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(size_required);
 169                 if (!buffer->pointer)
 170                         return AE_NO_MEMORY;
 171                 buffer->length = size_required;
 172                 memset(buffer->pointer, 0, size_required);
 173         } else {
 174                 if (buffer->length < size_required) {
 175                         buffer->length = size_required;
 176                         return AE_BUFFER_OVERFLOW;
 177                 } else if (buffer->length != size_required ||
 178                            !buffer->pointer) {
 179                         return AE_BAD_PARAMETER;
 180                 }
 181         }
 182
 183         head = buffer->pointer;
 184         tail = buffer->pointer + tail_offset;
 185
 186         /*
 187          * Extract package data.
 188          */
 189         for (i = 0; i < format_count; i++) {
 190
 191                 u8 **pointer = NULL;
 192                 union acpi_object *element = &(package->package.elements[i]);
 193
 194                 if (!element) {
 195                         return AE_BAD_DATA;
 196                 }
 197
 198                 switch (element->type) {
 199
 200                 case ACPI_TYPE_INTEGER:
 201                         switch (format_string[i]) {
 202                         case 'N':
 203                                 *((u64 *) head) =
 204                                     element->integer.value;
 205                                 head += sizeof(u64);
 206                                 break;
 207                         case 'S':
 208                                 pointer = (u8 **) head;
 209                                 *pointer = tail;
 210                                 *((u64 *) tail) =
 211                                     element->integer.value;
 212                                 head += sizeof(u64 *);
 213                                 tail += sizeof(u64);
 214                                 /* NULL terminate string */
 215                                 *tail = (char)0;
 216                                 tail += sizeof(char);
 217                                 break;
 218                         default:
 219                                 /* Should never get here */
 220                                 break;
 221                         }
 222                         break;
 223
 224                 case ACPI_TYPE_STRING:
 225                 case ACPI_TYPE_BUFFER:
 226                         switch (format_string[i]) {
 227                         case 'S':
 228                                 pointer = (u8 **) head;
 229                                 *pointer = tail;
 230                                 memcpy(tail, element->string.pointer,
 231                                        element->string.length);
 232                                 head += sizeof(char *);
 233                                 tail += element->string.length * sizeof(char);
 234                                 /* NULL terminate string */
 235                                 *tail = (char)0;
 236                                 tail += sizeof(char);
 237                                 break;
 238                         case 'B':
 239                                 pointer = (u8 **) head;
 240                                 *pointer = tail;
 241                                 memcpy(tail, element->buffer.pointer,
 242                                        element->buffer.length);
 243                                 head += sizeof(u8 *);
 244                                 tail += element->buffer.length * sizeof(u8);
 245                                 break;
 246                         default:
 247                                 /* Should never get here */
 248                                 break;
 249                         }
 250                         break;
 251
 252                 case ACPI_TYPE_PACKAGE:
 253                         /* TBD: handle nested packages... */
 254                 default:
 255                         /* Should never get here */
 256                         break;
 257                 }
 258         }
 259
 260         return AE_OK;
 261 }
 262
 263 EXPORT_SYMBOL(acpi_extract_package);
 264
 265 acpi_status
 266 acpi_evaluate_integer(acpi_handle handle,
 267                       acpi_string pathname,
 268                       struct acpi_object_list *arguments, unsigned long long *data)
 269 {
 270         acpi_status status = AE_OK;
 271         union acpi_object element;
 272         struct acpi_buffer buffer = { 0, NULL };
 273
 274         if (!data)
 275                 return AE_BAD_PARAMETER;
 276
 277         buffer.length = sizeof(union acpi_object);
 278         buffer.pointer = &element;
 279         status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
 280         if (ACPI_FAILURE(status)) {
 281                 acpi_util_eval_error(handle, pathname, status);
 282                 return status;
 283         }
 284
 285         if (element.type != ACPI_TYPE_INTEGER) {
 286                 acpi_util_eval_error(handle, pathname, AE_BAD_DATA);
 287                 return AE_BAD_DATA;
 288         }
 289
 290         *data = element.integer.value;
 291
 292         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Return value [%llu]\n", *data));
 293
 294         return AE_OK;
 295 }
 296
 297 EXPORT_SYMBOL(acpi_evaluate_integer);
 298
 299 acpi_status
 300 acpi_evaluate_reference(acpi_handle handle,
 301                         acpi_string pathname,
 302                         struct acpi_object_list *arguments,
 303                         struct acpi_handle_list *list)
 304 {
 305         acpi_status status = AE_OK;
 306         union acpi_object *package = NULL;
 307         union acpi_object *element = NULL;
 308         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 309         u32 i = 0;
 310
 311
 312         if (!list) {
 313                 return AE_BAD_PARAMETER;
 314         }
 315
 316         /* Evaluate object. */
 317
 318         status = acpi_evaluate_object(handle, pathname, arguments, &buffer);
 319         if (ACPI_FAILURE(status))
 320                 goto end;
 321
 322         package = buffer.pointer;
 323
 324         if ((buffer.length == 0) || !package) {
 325                 printk(KERN_ERR PREFIX "No return object (len %X ptr %p)\n",
 326                             (unsigned)buffer.length, package);
 327                 status = AE_BAD_DATA;
 328                 acpi_util_eval_error(handle, pathname, status);
 329                 goto end;
 330         }
 331         if (package->type != ACPI_TYPE_PACKAGE) {
 332                 printk(KERN_ERR PREFIX "Expecting a [Package], found type %X\n",
 333                             package->type);
 334                 status = AE_BAD_DATA;
 335                 acpi_util_eval_error(handle, pathname, status);
 336                 goto end;
 337         }
 338         if (!package->package.count) {
 339                 printk(KERN_ERR PREFIX "[Package] has zero elements (%p)\n",
 340                             package);
 341                 status = AE_BAD_DATA;
 342                 acpi_util_eval_error(handle, pathname, status);
 343                 goto end;
 344         }
 345
 346         if (package->package.count > ACPI_MAX_HANDLES) {
 347                 return AE_NO_MEMORY;
 348         }
 349         list->count = package->package.count;
 350
 351         /* Extract package data. */
 352
 353         for (i = 0; i < list->count; i++) {
 354
 355                 element = &(package->package.elements[i]);
 356
 357                 if (element->type != ACPI_TYPE_LOCAL_REFERENCE) {
 358                         status = AE_BAD_DATA;
 359                         printk(KERN_ERR PREFIX
 360                                     "Expecting a [Reference] package element, found type %X\n",
 361                                     element->type);
 362                         acpi_util_eval_error(handle, pathname, status);
 363                         break;
 364                 }
 365
 366                 if (!element->reference.handle) {
 367                         printk(KERN_WARNING PREFIX "Invalid reference in"
 368                                " package %s\n", pathname);
 369                         status = AE_NULL_ENTRY;
 370                         break;
 371                 }
 372                 /* Get the  acpi_handle. */
 373
 374                 list->handles[i] = element->reference.handle;
 375                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found reference [%p]\n",
 376                                   list->handles[i]));
 377         }
 378
 379       end:
 380         if (ACPI_FAILURE(status)) {
 381                 list->count = 0;
 382                 //kfree(list->handles);
 383         }
 384
 385         kfree(buffer.pointer);
 386
 387         return status;
 388 }
 389
 390 EXPORT_SYMBOL(acpi_evaluate_reference);
 391
 392 acpi_status
 393 acpi_get_physical_device_location(acpi_handle handle, struct acpi_pld_info **pld)
 394 {
 395         acpi_status status;
 396         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 397         union acpi_object *output;
 398
 399         status = acpi_evaluate_object(handle, "_PLD", NULL, &buffer);
 400
 401         if (ACPI_FAILURE(status))
 402                 return status;
 403
 404         output = buffer.pointer;
 405
 406         if (!output || output->type != ACPI_TYPE_PACKAGE
 407             || !output->package.count
 408             || output->package.elements[0].type != ACPI_TYPE_BUFFER
 409             || output->package.elements[0].buffer.length < ACPI_PLD_REV1_BUFFER_SIZE) {
 410                 status = AE_TYPE;
 411                 goto out;
 412         }
 413
 414         status = acpi_decode_pld_buffer(
 415                         output->package.elements[0].buffer.pointer,
 416                         output->package.elements[0].buffer.length,
 417                         pld);
 418
 419 out:
 420         kfree(buffer.pointer);
 421         return status;
 422 }
 423 EXPORT_SYMBOL(acpi_get_physical_device_location);
 424
 425 /**
 426  * acpi_evaluate_hotplug_ost: Evaluate _OST for hotplug operations
 427  * @handle: ACPI device handle
 428  * @source_event: source event code
 429  * @status_code: status code
 430  * @status_buf: optional detailed information (NULL if none)
 431  *
 432  * Evaluate _OST for hotplug operations. All ACPI hotplug handlers
 433  * must call this function when evaluating _OST for hotplug operations.
 434  * When the platform does not support _OST, this function has no effect.
 435  */
 436 acpi_status
 437 acpi_evaluate_hotplug_ost(acpi_handle handle, u32 source_event,
 438                 u32 status_code, struct acpi_buffer *status_buf)
 439 {
 440 #ifdef ACPI_HOTPLUG_OST
 441         union acpi_object params[3] = {
 442                 {.type = ACPI_TYPE_INTEGER,},
 443                 {.type = ACPI_TYPE_INTEGER,},
 444                 {.type = ACPI_TYPE_BUFFER,}
 445         };
 446         struct acpi_object_list arg_list = {3, params};
 447         acpi_status status;
 448
 449         params[0].integer.value = source_event;
 450         params[1].integer.value = status_code;
 451         if (status_buf != NULL) {
 452                 params[2].buffer.pointer = status_buf->pointer;
 453                 params[2].buffer.length = status_buf->length;
 454         } else {
 455                 params[2].buffer.pointer = NULL;
 456                 params[2].buffer.length = 0;
 457         }
 458
 459         status = acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
 460         return status;
 461 #else
 462         return AE_OK;
 463 #endif
 464 }
 465 EXPORT_SYMBOL(acpi_evaluate_hotplug_ost);
 466
 467 /**
 468  * acpi_handle_path: Return the object path of handle
 469  *
 470  * Caller must free the returned buffer
 471  */
 472 static char *acpi_handle_path(acpi_handle handle)
 473 {
 474         struct acpi_buffer buffer = {
 475                 .length = ACPI_ALLOCATE_BUFFER,
 476                 .pointer = NULL
 477         };
 478
 479         if (in_interrupt() ||
 480             acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer) != AE_OK)
 481                 return NULL;
 482         return buffer.pointer;
 483 }
 484
 485 /**
 486  * acpi_handle_printk: Print message with ACPI prefix and object path
 487  *
 488  * This function is called through acpi_handle_<level> macros and prints
 489  * a message with ACPI prefix and object path.  This function acquires
 490  * the global namespace mutex to obtain an object path.  In interrupt
 491  * context, it shows the object path as <n/a>.
 492  */
 493 void
 494 acpi_handle_printk(const char *level, acpi_handle handle, const char *fmt, ...)
 495 {
 496         struct va_format vaf;
 497         va_list args;
 498         const char *path;
 499
 500         va_start(args, fmt);
 501         vaf.fmt = fmt;
 502         vaf.va = &args;
 503
 504         path = acpi_handle_path(handle);
 505         printk("%sACPI: %s: %pV", level, path ? path : "<n/a>" , &vaf);
 506
 507         va_end(args);
 508         kfree(path);
 509 }
 510 EXPORT_SYMBOL(acpi_handle_printk);
 511
 512 #if defined(CONFIG_DYNAMIC_DEBUG)
 513 /**
 514  * __acpi_handle_debug: pr_debug with ACPI prefix and object path
 515  *
 516  * This function is called through acpi_handle_debug macro and debug
 517  * prints a message with ACPI prefix and object path. This function
 518  * acquires the global namespace mutex to obtain an object path.  In
 519  * interrupt context, it shows the object path as <n/a>.
 520  */
 521 void
 522 __acpi_handle_debug(struct _ddebug *descriptor, acpi_handle handle,
 523                     const char *fmt, ...)
 524 {
 525         struct va_format vaf;
 526         va_list args;
 527         const char *path;
 528
 529         va_start(args, fmt);
 530         vaf.fmt = fmt;
 531         vaf.va = &args;
 532
 533         path = acpi_handle_path(handle);
 534         __dynamic_pr_debug(descriptor, "ACPI: %s: %pV", path ? path : "<n/a>", &vaf);
 535
 536         va_end(args);
 537         kfree(path);
 538 }
 539 EXPORT_SYMBOL(__acpi_handle_debug);
 540 #endif
 541
 542 /**
 543  * acpi_has_method: Check whether @handle has a method named @name
 544  * @handle: ACPI device handle
 545  * @name: name of object or method
 546  *
 547  * Check whether @handle has a method named @name.
 548  */
 549 bool acpi_has_method(acpi_handle handle, char *name)
 550 {
 551         acpi_handle tmp;
 552
 553         return ACPI_SUCCESS(acpi_get_handle(handle, name, &tmp));
 554 }
 555 EXPORT_SYMBOL(acpi_has_method);
 556
 557 acpi_status acpi_execute_simple_method(acpi_handle handle, char *method,
 558                                        u64 arg)
 559 {
 560         union acpi_object obj = { .type = ACPI_TYPE_INTEGER };
 561         struct acpi_object_list arg_list = { .count = 1, .pointer = &obj, };
 562
 563         obj.integer.value = arg;
 564
 565         return acpi_evaluate_object(handle, method, &arg_list, NULL);
 566 }
 567 EXPORT_SYMBOL(acpi_execute_simple_method);
 568
 569 /**
 570  * acpi_evaluate_ej0: Evaluate _EJ0 method for hotplug operations
 571  * @handle: ACPI device handle
 572  *
 573  * Evaluate device's _EJ0 method for hotplug operations.
 574  */
 575 acpi_status acpi_evaluate_ej0(acpi_handle handle)
 576 {
 577         acpi_status status;
 578
 579         status = acpi_execute_simple_method(handle, "_EJ0", 1);
 580         if (status == AE_NOT_FOUND)
 581                 acpi_handle_warn(handle, "No _EJ0 support for device\n");
 582         else if (ACPI_FAILURE(status))
 583                 acpi_handle_warn(handle, "Eject failed (0x%x)\n", status);
 584
 585         return status;
 586 }
 587
 588 /**
 589  * acpi_evaluate_lck: Evaluate _LCK method to lock/unlock device
 590  * @handle: ACPI device handle
 591  * @lock: lock device if non-zero, otherwise unlock device
 592  *
 593  * Evaluate device's _LCK method if present to lock/unlock device
 594  */
 595 acpi_status acpi_evaluate_lck(acpi_handle handle, int lock)
 596 {
 597         acpi_status status;
 598
 599         status = acpi_execute_simple_method(handle, "_LCK", !!lock);
 600         if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
 601                 if (lock)
 602                         acpi_handle_warn(handle,
 603                                 "Locking device failed (0x%x)\n", status);
 604                 else
 605                         acpi_handle_warn(handle,
 606                                 "Unlocking device failed (0x%x)\n", status);
 607         }
 608
 609         return status;
 610 }
 611
 612 /**
 613  * acpi_evaluate_dsm - evaluate device's _DSM method
 614  * @handle: ACPI device handle
 615  * @uuid: UUID of requested functions, should be 16 bytes
 616  * @rev: revision number of requested function
 617  * @func: requested function number
 618  * @argv4: the function specific parameter
 619  *
 620  * Evaluate device's _DSM method with specified UUID, revision id and
 621  * function number. Caller needs to free the returned object.
 622  *
 623  * Though ACPI defines the fourth parameter for _DSM should be a package,
 624  * some old BIOSes do expect a buffer or an integer etc.
 625  */
 626 union acpi_object *
 627 acpi_evaluate_dsm(acpi_handle handle, const u8 *uuid, int rev, int func,
 628                   union acpi_object *argv4)
 629 {
 630         acpi_status ret;
 631         struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
 632         union acpi_object params[4];
 633         struct acpi_object_list input = {
 634                 .count = 4,
 635                 .pointer = params,
 636         };
 637
 638         params[0].type = ACPI_TYPE_BUFFER;
 639         params[0].buffer.length = 16;
 640         params[0].buffer.pointer = (char *)uuid;
 641         params[1].type = ACPI_TYPE_INTEGER;
 642         params[1].integer.value = rev;
 643         params[2].type = ACPI_TYPE_INTEGER;
 644         params[2].integer.value = func;
 645         if (argv4) {
 646                 params[3] = *argv4;
 647         } else {
 648                 params[3].type = ACPI_TYPE_PACKAGE;
 649                 params[3].package.count = 0;
 650                 params[3].package.elements = NULL;
 651         }
 652
 653         ret = acpi_evaluate_object(handle, "_DSM", &input, &buf);
 654         if (ACPI_SUCCESS(ret))
 655                 return (union acpi_object *)buf.pointer;
 656
 657         if (ret != AE_NOT_FOUND)
 658                 acpi_handle_warn(handle,
 659                                 "failed to evaluate _DSM (0x%x)\n", ret);
 660
 661         return NULL;
 662 }
 663 EXPORT_SYMBOL(acpi_evaluate_dsm);
 664
 665 /**
 666  * acpi_check_dsm - check if _DSM method supports requested functions.
 667  * @handle: ACPI device handle
 668  * @uuid: UUID of requested functions, should be 16 bytes at least
 669  * @rev: revision number of requested functions
 670  * @funcs: bitmap of requested functions
 671  * @exclude: excluding special value, used to support i915 and nouveau
 672  *
 673  * Evaluate device's _DSM method to check whether it supports requested
 674  * functions. Currently only support 64 functions at maximum, should be
 675  * enough for now.
 676  */
 677 bool acpi_check_dsm(acpi_handle handle, const u8 *uuid, int rev, u64 funcs)
 678 {
 679         int i;
 680         u64 mask = 0;
 681         union acpi_object *obj;
 682
 683         if (funcs == 0)
 684                 return false;
 685
 686         obj = acpi_evaluate_dsm(handle, uuid, rev, 0, NULL);
 687         if (!obj)
 688                 return false;
 689
 690         /* For compatibility, old BIOSes may return an integer */
 691         if (obj->type == ACPI_TYPE_INTEGER)
 692                 mask = obj->integer.value;
 693         else if (obj->type == ACPI_TYPE_BUFFER)
 694                 for (i = 0; i < obj->buffer.length && i < 8; i++)
 695                         mask |= (((u8)obj->buffer.pointer[i]) << (i * 8));
 696         ACPI_FREE(obj);
 697
 698         /*
 699          * Bit 0 indicates whether there's support for any functions other than
 700          * function 0 for the specified UUID and revision.
 701          */
 702         if ((mask & 0x1) && (mask & funcs) == funcs)
 703                 return true;
 704
 705         return false;
 706 }
 707 EXPORT_SYMBOL(acpi_check_dsm);