dmaengine: add channel device name to channel registration

Channel device name is used for sysfs, but also by dmatest filter function.

With dynamic channel registration, channels can be registered after dma
controller registration. Users may want to have specific channel names.

If name is NULL, the channel name relies on previous implementation,
dma<controller_device_id>chan<channel_device_id>.

Signed-off-by: Amelie Delaunay <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/dmaengine.c

···
 }
 
 static int __dma_async_device_channel_register(struct dma_device *device,
-					       struct dma_chan *chan)
+					       struct dma_chan *chan,
+					       const char *name)
 {
 	int rc;
 
···
 	chan->dev->device.parent = device->dev;
 	chan->dev->chan = chan;
 	chan->dev->dev_id = device->dev_id;
-	dev_set_name(&chan->dev->device, "dma%dchan%d",
-		     device->dev_id, chan->chan_id);
+	if (!name)
+		dev_set_name(&chan->dev->device, "dma%dchan%d", device->dev_id, chan->chan_id);
+	else
+		dev_set_name(&chan->dev->device, name);
 	rc = device_register(&chan->dev->device);
 	if (rc)
 		goto err_out_ida;
···
 }
 
 int dma_async_device_channel_register(struct dma_device *device,
-				      struct dma_chan *chan)
+				      struct dma_chan *chan,
+				      const char *name)
 {
 	int rc;
 
-	rc = __dma_async_device_channel_register(device, chan);
+	rc = __dma_async_device_channel_register(device, chan, name);
 	if (rc < 0)
 		return rc;
 
···
 
 	/* represent channels in sysfs. Probably want devs too */
 	list_for_each_entry(chan, &device->channels, device_node) {
-		rc = __dma_async_device_channel_register(device, chan);
+		rc = __dma_async_device_channel_register(device, chan, NULL);
 		if (rc < 0)
 			goto err_out;
 	}

drivers/dma/idxd/dma.c

···
 		desc->txd.tx_submit = idxd_dma_tx_submit;
 	}
 
-	rc = dma_async_device_channel_register(dma, chan);
+	rc = dma_async_device_channel_register(dma, chan, NULL);
 	if (rc < 0) {
 		kfree(idxd_chan);
 		return rc;

include/linux/dmaengine.h

···
 int dmaenginem_async_device_register(struct dma_device *device);
 void dma_async_device_unregister(struct dma_device *device);
 int dma_async_device_channel_register(struct dma_device *device,
-				      struct dma_chan *chan);
+				      struct dma_chan *chan,
+				      const char *name);
 void dma_async_device_channel_unregister(struct dma_device *device,
 					 struct dma_chan *chan);
 void dma_run_dependencies(struct dma_async_tx_descriptor *tx);