dmaengine: Add consumer for the new DMA_MEMCPY_SG API function.

This new CDMA binding for device_prep_dma_memcpy_sg was partially borrowed
from xlnx kernel tree, an expanded with extended address space support when
linking descriptor segments and checking for incorrect zero transfer size.

Signed-off-by: Adrian Larumbe <adrianml@alumnos.upm.es>
Link: https://lore.kernel.org/r/20211101180825.241048-4-adrianml@alumnos.upm.es
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index 4677ce0..6161814 100644 (file)
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -2128,6 +2128,126 @@ error:
 }
 
 /**
+ * xilinx_cdma_prep_memcpy_sg - prepare descriptors for a memcpy_sg transaction
+ * @dchan: DMA channel
+ * @dst_sg: Destination scatter list
+ * @dst_sg_len: Number of entries in destination scatter list
+ * @src_sg: Source scatter list
+ * @src_sg_len: Number of entries in source scatter list
+ * @flags: transfer ack flags
+ *
+ * Return: Async transaction descriptor on success and NULL on failure
+ */
+static struct dma_async_tx_descriptor *xilinx_cdma_prep_memcpy_sg(
+                       struct dma_chan *dchan, struct scatterlist *dst_sg,
+                       unsigned int dst_sg_len, struct scatterlist *src_sg,
+                       unsigned int src_sg_len, unsigned long flags)
+{
+       struct xilinx_dma_chan *chan = to_xilinx_chan(dchan);
+       struct xilinx_dma_tx_descriptor *desc;
+       struct xilinx_cdma_tx_segment *segment, *prev = NULL;
+       struct xilinx_cdma_desc_hw *hw;
+       size_t len, dst_avail, src_avail;
+       dma_addr_t dma_dst, dma_src;
+
+       if (unlikely(dst_sg_len == 0 || src_sg_len == 0))
+               return NULL;
+
+       if (unlikely(!dst_sg  || !src_sg))
+               return NULL;
+
+       desc = xilinx_dma_alloc_tx_descriptor(chan);
+       if (!desc)
+               return NULL;
+
+       dma_async_tx_descriptor_init(&desc->async_tx, &chan->common);
+       desc->async_tx.tx_submit = xilinx_dma_tx_submit;
+
+       dst_avail = sg_dma_len(dst_sg);
+       src_avail = sg_dma_len(src_sg);
+       /*
+        * loop until there is either no more source or no more destination
+        * scatterlist entry
+        */
+       while (true) {
+               len = min_t(size_t, src_avail, dst_avail);
+               len = min_t(size_t, len, chan->xdev->max_buffer_len);
+               if (len == 0)
+                       goto fetch;
+
+               /* Allocate the link descriptor from DMA pool */
+               segment = xilinx_cdma_alloc_tx_segment(chan);
+               if (!segment)
+                       goto error;
+
+               dma_dst = sg_dma_address(dst_sg) + sg_dma_len(dst_sg) -
+                       dst_avail;
+               dma_src = sg_dma_address(src_sg) + sg_dma_len(src_sg) -
+                       src_avail;
+               hw = &segment->hw;
+               hw->control = len;
+               hw->src_addr = dma_src;
+               hw->dest_addr = dma_dst;
+               if (chan->ext_addr) {
+                       hw->src_addr_msb = upper_32_bits(dma_src);
+                       hw->dest_addr_msb = upper_32_bits(dma_dst);
+               }
+
+               if (prev) {
+                       prev->hw.next_desc = segment->phys;
+                       if (chan->ext_addr)
+                               prev->hw.next_desc_msb =
+                                       upper_32_bits(segment->phys);
+               }
+
+               prev = segment;
+               dst_avail -= len;
+               src_avail -= len;
+               list_add_tail(&segment->node, &desc->segments);
+
+fetch:
+               /* Fetch the next dst scatterlist entry */
+               if (dst_avail == 0) {
+                       if (dst_sg_len == 0)
+                               break;
+                       dst_sg = sg_next(dst_sg);
+                       if (dst_sg == NULL)
+                               break;
+                       dst_sg_len--;
+                       dst_avail = sg_dma_len(dst_sg);
+               }
+               /* Fetch the next src scatterlist entry */
+               if (src_avail == 0) {
+                       if (src_sg_len == 0)
+                               break;
+                       src_sg = sg_next(src_sg);
+                       if (src_sg == NULL)
+                               break;
+                       src_sg_len--;
+                       src_avail = sg_dma_len(src_sg);
+               }
+       }
+
+       if (list_empty(&desc->segments)) {
+               dev_err(chan->xdev->dev,
+                       "%s: Zero-size SG transfer requested\n", __func__);
+               goto error;
+       }
+
+       /* Link the last hardware descriptor with the first. */
+       segment = list_first_entry(&desc->segments,
+                               struct xilinx_cdma_tx_segment, node);
+       desc->async_tx.phys = segment->phys;
+       prev->hw.next_desc = segment->phys;
+
+       return &desc->async_tx;
+
+error:
+       xilinx_dma_free_tx_descriptor(chan, desc);
+       return NULL;
+}
+
+/**
  * xilinx_dma_prep_slave_sg - prepare descriptors for a DMA_SLAVE transaction
  * @dchan: DMA channel
  * @sgl: scatterlist to transfer to/from
@@ -3115,7 +3235,9 @@ static int xilinx_dma_probe(struct platform_device *pdev)
                                          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_MEMCPY_SG, xdev->common.cap_mask);
                xdev->common.device_prep_dma_memcpy = xilinx_cdma_prep_memcpy;
+               xdev->common.device_prep_dma_memcpy_sg = xilinx_cdma_prep_memcpy_sg;
                /* Residue calculation is supported by only AXI DMA and CDMA */
                xdev->common.residue_granularity =
                                          DMA_RESIDUE_GRANULARITY_SEGMENT;