git.oblomov.eu Git - linux-2.6/blob - drivers/acpi/acpica/nsaccess.c

   1 /*******************************************************************************
   2  *
   3  * Module Name: nsaccess - Top-level functions for accessing ACPI namespace
   4  *
   5  ******************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2008, Intel Corp.
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions, and the following disclaimer,
  16  *    without modification.
  17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
  18  *    substantially similar to the "NO WARRANTY" disclaimer below
  19  *    ("Disclaimer") and any redistribution must be conditioned upon
  20  *    including a substantially similar Disclaimer requirement for further
  21  *    binary redistribution.
  22  * 3. Neither the names of the above-listed copyright holders nor the names
  23  *    of any contributors may be used to endorse or promote products derived
  24  *    from this software without specific prior written permission.
  25  *
  26  * Alternatively, this software may be distributed under the terms of the
  27  * GNU General Public License ("GPL") version 2 as published by the Free
  28  * Software Foundation.
  29  *
  30  * NO WARRANTY
  31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
  34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  41  * POSSIBILITY OF SUCH DAMAGES.
  42  */
  43
  44 #include <acpi/acpi.h>
  45 #include "accommon.h"
  46 #include "amlcode.h"
  47 #include "acnamesp.h"
  48 #include "acdispat.h"
  49
  50 #define _COMPONENT          ACPI_NAMESPACE
  51 ACPI_MODULE_NAME("nsaccess")
  52
  53 /*******************************************************************************
  54  *
  55  * FUNCTION:    acpi_ns_root_initialize
  56  *
  57  * PARAMETERS:  None
  58  *
  59  * RETURN:      Status
  60  *
  61  * DESCRIPTION: Allocate and initialize the default root named objects
  62  *
  63  * MUTEX:       Locks namespace for entire execution
  64  *
  65  ******************************************************************************/
  66 acpi_status acpi_ns_root_initialize(void)
  67 {
  68         acpi_status status;
  69         const struct acpi_predefined_names *init_val = NULL;
  70         struct acpi_namespace_node *new_node;
  71         union acpi_operand_object *obj_desc;
  72         acpi_string val = NULL;
  73
  74         ACPI_FUNCTION_TRACE(ns_root_initialize);
  75
  76         status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
  77         if (ACPI_FAILURE(status)) {
  78                 return_ACPI_STATUS(status);
  79         }
  80
  81         /*
  82          * The global root ptr is initially NULL, so a non-NULL value indicates
  83          * that acpi_ns_root_initialize() has already been called; just return.
  84          */
  85         if (acpi_gbl_root_node) {
  86                 status = AE_OK;
  87                 goto unlock_and_exit;
  88         }
  89
  90         /*
  91          * Tell the rest of the subsystem that the root is initialized
  92          * (This is OK because the namespace is locked)
  93          */
  94         acpi_gbl_root_node = &acpi_gbl_root_node_struct;
  95
  96         /* Enter the pre-defined names in the name table */
  97
  98         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
  99                           "Entering predefined entries into namespace\n"));
 100
 101         for (init_val = acpi_gbl_pre_defined_names; init_val->name; init_val++) {
 102
 103                 /* _OSI is optional for now, will be permanent later */
 104
 105                 if (!ACPI_STRCMP(init_val->name, "_OSI")
 106                     && !acpi_gbl_create_osi_method) {
 107                         continue;
 108                 }
 109
 110                 status = acpi_ns_lookup(NULL, init_val->name, init_val->type,
 111                                         ACPI_IMODE_LOAD_PASS2,
 112                                         ACPI_NS_NO_UPSEARCH, NULL, &new_node);
 113
 114                 if (ACPI_FAILURE(status) || (!new_node)) {      /* Must be on same line for code converter */
 115                         ACPI_EXCEPTION((AE_INFO, status,
 116                                         "Could not create predefined name %s",
 117                                         init_val->name));
 118                 }
 119
 120                 /*
 121                  * Name entered successfully. If entry in pre_defined_names[] specifies
 122                  * an initial value, create the initial value.
 123                  */
 124                 if (init_val->val) {
 125                         status = acpi_os_predefined_override(init_val, &val);
 126                         if (ACPI_FAILURE(status)) {
 127                                 ACPI_ERROR((AE_INFO,
 128                                             "Could not override predefined %s",
 129                                             init_val->name));
 130                         }
 131
 132                         if (!val) {
 133                                 val = init_val->val;
 134                         }
 135
 136                         /*
 137                          * Entry requests an initial value, allocate a
 138                          * descriptor for it.
 139                          */
 140                         obj_desc =
 141                             acpi_ut_create_internal_object(init_val->type);
 142                         if (!obj_desc) {
 143                                 status = AE_NO_MEMORY;
 144                                 goto unlock_and_exit;
 145                         }
 146
 147                         /*
 148                          * Convert value string from table entry to
 149                          * internal representation. Only types actually
 150                          * used for initial values are implemented here.
 151                          */
 152                         switch (init_val->type) {
 153                         case ACPI_TYPE_METHOD:
 154                                 obj_desc->method.param_count =
 155                                     (u8) ACPI_TO_INTEGER(val);
 156                                 obj_desc->common.flags |= AOPOBJ_DATA_VALID;
 157
 158 #if defined (ACPI_ASL_COMPILER)
 159
 160                                 /* Save the parameter count for the i_aSL compiler */
 161
 162                                 new_node->value = obj_desc->method.param_count;
 163 #else
 164                                 /* Mark this as a very SPECIAL method */
 165
 166                                 obj_desc->method.method_flags =
 167                                     AML_METHOD_INTERNAL_ONLY;
 168                                 obj_desc->method.implementation =
 169                                     acpi_ut_osi_implementation;
 170 #endif
 171                                 break;
 172
 173                         case ACPI_TYPE_INTEGER:
 174
 175                                 obj_desc->integer.value = ACPI_TO_INTEGER(val);
 176                                 break;
 177
 178                         case ACPI_TYPE_STRING:
 179
 180                                 /* Build an object around the static string */
 181
 182                                 obj_desc->string.length =
 183                                     (u32) ACPI_STRLEN(val);
 184                                 obj_desc->string.pointer = val;
 185                                 obj_desc->common.flags |= AOPOBJ_STATIC_POINTER;
 186                                 break;
 187
 188                         case ACPI_TYPE_MUTEX:
 189
 190                                 obj_desc->mutex.node = new_node;
 191                                 obj_desc->mutex.sync_level =
 192                                     (u8) (ACPI_TO_INTEGER(val) - 1);
 193
 194                                 /* Create a mutex */
 195
 196                                 status =
 197                                     acpi_os_create_mutex(&obj_desc->mutex.
 198                                                          os_mutex);
 199                                 if (ACPI_FAILURE(status)) {
 200                                         acpi_ut_remove_reference(obj_desc);
 201                                         goto unlock_and_exit;
 202                                 }
 203
 204                                 /* Special case for ACPI Global Lock */
 205
 206                                 if (ACPI_STRCMP(init_val->name, "_GL_") == 0) {
 207                                         acpi_gbl_global_lock_mutex = obj_desc;
 208
 209                                         /* Create additional counting semaphore for global lock */
 210
 211                                         status =
 212                                             acpi_os_create_semaphore(1, 0,
 213                                                                      &acpi_gbl_global_lock_semaphore);
 214                                         if (ACPI_FAILURE(status)) {
 215                                                 acpi_ut_remove_reference
 216                                                     (obj_desc);
 217                                                 goto unlock_and_exit;
 218                                         }
 219                                 }
 220                                 break;
 221
 222                         default:
 223
 224                                 ACPI_ERROR((AE_INFO,
 225                                             "Unsupported initial type value %X",
 226                                             init_val->type));
 227                                 acpi_ut_remove_reference(obj_desc);
 228                                 obj_desc = NULL;
 229                                 continue;
 230                         }
 231
 232                         /* Store pointer to value descriptor in the Node */
 233
 234                         status = acpi_ns_attach_object(new_node, obj_desc,
 235                                                        obj_desc->common.type);
 236
 237                         /* Remove local reference to the object */
 238
 239                         acpi_ut_remove_reference(obj_desc);
 240                 }
 241         }
 242
 243       unlock_and_exit:
 244         (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
 245
 246         /* Save a handle to "_GPE", it is always present */
 247
 248         if (ACPI_SUCCESS(status)) {
 249                 status = acpi_ns_get_node(NULL, "\\_GPE", ACPI_NS_NO_UPSEARCH,
 250                                           &acpi_gbl_fadt_gpe_device);
 251         }
 252
 253         return_ACPI_STATUS(status);
 254 }
 255
 256 /*******************************************************************************
 257  *
 258  * FUNCTION:    acpi_ns_lookup
 259  *
 260  * PARAMETERS:  scope_info      - Current scope info block
 261  *              Pathname        - Search pathname, in internal format
 262  *                                (as represented in the AML stream)
 263  *              Type            - Type associated with name
 264  *              interpreter_mode - IMODE_LOAD_PASS2 => add name if not found
 265  *              Flags           - Flags describing the search restrictions
 266  *              walk_state      - Current state of the walk
 267  *              return_node     - Where the Node is placed (if found
 268  *                                or created successfully)
 269  *
 270  * RETURN:      Status
 271  *
 272  * DESCRIPTION: Find or enter the passed name in the name space.
 273  *              Log an error if name not found in Exec mode.
 274  *
 275  * MUTEX:       Assumes namespace is locked.
 276  *
 277  ******************************************************************************/
 278
 279 acpi_status
 280 acpi_ns_lookup(union acpi_generic_state *scope_info,
 281                char *pathname,
 282                acpi_object_type type,
 283                acpi_interpreter_mode interpreter_mode,
 284                u32 flags,
 285                struct acpi_walk_state *walk_state,
 286                struct acpi_namespace_node **return_node)
 287 {
 288         acpi_status status;
 289         char *path = pathname;
 290         struct acpi_namespace_node *prefix_node;
 291         struct acpi_namespace_node *current_node = NULL;
 292         struct acpi_namespace_node *this_node = NULL;
 293         u32 num_segments;
 294         u32 num_carats;
 295         acpi_name simple_name;
 296         acpi_object_type type_to_check_for;
 297         acpi_object_type this_search_type;
 298         u32 search_parent_flag = ACPI_NS_SEARCH_PARENT;
 299         u32 local_flags;
 300
 301         ACPI_FUNCTION_TRACE(ns_lookup);
 302
 303         if (!return_node) {
 304                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 305         }
 306
 307         local_flags = flags & ~(ACPI_NS_ERROR_IF_FOUND | ACPI_NS_SEARCH_PARENT);
 308         *return_node = ACPI_ENTRY_NOT_FOUND;
 309         acpi_gbl_ns_lookup_count++;
 310
 311         if (!acpi_gbl_root_node) {
 312                 return_ACPI_STATUS(AE_NO_NAMESPACE);
 313         }
 314
 315         /* Get the prefix scope. A null scope means use the root scope */
 316
 317         if ((!scope_info) || (!scope_info->scope.node)) {
 318                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 319                                   "Null scope prefix, using root node (%p)\n",
 320                                   acpi_gbl_root_node));
 321
 322                 prefix_node = acpi_gbl_root_node;
 323         } else {
 324                 prefix_node = scope_info->scope.node;
 325                 if (ACPI_GET_DESCRIPTOR_TYPE(prefix_node) !=
 326                     ACPI_DESC_TYPE_NAMED) {
 327                         ACPI_ERROR((AE_INFO, "%p is not a namespace node [%s]",
 328                                     prefix_node,
 329                                     acpi_ut_get_descriptor_name(prefix_node)));
 330                         return_ACPI_STATUS(AE_AML_INTERNAL);
 331                 }
 332
 333                 if (!(flags & ACPI_NS_PREFIX_IS_SCOPE)) {
 334                         /*
 335                          * This node might not be a actual "scope" node (such as a
 336                          * Device/Method, etc.)  It could be a Package or other object
 337                          * node. Backup up the tree to find the containing scope node.
 338                          */
 339                         while (!acpi_ns_opens_scope(prefix_node->type) &&
 340                                prefix_node->type != ACPI_TYPE_ANY) {
 341                                 prefix_node =
 342                                     acpi_ns_get_parent_node(prefix_node);
 343                         }
 344                 }
 345         }
 346
 347         /* Save type. TBD: may be no longer necessary */
 348
 349         type_to_check_for = type;
 350
 351         /*
 352          * Begin examination of the actual pathname
 353          */
 354         if (!pathname) {
 355
 356                 /* A Null name_path is allowed and refers to the root */
 357
 358                 num_segments = 0;
 359                 this_node = acpi_gbl_root_node;
 360                 path = "";
 361
 362                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 363                                   "Null Pathname (Zero segments), Flags=%X\n",
 364                                   flags));
 365         } else {
 366                 /*
 367                  * Name pointer is valid (and must be in internal name format)
 368                  *
 369                  * Check for scope prefixes:
 370                  *
 371                  * As represented in the AML stream, a namepath consists of an
 372                  * optional scope prefix followed by a name segment part.
 373                  *
 374                  * If present, the scope prefix is either a Root Prefix (in
 375                  * which case the name is fully qualified), or one or more
 376                  * Parent Prefixes (in which case the name's scope is relative
 377                  * to the current scope).
 378                  */
 379                 if (*path == (u8) AML_ROOT_PREFIX) {
 380
 381                         /* Pathname is fully qualified, start from the root */
 382
 383                         this_node = acpi_gbl_root_node;
 384                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 385
 386                         /* Point to name segment part */
 387
 388                         path++;
 389
 390                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 391                                           "Path is absolute from root [%p]\n",
 392                                           this_node));
 393                 } else {
 394                         /* Pathname is relative to current scope, start there */
 395
 396                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 397                                           "Searching relative to prefix scope [%4.4s] (%p)\n",
 398                                           acpi_ut_get_node_name(prefix_node),
 399                                           prefix_node));
 400
 401                         /*
 402                          * Handle multiple Parent Prefixes (carat) by just getting
 403                          * the parent node for each prefix instance.
 404                          */
 405                         this_node = prefix_node;
 406                         num_carats = 0;
 407                         while (*path == (u8) AML_PARENT_PREFIX) {
 408
 409                                 /* Name is fully qualified, no search rules apply */
 410
 411                                 search_parent_flag = ACPI_NS_NO_UPSEARCH;
 412
 413                                 /*
 414                                  * Point past this prefix to the name segment
 415                                  * part or the next Parent Prefix
 416                                  */
 417                                 path++;
 418
 419                                 /* Backup to the parent node */
 420
 421                                 num_carats++;
 422                                 this_node = acpi_ns_get_parent_node(this_node);
 423                                 if (!this_node) {
 424
 425                                         /* Current scope has no parent scope */
 426
 427                                         ACPI_ERROR((AE_INFO,
 428                                                     "ACPI path has too many parent prefixes (^) "
 429                                                     "- reached beyond root node"));
 430                                         return_ACPI_STATUS(AE_NOT_FOUND);
 431                                 }
 432                         }
 433
 434                         if (search_parent_flag == ACPI_NS_NO_UPSEARCH) {
 435                                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 436                                                   "Search scope is [%4.4s], path has %d carat(s)\n",
 437                                                   acpi_ut_get_node_name
 438                                                   (this_node), num_carats));
 439                         }
 440                 }
 441
 442                 /*
 443                  * Determine the number of ACPI name segments in this pathname.
 444                  *
 445                  * The segment part consists of either:
 446                  *  - A Null name segment (0)
 447                  *  - A dual_name_prefix followed by two 4-byte name segments
 448                  *  - A multi_name_prefix followed by a byte indicating the
 449                  *      number of segments and the segments themselves.
 450                  *  - A single 4-byte name segment
 451                  *
 452                  * Examine the name prefix opcode, if any, to determine the number of
 453                  * segments.
 454                  */
 455                 switch (*path) {
 456                 case 0:
 457                         /*
 458                          * Null name after a root or parent prefixes. We already
 459                          * have the correct target node and there are no name segments.
 460                          */
 461                         num_segments = 0;
 462                         type = this_node->type;
 463
 464                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 465                                           "Prefix-only Pathname (Zero name segments), Flags=%X\n",
 466                                           flags));
 467                         break;
 468
 469                 case AML_DUAL_NAME_PREFIX:
 470
 471                         /* More than one name_seg, search rules do not apply */
 472
 473                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 474
 475                         /* Two segments, point to first name segment */
 476
 477                         num_segments = 2;
 478                         path++;
 479
 480                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 481                                           "Dual Pathname (2 segments, Flags=%X)\n",
 482                                           flags));
 483                         break;
 484
 485                 case AML_MULTI_NAME_PREFIX_OP:
 486
 487                         /* More than one name_seg, search rules do not apply */
 488
 489                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 490
 491                         /* Extract segment count, point to first name segment */
 492
 493                         path++;
 494                         num_segments = (u32) (u8) * path;
 495                         path++;
 496
 497                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 498                                           "Multi Pathname (%d Segments, Flags=%X)\n",
 499                                           num_segments, flags));
 500                         break;
 501
 502                 default:
 503                         /*
 504                          * Not a Null name, no Dual or Multi prefix, hence there is
 505                          * only one name segment and Pathname is already pointing to it.
 506                          */
 507                         num_segments = 1;
 508
 509                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 510                                           "Simple Pathname (1 segment, Flags=%X)\n",
 511                                           flags));
 512                         break;
 513                 }
 514
 515                 ACPI_DEBUG_EXEC(acpi_ns_print_pathname(num_segments, path));
 516         }
 517
 518         /*
 519          * Search namespace for each segment of the name. Loop through and
 520          * verify (or add to the namespace) each name segment.
 521          *
 522          * The object type is significant only at the last name
 523          * segment. (We don't care about the types along the path, only
 524          * the type of the final target object.)
 525          */
 526         this_search_type = ACPI_TYPE_ANY;
 527         current_node = this_node;
 528         while (num_segments && current_node) {
 529                 num_segments--;
 530                 if (!num_segments) {
 531
 532                         /* This is the last segment, enable typechecking */
 533
 534                         this_search_type = type;
 535
 536                         /*
 537                          * Only allow automatic parent search (search rules) if the caller
 538                          * requested it AND we have a single, non-fully-qualified name_seg
 539                          */
 540                         if ((search_parent_flag != ACPI_NS_NO_UPSEARCH) &&
 541                             (flags & ACPI_NS_SEARCH_PARENT)) {
 542                                 local_flags |= ACPI_NS_SEARCH_PARENT;
 543                         }
 544
 545                         /* Set error flag according to caller */
 546
 547                         if (flags & ACPI_NS_ERROR_IF_FOUND) {
 548                                 local_flags |= ACPI_NS_ERROR_IF_FOUND;
 549                         }
 550                 }
 551
 552                 /* Extract one ACPI name from the front of the pathname */
 553
 554                 ACPI_MOVE_32_TO_32(&simple_name, path);
 555
 556                 /* Try to find the single (4 character) ACPI name */
 557
 558                 status =
 559                     acpi_ns_search_and_enter(simple_name, walk_state,
 560                                              current_node, interpreter_mode,
 561                                              this_search_type, local_flags,
 562                                              &this_node);
 563                 if (ACPI_FAILURE(status)) {
 564                         if (status == AE_NOT_FOUND) {
 565
 566                                 /* Name not found in ACPI namespace */
 567
 568                                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 569                                                   "Name [%4.4s] not found in scope [%4.4s] %p\n",
 570                                                   (char *)&simple_name,
 571                                                   (char *)&current_node->name,
 572                                                   current_node));
 573                         }
 574
 575                         *return_node = this_node;
 576                         return_ACPI_STATUS(status);
 577                 }
 578
 579                 /* More segments to follow? */
 580
 581                 if (num_segments > 0) {
 582                         /*
 583                          * If we have an alias to an object that opens a scope (such as a
 584                          * device or processor), we need to dereference the alias here so
 585                          * that we can access any children of the original node (via the
 586                          * remaining segments).
 587                          */
 588                         if (this_node->type == ACPI_TYPE_LOCAL_ALIAS) {
 589                                 if (!this_node->object) {
 590                                         return_ACPI_STATUS(AE_NOT_EXIST);
 591                                 }
 592
 593                                 if (acpi_ns_opens_scope
 594                                     (((struct acpi_namespace_node *)
 595                                       this_node->object)->type)) {
 596                                         this_node =
 597                                             (struct acpi_namespace_node *)
 598                                             this_node->object;
 599                                 }
 600                         }
 601                 }
 602
 603                 /* Special handling for the last segment (num_segments == 0) */
 604
 605                 else {
 606                         /*
 607                          * Sanity typecheck of the target object:
 608                          *
 609                          * If 1) This is the last segment (num_segments == 0)
 610                          *    2) And we are looking for a specific type
 611                          *       (Not checking for TYPE_ANY)
 612                          *    3) Which is not an alias
 613                          *    4) Which is not a local type (TYPE_SCOPE)
 614                          *    5) And the type of target object is known (not TYPE_ANY)
 615                          *    6) And target object does not match what we are looking for
 616                          *
 617                          * Then we have a type mismatch. Just warn and ignore it.
 618                          */
 619                         if ((type_to_check_for != ACPI_TYPE_ANY) &&
 620                             (type_to_check_for != ACPI_TYPE_LOCAL_ALIAS) &&
 621                             (type_to_check_for != ACPI_TYPE_LOCAL_METHOD_ALIAS)
 622                             && (type_to_check_for != ACPI_TYPE_LOCAL_SCOPE)
 623                             && (this_node->type != ACPI_TYPE_ANY)
 624                             && (this_node->type != type_to_check_for)) {
 625
 626                                 /* Complain about a type mismatch */
 627
 628                                 ACPI_WARNING((AE_INFO,
 629                                               "NsLookup: Type mismatch on %4.4s (%s), searching for (%s)",
 630                                               ACPI_CAST_PTR(char, &simple_name),
 631                                               acpi_ut_get_type_name(this_node->
 632                                                                     type),
 633                                               acpi_ut_get_type_name
 634                                               (type_to_check_for)));
 635                         }
 636
 637                         /*
 638                          * If this is the last name segment and we are not looking for a
 639                          * specific type, but the type of found object is known, use that
 640                          * type to (later) see if it opens a scope.
 641                          */
 642                         if (type == ACPI_TYPE_ANY) {
 643                                 type = this_node->type;
 644                         }
 645                 }
 646
 647                 /* Point to next name segment and make this node current */
 648
 649                 path += ACPI_NAME_SIZE;
 650                 current_node = this_node;
 651         }
 652
 653         /* Always check if we need to open a new scope */
 654
 655         if (!(flags & ACPI_NS_DONT_OPEN_SCOPE) && (walk_state)) {
 656                 /*
 657                  * If entry is a type which opens a scope, push the new scope on the
 658                  * scope stack.
 659                  */
 660                 if (acpi_ns_opens_scope(type)) {
 661                         status =
 662                             acpi_ds_scope_stack_push(this_node, type,
 663                                                      walk_state);
 664                         if (ACPI_FAILURE(status)) {
 665                                 return_ACPI_STATUS(status);
 666                         }
 667                 }
 668         }
 669
 670         *return_node = this_node;
 671         return_ACPI_STATUS(AE_OK);
 672 }