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 PREFIX "ACPI: "
  25
  26 #define ACPI_BUTTON_CLASS               "button"
  27 #define ACPI_BUTTON_FILE_INFO           "info"
  28 #define ACPI_BUTTON_FILE_STATE          "state"
  29 #define ACPI_BUTTON_TYPE_UNKNOWN        0x00
  30 #define ACPI_BUTTON_NOTIFY_STATUS       0x80
  31
  32 #define ACPI_BUTTON_SUBCLASS_POWER      "power"
  33 #define ACPI_BUTTON_HID_POWER           "PNP0C0C"
  34 #define ACPI_BUTTON_DEVICE_NAME_POWER   "Power Button"
  35 #define ACPI_BUTTON_TYPE_POWER          0x01
  36
  37 #define ACPI_BUTTON_SUBCLASS_SLEEP      "sleep"
  38 #define ACPI_BUTTON_HID_SLEEP           "PNP0C0E"
  39 #define ACPI_BUTTON_DEVICE_NAME_SLEEP   "Sleep Button"
  40 #define ACPI_BUTTON_TYPE_SLEEP          0x03
  41
  42 #define ACPI_BUTTON_SUBCLASS_LID        "lid"
  43 #define ACPI_BUTTON_HID_LID             "PNP0C0D"
  44 #define ACPI_BUTTON_DEVICE_NAME_LID     "Lid Switch"
  45 #define ACPI_BUTTON_TYPE_LID            0x05
  46
  47 enum {
  48         ACPI_BUTTON_LID_INIT_IGNORE,
  49         ACPI_BUTTON_LID_INIT_OPEN,
  50         ACPI_BUTTON_LID_INIT_METHOD,
  51         ACPI_BUTTON_LID_INIT_DISABLED,
  52 };
  53
  54 static const char * const lid_init_state_str[] = {
  55         [ACPI_BUTTON_LID_INIT_IGNORE]           = "ignore",
  56         [ACPI_BUTTON_LID_INIT_OPEN]             = "open",
  57         [ACPI_BUTTON_LID_INIT_METHOD]           = "method",
  58         [ACPI_BUTTON_LID_INIT_DISABLED]         = "disabled",
  59 };
  60
  61 #define _COMPONENT              ACPI_BUTTON_COMPONENT
  62 ACPI_MODULE_NAME("button");
  63
  64 MODULE_AUTHOR("Paul Diefenbaugh");
  65 MODULE_DESCRIPTION("ACPI Button Driver");
  66 MODULE_LICENSE("GPL");
  67
  68 static const struct acpi_device_id button_device_ids[] = {
  69         {ACPI_BUTTON_HID_LID,    0},
  70         {ACPI_BUTTON_HID_SLEEP,  0},
  71         {ACPI_BUTTON_HID_SLEEPF, 0},
  72         {ACPI_BUTTON_HID_POWER,  0},
  73         {ACPI_BUTTON_HID_POWERF, 0},
  74         {"", 0},
  75 };
  76 MODULE_DEVICE_TABLE(acpi, button_device_ids);
  77
  78 /* Please keep this list sorted alphabetically by vendor and model */
  79 static const struct dmi_system_id dmi_lid_quirks[] = {
  80         {
  81                 /*
  82                  * Asus T200TA, _LID keeps reporting closed after every second
  83                  * openening of the lid. Causing immediate re-suspend after
  84                  * opening every other open. Using LID_INIT_OPEN fixes this.
  85                  */
  86                 .matches = {
  87                         DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
  88                         DMI_MATCH(DMI_PRODUCT_NAME, "T200TA"),
  89                 },
  90                 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
  91         },
  92         {
  93                 /* GP-electronic T701, _LID method points to a floating GPIO */
  94                 .matches = {
  95                         DMI_MATCH(DMI_SYS_VENDOR, "Insyde"),
  96                         DMI_MATCH(DMI_PRODUCT_NAME, "T701"),
  97                         DMI_MATCH(DMI_BIOS_VERSION, "BYT70A.YNCHENG.WIN.007"),
  98                 },
  99                 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_DISABLED,
 100         },
 101         {
 102                 /*
 103                  * Medion Akoya E2215T, notification of the LID device only
 104                  * happens on close, not on open and _LID always returns closed.
 105                  */
 106                 .matches = {
 107                         DMI_MATCH(DMI_SYS_VENDOR, "MEDION"),
 108                         DMI_MATCH(DMI_PRODUCT_NAME, "E2215T MD60198"),
 109                 },
 110                 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
 111         },
 112         {}
 113 };
 114
 115 static int acpi_button_add(struct acpi_device *device);
 116 static int acpi_button_remove(struct acpi_device *device);
 117 static void acpi_button_notify(struct acpi_device *device, u32 event);
 118
 119 #ifdef CONFIG_PM_SLEEP
 120 static int acpi_button_suspend(struct device *dev);
 121 static int acpi_button_resume(struct device *dev);
 122 #else
 123 #define acpi_button_suspend NULL
 124 #define acpi_button_resume NULL
 125 #endif
 126 static SIMPLE_DEV_PM_OPS(acpi_button_pm, acpi_button_suspend, acpi_button_resume);
 127
 128 static struct acpi_driver acpi_button_driver = {
 129         .name = "button",
 130         .class = ACPI_BUTTON_CLASS,
 131         .ids = button_device_ids,
 132         .ops = {
 133                 .add = acpi_button_add,
 134                 .remove = acpi_button_remove,
 135                 .notify = acpi_button_notify,
 136         },
 137         .drv.pm = &acpi_button_pm,
 138 };
 139
 140 struct acpi_button {
 141         unsigned int type;
 142         struct input_dev *input;
 143         char phys[32];                  /* for input device */
 144         unsigned long pushed;
 145         int last_state;
 146         ktime_t last_time;
 147         bool suspended;
 148 };
 149
 150 static struct acpi_device *lid_device;
 151 static long lid_init_state = -1;
 152
 153 static unsigned long lid_report_interval __read_mostly = 500;
 154 module_param(lid_report_interval, ulong, 0644);
 155 MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");
 156
 157 /* --------------------------------------------------------------------------
 158                               FS Interface (/proc)
 159    -------------------------------------------------------------------------- */
 160
 161 static struct proc_dir_entry *acpi_button_dir;
 162 static struct proc_dir_entry *acpi_lid_dir;
 163
 164 static int acpi_lid_evaluate_state(struct acpi_device *device)
 165 {
 166         unsigned long long lid_state;
 167         acpi_status status;
 168
 169         status = acpi_evaluate_integer(device->handle, "_LID", NULL, &lid_state);
 170         if (ACPI_FAILURE(status))
 171                 return -ENODEV;
 172
 173         return lid_state ? 1 : 0;
 174 }
 175
 176 static int acpi_lid_notify_state(struct acpi_device *device, int state)
 177 {
 178         struct acpi_button *button = acpi_driver_data(device);
 179         ktime_t next_report;
 180         bool do_update;
 181
 182         /*
 183          * In lid_init_state=ignore mode, if user opens/closes lid
 184          * frequently with "open" missing, and "last_time" is also updated
 185          * frequently, "close" cannot be delivered to the userspace.
 186          * So "last_time" is only updated after a timeout or an actual
 187          * switch.
 188          */
 189         if (lid_init_state != ACPI_BUTTON_LID_INIT_IGNORE ||
 190             button->last_state != !!state)
 191                 do_update = true;
 192         else
 193                 do_update = false;
 194
 195         next_report = ktime_add(button->last_time,
 196                                 ms_to_ktime(lid_report_interval));
 197         if (button->last_state == !!state &&
 198             ktime_after(ktime_get(), next_report)) {
 199                 /* Complain the buggy firmware */
 200                 pr_warn_once("The lid device is not compliant to SW_LID.\n");
 201
 202                 /*
 203                  * Send the unreliable complement switch event:
 204                  *
 205                  * On most platforms, the lid device is reliable. However
 206                  * there are exceptions:
 207                  * 1. Platforms returning initial lid state as "close" by
 208                  *    default after booting/resuming:
 209                  *     https://bugzilla.kernel.org/show_bug.cgi?id=89211
 210                  *     https://bugzilla.kernel.org/show_bug.cgi?id=106151
 211                  * 2. Platforms never reporting "open" events:
 212                  *     https://bugzilla.kernel.org/show_bug.cgi?id=106941
 213                  * On these buggy platforms, the usage model of the ACPI
 214                  * lid device actually is:
 215                  * 1. The initial returning value of _LID may not be
 216                  *    reliable.
 217                  * 2. The open event may not be reliable.
 218                  * 3. The close event is reliable.
 219                  *
 220                  * But SW_LID is typed as input switch event, the input
 221                  * layer checks if the event is redundant. Hence if the
 222                  * state is not switched, the userspace cannot see this
 223                  * platform triggered reliable event. By inserting a
 224                  * complement switch event, it then is guaranteed that the
 225                  * platform triggered reliable one can always be seen by
 226                  * the userspace.
 227                  */
 228                 if (lid_init_state == ACPI_BUTTON_LID_INIT_IGNORE) {
 229                         do_update = true;
 230                         /*
 231                          * Do generate complement switch event for "close"
 232                          * as "close" is reliable and wrong "open" won't
 233                          * trigger unexpected behaviors.
 234                          * Do not generate complement switch event for
 235                          * "open" as "open" is not reliable and wrong
 236                          * "close" will trigger unexpected behaviors.
 237                          */
 238                         if (!state) {
 239                                 input_report_switch(button->input,
 240                                                     SW_LID, state);
 241                                 input_sync(button->input);
 242                         }
 243                 }
 244         }
 245         /* Send the platform triggered reliable event */
 246         if (do_update) {
 247                 acpi_handle_debug(device->handle, "ACPI LID %s\n",
 248                                   state ? "open" : "closed");
 249                 input_report_switch(button->input, SW_LID, !state);
 250                 input_sync(button->input);
 251                 button->last_state = !!state;
 252                 button->last_time = ktime_get();
 253         }
 254
 255         return 0;
 256 }
 257
 258 static int __maybe_unused acpi_button_state_seq_show(struct seq_file *seq,
 259                                                      void *offset)
 260 {
 261         struct acpi_device *device = seq->private;
 262         int state;
 263
 264         state = acpi_lid_evaluate_state(device);
 265         seq_printf(seq, "state:      %s\n",
 266                    state < 0 ? "unsupported" : (state ? "open" : "closed"));
 267         return 0;
 268 }
 269
 270 static int acpi_button_add_fs(struct acpi_device *device)
 271 {
 272         struct acpi_button *button = acpi_driver_data(device);
 273         struct proc_dir_entry *entry = NULL;
 274         int ret = 0;
 275
 276         /* procfs I/F for ACPI lid device only */
 277         if (button->type != ACPI_BUTTON_TYPE_LID)
 278                 return 0;
 279
 280         if (acpi_button_dir || acpi_lid_dir) {
 281                 printk(KERN_ERR PREFIX "More than one Lid device found!\n");
 282                 return -EEXIST;
 283         }
 284
 285         /* create /proc/acpi/button */
 286         acpi_button_dir = proc_mkdir(ACPI_BUTTON_CLASS, acpi_root_dir);
 287         if (!acpi_button_dir)
 288                 return -ENODEV;
 289
 290         /* create /proc/acpi/button/lid */
 291         acpi_lid_dir = proc_mkdir(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
 292         if (!acpi_lid_dir) {
 293                 ret = -ENODEV;
 294                 goto remove_button_dir;
 295         }
 296
 297         /* create /proc/acpi/button/lid/LID/ */
 298         acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device), acpi_lid_dir);
 299         if (!acpi_device_dir(device)) {
 300                 ret = -ENODEV;
 301                 goto remove_lid_dir;
 302         }
 303
 304         /* create /proc/acpi/button/lid/LID/state */
 305         entry = proc_create_single_data(ACPI_BUTTON_FILE_STATE, S_IRUGO,
 306                         acpi_device_dir(device), acpi_button_state_seq_show,
 307                         device);
 308         if (!entry) {
 309                 ret = -ENODEV;
 310                 goto remove_dev_dir;
 311         }
 312
 313 done:
 314         return ret;
 315
 316 remove_dev_dir:
 317         remove_proc_entry(acpi_device_bid(device),
 318                           acpi_lid_dir);
 319         acpi_device_dir(device) = NULL;
 320 remove_lid_dir:
 321         remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
 322         acpi_lid_dir = NULL;
 323 remove_button_dir:
 324         remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
 325         acpi_button_dir = NULL;
 326         goto done;
 327 }
 328
 329 static int acpi_button_remove_fs(struct acpi_device *device)
 330 {
 331         struct acpi_button *button = acpi_driver_data(device);
 332
 333         if (button->type != ACPI_BUTTON_TYPE_LID)
 334                 return 0;
 335
 336         remove_proc_entry(ACPI_BUTTON_FILE_STATE,
 337                           acpi_device_dir(device));
 338         remove_proc_entry(acpi_device_bid(device),
 339                           acpi_lid_dir);
 340         acpi_device_dir(device) = NULL;
 341         remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
 342         acpi_lid_dir = NULL;
 343         remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
 344         acpi_button_dir = NULL;
 345
 346         return 0;
 347 }
 348
 349 /* --------------------------------------------------------------------------
 350                                 Driver Interface
 351    -------------------------------------------------------------------------- */
 352 int acpi_lid_open(void)
 353 {
 354         if (!lid_device)
 355                 return -ENODEV;
 356
 357         return acpi_lid_evaluate_state(lid_device);
 358 }
 359 EXPORT_SYMBOL(acpi_lid_open);
 360
 361 static int acpi_lid_update_state(struct acpi_device *device,
 362                                  bool signal_wakeup)
 363 {
 364         int state;
 365
 366         state = acpi_lid_evaluate_state(device);
 367         if (state < 0)
 368                 return state;
 369
 370         if (state && signal_wakeup)
 371                 acpi_pm_wakeup_event(&device->dev);
 372
 373         return acpi_lid_notify_state(device, state);
 374 }
 375
 376 static void acpi_lid_initialize_state(struct acpi_device *device)
 377 {
 378         switch (lid_init_state) {
 379         case ACPI_BUTTON_LID_INIT_OPEN:
 380                 (void)acpi_lid_notify_state(device, 1);
 381                 break;
 382         case ACPI_BUTTON_LID_INIT_METHOD:
 383                 (void)acpi_lid_update_state(device, false);
 384                 break;
 385         case ACPI_BUTTON_LID_INIT_IGNORE:
 386         default:
 387                 break;
 388         }
 389 }
 390
 391 static void acpi_button_notify(struct acpi_device *device, u32 event)
 392 {
 393         struct acpi_button *button = acpi_driver_data(device);
 394         struct input_dev *input;
 395         int users;
 396
 397         switch (event) {
 398         case ACPI_FIXED_HARDWARE_EVENT:
 399                 event = ACPI_BUTTON_NOTIFY_STATUS;
 400                 /* fall through */
 401         case ACPI_BUTTON_NOTIFY_STATUS:
 402                 input = button->input;
 403                 if (button->type == ACPI_BUTTON_TYPE_LID) {
 404                         mutex_lock(&button->input->mutex);
 405                         users = button->input->users;
 406                         mutex_unlock(&button->input->mutex);
 407                         if (users)
 408                                 acpi_lid_update_state(device, true);
 409                 } else {
 410                         int keycode;
 411
 412                         acpi_pm_wakeup_event(&device->dev);
 413                         if (button->suspended)
 414                                 break;
 415
 416                         keycode = test_bit(KEY_SLEEP, input->keybit) ?
 417                                                 KEY_SLEEP : KEY_POWER;
 418                         input_report_key(input, keycode, 1);
 419                         input_sync(input);
 420                         input_report_key(input, keycode, 0);
 421                         input_sync(input);
 422
 423                         acpi_bus_generate_netlink_event(
 424                                         device->pnp.device_class,
 425                                         dev_name(&device->dev),
 426                                         event, ++button->pushed);
 427                 }
 428                 break;
 429         default:
 430                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 431                                   "Unsupported event [0x%x]\n", event));
 432                 break;
 433         }
 434 }
 435
 436 #ifdef CONFIG_PM_SLEEP
 437 static int acpi_button_suspend(struct device *dev)
 438 {
 439         struct acpi_device *device = to_acpi_device(dev);
 440         struct acpi_button *button = acpi_driver_data(device);
 441
 442         button->suspended = true;
 443         return 0;
 444 }
 445
 446 static int acpi_button_resume(struct device *dev)
 447 {
 448         struct acpi_device *device = to_acpi_device(dev);
 449         struct acpi_button *button = acpi_driver_data(device);
 450
 451         button->suspended = false;
 452         if (button->type == ACPI_BUTTON_TYPE_LID && button->input->users) {
 453                 button->last_state = !!acpi_lid_evaluate_state(device);
 454                 button->last_time = ktime_get();
 455                 acpi_lid_initialize_state(device);
 456         }
 457         return 0;
 458 }
 459 #endif
 460
 461 static int acpi_lid_input_open(struct input_dev *input)
 462 {
 463         struct acpi_device *device = input_get_drvdata(input);
 464         struct acpi_button *button = acpi_driver_data(device);
 465
 466         button->last_state = !!acpi_lid_evaluate_state(device);
 467         button->last_time = ktime_get();
 468         acpi_lid_initialize_state(device);
 469
 470         return 0;
 471 }
 472
 473 static int acpi_button_add(struct acpi_device *device)
 474 {
 475         struct acpi_button *button;
 476         struct input_dev *input;
 477         const char *hid = acpi_device_hid(device);
 478         char *name, *class;
 479         int error;
 480
 481         if (!strcmp(hid, ACPI_BUTTON_HID_LID) &&
 482              lid_init_state == ACPI_BUTTON_LID_INIT_DISABLED)
 483                 return -ENODEV;
 484
 485         button = kzalloc(sizeof(struct acpi_button), GFP_KERNEL);
 486         if (!button)
 487                 return -ENOMEM;
 488
 489         device->driver_data = button;
 490
 491         button->input = input = input_allocate_device();
 492         if (!input) {
 493                 error = -ENOMEM;
 494                 goto err_free_button;
 495         }
 496
 497         name = acpi_device_name(device);
 498         class = acpi_device_class(device);
 499
 500         if (!strcmp(hid, ACPI_BUTTON_HID_POWER) ||
 501             !strcmp(hid, ACPI_BUTTON_HID_POWERF)) {
 502                 button->type = ACPI_BUTTON_TYPE_POWER;
 503                 strcpy(name, ACPI_BUTTON_DEVICE_NAME_POWER);
 504                 sprintf(class, "%s/%s",
 505                         ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_POWER);
 506         } else if (!strcmp(hid, ACPI_BUTTON_HID_SLEEP) ||
 507                    !strcmp(hid, ACPI_BUTTON_HID_SLEEPF)) {
 508                 button->type = ACPI_BUTTON_TYPE_SLEEP;
 509                 strcpy(name, ACPI_BUTTON_DEVICE_NAME_SLEEP);
 510                 sprintf(class, "%s/%s",
 511                         ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_SLEEP);
 512         } else if (!strcmp(hid, ACPI_BUTTON_HID_LID)) {
 513                 button->type = ACPI_BUTTON_TYPE_LID;
 514                 strcpy(name, ACPI_BUTTON_DEVICE_NAME_LID);
 515                 sprintf(class, "%s/%s",
 516                         ACPI_BUTTON_CLASS, ACPI_BUTTON_SUBCLASS_LID);
 517                 input->open = acpi_lid_input_open;
 518         } else {
 519                 printk(KERN_ERR PREFIX "Unsupported hid [%s]\n", hid);
 520                 error = -ENODEV;
 521                 goto err_free_input;
 522         }
 523
 524         error = acpi_button_add_fs(device);
 525         if (error)
 526                 goto err_free_input;
 527
 528         snprintf(button->phys, sizeof(button->phys), "%s/button/input0", hid);
 529
 530         input->name = name;
 531         input->phys = button->phys;
 532         input->id.bustype = BUS_HOST;
 533         input->id.product = button->type;
 534         input->dev.parent = &device->dev;
 535
 536         switch (button->type) {
 537         case ACPI_BUTTON_TYPE_POWER:
 538                 input_set_capability(input, EV_KEY, KEY_POWER);
 539                 break;
 540
 541         case ACPI_BUTTON_TYPE_SLEEP:
 542                 input_set_capability(input, EV_KEY, KEY_SLEEP);
 543                 break;
 544
 545         case ACPI_BUTTON_TYPE_LID:
 546                 input_set_capability(input, EV_SW, SW_LID);
 547                 break;
 548         }
 549
 550         input_set_drvdata(input, device);
 551         error = input_register_device(input);
 552         if (error)
 553                 goto err_remove_fs;
 554         if (button->type == ACPI_BUTTON_TYPE_LID) {
 555                 /*
 556                  * This assumes there's only one lid device, or if there are
 557                  * more we only care about the last one...
 558                  */
 559                 lid_device = device;
 560         }
 561
 562         device_init_wakeup(&device->dev, true);
 563         printk(KERN_INFO PREFIX "%s [%s]\n", name, acpi_device_bid(device));
 564         return 0;
 565
 566  err_remove_fs:
 567         acpi_button_remove_fs(device);
 568  err_free_input:
 569         input_free_device(input);
 570  err_free_button:
 571         kfree(button);
 572         return error;
 573 }
 574
 575 static int acpi_button_remove(struct acpi_device *device)
 576 {
 577         struct acpi_button *button = acpi_driver_data(device);
 578
 579         acpi_button_remove_fs(device);
 580         input_unregister_device(button->input);
 581         kfree(button);
 582         return 0;
 583 }
 584
 585 static int param_set_lid_init_state(const char *val,
 586                                     const struct kernel_param *kp)
 587 {
 588         int i;
 589
 590         i = sysfs_match_string(lid_init_state_str, val);
 591         if (i < 0)
 592                 return i;
 593
 594         lid_init_state = i;
 595         pr_info("Initial lid state set to '%s'\n", lid_init_state_str[i]);
 596         return 0;
 597 }
 598
 599 static int param_get_lid_init_state(char *buf, const struct kernel_param *kp)
 600 {
 601         int i, c = 0;
 602
 603         for (i = 0; i < ARRAY_SIZE(lid_init_state_str); i++)
 604                 if (i == lid_init_state)
 605                         c += sprintf(buf + c, "[%s] ", lid_init_state_str[i]);
 606                 else
 607                         c += sprintf(buf + c, "%s ", lid_init_state_str[i]);
 608
 609         buf[c - 1] = '\n'; /* Replace the final space with a newline */
 610
 611         return c;
 612 }
 613
 614 module_param_call(lid_init_state,
 615                   param_set_lid_init_state, param_get_lid_init_state,
 616                   NULL, 0644);
 617 MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");
 618
 619 static int acpi_button_register_driver(struct acpi_driver *driver)
 620 {
 621         const struct dmi_system_id *dmi_id;
 622
 623         if (lid_init_state == -1) {
 624                 dmi_id = dmi_first_match(dmi_lid_quirks);
 625                 if (dmi_id)
 626                         lid_init_state = (long)dmi_id->driver_data;
 627                 else
 628                         lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
 629         }
 630
 631         /*
 632          * Modules such as nouveau.ko and i915.ko have a link time dependency
 633          * on acpi_lid_open(), and would therefore not be loadable on ACPI
 634          * capable kernels booted in non-ACPI mode if the return value of
 635          * acpi_bus_register_driver() is returned from here with ACPI disabled
 636          * when this driver is built as a module.
 637          */
 638         if (acpi_disabled)
 639                 return 0;
 640
 641         return acpi_bus_register_driver(driver);
 642 }
 643
 644 static void acpi_button_unregister_driver(struct acpi_driver *driver)
 645 {
 646         if (!acpi_disabled)
 647                 acpi_bus_unregister_driver(driver);
 648 }
 649
 650 module_driver(acpi_button_driver, acpi_button_register_driver,
 651                acpi_button_unregister_driver);