diff options
| author | Aaron Lu <aaron.lu@intel.com> | 2013-10-11 21:27:43 +0800 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-10-16 01:16:04 +0200 |
| commit | 5915a3db0c3983f1cd5e046bf70086c7d0c686d2 (patch) | |
| tree | d3f56cdf916f71ac50789abf511ee16b6bc55fe6 /drivers | |
| parent | 068aab7766cf968a8ddb86a6d7c6bbed9d61e353 (diff) | |
backlight: introduce backlight_device_registered
Introduce a new API for modules to query if a specific type of backlight
device has been registered. This is useful for some backlight device
provider module (e.g. ACPI video) to know if a native control
interface(e.g. the interface created by i915) is available and then do
things accordingly (e.g. avoid registering its own on Win8 systems).
Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/video/backlight/backlight.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c index 94a403a9717a..5d05555fe841 100644 --- a/drivers/video/backlight/backlight.c +++ b/drivers/video/backlight/backlight.c @@ -21,6 +21,9 @@ #include <asm/backlight.h> #endif +static struct list_head backlight_dev_list; +static struct mutex backlight_dev_list_mutex; + static const char *const backlight_types[] = { [BACKLIGHT_RAW] = "raw", [BACKLIGHT_PLATFORM] = "platform", @@ -349,10 +352,32 @@ struct backlight_device *backlight_device_register(const char *name, mutex_unlock(&pmac_backlight_mutex); #endif + mutex_lock(&backlight_dev_list_mutex); + list_add(&new_bd->entry, &backlight_dev_list); + mutex_unlock(&backlight_dev_list_mutex); + return new_bd; } EXPORT_SYMBOL(backlight_device_register); +bool backlight_device_registered(enum backlight_type type) +{ + bool found = false; + struct backlight_device *bd; + + mutex_lock(&backlight_dev_list_mutex); + list_for_each_entry(bd, &backlight_dev_list, entry) { + if (bd->props.type == type) { + found = true; + break; + } + } + mutex_unlock(&backlight_dev_list_mutex); + + return found; +} +EXPORT_SYMBOL(backlight_device_registered); + /** * backlight_device_unregister - unregisters a backlight device object. * @bd: the backlight device object to be unregistered and freed. @@ -364,6 +389,10 @@ void backlight_device_unregister(struct backlight_device *bd) if (!bd) return; + mutex_lock(&backlight_dev_list_mutex); + list_del(&bd->entry); + mutex_unlock(&backlight_dev_list_mutex); + #ifdef CONFIG_PMAC_BACKLIGHT mutex_lock(&pmac_backlight_mutex); if (pmac_backlight == bd) @@ -499,6 +528,8 @@ static int __init backlight_class_init(void) backlight_class->dev_groups = bl_device_groups; backlight_class->pm = &backlight_class_dev_pm_ops; + INIT_LIST_HEAD(&backlight_dev_list); + mutex_init(&backlight_dev_list_mutex); return 0; } |