Driver core: Add BUS_NOTIFY_BIND_DRIVER

Add BUS_NOTIFY_BIND_DRIVER as a bus notifier event.

For driver binding/unbinding we with this in
place have the following bus notifier events:
 - BUS_NOTIFY_BIND_DRIVER - before ->probe()
 - BUS_NOTIFY_BOUND_DRIVER - after ->probe()
 - BUS_NOTIFY_UNBIND_DRIVER - before ->remove()
 - BUS_NOTIFY_UNBOUND_DRIVER - after ->remove()

The event BUS_NOTIFY_BIND_DRIVER allows bus code
to be notified that ->probe() is about to be called.

Useful for bus code that needs to setup hardware before
the driver gets to run. With this in place platform
drivers can be loaded and unloaded as modules and the
new BIND event allows bus code to control for instance
device clocks that must be enabled before the driver
can be executed.

Without this patch there is no way for the bus code to
get notified that a modular driver is about to be probed.
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/base/dd.c

@@ -51,6 +51,10 @@ static int driver_sysfs_add(struct device *dev)
 {
 	int ret;
 
+	if (dev->bus)
+		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
+					     BUS_NOTIFY_BIND_DRIVER, dev);
+
 	ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 			  kobject_name(&dev->kobj));
 	if (ret == 0) {

include/linux/device.h

@@ -109,10 +109,12 @@ extern int bus_unregister_notifier(struct bus_type *bus,
  */
 #define BUS_NOTIFY_ADD_DEVICE		0x00000001 /* device added */
 #define BUS_NOTIFY_DEL_DEVICE		0x00000002 /* device removed */
-#define BUS_NOTIFY_BOUND_DRIVER		0x00000003 /* driver bound to device */
-#define BUS_NOTIFY_UNBIND_DRIVER	0x00000004 /* driver about to be
+#define BUS_NOTIFY_BIND_DRIVER		0x00000003 /* driver about to be
+						      bound */
+#define BUS_NOTIFY_BOUND_DRIVER		0x00000004 /* driver bound to device */
+#define BUS_NOTIFY_UNBIND_DRIVER	0x00000005 /* driver about to be
 						      unbound */
-#define BUS_NOTIFY_UNBOUND_DRIVER	0x00000005 /* driver is unbound
+#define BUS_NOTIFY_UNBOUND_DRIVER	0x00000006 /* driver is unbound
 						      from the device */
 
 extern struct kset *bus_get_kset(struct bus_type *bus);