i2c-dev: Use standard bus notification mechanism

Use the standard driver core mechanism to keep track of i2c adapters
present on the system: i2c_for_each_dev and a notifier. This will let
us deprecate and ultimately remove the legacy attach_adapter and
detach_adapter callbacks in i2c_driver.

Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 39 insertions, 21 deletions

diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index cec0f3ba97f..c90ce50b619 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -28,6 +28,8 @@
 
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/device.h>
+#include <linux/notifier.h>
 #include <linux/fs.h>
 #include <linux/slab.h>
 #include <linux/init.h>
@@ -37,16 +39,13 @@
 #include <linux/jiffies.h>
 #include <linux/uaccess.h>
 
-static struct i2c_driver i2cdev_driver;
-
 /*
  * An i2c_dev represents an i2c_adapter ... an I2C or SMBus master, not a
  * slave (i2c_client) with which messages will be exchanged.  It's coupled
  * with a character special file which is accessed by user mode drivers.
  *
  * The list of i2c_dev structures is parallel to the i2c_adapter lists
- * maintained by the driver model, and is updated using notifications
- * delivered to the i2cdev_driver.
+ * maintained by the driver model, and is updated using bus notifications.
  */
 struct i2c_dev {
         struct list_head list;
@@ -491,7 +490,6 @@ static int i2cdev_open(struct inode *inode, struct file *file)
                 return -ENOMEM;
         }
         snprintf(client->name, I2C_NAME_SIZE, "i2c-dev %d", adap->nr);
-        client->driver = &i2cdev_driver;
 
         client->adapter = adap;
         file->private_data = client;
@@ -522,19 +520,18 @@ static const struct file_operations i2cdev_fops = {
 
 /* ------------------------------------------------------------------------- */
 
-/*
- * The legacy "i2cdev_driver" is used primarily to get notifications when
- * I2C adapters are added or removed, so that each one gets an i2c_dev
- * and is thus made available to userspace driver code.
- */
-
 static struct class *i2c_dev_class;
 
-static int i2cdev_attach_adapter(struct i2c_adapter *adap)
+static int i2cdev_attach_adapter(struct device *dev, void *dummy)
 {
+        struct i2c_adapter *adap;
         struct i2c_dev *i2c_dev;
         int res;
 
+        if (dev->type != &i2c_adapter_type)
+                return 0;
+        adap = to_i2c_adapter(dev);
+
         i2c_dev = get_free_i2c_dev(adap);
         if (IS_ERR(i2c_dev))
                 return PTR_ERR(i2c_dev);
@@ -561,10 +558,15 @@ error:
         return res;
 }
 
-static int i2cdev_detach_adapter(struct i2c_adapter *adap)
+static int i2cdev_detach_adapter(struct device *dev, void *dummy)
 {
+        struct i2c_adapter *adap;
         struct i2c_dev *i2c_dev;
 
+        if (dev->type != &i2c_adapter_type)
+                return 0;
+        adap = to_i2c_adapter(dev);
+
         i2c_dev = i2c_dev_get_by_minor(adap->nr);
         if (!i2c_dev) /* attach_adapter must have failed */
                 return 0;
@@ -577,12 +579,23 @@ static int i2cdev_detach_adapter(struct i2c_adapter *adap)
         return 0;
 }
 
-static struct i2c_driver i2cdev_driver = {
-        .driver = {
-                .name   = "dev_driver",
-        },
-        .attach_adapter = i2cdev_attach_adapter,
-        .detach_adapter = i2cdev_detach_adapter,
+int i2cdev_notifier_call(struct notifier_block *nb, unsigned long action,
+                         void *data)
+{
+        struct device *dev = data;
+
+        switch (action) {
+        case BUS_NOTIFY_ADD_DEVICE:
+                return i2cdev_attach_adapter(dev, NULL);
+        case BUS_NOTIFY_DEL_DEVICE:
+                return i2cdev_detach_adapter(dev, NULL);
+        }
+
+        return 0;
+}
+
+static struct notifier_block i2cdev_notifier = {
+        .notifier_call = i2cdev_notifier_call,
 };
 
 /* ------------------------------------------------------------------------- */
@@ -607,10 +620,14 @@ static int __init i2c_dev_init(void)
                 goto out_unreg_chrdev;
         }
 
-        res = i2c_add_driver(&i2cdev_driver);
+        /* Keep track of adapters which will be added or removed later */
+        res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
         if (res)
                 goto out_unreg_class;
 
+        /* Bind to already existing adapters right away */
+        i2c_for_each_dev(NULL, i2cdev_attach_adapter);
+
         return 0;
 
 out_unreg_class:
@@ -624,7 +641,8 @@ out:
 
 static void __exit i2c_dev_exit(void)
 {
-        i2c_del_driver(&i2cdev_driver);
+        bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
+        i2c_for_each_dev(NULL, i2cdev_detach_adapter);
         class_destroy(i2c_dev_class);
         unregister_chrdev(I2C_MAJOR, "i2c");
 }