dmaengine: xilinx: Introduce xilinx_dma_get_residue

Introduce a function that can calculate residues for IPs that support it:
AXI DMA and CDMA.

Signed-off-by: Nicholas Graumann <nick.graumann@gmail.com>
Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

Author: ravotus

��drivers/dma/xilinx/xilinx_dma.c

@@ -778,6 +778,51 @@ static void xilinx_dma_free_chan_resources(struct dma_chan *dchan)
 	}
 }
 
+/**
+ * xilinx_dma_get_residue - Compute residue for a given descriptor
+ * @chan: Driver specific dma channel
+ * @desc: dma transaction descriptor
+ *
+ * Return: The number of residue bytes for the descriptor.
+ */
+static u32 xilinx_dma_get_residue(struct xilinx_dma_chan *chan,
+				  struct xilinx_dma_tx_descriptor *desc)
+{
+	struct xilinx_cdma_tx_segment *cdma_seg;
+	struct xilinx_axidma_tx_segment *axidma_seg;
+	struct xilinx_cdma_desc_hw *cdma_hw;
+	struct xilinx_axidma_desc_hw *axidma_hw;
+	struct list_head *entry;
+	u32 residue = 0;
+
+	/**
+	 * VDMA and simple mode do not support residue reporting, so the
+	 * residue field will always be 0.
+	 */
+	if (chan->xdev->dma_config->dmatype == XDMA_TYPE_VDMA || !chan->has_sg)
+		return residue;
+
+	list_for_each(entry, &desc->segments) {
+		if (chan->xdev->dma_config->dmatype == XDMA_TYPE_CDMA) {
+			cdma_seg = list_entry(entry,
+					      struct xilinx_cdma_tx_segment,
+					      node);
+			cdma_hw = &cdma_seg->hw;
+			residue += (cdma_hw->control - cdma_hw->status) &
+				   chan->xdev->max_buffer_len;
+		} else {
+			axidma_seg = list_entry(entry,
+						struct xilinx_axidma_tx_segment,
+						node);
+			axidma_hw = &axidma_seg->hw;
+			residue += (axidma_hw->control - axidma_hw->status) &
+				   chan->xdev->max_buffer_len;
+		}
+	}
+
+	return residue;
+}
+
 /**
  * xilinx_dma_chan_handle_cyclic - Cyclic dma callback
  * @chan: Driver specific dma channel
@@ -959,33 +1004,22 @@ static enum dma_status xilinx_dma_tx_status(struct dma_chan *dchan,
 {
 	struct xilinx_dma_chan *chan = to_xilinx_chan(dchan);
 	struct xilinx_dma_tx_descriptor *desc;
-	struct xilinx_axidma_tx_segment *segment;
-	struct xilinx_axidma_desc_hw *hw;
 	enum dma_status ret;
 	unsigned long flags;
-	u32 residue = 0;
 
 	ret = dma_cookie_status(dchan, cookie, txstate);
 	if (ret == DMA_COMPLETE || !txstate)
 		return ret;
 
-	if (chan->xdev->dma_config->dmatype == XDMA_TYPE_AXIDMA) {
-		spin_lock_irqsave(&chan->lock, flags);
+	spin_lock_irqsave(&chan->lock, flags);
 
-		desc = list_last_entry(&chan->active_list,
-				       struct xilinx_dma_tx_descriptor, node);
-		if (chan->has_sg) {
-			list_for_each_entry(segment, &desc->segments, node) {
-				hw = &segment->hw;
-				residue += (hw->control - hw->status) &
-					   chan->xdev->max_buffer_len;
-			}
-		}
-		spin_unlock_irqrestore(&chan->lock, flags);
+	desc = list_last_entry(&chan->active_list,
+			       struct xilinx_dma_tx_descriptor, node);
+	chan->residue = xilinx_dma_get_residue(chan, desc);
 
-		chan->residue = residue;
-		dma_set_residue(txstate, chan->residue);
-	}
+	spin_unlock_irqrestore(&chan->lock, flags);
+
+	dma_set_residue(txstate, chan->residue);
 
 	return ret;
 }
@@ -2681,14 +2715,17 @@ static int xilinx_dma_probe(struct platform_device *pdev)
 		xdev->common.device_prep_slave_sg = xilinx_dma_prep_slave_sg;
 		xdev->common.device_prep_dma_cyclic =
 					  xilinx_dma_prep_dma_cyclic;
-		/* Residue calculation is supported by only AXI DMA */
+		/* Residue calculation is supported by only AXI DMA and CDMA */
 		xdev->common.residue_granularity =
 					  DMA_RESIDUE_GRANULARITY_SEGMENT;
 	} else if (xdev->dma_config->dmatype == XDMA_TYPE_CDMA) {
 		dma_cap_set(DMA_MEMCPY, xdev->common.cap_mask);
 		dma_cap_set(DMA_SG, xdev->common.cap_mask);
 		xdev->common.device_prep_dma_memcpy = xilinx_cdma_prep_memcpy;
 		xdev->common.device_prep_dma_sg = xilinx_cdma_prep_sg;
+		/* Residue calculation is supported by only AXI DMA and CDMA */
+		xdev->common.residue_granularity =
+					  DMA_RESIDUE_GRANULARITY_SEGMENT;
 	} else {
 		xdev->common.device_prep_interleaved_dma =
 				xilinx_vdma_dma_prep_interleaved;