[U-Boot] [PATCH v2 1/2] fsl_i2c: generate nine pulses on SCL if the I2C bus is hung

[Chunhe Lan]

When the code detected that the bus is hung (e.g. SDA stuck low),
send 9 pulses on SCL to try to fixup the bus.

Signed-off-by: Zhao Chenhui <chenhui.zhao at freescale.com>
Signed-off-by: Chunhe Lan <Chunhe.Lan at freescale.com>
Cc: Scott Wood <scottwood at freescale.com>
---
 drivers/i2c/fsl_i2c.c |   58 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/fsl_i2c.c b/drivers/i2c/fsl_i2c.c
index 5d7e010..ef0004d 100644
--- a/drivers/i2c/fsl_i2c.c
+++ b/drivers/i2c/fsl_i2c.c
@@ -222,9 +222,50 @@ static unsigned int get_i2c_clock(int bus)
 		return gd->arch.i2c1_clk;	/* I2C1 clock */
 }
 
+static int i2c_fixup(const struct fsl_i2c *dev)
+{
+	const unsigned long long timeout = usec2ticks(CONFIG_I2C_MBB_TIMEOUT);
+	unsigned long long timeval = 0;
+	int ret = -1;
+
+	writeb(I2C_CR_MEN | I2C_CR_MSTA, &dev->cr);
+
+	timeval = get_ticks();
+	while (!(readb(&dev->sr) & I2C_SR_MBB)) {
+		if ((get_ticks() - timeval) > timeout)
+			goto err;
+	}
+
+	if (readb(&dev->sr) & I2C_SR_MAL) {
+		/* SDA is stuck low */
+		writeb(0, &dev->cr);
+		udelay(100);
+		writeb(I2C_CR_MSTA, &dev->cr);
+		writeb(I2C_CR_MEN | I2C_CR_MSTA, &dev->cr);
+	}
+
+	readb(&dev->dr);
+
+	timeval = get_ticks();
+	while (!(readb(&dev->sr) & I2C_SR_MIF)) {
+		if ((get_ticks() - timeval) > timeout)
+			goto err;
+	}
+	ret = 0;
+
+err:
+	writeb(I2C_CR_MEN, &dev->cr);
+	writeb(0, &dev->sr);
+	udelay(100);
+
+	return ret;
+}
+
 void
 i2c_init(int speed, int slaveadd)
 {
+	const unsigned long long timeout = usec2ticks(CONFIG_I2C_MBB_TIMEOUT);
+	unsigned long long timeval;
 	const struct fsl_i2c *dev;
 	unsigned int temp;
 	int bus_num, i;
@@ -252,6 +293,17 @@ i2c_init(int speed, int slaveadd)
 		writeb(slaveadd << 1, &dev->adr);/* write slave address */
 		writeb(0x0, &dev->sr);		/* clear status register */
 		writeb(I2C_CR_MEN, &dev->cr);	/* start I2C controller */
+
+		timeval = get_ticks();
+		while (readb(&dev->sr) & I2C_SR_MBB) {
+			if ((get_ticks() - timeval) < timeout)
+				continue;
+
+			if (i2c_fixup(dev))
+				debug("i2c_init: BUS#%d failed to init\n", i);
+
+			break;
+		}
 	}
 
 #ifdef CONFIG_SYS_I2C_BOARD_LATE_INIT
@@ -412,8 +464,10 @@ i2c_write(u8 dev, uint addr, int alen, u8 *data, int length)
 	int i = -1; /* signal error */
 	u8 *a = (u8*)&addr;
 
-	if (i2c_wait4bus() >= 0
-	    && i2c_write_addr(dev, I2C_WRITE_BIT, 0) != 0
+	if (i2c_wait4bus() < 0)
+		return -1;
+
+	if (i2c_write_addr(dev, I2C_WRITE_BIT, 0) != 0
 	    && __i2c_write(&a[4 - alen], alen) == alen) {
 		i = __i2c_write(data, length);
 	}
-- 
1.7.6.5