[PATCH v6 8/8] spi: imx: add support for all SPI word width for DMA
Anton Bondarenko
anton.bondarenko.sama at gmail.com
Mon Dec 7 22:43:50 PST 2015
DMA transfer for SPI was limited to up to 8 bits word size until now.
Sync in SPI burst size and DMA bus width is necessary to correctly
support 16 and 32 BPW.
Signed-off-by: Anton Bondarenko <anton.bondarenko.sama at gmail.com>
---
drivers/spi/spi-imx.c | 121 +++++++++++++++++++++++++++++++++++++++-----------
1 file changed, 95 insertions(+), 26 deletions(-)
diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index d74d809..750001c 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -88,11 +88,15 @@ struct spi_imx_data {
struct completion xfer_done;
void __iomem *base;
+ unsigned long base_phys;
+
struct clk *clk_per;
struct clk *clk_ipg;
unsigned long spi_clk;
unsigned int spi_bus_clk;
+ unsigned int bytes_per_word;
+
unsigned int count;
void (*tx)(struct spi_imx_data *);
void (*rx)(struct spi_imx_data *);
@@ -199,13 +203,32 @@ static unsigned int spi_imx_clkdiv_2(unsigned int fin,
return 7;
}
+static int spi_imx_get_bytes_per_word(const int bpw)
+{
+ return DIV_ROUND_UP(bpw, BITS_PER_BYTE);
+}
+
static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
struct spi_transfer *transfer)
{
struct spi_imx_data *spi_imx = spi_master_get_devdata(master);
+ unsigned int bpw = transfer->bits_per_word;
+
+ if (!bpw)
+ bpw = spi->bits_per_word;
- if (spi_imx->dma_is_inited && transfer->len >= spi_imx->wml &&
- (transfer->len % spi_imx->wml) == 0)
+ bpw = spi_imx_get_bytes_per_word(bpw);
+
+ /*
+ * We need to use SPI word size in calculation to decide
+ * if we want to go with DMA or PIO mode. Just a short example:
+ * We need to transfer 24 SPI words with BPW == 32. This will take
+ * 24 PIO writes to FIFO (and same for reads). But transfer->len will
+ * be 24*4=96 bytes. WML is 32 SPI words. The decision will be incorrect
+ * if we do not take into account SPI bits per word.
+ */
+ if (spi_imx->dma_is_inited && transfer->len >= (spi_imx->wml * bpw) &&
+ (transfer->len % (spi_imx->wml * bpw)) == 0)
return true;
return false;
}
@@ -785,11 +808,60 @@ static irqreturn_t spi_imx_isr(int irq, void *dev_id)
return IRQ_HANDLED;
}
+static int spi_imx_sdma_configure(struct spi_master *master)
+{
+ int ret;
+ enum dma_slave_buswidth dsb_default = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ struct dma_slave_config slave_config = {};
+ struct spi_imx_data *spi_imx = spi_master_get_devdata(master);
+
+ switch (spi_imx->bytes_per_word) {
+ case 4:
+ dsb_default = DMA_SLAVE_BUSWIDTH_4_BYTES;
+ break;
+ case 2:
+ dsb_default = DMA_SLAVE_BUSWIDTH_2_BYTES;
+ break;
+ case 1:
+ dsb_default = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ break;
+ default:
+ pr_err("Not supported word size %d\n", spi_imx->bytes_per_word);
+ ret = -EINVAL;
+ goto err;
+ }
+
+ slave_config.direction = DMA_MEM_TO_DEV;
+ slave_config.dst_addr = spi_imx->base_phys + MXC_CSPITXDATA;
+ slave_config.dst_addr_width = dsb_default;
+ slave_config.dst_maxburst = spi_imx->wml;
+ ret = dmaengine_slave_config(master->dma_tx, &slave_config);
+ if (ret) {
+ pr_err("error in TX dma configuration.\n");
+ goto err;
+ }
+
+ memset(&slave_config, 0, sizeof(slave_config));
+
+ slave_config.direction = DMA_DEV_TO_MEM;
+ slave_config.src_addr = spi_imx->base_phys + MXC_CSPIRXDATA;
+ slave_config.src_addr_width = dsb_default;
+ slave_config.src_maxburst = spi_imx->wml;
+ ret = dmaengine_slave_config(master->dma_rx, &slave_config);
+ if (ret)
+ pr_err("error in RX dma configuration.\n");
+
+err:
+ return ret;
+}
+
static int spi_imx_setupxfer(struct spi_device *spi,
struct spi_transfer *t)
{
struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
struct spi_imx_config config;
+ unsigned int new_bytes_per_word;
+ int ret = 0;
config.bpw = t ? t->bits_per_word : spi->bits_per_word;
config.speed_hz = t ? t->speed_hz : spi->max_speed_hz;
@@ -813,9 +885,19 @@ static int spi_imx_setupxfer(struct spi_device *spi,
spi_imx->tx = spi_imx_buf_tx_u32;
}
- spi_imx->devtype_data->config(spi_imx, &config);
+ new_bytes_per_word = spi_imx_get_bytes_per_word(config.bpw);
+ if (spi_imx->dma_is_inited &&
+ spi_imx->bytes_per_word != new_bytes_per_word) {
+ spi_imx->bytes_per_word = new_bytes_per_word;
+ ret = spi_imx_sdma_configure(spi->master);
+ if (ret != 0)
+ pr_err("Can't configure SDMA, error %d\n", ret);
+ }
- return 0;
+ if (!ret)
+ ret = spi_imx->devtype_data->config(spi_imx, &config);
+
+ return ret;
}
static void spi_imx_sdma_exit(struct spi_imx_data *spi_imx)
@@ -839,7 +921,6 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx,
struct spi_master *master,
const struct resource *res)
{
- struct dma_slave_config slave_config = {};
int ret;
/* use pio mode for i.mx6dl chip TKT238285 */
@@ -857,16 +938,6 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx,
goto err;
}
- 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_maxburst = spi_imx->wml;
- ret = dmaengine_slave_config(master->dma_tx, &slave_config);
- if (ret) {
- dev_err(dev, "error in TX dma configuration.\n");
- goto err;
- }
-
/* Prepare for RX : */
master->dma_rx = dma_request_slave_channel_reason(dev, "rx");
if (IS_ERR(master->dma_rx)) {
@@ -876,22 +947,20 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx,
goto err;
}
- 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_maxburst = spi_imx->wml;
- ret = dmaengine_slave_config(master->dma_rx, &slave_config);
- if (ret) {
- dev_err(dev, "error in RX dma configuration.\n");
- goto err;
- }
-
init_completion(&spi_imx->dma_rx_completion);
init_completion(&spi_imx->dma_tx_completion);
master->can_dma = spi_imx_can_dma;
master->max_dma_len = MAX_SDMA_BD_BYTES;
spi_imx->bitbang.master->flags = SPI_MASTER_MUST_RX |
SPI_MASTER_MUST_TX;
+ spi_imx->bytes_per_word = 1;
+ spi_imx->base_phys = res->start;
+ ret = spi_imx_sdma_configure(master);
+ if (ret) {
+ dev_info(dev, "cannot get setup DMA.\n");
+ goto err;
+ }
+
spi_imx->dma_is_inited = 1;
return 0;
@@ -993,7 +1062,7 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx,
dmaengine_terminate_all(master->dma_rx);
} else {
transfer_timeout = spi_imx_calculate_timeout(spi_imx,
- spi_imx->wml);
+ spi_imx->bytes_per_word * spi_imx->wml);
timeout = wait_for_completion_timeout(
&spi_imx->dma_rx_completion, transfer_timeout);
if (!timeout) {
--
2.6.3
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