drivers/acpi/button.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  button.c - ACPI Button Driver
   4  *
   5  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
   6  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
   7  */
   8
   9 #define pr_fmt(fmt) "ACPI: button: " fmt
  10
  11 #include <linux/compiler.h>
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <linux/types.h>
  16 #include <linux/proc_fs.h>
  17 #include <linux/seq_file.h>
  18 #include <linux/input.h>
  19 #include <linux/slab.h>
  20 #include <linux/acpi.h>
  21 #include <linux/dmi.h>
  22 #include <acpi/button.h>
  23
  24 #define ACPI_BUTTON_CLASS               "button"
  25 #define ACPI_BUTTON_FILE_STATE          "state"
  26 #define ACPI_BUTTON_TYPE_UNKNOWN        0x00
  27 #define ACPI_BUTTON_NOTIFY_STATUS       0x80
  28
  29 #define ACPI_BUTTON_SUBCLASS_POWER      "power"
  30 #define ACPI_BUTTON_DEVICE_NAME_POWER   "Power Button"
  31 #define ACPI_BUTTON_TYPE_POWER          0x01
  32
  33 #define ACPI_BUTTON_SUBCLASS_SLEEP      "sleep"
  34 #define ACPI_BUTTON_DEVICE_NAME_SLEEP   "Sleep Button"
  35 #define ACPI_BUTTON_TYPE_SLEEP          0x03
  36
  37 #define ACPI_BUTTON_SUBCLASS_LID        "lid"
  38 #define ACPI_BUTTON_DEVICE_NAME_LID     "Lid Switch"
  39 #define ACPI_BUTTON_TYPE_LID            0x05
  40
  41 enum {
  42         ACPI_BUTTON_LID_INIT_IGNORE,
  43         ACPI_BUTTON_LID_INIT_OPEN,
  44         ACPI_BUTTON_LID_INIT_METHOD,
  45         ACPI_BUTTON_LID_INIT_DISABLED,
  46 };
  47
  48 static const char * const lid_init_state_str[] = {
  49         [ACPI_BUTTON_LID_INIT_IGNORE]           = "ignore",
  50         [ACPI_BUTTON_LID_INIT_OPEN]             = "open",
  51         [ACPI_BUTTON_LID_INIT_METHOD]           = "method",
  52         [ACPI_BUTTON_LID_INIT_DISABLED]         = "disabled",
  53 };
  54
  55 MODULE_AUTHOR("Paul Diefenbaugh");
  56 MODULE_DESCRIPTION("ACPI Button Driver");
  57 MODULE_LICENSE("GPL");
  58
  59 static const struct acpi_device_id button_device_ids[] = {
  60         {ACPI_BUTTON_HID_LID,    0},
  61         {ACPI_BUTTON_HID_SLEEP,  0},
  62         {ACPI_BUTTON_HID_SLEEPF, 0},
  63         {ACPI_BUTTON_HID_POWER,  0},
  64         {ACPI_BUTTON_HID_POWERF, 0},
  65         {"", 0},
  66 };
  67 MODULE_DEVICE_TABLE(acpi, button_device_ids);
  68
  69 /* Please keep this list sorted alphabetically by vendor and model */
  70 static const struct dmi_system_id dmi_lid_quirks[] = {
  71         {
  72                 /* GP-electronic T701, _LID method points to a floating GPIO */
  73                 .matches = {
  74                         DMI_MATCH(DMI_SYS_VENDOR, "Insyde"),
  75                         DMI_MATCH(DMI_PRODUCT_NAME, "T701"),
  76                         DMI_MATCH(DMI_BIOS_VERSION, "BYT70A.YNCHENG.WIN.007"),
  77                 },
  78                 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_DISABLED,
  79         },
  80         {
  81                 /*
  82                  * Lenovo Yoga 9 14ITL5, initial notification of the LID device
  83                  * never happens.
  84                  */
  85                 .matches = {
  86                         DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
  87                         DMI_MATCH(DMI_PRODUCT_NAME, "82BG"),
  88                 },
  89                 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
  90         },
  91         {
  92                 /*
  93                  * Medion Akoya E2215T, notification of the LID device only
  94                  * happens on close, not on open and _LID always returns closed.
  95                  */
  96                 .matches = {
  97                         DMI_MATCH(DMI_SYS_VENDOR, "MEDION"),
  98                         DMI_MATCH(DMI_PRODUCT_NAME, "E2215T"),
  99                 },
 100                 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
 101         },
 102         {
 103                 /*
 104                  * Medion Akoya E2228T, notification of the LID device only
 105                  * happens on close, not on open and _LID always returns closed.
 106                  */
 107                 .matches = {
 108                         DMI_MATCH(DMI_SYS_VENDOR, "MEDION"),
 109                         DMI_MATCH(DMI_PRODUCT_NAME, "E2228T"),
 110                 },
 111                 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
 112         },
 113         {
 114                 /*
 115                  * Razer Blade Stealth 13 late 2019, notification of the LID device
 116                  * only happens on close, not on open and _LID always returns closed.
 117                  */
 118                 .matches = {
 119                         DMI_MATCH(DMI_SYS_VENDOR, "Razer"),
 120                         DMI_MATCH(DMI_PRODUCT_NAME, "Razer Blade Stealth 13 Late 2019"),
 121                 },
 122                 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
 123         },
 124         {}
 125 };
 126
 127 static int acpi_button_add(struct acpi_device *device);
 128 static int acpi_button_remove(struct acpi_device *device);
 129 static void acpi_button_notify(struct acpi_device *device, u32 event);
 130
 131 #ifdef CONFIG_PM_SLEEP
 132 static int acpi_button_suspend(struct device *dev);
 133 static int acpi_button_resume(struct device *dev);
 134 #else
 135 #define acpi_button_suspend NULL
 136 #define acpi_button_resume NULL
 137 #endif
 138 static SIMPLE_DEV_PM_OPS(acpi_button_pm, acpi_button_suspend, acpi_button_resume);
 139
 140 static struct acpi_driver acpi_button_driver = {
 141         .name = "button",
 142         .class = ACPI_BUTTON_CLASS,
 143         .ids = button_device_ids,
 144         .ops = {
 145                 .add = acpi_button_add,
 146                 .remove = acpi_button_remove,
 147                 .notify = acpi_button_notify,
 148         },
 149         .drv.pm = &acpi_button_pm,
 150 };
 151
 152 struct acpi_button {
 153         unsigned int type;
 154         struct input_dev *input;
 155         char phys[32];                  /* for input device */
 156         unsigned long pushed;
 157         int last_state;
 158         ktime_t last_time;
 159         bool suspended;
 160         bool lid_state_initialized;
 161 };
 162
 163 static struct acpi_device *lid_device;
 164 static long lid_init_state = -1;
 165
 166 static unsigned long lid_report_interval __read_mostly = 500;
 167 module_param(lid_report_interval, ulong, 0644);
 168 MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");
 169
 170 /* FS Interface (/proc) */
 171 static struct proc_dir_entry *acpi_button_dir;
 172 static struct proc_dir_entry *acpi_lid_dir;
 173
 174 static int acpi_lid_evaluate_state(struct acpi_device *device)
 175 {
 176         unsigned long long lid_state;
 177         acpi_status status;
 178
 179         status = acpi_evaluate_integer(device->handle, "_LID", NULL, &lid_state);
 180         if (ACPI_FAILURE(status))
 181                 return -ENODEV;
 182
 183         return lid_state ? 1 : 0;
 184 }
 185
 186 static int acpi_lid_notify_state(struct acpi_device *device, int state)
 187 {
 188         struct acpi_button *button = acpi_driver_data(device);
 189         ktime_t next_report;
 190         bool do_update;
 191
 192         /*
 193          * In lid_init_state=ignore mode, if user opens/closes lid
 194          * frequently with "open" missing, and "last_time" is also updated
 195          * frequently, "close" cannot be delivered to the userspace.
 196          * So "last_time" is only updated after a timeout or an actual
 197          * switch.
 198          */
 199         if (lid_init_state != ACPI_BUTTON_LID_INIT_IGNORE ||
 200             button->last_state != !!state)
 201                 do_update = true;
 202         else
 203                 do_update = false;
 204
 205         next_report = ktime_add(button->last_time,
 206                                 ms_to_ktime(lid_report_interval));
 207         if (button->last_state == !!state &&
 208             ktime_after(ktime_get(), next_report)) {
 209                 /* Complain the buggy firmware */
 210                 pr_warn_once("The lid device is not compliant to SW_LID.\n");
 211
 212                 /*
 213                  * Send the unreliable complement switch event:
 214                  *
 215                  * On most platforms, the lid device is reliable. However
 216                  * there are exceptions:
 217                  * 1. Platforms returning initial lid state as "close" by
 218                  *    default after booting/resuming:
 219                  *     https://bugzilla.kernel.org/show_bug.cgi?id=89211
 220                  *     https://bugzilla.kernel.org/show_bug.cgi?id=106151
 221                  * 2. Platforms never reporting "open" events:
 222                  *     https://bugzilla.kernel.org/show_bug.cgi?id=106941
 223                  * On these buggy platforms, the usage model of the ACPI
 224                  * lid device actually is:
 225                  * 1. The initial returning value of _LID may not be
 226                  *    reliable.
 227                  * 2. The open event may not be reliable.
 228                  * 3. The close event is reliable.
 229                  *
 230                  * But SW_LID is typed as input switch event, the input
 231                  * layer checks if the event is redundant. Hence if the
 232                  * state is not switched, the userspace cannot see this
 233                  * platform triggered reliable event. By inserting a
 234                  * complement switch event, it then is guaranteed that the
 235                  * platform triggered reliable one can always be seen by
 236                  * the userspace.
 237                  */
 238                 if (lid_init_state == ACPI_BUTTON_LID_INIT_IGNORE) {
 239                         do_update = true;
 240                         /*
 241                          * Do generate complement switch event for "close"
 242                          * as "close" is reliable and wrong "open" won't
 243                          * trigger unexpected behaviors.
 244                          * Do not generate complement switch event for
 245                          * "open" as "open" is not reliable and wrong
 246                          * "close" will trigger unexpected behaviors.
 247                          */
 248                         if (!state) {
 249                                 input_report_switch(button->input,
 250                                                     SW_LID, state);
 251                                 input_sync(button->input);
 252                         }
 253                 }
 254         }
 255         /* Send the platform triggered reliable event */
 256         if (do_update) {
 257                 acpi_handle_debug(device->handle, "ACPI LID %s\n",
 258                                   state ? "open" : "closed");
 259                 input_report_switch(button->input, SW_LID, !state);
 260                 input_sync(button->input);
 261                 button->last_state = !!state;
 262                 button->last_time = ktime_get();
 263         }
 264
 265         return 0;
 266 }
 267
 268 static int __maybe_unused acpi_button_state_seq_show(struct seq_file *seq,
 269                                                      void *offset)
 270 {
 271         struct acpi_device *device = seq->private;
 272         int state;
 273
 274         state = acpi_lid_evaluate_state(device);
 275         seq_printf(seq, "state:      %s\n",
 276                    state < 0 ? "unsupported" : (state ? "open" : "closed"));
 277         return 0;
 278 }
 279
 280 static int acpi_button_add_fs(struct acpi_device *device)
 281 {
 282         struct acpi_button *button = acpi_driver_data(device);
 283         struct proc_dir_entry *entry = NULL;
 284         int ret = 0;
 285
 286         /* procfs I/F for ACPI lid device only */
 287         if (button->type != ACPI_BUTTON_TYPE_LID)
 288                 return 0;
 289
 290         if (acpi_button_dir || acpi_lid_dir) {
 291                 pr_info("More than one Lid device found!\n");
 292                 return -EEXIST;
 293         }
 294
 295         /* create /proc/acpi/button */
 296         acpi_button_dir = proc_mkdir(ACPI_BUTTON_CLASS, acpi_root_dir);
 297         if (!acpi_button_dir)
 298                 return -ENODEV;
 299
 300         /* create /proc/acpi/button/lid */
 301         acpi_lid_dir = proc_mkdir(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
 302         if (!acpi_lid_dir) {
 303                 ret = -ENODEV;
 304                 goto remove_button_dir;
 305         }
 306
 307         /* create /proc/acpi/button/lid/LID/ */
 308         acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device), acpi_lid_dir);
 309         if (!acpi_device_dir(device)) {
 310                 ret = -ENODEV;
 311                 goto remove_lid_dir;
 312         }
 313
 314         /* create /proc/acpi/button/lid/LID/state */
 315         entry = proc_create_single_data(ACPI_BUTTON_FILE_STATE, S_IRUGO,
 316                         acpi_device_dir(device), acpi_button_state_seq_show,
 317                         device);
 318         if (!entry) {
 319                 ret = -ENODEV;
 320                 goto remove_dev_dir;
 321         }
 322
 323 done:
 324         return ret;
 325
 326 remove_dev_dir:
 327         remove_proc_entry(acpi_device_bid(device),
 328                           acpi_lid_dir);
 329         acpi_device_dir(device) = NULL;
 330 remove_lid_dir:
 331         remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
 332         acpi_lid_dir = NULL;
 333 remove_button_dir:
 334         remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
 335         acpi_button_dir = NULL;
 336         goto done;
 337 }
 338
 339 static int acpi_button_remove_fs(struct acpi_device *device)
 340 {
 341         struct acpi_button *button = acpi_driver_data(device);
 342
 343         if (button->type != ACPI_BUTTON_TYPE_LID)
 344                 return 0;
 345
 346         remove_proc_entry(ACPI_BUTTON_FILE_STATE,
 347                           acpi_device_dir(device));
 348         remove_proc_entry(acpi_device_bid(device),
 349                           acpi_lid_dir);
 350         acpi_device_dir(device) = NULL;
 351         remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
 352         acpi_lid_dir = NULL;
 353         remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
 354         acpi_button_dir = NULL;
 355
 356         return 0;
 357 }
 358
 359 /* Driver Interface */
 360 int acpi_lid_open(void)
 361 {
 362         if (!lid_device)
 363                 return -ENODEV;
 364
 365         return acpi_lid_evaluate_state(lid_device);
 366 }
 367 EXPORT_SYMBOL(acpi_lid_open);
 368
 369 static int acpi_lid_update_state(struct acpi_device *device,
 370                                  bool signal_wakeup)
 371 {
 372         int state;
 373
 374         state = acpi_lid_evaluate_state(device);
 375         if (state < 0)
 376                 return state;
 377
 378         if (state && signal_wakeup)
 379                 acpi_pm_wakeup_event(&device->dev);
 380
 381         return acpi_lid_notify_state(device, state);
 382 }
 383
 384 static void acpi_lid_initialize_state(struct acpi_device *device)
 385 {
 386         struct acpi_button *button = acpi_driver_data(device);
 387
 388         switch (lid_init_state) {
 389         case ACPI_BUTTON_LID_INIT_OPEN:
 390                 (void)acpi_lid_notify_state(device, 1);
 391                 break;
 392         case ACPI_BUTTON_LID_INIT_METHOD:
 393                 (void)acpi_lid_update_state(device, false);
 394                 break;
 395         case ACPI_BUTTON_LID_INIT_IGNORE:
 396         default:
 397                 break;
 398         }
 399
 400         button->lid_state_initialized = true;
 401 }
 402
 403 static void acpi_button_notify(struct acpi_device *device, u32 event)
 404 {
 405         struct acpi_button *button = acpi_driver_data(device);
 406         struct input_dev *input;
 407
 408         switch (event) {
 409         case ACPI_FIXED_HARDWARE_EVENT:
 410                 event = ACPI_BUTTON_NOTIFY_STATUS;
 411                 fallthrough;
 412         case ACPI_BUTTON_NOTIFY_STATUS:
 413                 input = button->input;
 414                 if (button->type == ACPI_BUTTON_TYPE_LID) {
 415                         if (button->lid_state_initialized)
 416                                 acpi_lid_update_state(device, true);
 417                 } else {
 418                         int keycode;
 419
 420                         acpi_pm_wakeup_event(&device->dev);
 421                         if (button->suspended)
 422                                 break;
 423
 424                         keycode = test_bit(KEY_SLEEP, input->keybit) ?
 425                                                 KEY_SLEEP : KEY_POWER;
 426                         input_report_key(input, keycode, 1);
 427                         input_sync(input);
 428                         input_report_key(input, keycode, 0);
 429                         input_sync(input);
 430
 431                         acpi_bus_generate_netlink_event(
 432                                         device->pnp.device_class,
 433                                         dev_name(&device->dev),
 434                                         event, ++button->pushed);
 435                 }
 436                 break;
 437         default:
 438                 acpi_handle_debug(device->handle, "Unsupported event [0x%x]\n",
 439                                   event);
 440                 break;
 441         }
 442 }
 443
 444 #ifdef CONFIG_PM_SLEEP
 445 static int acpi_button_suspend(struct device *dev)
 446 {
 447         struct acpi_device *device = to_acpi_device(dev);
 448         struct acpi_button *button = acpi_driver_data(device);
 449
 450         button->suspended = true;
 451         return 0;
 452 }
 453
 454 static int acpi_button_resume(struct device *dev)
 455 {
 456         struct acpi_device *device = to_acpi_device(dev);
 457         struct acpi_button *button = acpi_driver_data(device);
 458
 459         button->suspended = false;
 460         if (button->type == ACPI_BUTTON_TYPE_LID) {
 461                 button->last_state = !!acpi_lid_evaluate_state(device);
 462                 button->last_time = ktime_get();
 463                 acpi_lid_initialize_state(device);
 464         }
 465         return 0;
 466 }
 467 #endif
 468
 469 static int acpi_lid_input_open(struct input_dev *input)
 470 {
 471         struct acpi_device *device = input_get_drvdata(input);
 472         struct acpi_button *button = acpi_driver_data(device);
 473
 474         button->last_state = !!acpi_lid_evaluate_state(device);
 475         button->last_time = ktime_get();
 476         acpi_lid_initialize_state(device);
 477
 478         return 0;
 479 }
 480
 481 static int acpi_button_add(struct acpi_device *device)
 482 {
 483         struct acpi_button *button;
 484         struct input_dev *input;
 485         const char *hid = acpi_device_hid(device);
 486         char *name, *class;
 487         int error;
 488
 489         if (!strcmp(hid, ACPI_BUTTON_HID_LID) &&
 490              lid_init_state == ACPI_BUTTON_LID_INIT_DISABLED)
 491                 return -ENODEV;
 492
 493         button = kzalloc(sizeof(struct acpi_button), GFP_KERNEL);
 494         if (!button)
 495                 return -ENOMEM;
 496
 497         device->driver_data = button;
 498
 499         button->input = input = input_allocate_device();
 500         if (!input) {
 501                 error = -ENOMEM;
 502                 goto err_free_button;
 503         }
 504
 505         name = acpi_device_name(device);
 506         class = acpi_device_class(device);
 507
 508         if (!strcmp(hid, ACPI_BUTTON_HID_POWER) ||
 509             !strcmp(hid, ACPI_BUTTON_HID_POWERF)) {
 510                 button->type = ACPI_BUTTON_TYPE_POWER;
 511                 strcpy(name, ACPI_BUTTON_DEVICE_NAME_POWER);
 512                 sprintf(class, "%s/%s",
 513                         ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_POWER);
 514         } else if (!strcmp(hid, ACPI_BUTTON_HID_SLEEP) ||
 515                    !strcmp(hid, ACPI_BUTTON_HID_SLEEPF)) {
 516                 button->type = ACPI_BUTTON_TYPE_SLEEP;
 517                 strcpy(name, ACPI_BUTTON_DEVICE_NAME_SLEEP);
 518                 sprintf(class, "%s/%s",
 519                         ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_SLEEP);
 520         } else if (!strcmp(hid, ACPI_BUTTON_HID_LID)) {
 521                 button->type = ACPI_BUTTON_TYPE_LID;
 522                 strcpy(name, ACPI_BUTTON_DEVICE_NAME_LID);
 523                 sprintf(class, "%s/%s",
 524                         ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_LID);
 525                 input->open = acpi_lid_input_open;
 526         } else {
 527                 pr_info("Unsupported hid [%s]\n", hid);
 528                 error = -ENODEV;
 529                 goto err_free_input;
 530         }
 531
 532         error = acpi_button_add_fs(device);
 533         if (error)
 534                 goto err_free_input;
 535
 536         snprintf(button->phys, sizeof(button->phys), "%s/button/input0", hid);
 537
 538         input->name = name;
 539         input->phys = button->phys;
 540         input->id.bustype = BUS_HOST;
 541         input->id.product = button->type;
 542         input->dev.parent = &device->dev;
 543
 544         switch (button->type) {
 545         case ACPI_BUTTON_TYPE_POWER:
 546                 input_set_capability(input, EV_KEY, KEY_POWER);
 547                 break;
 548
 549         case ACPI_BUTTON_TYPE_SLEEP:
 550                 input_set_capability(input, EV_KEY, KEY_SLEEP);
 551                 break;
 552
 553         case ACPI_BUTTON_TYPE_LID:
 554                 input_set_capability(input, EV_SW, SW_LID);
 555                 break;
 556         }
 557
 558         input_set_drvdata(input, device);
 559         error = input_register_device(input);
 560         if (error)
 561                 goto err_remove_fs;
 562         if (button->type == ACPI_BUTTON_TYPE_LID) {
 563                 /*
 564                  * This assumes there's only one lid device, or if there are
 565                  * more we only care about the last one...
 566                  */
 567                 lid_device = device;
 568         }
 569
 570         device_init_wakeup(&device->dev, true);
 571         pr_info("%s [%s]\n", name, acpi_device_bid(device));
 572         return 0;
 573
 574  err_remove_fs:
 575         acpi_button_remove_fs(device);
 576  err_free_input:
 577         input_free_device(input);
 578  err_free_button:
 579         kfree(button);
 580         return error;
 581 }
 582
 583 static int acpi_button_remove(struct acpi_device *device)
 584 {
 585         struct acpi_button *button = acpi_driver_data(device);
 586
 587         acpi_button_remove_fs(device);
 588         input_unregister_device(button->input);
 589         kfree(button);
 590         return 0;
 591 }
 592
 593 static int param_set_lid_init_state(const char *val,
 594                                     const struct kernel_param *kp)
 595 {
 596         int i;
 597
 598         i = sysfs_match_string(lid_init_state_str, val);
 599         if (i < 0)
 600                 return i;
 601
 602         lid_init_state = i;
 603         pr_info("Initial lid state set to '%s'\n", lid_init_state_str[i]);
 604         return 0;
 605 }
 606
 607 static int param_get_lid_init_state(char *buf, const struct kernel_param *kp)
 608 {
 609         int i, c = 0;
 610
 611         for (i = 0; i < ARRAY_SIZE(lid_init_state_str); i++)
 612                 if (i == lid_init_state)
 613                         c += sprintf(buf + c, "[%s] ", lid_init_state_str[i]);
 614                 else
 615                         c += sprintf(buf + c, "%s ", lid_init_state_str[i]);
 616
 617         buf[c - 1] = '\n'; /* Replace the final space with a newline */
 618
 619         return c;
 620 }
 621
 622 module_param_call(lid_init_state,
 623                   param_set_lid_init_state, param_get_lid_init_state,
 624                   NULL, 0644);
 625 MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");
 626
 627 static int acpi_button_register_driver(struct acpi_driver *driver)
 628 {
 629         const struct dmi_system_id *dmi_id;
 630
 631         if (lid_init_state == -1) {
 632                 dmi_id = dmi_first_match(dmi_lid_quirks);
 633                 if (dmi_id)
 634                         lid_init_state = (long)dmi_id->driver_data;
 635                 else
 636                         lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
 637         }
 638
 639         /*
 640          * Modules such as nouveau.ko and i915.ko have a link time dependency
 641          * on acpi_lid_open(), and would therefore not be loadable on ACPI
 642          * capable kernels booted in non-ACPI mode if the return value of
 643          * acpi_bus_register_driver() is returned from here with ACPI disabled
 644          * when this driver is built as a module.
 645          */
 646         if (acpi_disabled)
 647                 return 0;
 648
 649         return acpi_bus_register_driver(driver);
 650 }
 651
 652 static void acpi_button_unregister_driver(struct acpi_driver *driver)
 653 {
 654         if (!acpi_disabled)
 655                 acpi_bus_unregister_driver(driver);
 656 }
 657
 658 module_driver(acpi_button_driver, acpi_button_register_driver,
 659                acpi_button_unregister_driver);