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Message-ID: <20151215094111.GA11427@shlinux2>
Date: Tue, 15 Dec 2015 17:41:29 +0800
From: Robin Gong <b38343@...escale.com>
To: Anton Bondarenko <anton.bondarenko.sama@...il.com>
CC: <broonie@...nel.org>, <s.hauer@...gutronix.de>,
<linux-kernel@...r.kernel.org>, <linux-spi@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<vladimir_zapolskiy@...tor.com>, <jiada_wang@...tor.com>
Subject: Re: [PATCH v6 8/8] spi: imx: add support for all SPI word width for
DMA
On Tue, Dec 08, 2015 at 07:43:50AM +0100, Anton Bondarenko wrote:
> 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@...il.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) {
Configure dma even in PIO mode for some minimal data transfer case?It's better
to check can_dma here.
> + 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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