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