rfkill: add uevent notifications

Use the notification chains to also send uevents, so that userspace can be
notified of state changes of every rfkill switch.

Userspace should use these events for OSD/status report applications and
rfkill GUI frontends.  HAL might want to broadcast them over DBUS, for
example.  It might be also useful for userspace implementations of
rfkill-input, or to use HAL as the platform driver which promotes rfkill
switch change events into input events (to synchronize all other switches)
when necessary for platforms that lack a convenient platform-specific
kernel module to do it.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Cc: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/rfkill/rfkill.c

@@ -386,12 +386,51 @@ static int rfkill_resume(struct device *dev)
 #define rfkill_resume NULL
 #endif
 
+static int rfkill_blocking_uevent_notifier(struct notifier_block *nb,
+					unsigned long eventid,
+					void *data)
+{
+	struct rfkill *rfkill = (struct rfkill *)data;
+
+	switch (eventid) {
+	case RFKILL_STATE_CHANGED:
+		kobject_uevent(&rfkill->dev.kobj, KOBJ_CHANGE);
+		break;
+	default:
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block rfkill_blocking_uevent_nb = {
+	.notifier_call	= rfkill_blocking_uevent_notifier,
+	.priority	= 0,
+};
+
+static int rfkill_dev_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+	struct rfkill *rfkill = to_rfkill(dev);
+	int error;
+
+	error = add_uevent_var(env, "RFKILL_NAME=%s", rfkill->name);
+	if (error)
+		return error;
+	error = add_uevent_var(env, "RFKILL_TYPE=%s",
+				rfkill_get_type_str(rfkill->type));
+	if (error)
+		return error;
+	error = add_uevent_var(env, "RFKILL_STATE=%d", rfkill->state);
+	return error;
+}
+
 static struct class rfkill_class = {
 	.name		= "rfkill",
 	.dev_release	= rfkill_release,
 	.dev_attrs	= rfkill_dev_attrs,
 	.suspend	= rfkill_suspend,
 	.resume		= rfkill_resume,
+	.dev_uevent	= rfkill_dev_uevent,
 };
 
 static int rfkill_add_switch(struct rfkill *rfkill)
@@ -566,11 +605,14 @@ static int __init rfkill_init(void)
 		return error;
 	}
 
+	register_rfkill_notifier(&rfkill_blocking_uevent_nb);
+
 	return 0;
 }
 
 static void __exit rfkill_exit(void)
 {
+	unregister_rfkill_notifier(&rfkill_blocking_uevent_nb);
 	class_unregister(&rfkill_class);
 }