From 5147d5bfddc807e990a762aed0e56724afeda663 Mon Sep 17 00:00:00 2001
From: Joy Chakraborty <joychakr@google.com>
Date: Thu, 27 Apr 2023 12:33:10 +0000
Subject: [PATCH 1/2] spi: dw: Add 32 bpw support to SPI DW DMA driver

Add Support for AxSize = 4 bytes configuration from dw dma driver if
n_bytes i.e. number of bytes per write to fifo is 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.
Hence, for bits per word values between 17 and 32 n_bytes should be
equal to 4.

* tested on Baikal-T1 based system with DW SPI-looped back interface
transferring a chunk of data with DFS:8,12,16.

Signed-off-by: Joy Chakraborty <joychakr@google.com
Reviewed-by: Serge Semin <fancer.lancer@gmail.com
Tested-by: Serge Semin <fancer.lancer@gmail.com
Link: https://lore.kernel.org/r/20230427123314.1997152-2-joychakr@google.com
Signed-off-by: Mark Brown <broonie@kernel.org
---
 drivers/spi/spi-dw-dma.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index ababb910b391..c1b42cb59965 100644
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -208,12 +208,16 @@ 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 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)

From d2ae5d42464e990b4d26734c180fbff64233992c Mon Sep 17 00:00:00 2001
From: Joy Chakraborty <joychakr@google.com>
Date: Thu, 27 Apr 2023 12:33:11 +0000
Subject: [PATCH 2/2] spi: dw: Move dw_spi_can_dma()

Move dw_spi_can_dma() implementation below dw_spi_dma_convert_width()
for handing compile dependency in future patches.

* tested on Baikal-T1 based system with DW SPI-looped back interface
transferring a chunk of data with DFS:8,12,16.

Signed-off-by: Joy Chakraborty <joychakr@google.com
Reviewed-by: Serge Semin <fancer.lancer@gmail.com
Tested-by: Serge Semin <fancer.lancer@gmail.com
Link: https://lore.kernel.org/r/20230427123314.1997152-3-joychakr@google.com
Signed-off-by: Mark Brown <broonie@kernel.org
---
 drivers/spi/spi-dw-dma.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/spi/spi-dw-dma.c b/drivers/spi/spi-dw-dma.c
index c1b42cb59965..f19c092920a1 100644
--- a/drivers/spi/spi-dw-dma.c
+++ b/drivers/spi/spi-dw-dma.c
@@ -198,14 +198,6 @@ static irqreturn_t dw_spi_dma_transfer_handler(struct dw_spi *dws)
 	return IRQ_HANDLED;
 }
 
-static bool dw_spi_can_dma(struct spi_controller *master,
-			   struct spi_device *spi, struct spi_transfer *xfer)
-{
-	struct dw_spi *dws = spi_controller_get_devdata(master);
-
-	return xfer->len > dws->fifo_len;
-}
-
 static enum dma_slave_buswidth dw_spi_dma_convert_width(u8 n_bytes)
 {
 	switch (n_bytes) {
@@ -220,6 +212,14 @@ static enum dma_slave_buswidth dw_spi_dma_convert_width(u8 n_bytes)
 	}
 }
 
+static bool dw_spi_can_dma(struct spi_controller *master,
+			   struct spi_device *spi, struct spi_transfer *xfer)
+{
+	struct dw_spi *dws = spi_controller_get_devdata(master);
+
+	return xfer->len > dws->fifo_len;
+}
+
 static int dw_spi_dma_wait(struct dw_spi *dws, unsigned int len, u32 speed)
 {
 	unsigned long long ms;