dmaengine: xilinx_dma: commonize DMA copy size calculation

This patch removes a bit of duplicated code by introducing a new
function that implements calculations for DMA copy size, and
prepares for changes to the copy size calculation that will
happen in following patches.

Suggested-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 31 insertions, 8 deletions

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index 02880963092f..fd9f37bafab0 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -425,6 +425,7 @@ struct xilinx_dma_config {
  * @rxs_clk: DMA s2mm stream clock
  * @nr_channels: Number of channels DMA device supports
  * @chan_id: DMA channel identifier
+ * @max_buffer_len: Max buffer length
  */
 struct xilinx_dma_device {
         void __iomem *regs;
@@ -444,6 +445,7 @@ struct xilinx_dma_device {
         struct clk *rxs_clk;
         u32 nr_channels;
         u32 chan_id;
+        u32 max_buffer_len;
 };
 
 /* Macros */
@@ -960,6 +962,25 @@ static int xilinx_dma_alloc_chan_resources(struct dma_chan *dchan)
 }
 
 /**
+ * xilinx_dma_calc_copysize - Calculate the amount of data to copy
+ * @chan: Driver specific DMA channel
+ * @size: Total data that needs to be copied
+ * @done: Amount of data that has been already copied
+ *
+ * Return: Amount of data that has to be copied
+ */
+static int xilinx_dma_calc_copysize(struct xilinx_dma_chan *chan,
+                                    int size, int done)
+{
+        size_t copy;
+
+        copy = min_t(size_t, size - done,
+                     chan->xdev->max_buffer_len);
+
+        return copy;
+}
+
+/**
  * xilinx_dma_tx_status - Get DMA transaction status
  * @dchan: DMA channel
  * @cookie: Transaction identifier
@@ -992,7 +1013,7 @@ static enum dma_status xilinx_dma_tx_status(struct dma_chan *dchan,
                         list_for_each_entry(segment, &desc->segments, node) {
                                 hw = &segment->hw;
                                 residue += (hw->control - hw->status) &
-                                           XILINX_DMA_MAX_TRANS_LEN;
+                                           chan->xdev->max_buffer_len;
                         }
                 }
                 spin_unlock_irqrestore(&chan->lock, flags);
@@ -1254,7 +1275,7 @@ static void xilinx_cdma_start_transfer(struct xilinx_dma_chan *chan)
 
                 /* Start the transfer */
                 dma_ctrl_write(chan, XILINX_DMA_REG_BTT,
-                                hw->control & XILINX_DMA_MAX_TRANS_LEN);
+                                hw->control & chan->xdev->max_buffer_len);
         }
 
         list_splice_tail_init(&chan->pending_list, &chan->active_list);
@@ -1357,7 +1378,7 @@ static void xilinx_dma_start_transfer(struct xilinx_dma_chan *chan)
 
                 /* Start the transfer */
                 dma_ctrl_write(chan, XILINX_DMA_REG_BTT,
-                               hw->control & XILINX_DMA_MAX_TRANS_LEN);
+                               hw->control & chan->xdev->max_buffer_len);
         }
 
         list_splice_tail_init(&chan->pending_list, &chan->active_list);
@@ -1718,7 +1739,7 @@ xilinx_cdma_prep_memcpy(struct dma_chan *dchan, dma_addr_t dma_dst,
         struct xilinx_cdma_tx_segment *segment;
         struct xilinx_cdma_desc_hw *hw;
 
-        if (!len || len > XILINX_DMA_MAX_TRANS_LEN)
+        if (!len || len > chan->xdev->max_buffer_len)
                 return NULL;
 
         desc = xilinx_dma_alloc_tx_descriptor(chan);
@@ -1808,8 +1829,8 @@ static struct dma_async_tx_descriptor *xilinx_dma_prep_slave_sg(
                          * Calculate the maximum number of bytes to transfer,
                          * making sure it is less than the hw limit
                          */
-                        copy = min_t(size_t, sg_dma_len(sg) - sg_used,
-                                     XILINX_DMA_MAX_TRANS_LEN);
+                        copy = xilinx_dma_calc_copysize(chan, sg_dma_len(sg),
+                                                        sg_used);
                         hw = &segment->hw;
 
                         /* Fill in the descriptor */
@@ -1913,8 +1934,8 @@ static struct dma_async_tx_descriptor *xilinx_dma_prep_dma_cyclic(
                          * Calculate the maximum number of bytes to transfer,
                          * making sure it is less than the hw limit
                          */
-                        copy = min_t(size_t, period_len - sg_used,
-                                     XILINX_DMA_MAX_TRANS_LEN);
+                        copy = xilinx_dma_calc_copysize(chan, period_len,
+                                                        sg_used);
                         hw = &segment->hw;
                         xilinx_axidma_buf(chan, hw, buf_addr, sg_used,
                                           period_len * i);
@@ -2628,6 +2649,8 @@ static int xilinx_dma_probe(struct platform_device *pdev)
 
         /* Retrieve the DMA engine properties from the device tree */
         xdev->has_sg = of_property_read_bool(node, "xlnx,include-sg");
+        xdev->max_buffer_len = XILINX_DMA_MAX_TRANS_LEN;
+
         if (xdev->dma_config->dmatype == XDMA_TYPE_AXIDMA)
                 xdev->mcdma = of_property_read_bool(node, "xlnx,mcdma");