diff options
| author | Zhangfei Gao <zhangfei.gao@linaro.org> | 2013-06-25 13:46:47 +0800 |
|---|---|---|
| committer | Zhangfei Gao <zhangfei.gao@linaro.org> | 2013-08-20 11:16:51 +0800 |
| commit | 70819037abfe1f5eb28bf3364e1c26d50b5661fd (patch) | |
| tree | 3f5f531f139068f805d3a526d6457a948e3d1bd6 | |
| parent | f285f2f24e0145ed148e88538f3e5e7bb92fd963 (diff) | |
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: Zhangfei Gao <zhangfei.gao@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
| -rw-r--r-- | drivers/dma/dmaengine.c | 26 | ||||
| -rw-r--r-- | include/linux/dmaengine.h | 1 |
2 files changed, 27 insertions, 0 deletions
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 93f7992bee5c..78dbbe09d7b1 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -504,6 +504,32 @@ static struct dma_chan *private_candidate(const dma_cap_mask_t *mask, } /** + * 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 * @fn: optional callback to disposition available channels diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index 96d3e4ab11a9..4e1c843895e7 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -1000,6 +1000,7 @@ 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) \ |