drivers/platform/x86/wmi.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  ACPI-WMI mapping driver
   4  *
   5  *  Copyright (C) 2007-2008 Carlos Corbacho <[email protected]>
   6  *
   7  *  GUID parsing code from ldm.c is:
   8  *   Copyright (C) 2001,2002 Richard Russon <[email protected]>
   9  *   Copyright (c) 2001-2007 Anton Altaparmakov
  10  *   Copyright (C) 2001,2002 Jakob Kemi <[email protected]>
  11  *
  12  *  WMI bus infrastructure by Andrew Lutomirski and Darren Hart:
  13  *    Copyright (C) 2015 Andrew Lutomirski
  14  *    Copyright (C) 2017 VMware, Inc. All Rights Reserved.
  15  */
  16
  17 #define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
  18
  19 #include <linux/acpi.h>
  20 #include <linux/bits.h>
  21 #include <linux/build_bug.h>
  22 #include <linux/device.h>
  23 #include <linux/init.h>
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/rwsem.h>
  28 #include <linux/slab.h>
  29 #include <linux/sysfs.h>
  30 #include <linux/types.h>
  31 #include <linux/uuid.h>
  32 #include <linux/wmi.h>
  33 #include <linux/fs.h>
  34
  35 MODULE_AUTHOR("Carlos Corbacho");
  36 MODULE_DESCRIPTION("ACPI-WMI Mapping Driver");
  37 MODULE_LICENSE("GPL");
  38
  39 struct guid_block {
  40         guid_t guid;
  41         union {
  42                 char object_id[2];
  43                 struct {
  44                         unsigned char notify_id;
  45                         unsigned char reserved;
  46                 };
  47         };
  48         u8 instance_count;
  49         u8 flags;
  50 } __packed;
  51 static_assert(sizeof(typeof_member(struct guid_block, guid)) == 16);
  52 static_assert(sizeof(struct guid_block) == 20);
  53 static_assert(__alignof__(struct guid_block) == 1);
  54
  55 enum {  /* wmi_block flags */
  56         WMI_READ_TAKES_NO_ARGS,
  57         WMI_GUID_DUPLICATED,
  58         WMI_NO_EVENT_DATA,
  59 };
  60
  61 struct wmi_block {
  62         struct wmi_device dev;
  63         struct guid_block gblock;
  64         struct acpi_device *acpi_device;
  65         struct rw_semaphore notify_lock;        /* Protects notify callback add/remove */
  66         wmi_notify_handler handler;
  67         void *handler_data;
  68         bool driver_ready;
  69         unsigned long flags;
  70 };
  71
  72 struct wmi_guid_count_context {
  73         const guid_t *guid;
  74         int count;
  75 };
  76
  77 /*
  78  * If the GUID data block is marked as expensive, we must enable and
  79  * explicitily disable data collection.
  80  */
  81 #define ACPI_WMI_EXPENSIVE   BIT(0)
  82 #define ACPI_WMI_METHOD      BIT(1)     /* GUID is a method */
  83 #define ACPI_WMI_STRING      BIT(2)     /* GUID takes & returns a string */
  84 #define ACPI_WMI_EVENT       BIT(3)     /* GUID is an event */
  85
  86 static const struct acpi_device_id wmi_device_ids[] = {
  87         {"PNP0C14", 0},
  88         {"pnp0c14", 0},
  89         { }
  90 };
  91 MODULE_DEVICE_TABLE(acpi, wmi_device_ids);
  92
  93 #define dev_to_wblock(__dev)    container_of_const(__dev, struct wmi_block, dev.dev)
  94
  95 /*
  96  * GUID parsing functions
  97  */
  98
  99 static bool guid_parse_and_compare(const char *string, const guid_t *guid)
 100 {
 101         guid_t guid_input;
 102
 103         if (guid_parse(string, &guid_input))
 104                 return false;
 105
 106         return guid_equal(&guid_input, guid);
 107 }
 108
 109 static const void *find_guid_context(struct wmi_block *wblock,
 110                                      struct wmi_driver *wdriver)
 111 {
 112         const struct wmi_device_id *id;
 113
 114         id = wdriver->id_table;
 115         if (!id)
 116                 return NULL;
 117
 118         while (*id->guid_string) {
 119                 if (guid_parse_and_compare(id->guid_string, &wblock->gblock.guid))
 120                         return id->context;
 121                 id++;
 122         }
 123         return NULL;
 124 }
 125
 126 static acpi_status wmi_method_enable(struct wmi_block *wblock, bool enable)
 127 {
 128         struct guid_block *block;
 129         char method[5];
 130         acpi_status status;
 131         acpi_handle handle;
 132
 133         block = &wblock->gblock;
 134         handle = wblock->acpi_device->handle;
 135
 136         snprintf(method, 5, "WE%02X", block->notify_id);
 137         status = acpi_execute_simple_method(handle, method, enable);
 138         if (status == AE_NOT_FOUND)
 139                 return AE_OK;
 140
 141         return status;
 142 }
 143
 144 #define WMI_ACPI_METHOD_NAME_SIZE 5
 145
 146 static inline void get_acpi_method_name(const struct wmi_block *wblock,
 147                                         const char method,
 148                                         char buffer[static WMI_ACPI_METHOD_NAME_SIZE])
 149 {
 150         static_assert(ARRAY_SIZE(wblock->gblock.object_id) == 2);
 151         static_assert(WMI_ACPI_METHOD_NAME_SIZE >= 5);
 152
 153         buffer[0] = 'W';
 154         buffer[1] = method;
 155         buffer[2] = wblock->gblock.object_id[0];
 156         buffer[3] = wblock->gblock.object_id[1];
 157         buffer[4] = '\0';
 158 }
 159
 160 static inline acpi_object_type get_param_acpi_type(const struct wmi_block *wblock)
 161 {
 162         if (wblock->gblock.flags & ACPI_WMI_STRING)
 163                 return ACPI_TYPE_STRING;
 164         else
 165                 return ACPI_TYPE_BUFFER;
 166 }
 167
 168 static int wmidev_match_guid(struct device *dev, const void *data)
 169 {
 170         struct wmi_block *wblock = dev_to_wblock(dev);
 171         const guid_t *guid = data;
 172
 173         /* Legacy GUID-based functions are restricted to only see
 174          * a single WMI device for each GUID.
 175          */
 176         if (test_bit(WMI_GUID_DUPLICATED, &wblock->flags))
 177                 return 0;
 178
 179         if (guid_equal(guid, &wblock->gblock.guid))
 180                 return 1;
 181
 182         return 0;
 183 }
 184
 185 static const struct bus_type wmi_bus_type;
 186
 187 static struct wmi_device *wmi_find_device_by_guid(const char *guid_string)
 188 {
 189         struct device *dev;
 190         guid_t guid;
 191         int ret;
 192
 193         ret = guid_parse(guid_string, &guid);
 194         if (ret < 0)
 195                 return ERR_PTR(ret);
 196
 197         dev = bus_find_device(&wmi_bus_type, NULL, &guid, wmidev_match_guid);
 198         if (!dev)
 199                 return ERR_PTR(-ENODEV);
 200
 201         return to_wmi_device(dev);
 202 }
 203
 204 static void wmi_device_put(struct wmi_device *wdev)
 205 {
 206         put_device(&wdev->dev);
 207 }
 208
 209 /*
 210  * Exported WMI functions
 211  */
 212
 213 /**
 214  * wmi_instance_count - Get number of WMI object instances
 215  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 216  *
 217  * Get the number of WMI object instances.
 218  *
 219  * Returns: Number of WMI object instances or negative error code.
 220  */
 221 int wmi_instance_count(const char *guid_string)
 222 {
 223         struct wmi_device *wdev;
 224         int ret;
 225
 226         wdev = wmi_find_device_by_guid(guid_string);
 227         if (IS_ERR(wdev))
 228                 return PTR_ERR(wdev);
 229
 230         ret = wmidev_instance_count(wdev);
 231         wmi_device_put(wdev);
 232
 233         return ret;
 234 }
 235 EXPORT_SYMBOL_GPL(wmi_instance_count);
 236
 237 /**
 238  * wmidev_instance_count - Get number of WMI object instances
 239  * @wdev: A wmi bus device from a driver
 240  *
 241  * Get the number of WMI object instances.
 242  *
 243  * Returns: Number of WMI object instances.
 244  */
 245 u8 wmidev_instance_count(struct wmi_device *wdev)
 246 {
 247         struct wmi_block *wblock = container_of(wdev, struct wmi_block, dev);
 248
 249         return wblock->gblock.instance_count;
 250 }
 251 EXPORT_SYMBOL_GPL(wmidev_instance_count);
 252
 253 /**
 254  * wmi_evaluate_method - Evaluate a WMI method (deprecated)
 255  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 256  * @instance: Instance index
 257  * @method_id: Method ID to call
 258  * @in: Mandatory buffer containing input for the method call
 259  * @out: Empty buffer to return the method results
 260  *
 261  * Call an ACPI-WMI method, the caller must free @out.
 262  *
 263  * Return: acpi_status signaling success or error.
 264  */
 265 acpi_status wmi_evaluate_method(const char *guid_string, u8 instance, u32 method_id,
 266                                 const struct acpi_buffer *in, struct acpi_buffer *out)
 267 {
 268         struct wmi_device *wdev;
 269         acpi_status status;
 270
 271         wdev = wmi_find_device_by_guid(guid_string);
 272         if (IS_ERR(wdev))
 273                 return AE_ERROR;
 274
 275         status = wmidev_evaluate_method(wdev, instance, method_id, in, out);
 276
 277         wmi_device_put(wdev);
 278
 279         return status;
 280 }
 281 EXPORT_SYMBOL_GPL(wmi_evaluate_method);
 282
 283 /**
 284  * wmidev_evaluate_method - Evaluate a WMI method
 285  * @wdev: A wmi bus device from a driver
 286  * @instance: Instance index
 287  * @method_id: Method ID to call
 288  * @in: Mandatory buffer containing input for the method call
 289  * @out: Empty buffer to return the method results
 290  *
 291  * Call an ACPI-WMI method, the caller must free @out.
 292  *
 293  * Return: acpi_status signaling success or error.
 294  */
 295 acpi_status wmidev_evaluate_method(struct wmi_device *wdev, u8 instance, u32 method_id,
 296                                    const struct acpi_buffer *in, struct acpi_buffer *out)
 297 {
 298         struct guid_block *block;
 299         struct wmi_block *wblock;
 300         acpi_handle handle;
 301         struct acpi_object_list input;
 302         union acpi_object params[3];
 303         char method[WMI_ACPI_METHOD_NAME_SIZE];
 304
 305         wblock = container_of(wdev, struct wmi_block, dev);
 306         block = &wblock->gblock;
 307         handle = wblock->acpi_device->handle;
 308
 309         if (!in)
 310                 return AE_BAD_DATA;
 311
 312         if (!(block->flags & ACPI_WMI_METHOD))
 313                 return AE_BAD_DATA;
 314
 315         if (block->instance_count <= instance)
 316                 return AE_BAD_PARAMETER;
 317
 318         input.count = 3;
 319         input.pointer = params;
 320
 321         params[0].type = ACPI_TYPE_INTEGER;
 322         params[0].integer.value = instance;
 323         params[1].type = ACPI_TYPE_INTEGER;
 324         params[1].integer.value = method_id;
 325         params[2].type = get_param_acpi_type(wblock);
 326         params[2].buffer.length = in->length;
 327         params[2].buffer.pointer = in->pointer;
 328
 329         get_acpi_method_name(wblock, 'M', method);
 330
 331         return acpi_evaluate_object(handle, method, &input, out);
 332 }
 333 EXPORT_SYMBOL_GPL(wmidev_evaluate_method);
 334
 335 static acpi_status __query_block(struct wmi_block *wblock, u8 instance,
 336                                  struct acpi_buffer *out)
 337 {
 338         struct guid_block *block;
 339         acpi_handle handle;
 340         acpi_status status, wc_status = AE_ERROR;
 341         struct acpi_object_list input;
 342         union acpi_object wq_params[1];
 343         char wc_method[WMI_ACPI_METHOD_NAME_SIZE];
 344         char method[WMI_ACPI_METHOD_NAME_SIZE];
 345
 346         if (!out)
 347                 return AE_BAD_PARAMETER;
 348
 349         block = &wblock->gblock;
 350         handle = wblock->acpi_device->handle;
 351
 352         if (block->instance_count <= instance)
 353                 return AE_BAD_PARAMETER;
 354
 355         /* Check GUID is a data block */
 356         if (block->flags & (ACPI_WMI_EVENT | ACPI_WMI_METHOD))
 357                 return AE_ERROR;
 358
 359         input.count = 1;
 360         input.pointer = wq_params;
 361         wq_params[0].type = ACPI_TYPE_INTEGER;
 362         wq_params[0].integer.value = instance;
 363
 364         if (instance == 0 && test_bit(WMI_READ_TAKES_NO_ARGS, &wblock->flags))
 365                 input.count = 0;
 366
 367         /*
 368          * If ACPI_WMI_EXPENSIVE, call the relevant WCxx method first to
 369          * enable collection.
 370          */
 371         if (block->flags & ACPI_WMI_EXPENSIVE) {
 372                 get_acpi_method_name(wblock, 'C', wc_method);
 373
 374                 /*
 375                  * Some GUIDs break the specification by declaring themselves
 376                  * expensive, but have no corresponding WCxx method. So we
 377                  * should not fail if this happens.
 378                  */
 379                 wc_status = acpi_execute_simple_method(handle, wc_method, 1);
 380         }
 381
 382         get_acpi_method_name(wblock, 'Q', method);
 383         status = acpi_evaluate_object(handle, method, &input, out);
 384
 385         /*
 386          * If ACPI_WMI_EXPENSIVE, call the relevant WCxx method, even if
 387          * the WQxx method failed - we should disable collection anyway.
 388          */
 389         if ((block->flags & ACPI_WMI_EXPENSIVE) && ACPI_SUCCESS(wc_status)) {
 390                 /*
 391                  * Ignore whether this WCxx call succeeds or not since
 392                  * the previously executed WQxx method call might have
 393                  * succeeded, and returning the failing status code
 394                  * of this call would throw away the result of the WQxx
 395                  * call, potentially leaking memory.
 396                  */
 397                 acpi_execute_simple_method(handle, wc_method, 0);
 398         }
 399
 400         return status;
 401 }
 402
 403 /**
 404  * wmi_query_block - Return contents of a WMI block (deprecated)
 405  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 406  * @instance: Instance index
 407  * @out: Empty buffer to return the contents of the data block to
 408  *
 409  * Query a ACPI-WMI block, the caller must free @out.
 410  *
 411  * Return: ACPI object containing the content of the WMI block.
 412  */
 413 acpi_status wmi_query_block(const char *guid_string, u8 instance,
 414                             struct acpi_buffer *out)
 415 {
 416         struct wmi_block *wblock;
 417         struct wmi_device *wdev;
 418         acpi_status status;
 419
 420         wdev = wmi_find_device_by_guid(guid_string);
 421         if (IS_ERR(wdev))
 422                 return AE_ERROR;
 423
 424         wblock = container_of(wdev, struct wmi_block, dev);
 425         status = __query_block(wblock, instance, out);
 426
 427         wmi_device_put(wdev);
 428
 429         return status;
 430 }
 431 EXPORT_SYMBOL_GPL(wmi_query_block);
 432
 433 /**
 434  * wmidev_block_query - Return contents of a WMI block
 435  * @wdev: A wmi bus device from a driver
 436  * @instance: Instance index
 437  *
 438  * Query an ACPI-WMI block, the caller must free the result.
 439  *
 440  * Return: ACPI object containing the content of the WMI block.
 441  */
 442 union acpi_object *wmidev_block_query(struct wmi_device *wdev, u8 instance)
 443 {
 444         struct acpi_buffer out = { ACPI_ALLOCATE_BUFFER, NULL };
 445         struct wmi_block *wblock = container_of(wdev, struct wmi_block, dev);
 446
 447         if (ACPI_FAILURE(__query_block(wblock, instance, &out)))
 448                 return NULL;
 449
 450         return out.pointer;
 451 }
 452 EXPORT_SYMBOL_GPL(wmidev_block_query);
 453
 454 /**
 455  * wmi_set_block - Write to a WMI block (deprecated)
 456  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 457  * @instance: Instance index
 458  * @in: Buffer containing new values for the data block
 459  *
 460  * Write the contents of the input buffer to an ACPI-WMI data block.
 461  *
 462  * Return: acpi_status signaling success or error.
 463  */
 464 acpi_status wmi_set_block(const char *guid_string, u8 instance, const struct acpi_buffer *in)
 465 {
 466         struct wmi_device *wdev;
 467         acpi_status status;
 468
 469         wdev = wmi_find_device_by_guid(guid_string);
 470         if (IS_ERR(wdev))
 471                 return AE_ERROR;
 472
 473         status =  wmidev_block_set(wdev, instance, in);
 474         wmi_device_put(wdev);
 475
 476         return status;
 477 }
 478 EXPORT_SYMBOL_GPL(wmi_set_block);
 479
 480 /**
 481  * wmidev_block_set - Write to a WMI block
 482  * @wdev: A wmi bus device from a driver
 483  * @instance: Instance index
 484  * @in: Buffer containing new values for the data block
 485  *
 486  * Write contents of the input buffer to an ACPI-WMI data block.
 487  *
 488  * Return: acpi_status signaling success or error.
 489  */
 490 acpi_status wmidev_block_set(struct wmi_device *wdev, u8 instance, const struct acpi_buffer *in)
 491 {
 492         struct wmi_block *wblock = container_of(wdev, struct wmi_block, dev);
 493         acpi_handle handle = wblock->acpi_device->handle;
 494         struct guid_block *block = &wblock->gblock;
 495         char method[WMI_ACPI_METHOD_NAME_SIZE];
 496         struct acpi_object_list input;
 497         union acpi_object params[2];
 498
 499         if (!in)
 500                 return AE_BAD_DATA;
 501
 502         if (block->instance_count <= instance)
 503                 return AE_BAD_PARAMETER;
 504
 505         /* Check GUID is a data block */
 506         if (block->flags & (ACPI_WMI_EVENT | ACPI_WMI_METHOD))
 507                 return AE_ERROR;
 508
 509         input.count = 2;
 510         input.pointer = params;
 511         params[0].type = ACPI_TYPE_INTEGER;
 512         params[0].integer.value = instance;
 513         params[1].type = get_param_acpi_type(wblock);
 514         params[1].buffer.length = in->length;
 515         params[1].buffer.pointer = in->pointer;
 516
 517         get_acpi_method_name(wblock, 'S', method);
 518
 519         return acpi_evaluate_object(handle, method, &input, NULL);
 520 }
 521 EXPORT_SYMBOL_GPL(wmidev_block_set);
 522
 523 /**
 524  * wmi_install_notify_handler - Register handler for WMI events (deprecated)
 525  * @guid: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 526  * @handler: Function to handle notifications
 527  * @data: Data to be returned to handler when event is fired
 528  *
 529  * Register a handler for events sent to the ACPI-WMI mapper device.
 530  *
 531  * Return: acpi_status signaling success or error.
 532  */
 533 acpi_status wmi_install_notify_handler(const char *guid,
 534                                        wmi_notify_handler handler,
 535                                        void *data)
 536 {
 537         struct wmi_block *wblock;
 538         struct wmi_device *wdev;
 539         acpi_status status;
 540
 541         wdev = wmi_find_device_by_guid(guid);
 542         if (IS_ERR(wdev))
 543                 return AE_ERROR;
 544
 545         wblock = container_of(wdev, struct wmi_block, dev);
 546
 547         down_write(&wblock->notify_lock);
 548         if (wblock->handler) {
 549                 status = AE_ALREADY_ACQUIRED;
 550         } else {
 551                 wblock->handler = handler;
 552                 wblock->handler_data = data;
 553
 554                 if (ACPI_FAILURE(wmi_method_enable(wblock, true)))
 555                         dev_warn(&wblock->dev.dev, "Failed to enable device\n");
 556
 557                 status = AE_OK;
 558         }
 559         up_write(&wblock->notify_lock);
 560
 561         wmi_device_put(wdev);
 562
 563         return status;
 564 }
 565 EXPORT_SYMBOL_GPL(wmi_install_notify_handler);
 566
 567 /**
 568  * wmi_remove_notify_handler - Unregister handler for WMI events (deprecated)
 569  * @guid: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 570  *
 571  * Unregister handler for events sent to the ACPI-WMI mapper device.
 572  *
 573  * Return: acpi_status signaling success or error.
 574  */
 575 acpi_status wmi_remove_notify_handler(const char *guid)
 576 {
 577         struct wmi_block *wblock;
 578         struct wmi_device *wdev;
 579         acpi_status status;
 580
 581         wdev = wmi_find_device_by_guid(guid);
 582         if (IS_ERR(wdev))
 583                 return AE_ERROR;
 584
 585         wblock = container_of(wdev, struct wmi_block, dev);
 586
 587         down_write(&wblock->notify_lock);
 588         if (!wblock->handler) {
 589                 status = AE_NULL_ENTRY;
 590         } else {
 591                 if (ACPI_FAILURE(wmi_method_enable(wblock, false)))
 592                         dev_warn(&wblock->dev.dev, "Failed to disable device\n");
 593
 594                 wblock->handler = NULL;
 595                 wblock->handler_data = NULL;
 596
 597                 status = AE_OK;
 598         }
 599         up_write(&wblock->notify_lock);
 600
 601         wmi_device_put(wdev);
 602
 603         return status;
 604 }
 605 EXPORT_SYMBOL_GPL(wmi_remove_notify_handler);
 606
 607 /**
 608  * wmi_has_guid - Check if a GUID is available
 609  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 610  *
 611  * Check if a given GUID is defined by _WDG.
 612  *
 613  * Return: True if GUID is available, false otherwise.
 614  */
 615 bool wmi_has_guid(const char *guid_string)
 616 {
 617         struct wmi_device *wdev;
 618
 619         wdev = wmi_find_device_by_guid(guid_string);
 620         if (IS_ERR(wdev))
 621                 return false;
 622
 623         wmi_device_put(wdev);
 624
 625         return true;
 626 }
 627 EXPORT_SYMBOL_GPL(wmi_has_guid);
 628
 629 /**
 630  * wmi_get_acpi_device_uid() - Get _UID name of ACPI device that defines GUID (deprecated)
 631  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 632  *
 633  * Find the _UID of ACPI device associated with this WMI GUID.
 634  *
 635  * Return: The ACPI _UID field value or NULL if the WMI GUID was not found.
 636  */
 637 char *wmi_get_acpi_device_uid(const char *guid_string)
 638 {
 639         struct wmi_block *wblock;
 640         struct wmi_device *wdev;
 641         char *uid;
 642
 643         wdev = wmi_find_device_by_guid(guid_string);
 644         if (IS_ERR(wdev))
 645                 return NULL;
 646
 647         wblock = container_of(wdev, struct wmi_block, dev);
 648         uid = acpi_device_uid(wblock->acpi_device);
 649
 650         wmi_device_put(wdev);
 651
 652         return uid;
 653 }
 654 EXPORT_SYMBOL_GPL(wmi_get_acpi_device_uid);
 655
 656 /*
 657  * sysfs interface
 658  */
 659 static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 660                              char *buf)
 661 {
 662         struct wmi_block *wblock = dev_to_wblock(dev);
 663
 664         return sysfs_emit(buf, "wmi:%pUL\n", &wblock->gblock.guid);
 665 }
 666 static DEVICE_ATTR_RO(modalias);
 667
 668 static ssize_t guid_show(struct device *dev, struct device_attribute *attr,
 669                          char *buf)
 670 {
 671         struct wmi_block *wblock = dev_to_wblock(dev);
 672
 673         return sysfs_emit(buf, "%pUL\n", &wblock->gblock.guid);
 674 }
 675 static DEVICE_ATTR_RO(guid);
 676
 677 static ssize_t instance_count_show(struct device *dev,
 678                                    struct device_attribute *attr, char *buf)
 679 {
 680         struct wmi_block *wblock = dev_to_wblock(dev);
 681
 682         return sysfs_emit(buf, "%d\n", (int)wblock->gblock.instance_count);
 683 }
 684 static DEVICE_ATTR_RO(instance_count);
 685
 686 static ssize_t expensive_show(struct device *dev,
 687                               struct device_attribute *attr, char *buf)
 688 {
 689         struct wmi_block *wblock = dev_to_wblock(dev);
 690
 691         return sysfs_emit(buf, "%d\n",
 692                           (wblock->gblock.flags & ACPI_WMI_EXPENSIVE) != 0);
 693 }
 694 static DEVICE_ATTR_RO(expensive);
 695
 696 static ssize_t driver_override_show(struct device *dev, struct device_attribute *attr,
 697                                     char *buf)
 698 {
 699         struct wmi_device *wdev = to_wmi_device(dev);
 700         ssize_t ret;
 701
 702         device_lock(dev);
 703         ret = sysfs_emit(buf, "%s\n", wdev->driver_override);
 704         device_unlock(dev);
 705
 706         return ret;
 707 }
 708
 709 static ssize_t driver_override_store(struct device *dev, struct device_attribute *attr,
 710                                      const char *buf, size_t count)
 711 {
 712         struct wmi_device *wdev = to_wmi_device(dev);
 713         int ret;
 714
 715         ret = driver_set_override(dev, &wdev->driver_override, buf, count);
 716         if (ret < 0)
 717                 return ret;
 718
 719         return count;
 720 }
 721 static DEVICE_ATTR_RW(driver_override);
 722
 723 static struct attribute *wmi_attrs[] = {
 724         &dev_attr_modalias.attr,
 725         &dev_attr_guid.attr,
 726         &dev_attr_instance_count.attr,
 727         &dev_attr_expensive.attr,
 728         &dev_attr_driver_override.attr,
 729         NULL
 730 };
 731 ATTRIBUTE_GROUPS(wmi);
 732
 733 static ssize_t notify_id_show(struct device *dev, struct device_attribute *attr,
 734                               char *buf)
 735 {
 736         struct wmi_block *wblock = dev_to_wblock(dev);
 737
 738         return sysfs_emit(buf, "%02X\n", (unsigned int)wblock->gblock.notify_id);
 739 }
 740 static DEVICE_ATTR_RO(notify_id);
 741
 742 static struct attribute *wmi_event_attrs[] = {
 743         &dev_attr_notify_id.attr,
 744         NULL
 745 };
 746 ATTRIBUTE_GROUPS(wmi_event);
 747
 748 static ssize_t object_id_show(struct device *dev, struct device_attribute *attr,
 749                               char *buf)
 750 {
 751         struct wmi_block *wblock = dev_to_wblock(dev);
 752
 753         return sysfs_emit(buf, "%c%c\n", wblock->gblock.object_id[0],
 754                           wblock->gblock.object_id[1]);
 755 }
 756 static DEVICE_ATTR_RO(object_id);
 757
 758 static ssize_t setable_show(struct device *dev, struct device_attribute *attr,
 759                             char *buf)
 760 {
 761         struct wmi_device *wdev = to_wmi_device(dev);
 762
 763         return sysfs_emit(buf, "%d\n", (int)wdev->setable);
 764 }
 765 static DEVICE_ATTR_RO(setable);
 766
 767 static struct attribute *wmi_data_attrs[] = {
 768         &dev_attr_object_id.attr,
 769         &dev_attr_setable.attr,
 770         NULL
 771 };
 772 ATTRIBUTE_GROUPS(wmi_data);
 773
 774 static struct attribute *wmi_method_attrs[] = {
 775         &dev_attr_object_id.attr,
 776         NULL
 777 };
 778 ATTRIBUTE_GROUPS(wmi_method);
 779
 780 static int wmi_dev_uevent(const struct device *dev, struct kobj_uevent_env *env)
 781 {
 782         const struct wmi_block *wblock = dev_to_wblock(dev);
 783
 784         if (add_uevent_var(env, "MODALIAS=wmi:%pUL", &wblock->gblock.guid))
 785                 return -ENOMEM;
 786
 787         if (add_uevent_var(env, "WMI_GUID=%pUL", &wblock->gblock.guid))
 788                 return -ENOMEM;
 789
 790         return 0;
 791 }
 792
 793 static void wmi_dev_release(struct device *dev)
 794 {
 795         struct wmi_block *wblock = dev_to_wblock(dev);
 796
 797         kfree(wblock->dev.driver_override);
 798         kfree(wblock);
 799 }
 800
 801 static int wmi_dev_match(struct device *dev, const struct device_driver *driver)
 802 {
 803         const struct wmi_driver *wmi_driver = to_wmi_driver(driver);
 804         struct wmi_block *wblock = dev_to_wblock(dev);
 805         const struct wmi_device_id *id = wmi_driver->id_table;
 806
 807         /* When driver_override is set, only bind to the matching driver */
 808         if (wblock->dev.driver_override)
 809                 return !strcmp(wblock->dev.driver_override, driver->name);
 810
 811         if (id == NULL)
 812                 return 0;
 813
 814         while (*id->guid_string) {
 815                 if (guid_parse_and_compare(id->guid_string, &wblock->gblock.guid))
 816                         return 1;
 817
 818                 id++;
 819         }
 820
 821         return 0;
 822 }
 823
 824 static int wmi_dev_probe(struct device *dev)
 825 {
 826         struct wmi_block *wblock = dev_to_wblock(dev);
 827         struct wmi_driver *wdriver = to_wmi_driver(dev->driver);
 828         int ret = 0;
 829
 830         /* Some older WMI drivers will break if instantiated multiple times,
 831          * so they are blocked from probing WMI devices with a duplicated GUID.
 832          *
 833          * New WMI drivers should support being instantiated multiple times.
 834          */
 835         if (test_bit(WMI_GUID_DUPLICATED, &wblock->flags) && !wdriver->no_singleton) {
 836                 dev_warn(dev, "Legacy driver %s cannot be instantiated multiple times\n",
 837                          dev->driver->name);
 838
 839                 return -ENODEV;
 840         }
 841
 842         if (wdriver->notify) {
 843                 if (test_bit(WMI_NO_EVENT_DATA, &wblock->flags) && !wdriver->no_notify_data)
 844                         return -ENODEV;
 845         }
 846
 847         if (ACPI_FAILURE(wmi_method_enable(wblock, true)))
 848                 dev_warn(dev, "failed to enable device -- probing anyway\n");
 849
 850         if (wdriver->probe) {
 851                 ret = wdriver->probe(to_wmi_device(dev),
 852                                 find_guid_context(wblock, wdriver));
 853                 if (ret) {
 854                         if (ACPI_FAILURE(wmi_method_enable(wblock, false)))
 855                                 dev_warn(dev, "Failed to disable device\n");
 856
 857                         return ret;
 858                 }
 859         }
 860
 861         down_write(&wblock->notify_lock);
 862         wblock->driver_ready = true;
 863         up_write(&wblock->notify_lock);
 864
 865         return 0;
 866 }
 867
 868 static void wmi_dev_remove(struct device *dev)
 869 {
 870         struct wmi_block *wblock = dev_to_wblock(dev);
 871         struct wmi_driver *wdriver = to_wmi_driver(dev->driver);
 872
 873         down_write(&wblock->notify_lock);
 874         wblock->driver_ready = false;
 875         up_write(&wblock->notify_lock);
 876
 877         if (wdriver->remove)
 878                 wdriver->remove(to_wmi_device(dev));
 879
 880         if (ACPI_FAILURE(wmi_method_enable(wblock, false)))
 881                 dev_warn(dev, "failed to disable device\n");
 882 }
 883
 884 static void wmi_dev_shutdown(struct device *dev)
 885 {
 886         struct wmi_driver *wdriver;
 887         struct wmi_block *wblock;
 888
 889         if (dev->driver) {
 890                 wdriver = to_wmi_driver(dev->driver);
 891                 wblock = dev_to_wblock(dev);
 892
 893                 /*
 894                  * Some machines return bogus WMI event data when disabling
 895                  * the WMI event. Because of this we must prevent the associated
 896                  * WMI driver from receiving new WMI events before disabling it.
 897                  */
 898                 down_write(&wblock->notify_lock);
 899                 wblock->driver_ready = false;
 900                 up_write(&wblock->notify_lock);
 901
 902                 if (wdriver->shutdown)
 903                         wdriver->shutdown(to_wmi_device(dev));
 904
 905                 if (ACPI_FAILURE(wmi_method_enable(wblock, false)))
 906                         dev_warn(dev, "Failed to disable device\n");
 907         }
 908 }
 909
 910 static struct class wmi_bus_class = {
 911         .name = "wmi_bus",
 912 };
 913
 914 static const struct bus_type wmi_bus_type = {
 915         .name = "wmi",
 916         .dev_groups = wmi_groups,
 917         .match = wmi_dev_match,
 918         .uevent = wmi_dev_uevent,
 919         .probe = wmi_dev_probe,
 920         .remove = wmi_dev_remove,
 921         .shutdown = wmi_dev_shutdown,
 922 };
 923
 924 static const struct device_type wmi_type_event = {
 925         .name = "event",
 926         .groups = wmi_event_groups,
 927         .release = wmi_dev_release,
 928 };
 929
 930 static const struct device_type wmi_type_method = {
 931         .name = "method",
 932         .groups = wmi_method_groups,
 933         .release = wmi_dev_release,
 934 };
 935
 936 static const struct device_type wmi_type_data = {
 937         .name = "data",
 938         .groups = wmi_data_groups,
 939         .release = wmi_dev_release,
 940 };
 941
 942 static int wmi_count_guids(struct device *dev, void *data)
 943 {
 944         struct wmi_guid_count_context *context = data;
 945         struct wmi_block *wblock = dev_to_wblock(dev);
 946
 947         if (guid_equal(&wblock->gblock.guid, context->guid))
 948                 context->count++;
 949
 950         return 0;
 951 }
 952
 953 static int guid_count(const guid_t *guid)
 954 {
 955         struct wmi_guid_count_context context = {
 956                 .guid = guid,
 957                 .count = 0,
 958         };
 959         int ret;
 960
 961         ret = bus_for_each_dev(&wmi_bus_type, NULL, &context, wmi_count_guids);
 962         if (ret < 0)
 963                 return ret;
 964
 965         return context.count;
 966 }
 967
 968 static int wmi_create_device(struct device *wmi_bus_dev,
 969                              struct wmi_block *wblock,
 970                              struct acpi_device *device)
 971 {
 972         char method[WMI_ACPI_METHOD_NAME_SIZE];
 973         struct acpi_device_info *info;
 974         acpi_handle method_handle;
 975         acpi_status status;
 976         int count;
 977
 978         if (wblock->gblock.flags & ACPI_WMI_EVENT) {
 979                 wblock->dev.dev.type = &wmi_type_event;
 980                 goto out_init;
 981         }
 982
 983         if (wblock->gblock.flags & ACPI_WMI_METHOD) {
 984                 get_acpi_method_name(wblock, 'M', method);
 985                 if (!acpi_has_method(device->handle, method)) {
 986                         dev_warn(wmi_bus_dev,
 987                                  FW_BUG "%s method block execution control method not found\n",
 988                                  method);
 989
 990                         return -ENXIO;
 991                 }
 992
 993                 wblock->dev.dev.type = &wmi_type_method;
 994                 goto out_init;
 995         }
 996
 997         /*
 998          * Data Block Query Control Method (WQxx by convention) is
 999          * required per the WMI documentation. If it is not present,
1000          * we ignore this data block.
1001          */
1002         get_acpi_method_name(wblock, 'Q', method);
1003         status = acpi_get_handle(device->handle, method, &method_handle);
1004         if (ACPI_FAILURE(status)) {
1005                 dev_warn(wmi_bus_dev,
1006                          FW_BUG "%s data block query control method not found\n",
1007                          method);
1008
1009                 return -ENXIO;
1010         }
1011
1012         status = acpi_get_object_info(method_handle, &info);
1013         if (ACPI_FAILURE(status))
1014                 return -EIO;
1015
1016         wblock->dev.dev.type = &wmi_type_data;
1017
1018         /*
1019          * The Microsoft documentation specifically states:
1020          *
1021          *   Data blocks registered with only a single instance
1022          *   can ignore the parameter.
1023          *
1024          * ACPICA will get mad at us if we call the method with the wrong number
1025          * of arguments, so check what our method expects.  (On some Dell
1026          * laptops, WQxx may not be a method at all.)
1027          */
1028         if (info->type != ACPI_TYPE_METHOD || info->param_count == 0)
1029                 set_bit(WMI_READ_TAKES_NO_ARGS, &wblock->flags);
1030
1031         kfree(info);
1032
1033         get_acpi_method_name(wblock, 'S', method);
1034         if (acpi_has_method(device->handle, method))
1035                 wblock->dev.setable = true;
1036
1037  out_init:
1038         init_rwsem(&wblock->notify_lock);
1039         wblock->driver_ready = false;
1040         wblock->dev.dev.bus = &wmi_bus_type;
1041         wblock->dev.dev.parent = wmi_bus_dev;
1042
1043         count = guid_count(&wblock->gblock.guid);
1044         if (count < 0)
1045                 return count;
1046
1047         if (count) {
1048                 dev_set_name(&wblock->dev.dev, "%pUL-%d", &wblock->gblock.guid, count);
1049                 set_bit(WMI_GUID_DUPLICATED, &wblock->flags);
1050         } else {
1051                 dev_set_name(&wblock->dev.dev, "%pUL", &wblock->gblock.guid);
1052         }
1053
1054         device_initialize(&wblock->dev.dev);
1055
1056         return 0;
1057 }
1058
1059 static int wmi_add_device(struct platform_device *pdev, struct wmi_device *wdev)
1060 {
1061         struct device_link *link;
1062
1063         /*
1064          * Many aggregate WMI drivers do not use -EPROBE_DEFER when they
1065          * are unable to find a WMI device during probe, instead they require
1066          * all WMI devices associated with an platform device to become available
1067          * at once. This device link thus prevents WMI drivers from probing until
1068          * the associated platform device has finished probing (and has registered
1069          * all discovered WMI devices).
1070          */
1071
1072         link = device_link_add(&wdev->dev, &pdev->dev, DL_FLAG_AUTOREMOVE_SUPPLIER);
1073         if (!link)
1074                 return -EINVAL;
1075
1076         return device_add(&wdev->dev);
1077 }
1078
1079 /*
1080  * Parse the _WDG method for the GUID data blocks
1081  */
1082 static int parse_wdg(struct device *wmi_bus_dev, struct platform_device *pdev)
1083 {
1084         struct acpi_device *device = ACPI_COMPANION(&pdev->dev);
1085         struct acpi_buffer out = {ACPI_ALLOCATE_BUFFER, NULL};
1086         const struct guid_block *gblock;
1087         bool event_data_available;
1088         struct wmi_block *wblock;
1089         union acpi_object *obj;
1090         acpi_status status;
1091         u32 i, total;
1092         int retval;
1093
1094         status = acpi_evaluate_object(device->handle, "_WDG", NULL, &out);
1095         if (ACPI_FAILURE(status))
1096                 return -ENXIO;
1097
1098         obj = out.pointer;
1099         if (!obj)
1100                 return -ENXIO;
1101
1102         if (obj->type != ACPI_TYPE_BUFFER) {
1103                 kfree(obj);
1104                 return -ENXIO;
1105         }
1106
1107         event_data_available = acpi_has_method(device->handle, "_WED");
1108         gblock = (const struct guid_block *)obj->buffer.pointer;
1109         total = obj->buffer.length / sizeof(struct guid_block);
1110
1111         for (i = 0; i < total; i++) {
1112                 if (!gblock[i].instance_count) {
1113                         dev_info(wmi_bus_dev, FW_INFO "%pUL has zero instances\n", &gblock[i].guid);
1114                         continue;
1115                 }
1116
1117                 wblock = kzalloc(sizeof(*wblock), GFP_KERNEL);
1118                 if (!wblock)
1119                         continue;
1120
1121                 wblock->acpi_device = device;
1122                 wblock->gblock = gblock[i];
1123                 if (gblock[i].flags & ACPI_WMI_EVENT && !event_data_available)
1124                         set_bit(WMI_NO_EVENT_DATA, &wblock->flags);
1125
1126                 retval = wmi_create_device(wmi_bus_dev, wblock, device);
1127                 if (retval) {
1128                         kfree(wblock);
1129                         continue;
1130                 }
1131
1132                 retval = wmi_add_device(pdev, &wblock->dev);
1133                 if (retval) {
1134                         dev_err(wmi_bus_dev, "failed to register %pUL\n",
1135                                 &wblock->gblock.guid);
1136
1137                         put_device(&wblock->dev.dev);
1138                 }
1139         }
1140
1141         kfree(obj);
1142
1143         return 0;
1144 }
1145
1146 static int wmi_get_notify_data(struct wmi_block *wblock, union acpi_object **obj)
1147 {
1148         struct acpi_buffer data = { ACPI_ALLOCATE_BUFFER, NULL };
1149         union acpi_object param = {
1150                 .integer = {
1151                         .type = ACPI_TYPE_INTEGER,
1152                         .value = wblock->gblock.notify_id,
1153                 }
1154         };
1155         struct acpi_object_list input = {
1156                 .count = 1,
1157                 .pointer = &param,
1158         };
1159         acpi_status status;
1160
1161         status = acpi_evaluate_object(wblock->acpi_device->handle, "_WED", &input, &data);
1162         if (ACPI_FAILURE(status)) {
1163                 dev_warn(&wblock->dev.dev, "Failed to get event data\n");
1164                 return -EIO;
1165         }
1166
1167         *obj = data.pointer;
1168
1169         return 0;
1170 }
1171
1172 static void wmi_notify_driver(struct wmi_block *wblock, union acpi_object *obj)
1173 {
1174         struct wmi_driver *driver = to_wmi_driver(wblock->dev.dev.driver);
1175
1176         if (!obj && !driver->no_notify_data) {
1177                 dev_warn(&wblock->dev.dev, "Event contains no event data\n");
1178                 return;
1179         }
1180
1181         if (driver->notify)
1182                 driver->notify(&wblock->dev, obj);
1183 }
1184
1185 static int wmi_notify_device(struct device *dev, void *data)
1186 {
1187         struct wmi_block *wblock = dev_to_wblock(dev);
1188         union acpi_object *obj = NULL;
1189         u32 *event = data;
1190         int ret;
1191
1192         if (!(wblock->gblock.flags & ACPI_WMI_EVENT && wblock->gblock.notify_id == *event))
1193                 return 0;
1194
1195         /* The ACPI WMI specification says that _WED should be
1196          * evaluated every time an notification is received, even
1197          * if no consumers are present.
1198          *
1199          * Some firmware implementations actually depend on this
1200          * by using a queue for events which will fill up if the
1201          * WMI driver core stops evaluating _WED due to missing
1202          * WMI event consumers.
1203          */
1204         if (!test_bit(WMI_NO_EVENT_DATA, &wblock->flags)) {
1205                 ret = wmi_get_notify_data(wblock, &obj);
1206                 if (ret < 0)
1207                         return -EIO;
1208         }
1209
1210         down_read(&wblock->notify_lock);
1211
1212         if (wblock->dev.dev.driver && wblock->driver_ready)
1213                 wmi_notify_driver(wblock, obj);
1214
1215         if (wblock->handler)
1216                 wblock->handler(obj, wblock->handler_data);
1217
1218         up_read(&wblock->notify_lock);
1219
1220         kfree(obj);
1221
1222         acpi_bus_generate_netlink_event("wmi", acpi_dev_name(wblock->acpi_device), *event, 0);
1223
1224         return -EBUSY;
1225 }
1226
1227 static void acpi_wmi_notify_handler(acpi_handle handle, u32 event, void *context)
1228 {
1229         struct device *wmi_bus_dev = context;
1230
1231         device_for_each_child(wmi_bus_dev, &event, wmi_notify_device);
1232 }
1233
1234 static int wmi_remove_device(struct device *dev, void *data)
1235 {
1236         device_unregister(dev);
1237
1238         return 0;
1239 }
1240
1241 static void acpi_wmi_remove(struct platform_device *device)
1242 {
1243         struct device *wmi_bus_device = dev_get_drvdata(&device->dev);
1244
1245         device_for_each_child_reverse(wmi_bus_device, NULL, wmi_remove_device);
1246 }
1247
1248 static void acpi_wmi_remove_notify_handler(void *data)
1249 {
1250         struct acpi_device *acpi_device = data;
1251
1252         acpi_remove_notify_handler(acpi_device->handle, ACPI_ALL_NOTIFY, acpi_wmi_notify_handler);
1253 }
1254
1255 static void acpi_wmi_remove_bus_device(void *data)
1256 {
1257         struct device *wmi_bus_dev = data;
1258
1259         device_unregister(wmi_bus_dev);
1260 }
1261
1262 static int acpi_wmi_probe(struct platform_device *device)
1263 {
1264         struct acpi_device *acpi_device;
1265         struct device *wmi_bus_dev;
1266         acpi_status status;
1267         int error;
1268
1269         acpi_device = ACPI_COMPANION(&device->dev);
1270         if (!acpi_device) {
1271                 dev_err(&device->dev, "ACPI companion is missing\n");
1272                 return -ENODEV;
1273         }
1274
1275         wmi_bus_dev = device_create(&wmi_bus_class, &device->dev, MKDEV(0, 0), NULL, "wmi_bus-%s",
1276                                     dev_name(&device->dev));
1277         if (IS_ERR(wmi_bus_dev))
1278                 return PTR_ERR(wmi_bus_dev);
1279
1280         error = devm_add_action_or_reset(&device->dev, acpi_wmi_remove_bus_device, wmi_bus_dev);
1281         if (error < 0)
1282                 return error;
1283
1284         dev_set_drvdata(&device->dev, wmi_bus_dev);
1285
1286         status = acpi_install_notify_handler(acpi_device->handle, ACPI_ALL_NOTIFY,
1287                                              acpi_wmi_notify_handler, wmi_bus_dev);
1288         if (ACPI_FAILURE(status)) {
1289                 dev_err(&device->dev, "Error installing notify handler\n");
1290                 return -ENODEV;
1291         }
1292         error = devm_add_action_or_reset(&device->dev, acpi_wmi_remove_notify_handler,
1293                                          acpi_device);
1294         if (error < 0)
1295                 return error;
1296
1297         error = parse_wdg(wmi_bus_dev, device);
1298         if (error) {
1299                 dev_err(&device->dev, "Failed to parse _WDG method\n");
1300                 return error;
1301         }
1302
1303         return 0;
1304 }
1305
1306 int __must_check __wmi_driver_register(struct wmi_driver *driver,
1307                                        struct module *owner)
1308 {
1309         driver->driver.owner = owner;
1310         driver->driver.bus = &wmi_bus_type;
1311
1312         return driver_register(&driver->driver);
1313 }
1314 EXPORT_SYMBOL(__wmi_driver_register);
1315
1316 /**
1317  * wmi_driver_unregister() - Unregister a WMI driver
1318  * @driver: WMI driver to unregister
1319  *
1320  * Unregisters a WMI driver from the WMI bus.
1321  */
1322 void wmi_driver_unregister(struct wmi_driver *driver)
1323 {
1324         driver_unregister(&driver->driver);
1325 }
1326 EXPORT_SYMBOL(wmi_driver_unregister);
1327
1328 static struct platform_driver acpi_wmi_driver = {
1329         .driver = {
1330                 .name = "acpi-wmi",
1331                 .acpi_match_table = wmi_device_ids,
1332         },
1333         .probe = acpi_wmi_probe,
1334         .remove = acpi_wmi_remove,
1335 };
1336
1337 static int __init acpi_wmi_init(void)
1338 {
1339         int error;
1340
1341         if (acpi_disabled)
1342                 return -ENODEV;
1343
1344         error = class_register(&wmi_bus_class);
1345         if (error)
1346                 return error;
1347
1348         error = bus_register(&wmi_bus_type);
1349         if (error)
1350                 goto err_unreg_class;
1351
1352         error = platform_driver_register(&acpi_wmi_driver);
1353         if (error) {
1354                 pr_err("Error loading mapper\n");
1355                 goto err_unreg_bus;
1356         }
1357
1358         return 0;
1359
1360 err_unreg_bus:
1361         bus_unregister(&wmi_bus_type);
1362
1363 err_unreg_class:
1364         class_unregister(&wmi_bus_class);
1365
1366         return error;
1367 }
1368
1369 static void __exit acpi_wmi_exit(void)
1370 {
1371         platform_driver_unregister(&acpi_wmi_driver);
1372         bus_unregister(&wmi_bus_type);
1373         class_unregister(&wmi_bus_class);
1374 }
1375
1376 subsys_initcall_sync(acpi_wmi_init);
1377 module_exit(acpi_wmi_exit);