spi: dw: DW SPI DMA Driver updates

Merge series from Joy Chakraborty <joychakr@google.com>:

This Patch series adds support for 32 bits per word trasfers using DMA
and some defensive checks around dma controller capabilities.

drivers/spi/spi-dw-dma.c

@@ -198,6 +198,20 @@ static irqreturn_t dw_spi_dma_transfer_handler(struct dw_spi *dws)
 	return IRQ_HANDLED;
 }
 
+static enum dma_slave_buswidth dw_spi_dma_convert_width(u8 n_bytes)
+{
+	switch (n_bytes) {
+	case 1:
+		return DMA_SLAVE_BUSWIDTH_1_BYTE;
+	case 2:
+		return DMA_SLAVE_BUSWIDTH_2_BYTES;
+	case 4:
+		return DMA_SLAVE_BUSWIDTH_4_BYTES;
+	default:
+		return DMA_SLAVE_BUSWIDTH_UNDEFINED;
+	}
+}
+
 static bool dw_spi_can_dma(struct spi_controller *master,
 			   struct spi_device *spi, struct spi_transfer *xfer)
 {
@@ -206,16 +220,6 @@ static bool dw_spi_can_dma(struct spi_controller *master,
 	return xfer->len > dws->fifo_len;
 }
 
-static enum dma_slave_buswidth dw_spi_dma_convert_width(u8 n_bytes)
-{
-	if (n_bytes == 1)
-		return DMA_SLAVE_BUSWIDTH_1_BYTE;
-	else if (n_bytes == 2)
-		return DMA_SLAVE_BUSWIDTH_2_BYTES;
-
-	return DMA_SLAVE_BUSWIDTH_UNDEFINED;
-}
-
 static int dw_spi_dma_wait(struct dw_spi *dws, unsigned int len, u32 speed)
 {
 	unsigned long long ms;