1/*
2 * Backlight Lowlevel Control Abstraction
3 *
4 * Copyright (C) 2003,2004 Hewlett-Packard Company
5 *
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/module.h>
11#include <linux/init.h>
12#include <linux/device.h>
13#include <linux/backlight.h>
14#include <linux/notifier.h>
15#include <linux/ctype.h>
16#include <linux/err.h>
17#include <linux/fb.h>
18#include <linux/slab.h>
19
20#ifdef CONFIG_PMAC_BACKLIGHT
21#include <asm/backlight.h>
22#endif
23
24static struct list_head backlight_dev_list;
25static struct mutex backlight_dev_list_mutex;
26static struct blocking_notifier_head backlight_notifier;
27
28static const char *const backlight_types[] = {
29	[BACKLIGHT_RAW] = "raw",
30	[BACKLIGHT_PLATFORM] = "platform",
31	[BACKLIGHT_FIRMWARE] = "firmware",
32};
33
34#if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
35			   defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
36/* This callback gets called when something important happens inside a
37 * framebuffer driver. We're looking if that important event is blanking,
38 * and if it is and necessary, we're switching backlight power as well ...
39 */
40static int fb_notifier_callback(struct notifier_block *self,
41				unsigned long event, void *data)
42{
43	struct backlight_device *bd;
44	struct fb_event *evdata = data;
45	int node = evdata->info->node;
46	int fb_blank = 0;
47
48	/* If we aren't interested in this event, skip it immediately ... */
49	if (event != FB_EVENT_BLANK && event != FB_EVENT_CONBLANK)
50		return 0;
51
52	bd = container_of(self, struct backlight_device, fb_notif);
53	mutex_lock(&bd->ops_lock);
54	if (bd->ops)
55		if (!bd->ops->check_fb ||
56		    bd->ops->check_fb(bd, evdata->info)) {
57			fb_blank = *(int *)evdata->data;
58			if (fb_blank == FB_BLANK_UNBLANK &&
59			    !bd->fb_bl_on[node]) {
60				bd->fb_bl_on[node] = true;
61				if (!bd->use_count++) {
62					bd->props.state &= ~BL_CORE_FBBLANK;
63					bd->props.fb_blank = FB_BLANK_UNBLANK;
64					backlight_update_status(bd);
65				}
66			} else if (fb_blank != FB_BLANK_UNBLANK &&
67				   bd->fb_bl_on[node]) {
68				bd->fb_bl_on[node] = false;
69				if (!(--bd->use_count)) {
70					bd->props.state |= BL_CORE_FBBLANK;
71					bd->props.fb_blank = fb_blank;
72					backlight_update_status(bd);
73				}
74			}
75		}
76	mutex_unlock(&bd->ops_lock);
77	return 0;
78}
79
80static int backlight_register_fb(struct backlight_device *bd)
81{
82	memset(&bd->fb_notif, 0, sizeof(bd->fb_notif));
83	bd->fb_notif.notifier_call = fb_notifier_callback;
84
85	return fb_register_client(&bd->fb_notif);
86}
87
88static void backlight_unregister_fb(struct backlight_device *bd)
89{
90	fb_unregister_client(&bd->fb_notif);
91}
92#else
93static inline int backlight_register_fb(struct backlight_device *bd)
94{
95	return 0;
96}
97
98static inline void backlight_unregister_fb(struct backlight_device *bd)
99{
100}
101#endif /* CONFIG_FB */
102
103static void backlight_generate_event(struct backlight_device *bd,
104				     enum backlight_update_reason reason)
105{
106	char *envp[2];
107
108	switch (reason) {
109	case BACKLIGHT_UPDATE_SYSFS:
110		envp[0] = "SOURCE=sysfs";
111		break;
112	case BACKLIGHT_UPDATE_HOTKEY:
113		envp[0] = "SOURCE=hotkey";
114		break;
115	default:
116		envp[0] = "SOURCE=unknown";
117		break;
118	}
119	envp[1] = NULL;
120	kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp);
121	sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
122}
123
124static ssize_t bl_power_show(struct device *dev, struct device_attribute *attr,
125		char *buf)
126{
127	struct backlight_device *bd = to_backlight_device(dev);
128
129	return sprintf(buf, "%d\n", bd->props.power);
130}
131
132static ssize_t bl_power_store(struct device *dev, struct device_attribute *attr,
133		const char *buf, size_t count)
134{
135	int rc;
136	struct backlight_device *bd = to_backlight_device(dev);
137	unsigned long power;
138
139	rc = kstrtoul(buf, 0, &power);
140	if (rc)
141		return rc;
142
143	rc = -ENXIO;
144	mutex_lock(&bd->ops_lock);
145	if (bd->ops) {
146		pr_debug("set power to %lu\n", power);
147		if (bd->props.power != power) {
148			bd->props.power = power;
149			backlight_update_status(bd);
150		}
151		rc = count;
152	}
153	mutex_unlock(&bd->ops_lock);
154
155	return rc;
156}
157static DEVICE_ATTR_RW(bl_power);
158
159static ssize_t brightness_show(struct device *dev,
160		struct device_attribute *attr, char *buf)
161{
162	struct backlight_device *bd = to_backlight_device(dev);
163
164	return sprintf(buf, "%d\n", bd->props.brightness);
165}
166
167static ssize_t brightness_store(struct device *dev,
168		struct device_attribute *attr, const char *buf, size_t count)
169{
170	int rc;
171	struct backlight_device *bd = to_backlight_device(dev);
172	unsigned long brightness;
173
174	rc = kstrtoul(buf, 0, &brightness);
175	if (rc)
176		return rc;
177
178	rc = -ENXIO;
179
180	mutex_lock(&bd->ops_lock);
181	if (bd->ops) {
182		if (brightness > bd->props.max_brightness)
183			rc = -EINVAL;
184		else {
185			pr_debug("set brightness to %lu\n", brightness);
186			bd->props.brightness = brightness;
187			backlight_update_status(bd);
188			rc = count;
189		}
190	}
191	mutex_unlock(&bd->ops_lock);
192
193	backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);
194
195	return rc;
196}
197static DEVICE_ATTR_RW(brightness);
198
199static ssize_t type_show(struct device *dev, struct device_attribute *attr,
200		char *buf)
201{
202	struct backlight_device *bd = to_backlight_device(dev);
203
204	return sprintf(buf, "%s\n", backlight_types[bd->props.type]);
205}
206static DEVICE_ATTR_RO(type);
207
208static ssize_t max_brightness_show(struct device *dev,
209		struct device_attribute *attr, char *buf)
210{
211	struct backlight_device *bd = to_backlight_device(dev);
212
213	return sprintf(buf, "%d\n", bd->props.max_brightness);
214}
215static DEVICE_ATTR_RO(max_brightness);
216
217static ssize_t actual_brightness_show(struct device *dev,
218		struct device_attribute *attr, char *buf)
219{
220	int rc = -ENXIO;
221	struct backlight_device *bd = to_backlight_device(dev);
222
223	mutex_lock(&bd->ops_lock);
224	if (bd->ops && bd->ops->get_brightness)
225		rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
226	else
227		rc = sprintf(buf, "%d\n", bd->props.brightness);
228	mutex_unlock(&bd->ops_lock);
229
230	return rc;
231}
232static DEVICE_ATTR_RO(actual_brightness);
233
234static struct class *backlight_class;
235
236#ifdef CONFIG_PM_SLEEP
237static int backlight_suspend(struct device *dev)
238{
239	struct backlight_device *bd = to_backlight_device(dev);
240
241	mutex_lock(&bd->ops_lock);
242	if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
243		bd->props.state |= BL_CORE_SUSPENDED;
244		backlight_update_status(bd);
245	}
246	mutex_unlock(&bd->ops_lock);
247
248	return 0;
249}
250
251static int backlight_resume(struct device *dev)
252{
253	struct backlight_device *bd = to_backlight_device(dev);
254
255	mutex_lock(&bd->ops_lock);
256	if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
257		bd->props.state &= ~BL_CORE_SUSPENDED;
258		backlight_update_status(bd);
259	}
260	mutex_unlock(&bd->ops_lock);
261
262	return 0;
263}
264#endif
265
266static SIMPLE_DEV_PM_OPS(backlight_class_dev_pm_ops, backlight_suspend,
267			 backlight_resume);
268
269static void bl_device_release(struct device *dev)
270{
271	struct backlight_device *bd = to_backlight_device(dev);
272	kfree(bd);
273}
274
275static struct attribute *bl_device_attrs[] = {
276	&dev_attr_bl_power.attr,
277	&dev_attr_brightness.attr,
278	&dev_attr_actual_brightness.attr,
279	&dev_attr_max_brightness.attr,
280	&dev_attr_type.attr,
281	NULL,
282};
283ATTRIBUTE_GROUPS(bl_device);
284
285/**
286 * backlight_force_update - tell the backlight subsystem that hardware state
287 *   has changed
288 * @bd: the backlight device to update
289 *
290 * Updates the internal state of the backlight in response to a hardware event,
291 * and generate a uevent to notify userspace
292 */
293void backlight_force_update(struct backlight_device *bd,
294			    enum backlight_update_reason reason)
295{
296	mutex_lock(&bd->ops_lock);
297	if (bd->ops && bd->ops->get_brightness)
298		bd->props.brightness = bd->ops->get_brightness(bd);
299	mutex_unlock(&bd->ops_lock);
300	backlight_generate_event(bd, reason);
301}
302EXPORT_SYMBOL(backlight_force_update);
303
304/**
305 * backlight_device_register - create and register a new object of
306 *   backlight_device class.
307 * @name: the name of the new object(must be the same as the name of the
308 *   respective framebuffer device).
309 * @parent: a pointer to the parent device
310 * @devdata: an optional pointer to be stored for private driver use. The
311 *   methods may retrieve it by using bl_get_data(bd).
312 * @ops: the backlight operations structure.
313 *
314 * Creates and registers new backlight device. Returns either an
315 * ERR_PTR() or a pointer to the newly allocated device.
316 */
317struct backlight_device *backlight_device_register(const char *name,
318	struct device *parent, void *devdata, const struct backlight_ops *ops,
319	const struct backlight_properties *props)
320{
321	struct backlight_device *new_bd;
322	int rc;
323
324	pr_debug("backlight_device_register: name=%s\n", name);
325
326	new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
327	if (!new_bd)
328		return ERR_PTR(-ENOMEM);
329
330	mutex_init(&new_bd->update_lock);
331	mutex_init(&new_bd->ops_lock);
332
333	new_bd->dev.class = backlight_class;
334	new_bd->dev.parent = parent;
335	new_bd->dev.release = bl_device_release;
336	dev_set_name(&new_bd->dev, "%s", name);
337	dev_set_drvdata(&new_bd->dev, devdata);
338
339	/* Set default properties */
340	if (props) {
341		memcpy(&new_bd->props, props,
342		       sizeof(struct backlight_properties));
343		if (props->type <= 0 || props->type >= BACKLIGHT_TYPE_MAX) {
344			WARN(1, "%s: invalid backlight type", name);
345			new_bd->props.type = BACKLIGHT_RAW;
346		}
347	} else {
348		new_bd->props.type = BACKLIGHT_RAW;
349	}
350
351	rc = device_register(&new_bd->dev);
352	if (rc) {
353		put_device(&new_bd->dev);
354		return ERR_PTR(rc);
355	}
356
357	rc = backlight_register_fb(new_bd);
358	if (rc) {
359		device_unregister(&new_bd->dev);
360		return ERR_PTR(rc);
361	}
362
363	new_bd->ops = ops;
364
365#ifdef CONFIG_PMAC_BACKLIGHT
366	mutex_lock(&pmac_backlight_mutex);
367	if (!pmac_backlight)
368		pmac_backlight = new_bd;
369	mutex_unlock(&pmac_backlight_mutex);
370#endif
371
372	mutex_lock(&backlight_dev_list_mutex);
373	list_add(&new_bd->entry, &backlight_dev_list);
374	mutex_unlock(&backlight_dev_list_mutex);
375
376	blocking_notifier_call_chain(&backlight_notifier,
377				     BACKLIGHT_REGISTERED, new_bd);
378
379	return new_bd;
380}
381EXPORT_SYMBOL(backlight_device_register);
382
383bool backlight_device_registered(enum backlight_type type)
384{
385	bool found = false;
386	struct backlight_device *bd;
387
388	mutex_lock(&backlight_dev_list_mutex);
389	list_for_each_entry(bd, &backlight_dev_list, entry) {
390		if (bd->props.type == type) {
391			found = true;
392			break;
393		}
394	}
395	mutex_unlock(&backlight_dev_list_mutex);
396
397	return found;
398}
399EXPORT_SYMBOL(backlight_device_registered);
400
401/**
402 * backlight_device_unregister - unregisters a backlight device object.
403 * @bd: the backlight device object to be unregistered and freed.
404 *
405 * Unregisters a previously registered via backlight_device_register object.
406 */
407void backlight_device_unregister(struct backlight_device *bd)
408{
409	if (!bd)
410		return;
411
412	mutex_lock(&backlight_dev_list_mutex);
413	list_del(&bd->entry);
414	mutex_unlock(&backlight_dev_list_mutex);
415
416#ifdef CONFIG_PMAC_BACKLIGHT
417	mutex_lock(&pmac_backlight_mutex);
418	if (pmac_backlight == bd)
419		pmac_backlight = NULL;
420	mutex_unlock(&pmac_backlight_mutex);
421#endif
422
423	blocking_notifier_call_chain(&backlight_notifier,
424				     BACKLIGHT_UNREGISTERED, bd);
425
426	mutex_lock(&bd->ops_lock);
427	bd->ops = NULL;
428	mutex_unlock(&bd->ops_lock);
429
430	backlight_unregister_fb(bd);
431	device_unregister(&bd->dev);
432}
433EXPORT_SYMBOL(backlight_device_unregister);
434
435static void devm_backlight_device_release(struct device *dev, void *res)
436{
437	struct backlight_device *backlight = *(struct backlight_device **)res;
438
439	backlight_device_unregister(backlight);
440}
441
442static int devm_backlight_device_match(struct device *dev, void *res,
443					void *data)
444{
445	struct backlight_device **r = res;
446
447	return *r == data;
448}
449
450/**
451 * backlight_register_notifier - get notified of backlight (un)registration
452 * @nb: notifier block with the notifier to call on backlight (un)registration
453 *
454 * @return 0 on success, otherwise a negative error code
455 *
456 * Register a notifier to get notified when backlight devices get registered
457 * or unregistered.
458 */
459int backlight_register_notifier(struct notifier_block *nb)
460{
461	return blocking_notifier_chain_register(&backlight_notifier, nb);
462}
463EXPORT_SYMBOL(backlight_register_notifier);
464
465/**
466 * backlight_unregister_notifier - unregister a backlight notifier
467 * @nb: notifier block to unregister
468 *
469 * @return 0 on success, otherwise a negative error code
470 *
471 * Register a notifier to get notified when backlight devices get registered
472 * or unregistered.
473 */
474int backlight_unregister_notifier(struct notifier_block *nb)
475{
476	return blocking_notifier_chain_unregister(&backlight_notifier, nb);
477}
478EXPORT_SYMBOL(backlight_unregister_notifier);
479
480/**
481 * devm_backlight_device_register - resource managed backlight_device_register()
482 * @dev: the device to register
483 * @name: the name of the device
484 * @parent: a pointer to the parent device
485 * @devdata: an optional pointer to be stored for private driver use
486 * @ops: the backlight operations structure
487 * @props: the backlight properties
488 *
489 * @return a struct backlight on success, or an ERR_PTR on error
490 *
491 * Managed backlight_device_register(). The backlight_device returned
492 * from this function are automatically freed on driver detach.
493 * See backlight_device_register() for more information.
494 */
495struct backlight_device *devm_backlight_device_register(struct device *dev,
496	const char *name, struct device *parent, void *devdata,
497	const struct backlight_ops *ops,
498	const struct backlight_properties *props)
499{
500	struct backlight_device **ptr, *backlight;
501
502	ptr = devres_alloc(devm_backlight_device_release, sizeof(*ptr),
503			GFP_KERNEL);
504	if (!ptr)
505		return ERR_PTR(-ENOMEM);
506
507	backlight = backlight_device_register(name, parent, devdata, ops,
508						props);
509	if (!IS_ERR(backlight)) {
510		*ptr = backlight;
511		devres_add(dev, ptr);
512	} else {
513		devres_free(ptr);
514	}
515
516	return backlight;
517}
518EXPORT_SYMBOL(devm_backlight_device_register);
519
520/**
521 * devm_backlight_device_unregister - resource managed backlight_device_unregister()
522 * @dev: the device to unregister
523 * @bd: the backlight device to unregister
524 *
525 * Deallocated a backlight allocated with devm_backlight_device_register().
526 * Normally this function will not need to be called and the resource management
527 * code will ensure that the resource is freed.
528 */
529void devm_backlight_device_unregister(struct device *dev,
530				struct backlight_device *bd)
531{
532	int rc;
533
534	rc = devres_release(dev, devm_backlight_device_release,
535				devm_backlight_device_match, bd);
536	WARN_ON(rc);
537}
538EXPORT_SYMBOL(devm_backlight_device_unregister);
539
540#ifdef CONFIG_OF
541static int of_parent_match(struct device *dev, const void *data)
542{
543	return dev->parent && dev->parent->of_node == data;
544}
545
546/**
547 * of_find_backlight_by_node() - find backlight device by device-tree node
548 * @node: device-tree node of the backlight device
549 *
550 * Returns a pointer to the backlight device corresponding to the given DT
551 * node or NULL if no such backlight device exists or if the device hasn't
552 * been probed yet.
553 *
554 * This function obtains a reference on the backlight device and it is the
555 * caller's responsibility to drop the reference by calling put_device() on
556 * the backlight device's .dev field.
557 */
558struct backlight_device *of_find_backlight_by_node(struct device_node *node)
559{
560	struct device *dev;
561
562	dev = class_find_device(backlight_class, NULL, node, of_parent_match);
563
564	return dev ? to_backlight_device(dev) : NULL;
565}
566EXPORT_SYMBOL(of_find_backlight_by_node);
567#endif
568
569static void __exit backlight_class_exit(void)
570{
571	class_destroy(backlight_class);
572}
573
574static int __init backlight_class_init(void)
575{
576	backlight_class = class_create(THIS_MODULE, "backlight");
577	if (IS_ERR(backlight_class)) {
578		pr_warn("Unable to create backlight class; errno = %ld\n",
579			PTR_ERR(backlight_class));
580		return PTR_ERR(backlight_class);
581	}
582
583	backlight_class->dev_groups = bl_device_groups;
584	backlight_class->pm = &backlight_class_dev_pm_ops;
585	INIT_LIST_HEAD(&backlight_dev_list);
586	mutex_init(&backlight_dev_list_mutex);
587	BLOCKING_INIT_NOTIFIER_HEAD(&backlight_notifier);
588
589	return 0;
590}
591
592/*
593 * if this is compiled into the kernel, we need to ensure that the
594 * class is registered before users of the class try to register lcd's
595 */
596postcore_initcall(backlight_class_init);
597module_exit(backlight_class_exit);
598
599MODULE_LICENSE("GPL");
600MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
601MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");
602