blob: 0b5897446dcae36d8d4ee0bf87bf4910b3892a37 [file] [log] [blame]
/* SPDX-License-Identifier: GPL-2.0 */
* Backlight Lowlevel Control Abstraction
* Copyright (C) 2003,2004 Hewlett-Packard Company
#include <linux/device.h>
#include <linux/fb.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
/* Notes on locking:
* backlight_device->ops_lock is an internal backlight lock protecting the
* ops pointer and no code outside the core should need to touch it.
* Access to update_status() is serialised by the update_lock mutex since
* most drivers seem to need this and historically get it wrong.
* Most drivers don't need locking on their get_brightness() method.
* If yours does, you need to implement it in the driver. You can use the
* update_lock mutex if appropriate.
* Any other use of the locks below is probably wrong.
enum backlight_update_reason {
enum backlight_type {
enum backlight_notification {
struct backlight_device;
struct fb_info;
struct backlight_ops {
unsigned int options;
#define BL_CORE_SUSPENDRESUME (1 << 0)
/* Notify the backlight driver some property has changed */
int (*update_status)(struct backlight_device *);
/* Return the current backlight brightness (accounting for power,
fb_blank etc.) */
int (*get_brightness)(struct backlight_device *);
/* Check if given framebuffer device is the one bound to this backlight;
return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */
int (*check_fb)(struct backlight_device *, struct fb_info *);
/* This structure defines all the properties of a backlight */
struct backlight_properties {
/* Current User requested brightness (0 - max_brightness) */
int brightness;
/* Maximal value for brightness (read-only) */
int max_brightness;
/* Current FB Power mode (0: full on, 1..3: power saving
modes; 4: full off), see FB_BLANK_XXX */
int power;
/* FB Blanking active? (values as for power) */
/* Due to be removed, please use (state & BL_CORE_FBBLANK) */
int fb_blank;
/* Backlight type */
enum backlight_type type;
/* Flags used to signal drivers of state changes */
unsigned int state;
#define BL_CORE_SUSPENDED (1 << 0) /* backlight is suspended */
#define BL_CORE_FBBLANK (1 << 1) /* backlight is under an fb blank event */
struct backlight_device {
/* Backlight properties */
struct backlight_properties props;
/* Serialise access to update_status method */
struct mutex update_lock;
/* This protects the 'ops' field. If 'ops' is NULL, the driver that
registered this device has been unloaded, and if class_get_devdata()
points to something in the body of that driver, it is also invalid. */
struct mutex ops_lock;
const struct backlight_ops *ops;
/* The framebuffer notifier block */
struct notifier_block fb_notif;
/* list entry of all registered backlight devices */
struct list_head entry;
struct device dev;
/* Multiple framebuffers may share one backlight device */
bool fb_bl_on[FB_MAX];
int use_count;
static inline int backlight_update_status(struct backlight_device *bd)
int ret = -ENOENT;
if (bd->ops && bd->ops->update_status)
ret = bd->ops->update_status(bd);
return ret;
* backlight_enable - Enable backlight
* @bd: the backlight device to enable
static inline int backlight_enable(struct backlight_device *bd)
if (!bd)
return 0;
bd->props.power = FB_BLANK_UNBLANK;
bd->props.fb_blank = FB_BLANK_UNBLANK;
bd->props.state &= ~BL_CORE_FBBLANK;
return backlight_update_status(bd);
* backlight_disable - Disable backlight
* @bd: the backlight device to disable
static inline int backlight_disable(struct backlight_device *bd)
if (!bd)
return 0;
bd->props.power = FB_BLANK_POWERDOWN;
bd->props.fb_blank = FB_BLANK_POWERDOWN;
bd->props.state |= BL_CORE_FBBLANK;
return backlight_update_status(bd);
* backlight_put - Drop backlight reference
* @bd: the backlight device to put
static inline void backlight_put(struct backlight_device *bd)
if (bd)
extern struct backlight_device *backlight_device_register(const char *name,
struct device *dev, void *devdata, const struct backlight_ops *ops,
const struct backlight_properties *props);
extern struct backlight_device *devm_backlight_device_register(
struct device *dev, const char *name, struct device *parent,
void *devdata, const struct backlight_ops *ops,
const struct backlight_properties *props);
extern void backlight_device_unregister(struct backlight_device *bd);
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 int backlight_register_notifier(struct notifier_block *nb);
extern int backlight_unregister_notifier(struct notifier_block *nb);
extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness);
#define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
static inline void * bl_get_data(struct backlight_device *bl_dev)
return dev_get_drvdata(&bl_dev->dev);
struct generic_bl_info {
const char *name;
int max_intensity;
int default_intensity;
int limit_mask;
void (*set_bl_intensity)(int intensity);
void (*kick_battery)(void);
#ifdef CONFIG_OF
struct backlight_device *of_find_backlight_by_node(struct device_node *node);
static inline struct backlight_device *
of_find_backlight_by_node(struct device_node *node)
return NULL;
struct backlight_device *of_find_backlight(struct device *dev);
struct backlight_device *devm_of_find_backlight(struct device *dev);
static inline struct backlight_device *of_find_backlight(struct device *dev)
return NULL;
static inline struct backlight_device *
devm_of_find_backlight(struct device *dev)
return NULL;