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Commit 5a0d5f5f authored by Troy Kisky's avatar Troy Kisky Committed by Jean Delvare
Browse files

i2c-davinci: Fix signal handling bug 



If wait_for_completion_interruptible_timeout exits due
to a signal, the i2c bus was locking up.

Signed-off-by: default avatarTroy Kisky <troy.kisky@boundarydevices.com>
Signed-off-by: default avatarKevin Hilman <khilman@mvista.com>
Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent 0ab56e20

drivers/i2c/busses/i2c-davinci.c

+52 −10
Original line number Diff line number Diff line
@@ -85,6 +85,7 @@ 
#define DAVINCI_I2C_MDR_MST	(1 << 10)

#define DAVINCI_I2C_MDR_TRX	(1 << 9)

#define DAVINCI_I2C_MDR_XA	(1 << 8)

#define DAVINCI_I2C_MDR_RM	(1 << 7)

#define DAVINCI_I2C_MDR_IRS	(1 << 5)



#define DAVINCI_I2C_IMR_AAS	(1 << 6)
@@ -112,6 +113,7 @@ struct davinci_i2c_dev { 
	u8			*buf;

	size_t			buf_len;

	int			irq;

	u8			terminate;

	struct i2c_adapter	adapter;

};
@@ -283,20 +285,34 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop) 
		MOD_REG_BIT(w, DAVINCI_I2C_IMR_XRDY, 1);

	davinci_i2c_write_reg(dev, DAVINCI_I2C_IMR_REG, w);



	dev->terminate = 0;

	/* write the data into mode register */

	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag);



	r = wait_for_completion_interruptible_timeout(&dev->cmd_complete,

						      DAVINCI_I2C_TIMEOUT);

	dev->buf_len = 0;

	if (r < 0)

		return r;



	if (r == 0) {

		dev_err(dev->dev, "controller timed out\n");

		i2c_davinci_init(dev);

		dev->buf_len = 0;

		return -ETIMEDOUT;

	}

	if (dev->buf_len) {

		/* This should be 0 if all bytes were transferred

		 * or dev->cmd_err denotes an error.

		 * A signal may have aborted the transfer.

		 */

		if (r >= 0) {

			dev_err(dev->dev, "abnormal termination buf_len=%i\n",

				dev->buf_len);

			r = -EREMOTEIO;

		}

		dev->terminate = 1;

		wmb();

		dev->buf_len = 0;

	}

	if (r < 0)

		return r;



	/* no error */

	if (likely(!dev->cmd_err))
@@ -354,6 +370,27 @@ static u32 i2c_davinci_func(struct i2c_adapter *adap) 
	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);

}



static void terminate_read(struct davinci_i2c_dev *dev)

{

	u16 w = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);

	w |= DAVINCI_I2C_MDR_NACK;

	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, w);



	/* Throw away data */

	davinci_i2c_read_reg(dev, DAVINCI_I2C_DRR_REG);

	if (!dev->terminate)

		dev_err(dev->dev, "RDR IRQ while no data requested\n");

}

static void terminate_write(struct davinci_i2c_dev *dev)

{

	u16 w = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);

	w |= DAVINCI_I2C_MDR_RM | DAVINCI_I2C_MDR_STP;

	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, w);



	if (!dev->terminate)

		dev_err(dev->dev, "TDR IRQ while no data to send\n");

}



/*

 * Interrupt service routine. This gets called whenever an I2C interrupt

 * occurs.
@@ -374,12 +411,15 @@ static irqreturn_t i2c_davinci_isr(int this_irq, void *dev_id) 


		switch (stat) {

		case DAVINCI_I2C_IVR_AL:

			/* Arbitration lost, must retry */

			dev->cmd_err |= DAVINCI_I2C_STR_AL;

			dev->buf_len = 0;

			complete(&dev->cmd_complete);

			break;



		case DAVINCI_I2C_IVR_NACK:

			dev->cmd_err |= DAVINCI_I2C_STR_NACK;

			dev->buf_len = 0;

			complete(&dev->cmd_complete);

			break;
@@ -401,9 +441,10 @@ static irqreturn_t i2c_davinci_isr(int this_irq, void *dev_id) 
				davinci_i2c_write_reg(dev,

					DAVINCI_I2C_STR_REG,

					DAVINCI_I2C_IMR_RRDY);

			} else

				dev_err(dev->dev, "RDR IRQ while no "

					"data requested\n");

			} else {

				/* signal can terminate transfer */

				terminate_read(dev);

			}

			break;



		case DAVINCI_I2C_IVR_XRDY:
@@ -420,9 +461,10 @@ static irqreturn_t i2c_davinci_isr(int this_irq, void *dev_id) 
				davinci_i2c_write_reg(dev,

						      DAVINCI_I2C_IMR_REG,

						      w);

			} else

				dev_err(dev->dev, "TDR IRQ while no data to "

					"send\n");

			} else {

				/* signal can terminate transfer */

				terminate_write(dev);

			}

			break;



		case DAVINCI_I2C_IVR_SCD: