Convert i2c adapters from class devices to bus devices

@@ -488,6 +488,93 @@ void class_interface_unregister(struct c
 	class_put(parent);
 }
 
+struct class_compat {
+	struct kobject *kobj;
+};
+
+/**
+ * class_compat_register - register a compatibility class
+ * @name: the name of the class
+ *
+ * Compatibility classes are meant as a temporary user-space compatibility
+ * workaround when converting a family of class devices to bus devices.
+ */
+struct class_compat *class_compat_register(const char *name)
+{
+	struct class_compat *cls;
+
+	cls = kmalloc(sizeof(struct class_compat), GFP_KERNEL);
+	if (!cls)
+		return NULL;
+	cls->kobj = kobject_create_and_add(name, &class_kset->kobj);
+	if (!cls->kobj) {
+		kfree(cls);
+		return NULL;
+	}
+	return cls;
+}
+EXPORT_SYMBOL_GPL(class_compat_register);
+
+/**
+ * class_compat_unregister - unregister a compatibility class
+ * @cls: the class to unregister
+ */
+void class_compat_unregister(struct class_compat *cls)
+{
+	kobject_put(cls->kobj);
+	kfree(cls);
+}
+EXPORT_SYMBOL_GPL(class_compat_unregister);
+
+/**
+ * class_compat_create_link - create a compatibility class device link to
+ *			      a bus device
+ * @cls: the compatibility class
+ * @dev: the target bus device
+ * @device_link: an optional device to which a "device" link should be created
+ */
+int class_compat_create_link(struct class_compat *cls, struct device *dev,
+			     struct device *device_link)
+{
+	int error;
+
+	error = sysfs_create_link(cls->kobj, &dev->kobj, dev_name(dev));
+	if (error)
+		return error;
+
+	/*
+	 * Optionally add a "device" link (typically to the parent), as a
+	 * class device would have one and we want to provide as much
+	 * backwards compatibility as possible.
+	 */
+	if (device_link) {
+		error = sysfs_create_link(&dev->kobj, &device_link->kobj,
+					  "device");
+		if (error)
+			sysfs_remove_link(cls->kobj, dev_name(dev));
+	}
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(class_compat_create_link);
+
+/**
+ * class_compat_remove_link - remove a compatibility class device link to
+ *			      a bus device
+ * @cls: the compatibility class
+ * @dev: the target bus device
+ * @device_link: an optional device to which a "device" link was previously
+ * 		 created
+ */
+void class_compat_remove_link(struct class_compat *cls, struct device *dev,
+			      struct device *device_link)
+{
+	if (device_link)
+		sysfs_remove_link(&dev->kobj, "device");
+	sysfs_remove_link(cls->kobj, dev_name(dev));
+}
+EXPORT_SYMBOL_GPL(class_compat_remove_link);
+
 int __init classes_init(void)
 {
 	class_kset = kset_create_and_add("class", NULL, NULL);

@@ -223,6 +223,14 @@ extern void class_unregister(struct clas
 	__class_register(class, &__key);	\
 })
 
+struct class_compat;
+struct class_compat *class_compat_register(const char *name);
+void class_compat_unregister(struct class_compat *cls);
+int class_compat_create_link(struct class_compat *cls, struct device *dev,
+			     struct device *device_link);
+void class_compat_remove_link(struct class_compat *cls, struct device *dev,
+			      struct device *device_link);
+
 extern void class_dev_iter_init(struct class_dev_iter *iter,
 				struct class *class,
 				struct device *start,

@@ -64,9 +64,13 @@ static const struct i2c_device_id *i2c_m
 
 static int i2c_device_match(struct device *dev, struct device_driver *drv)
 {
-	struct i2c_client	*client = to_i2c_client(dev);
-	struct i2c_driver	*driver = to_i2c_driver(drv);
+	struct i2c_client	*client = i2c_verify_client(dev);
+	struct i2c_driver	*driver;
+
+	if (!client)
+		return 0;
 
+	driver = to_i2c_driver(drv);
 	/* match on an id table if there is one */
 	if (driver->id_table)
 		return i2c_match_id(driver->id_table, client) != NULL;

@@ -94,10 +98,14 @@ static int i2c_device_uevent(struct devi
 
 static int i2c_device_probe(struct device *dev)
 {
-	struct i2c_client	*client = to_i2c_client(dev);
-	struct i2c_driver	*driver = to_i2c_driver(dev->driver);
+	struct i2c_client	*client = i2c_verify_client(dev);
+	struct i2c_driver	*driver;
 	int status;
 
+	if (!client)
+		return 0;
+
+	driver = to_i2c_driver(dev->driver);
 	if (!driver->probe || !driver->id_table)
 		return -ENODEV;
 	client->driver = driver;

@@ -114,11 +122,11 @@ static int i2c_device_probe(struct devic
 
 static int i2c_device_remove(struct device *dev)
 {
-	struct i2c_client	*client = to_i2c_client(dev);
+	struct i2c_client	*client = i2c_verify_client(dev);
 	struct i2c_driver	*driver;
 	int			status;
 
-	if (!dev->driver)
+	if (!client || !dev->driver)
 		return 0;
 
 	driver = to_i2c_driver(dev->driver);

@@ -136,37 +144,40 @@ static int i2c_device_remove(struct devi
 
 static void i2c_device_shutdown(struct device *dev)
 {
+	struct i2c_client *client = i2c_verify_client(dev);
 	struct i2c_driver *driver;
 
-	if (!dev->driver)
+	if (!client || !dev->driver)
 		return;
 	driver = to_i2c_driver(dev->driver);
 	if (driver->shutdown)
-		driver->shutdown(to_i2c_client(dev));
+		driver->shutdown(client);
 }
 
 static int i2c_device_suspend(struct device *dev, pm_message_t mesg)
 {
+	struct i2c_client *client = i2c_verify_client(dev);
 	struct i2c_driver *driver;
 
-	if (!dev->driver)
+	if (!client || !dev->driver)
 		return 0;
 	driver = to_i2c_driver(dev->driver);
 	if (!driver->suspend)
 		return 0;
-	return driver->suspend(to_i2c_client(dev), mesg);
+	return driver->suspend(client, mesg);
 }
 
 static int i2c_device_resume(struct device *dev)
 {
+	struct i2c_client *client = i2c_verify_client(dev);
 	struct i2c_driver *driver;
 
-	if (!dev->driver)
+	if (!client || !dev->driver)
 		return 0;
 	driver = to_i2c_driver(dev->driver);
 	if (!driver->resume)
 		return 0;
-	return driver->resume(to_i2c_client(dev));
+	return driver->resume(client);
 }
 
 static void i2c_client_dev_release(struct device *dev)

@@ -188,18 +199,28 @@ show_modalias(struct device *dev, struct
 	return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
 }
 
-static struct device_attribute i2c_dev_attrs[] = {
-	__ATTR(name, S_IRUGO, show_client_name, NULL),
+static DEVICE_ATTR(name, S_IRUGO, show_client_name, NULL);
+static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
+
+static struct attribute *i2c_dev_attrs[] = {
+	&dev_attr_name.attr,
 	/* modalias helps coldplug:  modprobe $(cat .../modalias) */
-	__ATTR(modalias, S_IRUGO, show_modalias, NULL),
-	{ },
+	&dev_attr_modalias.attr,
+	NULL
+};
+
+static struct attribute_group i2c_dev_attr_group = {
+	.attrs		= i2c_dev_attrs,
+};
+
+static struct attribute_group *i2c_dev_attr_groups[] = {
+	&i2c_dev_attr_group,
+	NULL
 };
 
 struct bus_type i2c_bus_type = {
 	.name		= "i2c",
-	.dev_attrs	= i2c_dev_attrs,
 	.match		= i2c_device_match,
-	.uevent		= i2c_device_uevent,
 	.probe		= i2c_device_probe,
 	.remove		= i2c_device_remove,
 	.shutdown	= i2c_device_shutdown,

@@ -208,6 +229,12 @@ struct bus_type i2c_bus_type = {
 };
 EXPORT_SYMBOL_GPL(i2c_bus_type);
 
+static struct device_type i2c_client_type = {
+	.groups		= i2c_dev_attr_groups,
+	.uevent		= i2c_device_uevent,
+	.release	= i2c_client_dev_release,
+};
+
 
 /**
  * i2c_verify_client - return parameter as i2c_client, or NULL

@@ -220,7 +247,7 @@ EXPORT_SYMBOL_GPL(i2c_bus_type);
  */
 struct i2c_client *i2c_verify_client(struct device *dev)
 {
-	return (dev->bus == &i2c_bus_type)
+	return (dev->type == &i2c_client_type)
 			? to_i2c_client(dev)
 			: NULL;
 }

@@ -273,7 +300,7 @@ i2c_new_device(struct i2c_adapter *adap,
 
 	client->dev.parent = &client->adapter->dev;
 	client->dev.bus = &i2c_bus_type;
-	client->dev.release = i2c_client_dev_release;
+	client->dev.type = &i2c_client_type;
 
 	dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
 		     client->addr);

@@ -46,6 +46,7 @@ static DEFINE_MUTEX(core_lock);
 static DEFINE_IDR(i2c_adapter_idr);
 static LIST_HEAD(userspace_devices);
 
+static struct device_type i2c_client_type;
 static int i2c_check_addr(struct i2c_adapter *adapter, int addr);
 static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver);
 

@@ -186,10 +187,10 @@ static void i2c_client_dev_release(struc
 }
 
 static ssize_t
-show_client_name(struct device *dev, struct device_attribute *attr, char *buf)
+show_name(struct device *dev, struct device_attribute *attr, char *buf)
 {
-	struct i2c_client *client = to_i2c_client(dev);
-	return sprintf(buf, "%s\n", client->name);
+	return sprintf(buf, "%s\n", dev->type == &i2c_client_type ?
+		       to_i2c_client(dev)->name : to_i2c_adapter(dev)->name);
 }
 
 static ssize_t

@@ -199,7 +200,7 @@ show_modalias(struct device *dev, struct
 	return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
 }
 
-static DEVICE_ATTR(name, S_IRUGO, show_client_name, NULL);
+static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
 static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
 
 static struct attribute *i2c_dev_attrs[] = {

@@ -395,13 +396,6 @@ static void i2c_adapter_dev_release(stru
 	complete(&adap->dev_released);
 }
 
-static ssize_t
-show_adapter_name(struct device *dev, struct device_attribute *attr, char *buf)
-{
-	struct i2c_adapter *adap = to_i2c_adapter(dev);
-	return sprintf(buf, "%s\n", adap->name);
-}
-
 /*
  * Let users instantiate I2C devices through sysfs. This can be used when
  * platform initialization code doesn't contain the proper data for

@@ -520,17 +514,28 @@ i2c_sysfs_delete_device(struct device *d
 	return res;
 }
 
-static struct device_attribute i2c_adapter_attrs[] = {
-	__ATTR(name, S_IRUGO, show_adapter_name, NULL),
-	__ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device),
-	__ATTR(delete_device, S_IWUSR, NULL, i2c_sysfs_delete_device),
-	{ },
+static DEVICE_ATTR(new_device, S_IWUSR, NULL, i2c_sysfs_new_device);
+static DEVICE_ATTR(delete_device, S_IWUSR, NULL, i2c_sysfs_delete_device);
+
+static struct attribute *i2c_adapter_attrs[] = {
+	&dev_attr_name.attr,
+	&dev_attr_new_device.attr,
+	&dev_attr_delete_device.attr,
+	NULL
+};
+
+static struct attribute_group i2c_adapter_attr_group = {
+	.attrs		= i2c_adapter_attrs,
+};
+
+static struct attribute_group *i2c_adapter_attr_groups[] = {
+	&i2c_adapter_attr_group,
+	NULL
 };
 
-static struct class i2c_adapter_class = {
-	.owner			= THIS_MODULE,
-	.name			= "i2c-adapter",
-	.dev_attrs		= i2c_adapter_attrs,
+static struct device_type i2c_adapter_type = {
+	.groups		= i2c_adapter_attr_groups,
+	.release	= i2c_adapter_dev_release,
 };
 
 static void i2c_scan_static_board_info(struct i2c_adapter *adapter)

@@ -582,8 +587,8 @@ static int i2c_register_adapter(struct i
 		adap->timeout = HZ;
 
 	dev_set_name(&adap->dev, "i2c-%d", adap->nr);
-	adap->dev.release = &i2c_adapter_dev_release;
-	adap->dev.class = &i2c_adapter_class;
+	adap->dev.bus = &i2c_bus_type;
+	adap->dev.type = &i2c_adapter_type;
 	res = device_register(&adap->dev);
 	if (res)
 		goto out_list;

@@ -795,9 +800,13 @@ EXPORT_SYMBOL(i2c_del_adapter);
 
 static int __attach_adapter(struct device *dev, void *data)
 {
-	struct i2c_adapter *adapter = to_i2c_adapter(dev);
+	struct i2c_adapter *adapter;
 	struct i2c_driver *driver = data;
 
+	if (dev->type != &i2c_adapter_type)
+		return 0;
+	adapter = to_i2c_adapter(dev);
+
 	i2c_detect(adapter, driver);
 
 	/* Legacy drivers scan i2c busses directly */

@@ -836,8 +845,7 @@ int i2c_register_driver(struct module *o
 	INIT_LIST_HEAD(&driver->clients);
 	/* Walk the adapters that are already present */
 	mutex_lock(&core_lock);
-	class_for_each_device(&i2c_adapter_class, NULL, driver,
-			      __attach_adapter);
+	bus_for_each_dev(&i2c_bus_type, NULL, driver, __attach_adapter);
 	mutex_unlock(&core_lock);
 
 	return 0;

@@ -846,10 +854,14 @@ EXPORT_SYMBOL(i2c_register_driver);
 
 static int __detach_adapter(struct device *dev, void *data)
 {
-	struct i2c_adapter *adapter = to_i2c_adapter(dev);
+	struct i2c_adapter *adapter;
 	struct i2c_driver *driver = data;
 	struct i2c_client *client, *_n;
 
+	if (dev->type != &i2c_adapter_type)
+		return 0;
+	adapter = to_i2c_adapter(dev);
+
 	/* Remove the devices we created ourselves as the result of hardware
 	 * probing (using a driver's detect method) */
 	list_for_each_entry_safe(client, _n, &driver->clients, detected) {

@@ -877,8 +889,7 @@ static int __detach_adapter(struct devic
 void i2c_del_driver(struct i2c_driver *driver)
 {
 	mutex_lock(&core_lock);
-	class_for_each_device(&i2c_adapter_class, NULL, driver,
-			      __detach_adapter);
+	bus_for_each_dev(&i2c_bus_type, NULL, driver, __detach_adapter);
 	mutex_unlock(&core_lock);
 
 	driver_unregister(&driver->driver);

@@ -967,16 +978,11 @@ static int __init i2c_init(void)
 	retval = bus_register(&i2c_bus_type);
 	if (retval)
 		return retval;
-	retval = class_register(&i2c_adapter_class);
-	if (retval)
-		goto bus_err;
 	retval = i2c_add_driver(&dummy_driver);
 	if (retval)
-		goto class_err;
+		goto bus_err;
 	return 0;
 
-class_err:
-	class_unregister(&i2c_adapter_class);
 bus_err:
 	bus_unregister(&i2c_bus_type);
 	return retval;

@@ -985,7 +991,6 @@ bus_err:
 static void __exit i2c_exit(void)
 {
 	i2c_del_driver(&dummy_driver);
-	class_unregister(&i2c_adapter_class);
 	bus_unregister(&i2c_bus_type);
 }
 

@@ -538,6 +538,10 @@ static struct device_type i2c_adapter_ty
 	.release	= i2c_adapter_dev_release,
 };
 
+#ifdef CONFIG_I2C_COMPAT
+static struct class_compat *i2c_adapter_compat_class;
+#endif
+
 static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
 {
 	struct i2c_devinfo	*devinfo;

@@ -595,6 +599,14 @@ static int i2c_register_adapter(struct i
 
 	dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);
 
+#ifdef CONFIG_I2C_COMPAT
+	res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
+				       adap->dev.parent);
+	if (res)
+		dev_warn(&adap->dev,
+			 "Failed to create compatibility class link\n");
+#endif
+
 	/* create pre-declared device nodes */
 	if (adap->nr < __i2c_first_dynamic_bus_num)
 		i2c_scan_static_board_info(adap);

@@ -773,6 +785,11 @@ int i2c_del_adapter(struct i2c_adapter *
 	   checking the returned value. */
 	res = device_for_each_child(&adap->dev, NULL, __unregister_client);
 
+#ifdef CONFIG_I2C_COMPAT
+	class_compat_remove_link(i2c_adapter_compat_class, &adap->dev,
+				 adap->dev.parent);
+#endif
+
 	/* clean up the sysfs representation */
 	init_completion(&adap->dev_released);
 	device_unregister(&adap->dev);

@@ -978,12 +995,23 @@ static int __init i2c_init(void)
 	retval = bus_register(&i2c_bus_type);
 	if (retval)
 		return retval;
+#ifdef CONFIG_I2C_COMPAT
+	i2c_adapter_compat_class = class_compat_register("i2c-adapter");
+	if (!i2c_adapter_compat_class) {
+		retval = -ENOMEM;
+		goto bus_err;
+	}
+#endif
 	retval = i2c_add_driver(&dummy_driver);
 	if (retval)
-		goto bus_err;
+		goto class_err;
 	return 0;
 
+class_err:
+#ifdef CONFIG_I2C_COMPAT
+	class_compat_unregister(i2c_adapter_compat_class);
 bus_err:
+#endif
 	bus_unregister(&i2c_bus_type);
 	return retval;
 }

@@ -991,6 +1019,9 @@ bus_err:
 static void __exit i2c_exit(void)
 {
 	i2c_del_driver(&dummy_driver);
+#ifdef CONFIG_I2C_COMPAT
+	class_compat_unregister(i2c_adapter_compat_class);
+#endif
 	bus_unregister(&i2c_bus_type);
 }