ACPI: create notifier chain to get hotkey events to graphics driver

Kernel mode graphics drivers need this ACPI notifier chaine
so that they can get notified upon hotkey events.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/event.c

@@ -109,6 +109,34 @@ static const struct file_operations acpi_system_event_ops = {
 };
 #endif	/* CONFIG_ACPI_PROC_EVENT */
 
+/* ACPI notifier chain */
+BLOCKING_NOTIFIER_HEAD(acpi_chain_head);
+
+int acpi_notifier_call_chain(struct acpi_device *dev, u32 type, u32 data)
+{
+	struct acpi_bus_event event;
+
+	strcpy(event.device_class, dev->pnp.device_class);
+	strcpy(event.bus_id, dev->pnp.bus_id);
+	event.type = type;
+	event.data = data;
+	return (blocking_notifier_call_chain(&acpi_chain_head, 0, (void *)&event)
+                        == NOTIFY_BAD) ? -EINVAL : 0;
+}
+EXPORT_SYMBOL(acpi_notifier_call_chain);
+
+int register_acpi_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&acpi_chain_head, nb);
+}
+EXPORT_SYMBOL(register_acpi_notifier);
+
+int unregister_acpi_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&acpi_chain_head, nb);
+}
+EXPORT_SYMBOL(unregister_acpi_notifier);
+
 #ifdef CONFIG_NET
 static unsigned int acpi_event_seqnum;
 struct acpi_genl_event {

include/acpi/acpi_bus.h

@@ -321,6 +321,9 @@ struct acpi_bus_event {
 
 extern struct kobject *acpi_kobj;
 extern int acpi_bus_generate_netlink_event(const char*, const char*, u8, int);
+extern int acpi_notifier_call_chain(struct acpi_device *, u32, u32);
+extern int register_acpi_notifier(struct notifier_block *);
+extern int unregister_acpi_notifier(struct notifier_block *);
 /*
  * External Functions
  */