Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-only
2 : /*
3 : * Backlight Lowlevel Control Abstraction
4 : *
5 : * Copyright (C) 2003,2004 Hewlett-Packard Company
6 : *
7 : */
8 :
9 : #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10 :
11 : #include <linux/module.h>
12 : #include <linux/init.h>
13 : #include <linux/device.h>
14 : #include <linux/backlight.h>
15 : #include <linux/notifier.h>
16 : #include <linux/ctype.h>
17 : #include <linux/err.h>
18 : #include <linux/fb.h>
19 : #include <linux/slab.h>
20 :
21 : #ifdef CONFIG_PMAC_BACKLIGHT
22 : #include <asm/backlight.h>
23 : #endif
24 :
25 : /**
26 : * DOC: overview
27 : *
28 : * The backlight core supports implementing backlight drivers.
29 : *
30 : * A backlight driver registers a driver using
31 : * devm_backlight_device_register(). The properties of the backlight
32 : * driver such as type and max_brightness must be specified.
33 : * When the core detect changes in for example brightness or power state
34 : * the update_status() operation is called. The backlight driver shall
35 : * implement this operation and use it to adjust backlight.
36 : *
37 : * Several sysfs attributes are provided by the backlight core::
38 : *
39 : * - brightness R/W, set the requested brightness level
40 : * - actual_brightness RO, the brightness level used by the HW
41 : * - max_brightness RO, the maximum brightness level supported
42 : *
43 : * See Documentation/ABI/stable/sysfs-class-backlight for the full list.
44 : *
45 : * The backlight can be adjusted using the sysfs interface, and
46 : * the backlight driver may also support adjusting backlight using
47 : * a hot-key or some other platform or firmware specific way.
48 : *
49 : * The driver must implement the get_brightness() operation if
50 : * the HW do not support all the levels that can be specified in
51 : * brightness, thus providing user-space access to the actual level
52 : * via the actual_brightness attribute.
53 : *
54 : * When the backlight changes this is reported to user-space using
55 : * an uevent connected to the actual_brightness attribute.
56 : * When brightness is set by platform specific means, for example
57 : * a hot-key to adjust backlight, the driver must notify the backlight
58 : * core that brightness has changed using backlight_force_update().
59 : *
60 : * The backlight driver core receives notifications from fbdev and
61 : * if the event is FB_EVENT_BLANK and if the value of blank, from the
62 : * FBIOBLANK ioctrl, results in a change in the backlight state the
63 : * update_status() operation is called.
64 : */
65 :
66 : static struct list_head backlight_dev_list;
67 : static struct mutex backlight_dev_list_mutex;
68 : static struct blocking_notifier_head backlight_notifier;
69 :
70 : static const char *const backlight_types[] = {
71 : [BACKLIGHT_RAW] = "raw",
72 : [BACKLIGHT_PLATFORM] = "platform",
73 : [BACKLIGHT_FIRMWARE] = "firmware",
74 : };
75 :
76 : static const char *const backlight_scale_types[] = {
77 : [BACKLIGHT_SCALE_UNKNOWN] = "unknown",
78 : [BACKLIGHT_SCALE_LINEAR] = "linear",
79 : [BACKLIGHT_SCALE_NON_LINEAR] = "non-linear",
80 : };
81 :
82 : #if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
83 : defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
84 : /*
85 : * fb_notifier_callback
86 : *
87 : * This callback gets called when something important happens inside a
88 : * framebuffer driver. The backlight core only cares about FB_BLANK_UNBLANK
89 : * which is reported to the driver using backlight_update_status()
90 : * as a state change.
91 : *
92 : * There may be several fbdev's connected to the backlight device,
93 : * in which case they are kept track of. A state change is only reported
94 : * if there is a change in backlight for the specified fbdev.
95 : */
96 : static int fb_notifier_callback(struct notifier_block *self,
97 : unsigned long event, void *data)
98 : {
99 : struct backlight_device *bd;
100 : struct fb_event *evdata = data;
101 : int node = evdata->info->node;
102 : int fb_blank = 0;
103 :
104 : /* If we aren't interested in this event, skip it immediately ... */
105 : if (event != FB_EVENT_BLANK)
106 : return 0;
107 :
108 : bd = container_of(self, struct backlight_device, fb_notif);
109 : mutex_lock(&bd->ops_lock);
110 :
111 : if (!bd->ops)
112 : goto out;
113 : if (bd->ops->check_fb && !bd->ops->check_fb(bd, evdata->info))
114 : goto out;
115 :
116 : fb_blank = *(int *)evdata->data;
117 : if (fb_blank == FB_BLANK_UNBLANK && !bd->fb_bl_on[node]) {
118 : bd->fb_bl_on[node] = true;
119 : if (!bd->use_count++) {
120 : bd->props.state &= ~BL_CORE_FBBLANK;
121 : bd->props.fb_blank = FB_BLANK_UNBLANK;
122 : backlight_update_status(bd);
123 : }
124 : } else if (fb_blank != FB_BLANK_UNBLANK && bd->fb_bl_on[node]) {
125 : bd->fb_bl_on[node] = false;
126 : if (!(--bd->use_count)) {
127 : bd->props.state |= BL_CORE_FBBLANK;
128 : bd->props.fb_blank = fb_blank;
129 : backlight_update_status(bd);
130 : }
131 : }
132 : out:
133 : mutex_unlock(&bd->ops_lock);
134 : return 0;
135 : }
136 :
137 : static int backlight_register_fb(struct backlight_device *bd)
138 : {
139 : memset(&bd->fb_notif, 0, sizeof(bd->fb_notif));
140 : bd->fb_notif.notifier_call = fb_notifier_callback;
141 :
142 : return fb_register_client(&bd->fb_notif);
143 : }
144 :
145 : static void backlight_unregister_fb(struct backlight_device *bd)
146 : {
147 : fb_unregister_client(&bd->fb_notif);
148 : }
149 : #else
150 : static inline int backlight_register_fb(struct backlight_device *bd)
151 : {
152 : return 0;
153 : }
154 :
155 : static inline void backlight_unregister_fb(struct backlight_device *bd)
156 : {
157 : }
158 : #endif /* CONFIG_FB */
159 :
160 0 : static void backlight_generate_event(struct backlight_device *bd,
161 : enum backlight_update_reason reason)
162 : {
163 : char *envp[2];
164 :
165 0 : switch (reason) {
166 : case BACKLIGHT_UPDATE_SYSFS:
167 0 : envp[0] = "SOURCE=sysfs";
168 0 : break;
169 : case BACKLIGHT_UPDATE_HOTKEY:
170 0 : envp[0] = "SOURCE=hotkey";
171 0 : break;
172 : default:
173 0 : envp[0] = "SOURCE=unknown";
174 0 : break;
175 : }
176 0 : envp[1] = NULL;
177 0 : kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp);
178 0 : sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
179 0 : }
180 :
181 0 : static ssize_t bl_power_show(struct device *dev, struct device_attribute *attr,
182 : char *buf)
183 : {
184 0 : struct backlight_device *bd = to_backlight_device(dev);
185 :
186 0 : return sprintf(buf, "%d\n", bd->props.power);
187 : }
188 :
189 0 : static ssize_t bl_power_store(struct device *dev, struct device_attribute *attr,
190 : const char *buf, size_t count)
191 : {
192 : int rc;
193 0 : struct backlight_device *bd = to_backlight_device(dev);
194 : unsigned long power, old_power;
195 :
196 0 : rc = kstrtoul(buf, 0, &power);
197 0 : if (rc)
198 0 : return rc;
199 :
200 0 : rc = -ENXIO;
201 0 : mutex_lock(&bd->ops_lock);
202 0 : if (bd->ops) {
203 : pr_debug("set power to %lu\n", power);
204 0 : if (bd->props.power != power) {
205 0 : old_power = bd->props.power;
206 0 : bd->props.power = power;
207 0 : rc = backlight_update_status(bd);
208 0 : if (rc)
209 0 : bd->props.power = old_power;
210 : else
211 0 : rc = count;
212 : } else {
213 0 : rc = count;
214 : }
215 : }
216 0 : mutex_unlock(&bd->ops_lock);
217 :
218 0 : return rc;
219 : }
220 : static DEVICE_ATTR_RW(bl_power);
221 :
222 0 : static ssize_t brightness_show(struct device *dev,
223 : struct device_attribute *attr, char *buf)
224 : {
225 0 : struct backlight_device *bd = to_backlight_device(dev);
226 :
227 0 : return sprintf(buf, "%d\n", bd->props.brightness);
228 : }
229 :
230 0 : int backlight_device_set_brightness(struct backlight_device *bd,
231 : unsigned long brightness)
232 : {
233 0 : int rc = -ENXIO;
234 :
235 0 : mutex_lock(&bd->ops_lock);
236 0 : if (bd->ops) {
237 0 : if (brightness > bd->props.max_brightness)
238 : rc = -EINVAL;
239 : else {
240 : pr_debug("set brightness to %lu\n", brightness);
241 0 : bd->props.brightness = brightness;
242 0 : rc = backlight_update_status(bd);
243 : }
244 : }
245 0 : mutex_unlock(&bd->ops_lock);
246 :
247 0 : backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);
248 :
249 0 : return rc;
250 : }
251 : EXPORT_SYMBOL(backlight_device_set_brightness);
252 :
253 0 : static ssize_t brightness_store(struct device *dev,
254 : struct device_attribute *attr, const char *buf, size_t count)
255 : {
256 : int rc;
257 0 : struct backlight_device *bd = to_backlight_device(dev);
258 : unsigned long brightness;
259 :
260 0 : rc = kstrtoul(buf, 0, &brightness);
261 0 : if (rc)
262 0 : return rc;
263 :
264 0 : rc = backlight_device_set_brightness(bd, brightness);
265 :
266 0 : return rc ? rc : count;
267 : }
268 : static DEVICE_ATTR_RW(brightness);
269 :
270 0 : static ssize_t type_show(struct device *dev, struct device_attribute *attr,
271 : char *buf)
272 : {
273 0 : struct backlight_device *bd = to_backlight_device(dev);
274 :
275 0 : return sprintf(buf, "%s\n", backlight_types[bd->props.type]);
276 : }
277 : static DEVICE_ATTR_RO(type);
278 :
279 0 : static ssize_t max_brightness_show(struct device *dev,
280 : struct device_attribute *attr, char *buf)
281 : {
282 0 : struct backlight_device *bd = to_backlight_device(dev);
283 :
284 0 : return sprintf(buf, "%d\n", bd->props.max_brightness);
285 : }
286 : static DEVICE_ATTR_RO(max_brightness);
287 :
288 0 : static ssize_t actual_brightness_show(struct device *dev,
289 : struct device_attribute *attr, char *buf)
290 : {
291 0 : int rc = -ENXIO;
292 0 : struct backlight_device *bd = to_backlight_device(dev);
293 :
294 0 : mutex_lock(&bd->ops_lock);
295 0 : if (bd->ops && bd->ops->get_brightness) {
296 0 : rc = bd->ops->get_brightness(bd);
297 0 : if (rc >= 0)
298 0 : rc = sprintf(buf, "%d\n", rc);
299 : } else {
300 0 : rc = sprintf(buf, "%d\n", bd->props.brightness);
301 : }
302 0 : mutex_unlock(&bd->ops_lock);
303 :
304 0 : return rc;
305 : }
306 : static DEVICE_ATTR_RO(actual_brightness);
307 :
308 0 : static ssize_t scale_show(struct device *dev,
309 : struct device_attribute *attr, char *buf)
310 : {
311 0 : struct backlight_device *bd = to_backlight_device(dev);
312 :
313 0 : if (WARN_ON(bd->props.scale > BACKLIGHT_SCALE_NON_LINEAR))
314 0 : return sprintf(buf, "unknown\n");
315 :
316 0 : return sprintf(buf, "%s\n", backlight_scale_types[bd->props.scale]);
317 : }
318 : static DEVICE_ATTR_RO(scale);
319 :
320 : static struct class *backlight_class;
321 :
322 : #ifdef CONFIG_PM_SLEEP
323 0 : static int backlight_suspend(struct device *dev)
324 : {
325 0 : struct backlight_device *bd = to_backlight_device(dev);
326 :
327 0 : mutex_lock(&bd->ops_lock);
328 0 : if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
329 0 : bd->props.state |= BL_CORE_SUSPENDED;
330 0 : backlight_update_status(bd);
331 : }
332 0 : mutex_unlock(&bd->ops_lock);
333 :
334 0 : return 0;
335 : }
336 :
337 0 : static int backlight_resume(struct device *dev)
338 : {
339 0 : struct backlight_device *bd = to_backlight_device(dev);
340 :
341 0 : mutex_lock(&bd->ops_lock);
342 0 : if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
343 0 : bd->props.state &= ~BL_CORE_SUSPENDED;
344 0 : backlight_update_status(bd);
345 : }
346 0 : mutex_unlock(&bd->ops_lock);
347 :
348 0 : return 0;
349 : }
350 : #endif
351 :
352 : static SIMPLE_DEV_PM_OPS(backlight_class_dev_pm_ops, backlight_suspend,
353 : backlight_resume);
354 :
355 0 : static void bl_device_release(struct device *dev)
356 : {
357 0 : struct backlight_device *bd = to_backlight_device(dev);
358 0 : kfree(bd);
359 0 : }
360 :
361 : static struct attribute *bl_device_attrs[] = {
362 : &dev_attr_bl_power.attr,
363 : &dev_attr_brightness.attr,
364 : &dev_attr_actual_brightness.attr,
365 : &dev_attr_max_brightness.attr,
366 : &dev_attr_scale.attr,
367 : &dev_attr_type.attr,
368 : NULL,
369 : };
370 : ATTRIBUTE_GROUPS(bl_device);
371 :
372 : /**
373 : * backlight_force_update - tell the backlight subsystem that hardware state
374 : * has changed
375 : * @bd: the backlight device to update
376 : * @reason: reason for update
377 : *
378 : * Updates the internal state of the backlight in response to a hardware event,
379 : * and generates an uevent to notify userspace. A backlight driver shall call
380 : * backlight_force_update() when the backlight is changed using, for example,
381 : * a hot-key. The updated brightness is read using get_brightness() and the
382 : * brightness value is reported using an uevent.
383 : */
384 0 : void backlight_force_update(struct backlight_device *bd,
385 : enum backlight_update_reason reason)
386 : {
387 : int brightness;
388 :
389 0 : mutex_lock(&bd->ops_lock);
390 0 : if (bd->ops && bd->ops->get_brightness) {
391 0 : brightness = bd->ops->get_brightness(bd);
392 0 : if (brightness >= 0)
393 0 : bd->props.brightness = brightness;
394 : else
395 0 : dev_err(&bd->dev,
396 : "Could not update brightness from device: %pe\n",
397 : ERR_PTR(brightness));
398 : }
399 0 : mutex_unlock(&bd->ops_lock);
400 0 : backlight_generate_event(bd, reason);
401 0 : }
402 : EXPORT_SYMBOL(backlight_force_update);
403 :
404 : /* deprecated - use devm_backlight_device_register() */
405 0 : struct backlight_device *backlight_device_register(const char *name,
406 : struct device *parent, void *devdata, const struct backlight_ops *ops,
407 : const struct backlight_properties *props)
408 : {
409 : struct backlight_device *new_bd;
410 : int rc;
411 :
412 : pr_debug("backlight_device_register: name=%s\n", name);
413 :
414 0 : new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
415 0 : if (!new_bd)
416 : return ERR_PTR(-ENOMEM);
417 :
418 0 : mutex_init(&new_bd->update_lock);
419 0 : mutex_init(&new_bd->ops_lock);
420 :
421 0 : new_bd->dev.class = backlight_class;
422 0 : new_bd->dev.parent = parent;
423 0 : new_bd->dev.release = bl_device_release;
424 0 : dev_set_name(&new_bd->dev, "%s", name);
425 0 : dev_set_drvdata(&new_bd->dev, devdata);
426 :
427 : /* Set default properties */
428 0 : if (props) {
429 0 : memcpy(&new_bd->props, props,
430 : sizeof(struct backlight_properties));
431 0 : if (props->type <= 0 || props->type >= BACKLIGHT_TYPE_MAX) {
432 0 : WARN(1, "%s: invalid backlight type", name);
433 0 : new_bd->props.type = BACKLIGHT_RAW;
434 : }
435 : } else {
436 0 : new_bd->props.type = BACKLIGHT_RAW;
437 : }
438 :
439 0 : rc = device_register(&new_bd->dev);
440 0 : if (rc) {
441 0 : put_device(&new_bd->dev);
442 0 : return ERR_PTR(rc);
443 : }
444 :
445 0 : rc = backlight_register_fb(new_bd);
446 : if (rc) {
447 : device_unregister(&new_bd->dev);
448 : return ERR_PTR(rc);
449 : }
450 :
451 0 : new_bd->ops = ops;
452 :
453 : #ifdef CONFIG_PMAC_BACKLIGHT
454 : mutex_lock(&pmac_backlight_mutex);
455 : if (!pmac_backlight)
456 : pmac_backlight = new_bd;
457 : mutex_unlock(&pmac_backlight_mutex);
458 : #endif
459 :
460 0 : mutex_lock(&backlight_dev_list_mutex);
461 0 : list_add(&new_bd->entry, &backlight_dev_list);
462 0 : mutex_unlock(&backlight_dev_list_mutex);
463 :
464 0 : blocking_notifier_call_chain(&backlight_notifier,
465 : BACKLIGHT_REGISTERED, new_bd);
466 :
467 0 : return new_bd;
468 : }
469 : EXPORT_SYMBOL(backlight_device_register);
470 :
471 : /** backlight_device_get_by_type - find first backlight device of a type
472 : * @type: the type of backlight device
473 : *
474 : * Look up the first backlight device of the specified type
475 : *
476 : * RETURNS:
477 : *
478 : * Pointer to backlight device if any was found. Otherwise NULL.
479 : */
480 0 : struct backlight_device *backlight_device_get_by_type(enum backlight_type type)
481 : {
482 0 : bool found = false;
483 : struct backlight_device *bd;
484 :
485 0 : mutex_lock(&backlight_dev_list_mutex);
486 0 : list_for_each_entry(bd, &backlight_dev_list, entry) {
487 0 : if (bd->props.type == type) {
488 : found = true;
489 : break;
490 : }
491 : }
492 0 : mutex_unlock(&backlight_dev_list_mutex);
493 :
494 0 : return found ? bd : NULL;
495 : }
496 : EXPORT_SYMBOL(backlight_device_get_by_type);
497 :
498 : /**
499 : * backlight_device_get_by_name - Get backlight device by name
500 : * @name: Device name
501 : *
502 : * This function looks up a backlight device by its name. It obtains a reference
503 : * on the backlight device and it is the caller's responsibility to drop the
504 : * reference by calling backlight_put().
505 : *
506 : * Returns:
507 : * A pointer to the backlight device if found, otherwise NULL.
508 : */
509 0 : struct backlight_device *backlight_device_get_by_name(const char *name)
510 : {
511 : struct device *dev;
512 :
513 0 : dev = class_find_device_by_name(backlight_class, name);
514 :
515 0 : return dev ? to_backlight_device(dev) : NULL;
516 : }
517 : EXPORT_SYMBOL(backlight_device_get_by_name);
518 :
519 : /* deprecated - use devm_backlight_device_unregister() */
520 0 : void backlight_device_unregister(struct backlight_device *bd)
521 : {
522 0 : if (!bd)
523 : return;
524 :
525 0 : mutex_lock(&backlight_dev_list_mutex);
526 0 : list_del(&bd->entry);
527 0 : mutex_unlock(&backlight_dev_list_mutex);
528 :
529 : #ifdef CONFIG_PMAC_BACKLIGHT
530 : mutex_lock(&pmac_backlight_mutex);
531 : if (pmac_backlight == bd)
532 : pmac_backlight = NULL;
533 : mutex_unlock(&pmac_backlight_mutex);
534 : #endif
535 :
536 0 : blocking_notifier_call_chain(&backlight_notifier,
537 : BACKLIGHT_UNREGISTERED, bd);
538 :
539 0 : mutex_lock(&bd->ops_lock);
540 0 : bd->ops = NULL;
541 0 : mutex_unlock(&bd->ops_lock);
542 :
543 0 : backlight_unregister_fb(bd);
544 0 : device_unregister(&bd->dev);
545 : }
546 : EXPORT_SYMBOL(backlight_device_unregister);
547 :
548 0 : static void devm_backlight_device_release(struct device *dev, void *res)
549 : {
550 0 : struct backlight_device *backlight = *(struct backlight_device **)res;
551 :
552 0 : backlight_device_unregister(backlight);
553 0 : }
554 :
555 0 : static int devm_backlight_device_match(struct device *dev, void *res,
556 : void *data)
557 : {
558 0 : struct backlight_device **r = res;
559 :
560 0 : return *r == data;
561 : }
562 :
563 : /**
564 : * backlight_register_notifier - get notified of backlight (un)registration
565 : * @nb: notifier block with the notifier to call on backlight (un)registration
566 : *
567 : * Register a notifier to get notified when backlight devices get registered
568 : * or unregistered.
569 : *
570 : * RETURNS:
571 : *
572 : * 0 on success, otherwise a negative error code
573 : */
574 0 : int backlight_register_notifier(struct notifier_block *nb)
575 : {
576 0 : return blocking_notifier_chain_register(&backlight_notifier, nb);
577 : }
578 : EXPORT_SYMBOL(backlight_register_notifier);
579 :
580 : /**
581 : * backlight_unregister_notifier - unregister a backlight notifier
582 : * @nb: notifier block to unregister
583 : *
584 : * Register a notifier to get notified when backlight devices get registered
585 : * or unregistered.
586 : *
587 : * RETURNS:
588 : *
589 : * 0 on success, otherwise a negative error code
590 : */
591 0 : int backlight_unregister_notifier(struct notifier_block *nb)
592 : {
593 0 : return blocking_notifier_chain_unregister(&backlight_notifier, nb);
594 : }
595 : EXPORT_SYMBOL(backlight_unregister_notifier);
596 :
597 : /**
598 : * devm_backlight_device_register - register a new backlight device
599 : * @dev: the device to register
600 : * @name: the name of the device
601 : * @parent: a pointer to the parent device (often the same as @dev)
602 : * @devdata: an optional pointer to be stored for private driver use
603 : * @ops: the backlight operations structure
604 : * @props: the backlight properties
605 : *
606 : * Creates and registers new backlight device. When a backlight device
607 : * is registered the configuration must be specified in the @props
608 : * parameter. See description of &backlight_properties.
609 : *
610 : * RETURNS:
611 : *
612 : * struct backlight on success, or an ERR_PTR on error
613 : */
614 0 : struct backlight_device *devm_backlight_device_register(struct device *dev,
615 : const char *name, struct device *parent, void *devdata,
616 : const struct backlight_ops *ops,
617 : const struct backlight_properties *props)
618 : {
619 : struct backlight_device **ptr, *backlight;
620 :
621 0 : ptr = devres_alloc(devm_backlight_device_release, sizeof(*ptr),
622 : GFP_KERNEL);
623 0 : if (!ptr)
624 : return ERR_PTR(-ENOMEM);
625 :
626 0 : backlight = backlight_device_register(name, parent, devdata, ops,
627 : props);
628 0 : if (!IS_ERR(backlight)) {
629 0 : *ptr = backlight;
630 0 : devres_add(dev, ptr);
631 : } else {
632 0 : devres_free(ptr);
633 : }
634 :
635 : return backlight;
636 : }
637 : EXPORT_SYMBOL(devm_backlight_device_register);
638 :
639 : /**
640 : * devm_backlight_device_unregister - unregister backlight device
641 : * @dev: the device to unregister
642 : * @bd: the backlight device to unregister
643 : *
644 : * Deallocates a backlight allocated with devm_backlight_device_register().
645 : * Normally this function will not need to be called and the resource management
646 : * code will ensure that the resources are freed.
647 : */
648 0 : void devm_backlight_device_unregister(struct device *dev,
649 : struct backlight_device *bd)
650 : {
651 : int rc;
652 :
653 0 : rc = devres_release(dev, devm_backlight_device_release,
654 : devm_backlight_device_match, bd);
655 0 : WARN_ON(rc);
656 0 : }
657 : EXPORT_SYMBOL(devm_backlight_device_unregister);
658 :
659 : #ifdef CONFIG_OF
660 : static int of_parent_match(struct device *dev, const void *data)
661 : {
662 : return dev->parent && dev->parent->of_node == data;
663 : }
664 :
665 : /**
666 : * of_find_backlight_by_node() - find backlight device by device-tree node
667 : * @node: device-tree node of the backlight device
668 : *
669 : * Returns a pointer to the backlight device corresponding to the given DT
670 : * node or NULL if no such backlight device exists or if the device hasn't
671 : * been probed yet.
672 : *
673 : * This function obtains a reference on the backlight device and it is the
674 : * caller's responsibility to drop the reference by calling put_device() on
675 : * the backlight device's .dev field.
676 : */
677 : struct backlight_device *of_find_backlight_by_node(struct device_node *node)
678 : {
679 : struct device *dev;
680 :
681 : dev = class_find_device(backlight_class, NULL, node, of_parent_match);
682 :
683 : return dev ? to_backlight_device(dev) : NULL;
684 : }
685 : EXPORT_SYMBOL(of_find_backlight_by_node);
686 : #endif
687 :
688 : static struct backlight_device *of_find_backlight(struct device *dev)
689 : {
690 0 : struct backlight_device *bd = NULL;
691 : struct device_node *np;
692 :
693 : if (!dev)
694 : return NULL;
695 :
696 : if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
697 : np = of_parse_phandle(dev->of_node, "backlight", 0);
698 : if (np) {
699 : bd = of_find_backlight_by_node(np);
700 : of_node_put(np);
701 : if (!bd)
702 : return ERR_PTR(-EPROBE_DEFER);
703 : }
704 : }
705 :
706 : return bd;
707 : }
708 :
709 : static void devm_backlight_release(void *data)
710 : {
711 : struct backlight_device *bd = data;
712 :
713 : put_device(&bd->dev);
714 : }
715 :
716 : /**
717 : * devm_of_find_backlight - find backlight for a device
718 : * @dev: the device
719 : *
720 : * This function looks for a property named 'backlight' on the DT node
721 : * connected to @dev and looks up the backlight device. The lookup is
722 : * device managed so the reference to the backlight device is automatically
723 : * dropped on driver detach.
724 : *
725 : * RETURNS:
726 : *
727 : * A pointer to the backlight device if found.
728 : * Error pointer -EPROBE_DEFER if the DT property is set, but no backlight
729 : * device is found. NULL if there's no backlight property.
730 : */
731 0 : struct backlight_device *devm_of_find_backlight(struct device *dev)
732 : {
733 : struct backlight_device *bd;
734 : int ret;
735 :
736 0 : bd = of_find_backlight(dev);
737 0 : if (IS_ERR_OR_NULL(bd))
738 : return bd;
739 : ret = devm_add_action_or_reset(dev, devm_backlight_release, bd);
740 : if (ret)
741 : return ERR_PTR(ret);
742 :
743 : return bd;
744 : }
745 : EXPORT_SYMBOL(devm_of_find_backlight);
746 :
747 0 : static void __exit backlight_class_exit(void)
748 : {
749 0 : class_destroy(backlight_class);
750 0 : }
751 :
752 1 : static int __init backlight_class_init(void)
753 : {
754 1 : backlight_class = class_create(THIS_MODULE, "backlight");
755 2 : if (IS_ERR(backlight_class)) {
756 0 : pr_warn("Unable to create backlight class; errno = %ld\n",
757 : PTR_ERR(backlight_class));
758 0 : return PTR_ERR(backlight_class);
759 : }
760 :
761 1 : backlight_class->dev_groups = bl_device_groups;
762 1 : backlight_class->pm = &backlight_class_dev_pm_ops;
763 1 : INIT_LIST_HEAD(&backlight_dev_list);
764 1 : mutex_init(&backlight_dev_list_mutex);
765 1 : BLOCKING_INIT_NOTIFIER_HEAD(&backlight_notifier);
766 :
767 1 : return 0;
768 : }
769 :
770 : /*
771 : * if this is compiled into the kernel, we need to ensure that the
772 : * class is registered before users of the class try to register lcd's
773 : */
774 : postcore_initcall(backlight_class_init);
775 : module_exit(backlight_class_exit);
776 :
777 : MODULE_LICENSE("GPL");
778 : MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
779 : MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");
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