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 - 2015, 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
  50 #define _COMPONENT          ACPI_NAMESPACE
  51 ACPI_MODULE_NAME("nsutils")
  52
  53 /* Local prototypes */
  54 #ifdef ACPI_OBSOLETE_FUNCTIONS
  55 acpi_name acpi_ns_find_parent_name(struct acpi_namespace_node *node_to_search);
  56 #endif
  57
  58 /*******************************************************************************
  59  *
  60  * FUNCTION:    acpi_ns_print_node_pathname
  61  *
  62  * PARAMETERS:  node            - Object
  63  *              message         - Prefix message
  64  *
  65  * DESCRIPTION: Print an object's full namespace pathname
  66  *              Manages allocation/freeing of a pathname buffer
  67  *
  68  ******************************************************************************/
  69
  70 void
  71 acpi_ns_print_node_pathname(struct acpi_namespace_node *node,
  72                             const char *message)
  73 {
  74         struct acpi_buffer buffer;
  75         acpi_status status;
  76
  77         if (!node) {
  78                 acpi_os_printf("[NULL NAME]");
  79                 return;
  80         }
  81
  82         /* Convert handle to full pathname and print it (with supplied message) */
  83
  84         buffer.length = ACPI_ALLOCATE_LOCAL_BUFFER;
  85
  86         status = acpi_ns_handle_to_pathname(node, &buffer, TRUE);
  87         if (ACPI_SUCCESS(status)) {
  88                 if (message) {
  89                         acpi_os_printf("%s ", message);
  90                 }
  91
  92                 acpi_os_printf("[%s] (Node %p)", (char *)buffer.pointer, node);
  93                 ACPI_FREE(buffer.pointer);
  94         }
  95 }
  96
  97 /*******************************************************************************
  98  *
  99  * FUNCTION:    acpi_ns_get_type
 100  *
 101  * PARAMETERS:  node        - Parent Node to be examined
 102  *
 103  * RETURN:      Type field from Node whose handle is passed
 104  *
 105  * DESCRIPTION: Return the type of a Namespace node
 106  *
 107  ******************************************************************************/
 108
 109 acpi_object_type acpi_ns_get_type(struct acpi_namespace_node * node)
 110 {
 111         ACPI_FUNCTION_TRACE(ns_get_type);
 112
 113         if (!node) {
 114                 ACPI_WARNING((AE_INFO, "Null Node parameter"));
 115                 return_UINT8(ACPI_TYPE_ANY);
 116         }
 117
 118         return_UINT8(node->type);
 119 }
 120
 121 /*******************************************************************************
 122  *
 123  * FUNCTION:    acpi_ns_local
 124  *
 125  * PARAMETERS:  type        - A namespace object type
 126  *
 127  * RETURN:      LOCAL if names must be found locally in objects of the
 128  *              passed type, 0 if enclosing scopes should be searched
 129  *
 130  * DESCRIPTION: Returns scope rule for the given object type.
 131  *
 132  ******************************************************************************/
 133
 134 u32 acpi_ns_local(acpi_object_type type)
 135 {
 136         ACPI_FUNCTION_TRACE(ns_local);
 137
 138         if (!acpi_ut_valid_object_type(type)) {
 139
 140                 /* Type code out of range  */
 141
 142                 ACPI_WARNING((AE_INFO, "Invalid Object Type 0x%X", type));
 143                 return_UINT32(ACPI_NS_NORMAL);
 144         }
 145
 146         return_UINT32(acpi_gbl_ns_properties[type] & ACPI_NS_LOCAL);
 147 }
 148
 149 /*******************************************************************************
 150  *
 151  * FUNCTION:    acpi_ns_get_internal_name_length
 152  *
 153  * PARAMETERS:  info            - Info struct initialized with the
 154  *                                external name pointer.
 155  *
 156  * RETURN:      None
 157  *
 158  * DESCRIPTION: Calculate the length of the internal (AML) namestring
 159  *              corresponding to the external (ASL) namestring.
 160  *
 161  ******************************************************************************/
 162
 163 void acpi_ns_get_internal_name_length(struct acpi_namestring_info *info)
 164 {
 165         const char *next_external_char;
 166         u32 i;
 167
 168         ACPI_FUNCTION_ENTRY();
 169
 170         next_external_char = info->external_name;
 171         info->num_carats = 0;
 172         info->num_segments = 0;
 173         info->fully_qualified = FALSE;
 174
 175         /*
 176          * For the internal name, the required length is 4 bytes per segment, plus
 177          * 1 each for root_prefix, multi_name_prefix_op, segment count, trailing null
 178          * (which is not really needed, but no there's harm in putting it there)
 179          *
 180          * strlen() + 1 covers the first name_seg, which has no path separator
 181          */
 182         if (ACPI_IS_ROOT_PREFIX(*next_external_char)) {
 183                 info->fully_qualified = TRUE;
 184                 next_external_char++;
 185
 186                 /* Skip redundant root_prefix, like \\_SB.PCI0.SBRG.EC0 */
 187
 188                 while (ACPI_IS_ROOT_PREFIX(*next_external_char)) {
 189                         next_external_char++;
 190                 }
 191         } else {
 192                 /* Handle Carat prefixes */
 193
 194                 while (ACPI_IS_PARENT_PREFIX(*next_external_char)) {
 195                         info->num_carats++;
 196                         next_external_char++;
 197                 }
 198         }
 199
 200         /*
 201          * Determine the number of ACPI name "segments" by counting the number of
 202          * path separators within the string. Start with one segment since the
 203          * segment count is [(# separators) + 1], and zero separators is ok.
 204          */
 205         if (*next_external_char) {
 206                 info->num_segments = 1;
 207                 for (i = 0; next_external_char[i]; i++) {
 208                         if (ACPI_IS_PATH_SEPARATOR(next_external_char[i])) {
 209                                 info->num_segments++;
 210                         }
 211                 }
 212         }
 213
 214         info->length = (ACPI_NAME_SIZE * info->num_segments) +
 215             4 + info->num_carats;
 216
 217         info->next_external_char = next_external_char;
 218 }
 219
 220 /*******************************************************************************
 221  *
 222  * FUNCTION:    acpi_ns_build_internal_name
 223  *
 224  * PARAMETERS:  info            - Info struct fully initialized
 225  *
 226  * RETURN:      Status
 227  *
 228  * DESCRIPTION: Construct the internal (AML) namestring
 229  *              corresponding to the external (ASL) namestring.
 230  *
 231  ******************************************************************************/
 232
 233 acpi_status acpi_ns_build_internal_name(struct acpi_namestring_info *info)
 234 {
 235         u32 num_segments = info->num_segments;
 236         char *internal_name = info->internal_name;
 237         const char *external_name = info->next_external_char;
 238         char *result = NULL;
 239         u32 i;
 240
 241         ACPI_FUNCTION_TRACE(ns_build_internal_name);
 242
 243         /* Setup the correct prefixes, counts, and pointers */
 244
 245         if (info->fully_qualified) {
 246                 internal_name[0] = AML_ROOT_PREFIX;
 247
 248                 if (num_segments <= 1) {
 249                         result = &internal_name[1];
 250                 } else if (num_segments == 2) {
 251                         internal_name[1] = AML_DUAL_NAME_PREFIX;
 252                         result = &internal_name[2];
 253                 } else {
 254                         internal_name[1] = AML_MULTI_NAME_PREFIX_OP;
 255                         internal_name[2] = (char)num_segments;
 256                         result = &internal_name[3];
 257                 }
 258         } else {
 259                 /*
 260                  * Not fully qualified.
 261                  * Handle Carats first, then append the name segments
 262                  */
 263                 i = 0;
 264                 if (info->num_carats) {
 265                         for (i = 0; i < info->num_carats; i++) {
 266                                 internal_name[i] = AML_PARENT_PREFIX;
 267                         }
 268                 }
 269
 270                 if (num_segments <= 1) {
 271                         result = &internal_name[i];
 272                 } else if (num_segments == 2) {
 273                         internal_name[i] = AML_DUAL_NAME_PREFIX;
 274                         result = &internal_name[(acpi_size) i + 1];
 275                 } else {
 276                         internal_name[i] = AML_MULTI_NAME_PREFIX_OP;
 277                         internal_name[(acpi_size) i + 1] = (char)num_segments;
 278                         result = &internal_name[(acpi_size) i + 2];
 279                 }
 280         }
 281
 282         /* Build the name (minus path separators) */
 283
 284         for (; num_segments; num_segments--) {
 285                 for (i = 0; i < ACPI_NAME_SIZE; i++) {
 286                         if (ACPI_IS_PATH_SEPARATOR(*external_name) ||
 287                             (*external_name == 0)) {
 288
 289                                 /* Pad the segment with underscore(s) if segment is short */
 290
 291                                 result[i] = '_';
 292                         } else {
 293                                 /* Convert the character to uppercase and save it */
 294
 295                                 result[i] = (char)toupper((int)*external_name);
 296                                 external_name++;
 297                         }
 298                 }
 299
 300                 /* Now we must have a path separator, or the pathname is bad */
 301
 302                 if (!ACPI_IS_PATH_SEPARATOR(*external_name) &&
 303                     (*external_name != 0)) {
 304                         return_ACPI_STATUS(AE_BAD_PATHNAME);
 305                 }
 306
 307                 /* Move on the next segment */
 308
 309                 external_name++;
 310                 result += ACPI_NAME_SIZE;
 311         }
 312
 313         /* Terminate the string */
 314
 315         *result = 0;
 316
 317         if (info->fully_qualified) {
 318                 ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
 319                                   "Returning [%p] (abs) \"\\%s\"\n",
 320                                   internal_name, internal_name));
 321         } else {
 322                 ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "Returning [%p] (rel) \"%s\"\n",
 323                                   internal_name, internal_name));
 324         }
 325
 326         return_ACPI_STATUS(AE_OK);
 327 }
 328
 329 /*******************************************************************************
 330  *
 331  * FUNCTION:    acpi_ns_internalize_name
 332  *
 333  * PARAMETERS:  *external_name          - External representation of name
 334  *              **Converted name        - Where to return the resulting
 335  *                                        internal represention of the name
 336  *
 337  * RETURN:      Status
 338  *
 339  * DESCRIPTION: Convert an external representation (e.g. "\_PR_.CPU0")
 340  *              to internal form (e.g. 5c 2f 02 5f 50 52 5f 43 50 55 30)
 341  *
 342  *******************************************************************************/
 343
 344 acpi_status
 345 acpi_ns_internalize_name(const char *external_name, char **converted_name)
 346 {
 347         char *internal_name;
 348         struct acpi_namestring_info info;
 349         acpi_status status;
 350
 351         ACPI_FUNCTION_TRACE(ns_internalize_name);
 352
 353         if ((!external_name) || (*external_name == 0) || (!converted_name)) {
 354                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 355         }
 356
 357         /* Get the length of the new internal name */
 358
 359         info.external_name = external_name;
 360         acpi_ns_get_internal_name_length(&info);
 361
 362         /* We need a segment to store the internal  name */
 363
 364         internal_name = ACPI_ALLOCATE_ZEROED(info.length);
 365         if (!internal_name) {
 366                 return_ACPI_STATUS(AE_NO_MEMORY);
 367         }
 368
 369         /* Build the name */
 370
 371         info.internal_name = internal_name;
 372         status = acpi_ns_build_internal_name(&info);
 373         if (ACPI_FAILURE(status)) {
 374                 ACPI_FREE(internal_name);
 375                 return_ACPI_STATUS(status);
 376         }
 377
 378         *converted_name = internal_name;
 379         return_ACPI_STATUS(AE_OK);
 380 }
 381
 382 /*******************************************************************************
 383  *
 384  * FUNCTION:    acpi_ns_externalize_name
 385  *
 386  * PARAMETERS:  internal_name_length - Lenth of the internal name below
 387  *              internal_name       - Internal representation of name
 388  *              converted_name_length - Where the length is returned
 389  *              converted_name      - Where the resulting external name
 390  *                                    is returned
 391  *
 392  * RETURN:      Status
 393  *
 394  * DESCRIPTION: Convert internal name (e.g. 5c 2f 02 5f 50 52 5f 43 50 55 30)
 395  *              to its external (printable) form (e.g. "\_PR_.CPU0")
 396  *
 397  ******************************************************************************/
 398
 399 acpi_status
 400 acpi_ns_externalize_name(u32 internal_name_length,
 401                          const char *internal_name,
 402                          u32 * converted_name_length, char **converted_name)
 403 {
 404         u32 names_index = 0;
 405         u32 num_segments = 0;
 406         u32 required_length;
 407         u32 prefix_length = 0;
 408         u32 i = 0;
 409         u32 j = 0;
 410
 411         ACPI_FUNCTION_TRACE(ns_externalize_name);
 412
 413         if (!internal_name_length || !internal_name || !converted_name) {
 414                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 415         }
 416
 417         /* Check for a prefix (one '\' | one or more '^') */
 418
 419         switch (internal_name[0]) {
 420         case AML_ROOT_PREFIX:
 421
 422                 prefix_length = 1;
 423                 break;
 424
 425         case AML_PARENT_PREFIX:
 426
 427                 for (i = 0; i < internal_name_length; i++) {
 428                         if (ACPI_IS_PARENT_PREFIX(internal_name[i])) {
 429                                 prefix_length = i + 1;
 430                         } else {
 431                                 break;
 432                         }
 433                 }
 434
 435                 if (i == internal_name_length) {
 436                         prefix_length = i;
 437                 }
 438
 439                 break;
 440
 441         default:
 442
 443                 break;
 444         }
 445
 446         /*
 447          * Check for object names. Note that there could be 0-255 of these
 448          * 4-byte elements.
 449          */
 450         if (prefix_length < internal_name_length) {
 451                 switch (internal_name[prefix_length]) {
 452                 case AML_MULTI_NAME_PREFIX_OP:
 453
 454                         /* <count> 4-byte names */
 455
 456                         names_index = prefix_length + 2;
 457                         num_segments = (u8)
 458                             internal_name[(acpi_size) prefix_length + 1];
 459                         break;
 460
 461                 case AML_DUAL_NAME_PREFIX:
 462
 463                         /* Two 4-byte names */
 464
 465                         names_index = prefix_length + 1;
 466                         num_segments = 2;
 467                         break;
 468
 469                 case 0:
 470
 471                         /* null_name */
 472
 473                         names_index = 0;
 474                         num_segments = 0;
 475                         break;
 476
 477                 default:
 478
 479                         /* one 4-byte name */
 480
 481                         names_index = prefix_length;
 482                         num_segments = 1;
 483                         break;
 484                 }
 485         }
 486
 487         /*
 488          * Calculate the length of converted_name, which equals the length
 489          * of the prefix, length of all object names, length of any required
 490          * punctuation ('.') between object names, plus the NULL terminator.
 491          */
 492         required_length = prefix_length + (4 * num_segments) +
 493             ((num_segments > 0) ? (num_segments - 1) : 0) + 1;
 494
 495         /*
 496          * Check to see if we're still in bounds. If not, there's a problem
 497          * with internal_name (invalid format).
 498          */
 499         if (required_length > internal_name_length) {
 500                 ACPI_ERROR((AE_INFO, "Invalid internal name"));
 501                 return_ACPI_STATUS(AE_BAD_PATHNAME);
 502         }
 503
 504         /* Build the converted_name */
 505
 506         *converted_name = ACPI_ALLOCATE_ZEROED(required_length);
 507         if (!(*converted_name)) {
 508                 return_ACPI_STATUS(AE_NO_MEMORY);
 509         }
 510
 511         j = 0;
 512
 513         for (i = 0; i < prefix_length; i++) {
 514                 (*converted_name)[j++] = internal_name[i];
 515         }
 516
 517         if (num_segments > 0) {
 518                 for (i = 0; i < num_segments; i++) {
 519                         if (i > 0) {
 520                                 (*converted_name)[j++] = '.';
 521                         }
 522
 523                         /* Copy and validate the 4-char name segment */
 524
 525                         ACPI_MOVE_NAME(&(*converted_name)[j],
 526                                        &internal_name[names_index]);
 527                         acpi_ut_repair_name(&(*converted_name)[j]);
 528
 529                         j += ACPI_NAME_SIZE;
 530                         names_index += ACPI_NAME_SIZE;
 531                 }
 532         }
 533
 534         if (converted_name_length) {
 535                 *converted_name_length = (u32) required_length;
 536         }
 537
 538         return_ACPI_STATUS(AE_OK);
 539 }
 540
 541 /*******************************************************************************
 542  *
 543  * FUNCTION:    acpi_ns_validate_handle
 544  *
 545  * PARAMETERS:  handle          - Handle to be validated and typecast to a
 546  *                                namespace node.
 547  *
 548  * RETURN:      A pointer to a namespace node
 549  *
 550  * DESCRIPTION: Convert a namespace handle to a namespace node. Handles special
 551  *              cases for the root node.
 552  *
 553  * NOTE: Real integer handles would allow for more verification
 554  *       and keep all pointers within this subsystem - however this introduces
 555  *       more overhead and has not been necessary to this point. Drivers
 556  *       holding handles are typically notified before a node becomes invalid
 557  *       due to a table unload.
 558  *
 559  ******************************************************************************/
 560
 561 struct acpi_namespace_node *acpi_ns_validate_handle(acpi_handle handle)
 562 {
 563
 564         ACPI_FUNCTION_ENTRY();
 565
 566         /* Parameter validation */
 567
 568         if ((!handle) || (handle == ACPI_ROOT_OBJECT)) {
 569                 return (acpi_gbl_root_node);
 570         }
 571
 572         /* We can at least attempt to verify the handle */
 573
 574         if (ACPI_GET_DESCRIPTOR_TYPE(handle) != ACPI_DESC_TYPE_NAMED) {
 575                 return (NULL);
 576         }
 577
 578         return (ACPI_CAST_PTR(struct acpi_namespace_node, handle));
 579 }
 580
 581 /*******************************************************************************
 582  *
 583  * FUNCTION:    acpi_ns_terminate
 584  *
 585  * PARAMETERS:  none
 586  *
 587  * RETURN:      none
 588  *
 589  * DESCRIPTION: free memory allocated for namespace and ACPI table storage.
 590  *
 591  ******************************************************************************/
 592
 593 void acpi_ns_terminate(void)
 594 {
 595         acpi_status status;
 596
 597         ACPI_FUNCTION_TRACE(ns_terminate);
 598
 599 #ifdef ACPI_EXEC_APP
 600         {
 601                 union acpi_operand_object *prev;
 602                 union acpi_operand_object *next;
 603
 604                 /* Delete any module-level code blocks */
 605
 606                 next = acpi_gbl_module_code_list;
 607                 while (next) {
 608                         prev = next;
 609                         next = next->method.mutex;
 610                         prev->method.mutex = NULL;      /* Clear the Mutex (cheated) field */
 611                         acpi_ut_remove_reference(prev);
 612                 }
 613         }
 614 #endif
 615
 616         /*
 617          * Free the entire namespace -- all nodes and all objects
 618          * attached to the nodes
 619          */
 620         acpi_ns_delete_namespace_subtree(acpi_gbl_root_node);
 621
 622         /* Delete any objects attached to the root node */
 623
 624         status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
 625         if (ACPI_FAILURE(status)) {
 626                 return_VOID;
 627         }
 628
 629         acpi_ns_delete_node(acpi_gbl_root_node);
 630         (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
 631
 632         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Namespace freed\n"));
 633         return_VOID;
 634 }
 635
 636 /*******************************************************************************
 637  *
 638  * FUNCTION:    acpi_ns_opens_scope
 639  *
 640  * PARAMETERS:  type        - A valid namespace type
 641  *
 642  * RETURN:      NEWSCOPE if the passed type "opens a name scope" according
 643  *              to the ACPI specification, else 0
 644  *
 645  ******************************************************************************/
 646
 647 u32 acpi_ns_opens_scope(acpi_object_type type)
 648 {
 649         ACPI_FUNCTION_ENTRY();
 650
 651         if (type > ACPI_TYPE_LOCAL_MAX) {
 652
 653                 /* type code out of range  */
 654
 655                 ACPI_WARNING((AE_INFO, "Invalid Object Type 0x%X", type));
 656                 return (ACPI_NS_NORMAL);
 657         }
 658
 659         return (((u32)acpi_gbl_ns_properties[type]) & ACPI_NS_NEWSCOPE);
 660 }
 661
 662 /*******************************************************************************
 663  *
 664  * FUNCTION:    acpi_ns_get_node
 665  *
 666  * PARAMETERS:  *pathname   - Name to be found, in external (ASL) format. The
 667  *                            \ (backslash) and ^ (carat) prefixes, and the
 668  *                            . (period) to separate segments are supported.
 669  *              prefix_node  - Root of subtree to be searched, or NS_ALL for the
 670  *                            root of the name space. If Name is fully
 671  *                            qualified (first s8 is '\'), the passed value
 672  *                            of Scope will not be accessed.
 673  *              flags       - Used to indicate whether to perform upsearch or
 674  *                            not.
 675  *              return_node - Where the Node is returned
 676  *
 677  * DESCRIPTION: Look up a name relative to a given scope and return the
 678  *              corresponding Node. NOTE: Scope can be null.
 679  *
 680  * MUTEX:       Locks namespace
 681  *
 682  ******************************************************************************/
 683
 684 acpi_status
 685 acpi_ns_get_node(struct acpi_namespace_node *prefix_node,
 686                  const char *pathname,
 687                  u32 flags, struct acpi_namespace_node **return_node)
 688 {
 689         union acpi_generic_state scope_info;
 690         acpi_status status;
 691         char *internal_path;
 692
 693         ACPI_FUNCTION_TRACE_PTR(ns_get_node, ACPI_CAST_PTR(char, pathname));
 694
 695         /* Simplest case is a null pathname */
 696
 697         if (!pathname) {
 698                 *return_node = prefix_node;
 699                 if (!prefix_node) {
 700                         *return_node = acpi_gbl_root_node;
 701                 }
 702                 return_ACPI_STATUS(AE_OK);
 703         }
 704
 705         /* Quick check for a reference to the root */
 706
 707         if (ACPI_IS_ROOT_PREFIX(pathname[0]) && (!pathname[1])) {
 708                 *return_node = acpi_gbl_root_node;
 709                 return_ACPI_STATUS(AE_OK);
 710         }
 711
 712         /* Convert path to internal representation */
 713
 714         status = acpi_ns_internalize_name(pathname, &internal_path);
 715         if (ACPI_FAILURE(status)) {
 716                 return_ACPI_STATUS(status);
 717         }
 718
 719         /* Must lock namespace during lookup */
 720
 721         status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
 722         if (ACPI_FAILURE(status)) {
 723                 goto cleanup;
 724         }
 725
 726         /* Setup lookup scope (search starting point) */
 727
 728         scope_info.scope.node = prefix_node;
 729
 730         /* Lookup the name in the namespace */
 731
 732         status = acpi_ns_lookup(&scope_info, internal_path, ACPI_TYPE_ANY,
 733                                 ACPI_IMODE_EXECUTE,
 734                                 (flags | ACPI_NS_DONT_OPEN_SCOPE), NULL,
 735                                 return_node);
 736         if (ACPI_FAILURE(status)) {
 737                 ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "%s, %s\n",
 738                                   pathname, acpi_format_exception(status)));
 739         }
 740
 741         (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
 742
 743 cleanup:
 744         ACPI_FREE(internal_path);
 745         return_ACPI_STATUS(status);
 746 }