driver-core: implement 'sysdev' functionality for regular devices and…

… buses

All sysdev classes and sysdev devices will converted to regular devices
and buses to properly hook userspace into the event processing.

There is no interesting difference between a 'sysdev' and 'device' which
would justify to roll an entire own subsystem with different userspace
export semantics. Userspace relies on events and generic sysfs subsystem
infrastructure from sysdev devices, which are currently not properly
available.

Every converted sysdev class will create a regular device with the class
name in /sys/devices/system and all registered devices will becom a children
of theses devices.

For compatibility reasons, the sysdev class-wide attributes are created
at this parent device. (Do not copy that logic for anything new, subsystem-
wide properties belong to the subsystem, not to some fake parent device
created in /sys/devices.)

Every sysdev driver is implemented as a simple subsystem interface now,
and no longer called a driver.

After all sysdev classes are ported to regular driver core entities, the
sysdev implementation will be entirely removed from the kernel.

Signed-off-by: Kay Sievers <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/base/base.h

@@ -4,7 +4,9 @@
  * struct subsys_private - structure to hold the private to the driver core portions of the bus_type/class structure.
  *
  * @subsys - the struct kset that defines this subsystem
- * @devices_kset - the list of devices associated
+ * @devices_kset - the subsystem's 'devices' directory
+ * @interfaces - list of subsystem interfaces associated
+ * @mutex - protect the devices, and interfaces lists.
  *
  * @drivers_kset - the list of drivers associated
  * @klist_devices - the klist to iterate over the @devices_kset
@@ -14,10 +16,8 @@
  * @bus - pointer back to the struct bus_type that this structure is associated
  *        with.
  *
- * @class_interfaces - list of class_interfaces associated
  * @glue_dirs - "glue" directory to put in-between the parent device to
  *              avoid namespace conflicts
- * @class_mutex - mutex to protect the children, devices, and interfaces lists.
  * @class - pointer back to the struct class that this structure is associated
  *          with.
  *
@@ -28,6 +28,8 @@
 struct subsys_private {
 	struct kset subsys;
 	struct kset *devices_kset;
+	struct list_head interfaces;
+	struct mutex mutex;
 
 	struct kset *drivers_kset;
 	struct klist klist_devices;
@@ -36,9 +38,7 @@ struct subsys_private {
 	unsigned int drivers_autoprobe:1;
 	struct bus_type *bus;
 
-	struct list_head class_interfaces;
 	struct kset glue_dirs;
-	struct mutex class_mutex;
 	struct class *class;
 };
 #define to_subsys_private(obj) container_of(obj, struct subsys_private, subsys.kobj)
@@ -94,7 +94,6 @@ extern int hypervisor_init(void);
 static inline int hypervisor_init(void) { return 0; }
 #endif
 extern int platform_bus_init(void);
-extern int system_bus_init(void);
 extern int cpu_dev_init(void);
 
 extern int bus_add_device(struct device *dev);
@@ -116,6 +115,7 @@ extern char *make_class_name(const char *name, struct kobject *kobj);
 
 extern int devres_release_all(struct device *dev);
 
+/* /sys/devices directory */
 extern struct kset *devices_kset;
 
 #if defined(CONFIG_MODULES) && defined(CONFIG_SYSFS)