drivers/acpi/acpica/nsutils.c

   1 /******************************************************************************
   2  *
   3  * Module Name: nsutils - Utilities for accessing ACPI namespace, accessing
   4  *                        parents and siblings and Scope manipulation
   5  *
   6  *****************************************************************************/
   7
   8 /*
   9  * Copyright (C) 2000 - 2012, Intel Corp.
  10  * All rights reserved.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions, and the following disclaimer,
  17  *    without modification.
  18  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
  19  *    substantially similar to the "NO WARRANTY" disclaimer below
  20  *    ("Disclaimer") and any redistribution must be conditioned upon
  21  *    including a substantially similar Disclaimer requirement for further
  22  *    binary redistribution.
  23  * 3. Neither the names of the above-listed copyright holders nor the names
  24  *    of any contributors may be used to endorse or promote products derived
  25  *    from this software without specific prior written permission.
  26  *
  27  * Alternatively, this software may be distributed under the terms of the
  28  * GNU General Public License ("GPL") version 2 as published by the Free
  29  * Software Foundation.
  30  *
  31  * NO WARRANTY
  32  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  33  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  34  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
  35  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  36  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  37  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  38  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  39  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  40  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  41  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  42  * POSSIBILITY OF SUCH DAMAGES.
  43  */
  44
  45 #include <acpi/acpi.h>
  46 #include "accommon.h"
  47 #include "acnamesp.h"
  48 #include "amlcode.h"
  49 #include "actables.h"
  50
  51 #define _COMPONENT          ACPI_NAMESPACE
  52 ACPI_MODULE_NAME("nsutils")
  53
  54 /* Local prototypes */
  55 static u8 acpi_ns_valid_path_separator(char sep);
  56
  57 #ifdef ACPI_OBSOLETE_FUNCTIONS
  58 acpi_name acpi_ns_find_parent_name(struct acpi_namespace_node *node_to_search);
  59 #endif
  60
  61 /*******************************************************************************
  62  *
  63  * FUNCTION:    acpi_ns_print_node_pathname
  64  *
  65  * PARAMETERS:  node            - Object
  66  *              message         - Prefix message
  67  *
  68  * DESCRIPTION: Print an object's full namespace pathname
  69  *              Manages allocation/freeing of a pathname buffer
  70  *
  71  ******************************************************************************/
  72
  73 void
  74 acpi_ns_print_node_pathname(struct acpi_namespace_node *node,
  75                             const char *message)
  76 {
  77         struct acpi_buffer buffer;
  78         acpi_status status;
  79
  80         if (!node) {
  81                 acpi_os_printf("[NULL NAME]");
  82                 return;
  83         }
  84
  85         /* Convert handle to full pathname and print it (with supplied message) */
  86
  87         buffer.length = ACPI_ALLOCATE_LOCAL_BUFFER;
  88
  89         status = acpi_ns_handle_to_pathname(node, &buffer);
  90         if (ACPI_SUCCESS(status)) {
  91                 if (message) {
  92                         acpi_os_printf("%s ", message);
  93                 }
  94
  95                 acpi_os_printf("[%s] (Node %p)", (char *)buffer.pointer, node);
  96                 ACPI_FREE(buffer.pointer);
  97         }
  98 }
  99
 100 /*******************************************************************************
 101  *
 102  * FUNCTION:    acpi_ns_valid_root_prefix
 103  *
 104  * PARAMETERS:  prefix          - Character to be checked
 105  *
 106  * RETURN:      TRUE if a valid prefix
 107  *
 108  * DESCRIPTION: Check if a character is a valid ACPI Root prefix
 109  *
 110  ******************************************************************************/
 111
 112 u8 acpi_ns_valid_root_prefix(char prefix)
 113 {
 114
 115         return ((u8) (prefix == '\\'));
 116 }
 117
 118 /*******************************************************************************
 119  *
 120  * FUNCTION:    acpi_ns_valid_path_separator
 121  *
 122  * PARAMETERS:  sep         - Character to be checked
 123  *
 124  * RETURN:      TRUE if a valid path separator
 125  *
 126  * DESCRIPTION: Check if a character is a valid ACPI path separator
 127  *
 128  ******************************************************************************/
 129
 130 static u8 acpi_ns_valid_path_separator(char sep)
 131 {
 132
 133         return ((u8) (sep == '.'));
 134 }
 135
 136 /*******************************************************************************
 137  *
 138  * FUNCTION:    acpi_ns_get_type
 139  *
 140  * PARAMETERS:  node        - Parent Node to be examined
 141  *
 142  * RETURN:      Type field from Node whose handle is passed
 143  *
 144  * DESCRIPTION: Return the type of a Namespace node
 145  *
 146  ******************************************************************************/
 147
 148 acpi_object_type acpi_ns_get_type(struct acpi_namespace_node * node)
 149 {
 150         ACPI_FUNCTION_TRACE(ns_get_type);
 151
 152         if (!node) {
 153                 ACPI_WARNING((AE_INFO, "Null Node parameter"));
 154                 return_UINT32(ACPI_TYPE_ANY);
 155         }
 156
 157         return_UINT32((acpi_object_type) node->type);
 158 }
 159
 160 /*******************************************************************************
 161  *
 162  * FUNCTION:    acpi_ns_local
 163  *
 164  * PARAMETERS:  type        - A namespace object type
 165  *
 166  * RETURN:      LOCAL if names must be found locally in objects of the
 167  *              passed type, 0 if enclosing scopes should be searched
 168  *
 169  * DESCRIPTION: Returns scope rule for the given object type.
 170  *
 171  ******************************************************************************/
 172
 173 u32 acpi_ns_local(acpi_object_type type)
 174 {
 175         ACPI_FUNCTION_TRACE(ns_local);
 176
 177         if (!acpi_ut_valid_object_type(type)) {
 178
 179                 /* Type code out of range  */
 180
 181                 ACPI_WARNING((AE_INFO, "Invalid Object Type 0x%X", type));
 182                 return_UINT32(ACPI_NS_NORMAL);
 183         }
 184
 185         return_UINT32((u32) acpi_gbl_ns_properties[type] & ACPI_NS_LOCAL);
 186 }
 187
 188 /*******************************************************************************
 189  *
 190  * FUNCTION:    acpi_ns_get_internal_name_length
 191  *
 192  * PARAMETERS:  info            - Info struct initialized with the
 193  *                                external name pointer.
 194  *
 195  * RETURN:      None
 196  *
 197  * DESCRIPTION: Calculate the length of the internal (AML) namestring
 198  *              corresponding to the external (ASL) namestring.
 199  *
 200  ******************************************************************************/
 201
 202 void acpi_ns_get_internal_name_length(struct acpi_namestring_info *info)
 203 {
 204         const char *next_external_char;
 205         u32 i;
 206
 207         ACPI_FUNCTION_ENTRY();
 208
 209         next_external_char = info->external_name;
 210         info->num_carats = 0;
 211         info->num_segments = 0;
 212         info->fully_qualified = FALSE;
 213
 214         /*
 215          * For the internal name, the required length is 4 bytes per segment, plus
 216          * 1 each for root_prefix, multi_name_prefix_op, segment count, trailing null
 217          * (which is not really needed, but no there's harm in putting it there)
 218          *
 219          * strlen() + 1 covers the first name_seg, which has no path separator
 220          */
 221         if (acpi_ns_valid_root_prefix(*next_external_char)) {
 222                 info->fully_qualified = TRUE;
 223                 next_external_char++;
 224
 225                 /* Skip redundant root_prefix, like \\_SB.PCI0.SBRG.EC0 */
 226
 227                 while (acpi_ns_valid_root_prefix(*next_external_char)) {
 228                         next_external_char++;
 229                 }
 230         } else {
 231                 /* Handle Carat prefixes */
 232
 233                 while (*next_external_char == '^') {
 234                         info->num_carats++;
 235                         next_external_char++;
 236                 }
 237         }
 238
 239         /*
 240          * Determine the number of ACPI name "segments" by counting the number of
 241          * path separators within the string. Start with one segment since the
 242          * segment count is [(# separators) + 1], and zero separators is ok.
 243          */
 244         if (*next_external_char) {
 245                 info->num_segments = 1;
 246                 for (i = 0; next_external_char[i]; i++) {
 247                         if (acpi_ns_valid_path_separator(next_external_char[i])) {
 248                                 info->num_segments++;
 249                         }
 250                 }
 251         }
 252
 253         info->length = (ACPI_NAME_SIZE * info->num_segments) +
 254             4 + info->num_carats;
 255
 256         info->next_external_char = next_external_char;
 257 }
 258
 259 /*******************************************************************************
 260  *
 261  * FUNCTION:    acpi_ns_build_internal_name
 262  *
 263  * PARAMETERS:  info            - Info struct fully initialized
 264  *
 265  * RETURN:      Status
 266  *
 267  * DESCRIPTION: Construct the internal (AML) namestring
 268  *              corresponding to the external (ASL) namestring.
 269  *
 270  ******************************************************************************/
 271
 272 acpi_status acpi_ns_build_internal_name(struct acpi_namestring_info *info)
 273 {
 274         u32 num_segments = info->num_segments;
 275         char *internal_name = info->internal_name;
 276         const char *external_name = info->next_external_char;
 277         char *result = NULL;
 278         u32 i;
 279
 280         ACPI_FUNCTION_TRACE(ns_build_internal_name);
 281
 282         /* Setup the correct prefixes, counts, and pointers */
 283
 284         if (info->fully_qualified) {
 285                 internal_name[0] = '\\';
 286
 287                 if (num_segments <= 1) {
 288                         result = &internal_name[1];
 289                 } else if (num_segments == 2) {
 290                         internal_name[1] = AML_DUAL_NAME_PREFIX;
 291                         result = &internal_name[2];
 292                 } else {
 293                         internal_name[1] = AML_MULTI_NAME_PREFIX_OP;
 294                         internal_name[2] = (char)num_segments;
 295                         result = &internal_name[3];
 296                 }
 297         } else {
 298                 /*
 299                  * Not fully qualified.
 300                  * Handle Carats first, then append the name segments
 301                  */
 302                 i = 0;
 303                 if (info->num_carats) {
 304                         for (i = 0; i < info->num_carats; i++) {
 305                                 internal_name[i] = '^';
 306                         }
 307                 }
 308
 309                 if (num_segments <= 1) {
 310                         result = &internal_name[i];
 311                 } else if (num_segments == 2) {
 312                         internal_name[i] = AML_DUAL_NAME_PREFIX;
 313                         result = &internal_name[(acpi_size) i + 1];
 314                 } else {
 315                         internal_name[i] = AML_MULTI_NAME_PREFIX_OP;
 316                         internal_name[(acpi_size) i + 1] = (char)num_segments;
 317                         result = &internal_name[(acpi_size) i + 2];
 318                 }
 319         }
 320
 321         /* Build the name (minus path separators) */
 322
 323         for (; num_segments; num_segments--) {
 324                 for (i = 0; i < ACPI_NAME_SIZE; i++) {
 325                         if (acpi_ns_valid_path_separator(*external_name) ||
 326                             (*external_name == 0)) {
 327
 328                                 /* Pad the segment with underscore(s) if segment is short */
 329
 330                                 result[i] = '_';
 331                         } else {
 332                                 /* Convert the character to uppercase and save it */
 333
 334                                 result[i] =
 335                                     (char)ACPI_TOUPPER((int)*external_name);
 336                                 external_name++;
 337                         }
 338                 }
 339
 340                 /* Now we must have a path separator, or the pathname is bad */
 341
 342                 if (!acpi_ns_valid_path_separator(*external_name) &&
 343                     (*external_name != 0)) {
 344                         return_ACPI_STATUS(AE_BAD_PATHNAME);
 345                 }
 346
 347                 /* Move on the next segment */
 348
 349                 external_name++;
 350                 result += ACPI_NAME_SIZE;
 351         }
 352
 353         /* Terminate the string */
 354
 355         *result = 0;
 356
 357         if (info->fully_qualified) {
 358                 ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
 359                                   "Returning [%p] (abs) \"\\%s\"\n",
 360                                   internal_name, internal_name));
 361         } else {
 362                 ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "Returning [%p] (rel) \"%s\"\n",
 363                                   internal_name, internal_name));
 364         }
 365
 366         return_ACPI_STATUS(AE_OK);
 367 }
 368
 369 /*******************************************************************************
 370  *
 371  * FUNCTION:    acpi_ns_internalize_name
 372  *
 373  * PARAMETERS:  *external_name          - External representation of name
 374  *              **Converted name        - Where to return the resulting
 375  *                                        internal represention of the name
 376  *
 377  * RETURN:      Status
 378  *
 379  * DESCRIPTION: Convert an external representation (e.g. "\_PR_.CPU0")
 380  *              to internal form (e.g. 5c 2f 02 5f 50 52 5f 43 50 55 30)
 381  *
 382  *******************************************************************************/
 383
 384 acpi_status
 385 acpi_ns_internalize_name(const char *external_name, char **converted_name)
 386 {
 387         char *internal_name;
 388         struct acpi_namestring_info info;
 389         acpi_status status;
 390
 391         ACPI_FUNCTION_TRACE(ns_internalize_name);
 392
 393         if ((!external_name) || (*external_name == 0) || (!converted_name)) {
 394                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 395         }
 396
 397         /* Get the length of the new internal name */
 398
 399         info.external_name = external_name;
 400         acpi_ns_get_internal_name_length(&info);
 401
 402         /* We need a segment to store the internal  name */
 403
 404         internal_name = ACPI_ALLOCATE_ZEROED(info.length);
 405         if (!internal_name) {
 406                 return_ACPI_STATUS(AE_NO_MEMORY);
 407         }
 408
 409         /* Build the name */
 410
 411         info.internal_name = internal_name;
 412         status = acpi_ns_build_internal_name(&info);
 413         if (ACPI_FAILURE(status)) {
 414                 ACPI_FREE(internal_name);
 415                 return_ACPI_STATUS(status);
 416         }
 417
 418         *converted_name = internal_name;
 419         return_ACPI_STATUS(AE_OK);
 420 }
 421
 422 /*******************************************************************************
 423  *
 424  * FUNCTION:    acpi_ns_externalize_name
 425  *
 426  * PARAMETERS:  internal_name_length - Lenth of the internal name below
 427  *              internal_name       - Internal representation of name
 428  *              converted_name_length - Where the length is returned
 429  *              converted_name      - Where the resulting external name
 430  *                                    is returned
 431  *
 432  * RETURN:      Status
 433  *
 434  * DESCRIPTION: Convert internal name (e.g. 5c 2f 02 5f 50 52 5f 43 50 55 30)
 435  *              to its external (printable) form (e.g. "\_PR_.CPU0")
 436  *
 437  ******************************************************************************/
 438
 439 acpi_status
 440 acpi_ns_externalize_name(u32 internal_name_length,
 441                          const char *internal_name,
 442                          u32 * converted_name_length, char **converted_name)
 443 {
 444         u32 names_index = 0;
 445         u32 num_segments = 0;
 446         u32 required_length;
 447         u32 prefix_length = 0;
 448         u32 i = 0;
 449         u32 j = 0;
 450
 451         ACPI_FUNCTION_TRACE(ns_externalize_name);
 452
 453         if (!internal_name_length || !internal_name || !converted_name) {
 454                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 455         }
 456
 457         /* Check for a prefix (one '\' | one or more '^') */
 458
 459         switch (internal_name[0]) {
 460         case '\\':
 461                 prefix_length = 1;
 462                 break;
 463
 464         case '^':
 465                 for (i = 0; i < internal_name_length; i++) {
 466                         if (internal_name[i] == '^') {
 467                                 prefix_length = i + 1;
 468                         } else {
 469                                 break;
 470                         }
 471                 }
 472
 473                 if (i == internal_name_length) {
 474                         prefix_length = i;
 475                 }
 476
 477                 break;
 478
 479         default:
 480                 break;
 481         }
 482
 483         /*
 484          * Check for object names. Note that there could be 0-255 of these
 485          * 4-byte elements.
 486          */
 487         if (prefix_length < internal_name_length) {
 488                 switch (internal_name[prefix_length]) {
 489                 case AML_MULTI_NAME_PREFIX_OP:
 490
 491                         /* <count> 4-byte names */
 492
 493                         names_index = prefix_length + 2;
 494                         num_segments = (u8)
 495                             internal_name[(acpi_size) prefix_length + 1];
 496                         break;
 497
 498                 case AML_DUAL_NAME_PREFIX:
 499
 500                         /* Two 4-byte names */
 501
 502                         names_index = prefix_length + 1;
 503                         num_segments = 2;
 504                         break;
 505
 506                 case 0:
 507
 508                         /* null_name */
 509
 510                         names_index = 0;
 511                         num_segments = 0;
 512                         break;
 513
 514                 default:
 515
 516                         /* one 4-byte name */
 517
 518                         names_index = prefix_length;
 519                         num_segments = 1;
 520                         break;
 521                 }
 522         }
 523
 524         /*
 525          * Calculate the length of converted_name, which equals the length
 526          * of the prefix, length of all object names, length of any required
 527          * punctuation ('.') between object names, plus the NULL terminator.
 528          */
 529         required_length = prefix_length + (4 * num_segments) +
 530             ((num_segments > 0) ? (num_segments - 1) : 0) + 1;
 531
 532         /*
 533          * Check to see if we're still in bounds. If not, there's a problem
 534          * with internal_name (invalid format).
 535          */
 536         if (required_length > internal_name_length) {
 537                 ACPI_ERROR((AE_INFO, "Invalid internal name"));
 538                 return_ACPI_STATUS(AE_BAD_PATHNAME);
 539         }
 540
 541         /* Build the converted_name */
 542
 543         *converted_name = ACPI_ALLOCATE_ZEROED(required_length);
 544         if (!(*converted_name)) {
 545                 return_ACPI_STATUS(AE_NO_MEMORY);
 546         }
 547
 548         j = 0;
 549
 550         for (i = 0; i < prefix_length; i++) {
 551                 (*converted_name)[j++] = internal_name[i];
 552         }
 553
 554         if (num_segments > 0) {
 555                 for (i = 0; i < num_segments; i++) {
 556                         if (i > 0) {
 557                                 (*converted_name)[j++] = '.';
 558                         }
 559
 560                         (*converted_name)[j++] = internal_name[names_index++];
 561                         (*converted_name)[j++] = internal_name[names_index++];
 562                         (*converted_name)[j++] = internal_name[names_index++];
 563                         (*converted_name)[j++] = internal_name[names_index++];
 564                 }
 565         }
 566
 567         if (converted_name_length) {
 568                 *converted_name_length = (u32) required_length;
 569         }
 570
 571         return_ACPI_STATUS(AE_OK);
 572 }
 573
 574 /*******************************************************************************
 575  *
 576  * FUNCTION:    acpi_ns_validate_handle
 577  *
 578  * PARAMETERS:  handle          - Handle to be validated and typecast to a
 579  *                                namespace node.
 580  *
 581  * RETURN:      A pointer to a namespace node
 582  *
 583  * DESCRIPTION: Convert a namespace handle to a namespace node. Handles special
 584  *              cases for the root node.
 585  *
 586  * NOTE: Real integer handles would allow for more verification
 587  *       and keep all pointers within this subsystem - however this introduces
 588  *       more overhead and has not been necessary to this point. Drivers
 589  *       holding handles are typically notified before a node becomes invalid
 590  *       due to a table unload.
 591  *
 592  ******************************************************************************/
 593
 594 struct acpi_namespace_node *acpi_ns_validate_handle(acpi_handle handle)
 595 {
 596
 597         ACPI_FUNCTION_ENTRY();
 598
 599         /* Parameter validation */
 600
 601         if ((!handle) || (handle == ACPI_ROOT_OBJECT)) {
 602                 return (acpi_gbl_root_node);
 603         }
 604
 605         /* We can at least attempt to verify the handle */
 606
 607         if (ACPI_GET_DESCRIPTOR_TYPE(handle) != ACPI_DESC_TYPE_NAMED) {
 608                 return (NULL);
 609         }
 610
 611         return (ACPI_CAST_PTR(struct acpi_namespace_node, handle));
 612 }
 613
 614 /*******************************************************************************
 615  *
 616  * FUNCTION:    acpi_ns_terminate
 617  *
 618  * PARAMETERS:  none
 619  *
 620  * RETURN:      none
 621  *
 622  * DESCRIPTION: free memory allocated for namespace and ACPI table storage.
 623  *
 624  ******************************************************************************/
 625
 626 void acpi_ns_terminate(void)
 627 {
 628         union acpi_operand_object *obj_desc;
 629
 630         ACPI_FUNCTION_TRACE(ns_terminate);
 631
 632         /*
 633          * 1) Free the entire namespace -- all nodes and objects
 634          *
 635          * Delete all object descriptors attached to namepsace nodes
 636          */
 637         acpi_ns_delete_namespace_subtree(acpi_gbl_root_node);
 638
 639         /* Detach any objects attached to the root */
 640
 641         obj_desc = acpi_ns_get_attached_object(acpi_gbl_root_node);
 642         if (obj_desc) {
 643                 acpi_ns_detach_object(acpi_gbl_root_node);
 644         }
 645
 646         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Namespace freed\n"));
 647         return_VOID;
 648 }
 649
 650 /*******************************************************************************
 651  *
 652  * FUNCTION:    acpi_ns_opens_scope
 653  *
 654  * PARAMETERS:  type        - A valid namespace type
 655  *
 656  * RETURN:      NEWSCOPE if the passed type "opens a name scope" according
 657  *              to the ACPI specification, else 0
 658  *
 659  ******************************************************************************/
 660
 661 u32 acpi_ns_opens_scope(acpi_object_type type)
 662 {
 663         ACPI_FUNCTION_TRACE_STR(ns_opens_scope, acpi_ut_get_type_name(type));
 664
 665         if (!acpi_ut_valid_object_type(type)) {
 666
 667                 /* type code out of range  */
 668
 669                 ACPI_WARNING((AE_INFO, "Invalid Object Type 0x%X", type));
 670                 return_UINT32(ACPI_NS_NORMAL);
 671         }
 672
 673         return_UINT32(((u32) acpi_gbl_ns_properties[type]) & ACPI_NS_NEWSCOPE);
 674 }
 675
 676 /*******************************************************************************
 677  *
 678  * FUNCTION:    acpi_ns_get_node
 679  *
 680  * PARAMETERS:  *pathname   - Name to be found, in external (ASL) format. The
 681  *                            \ (backslash) and ^ (carat) prefixes, and the
 682  *                            . (period) to separate segments are supported.
 683  *              prefix_node  - Root of subtree to be searched, or NS_ALL for the
 684  *                            root of the name space. If Name is fully
 685  *                            qualified (first s8 is '\'), the passed value
 686  *                            of Scope will not be accessed.
 687  *              flags       - Used to indicate whether to perform upsearch or
 688  *                            not.
 689  *              return_node - Where the Node is returned
 690  *
 691  * DESCRIPTION: Look up a name relative to a given scope and return the
 692  *              corresponding Node. NOTE: Scope can be null.
 693  *
 694  * MUTEX:       Locks namespace
 695  *
 696  ******************************************************************************/
 697
 698 acpi_status
 699 acpi_ns_get_node(struct acpi_namespace_node *prefix_node,
 700                  const char *pathname,
 701                  u32 flags, struct acpi_namespace_node **return_node)
 702 {
 703         union acpi_generic_state scope_info;
 704         acpi_status status;
 705         char *internal_path;
 706
 707         ACPI_FUNCTION_TRACE_PTR(ns_get_node, ACPI_CAST_PTR(char, pathname));
 708
 709         if (!pathname) {
 710                 *return_node = prefix_node;
 711                 if (!prefix_node) {
 712                         *return_node = acpi_gbl_root_node;
 713                 }
 714                 return_ACPI_STATUS(AE_OK);
 715         }
 716
 717         /* Convert path to internal representation */
 718
 719         status = acpi_ns_internalize_name(pathname, &internal_path);
 720         if (ACPI_FAILURE(status)) {
 721                 return_ACPI_STATUS(status);
 722         }
 723
 724         /* Must lock namespace during lookup */
 725
 726         status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
 727         if (ACPI_FAILURE(status)) {
 728                 goto cleanup;
 729         }
 730
 731         /* Setup lookup scope (search starting point) */
 732
 733         scope_info.scope.node = prefix_node;
 734
 735         /* Lookup the name in the namespace */
 736
 737         status = acpi_ns_lookup(&scope_info, internal_path, ACPI_TYPE_ANY,
 738                                 ACPI_IMODE_EXECUTE,
 739                                 (flags | ACPI_NS_DONT_OPEN_SCOPE), NULL,
 740                                 return_node);
 741         if (ACPI_FAILURE(status)) {
 742                 ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "%s, %s\n",
 743                                   pathname, acpi_format_exception(status)));
 744         }
 745
 746         (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
 747
 748       cleanup:
 749         ACPI_FREE(internal_path);
 750         return_ACPI_STATUS(status);
 751 }