490 lines
13 KiB
C
490 lines
13 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Backlight Lowlevel Control Abstraction
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*
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* Copyright (C) 2003,2004 Hewlett-Packard Company
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*
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*/
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#ifndef _LINUX_BACKLIGHT_H
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#define _LINUX_BACKLIGHT_H
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#include <linux/device.h>
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#include <linux/fb.h>
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#include <linux/mutex.h>
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#include <linux/notifier.h>
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/**
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* enum backlight_update_reason - what method was used to update backlight
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*
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* A driver indicates the method (reason) used for updating the backlight
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* when calling backlight_force_update().
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*/
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enum backlight_update_reason {
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/**
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* @BACKLIGHT_UPDATE_HOTKEY: The backlight was updated using a hot-key.
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*/
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BACKLIGHT_UPDATE_HOTKEY,
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/**
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* @BACKLIGHT_UPDATE_SYSFS: The backlight was updated using sysfs.
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*/
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BACKLIGHT_UPDATE_SYSFS,
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};
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/**
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* enum backlight_type - the type of backlight control
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*
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* The type of interface used to control the backlight.
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*/
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enum backlight_type {
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/**
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* @BACKLIGHT_RAW:
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*
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* The backlight is controlled using hardware registers.
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*/
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BACKLIGHT_RAW = 1,
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/**
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* @BACKLIGHT_PLATFORM:
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*
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* The backlight is controlled using a platform-specific interface.
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*/
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BACKLIGHT_PLATFORM,
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/**
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* @BACKLIGHT_FIRMWARE:
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*
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* The backlight is controlled using a standard firmware interface.
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*/
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BACKLIGHT_FIRMWARE,
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/**
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* @BACKLIGHT_TYPE_MAX: Number of entries.
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*/
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BACKLIGHT_TYPE_MAX,
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};
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/**
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* enum backlight_notification - the type of notification
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*
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* The notifications that is used for notification sent to the receiver
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* that registered notifications using backlight_register_notifier().
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*/
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enum backlight_notification {
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/**
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* @BACKLIGHT_REGISTERED: The backlight device is registered.
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*/
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BACKLIGHT_REGISTERED,
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/**
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* @BACKLIGHT_UNREGISTERED: The backlight revice is unregistered.
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*/
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BACKLIGHT_UNREGISTERED,
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};
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/** enum backlight_scale - the type of scale used for brightness values
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*
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* The type of scale used for brightness values.
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*/
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enum backlight_scale {
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/**
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* @BACKLIGHT_SCALE_UNKNOWN: The scale is unknown.
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*/
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BACKLIGHT_SCALE_UNKNOWN = 0,
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/**
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* @BACKLIGHT_SCALE_LINEAR: The scale is linear.
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*
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* The linear scale will increase brightness the same for each step.
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*/
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BACKLIGHT_SCALE_LINEAR,
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/**
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* @BACKLIGHT_SCALE_NON_LINEAR: The scale is not linear.
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*
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* This is often used when the brightness values tries to adjust to
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* the relative perception of the eye demanding a non-linear scale.
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*/
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BACKLIGHT_SCALE_NON_LINEAR,
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};
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struct backlight_device;
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struct fb_info;
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/**
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* struct backlight_ops - backlight operations
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*
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* The backlight operations are specified when the backlight device is registered.
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*/
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struct backlight_ops {
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/**
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* @options: Configure how operations are called from the core.
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*
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* The options parameter is used to adjust the behaviour of the core.
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* Set BL_CORE_SUSPENDRESUME to get the update_status() operation called
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* upon suspend and resume.
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*/
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unsigned int options;
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#define BL_CORE_SUSPENDRESUME (1 << 0)
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/**
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* @update_status: Operation called when properties have changed.
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*
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* Notify the backlight driver some property has changed.
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* The update_status operation is protected by the update_lock.
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*
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* The backlight driver is expected to use backlight_is_blank()
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* to check if the display is blanked and set brightness accordingly.
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* update_status() is called when any of the properties has changed.
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*
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* RETURNS:
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*
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* 0 on success, negative error code if any failure occurred.
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*/
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int (*update_status)(struct backlight_device *);
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/**
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* @get_brightness: Return the current backlight brightness.
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*
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* The driver may implement this as a readback from the HW.
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* This operation is optional and if not present then the current
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* brightness property value is used.
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*
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* RETURNS:
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*
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* A brightness value which is 0 or a positive number.
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* On failure a negative error code is returned.
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*/
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int (*get_brightness)(struct backlight_device *);
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/**
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* @check_fb: Check the framebuffer device.
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*
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* Check if given framebuffer device is the one bound to this backlight.
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* This operation is optional and if not implemented it is assumed that the
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* fbdev is always the one bound to the backlight.
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*
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* RETURNS:
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*
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* If info is NULL or the info matches the fbdev bound to the backlight return true.
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* If info does not match the fbdev bound to the backlight return false.
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*/
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int (*check_fb)(struct backlight_device *bd, struct fb_info *info);
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};
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/**
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* struct backlight_properties - backlight properties
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*
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* This structure defines all the properties of a backlight.
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*/
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struct backlight_properties {
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/**
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* @brightness: The current brightness requested by the user.
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*
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* The backlight core makes sure the range is (0 to max_brightness)
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* when the brightness is set via the sysfs attribute:
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* /sys/class/backlight/<backlight>/brightness.
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*
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* This value can be set in the backlight_properties passed
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* to devm_backlight_device_register() to set a default brightness
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* value.
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*/
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int brightness;
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/**
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* @max_brightness: The maximum brightness value.
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*
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* This value must be set in the backlight_properties passed to
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* devm_backlight_device_register() and shall not be modified by the
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* driver after registration.
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*/
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int max_brightness;
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/**
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* @power: The current power mode.
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*
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* User space can configure the power mode using the sysfs
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* attribute: /sys/class/backlight/<backlight>/bl_power
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* When the power property is updated update_status() is called.
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*
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* The possible values are: (0: full on, 1 to 3: power saving
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* modes; 4: full off), see FB_BLANK_XXX.
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*
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* When the backlight device is enabled @power is set
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* to FB_BLANK_UNBLANK. When the backlight device is disabled
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* @power is set to FB_BLANK_POWERDOWN.
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*/
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int power;
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/**
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* @fb_blank: The power state from the FBIOBLANK ioctl.
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*
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* When the FBIOBLANK ioctl is called @fb_blank is set to the
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* blank parameter and the update_status() operation is called.
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*
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* When the backlight device is enabled @fb_blank is set
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* to FB_BLANK_UNBLANK. When the backlight device is disabled
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* @fb_blank is set to FB_BLANK_POWERDOWN.
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*
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* Backlight drivers should avoid using this property. It has been
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* replaced by state & BL_CORE_FBLANK (although most drivers should
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* use backlight_is_blank() as the preferred means to get the blank
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* state).
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*
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* fb_blank is deprecated and will be removed.
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*/
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int fb_blank;
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/**
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* @type: The type of backlight supported.
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*
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* The backlight type allows userspace to make appropriate
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* policy decisions based on the backlight type.
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*
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* This value must be set in the backlight_properties
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* passed to devm_backlight_device_register().
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*/
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enum backlight_type type;
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/**
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* @state: The state of the backlight core.
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*
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* The state is a bitmask. BL_CORE_FBBLANK is set when the display
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* is expected to be blank. BL_CORE_SUSPENDED is set when the
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* driver is suspended.
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*
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* backlight drivers are expected to use backlight_is_blank()
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* in their update_status() operation rather than reading the
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* state property.
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*
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* The state is maintained by the core and drivers may not modify it.
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*/
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unsigned int state;
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#define BL_CORE_SUSPENDED (1 << 0) /* backlight is suspended */
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#define BL_CORE_FBBLANK (1 << 1) /* backlight is under an fb blank event */
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/**
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* @scale: The type of the brightness scale.
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*/
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enum backlight_scale scale;
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};
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/**
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* struct backlight_device - backlight device data
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*
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* This structure holds all data required by a backlight device.
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*/
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struct backlight_device {
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/**
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* @props: Backlight properties
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*/
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struct backlight_properties props;
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/**
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* @update_lock: The lock used when calling the update_status() operation.
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*
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* update_lock is an internal backlight lock that serialise access
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* to the update_status() operation. The backlight core holds the update_lock
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* when calling the update_status() operation. The update_lock shall not
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* be used by backlight drivers.
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*/
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struct mutex update_lock;
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/**
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* @ops_lock: The lock used around everything related to backlight_ops.
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*
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* ops_lock is an internal backlight lock that protects the ops pointer
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* and is used around all accesses to ops and when the operations are
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* invoked. The ops_lock shall not be used by backlight drivers.
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*/
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struct mutex ops_lock;
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/**
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* @ops: Pointer to the backlight operations.
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*
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* If ops is NULL, the driver that registered this device has been unloaded,
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* and if class_get_devdata() points to something in the body of that driver,
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* it is also invalid.
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*/
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const struct backlight_ops *ops;
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/**
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* @fb_notif: The framebuffer notifier block
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*/
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struct notifier_block fb_notif;
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/**
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* @entry: List entry of all registered backlight devices
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*/
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struct list_head entry;
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/**
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* @dev: Parent device.
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*/
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struct device dev;
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/**
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* @fb_bl_on: The state of individual fbdev's.
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*
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* Multiple fbdev's may share one backlight device. The fb_bl_on
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* records the state of the individual fbdev.
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*/
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bool fb_bl_on[FB_MAX];
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/**
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* @use_count: The number of uses of fb_bl_on.
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*/
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int use_count;
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};
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/**
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* backlight_update_status - force an update of the backlight device status
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* @bd: the backlight device
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*/
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static inline int backlight_update_status(struct backlight_device *bd)
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{
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int ret = -ENOENT;
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mutex_lock(&bd->update_lock);
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if (bd->ops && bd->ops->update_status)
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ret = bd->ops->update_status(bd);
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mutex_unlock(&bd->update_lock);
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return ret;
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}
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/**
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* backlight_enable - Enable backlight
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* @bd: the backlight device to enable
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*/
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static inline int backlight_enable(struct backlight_device *bd)
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{
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if (!bd)
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return 0;
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bd->props.power = FB_BLANK_UNBLANK;
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bd->props.fb_blank = FB_BLANK_UNBLANK;
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bd->props.state &= ~BL_CORE_FBBLANK;
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return backlight_update_status(bd);
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}
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/**
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* backlight_disable - Disable backlight
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* @bd: the backlight device to disable
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*/
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static inline int backlight_disable(struct backlight_device *bd)
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{
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if (!bd)
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return 0;
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bd->props.power = FB_BLANK_POWERDOWN;
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bd->props.fb_blank = FB_BLANK_POWERDOWN;
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bd->props.state |= BL_CORE_FBBLANK;
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return backlight_update_status(bd);
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}
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/**
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* backlight_is_blank - Return true if display is expected to be blank
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* @bd: the backlight device
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*
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* Display is expected to be blank if any of these is true::
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*
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* 1) if power in not UNBLANK
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* 2) if fb_blank is not UNBLANK
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* 3) if state indicate BLANK or SUSPENDED
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*
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* Returns true if display is expected to be blank, false otherwise.
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*/
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static inline bool backlight_is_blank(const struct backlight_device *bd)
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{
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return bd->props.power != FB_BLANK_UNBLANK ||
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bd->props.fb_blank != FB_BLANK_UNBLANK ||
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bd->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK);
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}
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/**
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* backlight_get_brightness - Returns the current brightness value
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* @bd: the backlight device
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*
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* Returns the current brightness value, taking in consideration the current
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* state. If backlight_is_blank() returns true then return 0 as brightness
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* otherwise return the current brightness property value.
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*
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* Backlight drivers are expected to use this function in their update_status()
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* operation to get the brightness value.
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*/
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static inline int backlight_get_brightness(const struct backlight_device *bd)
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{
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if (backlight_is_blank(bd))
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return 0;
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else
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return bd->props.brightness;
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}
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struct backlight_device *
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backlight_device_register(const char *name, struct device *dev, void *devdata,
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const struct backlight_ops *ops,
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const struct backlight_properties *props);
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struct backlight_device *
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devm_backlight_device_register(struct device *dev, const char *name,
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struct device *parent, void *devdata,
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const struct backlight_ops *ops,
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const struct backlight_properties *props);
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void backlight_device_unregister(struct backlight_device *bd);
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void devm_backlight_device_unregister(struct device *dev,
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struct backlight_device *bd);
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void backlight_force_update(struct backlight_device *bd,
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enum backlight_update_reason reason);
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int backlight_register_notifier(struct notifier_block *nb);
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int backlight_unregister_notifier(struct notifier_block *nb);
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struct backlight_device *backlight_device_get_by_name(const char *name);
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struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
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int backlight_device_set_brightness(struct backlight_device *bd,
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unsigned long brightness);
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#define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
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/**
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* bl_get_data - access devdata
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* @bl_dev: pointer to backlight device
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*
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* When a backlight device is registered the driver has the possibility
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* to supply a void * devdata. bl_get_data() return a pointer to the
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* devdata.
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*
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* RETURNS:
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*
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* pointer to devdata stored while registering the backlight device.
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*/
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static inline void * bl_get_data(struct backlight_device *bl_dev)
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{
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return dev_get_drvdata(&bl_dev->dev);
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}
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#ifdef CONFIG_OF
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struct backlight_device *of_find_backlight_by_node(struct device_node *node);
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#else
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static inline struct backlight_device *
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of_find_backlight_by_node(struct device_node *node)
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{
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return NULL;
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}
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#endif
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#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
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struct backlight_device *devm_of_find_backlight(struct device *dev);
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#else
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static inline struct backlight_device *
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devm_of_find_backlight(struct device *dev)
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{
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return NULL;
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}
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#endif
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#endif
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