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 <khali@linux-fr.org>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>

3 files changed, 32 insertions, 30 deletions

diff --git a/drivers/i2c/busses/i2c-amd756-s4882.c b/drivers/i2c/busses/i2c-amd756-s4882.c
index 2f150e33c74c..72872d1e63ef 100644
--- a/drivers/i2c/busses/i2c-amd756-s4882.c
+++ b/drivers/i2c/busses/i2c-amd756-s4882.c
@@ -155,6 +155,16 @@ static int __init amd756_s4882_init(void)
         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) {
@@ -198,22 +208,11 @@ static int __init amd756_s4882_init(void)
         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--)
@@ -252,8 +251,8 @@ static void __exit amd756_s4882_exit(void)
 
         /* 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 <khali@linux-fr.org>");
diff --git a/drivers/i2c/busses/i2c-nforce2-s4985.c b/drivers/i2c/busses/i2c-nforce2-s4985.c
index 6a8995dfd0bb..d1a4cbcf2aa4 100644
--- a/drivers/i2c/busses/i2c-nforce2-s4985.c
+++ b/drivers/i2c/busses/i2c-nforce2-s4985.c
@@ -150,6 +150,16 @@ static int __init nforce2_s4985_init(void)
         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;
@@ -191,24 +201,13 @@ static int __init nforce2_s4985_init(void)
         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;
@@ -245,8 +244,8 @@ static void __exit nforce2_s4985_exit(void)
 
         /* 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 <khali@linux-fr.org>");
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 0a79f7661017..7608df83d6d1 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -654,6 +654,10 @@ int i2c_del_adapter(struct i2c_adapter *adap)
 
         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;