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Commit 0aa0dc41 authored by Mark McLoughlin's avatar Mark McLoughlin Committed by Greg Kroah-Hartman
Browse files

driver core: add root_device_register() 



Add support for allocating root device objects which group
device objects under /sys/devices directories.

Also add a sysfs 'module' symlink which points to the owner
of the root device object. This symlink will be used in virtio
to allow userspace to determine which virtio bus implementation
a given device is associated with.

[Includes suggestions from Cornelia Huck]

Signed-off-by: default avatarMark McLoughlin <markmc@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 7232800b

drivers/base/core.c

+91 −0
Original line number Original line Diff line number Diff line
@@ -1217,6 +1217,97 @@ EXPORT_SYMBOL_GPL(put_device); 
EXPORT_SYMBOL_GPL(device_create_file);

EXPORT_SYMBOL_GPL(device_create_file);

EXPORT_SYMBOL_GPL(device_remove_file);

EXPORT_SYMBOL_GPL(device_remove_file);





struct root_device

{

	struct device dev;

	struct module *owner;

};



#define to_root_device(dev) container_of(dev, struct root_device, dev)



static void root_device_release(struct device *dev)

{

	kfree(to_root_device(dev));

}



/**

 * __root_device_register - allocate and register a root device

 * @name: root device name

 * @owner: owner module of the root device, usually THIS_MODULE

 *

 * This function allocates a root device and registers it

 * using device_register(). In order to free the returned

 * device, use root_device_unregister().

 *

 * Root devices are dummy devices which allow other devices

 * to be grouped under /sys/devices. Use this function to

 * allocate a root device and then use it as the parent of

 * any device which should appear under /sys/devices/{name}

 *

 * The /sys/devices/{name} directory will also contain a

 * 'module' symlink which points to the @owner directory

 * in sysfs.

 *

 * Note: You probably want to use root_device_register().

 */

struct device *__root_device_register(const char *name, struct module *owner)

{

	struct root_device *root;

	int err = -ENOMEM;



	root = kzalloc(sizeof(struct root_device), GFP_KERNEL);

	if (!root)

		return ERR_PTR(err);



	err = dev_set_name(&root->dev, name);

	if (err) {

		kfree(root);

		return ERR_PTR(err);

	}



	root->dev.release = root_device_release;



	err = device_register(&root->dev);

	if (err) {

		put_device(&root->dev);

		return ERR_PTR(err);

	}



#ifdef CONFIG_MODULE	/* gotta find a "cleaner" way to do this */

	if (owner) {

		struct module_kobject *mk = &owner->mkobj;



		err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");

		if (err) {

			device_unregister(&root->dev);

			return ERR_PTR(err);

		}

		root->owner = owner;

	}

#endif



	return &root->dev;

}

EXPORT_SYMBOL_GPL(__root_device_register);



/**

 * root_device_unregister - unregister and free a root device

 * @root: device going away.

 *

 * This function unregisters and cleans up a device that was created by

 * root_device_register().

 */

void root_device_unregister(struct device *dev)

{

	struct root_device *root = to_root_device(dev);



	if (root->owner)

		sysfs_remove_link(&root->dev.kobj, "module");



	device_unregister(dev);

}

EXPORT_SYMBOL_GPL(root_device_unregister);







static void device_create_release(struct device *dev)

static void device_create_release(struct device *dev)

{

{

include/linux/device.h

+11 −0
Original line number Original line Diff line number Diff line
@@ -482,6 +482,17 @@ extern struct device *device_find_child(struct device *dev, void *data, 
extern int device_rename(struct device *dev, char *new_name);

extern int device_rename(struct device *dev, char *new_name);

extern int device_move(struct device *dev, struct device *new_parent);

extern int device_move(struct device *dev, struct device *new_parent);





/*

 * Root device objects for grouping under /sys/devices

 */

extern struct device *__root_device_register(const char *name,

					     struct module *owner);

static inline struct device *root_device_register(const char *name)

{

	return __root_device_register(name, THIS_MODULE);

}

extern void root_device_unregister(struct device *root);



/*

/*

 * Manual binding of a device to driver. See drivers/base/bus.c

 * Manual binding of a device to driver. See drivers/base/bus.c

 * for information on use.

 * for information on use.