[PATCH v2 2/2] dmaengine: xilinx: dpdma: Add support for cyclic dma mode

[Vishal Sagar <vishal.sagar@xxxxxxx>]

From: Rohit Visavalia <rohit.visavalia@xxxxxxxxxx>

This patch adds support for DPDMA cyclic dma mode,
DMA cyclic transfers are required by audio streaming.

Signed-off-by: Rohit Visavalia <rohit.visavalia@xxxxxxx>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xxxxxxx>
Signed-off-by: Vishal Sagar <vishal.sagar@xxxxxxx>

---
 drivers/dma/xilinx/xilinx_dpdma.c | 97 +++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)

diff --git a/drivers/dma/xilinx/xilinx_dpdma.c b/drivers/dma/xilinx/xilinx_dpdma.c
index 28d9af8f00f0..88ad2f35538a 100644
--- a/drivers/dma/xilinx/xilinx_dpdma.c
+++ b/drivers/dma/xilinx/xilinx_dpdma.c
@@ -669,6 +669,84 @@ static void xilinx_dpdma_chan_free_tx_desc(struct virt_dma_desc *vdesc)
 	kfree(desc);
 }
 
+/**
+ * xilinx_dpdma_chan_prep_cyclic - Prepare a cyclic dma descriptor
+ * @chan: DPDMA channel
+ * @buf_addr: buffer address
+ * @buf_len: buffer length
+ * @period_len: number of periods
+ * @flags: tx flags argument passed in to prepare function
+ *
+ * Prepare a tx descriptor incudling internal software/hardware descriptors
+ * for the given cyclic transaction.
+ *
+ * Return: A dma async tx descriptor on success, or NULL.
+ */
+static struct dma_async_tx_descriptor *
+xilinx_dpdma_chan_prep_cyclic(struct xilinx_dpdma_chan *chan,
+			      dma_addr_t buf_addr, size_t buf_len,
+			      size_t period_len, unsigned long flags)
+{
+	struct xilinx_dpdma_tx_desc *tx_desc;
+	struct xilinx_dpdma_sw_desc *sw_desc, *last = NULL;
+	unsigned int periods = buf_len / period_len;
+	unsigned int i;
+
+	tx_desc = xilinx_dpdma_chan_alloc_tx_desc(chan);
+	if (!tx_desc)
+		return (void *)tx_desc;
+
+	for (i = 0; i < periods; i++) {
+		struct xilinx_dpdma_hw_desc *hw_desc;
+
+		if (!IS_ALIGNED(buf_addr, XILINX_DPDMA_ALIGN_BYTES)) {
+			dev_err(chan->xdev->dev,
+				"buffer should be aligned at %d B\n",
+				XILINX_DPDMA_ALIGN_BYTES);
+			goto error;
+		}
+
+		sw_desc = xilinx_dpdma_chan_alloc_sw_desc(chan);
+		if (!sw_desc)
+			goto error;
+
+		xilinx_dpdma_sw_desc_set_dma_addrs(chan->xdev, sw_desc, last,
+						   &buf_addr, 1);
+		hw_desc = &sw_desc->hw;
+		hw_desc->xfer_size = period_len;
+		hw_desc->hsize_stride =
+			FIELD_PREP(XILINX_DPDMA_DESC_HSIZE_STRIDE_HSIZE_MASK,
+				   period_len) |
+			FIELD_PREP(XILINX_DPDMA_DESC_HSIZE_STRIDE_STRIDE_MASK,
+				   period_len);
+		hw_desc->control |= XILINX_DPDMA_DESC_CONTROL_PREEMBLE;
+		hw_desc->control |= XILINX_DPDMA_DESC_CONTROL_IGNORE_DONE;
+		hw_desc->control |= XILINX_DPDMA_DESC_CONTROL_COMPLETE_INTR;
+
+		list_add_tail(&sw_desc->node, &tx_desc->descriptors);
+
+		buf_addr += period_len;
+		last = sw_desc;
+	}
+
+	sw_desc = list_first_entry(&tx_desc->descriptors,
+				   struct xilinx_dpdma_sw_desc, node);
+	last->hw.next_desc = lower_32_bits(sw_desc->dma_addr);
+	if (chan->xdev->ext_addr)
+		last->hw.addr_ext |=
+			FIELD_PREP(XILINX_DPDMA_DESC_ADDR_EXT_NEXT_ADDR_MASK,
+				   upper_32_bits(sw_desc->dma_addr));
+
+	last->hw.control |= XILINX_DPDMA_DESC_CONTROL_LAST_OF_FRAME;
+
+	return vchan_tx_prep(&chan->vchan, &tx_desc->vdesc, flags);
+
+error:
+	xilinx_dpdma_chan_free_tx_desc(&tx_desc->vdesc);
+
+	return NULL;
+}
+
 /**
  * xilinx_dpdma_chan_prep_interleaved_dma - Prepare an interleaved dma
  *					    descriptor
@@ -1190,6 +1268,23 @@ static void xilinx_dpdma_chan_handle_err(struct xilinx_dpdma_chan *chan)
 /* -----------------------------------------------------------------------------
  * DMA Engine Operations
  */
+static struct dma_async_tx_descriptor *
+xilinx_dpdma_prep_dma_cyclic(struct dma_chan *dchan, dma_addr_t buf_addr,
+			     size_t buf_len, size_t period_len,
+			     enum dma_transfer_direction direction,
+			     unsigned long flags)
+{
+	struct xilinx_dpdma_chan *chan = to_xilinx_chan(dchan);
+
+	if (direction != DMA_MEM_TO_DEV)
+		return NULL;
+
+	if (buf_len % period_len)
+		return NULL;
+
+	return xilinx_dpdma_chan_prep_cyclic(chan, buf_addr, buf_len,
+						 period_len, flags);
+}
 
 static struct dma_async_tx_descriptor *
 xilinx_dpdma_prep_interleaved_dma(struct dma_chan *dchan,
@@ -1673,6 +1768,7 @@ static int xilinx_dpdma_probe(struct platform_device *pdev)
 
 	dma_cap_set(DMA_SLAVE, ddev->cap_mask);
 	dma_cap_set(DMA_PRIVATE, ddev->cap_mask);
+	dma_cap_set(DMA_CYCLIC, ddev->cap_mask);
 	dma_cap_set(DMA_INTERLEAVE, ddev->cap_mask);
 	dma_cap_set(DMA_REPEAT, ddev->cap_mask);
 	dma_cap_set(DMA_LOAD_EOT, ddev->cap_mask);
@@ -1680,6 +1776,7 @@ static int xilinx_dpdma_probe(struct platform_device *pdev)
 
 	ddev->device_alloc_chan_resources = xilinx_dpdma_alloc_chan_resources;
 	ddev->device_free_chan_resources = xilinx_dpdma_free_chan_resources;
+	ddev->device_prep_dma_cyclic = xilinx_dpdma_prep_dma_cyclic;
 	ddev->device_prep_interleaved_dma = xilinx_dpdma_prep_interleaved_dma;
 	/* TODO: Can we achieve better granularity ? */
 	ddev->device_tx_status = dma_cookie_status;
-- 
2.25.1