Add MEMCPY capability for imx-sdma driver.

Signed-off-by: Robin Gong <redacted>
---
 drivers/dma/imx-sdma.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 92 insertions(+), 3 deletions(-)

@@ -1318,6 +1347,63 @@ static struct sdma_desc *sdma_transfer_init(struct sdma_channel *sdmac,
 	return NULL;
 }
 
+static struct dma_async_tx_descriptor *sdma_prep_memcpy(
+		struct dma_chan *chan, dma_addr_t dma_dst,
+		dma_addr_t dma_src, size_t len, unsigned long flags)
+{
+	struct sdma_channel *sdmac = to_sdma_chan(chan);
+	struct sdma_engine *sdma = sdmac->sdma;
+	int channel = sdmac->channel;
+	size_t count;
+	int i = 0, param;
+	struct sdma_buffer_descriptor *bd;
+	struct sdma_desc *desc;
+
+	if (!chan || !len)
+		return NULL;
+
+	dev_dbg(sdma->dev, "memcpy: %pad->%pad, len=%zu, channel=%d.\n",
+		&dma_src, &dma_dst, len, channel);
+
+	desc = sdma_transfer_init(sdmac, DMA_MEM_TO_MEM,
+					len / SDMA_BD_MAX_CNT + 1);
+	if (!desc)
+		return NULL;
+
+	do {
+		count = min_t(size_t, len, SDMA_BD_MAX_CNT);
+		bd = &desc->bd[i];
+		bd->buffer_addr = dma_src;
+		bd->ext_buffer_addr = dma_dst;
+		bd->mode.count = count;
+		desc->chn_count += count;
+		/* align with sdma->dma_device.copy_align: 4bytes */
+		bd->mode.command = 0;
+
+		dma_src += count;
+		dma_dst += count;
+		len -= count;
+		i++;