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                 /*
  78                  * Acer Switch 10 SW5-012. _LID method messes with home and
  79                  * power button GPIO IRQ settings causing an interrupt storm on
  80                  * both GPIOs. This is unfixable without a DSDT override, so we
  81                  * have to disable the lid-switch functionality altogether :|
  82                  */
  83                 .matches = {
  84                         DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
  85                         DMI_MATCH(DMI_PRODUCT_NAME, "Aspire SW5-012"),
  86                 },
  87                 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_DISABLED,
  88         },
  89         {
  90                 /* GP-electronic T701, _LID method points to a floating GPIO */
  91                 .matches = {
  92                         DMI_MATCH(DMI_SYS_VENDOR, "Insyde"),
  93                         DMI_MATCH(DMI_PRODUCT_NAME, "T701"),
  94                         DMI_MATCH(DMI_BIOS_VERSION, "BYT70A.YNCHENG.WIN.007"),
  95                 },
  96                 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_DISABLED,
  97         },
  98         {
  99                 /*
 100                  * Medion Akoya E2215T, notification of the LID device only
 101                  * happens on close, not on open and _LID always returns closed.
 102                  */
 103                 .matches = {
 104                         DMI_MATCH(DMI_SYS_VENDOR, "MEDION"),
 105                         DMI_MATCH(DMI_PRODUCT_NAME, "E2215T MD60198"),
 106                 },
 107                 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
 108         },
 109         {
 110                 /*
 111                  * Razer Blade Stealth 13 late 2019, notification of the LID device
 112                  * only happens on close, not on open and _LID always returns closed.
 113                  */
 114                 .matches = {
 115                         DMI_MATCH(DMI_SYS_VENDOR, "Razer"),
 116                         DMI_MATCH(DMI_PRODUCT_NAME, "Razer Blade Stealth 13 Late 2019"),
 117                 },
 118                 .driver_data = (void *)(long)ACPI_BUTTON_LID_INIT_OPEN,
 119         },
 120         {}
 121 };
 122
 123 static int acpi_button_add(struct acpi_device *device);
 124 static int acpi_button_remove(struct acpi_device *device);
 125 static void acpi_button_notify(struct acpi_device *device, u32 event);
 126
 127 #ifdef CONFIG_PM_SLEEP
 128 static int acpi_button_suspend(struct device *dev);
 129 static int acpi_button_resume(struct device *dev);
 130 #else
 131 #define acpi_button_suspend NULL
 132 #define acpi_button_resume NULL
 133 #endif
 134 static SIMPLE_DEV_PM_OPS(acpi_button_pm, acpi_button_suspend, acpi_button_resume);
 135
 136 static struct acpi_driver acpi_button_driver = {
 137         .name = "button",
 138         .class = ACPI_BUTTON_CLASS,
 139         .ids = button_device_ids,
 140         .ops = {
 141                 .add = acpi_button_add,
 142                 .remove = acpi_button_remove,
 143                 .notify = acpi_button_notify,
 144         },
 145         .drv.pm = &acpi_button_pm,
 146 };
 147
 148 struct acpi_button {
 149         unsigned int type;
 150         struct input_dev *input;
 151         char phys[32];                  /* for input device */
 152         unsigned long pushed;
 153         int last_state;
 154         ktime_t last_time;
 155         bool suspended;
 156 };
 157
 158 static struct acpi_device *lid_device;
 159 static long lid_init_state = -1;
 160
 161 static unsigned long lid_report_interval __read_mostly = 500;
 162 module_param(lid_report_interval, ulong, 0644);
 163 MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");
 164
 165 /* --------------------------------------------------------------------------
 166                               FS Interface (/proc)
 167    -------------------------------------------------------------------------- */
 168
 169 static struct proc_dir_entry *acpi_button_dir;
 170 static struct proc_dir_entry *acpi_lid_dir;
 171
 172 static int acpi_lid_evaluate_state(struct acpi_device *device)
 173 {
 174         unsigned long long lid_state;
 175         acpi_status status;
 176
 177         status = acpi_evaluate_integer(device->handle, "_LID", NULL, &lid_state);
 178         if (ACPI_FAILURE(status))
 179                 return -ENODEV;
 180
 181         return lid_state ? 1 : 0;
 182 }
 183
 184 static int acpi_lid_notify_state(struct acpi_device *device, int state)
 185 {
 186         struct acpi_button *button = acpi_driver_data(device);
 187         ktime_t next_report;
 188         bool do_update;
 189
 190         /*
 191          * In lid_init_state=ignore mode, if user opens/closes lid
 192          * frequently with "open" missing, and "last_time" is also updated
 193          * frequently, "close" cannot be delivered to the userspace.
 194          * So "last_time" is only updated after a timeout or an actual
 195          * switch.
 196          */
 197         if (lid_init_state != ACPI_BUTTON_LID_INIT_IGNORE ||
 198             button->last_state != !!state)
 199                 do_update = true;
 200         else
 201                 do_update = false;
 202
 203         next_report = ktime_add(button->last_time,
 204                                 ms_to_ktime(lid_report_interval));
 205         if (button->last_state == !!state &&
 206             ktime_after(ktime_get(), next_report)) {
 207                 /* Complain the buggy firmware */
 208                 pr_warn_once("The lid device is not compliant to SW_LID.\n");
 209
 210                 /*
 211                  * Send the unreliable complement switch event:
 212                  *
 213                  * On most platforms, the lid device is reliable. However
 214                  * there are exceptions:
 215                  * 1. Platforms returning initial lid state as "close" by
 216                  *    default after booting/resuming:
 217                  *     https://bugzilla.kernel.org/show_bug.cgi?id=89211
 218                  *     https://bugzilla.kernel.org/show_bug.cgi?id=106151
 219                  * 2. Platforms never reporting "open" events:
 220                  *     https://bugzilla.kernel.org/show_bug.cgi?id=106941
 221                  * On these buggy platforms, the usage model of the ACPI
 222                  * lid device actually is:
 223                  * 1. The initial returning value of _LID may not be
 224                  *    reliable.
 225                  * 2. The open event may not be reliable.
 226                  * 3. The close event is reliable.
 227                  *
 228                  * But SW_LID is typed as input switch event, the input
 229                  * layer checks if the event is redundant. Hence if the
 230                  * state is not switched, the userspace cannot see this
 231                  * platform triggered reliable event. By inserting a
 232                  * complement switch event, it then is guaranteed that the
 233                  * platform triggered reliable one can always be seen by
 234                  * the userspace.
 235                  */
 236                 if (lid_init_state == ACPI_BUTTON_LID_INIT_IGNORE) {
 237                         do_update = true;
 238                         /*
 239                          * Do generate complement switch event for "close"
 240                          * as "close" is reliable and wrong "open" won't
 241                          * trigger unexpected behaviors.
 242                          * Do not generate complement switch event for
 243                          * "open" as "open" is not reliable and wrong
 244                          * "close" will trigger unexpected behaviors.
 245                          */
 246                         if (!state) {
 247                                 input_report_switch(button->input,
 248                                                     SW_LID, state);
 249                                 input_sync(button->input);
 250                         }
 251                 }
 252         }
 253         /* Send the platform triggered reliable event */
 254         if (do_update) {
 255                 acpi_handle_debug(device->handle, "ACPI LID %s\n",
 256                                   state ? "open" : "closed");
 257                 input_report_switch(button->input, SW_LID, !state);
 258                 input_sync(button->input);
 259                 button->last_state = !!state;
 260                 button->last_time = ktime_get();
 261         }
 262
 263         return 0;
 264 }
 265
 266 static int __maybe_unused acpi_button_state_seq_show(struct seq_file *seq,
 267                                                      void *offset)
 268 {
 269         struct acpi_device *device = seq->private;
 270         int state;
 271
 272         state = acpi_lid_evaluate_state(device);
 273         seq_printf(seq, "state:      %s\n",
 274                    state < 0 ? "unsupported" : (state ? "open" : "closed"));
 275         return 0;
 276 }
 277
 278 static int acpi_button_add_fs(struct acpi_device *device)
 279 {
 280         struct acpi_button *button = acpi_driver_data(device);
 281         struct proc_dir_entry *entry = NULL;
 282         int ret = 0;
 283
 284         /* procfs I/F for ACPI lid device only */
 285         if (button->type != ACPI_BUTTON_TYPE_LID)
 286                 return 0;
 287
 288         if (acpi_button_dir || acpi_lid_dir) {
 289                 printk(KERN_ERR PREFIX "More than one Lid device found!\n");
 290                 return -EEXIST;
 291         }
 292
 293         /* create /proc/acpi/button */
 294         acpi_button_dir = proc_mkdir(ACPI_BUTTON_CLASS, acpi_root_dir);
 295         if (!acpi_button_dir)
 296                 return -ENODEV;
 297
 298         /* create /proc/acpi/button/lid */
 299         acpi_lid_dir = proc_mkdir(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
 300         if (!acpi_lid_dir) {
 301                 ret = -ENODEV;
 302                 goto remove_button_dir;
 303         }
 304
 305         /* create /proc/acpi/button/lid/LID/ */
 306         acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device), acpi_lid_dir);
 307         if (!acpi_device_dir(device)) {
 308                 ret = -ENODEV;
 309                 goto remove_lid_dir;
 310         }
 311
 312         /* create /proc/acpi/button/lid/LID/state */
 313         entry = proc_create_single_data(ACPI_BUTTON_FILE_STATE, S_IRUGO,
 314                         acpi_device_dir(device), acpi_button_state_seq_show,
 315                         device);
 316         if (!entry) {
 317                 ret = -ENODEV;
 318                 goto remove_dev_dir;
 319         }
 320
 321 done:
 322         return ret;
 323
 324 remove_dev_dir:
 325         remove_proc_entry(acpi_device_bid(device),
 326                           acpi_lid_dir);
 327         acpi_device_dir(device) = NULL;
 328 remove_lid_dir:
 329         remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
 330         acpi_lid_dir = NULL;
 331 remove_button_dir:
 332         remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
 333         acpi_button_dir = NULL;
 334         goto done;
 335 }
 336
 337 static int acpi_button_remove_fs(struct acpi_device *device)
 338 {
 339         struct acpi_button *button = acpi_driver_data(device);
 340
 341         if (button->type != ACPI_BUTTON_TYPE_LID)
 342                 return 0;
 343
 344         remove_proc_entry(ACPI_BUTTON_FILE_STATE,
 345                           acpi_device_dir(device));
 346         remove_proc_entry(acpi_device_bid(device),
 347                           acpi_lid_dir);
 348         acpi_device_dir(device) = NULL;
 349         remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
 350         acpi_lid_dir = NULL;
 351         remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
 352         acpi_button_dir = NULL;
 353
 354         return 0;
 355 }
 356
 357 /* --------------------------------------------------------------------------
 358                                 Driver Interface
 359    -------------------------------------------------------------------------- */
 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         switch (lid_init_state) {
 387         case ACPI_BUTTON_LID_INIT_OPEN:
 388                 (void)acpi_lid_notify_state(device, 1);
 389                 break;
 390         case ACPI_BUTTON_LID_INIT_METHOD:
 391                 (void)acpi_lid_update_state(device, false);
 392                 break;
 393         case ACPI_BUTTON_LID_INIT_IGNORE:
 394         default:
 395                 break;
 396         }
 397 }
 398
 399 static void acpi_button_notify(struct acpi_device *device, u32 event)
 400 {
 401         struct acpi_button *button = acpi_driver_data(device);
 402         struct input_dev *input;
 403         int users;
 404
 405         switch (event) {
 406         case ACPI_FIXED_HARDWARE_EVENT:
 407                 event = ACPI_BUTTON_NOTIFY_STATUS;
 408                 /* fall through */
 409         case ACPI_BUTTON_NOTIFY_STATUS:
 410                 input = button->input;
 411                 if (button->type == ACPI_BUTTON_TYPE_LID) {
 412                         mutex_lock(&button->input->mutex);
 413                         users = button->input->users;
 414                         mutex_unlock(&button->input->mutex);
 415                         if (users)
 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_DEBUG_PRINT((ACPI_DB_INFO,
 439                                   "Unsupported event [0x%x]\n", 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 && button->input->users) {
 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                 printk(KERN_ERR PREFIX "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         printk(KERN_INFO PREFIX "%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);