i2c-cpm: Fix to takeback i2c bus master-ship after a collision

In case of collision on i2c bus the controller which lost bus mastership
stays as a slave for all subsequent transfers. This results in the i2c
controller never writing to the bus for future transactions, resulting
in i2c transfer timeouts.
  This fix checks for a collision on last I2C transaction and sets the
I2COM_MASTER bit for the new transaction.

Signed-off-by: Sachin Surendran <sachin.surendran@alliedtelesis.co.nz>
Signed-off-by: Scott Wood <scottwood@freescale.com>

diff --git a/drivers/i2c/busses/i2c-cpm.c b/drivers/i2c/busses/i2c-cpm.c
index 3823623baa481b5b42251a894d462dc47de115b2..9e6002108720e4169ae771ce6387176217351ebc 100644 (file)
--- a/drivers/i2c/busses/i2c-cpm.c
+++ b/drivers/i2c/busses/i2c-cpm.c
@@ -338,6 +338,14 @@ static int cpm_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
        tptr = 0;
        rptr = 0;
 
+       /*
+        * If there was a collision in the last i2c transaction,
+        * Set I2COM_MASTER as it was cleared during collision.
+        */
+       if (in_be16(&tbdf->cbd_sc) & BD_SC_CL) {
+               out_8(&cpm->i2c_reg->i2com, I2COM_MASTER);
+       }
+
        while (tptr < num) {
                pmsg = &msgs[tptr];
                dev_dbg(&adap->dev, "R: %d T: %d\n", rptr, tptr);