[PATCH v4 1/2] spi: dw: Add 32 bpw support to DW DMA Controller

[Joy Chakraborty <joychakr@xxxxxxxxxx>]

Add Support for AxSize = 4 bytes configuration from dw dma driver if
n_bytes i.e. number of bytes per write to fifo is 3 or 4.

Number of bytes written to fifo per write is depended on the bits/word
configuration being used which the DW core driver translates to n_bytes.

Signed-off-by: Joy Chakraborty <joychakr@xxxxxxxxxx>
---
 drivers/spi/spi-dw-dma.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index ababb910b391..b3a88bb75907 100644
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -208,12 +208,17 @@ static bool dw_spi_can_dma(struct spi_controller *master,
 
 static enum dma_slave_buswidth dw_spi_dma_convert_width(u8 n_bytes)
 {
-	if (n_bytes == 1)
+	switch (n_bytes) {
+	case 1:
 		return DMA_SLAVE_BUSWIDTH_1_BYTE;
-	else if (n_bytes == 2)
+	case 2:
 		return DMA_SLAVE_BUSWIDTH_2_BYTES;
-
-	return DMA_SLAVE_BUSWIDTH_UNDEFINED;
+	case 3:
+	case 4:
+		return DMA_SLAVE_BUSWIDTH_4_BYTES;
+	default:
+		return DMA_SLAVE_BUSWIDTH_UNDEFINED;
+	}
 }
 
 static int dw_spi_dma_wait(struct dw_spi *dws, unsigned int len, u32 speed)
-- 
2.40.0.348.gf938b09366-goog