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[v2,linux-next,3/3] spi: imx: Add support for SPI Slave mode

Message ID 1496222398-3192-4-git-send-email-jiada_wang@mentor.com (mailing list archive)
State New, archived
Headers show

Commit Message

Wang, Jiada May 31, 2017, 9:19 a.m. UTC
From: Jiada Wang <jiada_wang@mentor.com>

Previously i.MX SPI controller only works in Master mode.
This patch adds support to i.MX51, i.MX53 and i.MX6 ECSPI
controller to work also in Slave mode.

Currently SPI Slave mode support patch has the following limitations:
1. The stale data in RXFIFO will be dropped when the Slave does any new
   transfer.
2. One transfer can be finished only after all transfer->len data been
   transferred to master device
3. Slave device only accepts transfer->len data. Any data longer than this
   from master device will be dropped. Any data shorter than this from
   master will cause SPI to stuck due to mentioned HW limitation 2.
4. Only PIO transfer is supported in Slave mode.

Following HW limitation applies:
1.  ECSPI has a HW issue when works in Slave mode, after 64
    words written to TXFIFO, even TXFIFO becomes empty,
    ECSPI_TXDATA keeps shift out the last word data,
    so we have to disable ECSPI when in slave mode after the
    transfer completes
2.  Due to Freescale errata ERR003775 "eCSPI: Burst completion by Chip
    Select (SS) signal in Slave mode is not functional" burst size must
    be set exactly to the size of the transfer. This limit SPI transaction
    with maximum 2^12 bits. This errata affects i.MX53 and i.MX6 ECSPI
    controllers.

Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
---
 drivers/spi/spi-imx.c | 227 +++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 195 insertions(+), 32 deletions(-)

Comments

s.hauer@pengutronix.de May 31, 2017, 12:10 p.m. UTC | #1
On Wed, May 31, 2017 at 02:19:58AM -0700, jiada_wang@mentor.com wrote:
> From: Jiada Wang <jiada_wang@mentor.com>
> 
> Previously i.MX SPI controller only works in Master mode.
> This patch adds support to i.MX51, i.MX53 and i.MX6 ECSPI
> controller to work also in Slave mode.
> 
> Currently SPI Slave mode support patch has the following limitations:
> 1. The stale data in RXFIFO will be dropped when the Slave does any new
>    transfer.
> 2. One transfer can be finished only after all transfer->len data been
>    transferred to master device
> 3. Slave device only accepts transfer->len data. Any data longer than this
>    from master device will be dropped. Any data shorter than this from
>    master will cause SPI to stuck due to mentioned HW limitation 2.
> 4. Only PIO transfer is supported in Slave mode.
> 
> Following HW limitation applies:
> 1.  ECSPI has a HW issue when works in Slave mode, after 64
>     words written to TXFIFO, even TXFIFO becomes empty,
>     ECSPI_TXDATA keeps shift out the last word data,
>     so we have to disable ECSPI when in slave mode after the
>     transfer completes
> 2.  Due to Freescale errata ERR003775 "eCSPI: Burst completion by Chip
>     Select (SS) signal in Slave mode is not functional" burst size must
>     be set exactly to the size of the transfer. This limit SPI transaction
>     with maximum 2^12 bits. This errata affects i.MX53 and i.MX6 ECSPI
>     controllers.
> 
> Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
> ---
>  drivers/spi/spi-imx.c | 227 +++++++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 195 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
> index 765856c..a227a30 100644
> --- a/drivers/spi/spi-imx.c
> +++ b/drivers/spi/spi-imx.c
> @@ -53,9 +53,13 @@
>  /* generic defines to abstract from the different register layouts */
>  #define MXC_INT_RR	(1 << 0) /* Receive data ready interrupt */
>  #define MXC_INT_TE	(1 << 1) /* Transmit FIFO empty interrupt */
> +#define MXC_INT_RDR	BIT(4) /* Receive date threshold interrupt */
>  
>  /* The maximum  bytes that a sdma BD can transfer.*/
>  #define MAX_SDMA_BD_BYTES  (1 << 15)
> +/* The maximum bytes that IMX53_ECSPI can transfer in slave mode.*/
> +#define MX53_MAX_TRANSFER_BYTES		512
> +
>  struct spi_imx_config {
>  	unsigned int speed_hz;
>  	unsigned int bpw;
> @@ -79,6 +83,7 @@ struct spi_imx_devtype_data {
>  	void (*trigger)(struct spi_imx_data *);
>  	int (*rx_available)(struct spi_imx_data *);
>  	void (*reset)(struct spi_imx_data *);
> +	void (*disable)(struct spi_imx_data *);
>  	enum spi_imx_devtype devtype;
>  };
>  
> @@ -105,6 +110,11 @@ struct spi_imx_data {
>  	const void *tx_buf;
>  	unsigned int txfifo; /* number of words pushed in tx FIFO */
>  
> +	/* Slave mode */
> +	bool slave_mode;
> +	bool slave_aborted;
> +	unsigned int slave_burst;
> +
>  	/* DMA */
>  	bool usedma;
>  	u32 wml;
> @@ -157,6 +167,17 @@ static inline bool spi_imx_has_dmamode(struct spi_imx_data *d)
>  	}
>  }
>  
> +static inline bool spi_imx_has_slavemode(const struct spi_imx_devtype_data *d)
> +{
> +	switch (d->devtype) {
> +	case IMX51_ECSPI:
> +	case IMX53_ECSPI:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}

Add a new boolean flag to struct spi_imx_devtype_data instead.


> +
>  #define MXC_SPI_BUF_RX(type)						\
>  static void spi_imx_buf_rx_##type(struct spi_imx_data *spi_imx)		\
>  {									\
> @@ -287,6 +308,7 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
>  #define MX51_ECSPI_INT		0x10
>  #define MX51_ECSPI_INT_TEEN		(1 <<  0)
>  #define MX51_ECSPI_INT_RREN		(1 <<  3)
> +#define MX51_ECSPI_INT_RDREN		(1 <<  4)
>  
>  #define MX51_ECSPI_DMA      0x14
>  #define MX51_ECSPI_DMA_TX_WML(wml)	((wml) & 0x3f)
> @@ -303,6 +325,51 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
>  #define MX51_ECSPI_TESTREG	0x20
>  #define MX51_ECSPI_TESTREG_LBC	BIT(31)
>  
> +static void mx53_ecspi_rx_slave(struct spi_imx_data *spi_imx)
> +{
> +	u32 val = be32_to_cpu(readl(spi_imx->base + MXC_CSPIRXDATA));
> +
> +	if (spi_imx->rx_buf) {
> +		int shift = spi_imx->slave_burst % sizeof(val);
> +
> +		if (shift) {
> +			memcpy(spi_imx->rx_buf,
> +			       ((u8 *)&val) + sizeof(val) - shift, shift);
> +		} else {
> +			*((u32 *)spi_imx->rx_buf) = val;
> +			shift = sizeof(val);
> +		}
> +
> +		spi_imx->rx_buf += shift;
> +		spi_imx->slave_burst -= shift;
> +	}
> +}
> +
> +static void mx53_ecspi_tx_slave(struct spi_imx_data *spi_imx)
> +{
> +	u32 val = 0;
> +	int shift = spi_imx->count % sizeof(val);
> +
> +	if (spi_imx->tx_buf) {
> +		if (shift) {
> +			memcpy(((u8 *)&val) + sizeof(val) - shift,
> +			       spi_imx->tx_buf, shift);
> +		} else {
> +			val = *((u32 *)spi_imx->tx_buf);
> +			shift = sizeof(val);
> +		}
> +		val = cpu_to_be32(val);
> +		spi_imx->tx_buf += shift;
> +	}
> +
> +	if (!shift)
> +		shift = sizeof(val);

A better name for 'shift' is n_bytes. Its value should be calculated
before the if (spi_imx->tx_buf) block. Then you can use memcpy for the
four byte case aswell.


But anyway, have you tested this function for anything with
spi_imx->count % sizeof(val) != 0? In this case you have to put the fill
the FIFO only partly somewhere. I would assume you have to do this at
the end of the transfer, but you do this at the beginning. Can this
work?

> +
> +	spi_imx->count -= shift;
> +
> +	writel(val, spi_imx->base + MXC_CSPITXDATA);
> +}
> +
>  /* MX51 eCSPI */
>  static unsigned int mx51_ecspi_clkdiv(struct spi_imx_data *spi_imx,
>  				      unsigned int fspi, unsigned int *fres)
> @@ -352,6 +419,9 @@ static void mx51_ecspi_intctrl(struct spi_imx_data *spi_imx, int enable)
>  	if (enable & MXC_INT_RR)
>  		val |= MX51_ECSPI_INT_RREN;
>  
> +	if (enable & MXC_INT_RDR)
> +		val |= MX51_ECSPI_INT_RDREN;
> +
>  	writel(val, spi_imx->base + MX51_ECSPI_INT);
>  }
>  
> @@ -364,6 +434,15 @@ static void mx51_ecspi_trigger(struct spi_imx_data *spi_imx)
>  	writel(reg, spi_imx->base + MX51_ECSPI_CTRL);
>  }
>  
> +static void __maybe_unused mx51_ecspi_disable(struct spi_imx_data *spi_imx)

I don't see how this function may end up unused.

> +{
> +	u32 ctrl;
> +
> +	ctrl = readl(spi_imx->base + MX51_ECSPI_CTRL);
> +	ctrl &= ~MX51_ECSPI_CTRL_ENABLE;
> +	writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
> +}
> +
>  static int mx51_ecspi_config(struct spi_device *spi,
>  			     struct spi_imx_config *config)
>  {
> @@ -372,14 +451,11 @@ static int mx51_ecspi_config(struct spi_device *spi,
>  	u32 clk = config->speed_hz, delay, reg;
>  	u32 cfg = readl(spi_imx->base + MX51_ECSPI_CONFIG);
>  
> -	/*
> -	 * The hardware seems to have a race condition when changing modes. The
> -	 * current assumption is that the selection of the channel arrives
> -	 * earlier in the hardware than the mode bits when they are written at
> -	 * the same time.
> -	 * So set master mode for all channels as we do not support slave mode.
> -	 */
> -	ctrl |= MX51_ECSPI_CTRL_MODE_MASK;
> +	/* set Master or Slave mode */
> +	if (spi_imx->slave_mode)
> +		ctrl &= ~MX51_ECSPI_CTRL_MODE_MASK;
> +	else
> +		ctrl |= MX51_ECSPI_CTRL_MODE_MASK;
>  
>  	/*
>  	 * Enable SPI_RDY handling (falling edge/level triggered).
> @@ -394,9 +470,21 @@ static int mx51_ecspi_config(struct spi_device *spi,
>  	/* set chip select to use */
>  	ctrl |= MX51_ECSPI_CTRL_CS(spi->chip_select);
>  
> -	ctrl |= (config->bpw - 1) << MX51_ECSPI_CTRL_BL_OFFSET;
> +	if (spi_imx->slave_mode && is_imx53_ecspi(spi_imx))
> +		ctrl |= (spi_imx->slave_burst * 8 - 1)
> +			<< MX51_ECSPI_CTRL_BL_OFFSET;
> +	else
> +		ctrl |= (config->bpw - 1) << MX51_ECSPI_CTRL_BL_OFFSET;
>  
> -	cfg |= MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);
> +	/*
> +	 * eCSPI burst completion by Chip Select signal in Slave mode
> +	 * is not functional for imx53 Soc, config SPI burst completed when
> +	 * BURST_LENGTH + 1 bits are received
> +	 */
> +	if (spi_imx->slave_mode && is_imx53_ecspi(spi_imx))
> +		cfg &= ~MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);
> +	else
> +		cfg |= MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);
>  
>  	if (spi->mode & SPI_CPHA)
>  		cfg |= MX51_ECSPI_CONFIG_SCLKPHA(spi->chip_select);
> @@ -775,6 +863,7 @@ static struct spi_imx_devtype_data imx51_ecspi_devtype_data = {
>  	.trigger = mx51_ecspi_trigger,
>  	.rx_available = mx51_ecspi_rx_available,
>  	.reset = mx51_ecspi_reset,
> +	.disable = mx51_ecspi_disable,
>  	.devtype = IMX51_ECSPI,
>  };
>  
> @@ -784,6 +873,7 @@ static struct spi_imx_devtype_data imx53_ecspi_devtype_data = {
>  	.trigger = mx51_ecspi_trigger,
>  	.rx_available = mx51_ecspi_rx_available,
>  	.reset = mx51_ecspi_reset,
> +	.disable = mx51_ecspi_disable,
>  	.devtype = IMX53_ECSPI,
>  };
>  
> @@ -846,14 +936,16 @@ static void spi_imx_push(struct spi_imx_data *spi_imx)
>  		spi_imx->txfifo++;
>  	}
>  
> -	spi_imx->devtype_data->trigger(spi_imx);
> +	if (!spi_imx->slave_mode)
> +		spi_imx->devtype_data->trigger(spi_imx);
>  }
>  
>  static irqreturn_t spi_imx_isr(int irq, void *dev_id)
>  {
>  	struct spi_imx_data *spi_imx = dev_id;
>  
> -	while (spi_imx->devtype_data->rx_available(spi_imx)) {
> +	while (spi_imx->txfifo &&
> +	       spi_imx->devtype_data->rx_available(spi_imx)) {
>  		spi_imx->rx(spi_imx);
>  		spi_imx->txfifo--;
>  	}
> @@ -952,7 +1044,8 @@ static int spi_imx_setupxfer(struct spi_device *spi,
>  		spi_imx->tx = spi_imx_buf_tx_u32;
>  	}
>  
> -	if (spi_imx_can_dma(spi_imx->bitbang.master, spi, t))
> +	if (!spi_imx->slave_mode &&
> +	    spi_imx_can_dma(spi_imx->bitbang.master, spi, t))
>  		spi_imx->usedma = 1;

So in spi_imx_can_dma() you may return true for a slave mode transfer
and here we end up doing PIO for the same transfer. That doesn't look
correct. You should move the test for slave mode into spi_imx_can_dma().

>  	else
>  		spi_imx->usedma = 0;
> @@ -964,6 +1057,12 @@ static int spi_imx_setupxfer(struct spi_device *spi,
>  			return ret;
>  	}
>  
> +	if (is_imx53_ecspi(spi_imx) && spi_imx->slave_mode) {
> +		spi_imx->rx = mx53_ecspi_rx_slave;
> +		spi_imx->tx = mx53_ecspi_tx_slave;
> +		spi_imx->slave_burst = t->len;
> +	}
> +
>  	spi_imx->devtype_data->config(spi, &config);
>  
>  	return 0;
> @@ -1125,16 +1224,50 @@ static int spi_imx_pio_transfer(struct spi_device *spi,
>  	struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
>  	unsigned long transfer_timeout;
>  	unsigned long timeout;
> +	int ret = transfer->len;
> +
> +	if (is_imx53_ecspi(spi_imx) && spi_imx->slave_mode &&
> +	    transfer->len > MX53_MAX_TRANSFER_BYTES) {
> +		pr_err("Transaction too big, max size is %d bytes\n",
> +		       MX53_MAX_TRANSFER_BYTES);

Don't use pr_* functions when you have a struct device * available.

> +		return -EMSGSIZE;
> +	}
>  
>  	spi_imx->tx_buf = transfer->tx_buf;
>  	spi_imx->rx_buf = transfer->rx_buf;
>  	spi_imx->count = transfer->len;
>  	spi_imx->txfifo = 0;
>  
> +	if (spi_imx->slave_mode)
> +		spi_imx->slave_burst = spi_imx->count;

You have set this in spi_imx_setupxfer() already. Why here again?

> +
>  	reinit_completion(&spi_imx->xfer_done);
> +	spi_imx->slave_aborted = false;
>  
>  	spi_imx_push(spi_imx);
>  
> +	if (spi_imx->slave_mode) {
> +		spi_imx->devtype_data->intctrl(spi_imx, MXC_INT_TE |
> +							MXC_INT_RDR);
> +
> +		if (wait_for_completion_interruptible(&spi_imx->xfer_done) ||
> +		    spi_imx->slave_aborted) {
> +			dev_dbg(&spi->dev, "interrupted\n");
> +			ret = -EINTR;
> +		}
> +
> +		/* ecspi has a HW issue when works in Slave mode,
> +		 * after 64 words writtern to TXFIFO, even TXFIFO becomes empty,
> +		 * ECSPI_TXDATA keeps shift out the last word data,
> +		 * so we have to disable ECSPI when in slave mode after the
> +		 * transfer completes
> +		 */
> +		if (spi_imx->devtype_data->disable)
> +			spi_imx->devtype_data->disable(spi_imx);
> +
> +		goto out;
> +	}
> +
>  	spi_imx->devtype_data->intctrl(spi_imx, MXC_INT_TE);
>  
>  	transfer_timeout = spi_imx_calculate_timeout(spi_imx, transfer->len);

You are adding more lines to spi_imx_pio_transfer() than the original
function had, most of them inside a if(spi_imx->slave_mode).
It would probably more readable if you introduced a separate
spi_imx_pio_transfer_slave().

Sascha
Wang, Jiada June 2, 2017, 1:13 p.m. UTC | #2
Hi Sascha

On 05/31/2017 05:10 AM, Sascha Hauer wrote:
> On Wed, May 31, 2017 at 02:19:58AM -0700, jiada_wang@mentor.com wrote:
>> From: Jiada Wang <jiada_wang@mentor.com>
>>
>> Previously i.MX SPI controller only works in Master mode.
>> This patch adds support to i.MX51, i.MX53 and i.MX6 ECSPI
>> controller to work also in Slave mode.
>>
>> Currently SPI Slave mode support patch has the following limitations:
>> 1. The stale data in RXFIFO will be dropped when the Slave does any new
>>    transfer.
>> 2. One transfer can be finished only after all transfer->len data been
>>    transferred to master device
>> 3. Slave device only accepts transfer->len data. Any data longer than this
>>    from master device will be dropped. Any data shorter than this from
>>    master will cause SPI to stuck due to mentioned HW limitation 2.
>> 4. Only PIO transfer is supported in Slave mode.
>>
>> Following HW limitation applies:
>> 1.  ECSPI has a HW issue when works in Slave mode, after 64
>>     words written to TXFIFO, even TXFIFO becomes empty,
>>     ECSPI_TXDATA keeps shift out the last word data,
>>     so we have to disable ECSPI when in slave mode after the
>>     transfer completes
>> 2.  Due to Freescale errata ERR003775 "eCSPI: Burst completion by Chip
>>     Select (SS) signal in Slave mode is not functional" burst size must
>>     be set exactly to the size of the transfer. This limit SPI transaction
>>     with maximum 2^12 bits. This errata affects i.MX53 and i.MX6 ECSPI
>>     controllers.
>>
>> Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
>> ---
>>  drivers/spi/spi-imx.c | 227 +++++++++++++++++++++++++++++++++++++++++++-------
>>  1 file changed, 195 insertions(+), 32 deletions(-)
>>
>> diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
>> index 765856c..a227a30 100644
>> --- a/drivers/spi/spi-imx.c
>> +++ b/drivers/spi/spi-imx.c
>> @@ -53,9 +53,13 @@
>>  /* generic defines to abstract from the different register layouts */
>>  #define MXC_INT_RR	(1 << 0) /* Receive data ready interrupt */
>>  #define MXC_INT_TE	(1 << 1) /* Transmit FIFO empty interrupt */
>> +#define MXC_INT_RDR	BIT(4) /* Receive date threshold interrupt */
>>  
>>  /* The maximum  bytes that a sdma BD can transfer.*/
>>  #define MAX_SDMA_BD_BYTES  (1 << 15)
>> +/* The maximum bytes that IMX53_ECSPI can transfer in slave mode.*/
>> +#define MX53_MAX_TRANSFER_BYTES		512
>> +
>>  struct spi_imx_config {
>>  	unsigned int speed_hz;
>>  	unsigned int bpw;
>> @@ -79,6 +83,7 @@ struct spi_imx_devtype_data {
>>  	void (*trigger)(struct spi_imx_data *);
>>  	int (*rx_available)(struct spi_imx_data *);
>>  	void (*reset)(struct spi_imx_data *);
>> +	void (*disable)(struct spi_imx_data *);
>>  	enum spi_imx_devtype devtype;
>>  };
>>  
>> @@ -105,6 +110,11 @@ struct spi_imx_data {
>>  	const void *tx_buf;
>>  	unsigned int txfifo; /* number of words pushed in tx FIFO */
>>  
>> +	/* Slave mode */
>> +	bool slave_mode;
>> +	bool slave_aborted;
>> +	unsigned int slave_burst;
>> +
>>  	/* DMA */
>>  	bool usedma;
>>  	u32 wml;
>> @@ -157,6 +167,17 @@ static inline bool spi_imx_has_dmamode(struct spi_imx_data *d)
>>  	}
>>  }
>>  
>> +static inline bool spi_imx_has_slavemode(const struct spi_imx_devtype_data *d)
>> +{
>> +	switch (d->devtype) {
>> +	case IMX51_ECSPI:
>> +	case IMX53_ECSPI:
>> +		return true;
>> +	default:
>> +		return false;
>> +	}
>> +}
> Add a new boolean flag to struct spi_imx_devtype_data instead.
>
>
>> +
>>  #define MXC_SPI_BUF_RX(type)						\
>>  static void spi_imx_buf_rx_##type(struct spi_imx_data *spi_imx)		\
>>  {									\
>> @@ -287,6 +308,7 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
>>  #define MX51_ECSPI_INT		0x10
>>  #define MX51_ECSPI_INT_TEEN		(1 <<  0)
>>  #define MX51_ECSPI_INT_RREN		(1 <<  3)
>> +#define MX51_ECSPI_INT_RDREN		(1 <<  4)
>>  
>>  #define MX51_ECSPI_DMA      0x14
>>  #define MX51_ECSPI_DMA_TX_WML(wml)	((wml) & 0x3f)
>> @@ -303,6 +325,51 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
>>  #define MX51_ECSPI_TESTREG	0x20
>>  #define MX51_ECSPI_TESTREG_LBC	BIT(31)
>>  
>> +static void mx53_ecspi_rx_slave(struct spi_imx_data *spi_imx)
>> +{
>> +	u32 val = be32_to_cpu(readl(spi_imx->base + MXC_CSPIRXDATA));
>> +
>> +	if (spi_imx->rx_buf) {
>> +		int shift = spi_imx->slave_burst % sizeof(val);
>> +
>> +		if (shift) {
>> +			memcpy(spi_imx->rx_buf,
>> +			       ((u8 *)&val) + sizeof(val) - shift, shift);
>> +		} else {
>> +			*((u32 *)spi_imx->rx_buf) = val;
>> +			shift = sizeof(val);
>> +		}
>> +
>> +		spi_imx->rx_buf += shift;
>> +		spi_imx->slave_burst -= shift;
>> +	}
>> +}
>> +
>> +static void mx53_ecspi_tx_slave(struct spi_imx_data *spi_imx)
>> +{
>> +	u32 val = 0;
>> +	int shift = spi_imx->count % sizeof(val);
>> +
>> +	if (spi_imx->tx_buf) {
>> +		if (shift) {
>> +			memcpy(((u8 *)&val) + sizeof(val) - shift,
>> +			       spi_imx->tx_buf, shift);
>> +		} else {
>> +			val = *((u32 *)spi_imx->tx_buf);
>> +			shift = sizeof(val);
>> +		}
>> +		val = cpu_to_be32(val);
>> +		spi_imx->tx_buf += shift;
>> +	}
>> +
>> +	if (!shift)
>> +		shift = sizeof(val);
> A better name for 'shift' is n_bytes. Its value should be calculated
> before the if (spi_imx->tx_buf) block. Then you can use memcpy for the
> four byte case aswell.
>
>
> But anyway, have you tested this function for anything with
> spi_imx->count % sizeof(val) != 0? In this case you have to put the fill
> the FIFO only partly somewhere. I would assume you have to do this at
> the end of the transfer, but you do this at the beginning. Can this
> work?
Yes, I have tested the case when "spi_imx->count % sizeof(val) != 0", it
works.
based on what I observed,
when the data bits written to FIFO exceeds burst len, then the 'old'
bits will be dropped.

I will update this patch set to address your review comments in v3

Thanks,
Jiada

>> +
>> +	spi_imx->count -= shift;
>> +
>> +	writel(val, spi_imx->base + MXC_CSPITXDATA);
>> +}
>> +
>>  /* MX51 eCSPI */
>>  static unsigned int mx51_ecspi_clkdiv(struct spi_imx_data *spi_imx,
>>  				      unsigned int fspi, unsigned int *fres)
>> @@ -352,6 +419,9 @@ static void mx51_ecspi_intctrl(struct spi_imx_data *spi_imx, int enable)
>>  	if (enable & MXC_INT_RR)
>>  		val |= MX51_ECSPI_INT_RREN;
>>  
>> +	if (enable & MXC_INT_RDR)
>> +		val |= MX51_ECSPI_INT_RDREN;
>> +
>>  	writel(val, spi_imx->base + MX51_ECSPI_INT);
>>  }
>>  
>> @@ -364,6 +434,15 @@ static void mx51_ecspi_trigger(struct spi_imx_data *spi_imx)
>>  	writel(reg, spi_imx->base + MX51_ECSPI_CTRL);
>>  }
>>  
>> +static void __maybe_unused mx51_ecspi_disable(struct spi_imx_data *spi_imx)
> I don't see how this function may end up unused.
>
>> +{
>> +	u32 ctrl;
>> +
>> +	ctrl = readl(spi_imx->base + MX51_ECSPI_CTRL);
>> +	ctrl &= ~MX51_ECSPI_CTRL_ENABLE;
>> +	writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
>> +}
>> +
>>  static int mx51_ecspi_config(struct spi_device *spi,
>>  			     struct spi_imx_config *config)
>>  {
>> @@ -372,14 +451,11 @@ static int mx51_ecspi_config(struct spi_device *spi,
>>  	u32 clk = config->speed_hz, delay, reg;
>>  	u32 cfg = readl(spi_imx->base + MX51_ECSPI_CONFIG);
>>  
>> -	/*
>> -	 * The hardware seems to have a race condition when changing modes. The
>> -	 * current assumption is that the selection of the channel arrives
>> -	 * earlier in the hardware than the mode bits when they are written at
>> -	 * the same time.
>> -	 * So set master mode for all channels as we do not support slave mode.
>> -	 */
>> -	ctrl |= MX51_ECSPI_CTRL_MODE_MASK;
>> +	/* set Master or Slave mode */
>> +	if (spi_imx->slave_mode)
>> +		ctrl &= ~MX51_ECSPI_CTRL_MODE_MASK;
>> +	else
>> +		ctrl |= MX51_ECSPI_CTRL_MODE_MASK;
>>  
>>  	/*
>>  	 * Enable SPI_RDY handling (falling edge/level triggered).
>> @@ -394,9 +470,21 @@ static int mx51_ecspi_config(struct spi_device *spi,
>>  	/* set chip select to use */
>>  	ctrl |= MX51_ECSPI_CTRL_CS(spi->chip_select);
>>  
>> -	ctrl |= (config->bpw - 1) << MX51_ECSPI_CTRL_BL_OFFSET;
>> +	if (spi_imx->slave_mode && is_imx53_ecspi(spi_imx))
>> +		ctrl |= (spi_imx->slave_burst * 8 - 1)
>> +			<< MX51_ECSPI_CTRL_BL_OFFSET;
>> +	else
>> +		ctrl |= (config->bpw - 1) << MX51_ECSPI_CTRL_BL_OFFSET;
>>  
>> -	cfg |= MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);
>> +	/*
>> +	 * eCSPI burst completion by Chip Select signal in Slave mode
>> +	 * is not functional for imx53 Soc, config SPI burst completed when
>> +	 * BURST_LENGTH + 1 bits are received
>> +	 */
>> +	if (spi_imx->slave_mode && is_imx53_ecspi(spi_imx))
>> +		cfg &= ~MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);
>> +	else
>> +		cfg |= MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);
>>  
>>  	if (spi->mode & SPI_CPHA)
>>  		cfg |= MX51_ECSPI_CONFIG_SCLKPHA(spi->chip_select);
>> @@ -775,6 +863,7 @@ static struct spi_imx_devtype_data imx51_ecspi_devtype_data = {
>>  	.trigger = mx51_ecspi_trigger,
>>  	.rx_available = mx51_ecspi_rx_available,
>>  	.reset = mx51_ecspi_reset,
>> +	.disable = mx51_ecspi_disable,
>>  	.devtype = IMX51_ECSPI,
>>  };
>>  
>> @@ -784,6 +873,7 @@ static struct spi_imx_devtype_data imx53_ecspi_devtype_data = {
>>  	.trigger = mx51_ecspi_trigger,
>>  	.rx_available = mx51_ecspi_rx_available,
>>  	.reset = mx51_ecspi_reset,
>> +	.disable = mx51_ecspi_disable,
>>  	.devtype = IMX53_ECSPI,
>>  };
>>  
>> @@ -846,14 +936,16 @@ static void spi_imx_push(struct spi_imx_data *spi_imx)
>>  		spi_imx->txfifo++;
>>  	}
>>  
>> -	spi_imx->devtype_data->trigger(spi_imx);
>> +	if (!spi_imx->slave_mode)
>> +		spi_imx->devtype_data->trigger(spi_imx);
>>  }
>>  
>>  static irqreturn_t spi_imx_isr(int irq, void *dev_id)
>>  {
>>  	struct spi_imx_data *spi_imx = dev_id;
>>  
>> -	while (spi_imx->devtype_data->rx_available(spi_imx)) {
>> +	while (spi_imx->txfifo &&
>> +	       spi_imx->devtype_data->rx_available(spi_imx)) {
>>  		spi_imx->rx(spi_imx);
>>  		spi_imx->txfifo--;
>>  	}
>> @@ -952,7 +1044,8 @@ static int spi_imx_setupxfer(struct spi_device *spi,
>>  		spi_imx->tx = spi_imx_buf_tx_u32;
>>  	}
>>  
>> -	if (spi_imx_can_dma(spi_imx->bitbang.master, spi, t))
>> +	if (!spi_imx->slave_mode &&
>> +	    spi_imx_can_dma(spi_imx->bitbang.master, spi, t))
>>  		spi_imx->usedma = 1;
> So in spi_imx_can_dma() you may return true for a slave mode transfer
> and here we end up doing PIO for the same transfer. That doesn't look
> correct. You should move the test for slave mode into spi_imx_can_dma().
>
>>  	else
>>  		spi_imx->usedma = 0;
>> @@ -964,6 +1057,12 @@ static int spi_imx_setupxfer(struct spi_device *spi,
>>  			return ret;
>>  	}
>>  
>> +	if (is_imx53_ecspi(spi_imx) && spi_imx->slave_mode) {
>> +		spi_imx->rx = mx53_ecspi_rx_slave;
>> +		spi_imx->tx = mx53_ecspi_tx_slave;
>> +		spi_imx->slave_burst = t->len;
>> +	}
>> +
>>  	spi_imx->devtype_data->config(spi, &config);
>>  
>>  	return 0;
>> @@ -1125,16 +1224,50 @@ static int spi_imx_pio_transfer(struct spi_device *spi,
>>  	struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
>>  	unsigned long transfer_timeout;
>>  	unsigned long timeout;
>> +	int ret = transfer->len;
>> +
>> +	if (is_imx53_ecspi(spi_imx) && spi_imx->slave_mode &&
>> +	    transfer->len > MX53_MAX_TRANSFER_BYTES) {
>> +		pr_err("Transaction too big, max size is %d bytes\n",
>> +		       MX53_MAX_TRANSFER_BYTES);
> Don't use pr_* functions when you have a struct device * available.
>
>> +		return -EMSGSIZE;
>> +	}
>>  
>>  	spi_imx->tx_buf = transfer->tx_buf;
>>  	spi_imx->rx_buf = transfer->rx_buf;
>>  	spi_imx->count = transfer->len;
>>  	spi_imx->txfifo = 0;
>>  
>> +	if (spi_imx->slave_mode)
>> +		spi_imx->slave_burst = spi_imx->count;
> You have set this in spi_imx_setupxfer() already. Why here again?
>
>> +
>>  	reinit_completion(&spi_imx->xfer_done);
>> +	spi_imx->slave_aborted = false;
>>  
>>  	spi_imx_push(spi_imx);
>>  
>> +	if (spi_imx->slave_mode) {
>> +		spi_imx->devtype_data->intctrl(spi_imx, MXC_INT_TE |
>> +							MXC_INT_RDR);
>> +
>> +		if (wait_for_completion_interruptible(&spi_imx->xfer_done) ||
>> +		    spi_imx->slave_aborted) {
>> +			dev_dbg(&spi->dev, "interrupted\n");
>> +			ret = -EINTR;
>> +		}
>> +
>> +		/* ecspi has a HW issue when works in Slave mode,
>> +		 * after 64 words writtern to TXFIFO, even TXFIFO becomes empty,
>> +		 * ECSPI_TXDATA keeps shift out the last word data,
>> +		 * so we have to disable ECSPI when in slave mode after the
>> +		 * transfer completes
>> +		 */
>> +		if (spi_imx->devtype_data->disable)
>> +			spi_imx->devtype_data->disable(spi_imx);
>> +
>> +		goto out;
>> +	}
>> +
>>  	spi_imx->devtype_data->intctrl(spi_imx, MXC_INT_TE);
>>  
>>  	transfer_timeout = spi_imx_calculate_timeout(spi_imx, transfer->len);
> You are adding more lines to spi_imx_pio_transfer() than the original
> function had, most of them inside a if(spi_imx->slave_mode).
> It would probably more readable if you introduced a separate
> spi_imx_pio_transfer_slave().
>
> Sascha
>
>

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s.hauer@pengutronix.de June 7, 2017, 8:33 a.m. UTC | #3
On Fri, Jun 02, 2017 at 06:13:07AM -0700, Jiada Wang wrote:
> Hi Sascha
> 
> On 05/31/2017 05:10 AM, Sascha Hauer wrote:
> >> +
> >> +static void mx53_ecspi_tx_slave(struct spi_imx_data *spi_imx)
> >> +{
> >> +	u32 val = 0;
> >> +	int shift = spi_imx->count % sizeof(val);
> >> +
> >> +	if (spi_imx->tx_buf) {
> >> +		if (shift) {
> >> +			memcpy(((u8 *)&val) + sizeof(val) - shift,
> >> +			       spi_imx->tx_buf, shift);
> >> +		} else {
> >> +			val = *((u32 *)spi_imx->tx_buf);
> >> +			shift = sizeof(val);
> >> +		}
> >> +		val = cpu_to_be32(val);
> >> +		spi_imx->tx_buf += shift;
> >> +	}
> >> +
> >> +	if (!shift)
> >> +		shift = sizeof(val);
> > A better name for 'shift' is n_bytes. Its value should be calculated
> > before the if (spi_imx->tx_buf) block. Then you can use memcpy for the
> > four byte case aswell.
> >
> >
> > But anyway, have you tested this function for anything with
> > spi_imx->count % sizeof(val) != 0? In this case you have to put the fill
> > the FIFO only partly somewhere. I would assume you have to do this at
> > the end of the transfer, but you do this at the beginning. Can this
> > work?
> Yes, I have tested the case when "spi_imx->count % sizeof(val) != 0", it
> works.

For the record: Yes, this seems to be right. I misread the datasheet.
When the controller is programmed to transfer 5 bytes, then it seemed
fairly logical to me that it first expects four bytes in its 32bit FIFO
and then the remaining single byte. In fact it's the other way round,
how the example of the BURST_LENGTH register description says:

0x021 A SPI burst contains the 2 LSB in first word and all 32 bits in
second word.

So the part that doesn't fill a whole FIFO width goes out first, not
last.

Sascha
diff mbox

Patch

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 765856c..a227a30 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -53,9 +53,13 @@ 
 /* generic defines to abstract from the different register layouts */
 #define MXC_INT_RR	(1 << 0) /* Receive data ready interrupt */
 #define MXC_INT_TE	(1 << 1) /* Transmit FIFO empty interrupt */
+#define MXC_INT_RDR	BIT(4) /* Receive date threshold interrupt */
 
 /* The maximum  bytes that a sdma BD can transfer.*/
 #define MAX_SDMA_BD_BYTES  (1 << 15)
+/* The maximum bytes that IMX53_ECSPI can transfer in slave mode.*/
+#define MX53_MAX_TRANSFER_BYTES		512
+
 struct spi_imx_config {
 	unsigned int speed_hz;
 	unsigned int bpw;
@@ -79,6 +83,7 @@  struct spi_imx_devtype_data {
 	void (*trigger)(struct spi_imx_data *);
 	int (*rx_available)(struct spi_imx_data *);
 	void (*reset)(struct spi_imx_data *);
+	void (*disable)(struct spi_imx_data *);
 	enum spi_imx_devtype devtype;
 };
 
@@ -105,6 +110,11 @@  struct spi_imx_data {
 	const void *tx_buf;
 	unsigned int txfifo; /* number of words pushed in tx FIFO */
 
+	/* Slave mode */
+	bool slave_mode;
+	bool slave_aborted;
+	unsigned int slave_burst;
+
 	/* DMA */
 	bool usedma;
 	u32 wml;
@@ -157,6 +167,17 @@  static inline bool spi_imx_has_dmamode(struct spi_imx_data *d)
 	}
 }
 
+static inline bool spi_imx_has_slavemode(const struct spi_imx_devtype_data *d)
+{
+	switch (d->devtype) {
+	case IMX51_ECSPI:
+	case IMX53_ECSPI:
+		return true;
+	default:
+		return false;
+	}
+}
+
 #define MXC_SPI_BUF_RX(type)						\
 static void spi_imx_buf_rx_##type(struct spi_imx_data *spi_imx)		\
 {									\
@@ -287,6 +308,7 @@  static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
 #define MX51_ECSPI_INT		0x10
 #define MX51_ECSPI_INT_TEEN		(1 <<  0)
 #define MX51_ECSPI_INT_RREN		(1 <<  3)
+#define MX51_ECSPI_INT_RDREN		(1 <<  4)
 
 #define MX51_ECSPI_DMA      0x14
 #define MX51_ECSPI_DMA_TX_WML(wml)	((wml) & 0x3f)
@@ -303,6 +325,51 @@  static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
 #define MX51_ECSPI_TESTREG	0x20
 #define MX51_ECSPI_TESTREG_LBC	BIT(31)
 
+static void mx53_ecspi_rx_slave(struct spi_imx_data *spi_imx)
+{
+	u32 val = be32_to_cpu(readl(spi_imx->base + MXC_CSPIRXDATA));
+
+	if (spi_imx->rx_buf) {
+		int shift = spi_imx->slave_burst % sizeof(val);
+
+		if (shift) {
+			memcpy(spi_imx->rx_buf,
+			       ((u8 *)&val) + sizeof(val) - shift, shift);
+		} else {
+			*((u32 *)spi_imx->rx_buf) = val;
+			shift = sizeof(val);
+		}
+
+		spi_imx->rx_buf += shift;
+		spi_imx->slave_burst -= shift;
+	}
+}
+
+static void mx53_ecspi_tx_slave(struct spi_imx_data *spi_imx)
+{
+	u32 val = 0;
+	int shift = spi_imx->count % sizeof(val);
+
+	if (spi_imx->tx_buf) {
+		if (shift) {
+			memcpy(((u8 *)&val) + sizeof(val) - shift,
+			       spi_imx->tx_buf, shift);
+		} else {
+			val = *((u32 *)spi_imx->tx_buf);
+			shift = sizeof(val);
+		}
+		val = cpu_to_be32(val);
+		spi_imx->tx_buf += shift;
+	}
+
+	if (!shift)
+		shift = sizeof(val);
+
+	spi_imx->count -= shift;
+
+	writel(val, spi_imx->base + MXC_CSPITXDATA);
+}
+
 /* MX51 eCSPI */
 static unsigned int mx51_ecspi_clkdiv(struct spi_imx_data *spi_imx,
 				      unsigned int fspi, unsigned int *fres)
@@ -352,6 +419,9 @@  static void mx51_ecspi_intctrl(struct spi_imx_data *spi_imx, int enable)
 	if (enable & MXC_INT_RR)
 		val |= MX51_ECSPI_INT_RREN;
 
+	if (enable & MXC_INT_RDR)
+		val |= MX51_ECSPI_INT_RDREN;
+
 	writel(val, spi_imx->base + MX51_ECSPI_INT);
 }
 
@@ -364,6 +434,15 @@  static void mx51_ecspi_trigger(struct spi_imx_data *spi_imx)
 	writel(reg, spi_imx->base + MX51_ECSPI_CTRL);
 }
 
+static void __maybe_unused mx51_ecspi_disable(struct spi_imx_data *spi_imx)
+{
+	u32 ctrl;
+
+	ctrl = readl(spi_imx->base + MX51_ECSPI_CTRL);
+	ctrl &= ~MX51_ECSPI_CTRL_ENABLE;
+	writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
+}
+
 static int mx51_ecspi_config(struct spi_device *spi,
 			     struct spi_imx_config *config)
 {
@@ -372,14 +451,11 @@  static int mx51_ecspi_config(struct spi_device *spi,
 	u32 clk = config->speed_hz, delay, reg;
 	u32 cfg = readl(spi_imx->base + MX51_ECSPI_CONFIG);
 
-	/*
-	 * The hardware seems to have a race condition when changing modes. The
-	 * current assumption is that the selection of the channel arrives
-	 * earlier in the hardware than the mode bits when they are written at
-	 * the same time.
-	 * So set master mode for all channels as we do not support slave mode.
-	 */
-	ctrl |= MX51_ECSPI_CTRL_MODE_MASK;
+	/* set Master or Slave mode */
+	if (spi_imx->slave_mode)
+		ctrl &= ~MX51_ECSPI_CTRL_MODE_MASK;
+	else
+		ctrl |= MX51_ECSPI_CTRL_MODE_MASK;
 
 	/*
 	 * Enable SPI_RDY handling (falling edge/level triggered).
@@ -394,9 +470,21 @@  static int mx51_ecspi_config(struct spi_device *spi,
 	/* set chip select to use */
 	ctrl |= MX51_ECSPI_CTRL_CS(spi->chip_select);
 
-	ctrl |= (config->bpw - 1) << MX51_ECSPI_CTRL_BL_OFFSET;
+	if (spi_imx->slave_mode && is_imx53_ecspi(spi_imx))
+		ctrl |= (spi_imx->slave_burst * 8 - 1)
+			<< MX51_ECSPI_CTRL_BL_OFFSET;
+	else
+		ctrl |= (config->bpw - 1) << MX51_ECSPI_CTRL_BL_OFFSET;
 
-	cfg |= MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);
+	/*
+	 * eCSPI burst completion by Chip Select signal in Slave mode
+	 * is not functional for imx53 Soc, config SPI burst completed when
+	 * BURST_LENGTH + 1 bits are received
+	 */
+	if (spi_imx->slave_mode && is_imx53_ecspi(spi_imx))
+		cfg &= ~MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);
+	else
+		cfg |= MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);
 
 	if (spi->mode & SPI_CPHA)
 		cfg |= MX51_ECSPI_CONFIG_SCLKPHA(spi->chip_select);
@@ -775,6 +863,7 @@  static struct spi_imx_devtype_data imx51_ecspi_devtype_data = {
 	.trigger = mx51_ecspi_trigger,
 	.rx_available = mx51_ecspi_rx_available,
 	.reset = mx51_ecspi_reset,
+	.disable = mx51_ecspi_disable,
 	.devtype = IMX51_ECSPI,
 };
 
@@ -784,6 +873,7 @@  static struct spi_imx_devtype_data imx53_ecspi_devtype_data = {
 	.trigger = mx51_ecspi_trigger,
 	.rx_available = mx51_ecspi_rx_available,
 	.reset = mx51_ecspi_reset,
+	.disable = mx51_ecspi_disable,
 	.devtype = IMX53_ECSPI,
 };
 
@@ -846,14 +936,16 @@  static void spi_imx_push(struct spi_imx_data *spi_imx)
 		spi_imx->txfifo++;
 	}
 
-	spi_imx->devtype_data->trigger(spi_imx);
+	if (!spi_imx->slave_mode)
+		spi_imx->devtype_data->trigger(spi_imx);
 }
 
 static irqreturn_t spi_imx_isr(int irq, void *dev_id)
 {
 	struct spi_imx_data *spi_imx = dev_id;
 
-	while (spi_imx->devtype_data->rx_available(spi_imx)) {
+	while (spi_imx->txfifo &&
+	       spi_imx->devtype_data->rx_available(spi_imx)) {
 		spi_imx->rx(spi_imx);
 		spi_imx->txfifo--;
 	}
@@ -952,7 +1044,8 @@  static int spi_imx_setupxfer(struct spi_device *spi,
 		spi_imx->tx = spi_imx_buf_tx_u32;
 	}
 
-	if (spi_imx_can_dma(spi_imx->bitbang.master, spi, t))
+	if (!spi_imx->slave_mode &&
+	    spi_imx_can_dma(spi_imx->bitbang.master, spi, t))
 		spi_imx->usedma = 1;
 	else
 		spi_imx->usedma = 0;
@@ -964,6 +1057,12 @@  static int spi_imx_setupxfer(struct spi_device *spi,
 			return ret;
 	}
 
+	if (is_imx53_ecspi(spi_imx) && spi_imx->slave_mode) {
+		spi_imx->rx = mx53_ecspi_rx_slave;
+		spi_imx->tx = mx53_ecspi_tx_slave;
+		spi_imx->slave_burst = t->len;
+	}
+
 	spi_imx->devtype_data->config(spi, &config);
 
 	return 0;
@@ -1125,16 +1224,50 @@  static int spi_imx_pio_transfer(struct spi_device *spi,
 	struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
 	unsigned long transfer_timeout;
 	unsigned long timeout;
+	int ret = transfer->len;
+
+	if (is_imx53_ecspi(spi_imx) && spi_imx->slave_mode &&
+	    transfer->len > MX53_MAX_TRANSFER_BYTES) {
+		pr_err("Transaction too big, max size is %d bytes\n",
+		       MX53_MAX_TRANSFER_BYTES);
+		return -EMSGSIZE;
+	}
 
 	spi_imx->tx_buf = transfer->tx_buf;
 	spi_imx->rx_buf = transfer->rx_buf;
 	spi_imx->count = transfer->len;
 	spi_imx->txfifo = 0;
 
+	if (spi_imx->slave_mode)
+		spi_imx->slave_burst = spi_imx->count;
+
 	reinit_completion(&spi_imx->xfer_done);
+	spi_imx->slave_aborted = false;
 
 	spi_imx_push(spi_imx);
 
+	if (spi_imx->slave_mode) {
+		spi_imx->devtype_data->intctrl(spi_imx, MXC_INT_TE |
+							MXC_INT_RDR);
+
+		if (wait_for_completion_interruptible(&spi_imx->xfer_done) ||
+		    spi_imx->slave_aborted) {
+			dev_dbg(&spi->dev, "interrupted\n");
+			ret = -EINTR;
+		}
+
+		/* ecspi has a HW issue when works in Slave mode,
+		 * after 64 words writtern to TXFIFO, even TXFIFO becomes empty,
+		 * ECSPI_TXDATA keeps shift out the last word data,
+		 * so we have to disable ECSPI when in slave mode after the
+		 * transfer completes
+		 */
+		if (spi_imx->devtype_data->disable)
+			spi_imx->devtype_data->disable(spi_imx);
+
+		goto out;
+	}
+
 	spi_imx->devtype_data->intctrl(spi_imx, MXC_INT_TE);
 
 	transfer_timeout = spi_imx_calculate_timeout(spi_imx, transfer->len);
@@ -1147,7 +1280,8 @@  static int spi_imx_pio_transfer(struct spi_device *spi,
 		return -ETIMEDOUT;
 	}
 
-	return transfer->len;
+out:
+	return ret;
 }
 
 static int spi_imx_transfer(struct spi_device *spi,
@@ -1155,6 +1289,10 @@  static int spi_imx_transfer(struct spi_device *spi,
 {
 	struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
 
+	/* flush rxfifo before transfer */
+	while (spi_imx->devtype_data->rx_available(spi_imx))
+		spi_imx->rx(spi_imx);
+
 	if (spi_imx->usedma)
 		return spi_imx_dma_transfer(spi_imx, transfer);
 	else
@@ -1208,6 +1346,16 @@  spi_imx_unprepare_message(struct spi_master *master, struct spi_message *msg)
 	return 0;
 }
 
+static int spi_imx_slave_abort(struct spi_master *master)
+{
+	struct spi_imx_data *spi_imx = spi_master_get_devdata(master);
+
+	spi_imx->slave_aborted = true;
+	complete(&spi_imx->xfer_done);
+
+	return 0;
+}
+
 static int spi_imx_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
@@ -1219,13 +1367,24 @@  static int spi_imx_probe(struct platform_device *pdev)
 	struct spi_imx_data *spi_imx;
 	struct resource *res;
 	int i, ret, irq, spi_drctl;
+	const struct spi_imx_devtype_data *devtype_data = of_id ? of_id->data :
+		(struct spi_imx_devtype_data *)pdev->id_entry->driver_data;
+	bool slave_mode;
 
 	if (!np && !mxc_platform_info) {
 		dev_err(&pdev->dev, "can't get the platform data\n");
 		return -EINVAL;
 	}
 
-	master = spi_alloc_master(&pdev->dev, sizeof(struct spi_imx_data));
+	slave_mode = spi_imx_has_slavemode(devtype_data) &&
+			of_property_read_bool(np, "spi-slave");
+	if (slave_mode)
+		master = spi_alloc_slave(&pdev->dev,
+					 sizeof(struct spi_imx_data));
+	else
+		master = spi_alloc_master(&pdev->dev,
+					  sizeof(struct spi_imx_data));
+
 	ret = of_property_read_u32(np, "fsl,spi-rdy-drctl", &spi_drctl);
 	if ((ret < 0) || (spi_drctl >= 0x3)) {
 		/* '11' is reserved */
@@ -1243,9 +1402,9 @@  static int spi_imx_probe(struct platform_device *pdev)
 	spi_imx = spi_master_get_devdata(master);
 	spi_imx->bitbang.master = master;
 	spi_imx->dev = &pdev->dev;
+	spi_imx->slave_mode = slave_mode;
 
-	spi_imx->devtype_data = of_id ? of_id->data :
-		(struct spi_imx_devtype_data *)pdev->id_entry->driver_data;
+	spi_imx->devtype_data = devtype_data;
 
 	if (mxc_platform_info) {
 		master->num_chipselect = mxc_platform_info->num_chipselect;
@@ -1265,6 +1424,7 @@  static int spi_imx_probe(struct platform_device *pdev)
 	spi_imx->bitbang.master->cleanup = spi_imx_cleanup;
 	spi_imx->bitbang.master->prepare_message = spi_imx_prepare_message;
 	spi_imx->bitbang.master->unprepare_message = spi_imx_unprepare_message;
+	spi_imx->bitbang.master->slave_abort = spi_imx_slave_abort;
 	spi_imx->bitbang.master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
 	if (is_imx35_cspi(spi_imx) || is_imx51_ecspi(spi_imx) ||
 	    is_imx53_ecspi(spi_imx))
@@ -1341,23 +1501,26 @@  static int spi_imx_probe(struct platform_device *pdev)
 		goto out_clk_put;
 	}
 
-	if (!master->cs_gpios) {
-		dev_err(&pdev->dev, "No CS GPIOs available\n");
-		ret = -EINVAL;
-		goto out_clk_put;
-	}
-
-	for (i = 0; i < master->num_chipselect; i++) {
-		if (!gpio_is_valid(master->cs_gpios[i]))
-			continue;
-
-		ret = devm_gpio_request(&pdev->dev, master->cs_gpios[i],
-					DRIVER_NAME);
-		if (ret) {
-			dev_err(&pdev->dev, "Can't get CS GPIO %i\n",
-				master->cs_gpios[i]);
+	if (!spi_imx->slave_mode) {
+		if (!master->cs_gpios) {
+			dev_err(&pdev->dev, "No CS GPIOs available\n");
+			ret = -EINVAL;
 			goto out_clk_put;
 		}
+
+		for (i = 0; i < master->num_chipselect; i++) {
+			if (!gpio_is_valid(master->cs_gpios[i]))
+				continue;
+
+			ret = devm_gpio_request(&pdev->dev,
+						master->cs_gpios[i],
+						DRIVER_NAME);
+			if (ret) {
+				dev_err(&pdev->dev, "Can't get CS GPIO %i\n",
+					master->cs_gpios[i]);
+				goto out_clk_put;
+			}
+		}
 	}
 
 	dev_info(&pdev->dev, "probed\n");