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 - 2017, 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,
 177          * plus 1 each for root_prefix, multi_name_prefix_op, segment count,
 178          * trailing null (which is not really needed, but no there's harm in
 179          * putting it there)
 180          *
 181          * strlen() + 1 covers the first name_seg, which has no path separator
 182          */
 183         if (ACPI_IS_ROOT_PREFIX(*next_external_char)) {
 184                 info->fully_qualified = TRUE;
 185                 next_external_char++;
 186
 187                 /* Skip redundant root_prefix, like \\_SB.PCI0.SBRG.EC0 */
 188
 189                 while (ACPI_IS_ROOT_PREFIX(*next_external_char)) {
 190                         next_external_char++;
 191                 }
 192         } else {
 193                 /* Handle Carat prefixes */
 194
 195                 while (ACPI_IS_PARENT_PREFIX(*next_external_char)) {
 196                         info->num_carats++;
 197                         next_external_char++;
 198                 }
 199         }
 200
 201         /*
 202          * Determine the number of ACPI name "segments" by counting the number of
 203          * path separators within the string. Start with one segment since the
 204          * segment count is [(# separators) + 1], and zero separators is ok.
 205          */
 206         if (*next_external_char) {
 207                 info->num_segments = 1;
 208                 for (i = 0; next_external_char[i]; i++) {
 209                         if (ACPI_IS_PATH_SEPARATOR(next_external_char[i])) {
 210                                 info->num_segments++;
 211                         }
 212                 }
 213         }
 214
 215         info->length = (ACPI_NAME_SIZE * info->num_segments) +
 216             4 + info->num_carats;
 217
 218         info->next_external_char = next_external_char;
 219 }
 220
 221 /*******************************************************************************
 222  *
 223  * FUNCTION:    acpi_ns_build_internal_name
 224  *
 225  * PARAMETERS:  info            - Info struct fully initialized
 226  *
 227  * RETURN:      Status
 228  *
 229  * DESCRIPTION: Construct the internal (AML) namestring
 230  *              corresponding to the external (ASL) namestring.
 231  *
 232  ******************************************************************************/
 233
 234 acpi_status acpi_ns_build_internal_name(struct acpi_namestring_info *info)
 235 {
 236         u32 num_segments = info->num_segments;
 237         char *internal_name = info->internal_name;
 238         const char *external_name = info->next_external_char;
 239         char *result = NULL;
 240         u32 i;
 241
 242         ACPI_FUNCTION_TRACE(ns_build_internal_name);
 243
 244         /* Setup the correct prefixes, counts, and pointers */
 245
 246         if (info->fully_qualified) {
 247                 internal_name[0] = AML_ROOT_PREFIX;
 248
 249                 if (num_segments <= 1) {
 250                         result = &internal_name[1];
 251                 } else if (num_segments == 2) {
 252                         internal_name[1] = AML_DUAL_NAME_PREFIX;
 253                         result = &internal_name[2];
 254                 } else {
 255                         internal_name[1] = AML_MULTI_NAME_PREFIX;
 256                         internal_name[2] = (char)num_segments;
 257                         result = &internal_name[3];
 258                 }
 259         } else {
 260                 /*
 261                  * Not fully qualified.
 262                  * Handle Carats first, then append the name segments
 263                  */
 264                 i = 0;
 265                 if (info->num_carats) {
 266                         for (i = 0; i < info->num_carats; i++) {
 267                                 internal_name[i] = AML_PARENT_PREFIX;
 268                         }
 269                 }
 270
 271                 if (num_segments <= 1) {
 272                         result = &internal_name[i];
 273                 } else if (num_segments == 2) {
 274                         internal_name[i] = AML_DUAL_NAME_PREFIX;
 275                         result = &internal_name[(acpi_size)i + 1];
 276                 } else {
 277                         internal_name[i] = AML_MULTI_NAME_PREFIX;
 278                         internal_name[(acpi_size)i + 1] = (char)num_segments;
 279                         result = &internal_name[(acpi_size)i + 2];
 280                 }
 281         }
 282
 283         /* Build the name (minus path separators) */
 284
 285         for (; num_segments; num_segments--) {
 286                 for (i = 0; i < ACPI_NAME_SIZE; i++) {
 287                         if (ACPI_IS_PATH_SEPARATOR(*external_name) ||
 288                             (*external_name == 0)) {
 289
 290                                 /* Pad the segment with underscore(s) if segment is short */
 291
 292                                 result[i] = '_';
 293                         } else {
 294                                 /* Convert the character to uppercase and save it */
 295
 296                                 result[i] = (char)toupper((int)*external_name);
 297                                 external_name++;
 298                         }
 299                 }
 300
 301                 /* Now we must have a path separator, or the pathname is bad */
 302
 303                 if (!ACPI_IS_PATH_SEPARATOR(*external_name) &&
 304                     (*external_name != 0)) {
 305                         return_ACPI_STATUS(AE_BAD_PATHNAME);
 306                 }
 307
 308                 /* Move on the next segment */
 309
 310                 external_name++;
 311                 result += ACPI_NAME_SIZE;
 312         }
 313
 314         /* Terminate the string */
 315
 316         *result = 0;
 317
 318         if (info->fully_qualified) {
 319                 ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
 320                                   "Returning [%p] (abs) \"\\%s\"\n",
 321                                   internal_name, internal_name));
 322         } else {
 323                 ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "Returning [%p] (rel) \"%s\"\n",
 324                                   internal_name, internal_name));
 325         }
 326
 327         return_ACPI_STATUS(AE_OK);
 328 }
 329
 330 /*******************************************************************************
 331  *
 332  * FUNCTION:    acpi_ns_internalize_name
 333  *
 334  * PARAMETERS:  *external_name          - External representation of name
 335  *              **Converted name        - Where to return the resulting
 336  *                                        internal represention of the name
 337  *
 338  * RETURN:      Status
 339  *
 340  * DESCRIPTION: Convert an external representation (e.g. "\_PR_.CPU0")
 341  *              to internal form (e.g. 5c 2f 02 5f 50 52 5f 43 50 55 30)
 342  *
 343  *******************************************************************************/
 344
 345 acpi_status
 346 acpi_ns_internalize_name(const char *external_name, char **converted_name)
 347 {
 348         char *internal_name;
 349         struct acpi_namestring_info info;
 350         acpi_status status;
 351
 352         ACPI_FUNCTION_TRACE(ns_internalize_name);
 353
 354         if ((!external_name) || (*external_name == 0) || (!converted_name)) {
 355                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 356         }
 357
 358         /* Get the length of the new internal name */
 359
 360         info.external_name = external_name;
 361         acpi_ns_get_internal_name_length(&info);
 362
 363         /* We need a segment to store the internal  name */
 364
 365         internal_name = ACPI_ALLOCATE_ZEROED(info.length);
 366         if (!internal_name) {
 367                 return_ACPI_STATUS(AE_NO_MEMORY);
 368         }
 369
 370         /* Build the name */
 371
 372         info.internal_name = internal_name;
 373         status = acpi_ns_build_internal_name(&info);
 374         if (ACPI_FAILURE(status)) {
 375                 ACPI_FREE(internal_name);
 376                 return_ACPI_STATUS(status);
 377         }
 378
 379         *converted_name = internal_name;
 380         return_ACPI_STATUS(AE_OK);
 381 }
 382
 383 /*******************************************************************************
 384  *
 385  * FUNCTION:    acpi_ns_externalize_name
 386  *
 387  * PARAMETERS:  internal_name_length - Lenth of the internal name below
 388  *              internal_name       - Internal representation of name
 389  *              converted_name_length - Where the length is returned
 390  *              converted_name      - Where the resulting external name
 391  *                                    is returned
 392  *
 393  * RETURN:      Status
 394  *
 395  * DESCRIPTION: Convert internal name (e.g. 5c 2f 02 5f 50 52 5f 43 50 55 30)
 396  *              to its external (printable) form (e.g. "\_PR_.CPU0")
 397  *
 398  ******************************************************************************/
 399
 400 acpi_status
 401 acpi_ns_externalize_name(u32 internal_name_length,
 402                          const char *internal_name,
 403                          u32 * converted_name_length, char **converted_name)
 404 {
 405         u32 names_index = 0;
 406         u32 num_segments = 0;
 407         u32 required_length;
 408         u32 prefix_length = 0;
 409         u32 i = 0;
 410         u32 j = 0;
 411
 412         ACPI_FUNCTION_TRACE(ns_externalize_name);
 413
 414         if (!internal_name_length || !internal_name || !converted_name) {
 415                 return_ACPI_STATUS(AE_BAD_PARAMETER);
 416         }
 417
 418         /* Check for a prefix (one '\' | one or more '^') */
 419
 420         switch (internal_name[0]) {
 421         case AML_ROOT_PREFIX:
 422
 423                 prefix_length = 1;
 424                 break;
 425
 426         case AML_PARENT_PREFIX:
 427
 428                 for (i = 0; i < internal_name_length; i++) {
 429                         if (ACPI_IS_PARENT_PREFIX(internal_name[i])) {
 430                                 prefix_length = i + 1;
 431                         } else {
 432                                 break;
 433                         }
 434                 }
 435
 436                 if (i == internal_name_length) {
 437                         prefix_length = i;
 438                 }
 439
 440                 break;
 441
 442         default:
 443
 444                 break;
 445         }
 446
 447         /*
 448          * Check for object names. Note that there could be 0-255 of these
 449          * 4-byte elements.
 450          */
 451         if (prefix_length < internal_name_length) {
 452                 switch (internal_name[prefix_length]) {
 453                 case AML_MULTI_NAME_PREFIX:
 454
 455                         /* <count> 4-byte names */
 456
 457                         names_index = prefix_length + 2;
 458                         num_segments = (u8)
 459                             internal_name[(acpi_size)prefix_length + 1];
 460                         break;
 461
 462                 case AML_DUAL_NAME_PREFIX:
 463
 464                         /* Two 4-byte names */
 465
 466                         names_index = prefix_length + 1;
 467                         num_segments = 2;
 468                         break;
 469
 470                 case 0:
 471
 472                         /* null_name */
 473
 474                         names_index = 0;
 475                         num_segments = 0;
 476                         break;
 477
 478                 default:
 479
 480                         /* one 4-byte name */
 481
 482                         names_index = prefix_length;
 483                         num_segments = 1;
 484                         break;
 485                 }
 486         }
 487
 488         /*
 489          * Calculate the length of converted_name, which equals the length
 490          * of the prefix, length of all object names, length of any required
 491          * punctuation ('.') between object names, plus the NULL terminator.
 492          */
 493         required_length = prefix_length + (4 * num_segments) +
 494             ((num_segments > 0) ? (num_segments - 1) : 0) + 1;
 495
 496         /*
 497          * Check to see if we're still in bounds. If not, there's a problem
 498          * with internal_name (invalid format).
 499          */
 500         if (required_length > internal_name_length) {
 501                 ACPI_ERROR((AE_INFO, "Invalid internal name"));
 502                 return_ACPI_STATUS(AE_BAD_PATHNAME);
 503         }
 504
 505         /* Build the converted_name */
 506
 507         *converted_name = ACPI_ALLOCATE_ZEROED(required_length);
 508         if (!(*converted_name)) {
 509                 return_ACPI_STATUS(AE_NO_MEMORY);
 510         }
 511
 512         j = 0;
 513
 514         for (i = 0; i < prefix_length; i++) {
 515                 (*converted_name)[j++] = internal_name[i];
 516         }
 517
 518         if (num_segments > 0) {
 519                 for (i = 0; i < num_segments; i++) {
 520                         if (i > 0) {
 521                                 (*converted_name)[j++] = '.';
 522                         }
 523
 524                         /* Copy and validate the 4-char name segment */
 525
 526                         ACPI_MOVE_NAME(&(*converted_name)[j],
 527                                        &internal_name[names_index]);
 528                         acpi_ut_repair_name(&(*converted_name)[j]);
 529
 530                         j += ACPI_NAME_SIZE;
 531                         names_index += ACPI_NAME_SIZE;
 532                 }
 533         }
 534
 535         if (converted_name_length) {
 536                 *converted_name_length = (u32) required_length;
 537         }
 538
 539         return_ACPI_STATUS(AE_OK);
 540 }
 541
 542 /*******************************************************************************
 543  *
 544  * FUNCTION:    acpi_ns_validate_handle
 545  *
 546  * PARAMETERS:  handle          - Handle to be validated and typecast to a
 547  *                                namespace node.
 548  *
 549  * RETURN:      A pointer to a namespace node
 550  *
 551  * DESCRIPTION: Convert a namespace handle to a namespace node. Handles special
 552  *              cases for the root node.
 553  *
 554  * NOTE: Real integer handles would allow for more verification
 555  *       and keep all pointers within this subsystem - however this introduces
 556  *       more overhead and has not been necessary to this point. Drivers
 557  *       holding handles are typically notified before a node becomes invalid
 558  *       due to a table unload.
 559  *
 560  ******************************************************************************/
 561
 562 struct acpi_namespace_node *acpi_ns_validate_handle(acpi_handle handle)
 563 {
 564
 565         ACPI_FUNCTION_ENTRY();
 566
 567         /* Parameter validation */
 568
 569         if ((!handle) || (handle == ACPI_ROOT_OBJECT)) {
 570                 return (acpi_gbl_root_node);
 571         }
 572
 573         /* We can at least attempt to verify the handle */
 574
 575         if (ACPI_GET_DESCRIPTOR_TYPE(handle) != ACPI_DESC_TYPE_NAMED) {
 576                 return (NULL);
 577         }
 578
 579         return (ACPI_CAST_PTR(struct acpi_namespace_node, handle));
 580 }
 581
 582 /*******************************************************************************
 583  *
 584  * FUNCTION:    acpi_ns_terminate
 585  *
 586  * PARAMETERS:  none
 587  *
 588  * RETURN:      none
 589  *
 590  * DESCRIPTION: free memory allocated for namespace and ACPI table storage.
 591  *
 592  ******************************************************************************/
 593
 594 void acpi_ns_terminate(void)
 595 {
 596         acpi_status status;
 597         union acpi_operand_object *prev;
 598         union acpi_operand_object *next;
 599
 600         ACPI_FUNCTION_TRACE(ns_terminate);
 601
 602         /* Delete any module-level code blocks */
 603
 604         next = acpi_gbl_module_code_list;
 605         while (next) {
 606                 prev = next;
 607                 next = next->method.mutex;
 608                 prev->method.mutex = NULL;      /* Clear the Mutex (cheated) field */
 609                 acpi_ut_remove_reference(prev);
 610         }
 611
 612         /*
 613          * Free the entire namespace -- all nodes and all objects
 614          * attached to the nodes
 615          */
 616         acpi_ns_delete_namespace_subtree(acpi_gbl_root_node);
 617
 618         /* Delete any objects attached to the root node */
 619
 620         status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
 621         if (ACPI_FAILURE(status)) {
 622                 return_VOID;
 623         }
 624
 625         acpi_ns_delete_node(acpi_gbl_root_node);
 626         (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
 627
 628         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Namespace freed\n"));
 629         return_VOID;
 630 }
 631
 632 /*******************************************************************************
 633  *
 634  * FUNCTION:    acpi_ns_opens_scope
 635  *
 636  * PARAMETERS:  type        - A valid namespace type
 637  *
 638  * RETURN:      NEWSCOPE if the passed type "opens a name scope" according
 639  *              to the ACPI specification, else 0
 640  *
 641  ******************************************************************************/
 642
 643 u32 acpi_ns_opens_scope(acpi_object_type type)
 644 {
 645         ACPI_FUNCTION_ENTRY();
 646
 647         if (type > ACPI_TYPE_LOCAL_MAX) {
 648
 649                 /* type code out of range  */
 650
 651                 ACPI_WARNING((AE_INFO, "Invalid Object Type 0x%X", type));
 652                 return (ACPI_NS_NORMAL);
 653         }
 654
 655         return (((u32)acpi_gbl_ns_properties[type]) & ACPI_NS_NEWSCOPE);
 656 }
 657
 658 /*******************************************************************************
 659  *
 660  * FUNCTION:    acpi_ns_get_node_unlocked
 661  *
 662  * PARAMETERS:  *pathname   - Name to be found, in external (ASL) format. The
 663  *                            \ (backslash) and ^ (carat) prefixes, and the
 664  *                            . (period) to separate segments are supported.
 665  *              prefix_node  - Root of subtree to be searched, or NS_ALL for the
 666  *                            root of the name space. If Name is fully
 667  *                            qualified (first s8 is '\'), the passed value
 668  *                            of Scope will not be accessed.
 669  *              flags       - Used to indicate whether to perform upsearch or
 670  *                            not.
 671  *              return_node - Where the Node is returned
 672  *
 673  * DESCRIPTION: Look up a name relative to a given scope and return the
 674  *              corresponding Node. NOTE: Scope can be null.
 675  *
 676  * MUTEX:       Doesn't locks namespace
 677  *
 678  ******************************************************************************/
 679
 680 acpi_status
 681 acpi_ns_get_node_unlocked(struct acpi_namespace_node *prefix_node,
 682                           const char *pathname,
 683                           u32 flags, struct acpi_namespace_node **return_node)
 684 {
 685         union acpi_generic_state scope_info;
 686         acpi_status status;
 687         char *internal_path;
 688
 689         ACPI_FUNCTION_TRACE_PTR(ns_get_node_unlocked,
 690                                 ACPI_CAST_PTR(char, pathname));
 691
 692         /* Simplest case is a null pathname */
 693
 694         if (!pathname) {
 695                 *return_node = prefix_node;
 696                 if (!prefix_node) {
 697                         *return_node = acpi_gbl_root_node;
 698                 }
 699
 700                 return_ACPI_STATUS(AE_OK);
 701         }
 702
 703         /* Quick check for a reference to the root */
 704
 705         if (ACPI_IS_ROOT_PREFIX(pathname[0]) && (!pathname[1])) {
 706                 *return_node = acpi_gbl_root_node;
 707                 return_ACPI_STATUS(AE_OK);
 708         }
 709
 710         /* Convert path to internal representation */
 711
 712         status = acpi_ns_internalize_name(pathname, &internal_path);
 713         if (ACPI_FAILURE(status)) {
 714                 return_ACPI_STATUS(status);
 715         }
 716
 717         /* Setup lookup scope (search starting point) */
 718
 719         scope_info.scope.node = prefix_node;
 720
 721         /* Lookup the name in the namespace */
 722
 723         status = acpi_ns_lookup(&scope_info, internal_path, ACPI_TYPE_ANY,
 724                                 ACPI_IMODE_EXECUTE,
 725                                 (flags | ACPI_NS_DONT_OPEN_SCOPE), NULL,
 726                                 return_node);
 727         if (ACPI_FAILURE(status)) {
 728                 ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "%s, %s\n",
 729                                   pathname, acpi_format_exception(status)));
 730         }
 731
 732         ACPI_FREE(internal_path);
 733         return_ACPI_STATUS(status);
 734 }
 735
 736 /*******************************************************************************
 737  *
 738  * FUNCTION:    acpi_ns_get_node
 739  *
 740  * PARAMETERS:  *pathname   - Name to be found, in external (ASL) format. The
 741  *                            \ (backslash) and ^ (carat) prefixes, and the
 742  *                            . (period) to separate segments are supported.
 743  *              prefix_node  - Root of subtree to be searched, or NS_ALL for the
 744  *                            root of the name space. If Name is fully
 745  *                            qualified (first s8 is '\'), the passed value
 746  *                            of Scope will not be accessed.
 747  *              flags       - Used to indicate whether to perform upsearch or
 748  *                            not.
 749  *              return_node - Where the Node is returned
 750  *
 751  * DESCRIPTION: Look up a name relative to a given scope and return the
 752  *              corresponding Node. NOTE: Scope can be null.
 753  *
 754  * MUTEX:       Locks namespace
 755  *
 756  ******************************************************************************/
 757
 758 acpi_status
 759 acpi_ns_get_node(struct acpi_namespace_node *prefix_node,
 760                  const char *pathname,
 761                  u32 flags, struct acpi_namespace_node **return_node)
 762 {
 763         acpi_status status;
 764
 765         ACPI_FUNCTION_TRACE_PTR(ns_get_node, ACPI_CAST_PTR(char, pathname));
 766
 767         status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
 768         if (ACPI_FAILURE(status)) {
 769                 return_ACPI_STATUS(status);
 770         }
 771
 772         status = acpi_ns_get_node_unlocked(prefix_node, pathname,
 773                                            flags, return_node);
 774
 775         (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
 776         return_ACPI_STATUS(status);
 777 }