[v4,1/1] dmaengine: dw-axi-dmac: Support src_maxburst and dst_maxburst

[Tan En De <endeneer@xxxxxxxxx>]

Current implementation has hardcoded CHx_CTL.SRC_MSIZE and
CHx_CTL.DST_MSIZE with a constant, namely DWAXIDMAC_BURST_TRANS_LEN_4.

However, to support hardware with different source/destination burst
transaction length, the aforementioned values shall be configurable
based on dma_slave_config set by client driver.

So, this commit is to allow client driver to configure
- CHx_CTL.SRC_MSIZE via dma_slave_config.src_maxburst
- CHx_CTL.DST_MSIZE via dma_slave_config.dst_maxburst

Signed-off-by: Tan En De <ende.tan@xxxxxxxxxxxxxxxx>
---
v3 -> v4: Update patch after rebase with dmaengine/next
---
 drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c | 18 +++++++++++++++---
 drivers/dma/dw-axi-dmac/dw-axi-dmac.h          |  3 ++-
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
index fffafa86d964..18ce7d64958b 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac-platform.c
@@ -657,7 +657,7 @@ static int dw_axi_dma_set_hw_desc(struct axi_dma_chan *chan,
 	size_t axi_block_ts;
 	size_t block_ts;
 	u32 ctllo, ctlhi;
-	u32 burst_len;
+	u32 burst_len, src_burst_trans_len, dst_burst_trans_len;
 
 	axi_block_ts = chan->chip->dw->hdata->block_size[chan->id];
 
@@ -721,8 +721,20 @@ static int dw_axi_dma_set_hw_desc(struct axi_dma_chan *chan,
 
 	hw_desc->lli->block_ts_lo = cpu_to_le32(block_ts - 1);
 
-	ctllo |= DWAXIDMAC_BURST_TRANS_LEN_4 << CH_CTL_L_DST_MSIZE_POS |
-		 DWAXIDMAC_BURST_TRANS_LEN_4 << CH_CTL_L_SRC_MSIZE_POS;
+	dst_burst_trans_len = chan->config.dst_maxburst ?
+				__ffs(chan->config.dst_maxburst) - 1 :
+				DWAXIDMAC_BURST_TRANS_LEN_4;
+	if (dst_burst_trans_len > DWAXIDMAC_BURST_TRANS_LEN_MAX)
+		return -EINVAL;
+	ctllo |= dst_burst_trans_len << CH_CTL_L_DST_MSIZE_POS;
+
+	src_burst_trans_len = chan->config.src_maxburst ?
+				__ffs(chan->config.src_maxburst) - 1 :
+				DWAXIDMAC_BURST_TRANS_LEN_4;
+	if (src_burst_trans_len > DWAXIDMAC_BURST_TRANS_LEN_MAX)
+		return -EINVAL;
+	ctllo |= src_burst_trans_len << CH_CTL_L_SRC_MSIZE_POS;
+
 	hw_desc->lli->ctl_lo = cpu_to_le32(ctllo);
 
 	set_desc_src_master(hw_desc);
diff --git a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
index b842e6a8d90d..d76d3d88ceb6 100644
--- a/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
+++ b/drivers/dma/dw-axi-dmac/dw-axi-dmac.h
@@ -270,7 +270,8 @@ enum {
 	DWAXIDMAC_BURST_TRANS_LEN_128,
 	DWAXIDMAC_BURST_TRANS_LEN_256,
 	DWAXIDMAC_BURST_TRANS_LEN_512,
-	DWAXIDMAC_BURST_TRANS_LEN_1024
+	DWAXIDMAC_BURST_TRANS_LEN_1024,
+	DWAXIDMAC_BURST_TRANS_LEN_MAX  = DWAXIDMAC_BURST_TRANS_LEN_1024
 };
 
 #define CH_CTL_L_DST_WIDTH_POS		11
-- 
2.34.1