[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.z...@freescale.com>
Signed-off-by: Chunhe Lan <chunhe....@freescale.com>
Cc: Scott Wood <scottw...@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


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