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);
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 bd->props.power = power;
149 backlight_update_status(bd);
153 mutex_unlock(&bd->ops_lock);
157 static DEVICE_ATTR_RW(bl_power);
159 static ssize_t brightness_show(struct device *dev,
160 struct device_attribute *attr, char *buf)
162 struct backlight_device *bd = to_backlight_device(dev);
164 return sprintf(buf, "%d\n", bd->props.brightness);
167 static ssize_t brightness_store(struct device *dev,
168 struct device_attribute *attr, const char *buf, size_t count)
171 struct backlight_device *bd = to_backlight_device(dev);
172 unsigned long brightness;
174 rc = kstrtoul(buf, 0, &brightness);
180 mutex_lock(&bd->ops_lock);
182 if (brightness > bd->props.max_brightness)
185 pr_debug("set brightness to %lu\n", brightness);
186 bd->props.brightness = brightness;
187 backlight_update_status(bd);
191 mutex_unlock(&bd->ops_lock);
193 backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);
197 static DEVICE_ATTR_RW(brightness);
199 static ssize_t type_show(struct device *dev, struct device_attribute *attr,
202 struct backlight_device *bd = to_backlight_device(dev);
204 return sprintf(buf, "%s\n", backlight_types[bd->props.type]);
206 static DEVICE_ATTR_RO(type);
208 static ssize_t max_brightness_show(struct device *dev,
209 struct device_attribute *attr, char *buf)
211 struct backlight_device *bd = to_backlight_device(dev);
213 return sprintf(buf, "%d\n", bd->props.max_brightness);
215 static DEVICE_ATTR_RO(max_brightness);
217 static ssize_t actual_brightness_show(struct device *dev,
218 struct device_attribute *attr, char *buf)
221 struct backlight_device *bd = to_backlight_device(dev);
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 mutex_unlock(&bd->ops_lock);
230 static DEVICE_ATTR_RO(actual_brightness);
232 static struct class *backlight_class;
234 #ifdef CONFIG_PM_SLEEP
235 static int backlight_suspend(struct device *dev)
237 struct backlight_device *bd = to_backlight_device(dev);
239 mutex_lock(&bd->ops_lock);
240 if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
241 bd->props.state |= BL_CORE_SUSPENDED;
242 backlight_update_status(bd);
244 mutex_unlock(&bd->ops_lock);
249 static int backlight_resume(struct device *dev)
251 struct backlight_device *bd = to_backlight_device(dev);
253 mutex_lock(&bd->ops_lock);
254 if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
255 bd->props.state &= ~BL_CORE_SUSPENDED;
256 backlight_update_status(bd);
258 mutex_unlock(&bd->ops_lock);
264 static SIMPLE_DEV_PM_OPS(backlight_class_dev_pm_ops, backlight_suspend,
267 static void bl_device_release(struct device *dev)
269 struct backlight_device *bd = to_backlight_device(dev);
273 static struct attribute *bl_device_attrs[] = {
274 &dev_attr_bl_power.attr,
275 &dev_attr_brightness.attr,
276 &dev_attr_actual_brightness.attr,
277 &dev_attr_max_brightness.attr,
281 ATTRIBUTE_GROUPS(bl_device);
284 * backlight_force_update - tell the backlight subsystem that hardware state
286 * @bd: the backlight device to update
288 * Updates the internal state of the backlight in response to a hardware event,
289 * and generate a uevent to notify userspace
291 void backlight_force_update(struct backlight_device *bd,
292 enum backlight_update_reason reason)
294 mutex_lock(&bd->ops_lock);
295 if (bd->ops && bd->ops->get_brightness)
296 bd->props.brightness = bd->ops->get_brightness(bd);
297 mutex_unlock(&bd->ops_lock);
298 backlight_generate_event(bd, reason);
300 EXPORT_SYMBOL(backlight_force_update);
303 * backlight_device_register - create and register a new object of
304 * backlight_device class.
305 * @name: the name of the new object(must be the same as the name of the
306 * respective framebuffer device).
307 * @parent: a pointer to the parent device
308 * @devdata: an optional pointer to be stored for private driver use. The
309 * methods may retrieve it by using bl_get_data(bd).
310 * @ops: the backlight operations structure.
312 * Creates and registers new backlight device. Returns either an
313 * ERR_PTR() or a pointer to the newly allocated device.
315 struct backlight_device *backlight_device_register(const char *name,
316 struct device *parent, void *devdata, const struct backlight_ops *ops,
317 const struct backlight_properties *props)
319 struct backlight_device *new_bd;
322 pr_debug("backlight_device_register: name=%s\n", name);
324 new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
326 return ERR_PTR(-ENOMEM);
328 mutex_init(&new_bd->update_lock);
329 mutex_init(&new_bd->ops_lock);
331 new_bd->dev.class = backlight_class;
332 new_bd->dev.parent = parent;
333 new_bd->dev.release = bl_device_release;
334 dev_set_name(&new_bd->dev, "%s", name);
335 dev_set_drvdata(&new_bd->dev, devdata);
337 /* Set default properties */
339 memcpy(&new_bd->props, props,
340 sizeof(struct backlight_properties));
341 if (props->type <= 0 || props->type >= BACKLIGHT_TYPE_MAX) {
342 WARN(1, "%s: invalid backlight type", name);
343 new_bd->props.type = BACKLIGHT_RAW;
346 new_bd->props.type = BACKLIGHT_RAW;
349 rc = device_register(&new_bd->dev);
351 put_device(&new_bd->dev);
355 rc = backlight_register_fb(new_bd);
357 device_unregister(&new_bd->dev);
363 #ifdef CONFIG_PMAC_BACKLIGHT
364 mutex_lock(&pmac_backlight_mutex);
366 pmac_backlight = new_bd;
367 mutex_unlock(&pmac_backlight_mutex);
370 mutex_lock(&backlight_dev_list_mutex);
371 list_add(&new_bd->entry, &backlight_dev_list);
372 mutex_unlock(&backlight_dev_list_mutex);
374 blocking_notifier_call_chain(&backlight_notifier,
375 BACKLIGHT_REGISTERED, new_bd);
379 EXPORT_SYMBOL(backlight_device_register);
381 bool backlight_device_registered(enum backlight_type type)
384 struct backlight_device *bd;
386 mutex_lock(&backlight_dev_list_mutex);
387 list_for_each_entry(bd, &backlight_dev_list, entry) {
388 if (bd->props.type == type) {
393 mutex_unlock(&backlight_dev_list_mutex);
397 EXPORT_SYMBOL(backlight_device_registered);
400 * backlight_device_unregister - unregisters a backlight device object.
401 * @bd: the backlight device object to be unregistered and freed.
403 * Unregisters a previously registered via backlight_device_register object.
405 void backlight_device_unregister(struct backlight_device *bd)
410 mutex_lock(&backlight_dev_list_mutex);
411 list_del(&bd->entry);
412 mutex_unlock(&backlight_dev_list_mutex);
414 #ifdef CONFIG_PMAC_BACKLIGHT
415 mutex_lock(&pmac_backlight_mutex);
416 if (pmac_backlight == bd)
417 pmac_backlight = NULL;
418 mutex_unlock(&pmac_backlight_mutex);
421 blocking_notifier_call_chain(&backlight_notifier,
422 BACKLIGHT_UNREGISTERED, bd);
424 mutex_lock(&bd->ops_lock);
426 mutex_unlock(&bd->ops_lock);
428 backlight_unregister_fb(bd);
429 device_unregister(&bd->dev);
431 EXPORT_SYMBOL(backlight_device_unregister);
433 static void devm_backlight_device_release(struct device *dev, void *res)
435 struct backlight_device *backlight = *(struct backlight_device **)res;
437 backlight_device_unregister(backlight);
440 static int devm_backlight_device_match(struct device *dev, void *res,
443 struct backlight_device **r = res;
449 * backlight_register_notifier - get notified of backlight (un)registration
450 * @nb: notifier block with the notifier to call on backlight (un)registration
452 * @return 0 on success, otherwise a negative error code
454 * Register a notifier to get notified when backlight devices get registered
457 int backlight_register_notifier(struct notifier_block *nb)
459 return blocking_notifier_chain_register(&backlight_notifier, nb);
461 EXPORT_SYMBOL(backlight_register_notifier);
464 * backlight_unregister_notifier - unregister a backlight notifier
465 * @nb: notifier block to unregister
467 * @return 0 on success, otherwise a negative error code
469 * Register a notifier to get notified when backlight devices get registered
472 int backlight_unregister_notifier(struct notifier_block *nb)
474 return blocking_notifier_chain_unregister(&backlight_notifier, nb);
476 EXPORT_SYMBOL(backlight_unregister_notifier);
479 * devm_backlight_device_register - resource managed backlight_device_register()
480 * @dev: the device to register
481 * @name: the name of the device
482 * @parent: a pointer to the parent device
483 * @devdata: an optional pointer to be stored for private driver use
484 * @ops: the backlight operations structure
485 * @props: the backlight properties
487 * @return a struct backlight on success, or an ERR_PTR on error
489 * Managed backlight_device_register(). The backlight_device returned
490 * from this function are automatically freed on driver detach.
491 * See backlight_device_register() for more information.
493 struct backlight_device *devm_backlight_device_register(struct device *dev,
494 const char *name, struct device *parent, void *devdata,
495 const struct backlight_ops *ops,
496 const struct backlight_properties *props)
498 struct backlight_device **ptr, *backlight;
500 ptr = devres_alloc(devm_backlight_device_release, sizeof(*ptr),
503 return ERR_PTR(-ENOMEM);
505 backlight = backlight_device_register(name, parent, devdata, ops,
507 if (!IS_ERR(backlight)) {
509 devres_add(dev, ptr);
516 EXPORT_SYMBOL(devm_backlight_device_register);
519 * devm_backlight_device_unregister - resource managed backlight_device_unregister()
520 * @dev: the device to unregister
521 * @bd: the backlight device to unregister
523 * Deallocated a backlight allocated with devm_backlight_device_register().
524 * Normally this function will not need to be called and the resource management
525 * code will ensure that the resource is freed.
527 void devm_backlight_device_unregister(struct device *dev,
528 struct backlight_device *bd)
532 rc = devres_release(dev, devm_backlight_device_release,
533 devm_backlight_device_match, bd);
536 EXPORT_SYMBOL(devm_backlight_device_unregister);
539 static int of_parent_match(struct device *dev, const void *data)
541 return dev->parent && dev->parent->of_node == data;
545 * of_find_backlight_by_node() - find backlight device by device-tree node
546 * @node: device-tree node of the backlight device
548 * Returns a pointer to the backlight device corresponding to the given DT
549 * node or NULL if no such backlight device exists or if the device hasn't
552 * This function obtains a reference on the backlight device and it is the
553 * caller's responsibility to drop the reference by calling put_device() on
554 * the backlight device's .dev field.
556 struct backlight_device *of_find_backlight_by_node(struct device_node *node)
560 dev = class_find_device(backlight_class, NULL, node, of_parent_match);
562 return dev ? to_backlight_device(dev) : NULL;
564 EXPORT_SYMBOL(of_find_backlight_by_node);
567 static void __exit backlight_class_exit(void)
569 class_destroy(backlight_class);
572 static int __init backlight_class_init(void)
574 backlight_class = class_create(THIS_MODULE, "backlight");
575 if (IS_ERR(backlight_class)) {
576 pr_warn("Unable to create backlight class; errno = %ld\n",
577 PTR_ERR(backlight_class));
578 return PTR_ERR(backlight_class);
581 backlight_class->dev_groups = bl_device_groups;
582 backlight_class->pm = &backlight_class_dev_pm_ops;
583 INIT_LIST_HEAD(&backlight_dev_list);
584 mutex_init(&backlight_dev_list_mutex);
585 BLOCKING_INIT_NOTIFIER_HEAD(&backlight_notifier);
591 * if this is compiled into the kernel, we need to ensure that the
592 * class is registered before users of the class try to register lcd's
594 postcore_initcall(backlight_class_init);
595 module_exit(backlight_class_exit);
597 MODULE_LICENSE("GPL");
598 MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
599 MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");