drivers/acpi/utils.c

   1 /*
   2  *  acpi_utils.c - ACPI Utility Functions ($Revision: 10 $)
   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 #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                 if (!element) {
 205                         return AE_BAD_DATA;
 206                 }
 207
 208                 switch (element->type) {
 209
 210                 case ACPI_TYPE_INTEGER:
 211                         switch (format_string[i]) {
 212                         case 'N':
 213                                 *((u64 *) head) =
 214                                     element->integer.value;
 215                                 head += sizeof(u64);
 216                                 break;
 217                         case 'S':
 218                                 pointer = (u8 **) head;
 219                                 *pointer = tail;
 220                                 *((u64 *) tail) =
 221                                     element->integer.value;
 222                                 head += sizeof(u64 *);
 223                                 tail += sizeof(u64);
 224                                 /* NULL terminate string */
 225                                 *tail = (char)0;
 226                                 tail += sizeof(char);
 227                                 break;
 228                         default:
 229                                 /* Should never get here */
 230                                 break;
 231                         }
 232                         break;
 233
 234                 case ACPI_TYPE_STRING:
 235                 case ACPI_TYPE_BUFFER:
 236                         switch (format_string[i]) {
 237                         case 'S':
 238                                 pointer = (u8 **) head;
 239                                 *pointer = tail;
 240                                 memcpy(tail, element->string.pointer,
 241                                        element->string.length);
 242                                 head += sizeof(char *);
 243                                 tail += element->string.length * sizeof(char);
 244                                 /* NULL terminate string */
 245                                 *tail = (char)0;
 246                                 tail += sizeof(char);
 247                                 break;
 248                         case 'B':
 249                                 pointer = (u8 **) head;
 250                                 *pointer = tail;
 251                                 memcpy(tail, element->buffer.pointer,
 252                                        element->buffer.length);
 253                                 head += sizeof(u8 *);
 254                                 tail += element->buffer.length;
 255                                 break;
 256                         default:
 257                                 /* Should never get here */
 258                                 break;
 259                         }
 260                         break;
 261                 case ACPI_TYPE_LOCAL_REFERENCE:
 262                         switch (format_string[i]) {
 263                         case 'R':
 264                                 *(void **)head =
 265                                     (void *)element->reference.handle;
 266                                 head += sizeof(void *);
 267                                 break;
 268                         default:
 269                                 /* Should never get here */
 270                                 break;
 271                         }
 272                         break;
 273                 case ACPI_TYPE_PACKAGE:
 274                         /* TBD: handle nested packages... */
 275                 default:
 276                         /* Should never get here */
 277                         break;
 278                 }
 279         }
 280
 281         return AE_OK;
 282 }
 283
 284 EXPORT_SYMBOL(acpi_extract_package);
 285
 286 acpi_status
 287 acpi_evaluate_integer(acpi_handle handle,
 288                       acpi_string pathname,
 289                       struct acpi_object_list *arguments, unsigned long long *data)
 290 {
 291         acpi_status status = AE_OK;
 292         union acpi_object element;
 293         struct acpi_buffer buffer = { 0, NULL };
 294
 295         if (!data)
 296                 return AE_BAD_PARAMETER;
 297
 298         buffer.length = sizeof(union acpi_object);
 299         buffer.pointer = &element;
 300         status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
 301         if (ACPI_FAILURE(status)) {
 302                 acpi_util_eval_error(handle, pathname, status);
 303                 return status;
 304         }
 305
 306         if (element.type != ACPI_TYPE_INTEGER) {
 307                 acpi_util_eval_error(handle, pathname, AE_BAD_DATA);
 308                 return AE_BAD_DATA;
 309         }
 310
 311         *data = element.integer.value;
 312
 313         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Return value [%llu]\n", *data));
 314
 315         return AE_OK;
 316 }
 317
 318 EXPORT_SYMBOL(acpi_evaluate_integer);
 319
 320 acpi_status
 321 acpi_evaluate_reference(acpi_handle handle,
 322                         acpi_string pathname,
 323                         struct acpi_object_list *arguments,
 324                         struct acpi_handle_list *list)
 325 {
 326         acpi_status status = AE_OK;
 327         union acpi_object *package = NULL;
 328         union acpi_object *element = NULL;
 329         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 330         u32 i = 0;
 331
 332
 333         if (!list) {
 334                 return AE_BAD_PARAMETER;
 335         }
 336
 337         /* Evaluate object. */
 338
 339         status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
 340         if (ACPI_FAILURE(status))
 341                 goto end;
 342
 343         package = buffer.pointer;
 344
 345         if ((buffer.length == 0) || !package) {
 346                 status = AE_BAD_DATA;
 347                 acpi_util_eval_error(handle, pathname, status);
 348                 goto end;
 349         }
 350         if (package->type != ACPI_TYPE_PACKAGE) {
 351                 status = AE_BAD_DATA;
 352                 acpi_util_eval_error(handle, pathname, status);
 353                 goto end;
 354         }
 355         if (!package->package.count) {
 356                 status = AE_BAD_DATA;
 357                 acpi_util_eval_error(handle, pathname, status);
 358                 goto end;
 359         }
 360
 361         if (package->package.count > ACPI_MAX_HANDLES) {
 362                 return AE_NO_MEMORY;
 363         }
 364         list->count = package->package.count;
 365
 366         /* Extract package data. */
 367
 368         for (i = 0; i < list->count; i++) {
 369
 370                 element = &(package->package.elements[i]);
 371
 372                 if (element->type != ACPI_TYPE_LOCAL_REFERENCE) {
 373                         status = AE_BAD_DATA;
 374                         acpi_util_eval_error(handle, pathname, status);
 375                         break;
 376                 }
 377
 378                 if (!element->reference.handle) {
 379                         status = AE_NULL_ENTRY;
 380                         acpi_util_eval_error(handle, pathname, status);
 381                         break;
 382                 }
 383                 /* Get the  acpi_handle. */
 384
 385                 list->handles[i] = element->reference.handle;
 386                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found reference [%p]\n",
 387                                   list->handles[i]));
 388         }
 389
 390       end:
 391         if (ACPI_FAILURE(status)) {
 392                 list->count = 0;
 393                 //kfree(list->handles);
 394         }
 395
 396         kfree(buffer.pointer);
 397
 398         return status;
 399 }
 400
 401 EXPORT_SYMBOL(acpi_evaluate_reference);
 402
 403 acpi_status
 404 acpi_get_physical_device_location(acpi_handle handle, struct acpi_pld_info **pld)
 405 {
 406         acpi_status status;
 407         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 408         union acpi_object *output;
 409
 410         status = acpi_evaluate_object(handle, "_PLD", NULL, &buffer);
 411
 412         if (ACPI_FAILURE(status))
 413                 return status;
 414
 415         output = buffer.pointer;
 416
 417         if (!output || output->type != ACPI_TYPE_PACKAGE
 418             || !output->package.count
 419             || output->package.elements[0].type != ACPI_TYPE_BUFFER
 420             || output->package.elements[0].buffer.length < ACPI_PLD_REV1_BUFFER_SIZE) {
 421                 status = AE_TYPE;
 422                 goto out;
 423         }
 424
 425         status = acpi_decode_pld_buffer(
 426                         output->package.elements[0].buffer.pointer,
 427                         output->package.elements[0].buffer.length,
 428                         pld);
 429
 430 out:
 431         kfree(buffer.pointer);
 432         return status;
 433 }
 434 EXPORT_SYMBOL(acpi_get_physical_device_location);
 435
 436 /**
 437  * acpi_evaluate_ost: Evaluate _OST for hotplug operations
 438  * @handle: ACPI device handle
 439  * @source_event: source event code
 440  * @status_code: status code
 441  * @status_buf: optional detailed information (NULL if none)
 442  *
 443  * Evaluate _OST for hotplug operations. All ACPI hotplug handlers
 444  * must call this function when evaluating _OST for hotplug operations.
 445  * When the platform does not support _OST, this function has no effect.
 446  */
 447 acpi_status
 448 acpi_evaluate_ost(acpi_handle handle, u32 source_event, u32 status_code,
 449                   struct acpi_buffer *status_buf)
 450 {
 451         union acpi_object params[3] = {
 452                 {.type = ACPI_TYPE_INTEGER,},
 453                 {.type = ACPI_TYPE_INTEGER,},
 454                 {.type = ACPI_TYPE_BUFFER,}
 455         };
 456         struct acpi_object_list arg_list = {3, params};
 457
 458         params[0].integer.value = source_event;
 459         params[1].integer.value = status_code;
 460         if (status_buf != NULL) {
 461                 params[2].buffer.pointer = status_buf->pointer;
 462                 params[2].buffer.length = status_buf->length;
 463         } else {
 464                 params[2].buffer.pointer = NULL;
 465                 params[2].buffer.length = 0;
 466         }
 467
 468         return acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
 469 }
 470 EXPORT_SYMBOL(acpi_evaluate_ost);
 471
 472 /**
 473  * acpi_handle_path: Return the object path of handle
 474  *
 475  * Caller must free the returned buffer
 476  */
 477 static char *acpi_handle_path(acpi_handle handle)
 478 {
 479         struct acpi_buffer buffer = {
 480                 .length = ACPI_ALLOCATE_BUFFER,
 481                 .pointer = NULL
 482         };
 483
 484         if (in_interrupt() ||
 485             acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer) != AE_OK)
 486                 return NULL;
 487         return buffer.pointer;
 488 }
 489
 490 /**
 491  * acpi_handle_printk: Print message with ACPI prefix and object path
 492  *
 493  * This function is called through acpi_handle_<level> macros and prints
 494  * a message with ACPI prefix and object path.  This function acquires
 495  * the global namespace mutex to obtain an object path.  In interrupt
 496  * context, it shows the object path as <n/a>.
 497  */
 498 void
 499 acpi_handle_printk(const char *level, acpi_handle handle, const char *fmt, ...)
 500 {
 501         struct va_format vaf;
 502         va_list args;
 503         const char *path;
 504
 505         va_start(args, fmt);
 506         vaf.fmt = fmt;
 507         vaf.va = &args;
 508
 509         path = acpi_handle_path(handle);
 510         printk("%sACPI: %s: %pV", level, path ? path : "<n/a>" , &vaf);
 511
 512         va_end(args);
 513         kfree(path);
 514 }
 515 EXPORT_SYMBOL(acpi_handle_printk);
 516
 517 #if defined(CONFIG_DYNAMIC_DEBUG)
 518 /**
 519  * __acpi_handle_debug: pr_debug with ACPI prefix and object path
 520  *
 521  * This function is called through acpi_handle_debug macro and debug
 522  * prints a message with ACPI prefix and object path. This function
 523  * acquires the global namespace mutex to obtain an object path.  In
 524  * interrupt context, it shows the object path as <n/a>.
 525  */
 526 void
 527 __acpi_handle_debug(struct _ddebug *descriptor, acpi_handle handle,
 528                     const char *fmt, ...)
 529 {
 530         struct va_format vaf;
 531         va_list args;
 532         const char *path;
 533
 534         va_start(args, fmt);
 535         vaf.fmt = fmt;
 536         vaf.va = &args;
 537
 538         path = acpi_handle_path(handle);
 539         __dynamic_pr_debug(descriptor, "ACPI: %s: %pV", path ? path : "<n/a>", &vaf);
 540
 541         va_end(args);
 542         kfree(path);
 543 }
 544 EXPORT_SYMBOL(__acpi_handle_debug);
 545 #endif
 546
 547 /**
 548  * acpi_has_method: Check whether @handle has a method named @name
 549  * @handle: ACPI device handle
 550  * @name: name of object or method
 551  *
 552  * Check whether @handle has a method named @name.
 553  */
 554 bool acpi_has_method(acpi_handle handle, char *name)
 555 {
 556         acpi_handle tmp;
 557
 558         return ACPI_SUCCESS(acpi_get_handle(handle, name, &tmp));
 559 }
 560 EXPORT_SYMBOL(acpi_has_method);
 561
 562 acpi_status acpi_execute_simple_method(acpi_handle handle, char *method,
 563                                        u64 arg)
 564 {
 565         union acpi_object obj = { .type = ACPI_TYPE_INTEGER };
 566         struct acpi_object_list arg_list = { .count = 1, .pointer = &obj, };
 567
 568         obj.integer.value = arg;
 569
 570         return acpi_evaluate_object(handle, method, &arg_list, NULL);
 571 }
 572 EXPORT_SYMBOL(acpi_execute_simple_method);
 573
 574 /**
 575  * acpi_evaluate_ej0: Evaluate _EJ0 method for hotplug operations
 576  * @handle: ACPI device handle
 577  *
 578  * Evaluate device's _EJ0 method for hotplug operations.
 579  */
 580 acpi_status acpi_evaluate_ej0(acpi_handle handle)
 581 {
 582         acpi_status status;
 583
 584         status = acpi_execute_simple_method(handle, "_EJ0", 1);
 585         if (status == AE_NOT_FOUND)
 586                 acpi_handle_warn(handle, "No _EJ0 support for device\n");
 587         else if (ACPI_FAILURE(status))
 588                 acpi_handle_warn(handle, "Eject failed (0x%x)\n", status);
 589
 590         return status;
 591 }
 592
 593 /**
 594  * acpi_evaluate_lck: Evaluate _LCK method to lock/unlock device
 595  * @handle: ACPI device handle
 596  * @lock: lock device if non-zero, otherwise unlock device
 597  *
 598  * Evaluate device's _LCK method if present to lock/unlock device
 599  */
 600 acpi_status acpi_evaluate_lck(acpi_handle handle, int lock)
 601 {
 602         acpi_status status;
 603
 604         status = acpi_execute_simple_method(handle, "_LCK", !!lock);
 605         if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
 606                 if (lock)
 607                         acpi_handle_warn(handle,
 608                                 "Locking device failed (0x%x)\n", status);
 609                 else
 610                         acpi_handle_warn(handle,
 611                                 "Unlocking device failed (0x%x)\n", status);
 612         }
 613
 614         return status;
 615 }
 616
 617 /**
 618  * acpi_evaluate_dsm - evaluate device's _DSM method
 619  * @handle: ACPI device handle
 620  * @uuid: UUID of requested functions, should be 16 bytes
 621  * @rev: revision number of requested function
 622  * @func: requested function number
 623  * @argv4: the function specific parameter
 624  *
 625  * Evaluate device's _DSM method with specified UUID, revision id and
 626  * function number. Caller needs to free the returned object.
 627  *
 628  * Though ACPI defines the fourth parameter for _DSM should be a package,
 629  * some old BIOSes do expect a buffer or an integer etc.
 630  */
 631 union acpi_object *
 632 acpi_evaluate_dsm(acpi_handle handle, const u8 *uuid, int rev, int func,
 633                   union acpi_object *argv4)
 634 {
 635         acpi_status ret;
 636         struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
 637         union acpi_object params[4];
 638         struct acpi_object_list input = {
 639                 .count = 4,
 640                 .pointer = params,
 641         };
 642
 643         params[0].type = ACPI_TYPE_BUFFER;
 644         params[0].buffer.length = 16;
 645         params[0].buffer.pointer = (char *)uuid;
 646         params[1].type = ACPI_TYPE_INTEGER;
 647         params[1].integer.value = rev;
 648         params[2].type = ACPI_TYPE_INTEGER;
 649         params[2].integer.value = func;
 650         if (argv4) {
 651                 params[3] = *argv4;
 652         } else {
 653                 params[3].type = ACPI_TYPE_PACKAGE;
 654                 params[3].package.count = 0;
 655                 params[3].package.elements = NULL;
 656         }
 657
 658         ret = acpi_evaluate_object(handle, "_DSM", &input, &buf);
 659         if (ACPI_SUCCESS(ret))
 660                 return (union acpi_object *)buf.pointer;
 661
 662         if (ret != AE_NOT_FOUND)
 663                 acpi_handle_warn(handle,
 664                                 "failed to evaluate _DSM (0x%x)\n", ret);
 665
 666         return NULL;
 667 }
 668 EXPORT_SYMBOL(acpi_evaluate_dsm);
 669
 670 /**
 671  * acpi_check_dsm - check if _DSM method supports requested functions.
 672  * @handle: ACPI device handle
 673  * @uuid: UUID of requested functions, should be 16 bytes at least
 674  * @rev: revision number of requested functions
 675  * @funcs: bitmap of requested functions
 676  *
 677  * Evaluate device's _DSM method to check whether it supports requested
 678  * functions. Currently only support 64 functions at maximum, should be
 679  * enough for now.
 680  */
 681 bool acpi_check_dsm(acpi_handle handle, const u8 *uuid, int rev, u64 funcs)
 682 {
 683         int i;
 684         u64 mask = 0;
 685         union acpi_object *obj;
 686
 687         if (funcs == 0)
 688                 return false;
 689
 690         obj = acpi_evaluate_dsm(handle, uuid, rev, 0, NULL);
 691         if (!obj)
 692                 return false;
 693
 694         /* For compatibility, old BIOSes may return an integer */
 695         if (obj->type == ACPI_TYPE_INTEGER)
 696                 mask = obj->integer.value;
 697         else if (obj->type == ACPI_TYPE_BUFFER)
 698                 for (i = 0; i < obj->buffer.length && i < 8; i++)
 699                         mask |= (((u8)obj->buffer.pointer[i]) << (i * 8));
 700         ACPI_FREE(obj);
 701
 702         /*
 703          * Bit 0 indicates whether there's support for any functions other than
 704          * function 0 for the specified UUID and revision.
 705          */
 706         if ((mask & 0x1) && (mask & funcs) == funcs)
 707                 return true;
 708
 709         return false;
 710 }
 711 EXPORT_SYMBOL(acpi_check_dsm);
 712
 713 /**
 714  * acpi_dev_present - Detect presence of a given ACPI device in the system.
 715  * @hid: Hardware ID of the device.
 716  *
 717  * Return %true if the device was present at the moment of invocation.
 718  * Note that if the device is pluggable, it may since have disappeared.
 719  *
 720  * For this function to work, acpi_bus_scan() must have been executed
 721  * which happens in the subsys_initcall() subsection. Hence, do not
 722  * call from a subsys_initcall() or earlier (use acpi_get_devices()
 723  * instead). Calling from module_init() is fine (which is synonymous
 724  * with device_initcall()).
 725  */
 726 bool acpi_dev_present(const char *hid)
 727 {
 728         struct acpi_device_bus_id *acpi_device_bus_id;
 729         bool found = false;
 730
 731         mutex_lock(&acpi_device_lock);
 732         list_for_each_entry(acpi_device_bus_id, &acpi_bus_id_list, node)
 733                 if (!strcmp(acpi_device_bus_id->bus_id, hid)) {
 734                         found = true;
 735                         break;
 736                 }
 737         mutex_unlock(&acpi_device_lock);
 738
 739         return found;
 740 }
 741 EXPORT_SYMBOL(acpi_dev_present);
 742
 743 /*
 744  * acpi_backlight= handling, this is done here rather then in video_detect.c
 745  * because __setup cannot be used in modules.
 746  */
 747 char acpi_video_backlight_string[16];
 748 EXPORT_SYMBOL(acpi_video_backlight_string);
 749
 750 static int __init acpi_backlight(char *str)
 751 {
 752         strlcpy(acpi_video_backlight_string, str,
 753                 sizeof(acpi_video_backlight_string));
 754         return 1;
 755 }
 756 __setup("acpi_backlight=", acpi_backlight);