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Subject[PATCH 3/4] spi: imx: Chose DMA bits per word transfered
Date
This patch enable to give a parameter to device tree to set the number of bits per word the DMA uses in transfer
In device tree you can specify fsl,spi-dma-bits-per-word = <16>; in the ecspi section

Signed-off-by: Aurelien BOUIN <a.bouin@gmail.com>

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index f8400b2..9690d57 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -110,6 +110,7 @@ struct spi_imx_data {
u32 rxt_wml;
struct completion dma_rx_completion;
struct completion dma_tx_completion;
+ unsigned int dma_bits_per_word;

const struct spi_imx_devtype_data *devtype_data;
int chipselect[0];
@@ -825,6 +826,7 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx,
{
struct dma_slave_config slave_config = {};
int ret;
+ enum dma_slave_buswidth dsb_default = DMA_SLAVE_BUSWIDTH_1_BYTE;

/* use pio mode for i.mx6dl chip TKT238285 */
if (of_machine_is_compatible("fsl,imx6dl"))
@@ -837,10 +839,20 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx,
ret = -EINVAL;
goto err;
}
-
+ switch (spi_imx->dma_bits_per_word) {
+ case 32:
+ dsb_default = DMA_SLAVE_BUSWIDTH_4_BYTES;
+ break;
+ case 16:
+ dsb_default = DMA_SLAVE_BUSWIDTH_2_BYTES;
+ break;
+ default:
+ dsb_default = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ break;
+ }
slave_config.direction = DMA_MEM_TO_DEV;
slave_config.dst_addr = res->start + MXC_CSPITXDATA;
- slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ slave_config.dst_addr_width = dsb_default;
slave_config.dst_maxburst = spi_imx_get_fifosize(spi_imx) / 2;
ret = dmaengine_slave_config(master->dma_tx, &slave_config);
if (ret) {
@@ -858,7 +870,7 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx,

slave_config.direction = DMA_DEV_TO_MEM;
slave_config.src_addr = res->start + MXC_CSPIRXDATA;
- slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ slave_config.src_addr_width = dsb_default;
slave_config.src_maxburst = spi_imx_get_fifosize(spi_imx) / 2;
ret = dmaengine_slave_config(master->dma_rx, &slave_config);
if (ret) {
@@ -1083,7 +1095,7 @@ static int spi_imx_probe(struct platform_device *pdev)
struct spi_master *master;
struct spi_imx_data *spi_imx;
struct resource *res;
- int i, ret, num_cs;
+ int i, ret, num_cs, dma_bits_per_word = 8;

if (!np && !mxc_platform_info) {
dev_err(&pdev->dev, "can't get the platform data\n");
@@ -1138,6 +1150,11 @@ static int spi_imx_probe(struct platform_device *pdev)
spi_imx->bitbang.master->prepare_message = spi_imx_prepare_message;
spi_imx->bitbang.master->unprepare_message = spi_imx_unprepare_message;
spi_imx->bitbang.master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
+ if (of_property_read_u32(np, "fsl,spi-dma-bits-per-word",
+ &dma_bits_per_word))
+ spi_imx->dma_bits_per_word = dma_bits_per_word;
+ else
+ spi_imx->dma_bits_per_word = 8;

init_completion(&spi_imx->xfer_done);

--
1.9.1


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