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1/* SPDX-License-Identifier: GPL-2.0 */2/*3 * Backlight Lowlevel Control Abstraction4 *5 * Copyright (C) 2003,2004 Hewlett-Packard Company6 *7 */8 9#ifndef _LINUX_BACKLIGHT_H10#define _LINUX_BACKLIGHT_H11 12#include <linux/device.h>13#include <linux/fb.h>14#include <linux/mutex.h>15#include <linux/notifier.h>16#include <linux/types.h>17 18/**19 * enum backlight_update_reason - what method was used to update backlight20 *21 * A driver indicates the method (reason) used for updating the backlight22 * when calling backlight_force_update().23 */24enum backlight_update_reason {25 /**26 * @BACKLIGHT_UPDATE_HOTKEY: The backlight was updated using a hot-key.27 */28 BACKLIGHT_UPDATE_HOTKEY,29 30 /**31 * @BACKLIGHT_UPDATE_SYSFS: The backlight was updated using sysfs.32 */33 BACKLIGHT_UPDATE_SYSFS,34};35 36/**37 * enum backlight_type - the type of backlight control38 *39 * The type of interface used to control the backlight.40 */41enum backlight_type {42 /**43 * @BACKLIGHT_RAW:44 *45 * The backlight is controlled using hardware registers.46 */47 BACKLIGHT_RAW = 1,48 49 /**50 * @BACKLIGHT_PLATFORM:51 *52 * The backlight is controlled using a platform-specific interface.53 */54 BACKLIGHT_PLATFORM,55 56 /**57 * @BACKLIGHT_FIRMWARE:58 *59 * The backlight is controlled using a standard firmware interface.60 */61 BACKLIGHT_FIRMWARE,62 63 /**64 * @BACKLIGHT_TYPE_MAX: Number of entries.65 */66 BACKLIGHT_TYPE_MAX,67};68 69/**70 * enum backlight_notification - the type of notification71 *72 * The notifications that is used for notification sent to the receiver73 * that registered notifications using backlight_register_notifier().74 */75enum backlight_notification {76 /**77 * @BACKLIGHT_REGISTERED: The backlight device is registered.78 */79 BACKLIGHT_REGISTERED,80 81 /**82 * @BACKLIGHT_UNREGISTERED: The backlight revice is unregistered.83 */84 BACKLIGHT_UNREGISTERED,85};86 87/** enum backlight_scale - the type of scale used for brightness values88 *89 * The type of scale used for brightness values.90 */91enum backlight_scale {92 /**93 * @BACKLIGHT_SCALE_UNKNOWN: The scale is unknown.94 */95 BACKLIGHT_SCALE_UNKNOWN = 0,96 97 /**98 * @BACKLIGHT_SCALE_LINEAR: The scale is linear.99 *100 * The linear scale will increase brightness the same for each step.101 */102 BACKLIGHT_SCALE_LINEAR,103 104 /**105 * @BACKLIGHT_SCALE_NON_LINEAR: The scale is not linear.106 *107 * This is often used when the brightness values tries to adjust to108 * the relative perception of the eye demanding a non-linear scale.109 */110 BACKLIGHT_SCALE_NON_LINEAR,111};112 113struct backlight_device;114 115/**116 * struct backlight_ops - backlight operations117 *118 * The backlight operations are specified when the backlight device is registered.119 */120struct backlight_ops {121 /**122 * @options: Configure how operations are called from the core.123 *124 * The options parameter is used to adjust the behaviour of the core.125 * Set BL_CORE_SUSPENDRESUME to get the update_status() operation called126 * upon suspend and resume.127 */128 unsigned int options;129 130#define BL_CORE_SUSPENDRESUME (1 << 0)131 132 /**133 * @update_status: Operation called when properties have changed.134 *135 * Notify the backlight driver some property has changed.136 * The update_status operation is protected by the update_lock.137 *138 * The backlight driver is expected to use backlight_is_blank()139 * to check if the display is blanked and set brightness accordingly.140 * update_status() is called when any of the properties has changed.141 *142 * RETURNS:143 *144 * 0 on success, negative error code if any failure occurred.145 */146 int (*update_status)(struct backlight_device *);147 148 /**149 * @get_brightness: Return the current backlight brightness.150 *151 * The driver may implement this as a readback from the HW.152 * This operation is optional and if not present then the current153 * brightness property value is used.154 *155 * RETURNS:156 *157 * A brightness value which is 0 or a positive number.158 * On failure a negative error code is returned.159 */160 int (*get_brightness)(struct backlight_device *);161 162 /**163 * @controls_device: Check against the display device164 *165 * Check if the backlight controls the given display device. This166 * operation is optional and if not implemented it is assumed that167 * the display is always the one controlled by the backlight.168 *169 * RETURNS:170 *171 * If display_dev is NULL or display_dev matches the device controlled by172 * the backlight, return true. Otherwise return false.173 */174 bool (*controls_device)(struct backlight_device *bd, struct device *display_dev);175};176 177/**178 * struct backlight_properties - backlight properties179 *180 * This structure defines all the properties of a backlight.181 */182struct backlight_properties {183 /**184 * @brightness: The current brightness requested by the user.185 *186 * The backlight core makes sure the range is (0 to max_brightness)187 * when the brightness is set via the sysfs attribute:188 * /sys/class/backlight/<backlight>/brightness.189 *190 * This value can be set in the backlight_properties passed191 * to devm_backlight_device_register() to set a default brightness192 * value.193 */194 int brightness;195 196 /**197 * @max_brightness: The maximum brightness value.198 *199 * This value must be set in the backlight_properties passed to200 * devm_backlight_device_register() and shall not be modified by the201 * driver after registration.202 */203 int max_brightness;204 205 /**206 * @power: The current power mode.207 *208 * User space can configure the power mode using the sysfs209 * attribute: /sys/class/backlight/<backlight>/bl_power210 * When the power property is updated update_status() is called.211 *212 * The possible values are: (0: full on, 4: full off), see213 * BACKLIGHT_POWER constants.214 *215 * When the backlight device is enabled, @power is set to216 * BACKLIGHT_POWER_ON. When the backlight device is disabled,217 * @power is set to BACKLIGHT_POWER_OFF.218 */219 int power;220 221#define BACKLIGHT_POWER_ON (0)222#define BACKLIGHT_POWER_OFF (4)223#define BACKLIGHT_POWER_REDUCED (1) // deprecated; don't use in new code224 225 /**226 * @type: The type of backlight supported.227 *228 * The backlight type allows userspace to make appropriate229 * policy decisions based on the backlight type.230 *231 * This value must be set in the backlight_properties232 * passed to devm_backlight_device_register().233 */234 enum backlight_type type;235 236 /**237 * @state: The state of the backlight core.238 *239 * The state is a bitmask. BL_CORE_FBBLANK is set when the display240 * is expected to be blank. BL_CORE_SUSPENDED is set when the241 * driver is suspended.242 *243 * backlight drivers are expected to use backlight_is_blank()244 * in their update_status() operation rather than reading the245 * state property.246 *247 * The state is maintained by the core and drivers may not modify it.248 */249 unsigned int state;250 251#define BL_CORE_SUSPENDED (1 << 0) /* backlight is suspended */252#define BL_CORE_FBBLANK (1 << 1) /* backlight is under an fb blank event */253 254 /**255 * @scale: The type of the brightness scale.256 */257 enum backlight_scale scale;258};259 260/**261 * struct backlight_device - backlight device data262 *263 * This structure holds all data required by a backlight device.264 */265struct backlight_device {266 /**267 * @props: Backlight properties268 */269 struct backlight_properties props;270 271 /**272 * @update_lock: The lock used when calling the update_status() operation.273 *274 * update_lock is an internal backlight lock that serialise access275 * to the update_status() operation. The backlight core holds the update_lock276 * when calling the update_status() operation. The update_lock shall not277 * be used by backlight drivers.278 */279 struct mutex update_lock;280 281 /**282 * @ops_lock: The lock used around everything related to backlight_ops.283 *284 * ops_lock is an internal backlight lock that protects the ops pointer285 * and is used around all accesses to ops and when the operations are286 * invoked. The ops_lock shall not be used by backlight drivers.287 */288 struct mutex ops_lock;289 290 /**291 * @ops: Pointer to the backlight operations.292 *293 * If ops is NULL, the driver that registered this device has been unloaded,294 * and if class_get_devdata() points to something in the body of that driver,295 * it is also invalid.296 */297 const struct backlight_ops *ops;298 299 /**300 * @fb_notif: The framebuffer notifier block301 */302 struct notifier_block fb_notif;303 304 /**305 * @entry: List entry of all registered backlight devices306 */307 struct list_head entry;308 309 /**310 * @dev: Parent device.311 */312 struct device dev;313 314 /**315 * @fb_bl_on: The state of individual fbdev's.316 *317 * Multiple fbdev's may share one backlight device. The fb_bl_on318 * records the state of the individual fbdev.319 */320 bool fb_bl_on[FB_MAX];321 322 /**323 * @use_count: The number of uses of fb_bl_on.324 */325 int use_count;326};327 328/**329 * backlight_update_status - force an update of the backlight device status330 * @bd: the backlight device331 */332static inline int backlight_update_status(struct backlight_device *bd)333{334 int ret = -ENOENT;335 336 mutex_lock(&bd->update_lock);337 if (bd->ops && bd->ops->update_status)338 ret = bd->ops->update_status(bd);339 mutex_unlock(&bd->update_lock);340 341 return ret;342}343 344/**345 * backlight_enable - Enable backlight346 * @bd: the backlight device to enable347 */348static inline int backlight_enable(struct backlight_device *bd)349{350 if (!bd)351 return 0;352 353 bd->props.power = BACKLIGHT_POWER_ON;354 bd->props.state &= ~BL_CORE_FBBLANK;355 356 return backlight_update_status(bd);357}358 359/**360 * backlight_disable - Disable backlight361 * @bd: the backlight device to disable362 */363static inline int backlight_disable(struct backlight_device *bd)364{365 if (!bd)366 return 0;367 368 bd->props.power = BACKLIGHT_POWER_OFF;369 bd->props.state |= BL_CORE_FBBLANK;370 371 return backlight_update_status(bd);372}373 374/**375 * backlight_is_blank - Return true if display is expected to be blank376 * @bd: the backlight device377 *378 * Display is expected to be blank if any of these is true::379 *380 * 1) if power in not UNBLANK381 * 2) if state indicate BLANK or SUSPENDED382 *383 * Returns true if display is expected to be blank, false otherwise.384 */385static inline bool backlight_is_blank(const struct backlight_device *bd)386{387 return bd->props.power != BACKLIGHT_POWER_ON ||388 bd->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK);389}390 391/**392 * backlight_get_brightness - Returns the current brightness value393 * @bd: the backlight device394 *395 * Returns the current brightness value, taking in consideration the current396 * state. If backlight_is_blank() returns true then return 0 as brightness397 * otherwise return the current brightness property value.398 *399 * Backlight drivers are expected to use this function in their update_status()400 * operation to get the brightness value.401 */402static inline int backlight_get_brightness(const struct backlight_device *bd)403{404 if (backlight_is_blank(bd))405 return 0;406 else407 return bd->props.brightness;408}409 410struct backlight_device *411backlight_device_register(const char *name, struct device *dev, void *devdata,412 const struct backlight_ops *ops,413 const struct backlight_properties *props);414struct backlight_device *415devm_backlight_device_register(struct device *dev, const char *name,416 struct device *parent, void *devdata,417 const struct backlight_ops *ops,418 const struct backlight_properties *props);419void backlight_device_unregister(struct backlight_device *bd);420void devm_backlight_device_unregister(struct device *dev,421 struct backlight_device *bd);422void backlight_force_update(struct backlight_device *bd,423 enum backlight_update_reason reason);424int backlight_register_notifier(struct notifier_block *nb);425int backlight_unregister_notifier(struct notifier_block *nb);426struct backlight_device *backlight_device_get_by_name(const char *name);427struct backlight_device *backlight_device_get_by_type(enum backlight_type type);428int backlight_device_set_brightness(struct backlight_device *bd,429 unsigned long brightness);430 431#define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)432 433/**434 * bl_get_data - access devdata435 * @bl_dev: pointer to backlight device436 *437 * When a backlight device is registered the driver has the possibility438 * to supply a void * devdata. bl_get_data() return a pointer to the439 * devdata.440 *441 * RETURNS:442 *443 * pointer to devdata stored while registering the backlight device.444 */445static inline void * bl_get_data(struct backlight_device *bl_dev)446{447 return dev_get_drvdata(&bl_dev->dev);448}449 450#ifdef CONFIG_OF451struct backlight_device *of_find_backlight_by_node(struct device_node *node);452#else453static inline struct backlight_device *454of_find_backlight_by_node(struct device_node *node)455{456 return NULL;457}458#endif459 460#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)461struct backlight_device *devm_of_find_backlight(struct device *dev);462#else463static inline struct backlight_device *464devm_of_find_backlight(struct device *dev)465{466 return NULL;467}468#endif469 470#endif471