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  *  You should have received a copy of the GNU General Public License along
  20  *  with this program; if not, write to the Free Software Foundation, Inc.,
  21  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  22  *
  23  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  24  */
  25
  26 #include <linux/kernel.h>
  27 #include <linux/module.h>
  28 #include <linux/slab.h>
  29 #include <linux/init.h>
  30 #include <linux/types.h>
  31 #include <linux/hardirq.h>
  32 #include <linux/acpi.h>
  33 #include <linux/dynamic_debug.h>
  34
  35 #include "internal.h"
  36
  37 #define _COMPONENT              ACPI_BUS_COMPONENT
  38 ACPI_MODULE_NAME("utils");
  39
  40 /* --------------------------------------------------------------------------
  41                             Object Evaluation Helpers
  42    -------------------------------------------------------------------------- */
  43 static void
  44 acpi_util_eval_error(acpi_handle h, acpi_string p, acpi_status s)
  45 {
  46 #ifdef ACPI_DEBUG_OUTPUT
  47         char prefix[80] = {'\0'};
  48         struct acpi_buffer buffer = {sizeof(prefix), prefix};
  49         acpi_get_name(h, ACPI_FULL_PATHNAME, &buffer);
  50         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Evaluate [%s.%s]: %s\n",
  51                 (char *) prefix, p, acpi_format_exception(s)));
  52 #else
  53         return;
  54 #endif
  55 }
  56
  57 acpi_status
  58 acpi_extract_package(union acpi_object *package,
  59                      struct acpi_buffer *format, struct acpi_buffer *buffer)
  60 {
  61         u32 size_required = 0;
  62         u32 tail_offset = 0;
  63         char *format_string = NULL;
  64         u32 format_count = 0;
  65         u32 i = 0;
  66         u8 *head = NULL;
  67         u8 *tail = NULL;
  68
  69
  70         if (!package || (package->type != ACPI_TYPE_PACKAGE)
  71             || (package->package.count < 1)) {
  72                 printk(KERN_WARNING PREFIX "Invalid package argument\n");
  73                 return AE_BAD_PARAMETER;
  74         }
  75
  76         if (!format || !format->pointer || (format->length < 1)) {
  77                 printk(KERN_WARNING PREFIX "Invalid format argument\n");
  78                 return AE_BAD_PARAMETER;
  79         }
  80
  81         if (!buffer) {
  82                 printk(KERN_WARNING PREFIX "Invalid buffer argument\n");
  83                 return AE_BAD_PARAMETER;
  84         }
  85
  86         format_count = (format->length / sizeof(char)) - 1;
  87         if (format_count > package->package.count) {
  88                 printk(KERN_WARNING PREFIX "Format specifies more objects [%d]"
  89                               " than exist in package [%d].\n",
  90                               format_count, package->package.count);
  91                 return AE_BAD_DATA;
  92         }
  93
  94         format_string = format->pointer;
  95
  96         /*
  97          * Calculate size_required.
  98          */
  99         for (i = 0; i < format_count; i++) {
 100
 101                 union acpi_object *element = &(package->package.elements[i]);
 102
 103                 switch (element->type) {
 104
 105                 case ACPI_TYPE_INTEGER:
 106                         switch (format_string[i]) {
 107                         case 'N':
 108                                 size_required += sizeof(u64);
 109                                 tail_offset += sizeof(u64);
 110                                 break;
 111                         case 'S':
 112                                 size_required +=
 113                                     sizeof(char *) + sizeof(u64) +
 114                                     sizeof(char);
 115                                 tail_offset += sizeof(char *);
 116                                 break;
 117                         default:
 118                                 printk(KERN_WARNING PREFIX "Invalid package element"
 119                                               " [%d]: got number, expecting"
 120                                               " [%c]\n",
 121                                               i, format_string[i]);
 122                                 return AE_BAD_DATA;
 123                                 break;
 124                         }
 125                         break;
 126
 127                 case ACPI_TYPE_STRING:
 128                 case ACPI_TYPE_BUFFER:
 129                         switch (format_string[i]) {
 130                         case 'S':
 131                                 size_required +=
 132                                     sizeof(char *) +
 133                                     (element->string.length * sizeof(char)) +
 134                                     sizeof(char);
 135                                 tail_offset += sizeof(char *);
 136                                 break;
 137                         case 'B':
 138                                 size_required +=
 139                                     sizeof(u8 *) +
 140                                     (element->buffer.length * sizeof(u8));
 141                                 tail_offset += sizeof(u8 *);
 142                                 break;
 143                         default:
 144                                 printk(KERN_WARNING PREFIX "Invalid package element"
 145                                               " [%d] got string/buffer,"
 146                                               " expecting [%c]\n",
 147                                               i, format_string[i]);
 148                                 return AE_BAD_DATA;
 149                                 break;
 150                         }
 151                         break;
 152                 case ACPI_TYPE_LOCAL_REFERENCE:
 153                         switch (format_string[i]) {
 154                         case 'R':
 155                                 size_required += sizeof(void *);
 156                                 tail_offset += sizeof(void *);
 157                                 break;
 158                         default:
 159                                 printk(KERN_WARNING PREFIX "Invalid package element"
 160                                               " [%d] got reference,"
 161                                               " expecting [%c]\n",
 162                                               i, format_string[i]);
 163                                 return AE_BAD_DATA;
 164                                 break;
 165                         }
 166                         break;
 167
 168                 case ACPI_TYPE_PACKAGE:
 169                 default:
 170                         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 171                                           "Found unsupported element at index=%d\n",
 172                                           i));
 173                         /* TBD: handle nested packages... */
 174                         return AE_SUPPORT;
 175                         break;
 176                 }
 177         }
 178
 179         /*
 180          * Validate output buffer.
 181          */
 182         if (buffer->length == ACPI_ALLOCATE_BUFFER) {
 183                 buffer->pointer = ACPI_ALLOCATE_ZEROED(size_required);
 184                 if (!buffer->pointer)
 185                         return AE_NO_MEMORY;
 186                 buffer->length = size_required;
 187         } else {
 188                 if (buffer->length < size_required) {
 189                         buffer->length = size_required;
 190                         return AE_BUFFER_OVERFLOW;
 191                 } else if (buffer->length != size_required ||
 192                            !buffer->pointer) {
 193                         return AE_BAD_PARAMETER;
 194                 }
 195         }
 196
 197         head = buffer->pointer;
 198         tail = buffer->pointer + tail_offset;
 199
 200         /*
 201          * Extract package data.
 202          */
 203         for (i = 0; i < format_count; i++) {
 204
 205                 u8 **pointer = NULL;
 206                 union acpi_object *element = &(package->package.elements[i]);
 207
 208                 if (!element) {
 209                         return AE_BAD_DATA;
 210                 }
 211
 212                 switch (element->type) {
 213
 214                 case ACPI_TYPE_INTEGER:
 215                         switch (format_string[i]) {
 216                         case 'N':
 217                                 *((u64 *) head) =
 218                                     element->integer.value;
 219                                 head += sizeof(u64);
 220                                 break;
 221                         case 'S':
 222                                 pointer = (u8 **) head;
 223                                 *pointer = tail;
 224                                 *((u64 *) tail) =
 225                                     element->integer.value;
 226                                 head += sizeof(u64 *);
 227                                 tail += sizeof(u64);
 228                                 /* NULL terminate string */
 229                                 *tail = (char)0;
 230                                 tail += sizeof(char);
 231                                 break;
 232                         default:
 233                                 /* Should never get here */
 234                                 break;
 235                         }
 236                         break;
 237
 238                 case ACPI_TYPE_STRING:
 239                 case ACPI_TYPE_BUFFER:
 240                         switch (format_string[i]) {
 241                         case 'S':
 242                                 pointer = (u8 **) head;
 243                                 *pointer = tail;
 244                                 memcpy(tail, element->string.pointer,
 245                                        element->string.length);
 246                                 head += sizeof(char *);
 247                                 tail += element->string.length * sizeof(char);
 248                                 /* NULL terminate string */
 249                                 *tail = (char)0;
 250                                 tail += sizeof(char);
 251                                 break;
 252                         case 'B':
 253                                 pointer = (u8 **) head;
 254                                 *pointer = tail;
 255                                 memcpy(tail, element->buffer.pointer,
 256                                        element->buffer.length);
 257                                 head += sizeof(u8 *);
 258                                 tail += element->buffer.length * sizeof(u8);
 259                                 break;
 260                         default:
 261                                 /* Should never get here */
 262                                 break;
 263                         }
 264                         break;
 265                 case ACPI_TYPE_LOCAL_REFERENCE:
 266                         switch (format_string[i]) {
 267                         case 'R':
 268                                 *(void **)head =
 269                                     (void *)element->reference.handle;
 270                                 head += sizeof(void *);
 271                                 break;
 272                         default:
 273                                 /* Should never get here */
 274                                 break;
 275                         }
 276                         break;
 277                 case ACPI_TYPE_PACKAGE:
 278                         /* TBD: handle nested packages... */
 279                 default:
 280                         /* Should never get here */
 281                         break;
 282                 }
 283         }
 284
 285         return AE_OK;
 286 }
 287
 288 EXPORT_SYMBOL(acpi_extract_package);
 289
 290 acpi_status
 291 acpi_evaluate_integer(acpi_handle handle,
 292                       acpi_string pathname,
 293                       struct acpi_object_list *arguments, unsigned long long *data)
 294 {
 295         acpi_status status = AE_OK;
 296         union acpi_object element;
 297         struct acpi_buffer buffer = { 0, NULL };
 298
 299         if (!data)
 300                 return AE_BAD_PARAMETER;
 301
 302         buffer.length = sizeof(union acpi_object);
 303         buffer.pointer = &element;
 304         status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
 305         if (ACPI_FAILURE(status)) {
 306                 acpi_util_eval_error(handle, pathname, status);
 307                 return status;
 308         }
 309
 310         if (element.type != ACPI_TYPE_INTEGER) {
 311                 acpi_util_eval_error(handle, pathname, AE_BAD_DATA);
 312                 return AE_BAD_DATA;
 313         }
 314
 315         *data = element.integer.value;
 316
 317         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Return value [%llu]\n", *data));
 318
 319         return AE_OK;
 320 }
 321
 322 EXPORT_SYMBOL(acpi_evaluate_integer);
 323
 324 acpi_status
 325 acpi_evaluate_reference(acpi_handle handle,
 326                         acpi_string pathname,
 327                         struct acpi_object_list *arguments,
 328                         struct acpi_handle_list *list)
 329 {
 330         acpi_status status = AE_OK;
 331         union acpi_object *package = NULL;
 332         union acpi_object *element = NULL;
 333         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 334         u32 i = 0;
 335
 336
 337         if (!list) {
 338                 return AE_BAD_PARAMETER;
 339         }
 340
 341         /* Evaluate object. */
 342
 343         status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
 344         if (ACPI_FAILURE(status))
 345                 goto end;
 346
 347         package = buffer.pointer;
 348
 349         if ((buffer.length == 0) || !package) {
 350                 printk(KERN_ERR PREFIX "No return object (len %X ptr %p)\n",
 351                             (unsigned)buffer.length, package);
 352                 status = AE_BAD_DATA;
 353                 acpi_util_eval_error(handle, pathname, status);
 354                 goto end;
 355         }
 356         if (package->type != ACPI_TYPE_PACKAGE) {
 357                 printk(KERN_ERR PREFIX "Expecting a [Package], found type %X\n",
 358                             package->type);
 359                 status = AE_BAD_DATA;
 360                 acpi_util_eval_error(handle, pathname, status);
 361                 goto end;
 362         }
 363         if (!package->package.count) {
 364                 printk(KERN_ERR PREFIX "[Package] has zero elements (%p)\n",
 365                             package);
 366                 status = AE_BAD_DATA;
 367                 acpi_util_eval_error(handle, pathname, status);
 368                 goto end;
 369         }
 370
 371         if (package->package.count > ACPI_MAX_HANDLES) {
 372                 return AE_NO_MEMORY;
 373         }
 374         list->count = package->package.count;
 375
 376         /* Extract package data. */
 377
 378         for (i = 0; i < list->count; i++) {
 379
 380                 element = &(package->package.elements[i]);
 381
 382                 if (element->type != ACPI_TYPE_LOCAL_REFERENCE) {
 383                         status = AE_BAD_DATA;
 384                         printk(KERN_ERR PREFIX
 385                                     "Expecting a [Reference] package element, found type %X\n",
 386                                     element->type);
 387                         acpi_util_eval_error(handle, pathname, status);
 388                         break;
 389                 }
 390
 391                 if (!element->reference.handle) {
 392                         printk(KERN_WARNING PREFIX "Invalid reference in"
 393                                " package %s\n", pathname);
 394                         status = AE_NULL_ENTRY;
 395                         break;
 396                 }
 397                 /* Get the  acpi_handle. */
 398
 399                 list->handles[i] = element->reference.handle;
 400                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found reference [%p]\n",
 401                                   list->handles[i]));
 402         }
 403
 404       end:
 405         if (ACPI_FAILURE(status)) {
 406                 list->count = 0;
 407                 //kfree(list->handles);
 408         }
 409
 410         kfree(buffer.pointer);
 411
 412         return status;
 413 }
 414
 415 EXPORT_SYMBOL(acpi_evaluate_reference);
 416
 417 acpi_status
 418 acpi_get_physical_device_location(acpi_handle handle, struct acpi_pld_info **pld)
 419 {
 420         acpi_status status;
 421         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 422         union acpi_object *output;
 423
 424         status = acpi_evaluate_object(handle, "_PLD", NULL, &buffer);
 425
 426         if (ACPI_FAILURE(status))
 427                 return status;
 428
 429         output = buffer.pointer;
 430
 431         if (!output || output->type != ACPI_TYPE_PACKAGE
 432             || !output->package.count
 433             || output->package.elements[0].type != ACPI_TYPE_BUFFER
 434             || output->package.elements[0].buffer.length < ACPI_PLD_REV1_BUFFER_SIZE) {
 435                 status = AE_TYPE;
 436                 goto out;
 437         }
 438
 439         status = acpi_decode_pld_buffer(
 440                         output->package.elements[0].buffer.pointer,
 441                         output->package.elements[0].buffer.length,
 442                         pld);
 443
 444 out:
 445         kfree(buffer.pointer);
 446         return status;
 447 }
 448 EXPORT_SYMBOL(acpi_get_physical_device_location);
 449
 450 /**
 451  * acpi_evaluate_ost: Evaluate _OST for hotplug operations
 452  * @handle: ACPI device handle
 453  * @source_event: source event code
 454  * @status_code: status code
 455  * @status_buf: optional detailed information (NULL if none)
 456  *
 457  * Evaluate _OST for hotplug operations. All ACPI hotplug handlers
 458  * must call this function when evaluating _OST for hotplug operations.
 459  * When the platform does not support _OST, this function has no effect.
 460  */
 461 acpi_status
 462 acpi_evaluate_ost(acpi_handle handle, u32 source_event, u32 status_code,
 463                   struct acpi_buffer *status_buf)
 464 {
 465         union acpi_object params[3] = {
 466                 {.type = ACPI_TYPE_INTEGER,},
 467                 {.type = ACPI_TYPE_INTEGER,},
 468                 {.type = ACPI_TYPE_BUFFER,}
 469         };
 470         struct acpi_object_list arg_list = {3, params};
 471
 472         params[0].integer.value = source_event;
 473         params[1].integer.value = status_code;
 474         if (status_buf != NULL) {
 475                 params[2].buffer.pointer = status_buf->pointer;
 476                 params[2].buffer.length = status_buf->length;
 477         } else {
 478                 params[2].buffer.pointer = NULL;
 479                 params[2].buffer.length = 0;
 480         }
 481
 482         return acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
 483 }
 484 EXPORT_SYMBOL(acpi_evaluate_ost);
 485
 486 /**
 487  * acpi_handle_path: Return the object path of handle
 488  *
 489  * Caller must free the returned buffer
 490  */
 491 static char *acpi_handle_path(acpi_handle handle)
 492 {
 493         struct acpi_buffer buffer = {
 494                 .length = ACPI_ALLOCATE_BUFFER,
 495                 .pointer = NULL
 496         };
 497
 498         if (in_interrupt() ||
 499             acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer) != AE_OK)
 500                 return NULL;
 501         return buffer.pointer;
 502 }
 503
 504 /**
 505  * acpi_handle_printk: Print message with ACPI prefix and object path
 506  *
 507  * This function is called through acpi_handle_<level> macros and prints
 508  * a message with ACPI prefix and object path.  This function acquires
 509  * the global namespace mutex to obtain an object path.  In interrupt
 510  * context, it shows the object path as <n/a>.
 511  */
 512 void
 513 acpi_handle_printk(const char *level, acpi_handle handle, const char *fmt, ...)
 514 {
 515         struct va_format vaf;
 516         va_list args;
 517         const char *path;
 518
 519         va_start(args, fmt);
 520         vaf.fmt = fmt;
 521         vaf.va = &args;
 522
 523         path = acpi_handle_path(handle);
 524         printk("%sACPI: %s: %pV", level, path ? path : "<n/a>" , &vaf);
 525
 526         va_end(args);
 527         kfree(path);
 528 }
 529 EXPORT_SYMBOL(acpi_handle_printk);
 530
 531 #if defined(CONFIG_DYNAMIC_DEBUG)
 532 /**
 533  * __acpi_handle_debug: pr_debug with ACPI prefix and object path
 534  *
 535  * This function is called through acpi_handle_debug macro and debug
 536  * prints a message with ACPI prefix and object path. This function
 537  * acquires the global namespace mutex to obtain an object path.  In
 538  * interrupt context, it shows the object path as <n/a>.
 539  */
 540 void
 541 __acpi_handle_debug(struct _ddebug *descriptor, acpi_handle handle,
 542                     const char *fmt, ...)
 543 {
 544         struct va_format vaf;
 545         va_list args;
 546         const char *path;
 547
 548         va_start(args, fmt);
 549         vaf.fmt = fmt;
 550         vaf.va = &args;
 551
 552         path = acpi_handle_path(handle);
 553         __dynamic_pr_debug(descriptor, "ACPI: %s: %pV", path ? path : "<n/a>", &vaf);
 554
 555         va_end(args);
 556         kfree(path);
 557 }
 558 EXPORT_SYMBOL(__acpi_handle_debug);
 559 #endif
 560
 561 /**
 562  * acpi_has_method: Check whether @handle has a method named @name
 563  * @handle: ACPI device handle
 564  * @name: name of object or method
 565  *
 566  * Check whether @handle has a method named @name.
 567  */
 568 bool acpi_has_method(acpi_handle handle, char *name)
 569 {
 570         acpi_handle tmp;
 571
 572         return ACPI_SUCCESS(acpi_get_handle(handle, name, &tmp));
 573 }
 574 EXPORT_SYMBOL(acpi_has_method);
 575
 576 acpi_status acpi_execute_simple_method(acpi_handle handle, char *method,
 577                                        u64 arg)
 578 {
 579         union acpi_object obj = { .type = ACPI_TYPE_INTEGER };
 580         struct acpi_object_list arg_list = { .count = 1, .pointer = &obj, };
 581
 582         obj.integer.value = arg;
 583
 584         return acpi_evaluate_object(handle, method, &arg_list, NULL);
 585 }
 586 EXPORT_SYMBOL(acpi_execute_simple_method);
 587
 588 /**
 589  * acpi_evaluate_ej0: Evaluate _EJ0 method for hotplug operations
 590  * @handle: ACPI device handle
 591  *
 592  * Evaluate device's _EJ0 method for hotplug operations.
 593  */
 594 acpi_status acpi_evaluate_ej0(acpi_handle handle)
 595 {
 596         acpi_status status;
 597
 598         status = acpi_execute_simple_method(handle, "_EJ0", 1);
 599         if (status == AE_NOT_FOUND)
 600                 acpi_handle_warn(handle, "No _EJ0 support for device\n");
 601         else if (ACPI_FAILURE(status))
 602                 acpi_handle_warn(handle, "Eject failed (0x%x)\n", status);
 603
 604         return status;
 605 }
 606
 607 /**
 608  * acpi_evaluate_lck: Evaluate _LCK method to lock/unlock device
 609  * @handle: ACPI device handle
 610  * @lock: lock device if non-zero, otherwise unlock device
 611  *
 612  * Evaluate device's _LCK method if present to lock/unlock device
 613  */
 614 acpi_status acpi_evaluate_lck(acpi_handle handle, int lock)
 615 {
 616         acpi_status status;
 617
 618         status = acpi_execute_simple_method(handle, "_LCK", !!lock);
 619         if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
 620                 if (lock)
 621                         acpi_handle_warn(handle,
 622                                 "Locking device failed (0x%x)\n", status);
 623                 else
 624                         acpi_handle_warn(handle,
 625                                 "Unlocking device failed (0x%x)\n", status);
 626         }
 627
 628         return status;
 629 }
 630
 631 /**
 632  * acpi_evaluate_dsm - evaluate device's _DSM method
 633  * @handle: ACPI device handle
 634  * @uuid: UUID of requested functions, should be 16 bytes
 635  * @rev: revision number of requested function
 636  * @func: requested function number
 637  * @argv4: the function specific parameter
 638  *
 639  * Evaluate device's _DSM method with specified UUID, revision id and
 640  * function number. Caller needs to free the returned object.
 641  *
 642  * Though ACPI defines the fourth parameter for _DSM should be a package,
 643  * some old BIOSes do expect a buffer or an integer etc.
 644  */
 645 union acpi_object *
 646 acpi_evaluate_dsm(acpi_handle handle, const u8 *uuid, int rev, int func,
 647                   union acpi_object *argv4)
 648 {
 649         acpi_status ret;
 650         struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
 651         union acpi_object params[4];
 652         struct acpi_object_list input = {
 653                 .count = 4,
 654                 .pointer = params,
 655         };
 656
 657         params[0].type = ACPI_TYPE_BUFFER;
 658         params[0].buffer.length = 16;
 659         params[0].buffer.pointer = (char *)uuid;
 660         params[1].type = ACPI_TYPE_INTEGER;
 661         params[1].integer.value = rev;
 662         params[2].type = ACPI_TYPE_INTEGER;
 663         params[2].integer.value = func;
 664         if (argv4) {
 665                 params[3] = *argv4;
 666         } else {
 667                 params[3].type = ACPI_TYPE_PACKAGE;
 668                 params[3].package.count = 0;
 669                 params[3].package.elements = NULL;
 670         }
 671
 672         ret = acpi_evaluate_object(handle, "_DSM", &input, &buf);
 673         if (ACPI_SUCCESS(ret))
 674                 return (union acpi_object *)buf.pointer;
 675
 676         if (ret != AE_NOT_FOUND)
 677                 acpi_handle_warn(handle,
 678                                 "failed to evaluate _DSM (0x%x)\n", ret);
 679
 680         return NULL;
 681 }
 682 EXPORT_SYMBOL(acpi_evaluate_dsm);
 683
 684 /**
 685  * acpi_check_dsm - check if _DSM method supports requested functions.
 686  * @handle: ACPI device handle
 687  * @uuid: UUID of requested functions, should be 16 bytes at least
 688  * @rev: revision number of requested functions
 689  * @funcs: bitmap of requested functions
 690  *
 691  * Evaluate device's _DSM method to check whether it supports requested
 692  * functions. Currently only support 64 functions at maximum, should be
 693  * enough for now.
 694  */
 695 bool acpi_check_dsm(acpi_handle handle, const u8 *uuid, int rev, u64 funcs)
 696 {
 697         int i;
 698         u64 mask = 0;
 699         union acpi_object *obj;
 700
 701         if (funcs == 0)
 702                 return false;
 703
 704         obj = acpi_evaluate_dsm(handle, uuid, rev, 0, NULL);
 705         if (!obj)
 706                 return false;
 707
 708         /* For compatibility, old BIOSes may return an integer */
 709         if (obj->type == ACPI_TYPE_INTEGER)
 710                 mask = obj->integer.value;
 711         else if (obj->type == ACPI_TYPE_BUFFER)
 712                 for (i = 0; i < obj->buffer.length && i < 8; i++)
 713                         mask |= (((u8)obj->buffer.pointer[i]) << (i * 8));
 714         ACPI_FREE(obj);
 715
 716         /*
 717          * Bit 0 indicates whether there's support for any functions other than
 718          * function 0 for the specified UUID and revision.
 719          */
 720         if ((mask & 0x1) && (mask & funcs) == funcs)
 721                 return true;
 722
 723         return false;
 724 }
 725 EXPORT_SYMBOL(acpi_check_dsm);