dmaengine: xilinx_dma: Add callback_result support

Take advantage of dmaengine_desc_get_callback_invoke which allows either
a callback or callback_result to be specified. This can be useful when
using the AXI DMA transfer unknown quantities of data where the residue
contained in the result can be used to calculate the number of bytes
transferred.

Signed-off-by: Nicholas Graumann <nick.graumann@gmail.com>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Link: https://lore.kernel.org/r/1571150904-3988-6-git-send-email-radhey.shyam.pandey@xilinx.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/xilinx/xilinx_dma.c

@@ -300,12 +300,16 @@ struct xilinx_cdma_tx_segment {
  * @segments: TX segments list
  * @node: Node in the channel descriptors list
  * @cyclic: Check for cyclic transfers.
+ * @err: Whether the descriptor has an error.
+ * @residue: Residue of the completed descriptor
  */
 struct xilinx_dma_tx_descriptor {
 	struct dma_async_tx_descriptor async_tx;
 	struct list_head segments;
 	struct list_head node;
 	bool cyclic;
+	bool err;
+	u32 residue;
 };
 
 /**
@@ -856,6 +860,8 @@ static void xilinx_dma_chan_desc_cleanup(struct xilinx_dma_chan *chan)
 	spin_lock_irqsave(&chan->lock, flags);
 
 	list_for_each_entry_safe(desc, next, &chan->done_list, node) {
+		struct dmaengine_result result;
+
 		if (desc->cyclic) {
 			xilinx_dma_chan_handle_cyclic(chan, desc, &flags);
 			break;
@@ -864,9 +870,20 @@ static void xilinx_dma_chan_desc_cleanup(struct xilinx_dma_chan *chan)
 		/* Remove from the list of running transactions */
 		list_del(&desc->node);
 
+		if (unlikely(desc->err)) {
+			if (chan->direction == DMA_DEV_TO_MEM)
+				result.result = DMA_TRANS_READ_FAILED;
+			else
+				result.result = DMA_TRANS_WRITE_FAILED;
+		} else {
+			result.result = DMA_TRANS_NOERROR;
+		}
+
+		result.residue = desc->residue;
+
 		/* Run the link descriptor callback function */
 		spin_unlock_irqrestore(&chan->lock, flags);
-		dmaengine_desc_get_callback_invoke(&desc->async_tx, NULL);
+		dmaengine_desc_get_callback_invoke(&desc->async_tx, &result);
 		spin_lock_irqsave(&chan->lock, flags);
 
 		/* Run any dependencies, then free the descriptor */
@@ -1421,6 +1438,13 @@ static void xilinx_dma_complete_descriptor(struct xilinx_dma_chan *chan)
 		return;
 
 	list_for_each_entry_safe(desc, next, &chan->active_list, node) {
+		if (chan->has_sg && chan->xdev->dma_config->dmatype !=
+		    XDMA_TYPE_VDMA)
+			desc->residue = xilinx_dma_get_residue(chan, desc);
+		else
+			desc->residue = 0;
+		desc->err = chan->err;
+
 		list_del(&desc->node);
 		if (!desc->cyclic)
 			dma_cookie_complete(&desc->async_tx);