drivers/acpi/parser/psargs.c

   1 /******************************************************************************
   2  *
   3  * Module Name: psargs - Parse AML opcode arguments
   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 <acpi/acparser.h>
  46 #include <acpi/amlcode.h>
  47 #include <acpi/acnamesp.h>
  48 #include <acpi/acdispat.h>
  49
  50 #define _COMPONENT          ACPI_PARSER
  51 ACPI_MODULE_NAME("psargs")
  52
  53 /* Local prototypes */
  54 static u32
  55 acpi_ps_get_next_package_length(struct acpi_parse_state *parser_state);
  56
  57 static union acpi_parse_object *acpi_ps_get_next_field(struct acpi_parse_state
  58                                                        *parser_state);
  59
  60 /*******************************************************************************
  61  *
  62  * FUNCTION:    acpi_ps_get_next_package_length
  63  *
  64  * PARAMETERS:  parser_state        - Current parser state object
  65  *
  66  * RETURN:      Decoded package length. On completion, the AML pointer points
  67  *              past the length byte or bytes.
  68  *
  69  * DESCRIPTION: Decode and return a package length field.
  70  *              Note: Largest package length is 28 bits, from ACPI specification
  71  *
  72  ******************************************************************************/
  73
  74 static u32
  75 acpi_ps_get_next_package_length(struct acpi_parse_state *parser_state)
  76 {
  77         u8 *aml = parser_state->aml;
  78         u32 package_length = 0;
  79         acpi_native_uint byte_count;
  80         u8 byte_zero_mask = 0x3F;       /* Default [0:5] */
  81
  82         ACPI_FUNCTION_TRACE(ps_get_next_package_length);
  83
  84         /*
  85          * Byte 0 bits [6:7] contain the number of additional bytes
  86          * used to encode the package length, either 0,1,2, or 3
  87          */
  88         byte_count = (aml[0] >> 6);
  89         parser_state->aml += (byte_count + 1);
  90
  91         /* Get bytes 3, 2, 1 as needed */
  92
  93         while (byte_count) {
  94                 /*
  95                  * Final bit positions for the package length bytes:
  96                  *      Byte3->[20:27]
  97                  *      Byte2->[12:19]
  98                  *      Byte1->[04:11]
  99                  *      Byte0->[00:03]
 100                  */
 101                 package_length |= (aml[byte_count] << ((byte_count << 3) - 4));
 102
 103                 byte_zero_mask = 0x0F;  /* Use bits [0:3] of byte 0 */
 104                 byte_count--;
 105         }
 106
 107         /* Byte 0 is a special case, either bits [0:3] or [0:5] are used */
 108
 109         package_length |= (aml[0] & byte_zero_mask);
 110         return_UINT32(package_length);
 111 }
 112
 113 /*******************************************************************************
 114  *
 115  * FUNCTION:    acpi_ps_get_next_package_end
 116  *
 117  * PARAMETERS:  parser_state        - Current parser state object
 118  *
 119  * RETURN:      Pointer to end-of-package +1
 120  *
 121  * DESCRIPTION: Get next package length and return a pointer past the end of
 122  *              the package.  Consumes the package length field
 123  *
 124  ******************************************************************************/
 125
 126 u8 *acpi_ps_get_next_package_end(struct acpi_parse_state *parser_state)
 127 {
 128         u8 *start = parser_state->aml;
 129         u32 package_length;
 130
 131         ACPI_FUNCTION_TRACE(ps_get_next_package_end);
 132
 133         /* Function below updates parser_state->Aml */
 134
 135         package_length = acpi_ps_get_next_package_length(parser_state);
 136
 137         return_PTR(start + package_length);     /* end of package */
 138 }
 139
 140 /*******************************************************************************
 141  *
 142  * FUNCTION:    acpi_ps_get_next_namestring
 143  *
 144  * PARAMETERS:  parser_state        - Current parser state object
 145  *
 146  * RETURN:      Pointer to the start of the name string (pointer points into
 147  *              the AML.
 148  *
 149  * DESCRIPTION: Get next raw namestring within the AML stream.  Handles all name
 150  *              prefix characters.  Set parser state to point past the string.
 151  *              (Name is consumed from the AML.)
 152  *
 153  ******************************************************************************/
 154
 155 char *acpi_ps_get_next_namestring(struct acpi_parse_state *parser_state)
 156 {
 157         u8 *start = parser_state->aml;
 158         u8 *end = parser_state->aml;
 159
 160         ACPI_FUNCTION_TRACE(ps_get_next_namestring);
 161
 162         /* Point past any namestring prefix characters (backslash or carat) */
 163
 164         while (acpi_ps_is_prefix_char(*end)) {
 165                 end++;
 166         }
 167
 168         /* Decode the path prefix character */
 169
 170         switch (*end) {
 171         case 0:
 172
 173                 /* null_name */
 174
 175                 if (end == start) {
 176                         start = NULL;
 177                 }
 178                 end++;
 179                 break;
 180
 181         case AML_DUAL_NAME_PREFIX:
 182
 183                 /* Two name segments */
 184
 185                 end += 1 + (2 * ACPI_NAME_SIZE);
 186                 break;
 187
 188         case AML_MULTI_NAME_PREFIX_OP:
 189
 190                 /* Multiple name segments, 4 chars each, count in next byte */
 191
 192                 end += 2 + (*(end + 1) * ACPI_NAME_SIZE);
 193                 break;
 194
 195         default:
 196
 197                 /* Single name segment */
 198
 199                 end += ACPI_NAME_SIZE;
 200                 break;
 201         }
 202
 203         parser_state->aml = end;
 204         return_PTR((char *)start);
 205 }
 206
 207 /*******************************************************************************
 208  *
 209  * FUNCTION:    acpi_ps_get_next_namepath
 210  *
 211  * PARAMETERS:  parser_state        - Current parser state object
 212  *              Arg                 - Where the namepath will be stored
 213  *              arg_count           - If the namepath points to a control method
 214  *                                    the method's argument is returned here.
 215  *              possible_method_call - Whether the namepath can possibly be the
 216  *                                    start of a method call
 217  *
 218  * RETURN:      Status
 219  *
 220  * DESCRIPTION: Get next name (if method call, return # of required args).
 221  *              Names are looked up in the internal namespace to determine
 222  *              if the name represents a control method.  If a method
 223  *              is found, the number of arguments to the method is returned.
 224  *              This information is critical for parsing to continue correctly.
 225  *
 226  ******************************************************************************/
 227
 228 acpi_status
 229 acpi_ps_get_next_namepath(struct acpi_walk_state *walk_state,
 230                           struct acpi_parse_state *parser_state,
 231                           union acpi_parse_object *arg, u8 possible_method_call)
 232 {
 233         acpi_status status;
 234         char *path;
 235         union acpi_parse_object *name_op;
 236         union acpi_operand_object *method_desc;
 237         struct acpi_namespace_node *node;
 238         u8 *start = parser_state->aml;
 239
 240         ACPI_FUNCTION_TRACE(ps_get_next_namepath);
 241
 242         path = acpi_ps_get_next_namestring(parser_state);
 243         acpi_ps_init_op(arg, AML_INT_NAMEPATH_OP);
 244
 245         /* Null path case is allowed, just exit */
 246
 247         if (!path) {
 248                 arg->common.value.name = path;
 249                 return_ACPI_STATUS(AE_OK);
 250         }
 251
 252         /*
 253          * Lookup the name in the internal namespace, starting with the current
 254          * scope. We don't want to add anything new to the namespace here,
 255          * however, so we use MODE_EXECUTE.
 256          * Allow searching of the parent tree, but don't open a new scope -
 257          * we just want to lookup the object (must be mode EXECUTE to perform
 258          * the upsearch)
 259          */
 260         status = acpi_ns_lookup(walk_state->scope_info, path,
 261                                 ACPI_TYPE_ANY, ACPI_IMODE_EXECUTE,
 262                                 ACPI_NS_SEARCH_PARENT | ACPI_NS_DONT_OPEN_SCOPE,
 263                                 NULL, &node);
 264
 265         /*
 266          * If this name is a control method invocation, we must
 267          * setup the method call
 268          */
 269         if (ACPI_SUCCESS(status) &&
 270             possible_method_call && (node->type == ACPI_TYPE_METHOD)) {
 271                 if (walk_state->opcode == AML_UNLOAD_OP) {
 272                         /*
 273                          * acpi_ps_get_next_namestring has increased the AML pointer,
 274                          * so we need to restore the saved AML pointer for method call.
 275                          */
 276                         walk_state->parser_state.aml = start;
 277                         walk_state->arg_count = 1;
 278                         acpi_ps_init_op(arg, AML_INT_METHODCALL_OP);
 279                         return_ACPI_STATUS(AE_OK);
 280                 }
 281
 282                 /* This name is actually a control method invocation */
 283
 284                 method_desc = acpi_ns_get_attached_object(node);
 285                 ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
 286                                   "Control Method - %p Desc %p Path=%p\n", node,
 287                                   method_desc, path));
 288
 289                 name_op = acpi_ps_alloc_op(AML_INT_NAMEPATH_OP);
 290                 if (!name_op) {
 291                         return_ACPI_STATUS(AE_NO_MEMORY);
 292                 }
 293
 294                 /* Change Arg into a METHOD CALL and attach name to it */
 295
 296                 acpi_ps_init_op(arg, AML_INT_METHODCALL_OP);
 297                 name_op->common.value.name = path;
 298
 299                 /* Point METHODCALL/NAME to the METHOD Node */
 300
 301                 name_op->common.node = node;
 302                 acpi_ps_append_arg(arg, name_op);
 303
 304                 if (!method_desc) {
 305                         ACPI_ERROR((AE_INFO,
 306                                     "Control Method %p has no attached object",
 307                                     node));
 308                         return_ACPI_STATUS(AE_AML_INTERNAL);
 309                 }
 310
 311                 ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
 312                                   "Control Method - %p Args %X\n",
 313                                   node, method_desc->method.param_count));
 314
 315                 /* Get the number of arguments to expect */
 316
 317                 walk_state->arg_count = method_desc->method.param_count;
 318                 return_ACPI_STATUS(AE_OK);
 319         }
 320
 321         /*
 322          * Special handling if the name was not found during the lookup -
 323          * some not_found cases are allowed
 324          */
 325         if (status == AE_NOT_FOUND) {
 326
 327                 /* 1) not_found is ok during load pass 1/2 (allow forward references) */
 328
 329                 if ((walk_state->parse_flags & ACPI_PARSE_MODE_MASK) !=
 330                     ACPI_PARSE_EXECUTE) {
 331                         status = AE_OK;
 332                 }
 333
 334                 /* 2) not_found during a cond_ref_of(x) is ok by definition */
 335
 336                 else if (walk_state->op->common.aml_opcode ==
 337                          AML_COND_REF_OF_OP) {
 338                         status = AE_OK;
 339                 }
 340
 341                 /*
 342                  * 3) not_found while building a Package is ok at this point, we
 343                  * may flag as an error later if slack mode is not enabled.
 344                  * (Some ASL code depends on allowing this behavior)
 345                  */
 346                 else if ((arg->common.parent) &&
 347                          ((arg->common.parent->common.aml_opcode ==
 348                            AML_PACKAGE_OP)
 349                           || (arg->common.parent->common.aml_opcode ==
 350                               AML_VAR_PACKAGE_OP))) {
 351                         status = AE_OK;
 352                 }
 353         }
 354
 355         /* Final exception check (may have been changed from code above) */
 356
 357         if (ACPI_FAILURE(status)) {
 358                 ACPI_ERROR_NAMESPACE(path, status);
 359
 360                 if ((walk_state->parse_flags & ACPI_PARSE_MODE_MASK) ==
 361                     ACPI_PARSE_EXECUTE) {
 362
 363                         /* Report a control method execution error */
 364
 365                         status = acpi_ds_method_error(status, walk_state);
 366                 }
 367         }
 368
 369         /* Save the namepath */
 370
 371         arg->common.value.name = path;
 372         return_ACPI_STATUS(status);
 373 }
 374
 375 /*******************************************************************************
 376  *
 377  * FUNCTION:    acpi_ps_get_next_simple_arg
 378  *
 379  * PARAMETERS:  parser_state        - Current parser state object
 380  *              arg_type            - The argument type (AML_*_ARG)
 381  *              Arg                 - Where the argument is returned
 382  *
 383  * RETURN:      None
 384  *
 385  * DESCRIPTION: Get the next simple argument (constant, string, or namestring)
 386  *
 387  ******************************************************************************/
 388
 389 void
 390 acpi_ps_get_next_simple_arg(struct acpi_parse_state *parser_state,
 391                             u32 arg_type, union acpi_parse_object *arg)
 392 {
 393         u32 length;
 394         u16 opcode;
 395         u8 *aml = parser_state->aml;
 396
 397         ACPI_FUNCTION_TRACE_U32(ps_get_next_simple_arg, arg_type);
 398
 399         switch (arg_type) {
 400         case ARGP_BYTEDATA:
 401
 402                 /* Get 1 byte from the AML stream */
 403
 404                 opcode = AML_BYTE_OP;
 405                 arg->common.value.integer = (acpi_integer) * aml;
 406                 length = 1;
 407                 break;
 408
 409         case ARGP_WORDDATA:
 410
 411                 /* Get 2 bytes from the AML stream */
 412
 413                 opcode = AML_WORD_OP;
 414                 ACPI_MOVE_16_TO_64(&arg->common.value.integer, aml);
 415                 length = 2;
 416                 break;
 417
 418         case ARGP_DWORDDATA:
 419
 420                 /* Get 4 bytes from the AML stream */
 421
 422                 opcode = AML_DWORD_OP;
 423                 ACPI_MOVE_32_TO_64(&arg->common.value.integer, aml);
 424                 length = 4;
 425                 break;
 426
 427         case ARGP_QWORDDATA:
 428
 429                 /* Get 8 bytes from the AML stream */
 430
 431                 opcode = AML_QWORD_OP;
 432                 ACPI_MOVE_64_TO_64(&arg->common.value.integer, aml);
 433                 length = 8;
 434                 break;
 435
 436         case ARGP_CHARLIST:
 437
 438                 /* Get a pointer to the string, point past the string */
 439
 440                 opcode = AML_STRING_OP;
 441                 arg->common.value.string = ACPI_CAST_PTR(char, aml);
 442
 443                 /* Find the null terminator */
 444
 445                 length = 0;
 446                 while (aml[length]) {
 447                         length++;
 448                 }
 449                 length++;
 450                 break;
 451
 452         case ARGP_NAME:
 453         case ARGP_NAMESTRING:
 454
 455                 acpi_ps_init_op(arg, AML_INT_NAMEPATH_OP);
 456                 arg->common.value.name =
 457                     acpi_ps_get_next_namestring(parser_state);
 458                 return_VOID;
 459
 460         default:
 461
 462                 ACPI_ERROR((AE_INFO, "Invalid ArgType %X", arg_type));
 463                 return_VOID;
 464         }
 465
 466         acpi_ps_init_op(arg, opcode);
 467         parser_state->aml += length;
 468         return_VOID;
 469 }
 470
 471 /*******************************************************************************
 472  *
 473  * FUNCTION:    acpi_ps_get_next_field
 474  *
 475  * PARAMETERS:  parser_state        - Current parser state object
 476  *
 477  * RETURN:      A newly allocated FIELD op
 478  *
 479  * DESCRIPTION: Get next field (named_field, reserved_field, or access_field)
 480  *
 481  ******************************************************************************/
 482
 483 static union acpi_parse_object *acpi_ps_get_next_field(struct acpi_parse_state
 484                                                        *parser_state)
 485 {
 486         u32 aml_offset = (u32)
 487             ACPI_PTR_DIFF(parser_state->aml,
 488                           parser_state->aml_start);
 489         union acpi_parse_object *field;
 490         u16 opcode;
 491         u32 name;
 492
 493         ACPI_FUNCTION_TRACE(ps_get_next_field);
 494
 495         /* Determine field type */
 496
 497         switch (ACPI_GET8(parser_state->aml)) {
 498         default:
 499
 500                 opcode = AML_INT_NAMEDFIELD_OP;
 501                 break;
 502
 503         case 0x00:
 504
 505                 opcode = AML_INT_RESERVEDFIELD_OP;
 506                 parser_state->aml++;
 507                 break;
 508
 509         case 0x01:
 510
 511                 opcode = AML_INT_ACCESSFIELD_OP;
 512                 parser_state->aml++;
 513                 break;
 514         }
 515
 516         /* Allocate a new field op */
 517
 518         field = acpi_ps_alloc_op(opcode);
 519         if (!field) {
 520                 return_PTR(NULL);
 521         }
 522
 523         field->common.aml_offset = aml_offset;
 524
 525         /* Decode the field type */
 526
 527         switch (opcode) {
 528         case AML_INT_NAMEDFIELD_OP:
 529
 530                 /* Get the 4-character name */
 531
 532                 ACPI_MOVE_32_TO_32(&name, parser_state->aml);
 533                 acpi_ps_set_name(field, name);
 534                 parser_state->aml += ACPI_NAME_SIZE;
 535
 536                 /* Get the length which is encoded as a package length */
 537
 538                 field->common.value.size =
 539                     acpi_ps_get_next_package_length(parser_state);
 540                 break;
 541
 542         case AML_INT_RESERVEDFIELD_OP:
 543
 544                 /* Get the length which is encoded as a package length */
 545
 546                 field->common.value.size =
 547                     acpi_ps_get_next_package_length(parser_state);
 548                 break;
 549
 550         case AML_INT_ACCESSFIELD_OP:
 551
 552                 /*
 553                  * Get access_type and access_attrib and merge into the field Op
 554                  * access_type is first operand, access_attribute is second
 555                  */
 556                 field->common.value.integer =
 557                     (((u32) ACPI_GET8(parser_state->aml) << 8));
 558                 parser_state->aml++;
 559                 field->common.value.integer |= ACPI_GET8(parser_state->aml);
 560                 parser_state->aml++;
 561                 break;
 562
 563         default:
 564
 565                 /* Opcode was set in previous switch */
 566                 break;
 567         }
 568
 569         return_PTR(field);
 570 }
 571
 572 /*******************************************************************************
 573  *
 574  * FUNCTION:    acpi_ps_get_next_arg
 575  *
 576  * PARAMETERS:  walk_state          - Current state
 577  *              parser_state        - Current parser state object
 578  *              arg_type            - The argument type (AML_*_ARG)
 579  *              return_arg          - Where the next arg is returned
 580  *
 581  * RETURN:      Status, and an op object containing the next argument.
 582  *
 583  * DESCRIPTION: Get next argument (including complex list arguments that require
 584  *              pushing the parser stack)
 585  *
 586  ******************************************************************************/
 587
 588 acpi_status
 589 acpi_ps_get_next_arg(struct acpi_walk_state *walk_state,
 590                      struct acpi_parse_state *parser_state,
 591                      u32 arg_type, union acpi_parse_object **return_arg)
 592 {
 593         union acpi_parse_object *arg = NULL;
 594         union acpi_parse_object *prev = NULL;
 595         union acpi_parse_object *field;
 596         u32 subop;
 597         acpi_status status = AE_OK;
 598
 599         ACPI_FUNCTION_TRACE_PTR(ps_get_next_arg, parser_state);
 600
 601         switch (arg_type) {
 602         case ARGP_BYTEDATA:
 603         case ARGP_WORDDATA:
 604         case ARGP_DWORDDATA:
 605         case ARGP_CHARLIST:
 606         case ARGP_NAME:
 607         case ARGP_NAMESTRING:
 608
 609                 /* Constants, strings, and namestrings are all the same size */
 610
 611                 arg = acpi_ps_alloc_op(AML_BYTE_OP);
 612                 if (!arg) {
 613                         return_ACPI_STATUS(AE_NO_MEMORY);
 614                 }
 615                 acpi_ps_get_next_simple_arg(parser_state, arg_type, arg);
 616                 break;
 617
 618         case ARGP_PKGLENGTH:
 619
 620                 /* Package length, nothing returned */
 621
 622                 parser_state->pkg_end =
 623                     acpi_ps_get_next_package_end(parser_state);
 624                 break;
 625
 626         case ARGP_FIELDLIST:
 627
 628                 if (parser_state->aml < parser_state->pkg_end) {
 629
 630                         /* Non-empty list */
 631
 632                         while (parser_state->aml < parser_state->pkg_end) {
 633                                 field = acpi_ps_get_next_field(parser_state);
 634                                 if (!field) {
 635                                         return_ACPI_STATUS(AE_NO_MEMORY);
 636                                 }
 637
 638                                 if (prev) {
 639                                         prev->common.next = field;
 640                                 } else {
 641                                         arg = field;
 642                                 }
 643                                 prev = field;
 644                         }
 645
 646                         /* Skip to End of byte data */
 647
 648                         parser_state->aml = parser_state->pkg_end;
 649                 }
 650                 break;
 651
 652         case ARGP_BYTELIST:
 653
 654                 if (parser_state->aml < parser_state->pkg_end) {
 655
 656                         /* Non-empty list */
 657
 658                         arg = acpi_ps_alloc_op(AML_INT_BYTELIST_OP);
 659                         if (!arg) {
 660                                 return_ACPI_STATUS(AE_NO_MEMORY);
 661                         }
 662
 663                         /* Fill in bytelist data */
 664
 665                         arg->common.value.size = (u32)
 666                             ACPI_PTR_DIFF(parser_state->pkg_end,
 667                                           parser_state->aml);
 668                         arg->named.data = parser_state->aml;
 669
 670                         /* Skip to End of byte data */
 671
 672                         parser_state->aml = parser_state->pkg_end;
 673                 }
 674                 break;
 675
 676         case ARGP_TARGET:
 677         case ARGP_SUPERNAME:
 678         case ARGP_SIMPLENAME:
 679
 680                 subop = acpi_ps_peek_opcode(parser_state);
 681                 if (subop == 0 ||
 682                     acpi_ps_is_leading_char(subop) ||
 683                     acpi_ps_is_prefix_char(subop)) {
 684
 685                         /* null_name or name_string */
 686
 687                         arg = acpi_ps_alloc_op(AML_INT_NAMEPATH_OP);
 688                         if (!arg) {
 689                                 return_ACPI_STATUS(AE_NO_MEMORY);
 690                         }
 691
 692                         /* To support super_name arg of Unload */
 693
 694                         if (walk_state->opcode == AML_UNLOAD_OP) {
 695                                 status =
 696                                     acpi_ps_get_next_namepath(walk_state,
 697                                                               parser_state, arg,
 698                                                               1);
 699
 700                                 /*
 701                                  * If the super_name arg of Unload is a method call,
 702                                  * we have restored the AML pointer, just free this Arg
 703                                  */
 704                                 if (arg->common.aml_opcode ==
 705                                     AML_INT_METHODCALL_OP) {
 706                                         acpi_ps_free_op(arg);
 707                                         arg = NULL;
 708                                 }
 709                         } else {
 710                                 status =
 711                                     acpi_ps_get_next_namepath(walk_state,
 712                                                               parser_state, arg,
 713                                                               0);
 714                         }
 715                 } else {
 716                         /* Single complex argument, nothing returned */
 717
 718                         walk_state->arg_count = 1;
 719                 }
 720                 break;
 721
 722         case ARGP_DATAOBJ:
 723         case ARGP_TERMARG:
 724
 725                 /* Single complex argument, nothing returned */
 726
 727                 walk_state->arg_count = 1;
 728                 break;
 729
 730         case ARGP_DATAOBJLIST:
 731         case ARGP_TERMLIST:
 732         case ARGP_OBJLIST:
 733
 734                 if (parser_state->aml < parser_state->pkg_end) {
 735
 736                         /* Non-empty list of variable arguments, nothing returned */
 737
 738                         walk_state->arg_count = ACPI_VAR_ARGS;
 739                 }
 740                 break;
 741
 742         default:
 743
 744                 ACPI_ERROR((AE_INFO, "Invalid ArgType: %X", arg_type));
 745                 status = AE_AML_OPERAND_TYPE;
 746                 break;
 747         }
 748
 749         *return_arg = arg;
 750         return_ACPI_STATUS(status);
 751 }