mxc_i2c: add retries

Retry unexpected hardware errors. This
will not retry a received NAK.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>

diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
index 093a73f1c52dfac9a2cdeb528627346030029154..cbb0fffb85c67f48b014cb7fbe8c703e8a9601a1 100644 (file)
--- a/drivers/i2c/mxc_i2c.c
+++ b/drivers/i2c/mxc_i2c.c
@@ -218,7 +218,7 @@ void i2c_imx_stop(void)
  * Send start signal, chip address and
  * write register address
  */
-static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
+static int i2c_init_transfer_(struct mxc_i2c_regs *i2c_regs,
                uchar chip, uint addr, int alen)
 {
        unsigned int temp;
@@ -235,7 +235,7 @@ static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
        writeb(0, &i2c_regs->i2sr);
        ret = wait_for_sr_state(i2c_regs, ST_BUS_IDLE);
        if (ret < 0)
-               goto exit;
+               return ret;
 
        /* Start I2C transaction */
        temp = readb(&i2c_regs->i2cr);
@@ -244,7 +244,7 @@ static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
 
        ret = wait_for_sr_state(i2c_regs, ST_BUS_BUSY);
        if (ret < 0)
-               goto exit;
+               return ret;
 
        temp |= I2CR_MTX | I2CR_TX_NO_AK;
        writeb(temp, &i2c_regs->i2cr);
@@ -252,18 +252,36 @@ static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
        /* write slave address */
        ret = tx_byte(i2c_regs, chip << 1);
        if (ret < 0)
-               goto exit;
+               return ret;
 
        while (alen--) {
                ret = tx_byte(i2c_regs, (addr >> (alen * 8)) & 0xff);
                if (ret < 0)
-                       goto exit;
+                       return ret;
        }
        return 0;
-exit:
-       i2c_imx_stop();
-       /* Disable I2C controller */
-       writeb(0, &i2c_regs->i2cr);
+}
+
+static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
+               uchar chip, uint addr, int alen)
+{
+       int retry;
+       int ret;
+       for (retry = 0; retry < 3; retry++) {
+               ret = i2c_init_transfer_(i2c_regs, chip, addr, alen);
+               if (ret >= 0)
+                       return 0;
+               i2c_imx_stop();
+               if (ret == -ENODEV)
+                       return ret;
+
+               printf("%s: failed for chip 0x%x retry=%d\n", __func__, chip,
+                               retry);
+               if (ret != -ERESTART)
+                       writeb(0, &i2c_regs->i2cr);     /* Disable controller */
+               udelay(100);
+       }
+       printf("%s: give up i2c_regs=%p\n", __func__, i2c_regs);
        return ret;
 }