dma: add dma_get_any_slave_channel(), for use in of_xlate()

mmp_pdma.c implements a custom of_xlate() function that is 95% identical
to what Tegra will need. Create a function to implement the common part,
so everyone doesn't just cut/paste the implementation.

Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: dmaengine@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index ea806bd..4f08ee8 100644 (file)
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -535,6 +535,34 @@ struct dma_chan *dma_get_slave_channel(struct dma_chan *chan)
 }
 EXPORT_SYMBOL_GPL(dma_get_slave_channel);
 
+struct dma_chan *dma_get_any_slave_channel(struct dma_device *device)
+{
+       dma_cap_mask_t mask;
+       struct dma_chan *chan;
+       int err;
+
+       dma_cap_zero(mask);
+       dma_cap_set(DMA_SLAVE, mask);
+
+       /* lock against __dma_request_channel */
+       mutex_lock(&dma_list_mutex);
+
+       chan = private_candidate(&mask, device, NULL, NULL);
+       if (chan) {
+               err = dma_chan_get(chan);
+               if (err) {
+                       pr_debug("%s: failed to get %s: (%d)\n",
+                               __func__, dma_chan_name(chan), err);
+                       chan = NULL;
+               }
+       }
+
+       mutex_unlock(&dma_list_mutex);
+
+       return chan;
+}
+EXPORT_SYMBOL_GPL(dma_get_any_slave_channel);
+
 /**
  * __dma_request_channel - try to allocate an exclusive channel
  * @mask: capabilities that the channel must satisfy

diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
index dcb1e05..2998f1b 100644 (file)
--- a/drivers/dma/mmp_pdma.c
+++ b/drivers/dma/mmp_pdma.c
@@ -893,33 +893,17 @@ static struct dma_chan *mmp_pdma_dma_xlate(struct of_phandle_args *dma_spec,
                                           struct of_dma *ofdma)
 {
        struct mmp_pdma_device *d = ofdma->of_dma_data;
-       struct dma_chan *chan, *candidate;
+       struct dma_chan *chan;
+       struct mmp_pdma_chan *c;
 
-retry:
-       candidate = NULL;
-
-       /* walk the list of channels registered with the current instance and
-        * find one that is currently unused */
-       list_for_each_entry(chan, &d->device.channels, device_node)
-               if (chan->client_count == 0) {
-                       candidate = chan;
-                       break;
-               }
-
-       if (!candidate)
+       chan = dma_get_any_slave_channel(&d->device);
+       if (!chan)
                return NULL;
 
-       /* dma_get_slave_channel will return NULL if we lost a race between
-        * the lookup and the reservation */
-       chan = dma_get_slave_channel(candidate);
-
-       if (chan) {
-               struct mmp_pdma_chan *c = to_mmp_pdma_chan(chan);
-               c->drcmr = dma_spec->args[0];
-               return chan;
-       }
+       c = to_mmp_pdma_chan(chan);
+       c->drcmr = dma_spec->args[0];
 
-       goto retry;
+       return chan;
 }
 
 static int mmp_pdma_probe(struct platform_device *op)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 41cf0c3..09ef23e 100644 (file)
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -1079,6 +1079,7 @@ 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_get_slave_channel(struct dma_chan *chan);
+struct dma_chan *dma_get_any_slave_channel(struct dma_device *device);
 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) \