[PATCH V4 3/5] dmaengine/dw_dmac: Divide one sg to many desc, if sg len is greater than DWC_MAX_COUNT

If len passed in sg for slave_sg transfers is greater than DWC_MAX_COUNT, then
driver programmes controller incorrectly.  This patch adds code to handle this
situation by allocation more than one desc for same sg.

Signed-off-by: Viresh Kumar <redacted>
---
 drivers/dma/dw_dmac.c |   65 +++++++++++++++++++++++++++++++++----------------
 1 files changed, 44 insertions(+), 21 deletions(-)

diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index 75b32e1..1662452 100644
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c

@@ -695,9 +695,15 @@ dwc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 		reg = dws->tx_reg;
 		for_each_sg(sgl, sg, sg_len, i) {
 			struct dw_desc	*desc;
-			u32		len;
-			u32		mem;
+			u32		len, dlen, mem;
 
+			mem = sg_phys(sg);
+			len = sg_dma_len(sg);
+			mem_width = 2;