drivers/acpi/utils.c

   1 /*
   2  *  acpi_utils.c - ACPI Utility Functions ($Revision: 10 $)
   3  *
   4  *  Copyright (C) 2001, 2002 Andy Grover <[email protected]>
   5  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <[email protected]>
   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 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/slab.h>
  25 #include <linux/init.h>
  26 #include <linux/types.h>
  27 #include <linux/hardirq.h>
  28 #include <linux/acpi.h>
  29 #include <linux/dynamic_debug.h>
  30
  31 #include "internal.h"
  32 #include "sleep.h"
  33
  34 #define _COMPONENT              ACPI_BUS_COMPONENT
  35 ACPI_MODULE_NAME("utils");
  36
  37 /* --------------------------------------------------------------------------
  38                             Object Evaluation Helpers
  39    -------------------------------------------------------------------------- */
  40 static void
  41 acpi_util_eval_error(acpi_handle h, acpi_string p, acpi_status s)
  42 {
  43 #ifdef ACPI_DEBUG_OUTPUT
  44         char prefix[80] = {'\0'};
  45         struct acpi_buffer buffer = {sizeof(prefix), prefix};
  46         acpi_get_name(h, ACPI_FULL_PATHNAME, &buffer);
  47         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Evaluate [%s.%s]: %s\n",
  48                 (char *) prefix, p, acpi_format_exception(s)));
  49 #else
  50         return;
  51 #endif
  52 }
  53
  54 acpi_status
  55 acpi_extract_package(union acpi_object *package,
  56                      struct acpi_buffer *format, struct acpi_buffer *buffer)
  57 {
  58         u32 size_required = 0;
  59         u32 tail_offset = 0;
  60         char *format_string = NULL;
  61         u32 format_count = 0;
  62         u32 i = 0;
  63         u8 *head = NULL;
  64         u8 *tail = NULL;
  65
  66
  67         if (!package || (package->type != ACPI_TYPE_PACKAGE)
  68             || (package->package.count < 1)) {
  69                 printk(KERN_WARNING PREFIX "Invalid package argument\n");
  70                 return AE_BAD_PARAMETER;
  71         }
  72
  73         if (!format || !format->pointer || (format->length < 1)) {
  74                 printk(KERN_WARNING PREFIX "Invalid format argument\n");
  75                 return AE_BAD_PARAMETER;
  76         }
  77
  78         if (!buffer) {
  79                 printk(KERN_WARNING PREFIX "Invalid buffer argument\n");
  80                 return AE_BAD_PARAMETER;
  81         }
  82
  83         format_count = (format->length / sizeof(char)) - 1;
  84         if (format_count > package->package.count) {
  85                 printk(KERN_WARNING PREFIX "Format specifies more objects [%d]"
  86                               " than exist in package [%d].\n",
  87                               format_count, package->package.count);
  88                 return AE_BAD_DATA;
  89         }
  90
  91         format_string = format->pointer;
  92
  93         /*
  94          * Calculate size_required.
  95          */
  96         for (i = 0; i < format_count; i++) {
  97
  98                 union acpi_object *element = &(package->package.elements[i]);
  99
 100                 switch (element->type) {
 101
 102                 case ACPI_TYPE_INTEGER:
 103                         switch (format_string[i]) {
 104                         case 'N':
 105                                 size_required += sizeof(u64);
 106                                 tail_offset += sizeof(u64);
 107                                 break;
 108                         case 'S':
 109                                 size_required +=
 110                                     sizeof(char *) + sizeof(u64) +
 111                                     sizeof(char);
 112                                 tail_offset += sizeof(char *);
 113                                 break;
 114                         default:
 115                                 printk(KERN_WARNING PREFIX "Invalid package element"
 116                                               " [%d]: got number, expecting"
 117                                               " [%c]\n",
 118                                               i, format_string[i]);
 119                                 return AE_BAD_DATA;
 120                                 break;
 121                         }
 122                         break;
 123
 124                 case ACPI_TYPE_STRING:
 125                 case ACPI_TYPE_BUFFER:
 126                         switch (format_string[i]) {
 127                         case 'S':
 128                                 size_required +=
 129                                     sizeof(char *) +
 130                                     (element->string.length * sizeof(char)) +
 131                                     sizeof(char);
 132                                 tail_offset += sizeof(char *);
 133                                 break;
 134                         case 'B':
 135                                 size_required +=
 136                                     sizeof(u8 *) + element->buffer.length;
 137                                 tail_offset += sizeof(u8 *);
 138                                 break;
 139                         default:
 140                                 printk(KERN_WARNING PREFIX "Invalid package element"
 141                                               " [%d] got string/buffer,"
 142                                               " expecting [%c]\n",
 143                                               i, format_string[i]);
 144                                 return AE_BAD_DATA;
 145                                 break;
 146                         }
 147                         break;
 148                 case ACPI_TYPE_LOCAL_REFERENCE:
 149                         switch (format_string[i]) {
 150                         case 'R':
 151                                 size_required += sizeof(void *);
 152                                 tail_offset += sizeof(void *);
 153                                 break;
 154                         default:
 155                                 printk(KERN_WARNING PREFIX "Invalid package element"
 156                                               " [%d] got reference,"
 157                                               " expecting [%c]\n",
 158                                               i, format_string[i]);
 159                                 return AE_BAD_DATA;
 160                                 break;
 161                         }
 162                         break;
 163
 164                 case ACPI_TYPE_PACKAGE:
 165                 default:
 166                         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 167                                           "Found unsupported element at index=%d\n",
 168                                           i));
 169                         /* TBD: handle nested packages... */
 170                         return AE_SUPPORT;
 171                         break;
 172                 }
 173         }
 174
 175         /*
 176          * Validate output buffer.
 177          */
 178         if (buffer->length == ACPI_ALLOCATE_BUFFER) {
 179                 buffer->pointer = ACPI_ALLOCATE_ZEROED(size_required);
 180                 if (!buffer->pointer)
 181                         return AE_NO_MEMORY;
 182                 buffer->length = size_required;
 183         } else {
 184                 if (buffer->length < size_required) {
 185                         buffer->length = size_required;
 186                         return AE_BUFFER_OVERFLOW;
 187                 } else if (buffer->length != size_required ||
 188                            !buffer->pointer) {
 189                         return AE_BAD_PARAMETER;
 190                 }
 191         }
 192
 193         head = buffer->pointer;
 194         tail = buffer->pointer + tail_offset;
 195
 196         /*
 197          * Extract package data.
 198          */
 199         for (i = 0; i < format_count; i++) {
 200
 201                 u8 **pointer = NULL;
 202                 union acpi_object *element = &(package->package.elements[i]);
 203
 204                 switch (element->type) {
 205
 206                 case ACPI_TYPE_INTEGER:
 207                         switch (format_string[i]) {
 208                         case 'N':
 209                                 *((u64 *) head) =
 210                                     element->integer.value;
 211                                 head += sizeof(u64);
 212                                 break;
 213                         case 'S':
 214                                 pointer = (u8 **) head;
 215                                 *pointer = tail;
 216                                 *((u64 *) tail) =
 217                                     element->integer.value;
 218                                 head += sizeof(u64 *);
 219                                 tail += sizeof(u64);
 220                                 /* NULL terminate string */
 221                                 *tail = (char)0;
 222                                 tail += sizeof(char);
 223                                 break;
 224                         default:
 225                                 /* Should never get here */
 226                                 break;
 227                         }
 228                         break;
 229
 230                 case ACPI_TYPE_STRING:
 231                 case ACPI_TYPE_BUFFER:
 232                         switch (format_string[i]) {
 233                         case 'S':
 234                                 pointer = (u8 **) head;
 235                                 *pointer = tail;
 236                                 memcpy(tail, element->string.pointer,
 237                                        element->string.length);
 238                                 head += sizeof(char *);
 239                                 tail += element->string.length * sizeof(char);
 240                                 /* NULL terminate string */
 241                                 *tail = (char)0;
 242                                 tail += sizeof(char);
 243                                 break;
 244                         case 'B':
 245                                 pointer = (u8 **) head;
 246                                 *pointer = tail;
 247                                 memcpy(tail, element->buffer.pointer,
 248                                        element->buffer.length);
 249                                 head += sizeof(u8 *);
 250                                 tail += element->buffer.length;
 251                                 break;
 252                         default:
 253                                 /* Should never get here */
 254                                 break;
 255                         }
 256                         break;
 257                 case ACPI_TYPE_LOCAL_REFERENCE:
 258                         switch (format_string[i]) {
 259                         case 'R':
 260                                 *(void **)head =
 261                                     (void *)element->reference.handle;
 262                                 head += sizeof(void *);
 263                                 break;
 264                         default:
 265                                 /* Should never get here */
 266                                 break;
 267                         }
 268                         break;
 269                 case ACPI_TYPE_PACKAGE:
 270                         /* TBD: handle nested packages... */
 271                 default:
 272                         /* Should never get here */
 273                         break;
 274                 }
 275         }
 276
 277         return AE_OK;
 278 }
 279
 280 EXPORT_SYMBOL(acpi_extract_package);
 281
 282 acpi_status
 283 acpi_evaluate_integer(acpi_handle handle,
 284                       acpi_string pathname,
 285                       struct acpi_object_list *arguments, unsigned long long *data)
 286 {
 287         acpi_status status = AE_OK;
 288         union acpi_object element;
 289         struct acpi_buffer buffer = { 0, NULL };
 290
 291         if (!data)
 292                 return AE_BAD_PARAMETER;
 293
 294         buffer.length = sizeof(union acpi_object);
 295         buffer.pointer = &element;
 296         status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
 297         if (ACPI_FAILURE(status)) {
 298                 acpi_util_eval_error(handle, pathname, status);
 299                 return status;
 300         }
 301
 302         if (element.type != ACPI_TYPE_INTEGER) {
 303                 acpi_util_eval_error(handle, pathname, AE_BAD_DATA);
 304                 return AE_BAD_DATA;
 305         }
 306
 307         *data = element.integer.value;
 308
 309         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Return value [%llu]\n", *data));
 310
 311         return AE_OK;
 312 }
 313
 314 EXPORT_SYMBOL(acpi_evaluate_integer);
 315
 316 acpi_status
 317 acpi_evaluate_reference(acpi_handle handle,
 318                         acpi_string pathname,
 319                         struct acpi_object_list *arguments,
 320                         struct acpi_handle_list *list)
 321 {
 322         acpi_status status = AE_OK;
 323         union acpi_object *package = NULL;
 324         union acpi_object *element = NULL;
 325         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 326         u32 i = 0;
 327
 328
 329         if (!list) {
 330                 return AE_BAD_PARAMETER;
 331         }
 332
 333         /* Evaluate object. */
 334
 335         status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
 336         if (ACPI_FAILURE(status))
 337                 goto end;
 338
 339         package = buffer.pointer;
 340
 341         if ((buffer.length == 0) || !package) {
 342                 status = AE_BAD_DATA;
 343                 acpi_util_eval_error(handle, pathname, status);
 344                 goto end;
 345         }
 346         if (package->type != ACPI_TYPE_PACKAGE) {
 347                 status = AE_BAD_DATA;
 348                 acpi_util_eval_error(handle, pathname, status);
 349                 goto end;
 350         }
 351         if (!package->package.count) {
 352                 status = AE_BAD_DATA;
 353                 acpi_util_eval_error(handle, pathname, status);
 354                 goto end;
 355         }
 356
 357         if (package->package.count > ACPI_MAX_HANDLES) {
 358                 return AE_NO_MEMORY;
 359         }
 360         list->count = package->package.count;
 361
 362         /* Extract package data. */
 363
 364         for (i = 0; i < list->count; i++) {
 365
 366                 element = &(package->package.elements[i]);
 367
 368                 if (element->type != ACPI_TYPE_LOCAL_REFERENCE) {
 369                         status = AE_BAD_DATA;
 370                         acpi_util_eval_error(handle, pathname, status);
 371                         break;
 372                 }
 373
 374                 if (!element->reference.handle) {
 375                         status = AE_NULL_ENTRY;
 376                         acpi_util_eval_error(handle, pathname, status);
 377                         break;
 378                 }
 379                 /* Get the  acpi_handle. */
 380
 381                 list->handles[i] = element->reference.handle;
 382                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found reference [%p]\n",
 383                                   list->handles[i]));
 384         }
 385
 386       end:
 387         if (ACPI_FAILURE(status)) {
 388                 list->count = 0;
 389                 //kfree(list->handles);
 390         }
 391
 392         kfree(buffer.pointer);
 393
 394         return status;
 395 }
 396
 397 EXPORT_SYMBOL(acpi_evaluate_reference);
 398
 399 acpi_status
 400 acpi_get_physical_device_location(acpi_handle handle, struct acpi_pld_info **pld)
 401 {
 402         acpi_status status;
 403         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 404         union acpi_object *output;
 405
 406         status = acpi_evaluate_object(handle, "_PLD", NULL, &buffer);
 407
 408         if (ACPI_FAILURE(status))
 409                 return status;
 410
 411         output = buffer.pointer;
 412
 413         if (!output || output->type != ACPI_TYPE_PACKAGE
 414             || !output->package.count
 415             || output->package.elements[0].type != ACPI_TYPE_BUFFER
 416             || output->package.elements[0].buffer.length < ACPI_PLD_REV1_BUFFER_SIZE) {
 417                 status = AE_TYPE;
 418                 goto out;
 419         }
 420
 421         status = acpi_decode_pld_buffer(
 422                         output->package.elements[0].buffer.pointer,
 423                         output->package.elements[0].buffer.length,
 424                         pld);
 425
 426 out:
 427         kfree(buffer.pointer);
 428         return status;
 429 }
 430 EXPORT_SYMBOL(acpi_get_physical_device_location);
 431
 432 /**
 433  * acpi_evaluate_ost: Evaluate _OST for hotplug operations
 434  * @handle: ACPI device handle
 435  * @source_event: source event code
 436  * @status_code: status code
 437  * @status_buf: optional detailed information (NULL if none)
 438  *
 439  * Evaluate _OST for hotplug operations. All ACPI hotplug handlers
 440  * must call this function when evaluating _OST for hotplug operations.
 441  * When the platform does not support _OST, this function has no effect.
 442  */
 443 acpi_status
 444 acpi_evaluate_ost(acpi_handle handle, u32 source_event, u32 status_code,
 445                   struct acpi_buffer *status_buf)
 446 {
 447         union acpi_object params[3] = {
 448                 {.type = ACPI_TYPE_INTEGER,},
 449                 {.type = ACPI_TYPE_INTEGER,},
 450                 {.type = ACPI_TYPE_BUFFER,}
 451         };
 452         struct acpi_object_list arg_list = {3, params};
 453
 454         params[0].integer.value = source_event;
 455         params[1].integer.value = status_code;
 456         if (status_buf != NULL) {
 457                 params[2].buffer.pointer = status_buf->pointer;
 458                 params[2].buffer.length = status_buf->length;
 459         } else {
 460                 params[2].buffer.pointer = NULL;
 461                 params[2].buffer.length = 0;
 462         }
 463
 464         return acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
 465 }
 466 EXPORT_SYMBOL(acpi_evaluate_ost);
 467
 468 /**
 469  * acpi_handle_path: Return the object path of handle
 470  *
 471  * Caller must free the returned buffer
 472  */
 473 static char *acpi_handle_path(acpi_handle handle)
 474 {
 475         struct acpi_buffer buffer = {
 476                 .length = ACPI_ALLOCATE_BUFFER,
 477                 .pointer = NULL
 478         };
 479
 480         if (in_interrupt() ||
 481             acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer) != AE_OK)
 482                 return NULL;
 483         return buffer.pointer;
 484 }
 485
 486 /**
 487  * acpi_handle_printk: Print message with ACPI prefix and object path
 488  *
 489  * This function is called through acpi_handle_<level> macros and prints
 490  * a message with ACPI prefix and object path.  This function acquires
 491  * the global namespace mutex to obtain an object path.  In interrupt
 492  * context, it shows the object path as <n/a>.
 493  */
 494 void
 495 acpi_handle_printk(const char *level, acpi_handle handle, const char *fmt, ...)
 496 {
 497         struct va_format vaf;
 498         va_list args;
 499         const char *path;
 500
 501         va_start(args, fmt);
 502         vaf.fmt = fmt;
 503         vaf.va = &args;
 504
 505         path = acpi_handle_path(handle);
 506         printk("%sACPI: %s: %pV", level, path ? path : "<n/a>" , &vaf);
 507
 508         va_end(args);
 509         kfree(path);
 510 }
 511 EXPORT_SYMBOL(acpi_handle_printk);
 512
 513 #if defined(CONFIG_DYNAMIC_DEBUG)
 514 /**
 515  * __acpi_handle_debug: pr_debug with ACPI prefix and object path
 516  *
 517  * This function is called through acpi_handle_debug macro and debug
 518  * prints a message with ACPI prefix and object path. This function
 519  * acquires the global namespace mutex to obtain an object path.  In
 520  * interrupt context, it shows the object path as <n/a>.
 521  */
 522 void
 523 __acpi_handle_debug(struct _ddebug *descriptor, acpi_handle handle,
 524                     const char *fmt, ...)
 525 {
 526         struct va_format vaf;
 527         va_list args;
 528         const char *path;
 529
 530         va_start(args, fmt);
 531         vaf.fmt = fmt;
 532         vaf.va = &args;
 533
 534         path = acpi_handle_path(handle);
 535         __dynamic_pr_debug(descriptor, "ACPI: %s: %pV", path ? path : "<n/a>", &vaf);
 536
 537         va_end(args);
 538         kfree(path);
 539 }
 540 EXPORT_SYMBOL(__acpi_handle_debug);
 541 #endif
 542
 543 /**
 544  * acpi_has_method: Check whether @handle has a method named @name
 545  * @handle: ACPI device handle
 546  * @name: name of object or method
 547  *
 548  * Check whether @handle has a method named @name.
 549  */
 550 bool acpi_has_method(acpi_handle handle, char *name)
 551 {
 552         acpi_handle tmp;
 553
 554         return ACPI_SUCCESS(acpi_get_handle(handle, name, &tmp));
 555 }
 556 EXPORT_SYMBOL(acpi_has_method);
 557
 558 acpi_status acpi_execute_simple_method(acpi_handle handle, char *method,
 559                                        u64 arg)
 560 {
 561         union acpi_object obj = { .type = ACPI_TYPE_INTEGER };
 562         struct acpi_object_list arg_list = { .count = 1, .pointer = &obj, };
 563
 564         obj.integer.value = arg;
 565
 566         return acpi_evaluate_object(handle, method, &arg_list, NULL);
 567 }
 568 EXPORT_SYMBOL(acpi_execute_simple_method);
 569
 570 /**
 571  * acpi_evaluate_ej0: Evaluate _EJ0 method for hotplug operations
 572  * @handle: ACPI device handle
 573  *
 574  * Evaluate device's _EJ0 method for hotplug operations.
 575  */
 576 acpi_status acpi_evaluate_ej0(acpi_handle handle)
 577 {
 578         acpi_status status;
 579
 580         status = acpi_execute_simple_method(handle, "_EJ0", 1);
 581         if (status == AE_NOT_FOUND)
 582                 acpi_handle_warn(handle, "No _EJ0 support for device\n");
 583         else if (ACPI_FAILURE(status))
 584                 acpi_handle_warn(handle, "Eject failed (0x%x)\n", status);
 585
 586         return status;
 587 }
 588
 589 /**
 590  * acpi_evaluate_lck: Evaluate _LCK method to lock/unlock device
 591  * @handle: ACPI device handle
 592  * @lock: lock device if non-zero, otherwise unlock device
 593  *
 594  * Evaluate device's _LCK method if present to lock/unlock device
 595  */
 596 acpi_status acpi_evaluate_lck(acpi_handle handle, int lock)
 597 {
 598         acpi_status status;
 599
 600         status = acpi_execute_simple_method(handle, "_LCK", !!lock);
 601         if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
 602                 if (lock)
 603                         acpi_handle_warn(handle,
 604                                 "Locking device failed (0x%x)\n", status);
 605                 else
 606                         acpi_handle_warn(handle,
 607                                 "Unlocking device failed (0x%x)\n", status);
 608         }
 609
 610         return status;
 611 }
 612
 613 /**
 614  * acpi_evaluate_dsm - evaluate device's _DSM method
 615  * @handle: ACPI device handle
 616  * @uuid: UUID of requested functions, should be 16 bytes
 617  * @rev: revision number of requested function
 618  * @func: requested function number
 619  * @argv4: the function specific parameter
 620  *
 621  * Evaluate device's _DSM method with specified UUID, revision id and
 622  * function number. Caller needs to free the returned object.
 623  *
 624  * Though ACPI defines the fourth parameter for _DSM should be a package,
 625  * some old BIOSes do expect a buffer or an integer etc.
 626  */
 627 union acpi_object *
 628 acpi_evaluate_dsm(acpi_handle handle, const u8 *uuid, u64 rev, u64 func,
 629                   union acpi_object *argv4)
 630 {
 631         acpi_status ret;
 632         struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
 633         union acpi_object params[4];
 634         struct acpi_object_list input = {
 635                 .count = 4,
 636                 .pointer = params,
 637         };
 638
 639         params[0].type = ACPI_TYPE_BUFFER;
 640         params[0].buffer.length = 16;
 641         params[0].buffer.pointer = (char *)uuid;
 642         params[1].type = ACPI_TYPE_INTEGER;
 643         params[1].integer.value = rev;
 644         params[2].type = ACPI_TYPE_INTEGER;
 645         params[2].integer.value = func;
 646         if (argv4) {
 647                 params[3] = *argv4;
 648         } else {
 649                 params[3].type = ACPI_TYPE_PACKAGE;
 650                 params[3].package.count = 0;
 651                 params[3].package.elements = NULL;
 652         }
 653
 654         ret = acpi_evaluate_object(handle, "_DSM", &input, &buf);
 655         if (ACPI_SUCCESS(ret))
 656                 return (union acpi_object *)buf.pointer;
 657
 658         if (ret != AE_NOT_FOUND)
 659                 acpi_handle_warn(handle,
 660                                 "failed to evaluate _DSM (0x%x)\n", ret);
 661
 662         return NULL;
 663 }
 664 EXPORT_SYMBOL(acpi_evaluate_dsm);
 665
 666 /**
 667  * acpi_check_dsm - check if _DSM method supports requested functions.
 668  * @handle: ACPI device handle
 669  * @uuid: UUID of requested functions, should be 16 bytes at least
 670  * @rev: revision number of requested functions
 671  * @funcs: bitmap of requested functions
 672  *
 673  * Evaluate device's _DSM method to check whether it supports requested
 674  * functions. Currently only support 64 functions at maximum, should be
 675  * enough for now.
 676  */
 677 bool acpi_check_dsm(acpi_handle handle, const u8 *uuid, u64 rev, u64 funcs)
 678 {
 679         int i;
 680         u64 mask = 0;
 681         union acpi_object *obj;
 682
 683         obj = acpi_evaluate_dsm(handle, uuid, rev, 0, NULL);
 684         if (!obj)
 685                 return false;
 686
 687         /* For compatibility, old BIOSes may return an integer */
 688         if (obj->type == ACPI_TYPE_INTEGER)
 689                 mask = obj->integer.value;
 690         else if (obj->type == ACPI_TYPE_BUFFER)
 691                 for (i = 0; i < obj->buffer.length && i < 8; i++)
 692                         mask |= (((u64)obj->buffer.pointer[i]) << (i * 8));
 693         ACPI_FREE(obj);
 694
 695         if (funcs == 0)
 696                 return true;
 697
 698         /*
 699          * Bit 0 indicates whether there's support for any functions other than
 700          * function 0 for the specified UUID and revision.
 701          */
 702         if ((mask & 0x1) && (mask & funcs) == funcs)
 703                 return true;
 704
 705         return false;
 706 }
 707 EXPORT_SYMBOL(acpi_check_dsm);
 708
 709 /**
 710  * acpi_dev_found - Detect presence of a given ACPI device in the namespace.
 711  * @hid: Hardware ID of the device.
 712  *
 713  * Return %true if the device was present at the moment of invocation.
 714  * Note that if the device is pluggable, it may since have disappeared.
 715  *
 716  * For this function to work, acpi_bus_scan() must have been executed
 717  * which happens in the subsys_initcall() subsection. Hence, do not
 718  * call from a subsys_initcall() or earlier (use acpi_get_devices()
 719  * instead). Calling from module_init() is fine (which is synonymous
 720  * with device_initcall()).
 721  */
 722 bool acpi_dev_found(const char *hid)
 723 {
 724         struct acpi_device_bus_id *acpi_device_bus_id;
 725         bool found = false;
 726
 727         mutex_lock(&acpi_device_lock);
 728         list_for_each_entry(acpi_device_bus_id, &acpi_bus_id_list, node)
 729                 if (!strcmp(acpi_device_bus_id->bus_id, hid)) {
 730                         found = true;
 731                         break;
 732                 }
 733         mutex_unlock(&acpi_device_lock);
 734
 735         return found;
 736 }
 737 EXPORT_SYMBOL(acpi_dev_found);
 738
 739 /*
 740  * acpi_backlight= handling, this is done here rather then in video_detect.c
 741  * because __setup cannot be used in modules.
 742  */
 743 char acpi_video_backlight_string[16];
 744 EXPORT_SYMBOL(acpi_video_backlight_string);
 745
 746 static int __init acpi_backlight(char *str)
 747 {
 748         strlcpy(acpi_video_backlight_string, str,
 749                 sizeof(acpi_video_backlight_string));
 750         return 1;
 751 }
 752 __setup("acpi_backlight=", acpi_backlight);