diff options
Diffstat (limited to 'include/linux/backlight.h')
| -rw-r--r-- | include/linux/backlight.h | 399 |
1 files changed, 325 insertions, 74 deletions
diff --git a/include/linux/backlight.h b/include/linux/backlight.h index 56e4580d4f55..614653e07e3a 100644 --- a/include/linux/backlight.h +++ b/include/linux/backlight.h @@ -14,113 +14,336 @@ #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. +/** + * enum backlight_update_reason - what method was used to update backlight * - * Any other use of the locks below is probably wrong. + * A driver indicates the method (reason) used for updating the backlight + * when calling backlight_force_update(). */ - enum backlight_update_reason { + /** + * @BACKLIGHT_UPDATE_HOTKEY: The backlight was updated using a hot-key. + */ BACKLIGHT_UPDATE_HOTKEY, + + /** + * @BACKLIGHT_UPDATE_SYSFS: The backlight was updated using sysfs. + */ BACKLIGHT_UPDATE_SYSFS, }; +/** + * enum backlight_type - the type of backlight control + * + * The type of interface used to control the backlight. + */ enum backlight_type { + /** + * @BACKLIGHT_RAW: + * + * The backlight is controlled using hardware registers. + */ BACKLIGHT_RAW = 1, + + /** + * @BACKLIGHT_PLATFORM: + * + * The backlight is controlled using a platform-specific interface. + */ BACKLIGHT_PLATFORM, + + /** + * @BACKLIGHT_FIRMWARE: + * + * The backlight is controlled using a standard firmware interface. + */ BACKLIGHT_FIRMWARE, + + /** + * @BACKLIGHT_TYPE_MAX: Number of entries. + */ BACKLIGHT_TYPE_MAX, }; +/** + * enum backlight_notification - the type of notification + * + * The notifications that is used for notification sent to the receiver + * that registered notifications using backlight_register_notifier(). + */ enum backlight_notification { + /** + * @BACKLIGHT_REGISTERED: The backlight device is registered. + */ BACKLIGHT_REGISTERED, + + /** + * @BACKLIGHT_UNREGISTERED: The backlight revice is unregistered. + */ BACKLIGHT_UNREGISTERED, }; +/** enum backlight_scale - the type of scale used for brightness values + * + * The type of scale used for brightness values. + */ enum backlight_scale { + /** + * @BACKLIGHT_SCALE_UNKNOWN: The scale is unknown. + */ BACKLIGHT_SCALE_UNKNOWN = 0, + + /** + * @BACKLIGHT_SCALE_LINEAR: The scale is linear. + * + * The linear scale will increase brightness the same for each step. + */ BACKLIGHT_SCALE_LINEAR, + + /** + * @BACKLIGHT_SCALE_NON_LINEAR: The scale is not linear. + * + * This is often used when the brightness values tries to adjust to + * the relative perception of the eye demanding a non-linear scale. + */ BACKLIGHT_SCALE_NON_LINEAR, }; struct backlight_device; struct fb_info; +/** + * struct backlight_ops - backlight operations + * + * The backlight operations are specified when the backlight device is registered. + */ struct backlight_ops { + /** + * @options: Configure how operations are called from the core. + * + * The options parameter is used to adjust the behaviour of the core. + * Set BL_CORE_SUSPENDRESUME to get the update_status() operation called + * upon suspend and resume. + */ unsigned int options; #define BL_CORE_SUSPENDRESUME (1 << 0) - /* Notify the backlight driver some property has changed */ + /** + * @update_status: Operation called when properties have changed. + * + * Notify the backlight driver some property has changed. + * The update_status operation is protected by the update_lock. + * + * The backlight driver is expected to use backlight_is_blank() + * to check if the display is blanked and set brightness accordingly. + * update_status() is called when any of the properties has changed. + * + * RETURNS: + * + * 0 on success, negative error code if any failure occurred. + */ int (*update_status)(struct backlight_device *); - /* Return the current backlight brightness (accounting for power, - fb_blank etc.) */ + + /** + * @get_brightness: Return the current backlight brightness. + * + * The driver may implement this as a readback from the HW. + * This operation is optional and if not present then the current + * brightness property value is used. + * + * RETURNS: + * + * A brightness value which is 0 or a positive number. + * On failure a negative error code is returned. + */ 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 *); + + /** + * @check_fb: Check the framebuffer device. + * + * Check if given framebuffer device is the one bound to this backlight. + * This operation is optional and if not implemented it is assumed that the + * fbdev is always the one bound to the backlight. + * + * RETURNS: + * + * If info is NULL or the info matches the fbdev bound to the backlight return true. + * If info does not match the fbdev bound to the backlight return false. + */ + int (*check_fb)(struct backlight_device *bd, struct fb_info *info); }; -/* This structure defines all the properties of a backlight */ +/** + * struct backlight_properties - backlight properties + * + * This structure defines all the properties of a backlight. + */ struct backlight_properties { - /* Current User requested brightness (0 - max_brightness) */ + /** + * @brightness: The current brightness requested by the user. + * + * The backlight core makes sure the range is (0 to max_brightness) + * when the brightness is set via the sysfs attribute: + * /sys/class/backlight/<backlight>/brightness. + * + * This value can be set in the backlight_properties passed + * to devm_backlight_device_register() to set a default brightness + * value. + */ int brightness; - /* Maximal value for brightness (read-only) */ + + /** + * @max_brightness: The maximum brightness value. + * + * This value must be set in the backlight_properties passed to + * devm_backlight_device_register() and shall not be modified by the + * driver after registration. + */ int max_brightness; - /* Current FB Power mode (0: full on, 1..3: power saving - modes; 4: full off), see FB_BLANK_XXX */ + + /** + * @power: The current power mode. + * + * User space can configure the power mode using the sysfs + * attribute: /sys/class/backlight/<backlight>/bl_power + * When the power property is updated update_status() is called. + * + * The possible values are: (0: full on, 1 to 3: power saving + * modes; 4: full off), see FB_BLANK_XXX. + * + * When the backlight device is enabled @power is set + * to FB_BLANK_UNBLANK. When the backlight device is disabled + * @power is set to FB_BLANK_POWERDOWN. + */ int power; - /* FB Blanking active? (values as for power) */ - /* Due to be removed, please use (state & BL_CORE_FBBLANK) */ + + /** + * @fb_blank: The power state from the FBIOBLANK ioctl. + * + * When the FBIOBLANK ioctl is called @fb_blank is set to the + * blank parameter and the update_status() operation is called. + * + * When the backlight device is enabled @fb_blank is set + * to FB_BLANK_UNBLANK. When the backlight device is disabled + * @fb_blank is set to FB_BLANK_POWERDOWN. + * + * Backlight drivers should avoid using this property. It has been + * replaced by state & BL_CORE_FBLANK (although most drivers should + * use backlight_is_blank() as the preferred means to get the blank + * state). + * + * fb_blank is deprecated and will be removed. + */ int fb_blank; - /* Backlight type */ + + /** + * @type: The type of backlight supported. + * + * The backlight type allows userspace to make appropriate + * policy decisions based on the backlight type. + * + * This value must be set in the backlight_properties + * passed to devm_backlight_device_register(). + */ enum backlight_type type; - /* Flags used to signal drivers of state changes */ + + /** + * @state: The state of the backlight core. + * + * The state is a bitmask. BL_CORE_FBBLANK is set when the display + * is expected to be blank. BL_CORE_SUSPENDED is set when the + * driver is suspended. + * + * backlight drivers are expected to use backlight_is_blank() + * in their update_status() operation rather than reading the + * state property. + * + * The state is maintained by the core and drivers may not modify it. + */ unsigned int state; - /* Type of the brightness scale (linear, non-linear, ...) */ - enum backlight_scale scale; #define BL_CORE_SUSPENDED (1 << 0) /* backlight is suspended */ #define BL_CORE_FBBLANK (1 << 1) /* backlight is under an fb blank event */ + /** + * @scale: The type of the brightness scale. + */ + enum backlight_scale scale; }; +/** + * struct backlight_device - backlight device data + * + * This structure holds all data required by a backlight device. + */ struct backlight_device { - /* Backlight properties */ + /** + * @props: Backlight properties + */ struct backlight_properties props; - /* Serialise access to update_status method */ + /** + * @update_lock: The lock used when calling the update_status() operation. + * + * update_lock is an internal backlight lock that serialise access + * to the update_status() operation. The backlight core holds the update_lock + * when calling the update_status() operation. The update_lock shall not + * be used by backlight drivers. + */ 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. */ + /** + * @ops_lock: The lock used around everything related to backlight_ops. + * + * ops_lock is an internal backlight lock that protects the ops pointer + * and is used around all accesses to ops and when the operations are + * invoked. The ops_lock shall not be used by backlight drivers. + */ struct mutex ops_lock; + + /** + * @ops: Pointer to the backlight operations. + * + * 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. + */ const struct backlight_ops *ops; - /* The framebuffer notifier block */ + /** + * @fb_notif: The framebuffer notifier block + */ struct notifier_block fb_notif; - /* list entry of all registered backlight devices */ + /** + * @entry: List entry of all registered backlight devices + */ struct list_head entry; + /** + * @dev: Parent device. + */ struct device dev; - /* Multiple framebuffers may share one backlight device */ + /** + * @fb_bl_on: The state of individual fbdev's. + * + * Multiple fbdev's may share one backlight device. The fb_bl_on + * records the state of the individual fbdev. + */ bool fb_bl_on[FB_MAX]; + /** + * @use_count: The number of uses of fb_bl_on. + */ int use_count; }; +/** + * backlight_update_status - force an update of the backlight device status + * @bd: the backlight device + */ static inline int backlight_update_status(struct backlight_device *bd) { int ret = -ENOENT; @@ -166,49 +389,83 @@ static inline int backlight_disable(struct backlight_device *bd) } /** - * backlight_put - Drop backlight reference - * @bd: the backlight device to put + * backlight_is_blank - Return true if display is expected to be blank + * @bd: the backlight device + * + * Display is expected to be blank if any of these is true:: + * + * 1) if power in not UNBLANK + * 2) if fb_blank is not UNBLANK + * 3) if state indicate BLANK or SUSPENDED + * + * Returns true if display is expected to be blank, false otherwise. */ -static inline void backlight_put(struct backlight_device *bd) +static inline bool backlight_is_blank(const struct backlight_device *bd) { - if (bd) - put_device(&bd->dev); + return bd->props.power != FB_BLANK_UNBLANK || + bd->props.fb_blank != FB_BLANK_UNBLANK || + bd->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK); } -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); +/** + * backlight_get_brightness - Returns the current brightness value + * @bd: the backlight device + * + * Returns the current brightness value, taking in consideration the current + * state. If backlight_is_blank() returns true then return 0 as brightness + * otherwise return the current brightness property value. + * + * Backlight drivers are expected to use this function in their update_status() + * operation to get the brightness value. + */ +static inline int backlight_get_brightness(const struct backlight_device *bd) +{ + if (backlight_is_blank(bd)) + return 0; + else + return bd->props.brightness; +} + +struct backlight_device * +backlight_device_register(const char *name, struct device *dev, void *devdata, + const struct backlight_ops *ops, + const struct backlight_properties *props); +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); +void backlight_device_unregister(struct backlight_device *bd); +void devm_backlight_device_unregister(struct device *dev, + struct backlight_device *bd); +void backlight_force_update(struct backlight_device *bd, + enum backlight_update_reason reason); +int backlight_register_notifier(struct notifier_block *nb); +int backlight_unregister_notifier(struct notifier_block *nb); struct backlight_device *backlight_device_get_by_name(const char *name); -extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness); +struct backlight_device *backlight_device_get_by_type(enum backlight_type type); +int backlight_device_set_brightness(struct backlight_device *bd, + unsigned long brightness); #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev) +/** + * bl_get_data - access devdata + * @bl_dev: pointer to backlight device + * + * When a backlight device is registered the driver has the possibility + * to supply a void * devdata. bl_get_data() return a pointer to the + * devdata. + * + * RETURNS: + * + * pointer to devdata stored while registering the backlight device. + */ 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); #else @@ -220,14 +477,8 @@ of_find_backlight_by_node(struct device_node *node) #endif #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE) -struct backlight_device *of_find_backlight(struct device *dev); struct backlight_device *devm_of_find_backlight(struct device *dev); #else -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) { |