i2c: Clear i2c_adapter.dev on adapter removal

Clear i2c_adapter.dev on adapter removal. This makes it possible to
re-add the adapter at a later point, which some drivers
(i2c-amd756-s4882, i2c-nforce2-s4985) actually do.

This fixes a bug reported by John Stultz here:
http://lkml.org/lkml/2008/7/15/720
and by Ingo Molar there:
http://lkml.org/lkml/2008/7/16/78

Signed-off-by: Jean Delvare <[e-mail]>
Cc: John Stultz <[e-mail]>
Cc: Ingo Molnar <[e-mail]>

drivers/i2c/busses/i2c-amd756-s4882.c

···
 	int i, error;
 	union i2c_smbus_data ioconfig;
 
+	/* Configure the PCA9556 multiplexer */
+	ioconfig.byte = 0x00; /* All I/O to output mode */
+	error = i2c_smbus_xfer(&amd756_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03,
+			       I2C_SMBUS_BYTE_DATA, &ioconfig);
+	if (error) {
+		dev_err(&amd756_smbus.dev, "PCA9556 configuration failed\n");
+		error = -EIO;
+		goto ERROR0;
+	}
+
 	/* Unregister physical bus */
 	error = i2c_del_adapter(&amd756_smbus);
 	if (error) {
···
 	s4882_algo[3].smbus_xfer = amd756_access_virt3;
 	s4882_algo[4].smbus_xfer = amd756_access_virt4;
 
-	/* Configure the PCA9556 multiplexer */
-	ioconfig.byte = 0x00; /* All I/O to output mode */
-	error = amd756_smbus.algo->smbus_xfer(&amd756_smbus, 0x18, 0,
-					      I2C_SMBUS_WRITE, 0x03,
-					      I2C_SMBUS_BYTE_DATA, &ioconfig);
-	if (error) {
-		dev_err(&amd756_smbus.dev, "PCA9556 configuration failed\n");
-		error = -EIO;
-		goto ERROR3;
-	}
-
 	/* Register virtual adapters */
 	for (i = 0; i < 5; i++) {
 		error = i2c_add_adapter(s4882_adapter+i);
 		if (error) {
-			dev_err(&amd756_smbus.dev,
+			printk(KERN_ERR "i2c-amd756-s4882: "
 			       "Virtual adapter %d registration "
 			       "failed, module not inserted\n", i);
 			for (i--; i >= 0; i--)
···
 
 	/* Restore physical bus */
 	if (i2c_add_adapter(&amd756_smbus))
-		dev_err(&amd756_smbus.dev, "Physical bus restoration "
-			"failed\n");
+		printk(KERN_ERR "i2c-amd756-s4882: "
+		       "Physical bus restoration failed\n");
 }
 
 MODULE_AUTHOR("Jean Delvare <[e-mail]>");

drivers/i2c/busses/i2c-nforce2-s4985.c

···
 	int i, error;
 	union i2c_smbus_data ioconfig;
 
+	/* Configure the PCA9556 multiplexer */
+	ioconfig.byte = 0x00; /* All I/O to output mode */
+	error = i2c_smbus_xfer(nforce2_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03,
+			       I2C_SMBUS_BYTE_DATA, &ioconfig);
+	if (error) {
+		dev_err(&nforce2_smbus->dev, "PCA9556 configuration failed\n");
+		error = -EIO;
+		goto ERROR0;
+	}
+
 	/* Unregister physical bus */
 	if (!nforce2_smbus)
 		return -ENODEV;
···
 	s4985_algo[3].smbus_xfer = nforce2_access_virt3;
 	s4985_algo[4].smbus_xfer = nforce2_access_virt4;
 
-	/* Configure the PCA9556 multiplexer */
-	ioconfig.byte = 0x00; /* All I/O to output mode */
-	error = nforce2_smbus->algo->smbus_xfer(nforce2_smbus, 0x18, 0,
-						I2C_SMBUS_WRITE, 0x03,
-						I2C_SMBUS_BYTE_DATA, &ioconfig);
-	if (error) {
-		dev_err(&nforce2_smbus->dev, "PCA9556 configuration failed\n");
-		error = -EIO;
-		goto ERROR3;
-	}
-
 	/* Register virtual adapters */
 	for (i = 0; i < 5; i++) {
 		error = i2c_add_adapter(s4985_adapter + i);
 		if (error) {
-			dev_err(&nforce2_smbus->dev,
-				"Virtual adapter %d registration "
-				"failed, module not inserted\n", i);
+			printk(KERN_ERR "i2c-nforce2-s4985: "
+			       "Virtual adapter %d registration "
+			       "failed, module not inserted\n", i);
 			for (i--; i >= 0; i--)
 				i2c_del_adapter(s4985_adapter + i);
 			goto ERROR3;
···
 
 	/* Restore physical bus */
 	if (i2c_add_adapter(nforce2_smbus))
-		dev_err(&nforce2_smbus->dev, "Physical bus restoration "
-			"failed\n");
+		printk(KERN_ERR "i2c-nforce2-s4985: "
+		       "Physical bus restoration failed\n");
 }
 
 MODULE_AUTHOR("Jean Delvare <[e-mail]>");

drivers/i2c/i2c-core.c

···
 
 	dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name);
 
+	/* Clear the device structure in case this adapter is ever going to be
+	   added again */
+	memset(&adap->dev, 0, sizeof(adap->dev));
+
  out_unlock:
 	mutex_unlock(&core_lock);
 	return res;