/* 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);#elsestatic 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_OFstruct backlight_device *of_find_backlight_by_node(struct device_node *node);#elsestatic 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);#elsestatic inline struct backlight_device *devm_of_find_backlight(struct device *dev){	return NULL;}#endif #endif