/* SPDX-License-Identifier: GPL-2.0 */ /* * Backlight Lowlevel Control Abstraction * * Copyright (C) 2003,2004 Hewlett-Packard Company * */ #ifndef _LINUX_BACKLIGHT_H #define _LINUX_BACKLIGHT_H #include <linux/device.h> #include <linux/mutex.h> #include <linux/types.h> /** * enum backlight_update_reason - what method was used to update backlight * * 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_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 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) /** * @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 *); /** * @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 *); /** * @controls_device: Check against the display device * * Check if the backlight controls the given display device. This * operation is optional and if not implemented it is assumed that * the display is always the one controlled by the backlight. * * RETURNS: * * If display_dev is NULL or display_dev matches the device controlled by * the backlight, return true. Otherwise return false. */ bool (*controls_device)(struct backlight_device *bd, struct device *display_dev); }; /** * struct backlight_properties - backlight properties * * This structure defines all the properties of a backlight. */ struct backlight_properties { /** * @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; /** * @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; /** * @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, 4: full off), see * BACKLIGHT_POWER constants. * * When the backlight device is enabled, @power is set to * BACKLIGHT_POWER_ON. When the backlight device is disabled, * @power is set to BACKLIGHT_POWER_OFF. */ int power; #define BACKLIGHT_POWER_ON (0) #define BACKLIGHT_POWER_OFF (4) #define BACKLIGHT_POWER_REDUCED (1) // deprecated; don't use in new code /** * @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; /** * @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; #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 { /** * @props: Backlight properties */ struct backlight_properties props; /** * @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; /** * @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; /** * @entry: List entry of all registered backlight devices */ struct list_head entry; /** * @dev: Parent device. */ struct device dev; /** * @use_count: The number of unblanked displays. */ 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; mutex_lock(&bd->update_lock); if (bd->ops && bd->ops->update_status) ret = bd->ops->update_status(bd); mutex_unlock(&bd->update_lock); 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 = BACKLIGHT_POWER_ON; 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 = BACKLIGHT_POWER_OFF; bd->props.state |= BL_CORE_FBBLANK; return backlight_update_status(bd); } /** * 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 state indicate BLANK or SUSPENDED * * Returns true if display is expected to be blank, false otherwise. */ static inline bool backlight_is_blank(const struct backlight_device *bd) { return bd->props.power != BACKLIGHT_POWER_ON || bd->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK); } /** * 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); struct backlight_device *backlight_device_get_by_name(const char *name); struct backlight_device *backlight_device_get_by_type(enum backlight_type type); int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness); #if IS_REACHABLE(CONFIG_BACKLIGHT_CLASS_DEVICE) void backlight_notify_blank(struct backlight_device *bd, struct device *display_dev, bool fb_on, bool prev_fb_on); void backlight_notify_blank_all(struct device *display_dev, bool fb_on, bool prev_fb_on); #else static inline void backlight_notify_blank(struct backlight_device *bd, struct device *display_dev, bool fb_on, bool prev_fb_on) { } static inline void backlight_notify_blank_all(struct device *display_dev, bool fb_on, bool prev_fb_on) { } #endif #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); } #ifdef CONFIG_OF struct backlight_device *of_find_backlight_by_node(struct device_node *node); #else static inline struct backlight_device * of_find_backlight_by_node(struct device_node *node) { return NULL; } #endif #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE) struct backlight_device *devm_of_find_backlight(struct device *dev); #else static inline struct backlight_device * devm_of_find_backlight(struct device *dev) { return NULL; } #endif #endif
