diff options
| -rw-r--r-- | drivers/video/backlight/apple_bl.c | 23 | ||||
| -rw-r--r-- | include/linux/apple_bl.h | 26 |
2 files changed, 47 insertions, 2 deletions
diff --git a/drivers/video/backlight/apple_bl.c b/drivers/video/backlight/apple_bl.c index be98d152b7fd..a523b255e124 100644 --- a/drivers/video/backlight/apple_bl.c +++ b/drivers/video/backlight/apple_bl.c @@ -24,6 +24,7 @@ #include <linux/io.h> #include <linux/pci.h> #include <linux/acpi.h> +#include <linux/atomic.h> 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); diff --git a/include/linux/apple_bl.h b/include/linux/apple_bl.h new file mode 100644 index 000000000000..47bedc0eee69 --- /dev/null +++ b/include/linux/apple_bl.h @@ -0,0 +1,26 @@ +/* + * apple_bl exported symbols + */ + +#ifndef _LINUX_APPLE_BL_H +#define _LINUX_APPLE_BL_H + +#ifdef CONFIG_BACKLIGHT_APPLE + +extern int apple_bl_register(void); +extern void apple_bl_unregister(void); + +#else /* !CONFIG_BACKLIGHT_APPLE */ + +static inline int apple_bl_register(void) +{ + return 0; +} + +static inline void apple_bl_unregister(void) +{ +} + +#endif /* !CONFIG_BACKLIGHT_APPLE */ + +#endif /* _LINUX_APPLE_BL_H */ |