i2c: dev: make i2c_dev_class a static const structure

Now that the driver core allows for struct class to be in read-only
memory, move the i2c_dev_class structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at boot time.
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/i2c-dev.c

@@ -636,7 +636,10 @@ static const struct file_operations i2cdev_fops = {
 
 /* ------------------------------------------------------------------------- */
 
-static struct class *i2c_dev_class;
+static const struct class i2c_dev_class = {
+	.name = "i2c-dev",
+	.dev_groups = i2c_groups,
+};
 
 static void i2cdev_dev_release(struct device *dev)
 {
@@ -665,7 +668,7 @@ static int i2cdev_attach_adapter(struct device *dev)
 
 	device_initialize(&i2c_dev->dev);
 	i2c_dev->dev.devt = MKDEV(I2C_MAJOR, adap->nr);
-	i2c_dev->dev.class = i2c_dev_class;
+	i2c_dev->dev.class = &i2c_dev_class;
 	i2c_dev->dev.parent = &adap->dev;
 	i2c_dev->dev.release = i2cdev_dev_release;
 
@@ -751,12 +754,9 @@ static int __init i2c_dev_init(void)
 	if (res)
 		goto out;
 
-	i2c_dev_class = class_create("i2c-dev");
-	if (IS_ERR(i2c_dev_class)) {
-		res = PTR_ERR(i2c_dev_class);
+	res = class_register(&i2c_dev_class);
+	if (res)
 		goto out_unreg_chrdev;
-	}
-	i2c_dev_class->dev_groups = i2c_groups;
 
 	/* Keep track of adapters which will be added or removed later */
 	res = bus_register_notifier(&i2c_bus_type, &i2cdev_notifier);
@@ -769,7 +769,7 @@ static int __init i2c_dev_init(void)
 	return 0;
 
 out_unreg_class:
-	class_destroy(i2c_dev_class);
+	class_unregister(&i2c_dev_class);
 out_unreg_chrdev:
 	unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
 out:
@@ -781,7 +781,7 @@ static void __exit i2c_dev_exit(void)
 {
 	bus_unregister_notifier(&i2c_bus_type, &i2cdev_notifier);
 	i2c_for_each_dev(NULL, i2c_dev_detach_adapter);
-	class_destroy(i2c_dev_class);
+	class_unregister(&i2c_dev_class);
 	unregister_chrdev_region(MKDEV(I2C_MAJOR, 0), I2C_MINORS);
 }