[RFC v2 PATCH 3/7] dmaengine: xilinx_dma: Pass AXI4-Stream control words to dma client

[Radhey Shyam Pandey]

Read DT property to check if AXI DMA is connected to streaming IP
i.e axiethernet. If connected pass AXI4-Stream control words to
dma client using metadata_ops dmaengine API.

Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xxxxxxxxxx>
---
Changes for v2:
- Use descriptor metadata API to pass control words to dma client.
- Rephrased commit description to be inline with implementation.
---
 drivers/dma/xilinx/xilinx_dma.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/dma/xilinx/xilinx_dma.c b/drivers/dma/xilinx/xilinx_dma.c
index 3aded7861fef..14dcfc473e52 100644
--- a/drivers/dma/xilinx/xilinx_dma.c
+++ b/drivers/dma/xilinx/xilinx_dma.c
@@ -491,6 +491,7 @@ struct xilinx_dma_config {
  * @s2mm_chan_id: DMA s2mm channel identifier
  * @mm2s_chan_id: DMA mm2s channel identifier
  * @max_buffer_len: Max buffer length
+ * @has_axistream_connected: AXI DMA connected to AXI Stream IP
  */
 struct xilinx_dma_device {
 	void __iomem *regs;
@@ -509,6 +510,7 @@ struct xilinx_dma_device {
 	u32 s2mm_chan_id;
 	u32 mm2s_chan_id;
 	u32 max_buffer_len;
+	bool has_axistream_connected;
 };
 
 /* Macros */
@@ -621,6 +623,29 @@ static inline void xilinx_aximcdma_buf(struct xilinx_dma_chan *chan,
 	}
 }
 
+/**
+ * xilinx_dma_get_metadata_ptr- Populate metadata pointer and payload length
+ * @tx: async transaction descriptor
+ * @payload_len: metadata payload length
+ * @max_len: metadata max length
+ * Return: The app field pointer.
+ */
+static void *xilinx_dma_get_metadata_ptr(struct dma_async_tx_descriptor *tx,
+					 size_t *payload_len, size_t *max_len)
+{
+	struct xilinx_dma_tx_descriptor *desc = to_dma_tx_descriptor(tx);
+	struct xilinx_axidma_tx_segment *seg;
+
+	*max_len = *payload_len = sizeof(u32) * XILINX_DMA_NUM_APP_WORDS;
+	seg = list_first_entry(&desc->segments,
+			       struct xilinx_axidma_tx_segment, node);
+	return seg->hw.app;
+}
+
+static struct dma_descriptor_metadata_ops xilinx_dma_metadata_ops = {
+	.get_ptr = xilinx_dma_get_metadata_ptr,
+};
+
 /* -----------------------------------------------------------------------------
  * Descriptors and segments alloc and free
  */
@@ -2200,6 +2225,9 @@ static struct dma_async_tx_descriptor *xilinx_dma_prep_slave_sg(
 		segment->hw.control |= XILINX_DMA_BD_EOP;
 	}
 
+	if (chan->xdev->has_axistream_connected)
+		desc->async_tx.metadata_ops = &xilinx_dma_metadata_ops;
+
 	return &desc->async_tx;
 
 error:
@@ -3032,6 +3060,11 @@ static int xilinx_dma_probe(struct platform_device *pdev)
 		}
 	}
 
+	if (xdev->dma_config->dmatype == XDMA_TYPE_AXIDMA) {
+		xdev->has_axistream_connected =
+			of_property_read_bool(node, "xlnx,axistream-connected");
+	}
+
 	if (xdev->dma_config->dmatype == XDMA_TYPE_VDMA) {
 		err = of_property_read_u32(node, "xlnx,num-fstores",
 					   &num_frames);
@@ -3057,6 +3090,10 @@ static int xilinx_dma_probe(struct platform_device *pdev)
 	else
 		xdev->ext_addr = false;
 
+	/* Set metadata mode */
+	if (xdev->has_axistream_connected)
+		xdev->common.desc_metadata_modes = DESC_METADATA_ENGINE;
+
 	/* Set the dma mask bits */
 	dma_set_mask(xdev->dev, DMA_BIT_MASK(addr_width));
 
-- 
2.7.4