[PATCH v2 -next 4/7] dmaengine: xilinx_dma: Introduce xilinx_dma_get_residue

[Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>]

From: Nicholas Graumann <nick.graumann@gmail.com>

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>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
---
Changes for v2:
Fix merge failure due to changes in previous patch.
Invoke xilinx_dma_get_residue only for valid combination.
Fix multi-line comment style.
---
 drivers/dma/xilinx/xilinx_dma.c | 71 +++++++++++++++++++++++++++++++----------
 1 file changed, 54 insertions(+), 17 deletions(-)

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index 809e638..8c10686 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -788,6 +788,44 @@ 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;
+
+	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
  * @desc: dma transaction descriptor
@@ -996,8 +1034,6 @@ 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;
@@ -1006,22 +1042,20 @@ static enum dma_status xilinx_dma_tx_status(struct dma_chan *dchan,
 	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);
+	/*
+	 * VDMA and simple mode do not support residue reporting, so the
+	 * residue field will always be 0.
+	 */
+	if (chan->has_sg && chan->xdev->dma_config->dmatype != XDMA_TYPE_VDMA)
+		residue = xilinx_dma_get_residue(chan, desc);
 
-		dma_set_residue(txstate, residue);
-	}
+	spin_unlock_irqrestore(&chan->lock, flags);
+
+	dma_set_residue(txstate, residue);
 
 	return ret;
 }
@@ -2713,12 +2747,15 @@ static int xilinx_dma_probe(struct platform_device *pdev)
 					  xilinx_dma_prep_dma_cyclic;
 		xdev->common.device_prep_interleaved_dma =
 					xilinx_dma_prep_interleaved;
-		/* 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);
 		xdev->common.device_prep_dma_memcpy = xilinx_cdma_prep_memcpy;
+		/* 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;
-- 
2.7.4