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