Subject: [PATCH v3 3/7] spi: imx: add support for all SPI word width for DMA transfer

From: [email-masked] (Anton Bondarenko)
Date: Sat, 14 Nov 2015 11:08:22 +0100

On 01.11.2015 15:41, Anton Bondarenko wrote:
> From: Anton Bondarenko <[email-masked]>
>
> 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 other BPW supported by HW.
>
> Signed-off-by: Anton Bondarenko <[email-masked]>
> ---
>   drivers/spi/spi-imx.c | 133 ++++++++++++++++++++++++++++++++++++++------------
>   1 file changed, 102 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
> index 9b80c7f..06f52c3 100644
> --- a/drivers/spi/spi-imx.c
> +++ b/drivers/spi/spi-imx.c
> @@ -89,11 +89,15 @@ 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 *);
> @@ -195,12 +199,31 @@ 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)
> +	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))
>   		return true;
>   	return false;
>   }
> @@ -764,11 +787,60 @@ 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;
> @@ -792,9 +864,19 @@ 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);
> +	}
> +
> +	if (!ret)
> +		ret = spi_imx->devtype_data->config(spi_imx, &config);
>
> -	return 0;
> +	return ret;
>   }
>
>   static void spi_imx_sdma_exit(struct spi_imx_data *spi_imx)
> @@ -815,10 +897,8 @@ static void spi_imx_sdma_exit(struct spi_imx_data *spi_imx)
>   }
>
>   static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx,
> -			     struct spi_master *master,
> -			     const struct resource *res)
> +			     struct spi_master *master)
>   {
> -	struct dma_slave_config slave_config = {};
>   	int ret;
>
>   	/* use pio mode for i.mx6dl chip TKT238285 */
> @@ -835,16 +915,6 @@ 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(dev, "rx");
>   	if (!master->dma_rx) {
> @@ -853,22 +923,19 @@ 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;
> +	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;
> @@ -925,7 +992,8 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx,
>   	int ret;
>   	unsigned long timeout;
>   	unsigned long transfer_timeout;
> -	const int left = transfer->len % spi_imx->wml;
> +	const int left = transfer->len %
> +			 (spi_imx->wml * spi_imx->bytes_per_word);
>   	struct spi_master *master = spi_imx->bitbang.master;
>   	struct sg_table *tx = &transfer->tx_sg, *rx = &transfer->rx_sg;
>
> @@ -998,7 +1066,7 @@ 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) {
> @@ -1016,7 +1084,9 @@ static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx,
>   					    DMA_FROM_DEVICE);
>
>   			spi_imx->rx_buf = pio_buffer;
> -			spi_imx->txfifo = left;
> +			spi_imx->txfifo = DIV_ROUND_UP(left,
> +						       spi_imx->bytes_per_word);
> +
>   			reinit_completion(&spi_imx->xfer_done);
>
>   			spi_imx->devtype_data->intctrl(spi_imx, MXC_INT_TCEN);
> @@ -1224,6 +1294,7 @@ static int spi_imx_probe(struct platform_device *pdev)
>   		ret = PTR_ERR(spi_imx->base);
>   		goto out_master_put;
>   	}
> +	spi_imx->base_phys = res->start;
>
>   	irq = platform_get_irq(pdev, 0);
>   	if (irq < 0) {
> @@ -1263,8 +1334,8 @@ static int spi_imx_probe(struct platform_device *pdev)
>   	 * Only validated on i.mx6 now, can remove the constrain if validated on
>   	 * other chips.
>   	 */
> -	if (spi_imx->devtype_data == &imx51_ecspi_devtype_data
> -	    && spi_imx_sdma_init(&pdev->dev, spi_imx, master, res))
> +	if (spi_imx->devtype_data == &imx51_ecspi_devtype_data &&
> +	    spi_imx_sdma_init(&pdev->dev, spi_imx, master))
>   		dev_err(&pdev->dev, "dma setup error,use pio instead\n");
>
>   	spi_imx->devtype_data->reset(spi_imx);
>

Does anyone has other comments regarding this commit?

Regards, Anton