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Commit 5915a3db authored by Aaron Lu's avatar Aaron Lu Committed by Rafael J. Wysocki
Browse files

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: default avatarAaron Lu <aaron.lu@intel.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 068aab77

drivers/video/backlight/backlight.c

+31 −0
Original line number Diff line number Diff line
@@ -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;

}

include/linux/backlight.h

+4 −0
Original line number Diff line number Diff line
@@ -100,6 +100,9 @@ struct backlight_device { 
	/* The framebuffer notifier block */

	struct notifier_block fb_notif;



	/* list entry of all registered backlight devices */

	struct list_head entry;



	struct device dev;

};
@@ -123,6 +126,7 @@ extern void devm_backlight_device_unregister(struct device *dev, 
					struct backlight_device *bd);

extern void backlight_force_update(struct backlight_device *bd,

				   enum backlight_update_reason reason);

extern bool backlight_device_registered(enum backlight_type type);



#define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)