[PATCH] i2c-iop3xx: Avoid addressing self

Avoid addressing self when sending a slave address. Follows instruction
in Intel 80331/80321 manuals.
Ignoring this worked previously on 80321, but causes a hang on i2cdetect
on 80331.

Signed-off-by: Peter Milne <peter.milne@d-tacq.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 11 insertions, 8 deletions

diff --git a/drivers/i2c/busses/i2c-iop3xx.c b/drivers/i2c/busses/i2c-iop3xx.c
index aca7e1668605..48c56939c861 100644
--- a/drivers/i2c/busses/i2c-iop3xx.c
+++ b/drivers/i2c/busses/i2c-iop3xx.c
@@ -21,6 +21,9 @@
  * - Make it work with IXP46x chips
  * - Cleanup function names, coding style, etc
  *
+ * - writing to slave address causes latchup on iop331.
+ *      fix: driver refuses to address self.
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation, version 2.
@@ -73,12 +76,6 @@ iop3xx_i2c_reset(struct i2c_algo_iop3xx_data *iop3xx_adap)
 } 
 
 static void 
-iop3xx_i2c_set_slave_addr(struct i2c_algo_iop3xx_data *iop3xx_adap)
-{
-        __raw_writel(MYSAR, iop3xx_adap->ioaddr + SAR_OFFSET);
-}
-
-static void 
 iop3xx_i2c_enable(struct i2c_algo_iop3xx_data *iop3xx_adap)
 {
         u32 cr = IOP3XX_ICR_GCD | IOP3XX_ICR_SCLEN | IOP3XX_ICR_UE;
@@ -248,6 +245,13 @@ iop3xx_i2c_send_target_addr(struct i2c_algo_iop3xx_data *iop3xx_adap,
         int status;
         int rc;
 
+        /* avoid writing to my slave address (hangs on 80331),
+         * forbidden in Intel developer manual
+         */
+        if (msg->addr == MYSAR) {
+                return -EBUSY;
+        }
+
         __raw_writel(iic_cook_addr(msg), iop3xx_adap->ioaddr + DBR_OFFSET);
         
         cr &= ~(IOP3XX_ICR_MSTOP | IOP3XX_ICR_NACK);
@@ -498,7 +502,6 @@ iop3xx_i2c_probe(struct platform_device *pdev)
         spin_lock_init(&adapter_data->lock);
 
         iop3xx_i2c_reset(adapter_data);
-        iop3xx_i2c_set_slave_addr(adapter_data);
         iop3xx_i2c_enable(adapter_data);
 
         platform_set_drvdata(pdev, new_adapter);
diff --git a/drivers/i2c/busses/i2c-iop3xx.h b/drivers/i2c/busses/i2c-iop3xx.h
index e46ebaea7b1e..8485861f6a36 100644
--- a/drivers/i2c/busses/i2c-iop3xx.h
+++ b/drivers/i2c/busses/i2c-iop3xx.h
@@ -80,7 +80,7 @@
 #define IOP3XX_GPOD_I2C0        0x00c0  /* clear these bits to enable ch0 */
 #define IOP3XX_GPOD_I2C1        0x0030  /* clear these bits to enable ch1 */
 
-#define MYSAR                   0x02    /* SWAG a suitable slave address */
+#define MYSAR                   0       /* default slave address */
 
 #define I2C_ERR                 321
 #define I2C_ERR_BERR            (I2C_ERR+0)