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