: Stephen Warren <redacted> Cc: Grant Likely <redacted> Cc: Russell King <redacted> Cc: Rob Herring <redacted> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Vinod Koul <redacted> Cc: Dan Williams <redacted> Signed-off-by: Jon Hunter <redacted> --- 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