root/drivers/acpi/utils.c

DEFINITIONS

1. acpi_util_eval_error
2. acpi_extract_package
3. acpi_evaluate_integer
4. acpi_evaluate_reference
5. acpi_get_physical_device_location
6. acpi_evaluate_ost
7. acpi_handle_path
8. acpi_handle_printk
9. __acpi_handle_debug
10. acpi_has_method
11. acpi_execute_simple_method
12. acpi_evaluate_ej0
13. acpi_evaluate_lck
14. acpi_evaluate_dsm
15. acpi_check_dsm
16. acpi_dev_found
17. acpi_dev_match_cb
18. acpi_dev_present
19. acpi_dev_get_first_match_dev
20. acpi_backlight
21. acpi_match_platform_list

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  acpi_utils.c - ACPI Utility Functions ($Revision: 10 $)
   4  *
   5  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
   6  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
   7  */
   8 
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/slab.h>
  12 #include <linux/init.h>
  13 #include <linux/types.h>
  14 #include <linux/hardirq.h>
  15 #include <linux/acpi.h>
  16 #include <linux/dynamic_debug.h>
  17 
  18 #include "internal.h"
  19 #include "sleep.h"
  20 
  21 #define _COMPONENT              ACPI_BUS_COMPONENT
  22 ACPI_MODULE_NAME("utils");
  23 
  24 /* --------------------------------------------------------------------------
  25                             Object Evaluation Helpers
  26    -------------------------------------------------------------------------- */
  27 static void
  28 acpi_util_eval_error(acpi_handle h, acpi_string p, acpi_status s)
  29 {
  30 #ifdef ACPI_DEBUG_OUTPUT
  31         char prefix[80] = {'\0'};
  32         struct acpi_buffer buffer = {sizeof(prefix), prefix};
  33         acpi_get_name(h, ACPI_FULL_PATHNAME, &buffer);
  34         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Evaluate [%s.%s]: %s\n",
  35                 (char *) prefix, p, acpi_format_exception(s)));
  36 #else
  37         return;
  38 #endif
  39 }
  40 
  41 acpi_status
  42 acpi_extract_package(union acpi_object *package,
  43                      struct acpi_buffer *format, struct acpi_buffer *buffer)
  44 {
  45         u32 size_required = 0;
  46         u32 tail_offset = 0;
  47         char *format_string = NULL;
  48         u32 format_count = 0;
  49         u32 i = 0;
  50         u8 *head = NULL;
  51         u8 *tail = NULL;
  52 
  53 
  54         if (!package || (package->type != ACPI_TYPE_PACKAGE)
  55             || (package->package.count < 1)) {
  56                 printk(KERN_WARNING PREFIX "Invalid package argument\n");
  57                 return AE_BAD_PARAMETER;
  58         }
  59 
  60         if (!format || !format->pointer || (format->length < 1)) {
  61                 printk(KERN_WARNING PREFIX "Invalid format argument\n");
  62                 return AE_BAD_PARAMETER;
  63         }
  64 
  65         if (!buffer) {
  66                 printk(KERN_WARNING PREFIX "Invalid buffer argument\n");
  67                 return AE_BAD_PARAMETER;
  68         }
  69 
  70         format_count = (format->length / sizeof(char)) - 1;
  71         if (format_count > package->package.count) {
  72                 printk(KERN_WARNING PREFIX "Format specifies more objects [%d]"
  73                               " than exist in package [%d].\n",
  74                               format_count, package->package.count);
  75                 return AE_BAD_DATA;
  76         }
  77 
  78         format_string = format->pointer;
  79 
  80         /*
  81          * Calculate size_required.
  82          */
  83         for (i = 0; i < format_count; i++) {
  84 
  85                 union acpi_object *element = &(package->package.elements[i]);
  86 
  87                 switch (element->type) {
  88 
  89                 case ACPI_TYPE_INTEGER:
  90                         switch (format_string[i]) {
  91                         case 'N':
  92                                 size_required += sizeof(u64);
  93                                 tail_offset += sizeof(u64);
  94                                 break;
  95                         case 'S':
  96                                 size_required +=
  97                                     sizeof(char *) + sizeof(u64) +
  98                                     sizeof(char);
  99                                 tail_offset += sizeof(char *);
 100                                 break;
 101                         default:
 102                                 printk(KERN_WARNING PREFIX "Invalid package element"
 103                                               " [%d]: got number, expecting"
 104                                               " [%c]\n",
 105                                               i, format_string[i]);
 106                                 return AE_BAD_DATA;
 107                                 break;
 108                         }
 109                         break;
 110 
 111                 case ACPI_TYPE_STRING:
 112                 case ACPI_TYPE_BUFFER:
 113                         switch (format_string[i]) {
 114                         case 'S':
 115                                 size_required +=
 116                                     sizeof(char *) +
 117                                     (element->string.length * sizeof(char)) +
 118                                     sizeof(char);
 119                                 tail_offset += sizeof(char *);
 120                                 break;
 121                         case 'B':
 122                                 size_required +=
 123                                     sizeof(u8 *) + element->buffer.length;
 124                                 tail_offset += sizeof(u8 *);
 125                                 break;
 126                         default:
 127                                 printk(KERN_WARNING PREFIX "Invalid package element"
 128                                               " [%d] got string/buffer,"
 129                                               " expecting [%c]\n",
 130                                               i, format_string[i]);
 131                                 return AE_BAD_DATA;
 132                                 break;
 133                         }
 134                         break;
 135                 case ACPI_TYPE_LOCAL_REFERENCE:
 136                         switch (format_string[i]) {
 137                         case 'R':
 138                                 size_required += sizeof(void *);
 139                                 tail_offset += sizeof(void *);
 140                                 break;
 141                         default:
 142                                 printk(KERN_WARNING PREFIX "Invalid package element"
 143                                               " [%d] got reference,"
 144                                               " expecting [%c]\n",
 145                                               i, format_string[i]);
 146                                 return AE_BAD_DATA;
 147                                 break;
 148                         }
 149                         break;
 150 
 151                 case ACPI_TYPE_PACKAGE:
 152                 default:
 153                         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 154                                           "Found unsupported element at index=%d\n",
 155                                           i));
 156                         /* TBD: handle nested packages... */
 157                         return AE_SUPPORT;
 158                         break;
 159                 }
 160         }
 161 
 162         /*
 163          * Validate output buffer.
 164          */
 165         if (buffer->length == ACPI_ALLOCATE_BUFFER) {
 166                 buffer->pointer = ACPI_ALLOCATE_ZEROED(size_required);
 167                 if (!buffer->pointer)
 168                         return AE_NO_MEMORY;
 169                 buffer->length = size_required;
 170         } else {
 171                 if (buffer->length < size_required) {
 172                         buffer->length = size_required;
 173                         return AE_BUFFER_OVERFLOW;
 174                 } else if (buffer->length != size_required ||
 175                            !buffer->pointer) {
 176                         return AE_BAD_PARAMETER;
 177                 }
 178         }
 179 
 180         head = buffer->pointer;
 181         tail = buffer->pointer + tail_offset;
 182 
 183         /*
 184          * Extract package data.
 185          */
 186         for (i = 0; i < format_count; i++) {
 187 
 188                 u8 **pointer = NULL;
 189                 union acpi_object *element = &(package->package.elements[i]);
 190 
 191                 switch (element->type) {
 192 
 193                 case ACPI_TYPE_INTEGER:
 194                         switch (format_string[i]) {
 195                         case 'N':
 196                                 *((u64 *) head) =
 197                                     element->integer.value;
 198                                 head += sizeof(u64);
 199                                 break;
 200                         case 'S':
 201                                 pointer = (u8 **) head;
 202                                 *pointer = tail;
 203                                 *((u64 *) tail) =
 204                                     element->integer.value;
 205                                 head += sizeof(u64 *);
 206                                 tail += sizeof(u64);
 207                                 /* NULL terminate string */
 208                                 *tail = (char)0;
 209                                 tail += sizeof(char);
 210                                 break;
 211                         default:
 212                                 /* Should never get here */
 213                                 break;
 214                         }
 215                         break;
 216 
 217                 case ACPI_TYPE_STRING:
 218                 case ACPI_TYPE_BUFFER:
 219                         switch (format_string[i]) {
 220                         case 'S':
 221                                 pointer = (u8 **) head;
 222                                 *pointer = tail;
 223                                 memcpy(tail, element->string.pointer,
 224                                        element->string.length);
 225                                 head += sizeof(char *);
 226                                 tail += element->string.length * sizeof(char);
 227                                 /* NULL terminate string */
 228                                 *tail = (char)0;
 229                                 tail += sizeof(char);
 230                                 break;
 231                         case 'B':
 232                                 pointer = (u8 **) head;
 233                                 *pointer = tail;
 234                                 memcpy(tail, element->buffer.pointer,
 235                                        element->buffer.length);
 236                                 head += sizeof(u8 *);
 237                                 tail += element->buffer.length;
 238                                 break;
 239                         default:
 240                                 /* Should never get here */
 241                                 break;
 242                         }
 243                         break;
 244                 case ACPI_TYPE_LOCAL_REFERENCE:
 245                         switch (format_string[i]) {
 246                         case 'R':
 247                                 *(void **)head =
 248                                     (void *)element->reference.handle;
 249                                 head += sizeof(void *);
 250                                 break;
 251                         default:
 252                                 /* Should never get here */
 253                                 break;
 254                         }
 255                         break;
 256                 case ACPI_TYPE_PACKAGE:
 257                         /* TBD: handle nested packages... */
 258                 default:
 259                         /* Should never get here */
 260                         break;
 261                 }
 262         }
 263 
 264         return AE_OK;
 265 }
 266 
 267 EXPORT_SYMBOL(acpi_extract_package);
 268 
 269 acpi_status
 270 acpi_evaluate_integer(acpi_handle handle,
 271                       acpi_string pathname,
 272                       struct acpi_object_list *arguments, unsigned long long *data)
 273 {
 274         acpi_status status = AE_OK;
 275         union acpi_object element;
 276         struct acpi_buffer buffer = { 0, NULL };
 277 
 278         if (!data)
 279                 return AE_BAD_PARAMETER;
 280 
 281         buffer.length = sizeof(union acpi_object);
 282         buffer.pointer = &element;
 283         status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
 284         if (ACPI_FAILURE(status)) {
 285                 acpi_util_eval_error(handle, pathname, status);
 286                 return status;
 287         }
 288 
 289         if (element.type != ACPI_TYPE_INTEGER) {
 290                 acpi_util_eval_error(handle, pathname, AE_BAD_DATA);
 291                 return AE_BAD_DATA;
 292         }
 293 
 294         *data = element.integer.value;
 295 
 296         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Return value [%llu]\n", *data));
 297 
 298         return AE_OK;
 299 }
 300 
 301 EXPORT_SYMBOL(acpi_evaluate_integer);
 302 
 303 acpi_status
 304 acpi_evaluate_reference(acpi_handle handle,
 305                         acpi_string pathname,
 306                         struct acpi_object_list *arguments,
 307                         struct acpi_handle_list *list)
 308 {
 309         acpi_status status = AE_OK;
 310         union acpi_object *package = NULL;
 311         union acpi_object *element = NULL;
 312         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 313         u32 i = 0;
 314 
 315 
 316         if (!list) {
 317                 return AE_BAD_PARAMETER;
 318         }
 319 
 320         /* Evaluate object. */
 321 
 322         status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
 323         if (ACPI_FAILURE(status))
 324                 goto end;
 325 
 326         package = buffer.pointer;
 327 
 328         if ((buffer.length == 0) || !package) {
 329                 status = AE_BAD_DATA;
 330                 acpi_util_eval_error(handle, pathname, status);
 331                 goto end;
 332         }
 333         if (package->type != ACPI_TYPE_PACKAGE) {
 334                 status = AE_BAD_DATA;
 335                 acpi_util_eval_error(handle, pathname, status);
 336                 goto end;
 337         }
 338         if (!package->package.count) {
 339                 status = AE_BAD_DATA;
 340                 acpi_util_eval_error(handle, pathname, status);
 341                 goto end;
 342         }
 343 
 344         if (package->package.count > ACPI_MAX_HANDLES) {
 345                 kfree(package);
 346                 return AE_NO_MEMORY;
 347         }
 348         list->count = package->package.count;
 349 
 350         /* Extract package data. */
 351 
 352         for (i = 0; i < list->count; i++) {
 353 
 354                 element = &(package->package.elements[i]);
 355 
 356                 if (element->type != ACPI_TYPE_LOCAL_REFERENCE) {
 357                         status = AE_BAD_DATA;
 358                         acpi_util_eval_error(handle, pathname, status);
 359                         break;
 360                 }
 361 
 362                 if (!element->reference.handle) {
 363                         status = AE_NULL_ENTRY;
 364                         acpi_util_eval_error(handle, pathname, status);
 365                         break;
 366                 }
 367                 /* Get the  acpi_handle. */
 368 
 369                 list->handles[i] = element->reference.handle;
 370                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found reference [%p]\n",
 371                                   list->handles[i]));
 372         }
 373 
 374       end:
 375         if (ACPI_FAILURE(status)) {
 376                 list->count = 0;
 377                 //kfree(list->handles);
 378         }
 379 
 380         kfree(buffer.pointer);
 381 
 382         return status;
 383 }
 384 
 385 EXPORT_SYMBOL(acpi_evaluate_reference);
 386 
 387 acpi_status
 388 acpi_get_physical_device_location(acpi_handle handle, struct acpi_pld_info **pld)
 389 {
 390         acpi_status status;
 391         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 392         union acpi_object *output;
 393 
 394         status = acpi_evaluate_object(handle, "_PLD", NULL, &buffer);
 395 
 396         if (ACPI_FAILURE(status))
 397                 return status;
 398 
 399         output = buffer.pointer;
 400 
 401         if (!output || output->type != ACPI_TYPE_PACKAGE
 402             || !output->package.count
 403             || output->package.elements[0].type != ACPI_TYPE_BUFFER
 404             || output->package.elements[0].buffer.length < ACPI_PLD_REV1_BUFFER_SIZE) {
 405                 status = AE_TYPE;
 406                 goto out;
 407         }
 408 
 409         status = acpi_decode_pld_buffer(
 410                         output->package.elements[0].buffer.pointer,
 411                         output->package.elements[0].buffer.length,
 412                         pld);
 413 
 414 out:
 415         kfree(buffer.pointer);
 416         return status;
 417 }
 418 EXPORT_SYMBOL(acpi_get_physical_device_location);
 419 
 420 /**
 421  * acpi_evaluate_ost: Evaluate _OST for hotplug operations
 422  * @handle: ACPI device handle
 423  * @source_event: source event code
 424  * @status_code: status code
 425  * @status_buf: optional detailed information (NULL if none)
 426  *
 427  * Evaluate _OST for hotplug operations. All ACPI hotplug handlers
 428  * must call this function when evaluating _OST for hotplug operations.
 429  * When the platform does not support _OST, this function has no effect.
 430  */
 431 acpi_status
 432 acpi_evaluate_ost(acpi_handle handle, u32 source_event, u32 status_code,
 433                   struct acpi_buffer *status_buf)
 434 {
 435         union acpi_object params[3] = {
 436                 {.type = ACPI_TYPE_INTEGER,},
 437                 {.type = ACPI_TYPE_INTEGER,},
 438                 {.type = ACPI_TYPE_BUFFER,}
 439         };
 440         struct acpi_object_list arg_list = {3, params};
 441 
 442         params[0].integer.value = source_event;
 443         params[1].integer.value = status_code;
 444         if (status_buf != NULL) {
 445                 params[2].buffer.pointer = status_buf->pointer;
 446                 params[2].buffer.length = status_buf->length;
 447         } else {
 448                 params[2].buffer.pointer = NULL;
 449                 params[2].buffer.length = 0;
 450         }
 451 
 452         return acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
 453 }
 454 EXPORT_SYMBOL(acpi_evaluate_ost);
 455 
 456 /**
 457  * acpi_handle_path: Return the object path of handle
 458  *
 459  * Caller must free the returned buffer
 460  */
 461 static char *acpi_handle_path(acpi_handle handle)
 462 {
 463         struct acpi_buffer buffer = {
 464                 .length = ACPI_ALLOCATE_BUFFER,
 465                 .pointer = NULL
 466         };
 467 
 468         if (in_interrupt() ||
 469             acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer) != AE_OK)
 470                 return NULL;
 471         return buffer.pointer;
 472 }
 473 
 474 /**
 475  * acpi_handle_printk: Print message with ACPI prefix and object path
 476  *
 477  * This function is called through acpi_handle_<level> macros and prints
 478  * a message with ACPI prefix and object path.  This function acquires
 479  * the global namespace mutex to obtain an object path.  In interrupt
 480  * context, it shows the object path as <n/a>.
 481  */
 482 void
 483 acpi_handle_printk(const char *level, acpi_handle handle, const char *fmt, ...)
 484 {
 485         struct va_format vaf;
 486         va_list args;
 487         const char *path;
 488 
 489         va_start(args, fmt);
 490         vaf.fmt = fmt;
 491         vaf.va = &args;
 492 
 493         path = acpi_handle_path(handle);
 494         printk("%sACPI: %s: %pV", level, path ? path : "<n/a>" , &vaf);
 495 
 496         va_end(args);
 497         kfree(path);
 498 }
 499 EXPORT_SYMBOL(acpi_handle_printk);
 500 
 501 #if defined(CONFIG_DYNAMIC_DEBUG)
 502 /**
 503  * __acpi_handle_debug: pr_debug with ACPI prefix and object path
 504  *
 505  * This function is called through acpi_handle_debug macro and debug
 506  * prints a message with ACPI prefix and object path. This function
 507  * acquires the global namespace mutex to obtain an object path.  In
 508  * interrupt context, it shows the object path as <n/a>.
 509  */
 510 void
 511 __acpi_handle_debug(struct _ddebug *descriptor, acpi_handle handle,
 512                     const char *fmt, ...)
 513 {
 514         struct va_format vaf;
 515         va_list args;
 516         const char *path;
 517 
 518         va_start(args, fmt);
 519         vaf.fmt = fmt;
 520         vaf.va = &args;
 521 
 522         path = acpi_handle_path(handle);
 523         __dynamic_pr_debug(descriptor, "ACPI: %s: %pV", path ? path : "<n/a>", &vaf);
 524 
 525         va_end(args);
 526         kfree(path);
 527 }
 528 EXPORT_SYMBOL(__acpi_handle_debug);
 529 #endif
 530 
 531 /**
 532  * acpi_has_method: Check whether @handle has a method named @name
 533  * @handle: ACPI device handle
 534  * @name: name of object or method
 535  *
 536  * Check whether @handle has a method named @name.
 537  */
 538 bool acpi_has_method(acpi_handle handle, char *name)
 539 {
 540         acpi_handle tmp;
 541 
 542         return ACPI_SUCCESS(acpi_get_handle(handle, name, &tmp));
 543 }
 544 EXPORT_SYMBOL(acpi_has_method);
 545 
 546 acpi_status acpi_execute_simple_method(acpi_handle handle, char *method,
 547                                        u64 arg)
 548 {
 549         union acpi_object obj = { .type = ACPI_TYPE_INTEGER };
 550         struct acpi_object_list arg_list = { .count = 1, .pointer = &obj, };
 551 
 552         obj.integer.value = arg;
 553 
 554         return acpi_evaluate_object(handle, method, &arg_list, NULL);
 555 }
 556 EXPORT_SYMBOL(acpi_execute_simple_method);
 557 
 558 /**
 559  * acpi_evaluate_ej0: Evaluate _EJ0 method for hotplug operations
 560  * @handle: ACPI device handle
 561  *
 562  * Evaluate device's _EJ0 method for hotplug operations.
 563  */
 564 acpi_status acpi_evaluate_ej0(acpi_handle handle)
 565 {
 566         acpi_status status;
 567 
 568         status = acpi_execute_simple_method(handle, "_EJ0", 1);
 569         if (status == AE_NOT_FOUND)
 570                 acpi_handle_warn(handle, "No _EJ0 support for device\n");
 571         else if (ACPI_FAILURE(status))
 572                 acpi_handle_warn(handle, "Eject failed (0x%x)\n", status);
 573 
 574         return status;
 575 }
 576 
 577 /**
 578  * acpi_evaluate_lck: Evaluate _LCK method to lock/unlock device
 579  * @handle: ACPI device handle
 580  * @lock: lock device if non-zero, otherwise unlock device
 581  *
 582  * Evaluate device's _LCK method if present to lock/unlock device
 583  */
 584 acpi_status acpi_evaluate_lck(acpi_handle handle, int lock)
 585 {
 586         acpi_status status;
 587 
 588         status = acpi_execute_simple_method(handle, "_LCK", !!lock);
 589         if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
 590                 if (lock)
 591                         acpi_handle_warn(handle,
 592                                 "Locking device failed (0x%x)\n", status);
 593                 else
 594                         acpi_handle_warn(handle,
 595                                 "Unlocking device failed (0x%x)\n", status);
 596         }
 597 
 598         return status;
 599 }
 600 
 601 /**
 602  * acpi_evaluate_dsm - evaluate device's _DSM method
 603  * @handle: ACPI device handle
 604  * @guid: GUID of requested functions, should be 16 bytes
 605  * @rev: revision number of requested function
 606  * @func: requested function number
 607  * @argv4: the function specific parameter
 608  *
 609  * Evaluate device's _DSM method with specified GUID, revision id and
 610  * function number. Caller needs to free the returned object.
 611  *
 612  * Though ACPI defines the fourth parameter for _DSM should be a package,
 613  * some old BIOSes do expect a buffer or an integer etc.
 614  */
 615 union acpi_object *
 616 acpi_evaluate_dsm(acpi_handle handle, const guid_t *guid, u64 rev, u64 func,
 617                   union acpi_object *argv4)
 618 {
 619         acpi_status ret;
 620         struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
 621         union acpi_object params[4];
 622         struct acpi_object_list input = {
 623                 .count = 4,
 624                 .pointer = params,
 625         };
 626 
 627         params[0].type = ACPI_TYPE_BUFFER;
 628         params[0].buffer.length = 16;
 629         params[0].buffer.pointer = (u8 *)guid;
 630         params[1].type = ACPI_TYPE_INTEGER;
 631         params[1].integer.value = rev;
 632         params[2].type = ACPI_TYPE_INTEGER;
 633         params[2].integer.value = func;
 634         if (argv4) {
 635                 params[3] = *argv4;
 636         } else {
 637                 params[3].type = ACPI_TYPE_PACKAGE;
 638                 params[3].package.count = 0;
 639                 params[3].package.elements = NULL;
 640         }
 641 
 642         ret = acpi_evaluate_object(handle, "_DSM", &input, &buf);
 643         if (ACPI_SUCCESS(ret))
 644                 return (union acpi_object *)buf.pointer;
 645 
 646         if (ret != AE_NOT_FOUND)
 647                 acpi_handle_warn(handle,
 648                                 "failed to evaluate _DSM (0x%x)\n", ret);
 649 
 650         return NULL;
 651 }
 652 EXPORT_SYMBOL(acpi_evaluate_dsm);
 653 
 654 /**
 655  * acpi_check_dsm - check if _DSM method supports requested functions.
 656  * @handle: ACPI device handle
 657  * @guid: GUID of requested functions, should be 16 bytes at least
 658  * @rev: revision number of requested functions
 659  * @funcs: bitmap of requested functions
 660  *
 661  * Evaluate device's _DSM method to check whether it supports requested
 662  * functions. Currently only support 64 functions at maximum, should be
 663  * enough for now.
 664  */
 665 bool acpi_check_dsm(acpi_handle handle, const guid_t *guid, u64 rev, u64 funcs)
 666 {
 667         int i;
 668         u64 mask = 0;
 669         union acpi_object *obj;
 670 
 671         if (funcs == 0)
 672                 return false;
 673 
 674         obj = acpi_evaluate_dsm(handle, guid, rev, 0, NULL);
 675         if (!obj)
 676                 return false;
 677 
 678         /* For compatibility, old BIOSes may return an integer */
 679         if (obj->type == ACPI_TYPE_INTEGER)
 680                 mask = obj->integer.value;
 681         else if (obj->type == ACPI_TYPE_BUFFER)
 682                 for (i = 0; i < obj->buffer.length && i < 8; i++)
 683                         mask |= (((u64)obj->buffer.pointer[i]) << (i * 8));
 684         ACPI_FREE(obj);
 685 
 686         /*
 687          * Bit 0 indicates whether there's support for any functions other than
 688          * function 0 for the specified GUID and revision.
 689          */
 690         if ((mask & 0x1) && (mask & funcs) == funcs)
 691                 return true;
 692 
 693         return false;
 694 }
 695 EXPORT_SYMBOL(acpi_check_dsm);
 696 
 697 /**
 698  * acpi_dev_found - Detect presence of a given ACPI device in the namespace.
 699  * @hid: Hardware ID of the device.
 700  *
 701  * Return %true if the device was present at the moment of invocation.
 702  * Note that if the device is pluggable, it may since have disappeared.
 703  *
 704  * For this function to work, acpi_bus_scan() must have been executed
 705  * which happens in the subsys_initcall() subsection. Hence, do not
 706  * call from a subsys_initcall() or earlier (use acpi_get_devices()
 707  * instead). Calling from module_init() is fine (which is synonymous
 708  * with device_initcall()).
 709  */
 710 bool acpi_dev_found(const char *hid)
 711 {
 712         struct acpi_device_bus_id *acpi_device_bus_id;
 713         bool found = false;
 714 
 715         mutex_lock(&acpi_device_lock);
 716         list_for_each_entry(acpi_device_bus_id, &acpi_bus_id_list, node)
 717                 if (!strcmp(acpi_device_bus_id->bus_id, hid)) {
 718                         found = true;
 719                         break;
 720                 }
 721         mutex_unlock(&acpi_device_lock);
 722 
 723         return found;
 724 }
 725 EXPORT_SYMBOL(acpi_dev_found);
 726 
 727 struct acpi_dev_match_info {
 728         struct acpi_device_id hid[2];
 729         const char *uid;
 730         s64 hrv;
 731 };
 732 
 733 static int acpi_dev_match_cb(struct device *dev, const void *data)
 734 {
 735         struct acpi_device *adev = to_acpi_device(dev);
 736         const struct acpi_dev_match_info *match = data;
 737         unsigned long long hrv;
 738         acpi_status status;
 739 
 740         if (acpi_match_device_ids(adev, match->hid))
 741                 return 0;
 742 
 743         if (match->uid && (!adev->pnp.unique_id ||
 744             strcmp(adev->pnp.unique_id, match->uid)))
 745                 return 0;
 746 
 747         if (match->hrv == -1)
 748                 return 1;
 749 
 750         status = acpi_evaluate_integer(adev->handle, "_HRV", NULL, &hrv);
 751         if (ACPI_FAILURE(status))
 752                 return 0;
 753 
 754         return hrv == match->hrv;
 755 }
 756 
 757 /**
 758  * acpi_dev_present - Detect that a given ACPI device is present
 759  * @hid: Hardware ID of the device.
 760  * @uid: Unique ID of the device, pass NULL to not check _UID
 761  * @hrv: Hardware Revision of the device, pass -1 to not check _HRV
 762  *
 763  * Return %true if a matching device was present at the moment of invocation.
 764  * Note that if the device is pluggable, it may since have disappeared.
 765  *
 766  * Note that unlike acpi_dev_found() this function checks the status
 767  * of the device. So for devices which are present in the dsdt, but
 768  * which are disabled (their _STA callback returns 0) this function
 769  * will return false.
 770  *
 771  * For this function to work, acpi_bus_scan() must have been executed
 772  * which happens in the subsys_initcall() subsection. Hence, do not
 773  * call from a subsys_initcall() or earlier (use acpi_get_devices()
 774  * instead). Calling from module_init() is fine (which is synonymous
 775  * with device_initcall()).
 776  */
 777 bool acpi_dev_present(const char *hid, const char *uid, s64 hrv)
 778 {
 779         struct acpi_dev_match_info match = {};
 780         struct device *dev;
 781 
 782         strlcpy(match.hid[0].id, hid, sizeof(match.hid[0].id));
 783         match.uid = uid;
 784         match.hrv = hrv;
 785 
 786         dev = bus_find_device(&acpi_bus_type, NULL, &match, acpi_dev_match_cb);
 787         put_device(dev);
 788         return !!dev;
 789 }
 790 EXPORT_SYMBOL(acpi_dev_present);
 791 
 792 /**
 793  * acpi_dev_get_first_match_dev - Return the first match of ACPI device
 794  * @hid: Hardware ID of the device.
 795  * @uid: Unique ID of the device, pass NULL to not check _UID
 796  * @hrv: Hardware Revision of the device, pass -1 to not check _HRV
 797  *
 798  * Return the first match of ACPI device if a matching device was present
 799  * at the moment of invocation, or NULL otherwise.
 800  *
 801  * The caller is responsible to call put_device() on the returned device.
 802  *
 803  * See additional information in acpi_dev_present() as well.
 804  */
 805 struct acpi_device *
 806 acpi_dev_get_first_match_dev(const char *hid, const char *uid, s64 hrv)
 807 {
 808         struct acpi_dev_match_info match = {};
 809         struct device *dev;
 810 
 811         strlcpy(match.hid[0].id, hid, sizeof(match.hid[0].id));
 812         match.uid = uid;
 813         match.hrv = hrv;
 814 
 815         dev = bus_find_device(&acpi_bus_type, NULL, &match, acpi_dev_match_cb);
 816         return dev ? to_acpi_device(dev) : NULL;
 817 }
 818 EXPORT_SYMBOL(acpi_dev_get_first_match_dev);
 819 
 820 /*
 821  * acpi_backlight= handling, this is done here rather then in video_detect.c
 822  * because __setup cannot be used in modules.
 823  */
 824 char acpi_video_backlight_string[16];
 825 EXPORT_SYMBOL(acpi_video_backlight_string);
 826 
 827 static int __init acpi_backlight(char *str)
 828 {
 829         strlcpy(acpi_video_backlight_string, str,
 830                 sizeof(acpi_video_backlight_string));
 831         return 1;
 832 }
 833 __setup("acpi_backlight=", acpi_backlight);
 834 
 835 /**
 836  * acpi_match_platform_list - Check if the system matches with a given list
 837  * @plat: pointer to acpi_platform_list table terminated by a NULL entry
 838  *
 839  * Return the matched index if the system is found in the platform list.
 840  * Otherwise, return a negative error code.
 841  */
 842 int acpi_match_platform_list(const struct acpi_platform_list *plat)
 843 {
 844         struct acpi_table_header hdr;
 845         int idx = 0;
 846 
 847         if (acpi_disabled)
 848                 return -ENODEV;
 849 
 850         for (; plat->oem_id[0]; plat++, idx++) {
 851                 if (ACPI_FAILURE(acpi_get_table_header(plat->table, 0, &hdr)))
 852                         continue;
 853 
 854                 if (strncmp(plat->oem_id, hdr.oem_id, ACPI_OEM_ID_SIZE))
 855                         continue;
 856 
 857                 if (strncmp(plat->oem_table_id, hdr.oem_table_id, ACPI_OEM_TABLE_ID_SIZE))
 858                         continue;
 859 
 860                 if ((plat->pred == all_versions) ||
 861                     (plat->pred == less_than_or_equal && hdr.oem_revision <= plat->oem_revision) ||
 862                     (plat->pred == greater_than_or_equal && hdr.oem_revision >= plat->oem_revision) ||
 863                     (plat->pred == equal && hdr.oem_revision == plat->oem_revision))
 864                         return idx;
 865         }
 866 
 867         return -ENODEV;
 868 }
 869 EXPORT_SYMBOL(acpi_match_platform_list);