Re: [PATCH v6] spi: spi-imx: add DMA support

From: Mark Brown
Date: Mon Sep 15 2014 - 18:40:08 EST

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In reply to: Robin Gong: "[PATCH v6] spi: spi-imx: add DMA support"
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On Thu, Sep 11, 2014 at 09:18:44AM +0800, Robin Gong wrote:
> Enable DMA support on i.mx6. The read speed can increase from 600KB/s
> to 1.2MB/s on i.mx6q. You can disable or enable dma function in dts.
> If not set "dma-names" in dts, spi will use PIO mode. This patch only
> validate on i.mx6, not i.mx5, but encourage ones to apply this patch
> on i.mx5 since they share the same IP.

Adding Maerk (who I had to add to earlier versions of this patch).

>
> Note:
> Sometime, there is a weid data in rxfifo after one full tx/rx
> transfer finish by DMA on i.mx6dl, so we disable dma functhion on
> i.mx6dl.
>
> Signed-off-by: Frank Li <Frank.Li@xxxxxxxxxxxxx>
> Signed-off-by: Robin Gong <b38343@xxxxxxxxxxxxx>
>
> ---
> Change from v5:
> 1. Update binding doc fsl-imx-cspi.txt.
> 2. remove usedma flag set from can_dma interface.
>
> Change from v4:
> 1. Enrich comments.
> 2. Remove the rxfifo workaround. The issue only exist on i.mx6dl, so disable
> dma function in dts.
>
> Change from v3:
> 1. Use spi core framwork to handle dump tx/rx buf
> 2. Add one workaround for weird data in rxfifo when one full transfer done.
>
> Change from v2:
> http://thread.gmane.org/gmane.linux.ports.arm.kernel/291722/focus=294363
> 1. Dma setup only for imx51-ecspi
> 2. Use one small dummy buffer(1 bd size) to templiy store data
> for meanless rx/tx, instead of malloc the actual transfer size.
> 3. Split spi_mx_sdma_transfer to smaller and easily to read.
> 4. Fix some code indent.
> ---
> .../devicetree/bindings/spi/fsl-imx-cspi.txt | 5 +
> drivers/spi/spi-imx.c | 286 ++++++++++++++++++++-
> 2 files changed, 285 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/spi/fsl-imx-cspi.txt b/Documentation/devicetree/bindings/spi/fsl-imx-cspi.txt
> index 4256a6d..aad527b 100644
> --- a/Documentation/devicetree/bindings/spi/fsl-imx-cspi.txt
> +++ b/Documentation/devicetree/bindings/spi/fsl-imx-cspi.txt
> @@ -7,6 +7,9 @@ Required properties:
> - interrupts : Should contain CSPI/eCSPI interrupt
> - fsl,spi-num-chipselects : Contains the number of the chipselect
> - cs-gpios : Specifies the gpio pins to be used for chipselects.
> +- dmas: DMA specifiers for tx and rx dma. See the DMA client binding,
> + Documentation/devicetree/bindings/dma/dma.txt
> +- dma-names: DMA request names should include "tx" and "rx" if present.
>
> Example:
>
> @@ -19,4 +22,6 @@ ecspi@70010000 {
> fsl,spi-num-chipselects = <2>;
> cs-gpios = <&gpio3 24 0>, /* GPIO3_24 */
> <&gpio3 25 0>; /* GPIO3_25 */
> + dmas = <&sdma 3 7 1>, <&sdma 4 7 2>;
> + dma-names = "rx", "tx";
> };
> diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
> index 5daff20..3637847 100644
> --- a/drivers/spi/spi-imx.c
> +++ b/drivers/spi/spi-imx.c
> @@ -21,6 +21,8 @@
> #include <linux/clk.h>
> #include <linux/completion.h>
> #include <linux/delay.h>
> +#include <linux/dmaengine.h>
> +#include <linux/dma-mapping.h>
> #include <linux/err.h>
> #include <linux/gpio.h>
> #include <linux/interrupt.h>
> @@ -37,6 +39,7 @@
> #include <linux/of_device.h>
> #include <linux/of_gpio.h>
>
> +#include <linux/platform_data/dma-imx.h>
> #include <linux/platform_data/spi-imx.h>
>
> #define DRIVER_NAME "spi_imx"
> @@ -51,6 +54,9 @@
> #define MXC_INT_RR (1 << 0) /* Receive data ready interrupt */
> #define MXC_INT_TE (1 << 1) /* Transmit FIFO empty interrupt */
>
> +/* The maximum bytes that a sdma BD can transfer.*/
> +#define MAX_SDMA_BD_BYTES (1 << 15)
> +#define IMX_DMA_TIMEOUT (msecs_to_jiffies(3000))
> struct spi_imx_config {
> unsigned int speed_hz;
> unsigned int bpw;
> @@ -95,6 +101,16 @@ struct spi_imx_data {
> const void *tx_buf;
> unsigned int txfifo; /* number of words pushed in tx FIFO */
>
> + /* DMA */
> + unsigned int dma_is_inited;
> + unsigned int dma_finished;
> + bool usedma;
> + u32 rx_wml;
> + u32 tx_wml;
> + u32 rxt_wml;
> + struct completion dma_rx_completion;
> + struct completion dma_tx_completion;
> +
> const struct spi_imx_devtype_data *devtype_data;
> int chipselect[0];
> };
> @@ -181,9 +197,21 @@ static unsigned int spi_imx_clkdiv_2(unsigned int fin,
> return 7;
> }
>
> +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);
> +
> + if (spi_imx->dma_is_inited && (transfer->len > spi_imx->rx_wml)
> + && (transfer->len > spi_imx->tx_wml))
> + return true;
> + return false;
> +}
> +
> #define MX51_ECSPI_CTRL 0x08
> #define MX51_ECSPI_CTRL_ENABLE (1 << 0)
> #define MX51_ECSPI_CTRL_XCH (1 << 2)
> +#define MX51_ECSPI_CTRL_SMC (1 << 3)
> #define MX51_ECSPI_CTRL_MODE_MASK (0xf << 4)
> #define MX51_ECSPI_CTRL_POSTDIV_OFFSET 8
> #define MX51_ECSPI_CTRL_PREDIV_OFFSET 12
> @@ -201,6 +229,18 @@ static unsigned int spi_imx_clkdiv_2(unsigned int fin,
> #define MX51_ECSPI_INT_TEEN (1 << 0)
> #define MX51_ECSPI_INT_RREN (1 << 3)
>
> +#define MX51_ECSPI_DMA 0x14
> +#define MX51_ECSPI_DMA_TX_WML_OFFSET 0
> +#define MX51_ECSPI_DMA_TX_WML_MASK 0x3F
> +#define MX51_ECSPI_DMA_RX_WML_OFFSET 16
> +#define MX51_ECSPI_DMA_RX_WML_MASK (0x3F << 16)
> +#define MX51_ECSPI_DMA_RXT_WML_OFFSET 24
> +#define MX51_ECSPI_DMA_RXT_WML_MASK (0x3F << 24)
> +
> +#define MX51_ECSPI_DMA_TEDEN_OFFSET 7
> +#define MX51_ECSPI_DMA_RXDEN_OFFSET 23
> +#define MX51_ECSPI_DMA_RXTDEN_OFFSET 31
> +
> #define MX51_ECSPI_STAT 0x18
> #define MX51_ECSPI_STAT_RR (1 << 3)
>
> @@ -257,17 +297,22 @@ static void __maybe_unused mx51_ecspi_intctrl(struct spi_imx_data *spi_imx, int
>
> static void __maybe_unused mx51_ecspi_trigger(struct spi_imx_data *spi_imx)
> {
> - u32 reg;
> -
> - reg = readl(spi_imx->base + MX51_ECSPI_CTRL);
> - reg |= MX51_ECSPI_CTRL_XCH;
> + u32 reg = readl(spi_imx->base + MX51_ECSPI_CTRL);
> +
> + if (!spi_imx->usedma)
> + reg |= MX51_ECSPI_CTRL_XCH;
> + else if (!spi_imx->dma_finished)
> + reg |= MX51_ECSPI_CTRL_SMC;
> + else
> + reg &= ~MX51_ECSPI_CTRL_SMC;
> writel(reg, spi_imx->base + MX51_ECSPI_CTRL);
> }
>
> static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx,
> struct spi_imx_config *config)
> {
> - u32 ctrl = MX51_ECSPI_CTRL_ENABLE, cfg = 0;
> + u32 ctrl = MX51_ECSPI_CTRL_ENABLE, cfg = 0, dma = 0;
> + u32 tx_wml_cfg, rx_wml_cfg, rxt_wml_cfg;
> u32 clk = config->speed_hz, delay;
>
> /*
> @@ -319,6 +364,30 @@ static int __maybe_unused mx51_ecspi_config(struct spi_imx_data *spi_imx,
> else /* SCLK is _very_ slow */
> usleep_range(delay, delay + 10);
>
> + /*
> + * Configure the DMA register: setup the watermark
> + * and enable DMA request.
> + */
> + if (spi_imx->dma_is_inited) {
> + dma = readl(spi_imx->base + MX51_ECSPI_DMA);
> +
> + spi_imx->tx_wml = spi_imx_get_fifosize(spi_imx) / 2;
> + spi_imx->rx_wml = spi_imx_get_fifosize(spi_imx) / 2;
> + spi_imx->rxt_wml = spi_imx_get_fifosize(spi_imx) / 2;
> + rx_wml_cfg = spi_imx->rx_wml << MX51_ECSPI_DMA_RX_WML_OFFSET;
> + tx_wml_cfg = spi_imx->tx_wml << MX51_ECSPI_DMA_TX_WML_OFFSET;
> + rxt_wml_cfg = spi_imx->rxt_wml << MX51_ECSPI_DMA_RXT_WML_OFFSET;
> + dma = (dma & ~MX51_ECSPI_DMA_TX_WML_MASK
> + & ~MX51_ECSPI_DMA_RX_WML_MASK
> + & ~MX51_ECSPI_DMA_RXT_WML_MASK)
> + | rx_wml_cfg | tx_wml_cfg | rxt_wml_cfg
> + |(1 << MX51_ECSPI_DMA_TEDEN_OFFSET)
> + |(1 << MX51_ECSPI_DMA_RXDEN_OFFSET)
> + |(1 << MX51_ECSPI_DMA_RXTDEN_OFFSET);
> +
> + writel(dma, spi_imx->base + MX51_ECSPI_DMA);
> + }
> +
> return 0;
> }
>
> @@ -730,7 +799,186 @@ static int spi_imx_setupxfer(struct spi_device *spi,
> return 0;
> }
>
> -static int spi_imx_transfer(struct spi_device *spi,
> +static void spi_imx_sdma_exit(struct spi_imx_data *spi_imx)
> +{
> + struct spi_master *master = spi_imx->bitbang.master;
> +
> + if (master->dma_rx) {
> + dma_release_channel(master->dma_rx);
> + master->dma_rx = NULL;
> + }
> +
> + if (master->dma_tx) {
> + dma_release_channel(master->dma_tx);
> + master->dma_tx = NULL;
> + }
> +
> + spi_imx->dma_is_inited = 0;
> +}
> +
> +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;
> +
> + /* Prepare for TX DMA: */
> + master->dma_tx = dma_request_slave_channel(dev, "tx");
> + if (!master->dma_tx) {
> + dev_err(dev, "cannot get the TX DMA channel!\n");
> + ret = -EINVAL;
> + 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_get_fifosize(spi_imx) / 2;
> + 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) {
> + dev_dbg(dev, "cannot get the DMA channel.\n");
> + ret = -EINVAL;
> + 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_get_fifosize(spi_imx) / 2;
> + 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->dma_is_inited = 1;
> +
> + return 0;
> +err:
> + spi_imx_sdma_exit(spi_imx);
> + return ret;
> +}
> +
> +static void spi_imx_dma_rx_callback(void *cookie)
> +{
> + struct spi_imx_data *spi_imx = (struct spi_imx_data *)cookie;
> +
> + complete(&spi_imx->dma_rx_completion);
> +}
> +
> +static void spi_imx_dma_tx_callback(void *cookie)
> +{
> + struct spi_imx_data *spi_imx = (struct spi_imx_data *)cookie;
> +
> + complete(&spi_imx->dma_tx_completion);
> +}
> +
> +static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx,
> + struct spi_transfer *transfer)
> +{
> + struct dma_async_tx_descriptor *desc_tx = NULL, *desc_rx = NULL;
> + int ret;
> + u32 dma;
> + int left;
> + struct spi_master *master = spi_imx->bitbang.master;
> + struct sg_table *tx = &transfer->tx_sg, *rx = &transfer->rx_sg;
> +
> + if (tx) {
> + desc_tx = dmaengine_prep_slave_sg(master->dma_tx,
> + tx->sgl, tx->nents, DMA_TO_DEVICE,
> + DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> + if (!desc_tx)
> + goto no_dma;
> +
> + desc_tx->callback = spi_imx_dma_tx_callback;
> + desc_tx->callback_param = (void *)spi_imx;
> + dmaengine_submit(desc_tx);
> + }
> +
> + if (rx) {
> + desc_rx = dmaengine_prep_slave_sg(master->dma_rx,
> + rx->sgl, rx->nents, DMA_FROM_DEVICE,
> + DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> + if (!desc_rx)
> + goto no_dma;
> +
> + desc_rx->callback = spi_imx_dma_rx_callback;
> + desc_rx->callback_param = (void *)spi_imx;
> + dmaengine_submit(desc_rx);
> + }
> +
> + reinit_completion(&spi_imx->dma_rx_completion);
> + reinit_completion(&spi_imx->dma_tx_completion);
> +
> + /* Trigger the cspi module. */
> + spi_imx->dma_finished = 0;
> +
> + dma = readl(spi_imx->base + MX51_ECSPI_DMA);
> + dma = dma & (~MX51_ECSPI_DMA_RXT_WML_MASK);
> + /* Change RX_DMA_LENGTH trigger dma fetch tail data */
> + left = transfer->len % spi_imx->rxt_wml;
> + if (left)
> + writel(dma | (left << MX51_ECSPI_DMA_RXT_WML_OFFSET),
> + spi_imx->base + MX51_ECSPI_DMA);
> + spi_imx->devtype_data->trigger(spi_imx);
> +
> + dma_async_issue_pending(master->dma_tx);
> + dma_async_issue_pending(master->dma_rx);
> + /* Wait SDMA to finish the data transfer.*/
> + ret = wait_for_completion_timeout(&spi_imx->dma_tx_completion,
> + IMX_DMA_TIMEOUT);
> + if (!ret) {
> + pr_warn("%s %s: I/O Error in DMA TX\n",
> + dev_driver_string(&master->dev),
> + dev_name(&master->dev));
> + dmaengine_terminate_all(master->dma_tx);
> + } else {
> + ret = wait_for_completion_timeout(&spi_imx->dma_rx_completion,
> + IMX_DMA_TIMEOUT);
> + if (!ret) {
> + pr_warn("%s %s: I/O Error in DMA RX\n",
> + dev_driver_string(&master->dev),
> + dev_name(&master->dev));
> + spi_imx->devtype_data->reset(spi_imx);
> + dmaengine_terminate_all(master->dma_rx);
> + }
> + writel(dma |
> + spi_imx->rxt_wml << MX51_ECSPI_DMA_RXT_WML_OFFSET,
> + spi_imx->base + MX51_ECSPI_DMA);
> + }
> +
> + spi_imx->dma_finished = 1;
> + spi_imx->devtype_data->trigger(spi_imx);
> +
> + if (!ret)
> + ret = -ETIMEDOUT;
> + else if (ret > 0)
> + ret = transfer->len;
> +
> + return ret;
> +
> +no_dma:
> + pr_warn_once("%s %s: DMA not available, falling back to PIO\n",
> + dev_driver_string(&master->dev),
> + dev_name(&master->dev));
> + return -EAGAIN;
> +}
> +
> +static int spi_imx_pio_transfer(struct spi_device *spi,
> struct spi_transfer *transfer)
> {
> struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
> @@ -751,6 +999,24 @@ static int spi_imx_transfer(struct spi_device *spi,
> return transfer->len;
> }
>
> +static int spi_imx_transfer(struct spi_device *spi,
> + struct spi_transfer *transfer)
> +{
> + int ret;
> + struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
> +
> + if (spi_imx->bitbang.master->can_dma &&
> + spi_imx_can_dma(spi_imx->bitbang.master, spi, transfer)) {
> + spi_imx->usedma = true;
> + ret = spi_imx_dma_transfer(spi_imx, transfer);
> + if (ret != -EAGAIN)
> + return ret;
> + }
> + spi_imx->usedma = false;
> +
> + return spi_imx_pio_transfer(spi, transfer);
> +}
> +
> static int spi_imx_setup(struct spi_device *spi)
> {
> struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
> @@ -911,6 +1177,13 @@ static int spi_imx_probe(struct platform_device *pdev)
> goto out_put_per;
>
> spi_imx->spi_clk = clk_get_rate(spi_imx->clk_per);
> + /*
> + * 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))
> + dev_err(&pdev->dev, "dma setup error,use pio instead\n");
>
> spi_imx->devtype_data->reset(spi_imx);
>
> @@ -949,6 +1222,7 @@ static int spi_imx_remove(struct platform_device *pdev)
> writel(0, spi_imx->base + MXC_CSPICTRL);
> clk_unprepare(spi_imx->clk_ipg);
> clk_unprepare(spi_imx->clk_per);
> + spi_imx_sdma_exit(spi_imx);
> spi_master_put(master);
>
> return 0;
> --
> 1.9.1
>
>

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Next message: Shuah Khan: "[PATCH 0/7] kselftest new exit codes and test changes to use them"
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In reply to: Robin Gong: "[PATCH v6] spi: spi-imx: add DMA support"
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