2 * Backlight Lowlevel Control Abstraction
4 * Copyright (C) 2003,2004 Hewlett-Packard Company
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
18 #include <linux/slab.h>
20 #ifdef CONFIG_PMAC_BACKLIGHT
21 #include <asm/backlight.h>
24 static struct list_head backlight_dev_list;
25 static struct mutex backlight_dev_list_mutex;
26 static struct blocking_notifier_head backlight_notifier;
28 static const char *const backlight_types[] = {
29 [BACKLIGHT_RAW] = "raw",
30 [BACKLIGHT_PLATFORM] = "platform",
31 [BACKLIGHT_FIRMWARE] = "firmware",
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 ...
40 static int fb_notifier_callback(struct notifier_block *self,
41 unsigned long event, void *data)
43 struct backlight_device *bd;
44 struct fb_event *evdata = data;
45 int node = evdata->info->node;
48 /* If we aren't interested in this event, skip it immediately ... */
49 if (event != FB_EVENT_BLANK && event != FB_EVENT_CONBLANK)
52 bd = container_of(self, struct backlight_device, fb_notif);
53 mutex_lock(&bd->ops_lock);
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);
66 } else if (fb_blank != FB_BLANK_UNBLANK &&
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);
76 mutex_unlock(&bd->ops_lock);
80 static int backlight_register_fb(struct backlight_device *bd)
82 memset(&bd->fb_notif, 0, sizeof(bd->fb_notif));
83 bd->fb_notif.notifier_call = fb_notifier_callback;
85 return fb_register_client(&bd->fb_notif);
88 static void backlight_unregister_fb(struct backlight_device *bd)
90 fb_unregister_client(&bd->fb_notif);
93 static inline int backlight_register_fb(struct backlight_device *bd)
98 static inline void backlight_unregister_fb(struct backlight_device *bd)
101 #endif /* CONFIG_FB */
103 static void backlight_generate_event(struct backlight_device *bd,
104 enum backlight_update_reason reason)
109 case BACKLIGHT_UPDATE_SYSFS:
110 envp[0] = "SOURCE=sysfs";
112 case BACKLIGHT_UPDATE_HOTKEY:
113 envp[0] = "SOURCE=hotkey";
116 envp[0] = "SOURCE=unknown";
120 kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp);
121 sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
124 static ssize_t bl_power_show(struct device *dev, struct device_attribute *attr,
127 struct backlight_device *bd = to_backlight_device(dev);
129 return sprintf(buf, "%d\n", bd->props.power);
132 static ssize_t bl_power_store(struct device *dev, struct device_attribute *attr,
133 const char *buf, size_t count)
136 struct backlight_device *bd = to_backlight_device(dev);
137 unsigned long power, old_power;
139 rc = kstrtoul(buf, 0, &power);
144 mutex_lock(&bd->ops_lock);
146 pr_debug("set power to %lu\n", power);
147 if (bd->props.power != power) {
148 old_power = bd->props.power;
149 bd->props.power = power;
150 rc = backlight_update_status(bd);
152 bd->props.power = old_power;
159 mutex_unlock(&bd->ops_lock);
163 static DEVICE_ATTR_RW(bl_power);
165 static ssize_t brightness_show(struct device *dev,
166 struct device_attribute *attr, char *buf)
168 struct backlight_device *bd = to_backlight_device(dev);
170 return sprintf(buf, "%d\n", bd->props.brightness);
173 int backlight_device_set_brightness(struct backlight_device *bd,
174 unsigned long brightness)
178 mutex_lock(&bd->ops_lock);
180 if (brightness > bd->props.max_brightness)
183 pr_debug("set brightness to %lu\n", brightness);
184 bd->props.brightness = brightness;
185 rc = backlight_update_status(bd);
188 mutex_unlock(&bd->ops_lock);
190 backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);
194 EXPORT_SYMBOL(backlight_device_set_brightness);
196 static ssize_t brightness_store(struct device *dev,
197 struct device_attribute *attr, const char *buf, size_t count)
200 struct backlight_device *bd = to_backlight_device(dev);
201 unsigned long brightness;
203 rc = kstrtoul(buf, 0, &brightness);
207 rc = backlight_device_set_brightness(bd, brightness);
209 return rc ? rc : count;
211 static DEVICE_ATTR_RW(brightness);
213 static ssize_t type_show(struct device *dev, struct device_attribute *attr,
216 struct backlight_device *bd = to_backlight_device(dev);
218 return sprintf(buf, "%s\n", backlight_types[bd->props.type]);
220 static DEVICE_ATTR_RO(type);
222 static ssize_t max_brightness_show(struct device *dev,
223 struct device_attribute *attr, char *buf)
225 struct backlight_device *bd = to_backlight_device(dev);
227 return sprintf(buf, "%d\n", bd->props.max_brightness);
229 static DEVICE_ATTR_RO(max_brightness);
231 static ssize_t actual_brightness_show(struct device *dev,
232 struct device_attribute *attr, char *buf)
235 struct backlight_device *bd = to_backlight_device(dev);
237 mutex_lock(&bd->ops_lock);
238 if (bd->ops && bd->ops->get_brightness)
239 rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
241 rc = sprintf(buf, "%d\n", bd->props.brightness);
242 mutex_unlock(&bd->ops_lock);
246 static DEVICE_ATTR_RO(actual_brightness);
248 static struct class *backlight_class;
250 #ifdef CONFIG_PM_SLEEP
251 static int backlight_suspend(struct device *dev)
253 struct backlight_device *bd = to_backlight_device(dev);
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);
260 mutex_unlock(&bd->ops_lock);
265 static int backlight_resume(struct device *dev)
267 struct backlight_device *bd = to_backlight_device(dev);
269 mutex_lock(&bd->ops_lock);
270 if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
271 bd->props.state &= ~BL_CORE_SUSPENDED;
272 backlight_update_status(bd);
274 mutex_unlock(&bd->ops_lock);
280 static SIMPLE_DEV_PM_OPS(backlight_class_dev_pm_ops, backlight_suspend,
283 static void bl_device_release(struct device *dev)
285 struct backlight_device *bd = to_backlight_device(dev);
289 static struct attribute *bl_device_attrs[] = {
290 &dev_attr_bl_power.attr,
291 &dev_attr_brightness.attr,
292 &dev_attr_actual_brightness.attr,
293 &dev_attr_max_brightness.attr,
297 ATTRIBUTE_GROUPS(bl_device);
300 * backlight_force_update - tell the backlight subsystem that hardware state
302 * @bd: the backlight device to update
304 * Updates the internal state of the backlight in response to a hardware event,
305 * and generate a uevent to notify userspace
307 void backlight_force_update(struct backlight_device *bd,
308 enum backlight_update_reason reason)
310 mutex_lock(&bd->ops_lock);
311 if (bd->ops && bd->ops->get_brightness)
312 bd->props.brightness = bd->ops->get_brightness(bd);
313 mutex_unlock(&bd->ops_lock);
314 backlight_generate_event(bd, reason);
316 EXPORT_SYMBOL(backlight_force_update);
319 * backlight_device_register - create and register a new object of
320 * backlight_device class.
321 * @name: the name of the new object(must be the same as the name of the
322 * respective framebuffer device).
323 * @parent: a pointer to the parent device
324 * @devdata: an optional pointer to be stored for private driver use. The
325 * methods may retrieve it by using bl_get_data(bd).
326 * @ops: the backlight operations structure.
328 * Creates and registers new backlight device. Returns either an
329 * ERR_PTR() or a pointer to the newly allocated device.
331 struct backlight_device *backlight_device_register(const char *name,
332 struct device *parent, void *devdata, const struct backlight_ops *ops,
333 const struct backlight_properties *props)
335 struct backlight_device *new_bd;
338 pr_debug("backlight_device_register: name=%s\n", name);
340 new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
342 return ERR_PTR(-ENOMEM);
344 mutex_init(&new_bd->update_lock);
345 mutex_init(&new_bd->ops_lock);
347 new_bd->dev.class = backlight_class;
348 new_bd->dev.parent = parent;
349 new_bd->dev.release = bl_device_release;
350 dev_set_name(&new_bd->dev, "%s", name);
351 dev_set_drvdata(&new_bd->dev, devdata);
353 /* Set default properties */
355 memcpy(&new_bd->props, props,
356 sizeof(struct backlight_properties));
357 if (props->type <= 0 || props->type >= BACKLIGHT_TYPE_MAX) {
358 WARN(1, "%s: invalid backlight type", name);
359 new_bd->props.type = BACKLIGHT_RAW;
362 new_bd->props.type = BACKLIGHT_RAW;
365 rc = device_register(&new_bd->dev);
367 put_device(&new_bd->dev);
371 rc = backlight_register_fb(new_bd);
373 device_unregister(&new_bd->dev);
379 #ifdef CONFIG_PMAC_BACKLIGHT
380 mutex_lock(&pmac_backlight_mutex);
382 pmac_backlight = new_bd;
383 mutex_unlock(&pmac_backlight_mutex);
386 mutex_lock(&backlight_dev_list_mutex);
387 list_add(&new_bd->entry, &backlight_dev_list);
388 mutex_unlock(&backlight_dev_list_mutex);
390 blocking_notifier_call_chain(&backlight_notifier,
391 BACKLIGHT_REGISTERED, new_bd);
395 EXPORT_SYMBOL(backlight_device_register);
397 struct backlight_device *backlight_device_get_by_type(enum backlight_type type)
400 struct backlight_device *bd;
402 mutex_lock(&backlight_dev_list_mutex);
403 list_for_each_entry(bd, &backlight_dev_list, entry) {
404 if (bd->props.type == type) {
409 mutex_unlock(&backlight_dev_list_mutex);
411 return found ? bd : NULL;
413 EXPORT_SYMBOL(backlight_device_get_by_type);
416 * backlight_device_unregister - unregisters a backlight device object.
417 * @bd: the backlight device object to be unregistered and freed.
419 * Unregisters a previously registered via backlight_device_register object.
421 void backlight_device_unregister(struct backlight_device *bd)
426 mutex_lock(&backlight_dev_list_mutex);
427 list_del(&bd->entry);
428 mutex_unlock(&backlight_dev_list_mutex);
430 #ifdef CONFIG_PMAC_BACKLIGHT
431 mutex_lock(&pmac_backlight_mutex);
432 if (pmac_backlight == bd)
433 pmac_backlight = NULL;
434 mutex_unlock(&pmac_backlight_mutex);
437 blocking_notifier_call_chain(&backlight_notifier,
438 BACKLIGHT_UNREGISTERED, bd);
440 mutex_lock(&bd->ops_lock);
442 mutex_unlock(&bd->ops_lock);
444 backlight_unregister_fb(bd);
445 device_unregister(&bd->dev);
447 EXPORT_SYMBOL(backlight_device_unregister);
449 static void devm_backlight_device_release(struct device *dev, void *res)
451 struct backlight_device *backlight = *(struct backlight_device **)res;
453 backlight_device_unregister(backlight);
456 static int devm_backlight_device_match(struct device *dev, void *res,
459 struct backlight_device **r = res;
465 * backlight_register_notifier - get notified of backlight (un)registration
466 * @nb: notifier block with the notifier to call on backlight (un)registration
468 * @return 0 on success, otherwise a negative error code
470 * Register a notifier to get notified when backlight devices get registered
473 int backlight_register_notifier(struct notifier_block *nb)
475 return blocking_notifier_chain_register(&backlight_notifier, nb);
477 EXPORT_SYMBOL(backlight_register_notifier);
480 * backlight_unregister_notifier - unregister a backlight notifier
481 * @nb: notifier block to unregister
483 * @return 0 on success, otherwise a negative error code
485 * Register a notifier to get notified when backlight devices get registered
488 int backlight_unregister_notifier(struct notifier_block *nb)
490 return blocking_notifier_chain_unregister(&backlight_notifier, nb);
492 EXPORT_SYMBOL(backlight_unregister_notifier);
495 * devm_backlight_device_register - resource managed backlight_device_register()
496 * @dev: the device to register
497 * @name: the name of the device
498 * @parent: a pointer to the parent device
499 * @devdata: an optional pointer to be stored for private driver use
500 * @ops: the backlight operations structure
501 * @props: the backlight properties
503 * @return a struct backlight on success, or an ERR_PTR on error
505 * Managed backlight_device_register(). The backlight_device returned
506 * from this function are automatically freed on driver detach.
507 * See backlight_device_register() for more information.
509 struct backlight_device *devm_backlight_device_register(struct device *dev,
510 const char *name, struct device *parent, void *devdata,
511 const struct backlight_ops *ops,
512 const struct backlight_properties *props)
514 struct backlight_device **ptr, *backlight;
516 ptr = devres_alloc(devm_backlight_device_release, sizeof(*ptr),
519 return ERR_PTR(-ENOMEM);
521 backlight = backlight_device_register(name, parent, devdata, ops,
523 if (!IS_ERR(backlight)) {
525 devres_add(dev, ptr);
532 EXPORT_SYMBOL(devm_backlight_device_register);
535 * devm_backlight_device_unregister - resource managed backlight_device_unregister()
536 * @dev: the device to unregister
537 * @bd: the backlight device to unregister
539 * Deallocated a backlight allocated with devm_backlight_device_register().
540 * Normally this function will not need to be called and the resource management
541 * code will ensure that the resource is freed.
543 void devm_backlight_device_unregister(struct device *dev,
544 struct backlight_device *bd)
548 rc = devres_release(dev, devm_backlight_device_release,
549 devm_backlight_device_match, bd);
552 EXPORT_SYMBOL(devm_backlight_device_unregister);
555 static int of_parent_match(struct device *dev, const void *data)
557 return dev->parent && dev->parent->of_node == data;
561 * of_find_backlight_by_node() - find backlight device by device-tree node
562 * @node: device-tree node of the backlight device
564 * Returns a pointer to the backlight device corresponding to the given DT
565 * node or NULL if no such backlight device exists or if the device hasn't
568 * This function obtains a reference on the backlight device and it is the
569 * caller's responsibility to drop the reference by calling put_device() on
570 * the backlight device's .dev field.
572 struct backlight_device *of_find_backlight_by_node(struct device_node *node)
576 dev = class_find_device(backlight_class, NULL, node, of_parent_match);
578 return dev ? to_backlight_device(dev) : NULL;
580 EXPORT_SYMBOL(of_find_backlight_by_node);
584 * of_find_backlight - Get backlight device
587 * This function looks for a property named 'backlight' on the DT node
588 * connected to @dev and looks up the backlight device.
590 * Call backlight_put() to drop the reference on the backlight device.
593 * A pointer to the backlight device if found.
594 * Error pointer -EPROBE_DEFER if the DT property is set, but no backlight
596 * NULL if there's no backlight property.
598 struct backlight_device *of_find_backlight(struct device *dev)
600 struct backlight_device *bd = NULL;
601 struct device_node *np;
606 if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
607 np = of_parse_phandle(dev->of_node, "backlight", 0);
609 bd = of_find_backlight_by_node(np);
612 return ERR_PTR(-EPROBE_DEFER);
614 * Note: gpio_backlight uses brightness as
615 * power state during probe
617 if (!bd->props.brightness)
618 bd->props.brightness = bd->props.max_brightness;
624 EXPORT_SYMBOL(of_find_backlight);
626 static void devm_backlight_release(void *data)
632 * devm_of_find_backlight - Resource-managed of_find_backlight()
635 * Device managed version of of_find_backlight().
636 * The reference on the backlight device is automatically
637 * dropped on driver detach.
639 struct backlight_device *devm_of_find_backlight(struct device *dev)
641 struct backlight_device *bd;
644 bd = of_find_backlight(dev);
645 if (IS_ERR_OR_NULL(bd))
647 ret = devm_add_action(dev, devm_backlight_release, bd);
654 EXPORT_SYMBOL(devm_of_find_backlight);
656 static void __exit backlight_class_exit(void)
658 class_destroy(backlight_class);
661 static int __init backlight_class_init(void)
663 backlight_class = class_create(THIS_MODULE, "backlight");
664 if (IS_ERR(backlight_class)) {
665 pr_warn("Unable to create backlight class; errno = %ld\n",
666 PTR_ERR(backlight_class));
667 return PTR_ERR(backlight_class);
670 backlight_class->dev_groups = bl_device_groups;
671 backlight_class->pm = &backlight_class_dev_pm_ops;
672 INIT_LIST_HEAD(&backlight_dev_list);
673 mutex_init(&backlight_dev_list_mutex);
674 BLOCKING_INIT_NOTIFIER_HEAD(&backlight_notifier);
680 * if this is compiled into the kernel, we need to ensure that the
681 * class is registered before users of the class try to register lcd's
683 postcore_initcall(backlight_class_init);
684 module_exit(backlight_class_exit);
686 MODULE_LICENSE("GPL");
687 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
688 MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");