Message ID | 1372423153-6742-2-git-send-email-zhangfei.gao@linaro.org (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
On Friday 28 June 2013, Zhangfei Gao wrote: > 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>
On Fri, Jun 28, 2013 at 08:39:12PM +0800, Zhangfei Gao wrote: > 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> Applied, thanks ~Vinod
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 93f7992..78dbbe0 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 96d3e4a..4e1c843 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) \
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> --- drivers/dma/dmaengine.c | 26 ++++++++++++++++++++++++++ include/linux/dmaengine.h | 1 + 2 files changed, 27 insertions(+)