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Commit 9a6cecc8 authored by Jon Hunter's avatar Jon Hunter Committed by Vinod Koul
Browse files

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: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarJon Hunter <jon-hunter@ti.com>
Reviewed-by: default avatarStephen Warren <swarren@wwwdotorg.org>
Acked-by: default avatarRob Herring <rob.herring@calxeda.com>
Signed-off-by: default avatarVinod Koul <vinod.koul@linux.intel.com>
parent d1c3ed66

drivers/dma/dmaengine.c

+16 −0
Original line number Original line Diff line number Diff line
@@ -62,6 +62,7 @@ 
#include <linux/rculist.h>

#include <linux/rculist.h>

#include <linux/idr.h>

#include <linux/idr.h>

#include <linux/slab.h>

#include <linux/slab.h>

#include <linux/of_dma.h>





static DEFINE_MUTEX(dma_list_mutex);

static DEFINE_MUTEX(dma_list_mutex);

static DEFINE_IDR(dma_idr);

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);

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)

void dma_release_channel(struct dma_chan *chan)

{

{

	mutex_lock(&dma_list_mutex);

	mutex_lock(&dma_list_mutex);

include/linux/dmaengine.h

+6 −0
Original line number Original line Diff line number Diff line
@@ -974,6 +974,7 @@ 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);

enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx);

void dma_issue_pending_all(void);

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_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);

void dma_release_channel(struct dma_chan *chan);

#else

#else

static inline enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)

static inline enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)
@@ -988,6 +989,11 @@ static inline struct dma_chan *__dma_request_channel(dma_cap_mask_t *mask, 
{

{

	return NULL;

	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)

static inline void dma_release_channel(struct dma_chan *chan)

{

{

}

}