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
 153                 case ACPI_TYPE_PACKAGE:
 154                 default:
 155                         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 156                                           "Found unsupported element at index=%d\n",
 157                                           i));
 158                         /* TBD: handle nested packages... */
 159                         return AE_SUPPORT;
 160                         break;
 161                 }
 162         }
 163
 164         /*
 165          * Validate output buffer.
 166          */
 167         if (buffer->length == ACPI_ALLOCATE_BUFFER) {
 168                 buffer->pointer = ACPI_ALLOCATE_ZEROED(size_required);
 169                 if (!buffer->pointer)
 170                         return AE_NO_MEMORY;
 171                 buffer->length = size_required;
 172         } else {
 173                 if (buffer->length < size_required) {
 174                         buffer->length = size_required;
 175                         return AE_BUFFER_OVERFLOW;
 176                 } else if (buffer->length != size_required ||
 177                            !buffer->pointer) {
 178                         return AE_BAD_PARAMETER;
 179                 }
 180         }
 181
 182         head = buffer->pointer;
 183         tail = buffer->pointer + tail_offset;
 184
 185         /*
 186          * Extract package data.
 187          */
 188         for (i = 0; i < format_count; i++) {
 189
 190                 u8 **pointer = NULL;
 191                 union acpi_object *element = &(package->package.elements[i]);
 192
 193                 if (!element) {
 194                         return AE_BAD_DATA;
 195                 }
 196
 197                 switch (element->type) {
 198
 199                 case ACPI_TYPE_INTEGER:
 200                         switch (format_string[i]) {
 201                         case 'N':
 202                                 *((u64 *) head) =
 203                                     element->integer.value;
 204                                 head += sizeof(u64);
 205                                 break;
 206                         case 'S':
 207                                 pointer = (u8 **) head;
 208                                 *pointer = tail;
 209                                 *((u64 *) tail) =
 210                                     element->integer.value;
 211                                 head += sizeof(u64 *);
 212                                 tail += sizeof(u64);
 213                                 /* NULL terminate string */
 214                                 *tail = (char)0;
 215                                 tail += sizeof(char);
 216                                 break;
 217                         default:
 218                                 /* Should never get here */
 219                                 break;
 220                         }
 221                         break;
 222
 223                 case ACPI_TYPE_STRING:
 224                 case ACPI_TYPE_BUFFER:
 225                         switch (format_string[i]) {
 226                         case 'S':
 227                                 pointer = (u8 **) head;
 228                                 *pointer = tail;
 229                                 memcpy(tail, element->string.pointer,
 230                                        element->string.length);
 231                                 head += sizeof(char *);
 232                                 tail += element->string.length * sizeof(char);
 233                                 /* NULL terminate string */
 234                                 *tail = (char)0;
 235                                 tail += sizeof(char);
 236                                 break;
 237                         case 'B':
 238                                 pointer = (u8 **) head;
 239                                 *pointer = tail;
 240                                 memcpy(tail, element->buffer.pointer,
 241                                        element->buffer.length);
 242                                 head += sizeof(u8 *);
 243                                 tail += element->buffer.length * sizeof(u8);
 244                                 break;
 245                         default:
 246                                 /* Should never get here */
 247                                 break;
 248                         }
 249                         break;
 250
 251                 case ACPI_TYPE_PACKAGE:
 252                         /* TBD: handle nested packages... */
 253                 default:
 254                         /* Should never get here */
 255                         break;
 256                 }
 257         }
 258
 259         return AE_OK;
 260 }
 261
 262 EXPORT_SYMBOL(acpi_extract_package);
 263
 264 acpi_status
 265 acpi_evaluate_integer(acpi_handle handle,
 266                       acpi_string pathname,
 267                       struct acpi_object_list *arguments, unsigned long long *data)
 268 {
 269         acpi_status status = AE_OK;
 270         union acpi_object element;
 271         struct acpi_buffer buffer = { 0, NULL };
 272
 273         if (!data)
 274                 return AE_BAD_PARAMETER;
 275
 276         buffer.length = sizeof(union acpi_object);
 277         buffer.pointer = &element;
 278         status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
 279         if (ACPI_FAILURE(status)) {
 280                 acpi_util_eval_error(handle, pathname, status);
 281                 return status;
 282         }
 283
 284         if (element.type != ACPI_TYPE_INTEGER) {
 285                 acpi_util_eval_error(handle, pathname, AE_BAD_DATA);
 286                 return AE_BAD_DATA;
 287         }
 288
 289         *data = element.integer.value;
 290
 291         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Return value [%llu]\n", *data));
 292
 293         return AE_OK;
 294 }
 295
 296 EXPORT_SYMBOL(acpi_evaluate_integer);
 297
 298 acpi_status
 299 acpi_evaluate_reference(acpi_handle handle,
 300                         acpi_string pathname,
 301                         struct acpi_object_list *arguments,
 302                         struct acpi_handle_list *list)
 303 {
 304         acpi_status status = AE_OK;
 305         union acpi_object *package = NULL;
 306         union acpi_object *element = NULL;
 307         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 308         u32 i = 0;
 309
 310
 311         if (!list) {
 312                 return AE_BAD_PARAMETER;
 313         }
 314
 315         /* Evaluate object. */
 316
 317         status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
 318         if (ACPI_FAILURE(status))
 319                 goto end;
 320
 321         package = buffer.pointer;
 322
 323         if ((buffer.length == 0) || !package) {
 324                 printk(KERN_ERR PREFIX "No return object (len %X ptr %p)\n",
 325                             (unsigned)buffer.length, package);
 326                 status = AE_BAD_DATA;
 327                 acpi_util_eval_error(handle, pathname, status);
 328                 goto end;
 329         }
 330         if (package->type != ACPI_TYPE_PACKAGE) {
 331                 printk(KERN_ERR PREFIX "Expecting a [Package], found type %X\n",
 332                             package->type);
 333                 status = AE_BAD_DATA;
 334                 acpi_util_eval_error(handle, pathname, status);
 335                 goto end;
 336         }
 337         if (!package->package.count) {
 338                 printk(KERN_ERR PREFIX "[Package] has zero elements (%p)\n",
 339                             package);
 340                 status = AE_BAD_DATA;
 341                 acpi_util_eval_error(handle, pathname, status);
 342                 goto end;
 343         }
 344
 345         if (package->package.count > ACPI_MAX_HANDLES) {
 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                         printk(KERN_ERR PREFIX
 359                                     "Expecting a [Reference] package element, found type %X\n",
 360                                     element->type);
 361                         acpi_util_eval_error(handle, pathname, status);
 362                         break;
 363                 }
 364
 365                 if (!element->reference.handle) {
 366                         printk(KERN_WARNING PREFIX "Invalid reference in"
 367                                " package %s\n", pathname);
 368                         status = AE_NULL_ENTRY;
 369                         break;
 370                 }
 371                 /* Get the  acpi_handle. */
 372
 373                 list->handles[i] = element->reference.handle;
 374                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found reference [%p]\n",
 375                                   list->handles[i]));
 376         }
 377
 378       end:
 379         if (ACPI_FAILURE(status)) {
 380                 list->count = 0;
 381                 //kfree(list->handles);
 382         }
 383
 384         kfree(buffer.pointer);
 385
 386         return status;
 387 }
 388
 389 EXPORT_SYMBOL(acpi_evaluate_reference);
 390
 391 acpi_status
 392 acpi_get_physical_device_location(acpi_handle handle, struct acpi_pld_info **pld)
 393 {
 394         acpi_status status;
 395         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 396         union acpi_object *output;
 397
 398         status = acpi_evaluate_object(handle, "_PLD", NULL, &buffer);
 399
 400         if (ACPI_FAILURE(status))
 401                 return status;
 402
 403         output = buffer.pointer;
 404
 405         if (!output || output->type != ACPI_TYPE_PACKAGE
 406             || !output->package.count
 407             || output->package.elements[0].type != ACPI_TYPE_BUFFER
 408             || output->package.elements[0].buffer.length < ACPI_PLD_REV1_BUFFER_SIZE) {
 409                 status = AE_TYPE;
 410                 goto out;
 411         }
 412
 413         status = acpi_decode_pld_buffer(
 414                         output->package.elements[0].buffer.pointer,
 415                         output->package.elements[0].buffer.length,
 416                         pld);
 417
 418 out:
 419         kfree(buffer.pointer);
 420         return status;
 421 }
 422 EXPORT_SYMBOL(acpi_get_physical_device_location);
 423
 424 /**
 425  * acpi_evaluate_ost: Evaluate _OST for hotplug operations
 426  * @handle: ACPI device handle
 427  * @source_event: source event code
 428  * @status_code: status code
 429  * @status_buf: optional detailed information (NULL if none)
 430  *
 431  * Evaluate _OST for hotplug operations. All ACPI hotplug handlers
 432  * must call this function when evaluating _OST for hotplug operations.
 433  * When the platform does not support _OST, this function has no effect.
 434  */
 435 acpi_status
 436 acpi_evaluate_ost(acpi_handle handle, u32 source_event, u32 status_code,
 437                   struct acpi_buffer *status_buf)
 438 {
 439         union acpi_object params[3] = {
 440                 {.type = ACPI_TYPE_INTEGER,},
 441                 {.type = ACPI_TYPE_INTEGER,},
 442                 {.type = ACPI_TYPE_BUFFER,}
 443         };
 444         struct acpi_object_list arg_list = {3, params};
 445
 446         params[0].integer.value = source_event;
 447         params[1].integer.value = status_code;
 448         if (status_buf != NULL) {
 449                 params[2].buffer.pointer = status_buf->pointer;
 450                 params[2].buffer.length = status_buf->length;
 451         } else {
 452                 params[2].buffer.pointer = NULL;
 453                 params[2].buffer.length = 0;
 454         }
 455
 456         return acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
 457 }
 458 EXPORT_SYMBOL(acpi_evaluate_ost);
 459
 460 /**
 461  * acpi_handle_path: Return the object path of handle
 462  *
 463  * Caller must free the returned buffer
 464  */
 465 static char *acpi_handle_path(acpi_handle handle)
 466 {
 467         struct acpi_buffer buffer = {
 468                 .length = ACPI_ALLOCATE_BUFFER,
 469                 .pointer = NULL
 470         };
 471
 472         if (in_interrupt() ||
 473             acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer) != AE_OK)
 474                 return NULL;
 475         return buffer.pointer;
 476 }
 477
 478 /**
 479  * acpi_handle_printk: Print message with ACPI prefix and object path
 480  *
 481  * This function is called through acpi_handle_<level> macros and prints
 482  * a message with ACPI prefix and object path.  This function acquires
 483  * the global namespace mutex to obtain an object path.  In interrupt
 484  * context, it shows the object path as <n/a>.
 485  */
 486 void
 487 acpi_handle_printk(const char *level, acpi_handle handle, const char *fmt, ...)
 488 {
 489         struct va_format vaf;
 490         va_list args;
 491         const char *path;
 492
 493         va_start(args, fmt);
 494         vaf.fmt = fmt;
 495         vaf.va = &args;
 496
 497         path = acpi_handle_path(handle);
 498         printk("%sACPI: %s: %pV", level, path ? path : "<n/a>" , &vaf);
 499
 500         va_end(args);
 501         kfree(path);
 502 }
 503 EXPORT_SYMBOL(acpi_handle_printk);
 504
 505 #if defined(CONFIG_DYNAMIC_DEBUG)
 506 /**
 507  * __acpi_handle_debug: pr_debug with ACPI prefix and object path
 508  *
 509  * This function is called through acpi_handle_debug macro and debug
 510  * prints a message with ACPI prefix and object path. This function
 511  * acquires the global namespace mutex to obtain an object path.  In
 512  * interrupt context, it shows the object path as <n/a>.
 513  */
 514 void
 515 __acpi_handle_debug(struct _ddebug *descriptor, acpi_handle handle,
 516                     const char *fmt, ...)
 517 {
 518         struct va_format vaf;
 519         va_list args;
 520         const char *path;
 521
 522         va_start(args, fmt);
 523         vaf.fmt = fmt;
 524         vaf.va = &args;
 525
 526         path = acpi_handle_path(handle);
 527         __dynamic_pr_debug(descriptor, "ACPI: %s: %pV", path ? path : "<n/a>", &vaf);
 528
 529         va_end(args);
 530         kfree(path);
 531 }
 532 EXPORT_SYMBOL(__acpi_handle_debug);
 533 #endif
 534
 535 /**
 536  * acpi_has_method: Check whether @handle has a method named @name
 537  * @handle: ACPI device handle
 538  * @name: name of object or method
 539  *
 540  * Check whether @handle has a method named @name.
 541  */
 542 bool acpi_has_method(acpi_handle handle, char *name)
 543 {
 544         acpi_handle tmp;
 545
 546         return ACPI_SUCCESS(acpi_get_handle(handle, name, &tmp));
 547 }
 548 EXPORT_SYMBOL(acpi_has_method);
 549
 550 acpi_status acpi_execute_simple_method(acpi_handle handle, char *method,
 551                                        u64 arg)
 552 {
 553         union acpi_object obj = { .type = ACPI_TYPE_INTEGER };
 554         struct acpi_object_list arg_list = { .count = 1, .pointer = &obj, };
 555
 556         obj.integer.value = arg;
 557
 558         return acpi_evaluate_object(handle, method, &arg_list, NULL);
 559 }
 560 EXPORT_SYMBOL(acpi_execute_simple_method);
 561
 562 /**
 563  * acpi_evaluate_ej0: Evaluate _EJ0 method for hotplug operations
 564  * @handle: ACPI device handle
 565  *
 566  * Evaluate device's _EJ0 method for hotplug operations.
 567  */
 568 acpi_status acpi_evaluate_ej0(acpi_handle handle)
 569 {
 570         acpi_status status;
 571
 572         status = acpi_execute_simple_method(handle, "_EJ0", 1);
 573         if (status == AE_NOT_FOUND)
 574                 acpi_handle_warn(handle, "No _EJ0 support for device\n");
 575         else if (ACPI_FAILURE(status))
 576                 acpi_handle_warn(handle, "Eject failed (0x%x)\n", status);
 577
 578         return status;
 579 }
 580
 581 /**
 582  * acpi_evaluate_lck: Evaluate _LCK method to lock/unlock device
 583  * @handle: ACPI device handle
 584  * @lock: lock device if non-zero, otherwise unlock device
 585  *
 586  * Evaluate device's _LCK method if present to lock/unlock device
 587  */
 588 acpi_status acpi_evaluate_lck(acpi_handle handle, int lock)
 589 {
 590         acpi_status status;
 591
 592         status = acpi_execute_simple_method(handle, "_LCK", !!lock);
 593         if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
 594                 if (lock)
 595                         acpi_handle_warn(handle,
 596                                 "Locking device failed (0x%x)\n", status);
 597                 else
 598                         acpi_handle_warn(handle,
 599                                 "Unlocking device failed (0x%x)\n", status);
 600         }
 601
 602         return status;
 603 }
 604
 605 /**
 606  * acpi_evaluate_dsm - evaluate device's _DSM method
 607  * @handle: ACPI device handle
 608  * @uuid: UUID of requested functions, should be 16 bytes
 609  * @rev: revision number of requested function
 610  * @func: requested function number
 611  * @argv4: the function specific parameter
 612  *
 613  * Evaluate device's _DSM method with specified UUID, revision id and
 614  * function number. Caller needs to free the returned object.
 615  *
 616  * Though ACPI defines the fourth parameter for _DSM should be a package,
 617  * some old BIOSes do expect a buffer or an integer etc.
 618  */
 619 union acpi_object *
 620 acpi_evaluate_dsm(acpi_handle handle, const u8 *uuid, int rev, int func,
 621                   union acpi_object *argv4)
 622 {
 623         acpi_status ret;
 624         struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
 625         union acpi_object params[4];
 626         struct acpi_object_list input = {
 627                 .count = 4,
 628                 .pointer = params,
 629         };
 630
 631         params[0].type = ACPI_TYPE_BUFFER;
 632         params[0].buffer.length = 16;
 633         params[0].buffer.pointer = (char *)uuid;
 634         params[1].type = ACPI_TYPE_INTEGER;
 635         params[1].integer.value = rev;
 636         params[2].type = ACPI_TYPE_INTEGER;
 637         params[2].integer.value = func;
 638         if (argv4) {
 639                 params[3] = *argv4;
 640         } else {
 641                 params[3].type = ACPI_TYPE_PACKAGE;
 642                 params[3].package.count = 0;
 643                 params[3].package.elements = NULL;
 644         }
 645
 646         ret = acpi_evaluate_object(handle, "_DSM", &input, &buf);
 647         if (ACPI_SUCCESS(ret))
 648                 return (union acpi_object *)buf.pointer;
 649
 650         if (ret != AE_NOT_FOUND)
 651                 acpi_handle_warn(handle,
 652                                 "failed to evaluate _DSM (0x%x)\n", ret);
 653
 654         return NULL;
 655 }
 656 EXPORT_SYMBOL(acpi_evaluate_dsm);
 657
 658 /**
 659  * acpi_check_dsm - check if _DSM method supports requested functions.
 660  * @handle: ACPI device handle
 661  * @uuid: UUID of requested functions, should be 16 bytes at least
 662  * @rev: revision number of requested functions
 663  * @funcs: bitmap of requested functions
 664  *
 665  * Evaluate device's _DSM method to check whether it supports requested
 666  * functions. Currently only support 64 functions at maximum, should be
 667  * enough for now.
 668  */
 669 bool acpi_check_dsm(acpi_handle handle, const u8 *uuid, int rev, u64 funcs)
 670 {
 671         int i;
 672         u64 mask = 0;
 673         union acpi_object *obj;
 674
 675         if (funcs == 0)
 676                 return false;
 677
 678         obj = acpi_evaluate_dsm(handle, uuid, rev, 0, NULL);
 679         if (!obj)
 680                 return false;
 681
 682         /* For compatibility, old BIOSes may return an integer */
 683         if (obj->type == ACPI_TYPE_INTEGER)
 684                 mask = obj->integer.value;
 685         else if (obj->type == ACPI_TYPE_BUFFER)
 686                 for (i = 0; i < obj->buffer.length && i < 8; i++)
 687                         mask |= (((u8)obj->buffer.pointer[i]) << (i * 8));
 688         ACPI_FREE(obj);
 689
 690         /*
 691          * Bit 0 indicates whether there's support for any functions other than
 692          * function 0 for the specified UUID and revision.
 693          */
 694         if ((mask & 0x1) && (mask & funcs) == funcs)
 695                 return true;
 696
 697         return false;
 698 }
 699 EXPORT_SYMBOL(acpi_check_dsm);