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Commit 7bb587f4 authored by Zhangfei Gao's avatar Zhangfei Gao Committed by Vinod Koul
Browse files

dmaengine: add interface of dma_get_slave_channel 



Suggested by Arnd, add dma_get_slave_channel interface
Dma host driver could get specific channel specificied by request line, rather than filter.

host example:
static struct dma_chan *xx_of_dma_simple_xlate(struct of_phandle_args *dma_spec,
		struct of_dma *ofdma)
{
	struct xx_dma_dev *d = ofdma->of_dma_data;
	unsigned int request = dma_spec->args[0];

	if (request > d->dma_requests)
		return NULL;

	return dma_get_slave_channel(&(d->chans[request].vc.chan));
}

probe:
of_dma_controller_register((&op->dev)->of_node, xx_of_dma_simple_xlate, d);

Signed-off-by: default avatarZhangfei Gao <zhangfei.gao@linaro.org>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarVinod Koul <vinod.koul@intel.com>
parent c095ba72

drivers/dma/dmaengine.c

+26 −0
Original line number Diff line number Diff line
@@ -503,6 +503,32 @@ static struct dma_chan *private_candidate(const dma_cap_mask_t *mask, 
	return NULL;

}



/**

 * dma_request_channel - try to get specific channel exclusively

 * @chan: target channel

 */

struct dma_chan *dma_get_slave_channel(struct dma_chan *chan)

{

	int err = -EBUSY;



	/* lock against __dma_request_channel */

	mutex_lock(&dma_list_mutex);



	if (chan->client_count == 0)

		err = dma_chan_get(chan);

	else

		chan = NULL;



	mutex_unlock(&dma_list_mutex);



	if (err)

		pr_debug("%s: failed to get %s: (%d)\n",

			__func__, dma_chan_name(chan), err);



	return chan;

}

EXPORT_SYMBOL_GPL(dma_get_slave_channel);



/**

 * dma_request_channel - try to allocate an exclusive channel

 * @mask: capabilities that the channel must satisfy

include/linux/dmaengine.h

+1 −0
Original line number Diff line number Diff line
@@ -995,6 +995,7 @@ int dma_async_device_register(struct dma_device *device); 
void dma_async_device_unregister(struct dma_device *device);

void dma_run_dependencies(struct dma_async_tx_descriptor *tx);

struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type);

struct dma_chan *dma_get_slave_channel(struct dma_chan *chan);

struct dma_chan *net_dma_find_channel(void);

#define dma_request_channel(mask, x, y) __dma_request_channel(&(mask), x, y)

#define dma_request_slave_channel_compat(mask, x, y, dev, name) \