From 83e72dd97a25a831ff270ce4437416943a1e4b36 Mon Sep 17 00:00:00 2001 From: Seth Forshee Date: Fri, 16 Mar 2012 14:41:21 -0500 Subject: apple_bl: Add register/unregister functions Add functions to allow other modules to enable or disable apple_bl. This will be used by the gmux driver to disable apple_bl when the gmux is present, as it is a better and more reliable option for brightness control. Signed-off-by: Seth Forshee Signed-off-by: Matthew Garrett --- drivers/video/backlight/apple_bl.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) (limited to 'drivers/video/backlight/apple_bl.c') diff --git a/drivers/video/backlight/apple_bl.c b/drivers/video/backlight/apple_bl.c index be98d15..a523b25 100644 --- a/drivers/video/backlight/apple_bl.c +++ b/drivers/video/backlight/apple_bl.c @@ -24,6 +24,7 @@ #include #include #include +#include static struct backlight_device *apple_backlight_device; @@ -221,14 +222,32 @@ static struct acpi_driver apple_bl_driver = { }, }; +static atomic_t apple_bl_registered = ATOMIC_INIT(0); + +int apple_bl_register(void) +{ + if (atomic_xchg(&apple_bl_registered, 1) == 0) + return acpi_bus_register_driver(&apple_bl_driver); + + return 0; +} +EXPORT_SYMBOL_GPL(apple_bl_register); + +void apple_bl_unregister(void) +{ + if (atomic_xchg(&apple_bl_registered, 0) == 1) + acpi_bus_unregister_driver(&apple_bl_driver); +} +EXPORT_SYMBOL_GPL(apple_bl_unregister); + static int __init apple_bl_init(void) { - return acpi_bus_register_driver(&apple_bl_driver); + return apple_bl_register(); } static void __exit apple_bl_exit(void) { - acpi_bus_unregister_driver(&apple_bl_driver); + apple_bl_unregister(); } module_init(apple_bl_init); -- cgit v1.1