1 files changed, 62 insertions, 22 deletions

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index e057935e3023..f15712f2fec6 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -222,31 +222,35 @@ static void balance_ref_count(struct dma_chan *chan)
  */
 static int dma_chan_get(struct dma_chan *chan)
 {
-	int err = -ENODEV;
 	struct module *owner = dma_chan_to_owner(chan);
+	int ret;
 
+	/* The channel is already in use, update client count */
 	if (chan->client_count) {
 		__module_get(owner);
-		err = 0;
-	} else if (try_module_get(owner))
-		err = 0;
+		goto out;
+	}
 
-	if (err == 0)
-		chan->client_count++;
+	if (!try_module_get(owner))
+		return -ENODEV;
 
 	/* allocate upon first client reference */
-	if (chan->client_count == 1 && err == 0) {
-		int desc_cnt = chan->device->device_alloc_chan_resources(chan);
-
-		if (desc_cnt < 0) {
-			err = desc_cnt;
-			chan->client_count = 0;
-			module_put(owner);
-		} else if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
-			balance_ref_count(chan);
+	if (chan->device->device_alloc_chan_resources) {
+		ret = chan->device->device_alloc_chan_resources(chan);
+		if (ret < 0)
+			goto err_out;
 	}
 
-	return err;
+	if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
+		balance_ref_count(chan);
+
+out:
+	chan->client_count++;
+	return 0;
+
+err_out:
+	module_put(owner);
+	return ret;
 }
 
 /**
@@ -257,11 +261,15 @@ static int dma_chan_get(struct dma_chan *chan)
  */
 static void dma_chan_put(struct dma_chan *chan)
 {
+	/* This channel is not in use, bail out */
 	if (!chan->client_count)
-		return; /* this channel failed alloc_chan_resources */
+		return;
+
 	chan->client_count--;
 	module_put(dma_chan_to_owner(chan));
-	if (chan->client_count == 0)
+
+	/* This channel is not in use anymore, free it */
+	if (!chan->client_count && chan->device->device_free_chan_resources)
 		chan->device->device_free_chan_resources(chan);
 }
 
@@ -471,6 +479,39 @@ static void dma_channel_rebalance(void)
 		}
 }
 
+int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
+{
+	struct dma_device *device;
+
+	if (!chan || !caps)
+		return -EINVAL;
+
+	device = chan->device;
+
+	/* check if the channel supports slave transactions */
+	if (!test_bit(DMA_SLAVE, device->cap_mask.bits))
+		return -ENXIO;
+
+	/*
+	 * Check whether it reports it uses the generic slave
+	 * capabilities, if not, that means it doesn't support any
+	 * kind of slave capabilities reporting.
+	 */
+	if (!device->directions)
+		return -ENXIO;
+
+	caps->src_addr_widths = device->src_addr_widths;
+	caps->dst_addr_widths = device->dst_addr_widths;
+	caps->directions = device->directions;
+	caps->residue_granularity = device->residue_granularity;
+
+	caps->cmd_pause = !!device->device_pause;
+	caps->cmd_terminate = !!device->device_terminate_all;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dma_get_slave_caps);
+
 static struct dma_chan *private_candidate(const dma_cap_mask_t *mask,
 					  struct dma_device *dev,
 					  dma_filter_fn fn, void *fn_param)
@@ -811,17 +852,16 @@ int dma_async_device_register(struct dma_device *device)
 		!device->device_prep_dma_sg);
 	BUG_ON(dma_has_cap(DMA_CYCLIC, device->cap_mask) &&
 		!device->device_prep_dma_cyclic);
-	BUG_ON(dma_has_cap(DMA_SLAVE, device->cap_mask) &&
-		!device->device_control);
 	BUG_ON(dma_has_cap(DMA_INTERLEAVE, device->cap_mask) &&
 		!device->device_prep_interleaved_dma);
 
-	BUG_ON(!device->device_alloc_chan_resources);
-	BUG_ON(!device->device_free_chan_resources);
 	BUG_ON(!device->device_tx_status);
 	BUG_ON(!device->device_issue_pending);
 	BUG_ON(!device->dev);
 
+	WARN(dma_has_cap(DMA_SLAVE, device->cap_mask) && !device->directions,
+	     "this driver doesn't support generic slave capabilities reporting\n");
+
 	/* note: this only matters in the
 	 * CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH=n case
 	 */