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: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/device.h b/include/linux/device.h
index b97a0cf1eb05..7d9da4b4993f 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -483,6 +483,17 @@ extern int device_rename(struct device *dev, char *new_name);
 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
  * for information on use.
  */