Commit 2e829ccc authored by Hans Hu's avatar Hans Hu Committed by Andi Shyti
Browse files

i2c: wmt: fix a bug when thread blocked 



During each byte access, the host performs clock stretching.

To reduce the host performs clock stretching, move most of
the per-msg processing to the interrupt context.

Suggested-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: default avatarHans Hu <hanshu-oc@zhaoxin.com>
Signed-off-by: default avatarAndi Shyti <andi.shyti@kernel.org>
parent 013fa161

drivers/i2c/busses/i2c-viai2c-common.c

+76 −69
Original line number Diff line number Diff line
@@ -18,37 +18,18 @@ int viai2c_wait_bus_not_busy(struct viai2c *i2c) 
	return 0;

}



int viai2c_check_status(struct viai2c *i2c)

{

	int ret = 0;

	unsigned long time_left;



	time_left = wait_for_completion_timeout(&i2c->complete,

						msecs_to_jiffies(500));

	if (!time_left)

		return -ETIMEDOUT;



	if (i2c->cmd_status & VIAI2C_ISR_NACK_ADDR)

		ret = -EIO;



	if (i2c->cmd_status & VIAI2C_ISR_SCL_TIMEOUT)

		ret = -ETIMEDOUT;



	return ret;

}



static int viai2c_write(struct viai2c *i2c, struct i2c_msg *pmsg, int last)

{

	u16 val, tcr_val = i2c->tcr;

	int ret;

	int xfer_len = 0;



	i2c->last = last;



	if (pmsg->len == 0) {

		/*

		 * We still need to run through the while (..) once, so

		 * start at -1 and break out early from the loop

		 */

		xfer_len = -1;

		i2c->xfered_len = -1;

		writew(0, i2c->base + VIAI2C_REG_CDR);

	} else {

		writew(pmsg->buf[0] & 0xFF, i2c->base + VIAI2C_REG_CDR);
@@ -73,42 +54,15 @@ static int viai2c_write(struct viai2c *i2c, struct i2c_msg *pmsg, int last) 
		writew(val, i2c->base + VIAI2C_REG_CR);

	}



	while (xfer_len < pmsg->len) {

		ret = viai2c_check_status(i2c);

		if (ret)

			return ret;



		xfer_len++;



		val = readw(i2c->base + VIAI2C_REG_CSR);

		if (val & VIAI2C_CSR_RCV_NOT_ACK) {

			dev_dbg(i2c->dev, "write RCV NACK error\n");

			return -EIO;

		}



		if (pmsg->len == 0) {

			val = VIAI2C_CR_TX_END | VIAI2C_CR_CPU_RDY | VIAI2C_CR_ENABLE;

			writew(val, i2c->base + VIAI2C_REG_CR);

			break;

		}



		if (xfer_len == pmsg->len) {

			if (last != 1)

				writew(VIAI2C_CR_ENABLE, i2c->base + VIAI2C_REG_CR);

		} else {

			writew(pmsg->buf[xfer_len] & 0xFF, i2c->base + VIAI2C_REG_CDR);

			writew(VIAI2C_CR_CPU_RDY | VIAI2C_CR_ENABLE, i2c->base + VIAI2C_REG_CR);

		}

	}

	if (!wait_for_completion_timeout(&i2c->complete, VIAI2C_TIMEOUT))

		return -ETIMEDOUT;



	return 0;

	return i2c->ret;

}



static int viai2c_read(struct viai2c *i2c, struct i2c_msg *pmsg)

{

	u16 val, tcr_val = i2c->tcr;

	int ret;

	u32 xfer_len = 0;



	val = readw(i2c->base + VIAI2C_REG_CR);

	val &= ~(VIAI2C_CR_TX_END | VIAI2C_CR_RX_END);
@@ -133,21 +87,10 @@ static int viai2c_read(struct viai2c *i2c, struct i2c_msg *pmsg) 
		writew(val, i2c->base + VIAI2C_REG_CR);

	}



	while (xfer_len < pmsg->len) {

		ret = viai2c_check_status(i2c);

		if (ret)

			return ret;



		pmsg->buf[xfer_len] = readw(i2c->base + VIAI2C_REG_CDR) >> 8;

		xfer_len++;



		val = readw(i2c->base + VIAI2C_REG_CR) | VIAI2C_CR_CPU_RDY;

		if (xfer_len == pmsg->len - 1)

			val |= VIAI2C_CR_RX_END;

		writew(val, i2c->base + VIAI2C_REG_CR);

	}

	if (!wait_for_completion_timeout(&i2c->complete, VIAI2C_TIMEOUT))

		return -ETIMEDOUT;



	return 0;

	return i2c->ret;

}



int viai2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
@@ -165,6 +108,9 @@ int viai2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) 
				return ret;

		}



		i2c->msg = pmsg;

		i2c->xfered_len = 0;



		if (pmsg->flags & I2C_M_RD)

			ret = viai2c_read(i2c, pmsg);

		else
@@ -174,14 +120,75 @@ int viai2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) 
	return (ret < 0) ? ret : i;

}



/*

 * Main process of the byte mode xfer

 *

 * Return value indicates whether the transfer is complete

 *  1: all the data has been successfully transferred

 *  0: there is still data that needs to be transferred

 *  -EIO: error occurred

 */

static int viai2c_irq_xfer(struct viai2c *i2c)

{

	u16 val;

	struct i2c_msg *msg = i2c->msg;

	u8 read = msg->flags & I2C_M_RD;

	void __iomem *base = i2c->base;



	if (read) {

		msg->buf[i2c->xfered_len] = readw(base + VIAI2C_REG_CDR) >> 8;



		val = readw(base + VIAI2C_REG_CR) | VIAI2C_CR_CPU_RDY;

		if (i2c->xfered_len == msg->len - 2)

			val |= VIAI2C_CR_RX_END;

		writew(val, base + VIAI2C_REG_CR);

	} else {

		val = readw(base + VIAI2C_REG_CSR);

		if (val & VIAI2C_CSR_RCV_NOT_ACK)

			return -EIO;



		/* I2C_SMBUS_QUICK */

		if (msg->len == 0) {

			val = VIAI2C_CR_TX_END | VIAI2C_CR_CPU_RDY | VIAI2C_CR_ENABLE;

			writew(val, base + VIAI2C_REG_CR);

			return 1;

		}



		if ((i2c->xfered_len + 1) == msg->len) {

			if (!i2c->last)

				writew(VIAI2C_CR_ENABLE, base + VIAI2C_REG_CR);

		} else {

			writew(msg->buf[i2c->xfered_len + 1] & 0xFF, base + VIAI2C_REG_CDR);

			writew(VIAI2C_CR_CPU_RDY | VIAI2C_CR_ENABLE, base + VIAI2C_REG_CR);

		}

	}



	i2c->xfered_len++;



	return i2c->xfered_len == msg->len;

}



static irqreturn_t viai2c_isr(int irq, void *data)

{

	struct viai2c *i2c = data;

	u8 status;



	/* save the status and write-clear it */

	i2c->cmd_status = readw(i2c->base + VIAI2C_REG_ISR);

	writew(i2c->cmd_status, i2c->base + VIAI2C_REG_ISR);

	status = readw(i2c->base + VIAI2C_REG_ISR);

	writew(status, i2c->base + VIAI2C_REG_ISR);



	i2c->ret = 0;

	if (status & VIAI2C_ISR_NACK_ADDR)

		i2c->ret = -EIO;



	if (status & VIAI2C_ISR_SCL_TIMEOUT)

		i2c->ret = -ETIMEDOUT;



	if (!i2c->ret)

		i2c->ret = viai2c_irq_xfer(i2c);



	/* All the data has been successfully transferred or error occurred */

	if (i2c->ret)

		complete(&i2c->complete);



	return IRQ_HANDLED;

drivers/i2c/busses/i2c-viai2c-common.h

+4 −2
Original line number Diff line number Diff line
@@ -58,11 +58,13 @@ struct viai2c { 
	struct clk		*clk;

	u16			tcr;

	int			irq;

	u16			cmd_status;

	u16			xfered_len;

	struct i2c_msg		*msg;

	int			ret;

	bool			last;

};



int viai2c_wait_bus_not_busy(struct viai2c *i2c);

int viai2c_check_status(struct viai2c *i2c);

int viai2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num);

int viai2c_init(struct platform_device *pdev, struct viai2c **pi2c);