drivers/acpi/button.c

   1 /*
   2  *  button.c - ACPI Button Driver
   3  *
   4  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
   5  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
   6  *
   7  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License as published by
  11  *  the Free Software Foundation; either version 2 of the License, or (at
  12  *  your option) any later version.
  13  *
  14  *  This program is distributed in the hope that it will be useful, but
  15  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  *  General Public License for more details.
  18  *
  19  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  20  */
  21
  22 #define pr_fmt(fmt) "ACPI: button: " fmt
  23
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/init.h>
  27 #include <linux/types.h>
  28 #include <linux/proc_fs.h>
  29 #include <linux/seq_file.h>
  30 #include <linux/input.h>
  31 #include <linux/slab.h>
  32 #include <linux/acpi.h>
  33 #include <linux/dmi.h>
  34 #include <acpi/button.h>
  35
  36 #define PREFIX "ACPI: "
  37
  38 #define ACPI_BUTTON_CLASS               "button"
  39 #define ACPI_BUTTON_FILE_INFO           "info"
  40 #define ACPI_BUTTON_FILE_STATE          "state"
  41 #define ACPI_BUTTON_TYPE_UNKNOWN        0x00
  42 #define ACPI_BUTTON_NOTIFY_STATUS       0x80
  43
  44 #define ACPI_BUTTON_SUBCLASS_POWER      "power"
  45 #define ACPI_BUTTON_HID_POWER           "PNP0C0C"
  46 #define ACPI_BUTTON_DEVICE_NAME_POWER   "Power Button"
  47 #define ACPI_BUTTON_TYPE_POWER          0x01
  48
  49 #define ACPI_BUTTON_SUBCLASS_SLEEP      "sleep"
  50 #define ACPI_BUTTON_HID_SLEEP           "PNP0C0E"
  51 #define ACPI_BUTTON_DEVICE_NAME_SLEEP   "Sleep Button"
  52 #define ACPI_BUTTON_TYPE_SLEEP          0x03
  53
  54 #define ACPI_BUTTON_SUBCLASS_LID        "lid"
  55 #define ACPI_BUTTON_HID_LID             "PNP0C0D"
  56 #define ACPI_BUTTON_DEVICE_NAME_LID     "Lid Switch"
  57 #define ACPI_BUTTON_TYPE_LID            0x05
  58
  59 #define ACPI_BUTTON_LID_INIT_IGNORE     0x00
  60 #define ACPI_BUTTON_LID_INIT_OPEN       0x01
  61 #define ACPI_BUTTON_LID_INIT_METHOD     0x02
  62
  63 #define _COMPONENT              ACPI_BUTTON_COMPONENT
  64 ACPI_MODULE_NAME("button");
  65
  66 MODULE_AUTHOR("Paul Diefenbaugh");
  67 MODULE_DESCRIPTION("ACPI Button Driver");
  68 MODULE_LICENSE("GPL");
  69
  70 static const struct acpi_device_id button_device_ids[] = {
  71         {ACPI_BUTTON_HID_LID,    0},
  72         {ACPI_BUTTON_HID_SLEEP,  0},
  73         {ACPI_BUTTON_HID_SLEEPF, 0},
  74         {ACPI_BUTTON_HID_POWER,  0},
  75         {ACPI_BUTTON_HID_POWERF, 0},
  76         {"", 0},
  77 };
  78 MODULE_DEVICE_TABLE(acpi, button_device_ids);
  79
  80 /*
  81  * Some devices which don't even have a lid in anyway have a broken _LID
  82  * method (e.g. pointing to a floating gpio pin) causing spurious LID events.
  83  */
  84 static const struct dmi_system_id lid_blacklst[] = {
  85         {
  86                 /* GP-electronic T701 */
  87                 .matches = {
  88                         DMI_MATCH(DMI_SYS_VENDOR, "Insyde"),
  89                         DMI_MATCH(DMI_PRODUCT_NAME, "T701"),
  90                         DMI_MATCH(DMI_BIOS_VERSION, "BYT70A.YNCHENG.WIN.007"),
  91                 },
  92         },
  93         {}
  94 };
  95
  96 static int acpi_button_add(struct acpi_device *device);
  97 static int acpi_button_remove(struct acpi_device *device);
  98 static void acpi_button_notify(struct acpi_device *device, u32 event);
  99
 100 #ifdef CONFIG_PM_SLEEP
 101 static int acpi_button_suspend(struct device *dev);
 102 static int acpi_button_resume(struct device *dev);
 103 #else
 104 #define acpi_button_suspend NULL
 105 #define acpi_button_resume NULL
 106 #endif
 107 static SIMPLE_DEV_PM_OPS(acpi_button_pm, acpi_button_suspend, acpi_button_resume);
 108
 109 static struct acpi_driver acpi_button_driver = {
 110         .name = "button",
 111         .class = ACPI_BUTTON_CLASS,
 112         .ids = button_device_ids,
 113         .ops = {
 114                 .add = acpi_button_add,
 115                 .remove = acpi_button_remove,
 116                 .notify = acpi_button_notify,
 117         },
 118         .drv.pm = &acpi_button_pm,
 119 };
 120
 121 struct acpi_button {
 122         unsigned int type;
 123         struct input_dev *input;
 124         char phys[32];                  /* for input device */
 125         unsigned long pushed;
 126         int last_state;
 127         ktime_t last_time;
 128         bool suspended;
 129 };
 130
 131 static BLOCKING_NOTIFIER_HEAD(acpi_lid_notifier);
 132 static struct acpi_device *lid_device;
 133 static u8 lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
 134
 135 static unsigned long lid_report_interval __read_mostly = 500;
 136 module_param(lid_report_interval, ulong, 0644);
 137 MODULE_PARM_DESC(lid_report_interval, "Interval (ms) between lid key events");
 138
 139 /* --------------------------------------------------------------------------
 140                               FS Interface (/proc)
 141    -------------------------------------------------------------------------- */
 142
 143 static struct proc_dir_entry *acpi_button_dir;
 144 static struct proc_dir_entry *acpi_lid_dir;
 145
 146 static int acpi_lid_evaluate_state(struct acpi_device *device)
 147 {
 148         unsigned long long lid_state;
 149         acpi_status status;
 150
 151         status = acpi_evaluate_integer(device->handle, "_LID", NULL, &lid_state);
 152         if (ACPI_FAILURE(status))
 153                 return -ENODEV;
 154
 155         return lid_state ? 1 : 0;
 156 }
 157
 158 static int acpi_lid_notify_state(struct acpi_device *device, int state)
 159 {
 160         struct acpi_button *button = acpi_driver_data(device);
 161         int ret;
 162         ktime_t next_report;
 163         bool do_update;
 164
 165         /*
 166          * In lid_init_state=ignore mode, if user opens/closes lid
 167          * frequently with "open" missing, and "last_time" is also updated
 168          * frequently, "close" cannot be delivered to the userspace.
 169          * So "last_time" is only updated after a timeout or an actual
 170          * switch.
 171          */
 172         if (lid_init_state != ACPI_BUTTON_LID_INIT_IGNORE ||
 173             button->last_state != !!state)
 174                 do_update = true;
 175         else
 176                 do_update = false;
 177
 178         next_report = ktime_add(button->last_time,
 179                                 ms_to_ktime(lid_report_interval));
 180         if (button->last_state == !!state &&
 181             ktime_after(ktime_get(), next_report)) {
 182                 /* Complain the buggy firmware */
 183                 pr_warn_once("The lid device is not compliant to SW_LID.\n");
 184
 185                 /*
 186                  * Send the unreliable complement switch event:
 187                  *
 188                  * On most platforms, the lid device is reliable. However
 189                  * there are exceptions:
 190                  * 1. Platforms returning initial lid state as "close" by
 191                  *    default after booting/resuming:
 192                  *     https://bugzilla.kernel.org/show_bug.cgi?id=89211
 193                  *     https://bugzilla.kernel.org/show_bug.cgi?id=106151
 194                  * 2. Platforms never reporting "open" events:
 195                  *     https://bugzilla.kernel.org/show_bug.cgi?id=106941
 196                  * On these buggy platforms, the usage model of the ACPI
 197                  * lid device actually is:
 198                  * 1. The initial returning value of _LID may not be
 199                  *    reliable.
 200                  * 2. The open event may not be reliable.
 201                  * 3. The close event is reliable.
 202                  *
 203                  * But SW_LID is typed as input switch event, the input
 204                  * layer checks if the event is redundant. Hence if the
 205                  * state is not switched, the userspace cannot see this
 206                  * platform triggered reliable event. By inserting a
 207                  * complement switch event, it then is guaranteed that the
 208                  * platform triggered reliable one can always be seen by
 209                  * the userspace.
 210                  */
 211                 if (lid_init_state == ACPI_BUTTON_LID_INIT_IGNORE) {
 212                         do_update = true;
 213                         /*
 214                          * Do generate complement switch event for "close"
 215                          * as "close" is reliable and wrong "open" won't
 216                          * trigger unexpected behaviors.
 217                          * Do not generate complement switch event for
 218                          * "open" as "open" is not reliable and wrong
 219                          * "close" will trigger unexpected behaviors.
 220                          */
 221                         if (!state) {
 222                                 input_report_switch(button->input,
 223                                                     SW_LID, state);
 224                                 input_sync(button->input);
 225                         }
 226                 }
 227         }
 228         /* Send the platform triggered reliable event */
 229         if (do_update) {
 230                 acpi_handle_debug(device->handle, "ACPI LID %s\n",
 231                                   state ? "open" : "closed");
 232                 input_report_switch(button->input, SW_LID, !state);
 233                 input_sync(button->input);
 234                 button->last_state = !!state;
 235                 button->last_time = ktime_get();
 236         }
 237
 238         if (state)
 239                 acpi_pm_wakeup_event(&device->dev);
 240
 241         ret = blocking_notifier_call_chain(&acpi_lid_notifier, state, device);
 242         if (ret == NOTIFY_DONE)
 243                 ret = blocking_notifier_call_chain(&acpi_lid_notifier, state,
 244                                                    device);
 245         if (ret == NOTIFY_DONE || ret == NOTIFY_OK) {
 246                 /*
 247                  * It is also regarded as success if the notifier_chain
 248                  * returns NOTIFY_OK or NOTIFY_DONE.
 249                  */
 250                 ret = 0;
 251         }
 252         return ret;
 253 }
 254
 255 static int acpi_button_state_seq_show(struct seq_file *seq, void *offset)
 256 {
 257         struct acpi_device *device = seq->private;
 258         int state;
 259
 260         state = acpi_lid_evaluate_state(device);
 261         seq_printf(seq, "state:      %s\n",
 262                    state < 0 ? "unsupported" : (state ? "open" : "closed"));
 263         return 0;
 264 }
 265
 266 static int acpi_button_add_fs(struct acpi_device *device)
 267 {
 268         struct acpi_button *button = acpi_driver_data(device);
 269         struct proc_dir_entry *entry = NULL;
 270         int ret = 0;
 271
 272         /* procfs I/F for ACPI lid device only */
 273         if (button->type != ACPI_BUTTON_TYPE_LID)
 274                 return 0;
 275
 276         if (acpi_button_dir || acpi_lid_dir) {
 277                 printk(KERN_ERR PREFIX "More than one Lid device found!\n");
 278                 return -EEXIST;
 279         }
 280
 281         /* create /proc/acpi/button */
 282         acpi_button_dir = proc_mkdir(ACPI_BUTTON_CLASS, acpi_root_dir);
 283         if (!acpi_button_dir)
 284                 return -ENODEV;
 285
 286         /* create /proc/acpi/button/lid */
 287         acpi_lid_dir = proc_mkdir(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
 288         if (!acpi_lid_dir) {
 289                 ret = -ENODEV;
 290                 goto remove_button_dir;
 291         }
 292
 293         /* create /proc/acpi/button/lid/LID/ */
 294         acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device), acpi_lid_dir);
 295         if (!acpi_device_dir(device)) {
 296                 ret = -ENODEV;
 297                 goto remove_lid_dir;
 298         }
 299
 300         /* create /proc/acpi/button/lid/LID/state */
 301         entry = proc_create_single_data(ACPI_BUTTON_FILE_STATE, S_IRUGO,
 302                         acpi_device_dir(device), acpi_button_state_seq_show,
 303                         device);
 304         if (!entry) {
 305                 ret = -ENODEV;
 306                 goto remove_dev_dir;
 307         }
 308
 309 done:
 310         return ret;
 311
 312 remove_dev_dir:
 313         remove_proc_entry(acpi_device_bid(device),
 314                           acpi_lid_dir);
 315         acpi_device_dir(device) = NULL;
 316 remove_lid_dir:
 317         remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
 318         acpi_lid_dir = NULL;
 319 remove_button_dir:
 320         remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
 321         acpi_button_dir = NULL;
 322         goto done;
 323 }
 324
 325 static int acpi_button_remove_fs(struct acpi_device *device)
 326 {
 327         struct acpi_button *button = acpi_driver_data(device);
 328
 329         if (button->type != ACPI_BUTTON_TYPE_LID)
 330                 return 0;
 331
 332         remove_proc_entry(ACPI_BUTTON_FILE_STATE,
 333                           acpi_device_dir(device));
 334         remove_proc_entry(acpi_device_bid(device),
 335                           acpi_lid_dir);
 336         acpi_device_dir(device) = NULL;
 337         remove_proc_entry(ACPI_BUTTON_SUBCLASS_LID, acpi_button_dir);
 338         acpi_lid_dir = NULL;
 339         remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);
 340         acpi_button_dir = NULL;
 341
 342         return 0;
 343 }
 344
 345 /* --------------------------------------------------------------------------
 346                                 Driver Interface
 347    -------------------------------------------------------------------------- */
 348 int acpi_lid_notifier_register(struct notifier_block *nb)
 349 {
 350         return blocking_notifier_chain_register(&acpi_lid_notifier, nb);
 351 }
 352 EXPORT_SYMBOL(acpi_lid_notifier_register);
 353
 354 int acpi_lid_notifier_unregister(struct notifier_block *nb)
 355 {
 356         return blocking_notifier_chain_unregister(&acpi_lid_notifier, nb);
 357 }
 358 EXPORT_SYMBOL(acpi_lid_notifier_unregister);
 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 {
 371         int state;
 372
 373         state = acpi_lid_evaluate_state(device);
 374         if (state < 0)
 375                 return state;
 376
 377         return acpi_lid_notify_state(device, state);
 378 }
 379
 380 static void acpi_lid_initialize_state(struct acpi_device *device)
 381 {
 382         switch (lid_init_state) {
 383         case ACPI_BUTTON_LID_INIT_OPEN:
 384                 (void)acpi_lid_notify_state(device, 1);
 385                 break;
 386         case ACPI_BUTTON_LID_INIT_METHOD:
 387                 (void)acpi_lid_update_state(device);
 388                 break;
 389         case ACPI_BUTTON_LID_INIT_IGNORE:
 390         default:
 391                 break;
 392         }
 393 }
 394
 395 static void acpi_button_notify(struct acpi_device *device, u32 event)
 396 {
 397         struct acpi_button *button = acpi_driver_data(device);
 398         struct input_dev *input;
 399         int users;
 400
 401         switch (event) {
 402         case ACPI_FIXED_HARDWARE_EVENT:
 403                 event = ACPI_BUTTON_NOTIFY_STATUS;
 404                 /* fall through */
 405         case ACPI_BUTTON_NOTIFY_STATUS:
 406                 input = button->input;
 407                 if (button->type == ACPI_BUTTON_TYPE_LID) {
 408                         mutex_lock(&button->input->mutex);
 409                         users = button->input->users;
 410                         mutex_unlock(&button->input->mutex);
 411                         if (users)
 412                                 acpi_lid_update_state(device);
 413                 } else {
 414                         int keycode;
 415
 416                         acpi_pm_wakeup_event(&device->dev);
 417                         if (button->suspended)
 418                                 break;
 419
 420                         keycode = test_bit(KEY_SLEEP, input->keybit) ?
 421                                                 KEY_SLEEP : KEY_POWER;
 422                         input_report_key(input, keycode, 1);
 423                         input_sync(input);
 424                         input_report_key(input, keycode, 0);
 425                         input_sync(input);
 426
 427                         acpi_bus_generate_netlink_event(
 428                                         device->pnp.device_class,
 429                                         dev_name(&device->dev),
 430                                         event, ++button->pushed);
 431                 }
 432                 break;
 433         default:
 434                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 435                                   "Unsupported event [0x%x]\n", event));
 436                 break;
 437         }
 438 }
 439
 440 #ifdef CONFIG_PM_SLEEP
 441 static int acpi_button_suspend(struct device *dev)
 442 {
 443         struct acpi_device *device = to_acpi_device(dev);
 444         struct acpi_button *button = acpi_driver_data(device);
 445
 446         button->suspended = true;
 447         return 0;
 448 }
 449
 450 static int acpi_button_resume(struct device *dev)
 451 {
 452         struct acpi_device *device = to_acpi_device(dev);
 453         struct acpi_button *button = acpi_driver_data(device);
 454
 455         button->suspended = false;
 456         if (button->type == ACPI_BUTTON_TYPE_LID && button->input->users)
 457                 acpi_lid_initialize_state(device);
 458         return 0;
 459 }
 460 #endif
 461
 462 static int acpi_lid_input_open(struct input_dev *input)
 463 {
 464         struct acpi_device *device = input_get_drvdata(input);
 465         struct acpi_button *button = acpi_driver_data(device);
 466
 467         button->last_state = !!acpi_lid_evaluate_state(device);
 468         button->last_time = ktime_get();
 469         acpi_lid_initialize_state(device);
 470
 471         return 0;
 472 }
 473
 474 static int acpi_button_add(struct acpi_device *device)
 475 {
 476         struct acpi_button *button;
 477         struct input_dev *input;
 478         const char *hid = acpi_device_hid(device);
 479         char *name, *class;
 480         int error;
 481
 482         if (!strcmp(hid, ACPI_BUTTON_HID_LID) && dmi_check_system(lid_blacklst))
 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 result = 0;
 589
 590         if (!strncmp(val, "open", sizeof("open") - 1)) {
 591                 lid_init_state = ACPI_BUTTON_LID_INIT_OPEN;
 592                 pr_info("Notify initial lid state as open\n");
 593         } else if (!strncmp(val, "method", sizeof("method") - 1)) {
 594                 lid_init_state = ACPI_BUTTON_LID_INIT_METHOD;
 595                 pr_info("Notify initial lid state with _LID return value\n");
 596         } else if (!strncmp(val, "ignore", sizeof("ignore") - 1)) {
 597                 lid_init_state = ACPI_BUTTON_LID_INIT_IGNORE;
 598                 pr_info("Do not notify initial lid state\n");
 599         } else
 600                 result = -EINVAL;
 601         return result;
 602 }
 603
 604 static int param_get_lid_init_state(char *buffer,
 605                                     const struct kernel_param *kp)
 606 {
 607         switch (lid_init_state) {
 608         case ACPI_BUTTON_LID_INIT_OPEN:
 609                 return sprintf(buffer, "open");
 610         case ACPI_BUTTON_LID_INIT_METHOD:
 611                 return sprintf(buffer, "method");
 612         case ACPI_BUTTON_LID_INIT_IGNORE:
 613                 return sprintf(buffer, "ignore");
 614         default:
 615                 return sprintf(buffer, "invalid");
 616         }
 617         return 0;
 618 }
 619
 620 module_param_call(lid_init_state,
 621                   param_set_lid_init_state, param_get_lid_init_state,
 622                   NULL, 0644);
 623 MODULE_PARM_DESC(lid_init_state, "Behavior for reporting LID initial state");
 624
 625 static int acpi_button_register_driver(struct acpi_driver *driver)
 626 {
 627         /*
 628          * Modules such as nouveau.ko and i915.ko have a link time dependency
 629          * on acpi_lid_open(), and would therefore not be loadable on ACPI
 630          * capable kernels booted in non-ACPI mode if the return value of
 631          * acpi_bus_register_driver() is returned from here with ACPI disabled
 632          * when this driver is built as a module.
 633          */
 634         if (acpi_disabled)
 635                 return 0;
 636
 637         return acpi_bus_register_driver(driver);
 638 }
 639
 640 static void acpi_button_unregister_driver(struct acpi_driver *driver)
 641 {
 642         if (!acpi_disabled)
 643                 acpi_bus_unregister_driver(driver);
 644 }
 645
 646 module_driver(acpi_button_driver, acpi_button_register_driver,
 647                acpi_button_unregister_driver);