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.
 122                  * If entry in pre_defined_names[] specifies an
 123                  * initial value, create the initial value.
 124                  */
 125                 if (init_val->val) {
 126                         status = acpi_os_predefined_override(init_val, &val);
 127                         if (ACPI_FAILURE(status)) {
 128                                 ACPI_ERROR((AE_INFO,
 129                                             "Could not override predefined %s",
 130                                             init_val->name));
 131                         }
 132
 133                         if (!val) {
 134                                 val = init_val->val;
 135                         }
 136
 137                         /*
 138                          * Entry requests an initial value, allocate a
 139                          * descriptor for it.
 140                          */
 141                         obj_desc =
 142                             acpi_ut_create_internal_object(init_val->type);
 143                         if (!obj_desc) {
 144                                 status = AE_NO_MEMORY;
 145                                 goto unlock_and_exit;
 146                         }
 147
 148                         /*
 149                          * Convert value string from table entry to
 150                          * internal representation. Only types actually
 151                          * used for initial values are implemented here.
 152                          */
 153                         switch (init_val->type) {
 154                         case ACPI_TYPE_METHOD:
 155                                 obj_desc->method.param_count =
 156                                     (u8) ACPI_TO_INTEGER(val);
 157                                 obj_desc->common.flags |= AOPOBJ_DATA_VALID;
 158
 159 #if defined (ACPI_ASL_COMPILER)
 160
 161                                 /* Save the parameter count for the i_aSL compiler */
 162
 163                                 new_node->value = obj_desc->method.param_count;
 164 #else
 165                                 /* Mark this as a very SPECIAL method */
 166
 167                                 obj_desc->method.method_flags =
 168                                     AML_METHOD_INTERNAL_ONLY;
 169                                 obj_desc->method.implementation =
 170                                     acpi_ut_osi_implementation;
 171 #endif
 172                                 break;
 173
 174                         case ACPI_TYPE_INTEGER:
 175
 176                                 obj_desc->integer.value = ACPI_TO_INTEGER(val);
 177                                 break;
 178
 179                         case ACPI_TYPE_STRING:
 180
 181                                 /*
 182                                  * Build an object around the static string
 183                                  */
 184                                 obj_desc->string.length =
 185                                     (u32) ACPI_STRLEN(val);
 186                                 obj_desc->string.pointer = val;
 187                                 obj_desc->common.flags |= AOPOBJ_STATIC_POINTER;
 188                                 break;
 189
 190                         case ACPI_TYPE_MUTEX:
 191
 192                                 obj_desc->mutex.node = new_node;
 193                                 obj_desc->mutex.sync_level =
 194                                     (u8) (ACPI_TO_INTEGER(val) - 1);
 195
 196                                 /* Create a mutex */
 197
 198                                 status =
 199                                     acpi_os_create_mutex(&obj_desc->mutex.
 200                                                          os_mutex);
 201                                 if (ACPI_FAILURE(status)) {
 202                                         acpi_ut_remove_reference(obj_desc);
 203                                         goto unlock_and_exit;
 204                                 }
 205
 206                                 /* Special case for ACPI Global Lock */
 207
 208                                 if (ACPI_STRCMP(init_val->name, "_GL_") == 0) {
 209                                         acpi_gbl_global_lock_mutex = obj_desc;
 210
 211                                         /* Create additional counting semaphore for global lock */
 212
 213                                         status =
 214                                             acpi_os_create_semaphore(1, 0,
 215                                                                      &acpi_gbl_global_lock_semaphore);
 216                                         if (ACPI_FAILURE(status)) {
 217                                                 acpi_ut_remove_reference
 218                                                     (obj_desc);
 219                                                 goto unlock_and_exit;
 220                                         }
 221                                 }
 222                                 break;
 223
 224                         default:
 225
 226                                 ACPI_ERROR((AE_INFO,
 227                                             "Unsupported initial type value %X",
 228                                             init_val->type));
 229                                 acpi_ut_remove_reference(obj_desc);
 230                                 obj_desc = NULL;
 231                                 continue;
 232                         }
 233
 234                         /* Store pointer to value descriptor in the Node */
 235
 236                         status = acpi_ns_attach_object(new_node, obj_desc,
 237                                                        ACPI_GET_OBJECT_TYPE
 238                                                        (obj_desc));
 239
 240                         /* Remove local reference to the object */
 241
 242                         acpi_ut_remove_reference(obj_desc);
 243                 }
 244         }
 245
 246       unlock_and_exit:
 247         (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
 248
 249         /* Save a handle to "_GPE", it is always present */
 250
 251         if (ACPI_SUCCESS(status)) {
 252                 status = acpi_ns_get_node(NULL, "\\_GPE", ACPI_NS_NO_UPSEARCH,
 253                                           &acpi_gbl_fadt_gpe_device);
 254         }
 255
 256         return_ACPI_STATUS(status);
 257 }
 258
 259 /*******************************************************************************
 260  *
 261  * FUNCTION:    acpi_ns_lookup
 262  *
 263  * PARAMETERS:  scope_info      - Current scope info block
 264  *              Pathname        - Search pathname, in internal format
 265  *                                (as represented in the AML stream)
 266  *              Type            - Type associated with name
 267  *              interpreter_mode - IMODE_LOAD_PASS2 => add name if not found
 268  *              Flags           - Flags describing the search restrictions
 269  *              walk_state      - Current state of the walk
 270  *              return_node     - Where the Node is placed (if found
 271  *                                or created successfully)
 272  *
 273  * RETURN:      Status
 274  *
 275  * DESCRIPTION: Find or enter the passed name in the name space.
 276  *              Log an error if name not found in Exec mode.
 277  *
 278  * MUTEX:       Assumes namespace is locked.
 279  *
 280  ******************************************************************************/
 281
 282 acpi_status
 283 acpi_ns_lookup(union acpi_generic_state *scope_info,
 284                char *pathname,
 285                acpi_object_type type,
 286                acpi_interpreter_mode interpreter_mode,
 287                u32 flags,
 288                struct acpi_walk_state *walk_state,
 289                struct acpi_namespace_node **return_node)
 290 {
 291         acpi_status status;
 292         char *path = pathname;
 293         struct acpi_namespace_node *prefix_node;
 294         struct acpi_namespace_node *current_node = NULL;
 295         struct acpi_namespace_node *this_node = NULL;
 296         u32 num_segments;
 297         u32 num_carats;
 298         acpi_name simple_name;
 299         acpi_object_type type_to_check_for;
 300         acpi_object_type this_search_type;
 301         u32 search_parent_flag = ACPI_NS_SEARCH_PARENT;
 302         u32 local_flags;
 303
 304         ACPI_FUNCTION_TRACE(ns_lookup);
 305
 306         if (!return_node) {
 307                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 308         }
 309
 310         local_flags = flags & ~(ACPI_NS_ERROR_IF_FOUND | ACPI_NS_SEARCH_PARENT);
 311         *return_node = ACPI_ENTRY_NOT_FOUND;
 312         acpi_gbl_ns_lookup_count++;
 313
 314         if (!acpi_gbl_root_node) {
 315                 return_ACPI_STATUS(AE_NO_NAMESPACE);
 316         }
 317
 318         /*
 319          * Get the prefix scope.
 320          * A null scope means use the root scope
 321          */
 322         if ((!scope_info) || (!scope_info->scope.node)) {
 323                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 324                                   "Null scope prefix, using root node (%p)\n",
 325                                   acpi_gbl_root_node));
 326
 327                 prefix_node = acpi_gbl_root_node;
 328         } else {
 329                 prefix_node = scope_info->scope.node;
 330                 if (ACPI_GET_DESCRIPTOR_TYPE(prefix_node) !=
 331                     ACPI_DESC_TYPE_NAMED) {
 332                         ACPI_ERROR((AE_INFO, "%p is not a namespace node [%s]",
 333                                     prefix_node,
 334                                     acpi_ut_get_descriptor_name(prefix_node)));
 335                         return_ACPI_STATUS(AE_AML_INTERNAL);
 336                 }
 337
 338                 if (!(flags & ACPI_NS_PREFIX_IS_SCOPE)) {
 339                         /*
 340                          * This node might not be a actual "scope" node (such as a
 341                          * Device/Method, etc.)  It could be a Package or other object node.
 342                          * Backup up the tree to find the containing scope node.
 343                          */
 344                         while (!acpi_ns_opens_scope(prefix_node->type) &&
 345                                prefix_node->type != ACPI_TYPE_ANY) {
 346                                 prefix_node =
 347                                     acpi_ns_get_parent_node(prefix_node);
 348                         }
 349                 }
 350         }
 351
 352         /* Save type   TBD: may be no longer necessary */
 353
 354         type_to_check_for = type;
 355
 356         /*
 357          * Begin examination of the actual pathname
 358          */
 359         if (!pathname) {
 360
 361                 /* A Null name_path is allowed and refers to the root */
 362
 363                 num_segments = 0;
 364                 this_node = acpi_gbl_root_node;
 365                 path = "";
 366
 367                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 368                                   "Null Pathname (Zero segments), Flags=%X\n",
 369                                   flags));
 370         } else {
 371                 /*
 372                  * Name pointer is valid (and must be in internal name format)
 373                  *
 374                  * Check for scope prefixes:
 375                  *
 376                  * As represented in the AML stream, a namepath consists of an
 377                  * optional scope prefix followed by a name segment part.
 378                  *
 379                  * If present, the scope prefix is either a Root Prefix (in
 380                  * which case the name is fully qualified), or one or more
 381                  * Parent Prefixes (in which case the name's scope is relative
 382                  * to the current scope).
 383                  */
 384                 if (*path == (u8) AML_ROOT_PREFIX) {
 385
 386                         /* Pathname is fully qualified, start from the root */
 387
 388                         this_node = acpi_gbl_root_node;
 389                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 390
 391                         /* Point to name segment part */
 392
 393                         path++;
 394
 395                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 396                                           "Path is absolute from root [%p]\n",
 397                                           this_node));
 398                 } else {
 399                         /* Pathname is relative to current scope, start there */
 400
 401                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 402                                           "Searching relative to prefix scope [%4.4s] (%p)\n",
 403                                           acpi_ut_get_node_name(prefix_node),
 404                                           prefix_node));
 405
 406                         /*
 407                          * Handle multiple Parent Prefixes (carat) by just getting
 408                          * the parent node for each prefix instance.
 409                          */
 410                         this_node = prefix_node;
 411                         num_carats = 0;
 412                         while (*path == (u8) AML_PARENT_PREFIX) {
 413
 414                                 /* Name is fully qualified, no search rules apply */
 415
 416                                 search_parent_flag = ACPI_NS_NO_UPSEARCH;
 417                                 /*
 418                                  * Point past this prefix to the name segment
 419                                  * part or the next Parent Prefix
 420                                  */
 421                                 path++;
 422
 423                                 /* Backup to the parent node */
 424
 425                                 num_carats++;
 426                                 this_node = acpi_ns_get_parent_node(this_node);
 427                                 if (!this_node) {
 428
 429                                         /* Current scope has no parent scope */
 430
 431                                         ACPI_ERROR((AE_INFO,
 432                                                     "ACPI path has too many parent prefixes (^) - reached beyond root node"));
 433                                         return_ACPI_STATUS(AE_NOT_FOUND);
 434                                 }
 435                         }
 436
 437                         if (search_parent_flag == ACPI_NS_NO_UPSEARCH) {
 438                                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 439                                                   "Search scope is [%4.4s], path has %d carat(s)\n",
 440                                                   acpi_ut_get_node_name
 441                                                   (this_node), num_carats));
 442                         }
 443                 }
 444
 445                 /*
 446                  * Determine the number of ACPI name segments in this pathname.
 447                  *
 448                  * The segment part consists of either:
 449                  *  - A Null name segment (0)
 450                  *  - A dual_name_prefix followed by two 4-byte name segments
 451                  *  - A multi_name_prefix followed by a byte indicating the
 452                  *      number of segments and the segments themselves.
 453                  *  - A single 4-byte name segment
 454                  *
 455                  * Examine the name prefix opcode, if any, to determine the number of
 456                  * segments.
 457                  */
 458                 switch (*path) {
 459                 case 0:
 460                         /*
 461                          * Null name after a root or parent prefixes. We already
 462                          * have the correct target node and there are no name segments.
 463                          */
 464                         num_segments = 0;
 465                         type = this_node->type;
 466
 467                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 468                                           "Prefix-only Pathname (Zero name segments), Flags=%X\n",
 469                                           flags));
 470                         break;
 471
 472                 case AML_DUAL_NAME_PREFIX:
 473
 474                         /* More than one name_seg, search rules do not apply */
 475
 476                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 477
 478                         /* Two segments, point to first name segment */
 479
 480                         num_segments = 2;
 481                         path++;
 482
 483                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 484                                           "Dual Pathname (2 segments, Flags=%X)\n",
 485                                           flags));
 486                         break;
 487
 488                 case AML_MULTI_NAME_PREFIX_OP:
 489
 490                         /* More than one name_seg, search rules do not apply */
 491
 492                         search_parent_flag = ACPI_NS_NO_UPSEARCH;
 493
 494                         /* Extract segment count, point to first name segment */
 495
 496                         path++;
 497                         num_segments = (u32) (u8) * path;
 498                         path++;
 499
 500                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 501                                           "Multi Pathname (%d Segments, Flags=%X)\n",
 502                                           num_segments, flags));
 503                         break;
 504
 505                 default:
 506                         /*
 507                          * Not a Null name, no Dual or Multi prefix, hence there is
 508                          * only one name segment and Pathname is already pointing to it.
 509                          */
 510                         num_segments = 1;
 511
 512                         ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 513                                           "Simple Pathname (1 segment, Flags=%X)\n",
 514                                           flags));
 515                         break;
 516                 }
 517
 518                 ACPI_DEBUG_EXEC(acpi_ns_print_pathname(num_segments, path));
 519         }
 520
 521         /*
 522          * Search namespace for each segment of the name. Loop through and
 523          * verify (or add to the namespace) each name segment.
 524          *
 525          * The object type is significant only at the last name
 526          * segment. (We don't care about the types along the path, only
 527          * the type of the final target object.)
 528          */
 529         this_search_type = ACPI_TYPE_ANY;
 530         current_node = this_node;
 531         while (num_segments && current_node) {
 532                 num_segments--;
 533                 if (!num_segments) {
 534                         /*
 535                          * This is the last segment, enable typechecking
 536                          */
 537                         this_search_type = type;
 538
 539                         /*
 540                          * Only allow automatic parent search (search rules) if the caller
 541                          * requested it AND we have a single, non-fully-qualified name_seg
 542                          */
 543                         if ((search_parent_flag != ACPI_NS_NO_UPSEARCH) &&
 544                             (flags & ACPI_NS_SEARCH_PARENT)) {
 545                                 local_flags |= ACPI_NS_SEARCH_PARENT;
 546                         }
 547
 548                         /* Set error flag according to caller */
 549
 550                         if (flags & ACPI_NS_ERROR_IF_FOUND) {
 551                                 local_flags |= ACPI_NS_ERROR_IF_FOUND;
 552                         }
 553                 }
 554
 555                 /* Extract one ACPI name from the front of the pathname */
 556
 557                 ACPI_MOVE_32_TO_32(&simple_name, path);
 558
 559                 /* Try to find the single (4 character) ACPI name */
 560
 561                 status =
 562                     acpi_ns_search_and_enter(simple_name, walk_state,
 563                                              current_node, interpreter_mode,
 564                                              this_search_type, local_flags,
 565                                              &this_node);
 566                 if (ACPI_FAILURE(status)) {
 567                         if (status == AE_NOT_FOUND) {
 568
 569                                 /* Name not found in ACPI namespace */
 570
 571                                 ACPI_DEBUG_PRINT((ACPI_DB_NAMES,
 572                                                   "Name [%4.4s] not found in scope [%4.4s] %p\n",
 573                                                   (char *)&simple_name,
 574                                                   (char *)&current_node->name,
 575                                                   current_node));
 576                         }
 577
 578                         *return_node = this_node;
 579                         return_ACPI_STATUS(status);
 580                 }
 581
 582                 /* More segments to follow? */
 583
 584                 if (num_segments > 0) {
 585                         /*
 586                          * If we have an alias to an object that opens a scope (such as a
 587                          * device or processor), we need to dereference the alias here so that
 588                          * we can access any children of the original node (via the remaining
 589                          * segments).
 590                          */
 591                         if (this_node->type == ACPI_TYPE_LOCAL_ALIAS) {
 592                                 if (!this_node->object) {
 593                                         return_ACPI_STATUS(AE_NOT_EXIST);
 594                                 }
 595
 596                                 if (acpi_ns_opens_scope
 597                                     (((struct acpi_namespace_node *)this_node->
 598                                       object)->type)) {
 599                                         this_node =
 600                                             (struct acpi_namespace_node *)
 601                                             this_node->object;
 602                                 }
 603                         }
 604                 }
 605
 606                 /* Special handling for the last segment (num_segments == 0) */
 607
 608                 else {
 609                         /*
 610                          * Sanity typecheck of the target object:
 611                          *
 612                          * If 1) This is the last segment (num_segments == 0)
 613                          *    2) And we are looking for a specific type
 614                          *       (Not checking for TYPE_ANY)
 615                          *    3) Which is not an alias
 616                          *    4) Which is not a local type (TYPE_SCOPE)
 617                          *    5) And the type of target object is known (not TYPE_ANY)
 618                          *    6) And target object does not match what we are looking for
 619                          *
 620                          * Then we have a type mismatch. Just warn and ignore it.
 621                          */
 622                         if ((type_to_check_for != ACPI_TYPE_ANY) &&
 623                             (type_to_check_for != ACPI_TYPE_LOCAL_ALIAS) &&
 624                             (type_to_check_for != ACPI_TYPE_LOCAL_METHOD_ALIAS)
 625                             && (type_to_check_for != ACPI_TYPE_LOCAL_SCOPE)
 626                             && (this_node->type != ACPI_TYPE_ANY)
 627                             && (this_node->type != type_to_check_for)) {
 628
 629                                 /* Complain about a type mismatch */
 630
 631                                 ACPI_WARNING((AE_INFO,
 632                                               "NsLookup: Type mismatch on %4.4s (%s), searching for (%s)",
 633                                               ACPI_CAST_PTR(char, &simple_name),
 634                                               acpi_ut_get_type_name(this_node->
 635                                                                     type),
 636                                               acpi_ut_get_type_name
 637                                               (type_to_check_for)));
 638                         }
 639
 640                         /*
 641                          * If this is the last name segment and we are not looking for a
 642                          * specific type, but the type of found object is known, use that type
 643                          * to (later) see if it opens a scope.
 644                          */
 645                         if (type == ACPI_TYPE_ANY) {
 646                                 type = this_node->type;
 647                         }
 648                 }
 649
 650                 /* Point to next name segment and make this node current */
 651
 652                 path += ACPI_NAME_SIZE;
 653                 current_node = this_node;
 654         }
 655
 656         /*
 657          * Always check if we need to open a new scope
 658          */
 659         if (!(flags & ACPI_NS_DONT_OPEN_SCOPE) && (walk_state)) {
 660                 /*
 661                  * If entry is a type which opens a scope, push the new scope on the
 662                  * scope stack.
 663                  */
 664                 if (acpi_ns_opens_scope(type)) {
 665                         status =
 666                             acpi_ds_scope_stack_push(this_node, type,
 667                                                      walk_state);
 668                         if (ACPI_FAILURE(status)) {
 669                                 return_ACPI_STATUS(status);
 670                         }
 671                 }
 672         }
 673
 674         *return_node = this_node;
 675         return_ACPI_STATUS(AE_OK);
 676 }