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spi: spi-imx: add DMA support
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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.

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@freescale.com>
Signed-off-by: Robin Gong <b38343@freescale.com>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
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Robin Gong authored and Mark Brown committed Sep 17, 2014
1 parent 7d1311b commit f62cacc
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Showing 2 changed files with 285 additions and 6 deletions.
5 changes: 5 additions & 0 deletions Documentation/devicetree/bindings/spi/fsl-imx-cspi.txt
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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:

Expand All @@ -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";
};
286 changes: 280 additions & 6 deletions drivers/spi/spi-imx.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand All @@ -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"
Expand All @@ -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;
Expand Down Expand Up @@ -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];
};
Expand Down Expand Up @@ -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
Expand All @@ -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)

Expand Down Expand Up @@ -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;

/*
Expand Down Expand Up @@ -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;
}

Expand Down Expand Up @@ -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);
Expand All @@ -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);
Expand Down Expand Up @@ -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);

Expand Down Expand Up @@ -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;
Expand Down

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