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 /* 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/fb.h>
 #include <linux/mutex.h>
 #include <linux/notifier.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_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)
 
     /**
      * @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 *);
 
     /**
      * @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);
 };
 
 /**
  * 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, 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_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;
 
     /**
      * @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;
 
     /**
      * @fb_notif: The framebuffer notifier block
      */
     struct notifier_block fb_notif;
 
     /**
      * @entry: List entry of all registered backlight devices
      */
     struct list_head entry;
 
     /**
      * @dev: Parent device.
      */
     struct device dev;
 
     /**
      * @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;
 
     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 = 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_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 bool backlight_is_blank(const struct backlight_device *bd)
 {
     return bd->props.power != FB_BLANK_UNBLANK ||
            bd->props.fb_blank != FB_BLANK_UNBLANK ||
            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);
 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);
 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);
 }
 
 #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

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