drivers/acpi/resources/rsutils.c

   1 /*******************************************************************************
   2  *
   3  * Module Name: rsutils - Utilities for the resource manager
   4  *
   5  ******************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2006, R. Byron Moore
   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/acnamesp.h>
  46 #include <acpi/acresrc.h>
  47
  48 #define _COMPONENT          ACPI_RESOURCES
  49 ACPI_MODULE_NAME("rsutils")
  50
  51 /*******************************************************************************
  52  *
  53  * FUNCTION:    acpi_rs_decode_bitmask
  54  *
  55  * PARAMETERS:  Mask            - Bitmask to decode
  56  *              List            - Where the converted list is returned
  57  *
  58  * RETURN:      Count of bits set (length of list)
  59  *
  60  * DESCRIPTION: Convert a bit mask into a list of values
  61  *
  62  ******************************************************************************/
  63 u8 acpi_rs_decode_bitmask(u16 mask, u8 * list)
  64 {
  65         acpi_native_uint i;
  66         u8 bit_count;
  67
  68         ACPI_FUNCTION_ENTRY();
  69
  70         /* Decode the mask bits */
  71
  72         for (i = 0, bit_count = 0; mask; i++) {
  73                 if (mask & 0x0001) {
  74                         list[bit_count] = (u8) i;
  75                         bit_count++;
  76                 }
  77
  78                 mask >>= 1;
  79         }
  80
  81         return (bit_count);
  82 }
  83
  84 /*******************************************************************************
  85  *
  86  * FUNCTION:    acpi_rs_encode_bitmask
  87  *
  88  * PARAMETERS:  List            - List of values to encode
  89  *              Count           - Length of list
  90  *
  91  * RETURN:      Encoded bitmask
  92  *
  93  * DESCRIPTION: Convert a list of values to an encoded bitmask
  94  *
  95  ******************************************************************************/
  96
  97 u16 acpi_rs_encode_bitmask(u8 * list, u8 count)
  98 {
  99         acpi_native_uint i;
 100         u16 mask;
 101
 102         ACPI_FUNCTION_ENTRY();
 103
 104         /* Encode the list into a single bitmask */
 105
 106         for (i = 0, mask = 0; i < count; i++) {
 107                 mask |= (0x0001 << list[i]);
 108         }
 109
 110         return (mask);
 111 }
 112
 113 /*******************************************************************************
 114  *
 115  * FUNCTION:    acpi_rs_move_data
 116  *
 117  * PARAMETERS:  Destination         - Pointer to the destination descriptor
 118  *              Source              - Pointer to the source descriptor
 119  *              item_count          - How many items to move
 120  *              move_type           - Byte width
 121  *
 122  * RETURN:      None
 123  *
 124  * DESCRIPTION: Move multiple data items from one descriptor to another. Handles
 125  *              alignment issues and endian issues if necessary, as configured
 126  *              via the ACPI_MOVE_* macros. (This is why a memcpy is not used)
 127  *
 128  ******************************************************************************/
 129
 130 void
 131 acpi_rs_move_data(void *destination, void *source, u16 item_count, u8 move_type)
 132 {
 133         acpi_native_uint i;
 134
 135         ACPI_FUNCTION_ENTRY();
 136
 137         /* One move per item */
 138
 139         for (i = 0; i < item_count; i++) {
 140                 switch (move_type) {
 141                         /*
 142                          * For the 8-bit case, we can perform the move all at once
 143                          * since there are no alignment or endian issues
 144                          */
 145                 case ACPI_RSC_MOVE8:
 146                         ACPI_MEMCPY(destination, source, item_count);
 147                         return;
 148
 149                         /*
 150                          * 16-, 32-, and 64-bit cases must use the move macros that perform
 151                          * endian conversion and/or accomodate hardware that cannot perform
 152                          * misaligned memory transfers
 153                          */
 154                 case ACPI_RSC_MOVE16:
 155                         ACPI_MOVE_16_TO_16(&ACPI_CAST_PTR(u16, destination)[i],
 156                                            &ACPI_CAST_PTR(u16, source)[i]);
 157                         break;
 158
 159                 case ACPI_RSC_MOVE32:
 160                         ACPI_MOVE_32_TO_32(&ACPI_CAST_PTR(u32, destination)[i],
 161                                            &ACPI_CAST_PTR(u32, source)[i]);
 162                         break;
 163
 164                 case ACPI_RSC_MOVE64:
 165                         ACPI_MOVE_64_TO_64(&ACPI_CAST_PTR(u64, destination)[i],
 166                                            &ACPI_CAST_PTR(u64, source)[i]);
 167                         break;
 168
 169                 default:
 170                         return;
 171                 }
 172         }
 173 }
 174
 175 /*******************************************************************************
 176  *
 177  * FUNCTION:    acpi_rs_set_resource_length
 178  *
 179  * PARAMETERS:  total_length        - Length of the AML descriptor, including
 180  *                                    the header and length fields.
 181  *              Aml                 - Pointer to the raw AML descriptor
 182  *
 183  * RETURN:      None
 184  *
 185  * DESCRIPTION: Set the resource_length field of an AML
 186  *              resource descriptor, both Large and Small descriptors are
 187  *              supported automatically. Note: Descriptor Type field must
 188  *              be valid.
 189  *
 190  ******************************************************************************/
 191
 192 void
 193 acpi_rs_set_resource_length(acpi_rsdesc_size total_length,
 194                             union aml_resource *aml)
 195 {
 196         acpi_rs_length resource_length;
 197
 198         ACPI_FUNCTION_ENTRY();
 199
 200         /* Length is the total descriptor length minus the header length */
 201
 202         resource_length = (acpi_rs_length)
 203             (total_length - acpi_ut_get_resource_header_length(aml));
 204
 205         /* Length is stored differently for large and small descriptors */
 206
 207         if (aml->small_header.descriptor_type & ACPI_RESOURCE_NAME_LARGE) {
 208                 /* Large descriptor -- bytes 1-2 contain the 16-bit length */
 209
 210                 ACPI_MOVE_16_TO_16(&aml->large_header.resource_length,
 211                                    &resource_length);
 212         } else {
 213                 /* Small descriptor -- bits 2:0 of byte 0 contain the length */
 214
 215                 aml->small_header.descriptor_type = (u8)
 216
 217                     /* Clear any existing length, preserving descriptor type bits */
 218                     ((aml->small_header.
 219                       descriptor_type & ~ACPI_RESOURCE_NAME_SMALL_LENGTH_MASK)
 220
 221                      | resource_length);
 222         }
 223 }
 224
 225 /*******************************************************************************
 226  *
 227  * FUNCTION:    acpi_rs_set_resource_header
 228  *
 229  * PARAMETERS:  descriptor_type     - Byte to be inserted as the type
 230  *              total_length        - Length of the AML descriptor, including
 231  *                                    the header and length fields.
 232  *              Aml                 - Pointer to the raw AML descriptor
 233  *
 234  * RETURN:      None
 235  *
 236  * DESCRIPTION: Set the descriptor_type and resource_length fields of an AML
 237  *              resource descriptor, both Large and Small descriptors are
 238  *              supported automatically
 239  *
 240  ******************************************************************************/
 241
 242 void
 243 acpi_rs_set_resource_header(u8 descriptor_type,
 244                             acpi_rsdesc_size total_length,
 245                             union aml_resource *aml)
 246 {
 247         ACPI_FUNCTION_ENTRY();
 248
 249         /* Set the Resource Type */
 250
 251         aml->small_header.descriptor_type = descriptor_type;
 252
 253         /* Set the Resource Length */
 254
 255         acpi_rs_set_resource_length(total_length, aml);
 256 }
 257
 258 /*******************************************************************************
 259  *
 260  * FUNCTION:    acpi_rs_strcpy
 261  *
 262  * PARAMETERS:  Destination         - Pointer to the destination string
 263  *              Source              - Pointer to the source string
 264  *
 265  * RETURN:      String length, including NULL terminator
 266  *
 267  * DESCRIPTION: Local string copy that returns the string length, saving a
 268  *              strcpy followed by a strlen.
 269  *
 270  ******************************************************************************/
 271
 272 static u16 acpi_rs_strcpy(char *destination, char *source)
 273 {
 274         u16 i;
 275
 276         ACPI_FUNCTION_ENTRY();
 277
 278         for (i = 0; source[i]; i++) {
 279                 destination[i] = source[i];
 280         }
 281
 282         destination[i] = 0;
 283
 284         /* Return string length including the NULL terminator */
 285
 286         return ((u16) (i + 1));
 287 }
 288
 289 /*******************************************************************************
 290  *
 291  * FUNCTION:    acpi_rs_get_resource_source
 292  *
 293  * PARAMETERS:  resource_length     - Length field of the descriptor
 294  *              minimum_length      - Minimum length of the descriptor (minus
 295  *                                    any optional fields)
 296  *              resource_source     - Where the resource_source is returned
 297  *              Aml                 - Pointer to the raw AML descriptor
 298  *              string_ptr          - (optional) where to store the actual
 299  *                                    resource_source string
 300  *
 301  * RETURN:      Length of the string plus NULL terminator, rounded up to 32 bit
 302  *
 303  * DESCRIPTION: Copy the optional resource_source data from a raw AML descriptor
 304  *              to an internal resource descriptor
 305  *
 306  ******************************************************************************/
 307
 308 acpi_rs_length
 309 acpi_rs_get_resource_source(acpi_rs_length resource_length,
 310                             acpi_rs_length minimum_length,
 311                             struct acpi_resource_source * resource_source,
 312                             union aml_resource * aml, char *string_ptr)
 313 {
 314         acpi_rsdesc_size total_length;
 315         u8 *aml_resource_source;
 316
 317         ACPI_FUNCTION_ENTRY();
 318
 319         total_length =
 320             resource_length + sizeof(struct aml_resource_large_header);
 321         aml_resource_source = ACPI_ADD_PTR(u8, aml, minimum_length);
 322
 323         /*
 324          * resource_source is present if the length of the descriptor is longer than
 325          * the minimum length.
 326          *
 327          * Note: Some resource descriptors will have an additional null, so
 328          * we add 1 to the minimum length.
 329          */
 330         if (total_length > (acpi_rsdesc_size) (minimum_length + 1)) {
 331                 /* Get the resource_source_index */
 332
 333                 resource_source->index = aml_resource_source[0];
 334
 335                 resource_source->string_ptr = string_ptr;
 336                 if (!string_ptr) {
 337                         /*
 338                          * String destination pointer is not specified; Set the String
 339                          * pointer to the end of the current resource_source structure.
 340                          */
 341                         resource_source->string_ptr =
 342                             ACPI_ADD_PTR(char, resource_source,
 343                                          sizeof(struct acpi_resource_source));
 344                 }
 345
 346                 /*
 347                  * In order for the struct_size to fall on a 32-bit boundary, calculate
 348                  * the length of the string (+1 for the NULL terminator) and expand the
 349                  * struct_size to the next 32-bit boundary.
 350                  *
 351                  * Zero the entire area of the buffer.
 352                  */
 353                 total_length =
 354                     ACPI_ROUND_UP_to_32_bITS(ACPI_STRLEN
 355                                              ((char *)&aml_resource_source[1]) +
 356                                              1);
 357                 ACPI_MEMSET(resource_source->string_ptr, 0, total_length);
 358
 359                 /* Copy the resource_source string to the destination */
 360
 361                 resource_source->string_length =
 362                     acpi_rs_strcpy(resource_source->string_ptr,
 363                                    (char *)&aml_resource_source[1]);
 364
 365                 return ((acpi_rs_length) total_length);
 366         }
 367
 368         /* resource_source is not present */
 369
 370         resource_source->index = 0;
 371         resource_source->string_length = 0;
 372         resource_source->string_ptr = NULL;
 373         return (0);
 374 }
 375
 376 /*******************************************************************************
 377  *
 378  * FUNCTION:    acpi_rs_set_resource_source
 379  *
 380  * PARAMETERS:  Aml                 - Pointer to the raw AML descriptor
 381  *              minimum_length      - Minimum length of the descriptor (minus
 382  *                                    any optional fields)
 383  *              resource_source     - Internal resource_source
 384
 385  *
 386  * RETURN:      Total length of the AML descriptor
 387  *
 388  * DESCRIPTION: Convert an optional resource_source from internal format to a
 389  *              raw AML resource descriptor
 390  *
 391  ******************************************************************************/
 392
 393 acpi_rsdesc_size
 394 acpi_rs_set_resource_source(union aml_resource * aml,
 395                             acpi_rs_length minimum_length,
 396                             struct acpi_resource_source * resource_source)
 397 {
 398         u8 *aml_resource_source;
 399         acpi_rsdesc_size descriptor_length;
 400
 401         ACPI_FUNCTION_ENTRY();
 402
 403         descriptor_length = minimum_length;
 404
 405         /* Non-zero string length indicates presence of a resource_source */
 406
 407         if (resource_source->string_length) {
 408                 /* Point to the end of the AML descriptor */
 409
 410                 aml_resource_source = ACPI_ADD_PTR(u8, aml, minimum_length);
 411
 412                 /* Copy the resource_source_index */
 413
 414                 aml_resource_source[0] = (u8) resource_source->index;
 415
 416                 /* Copy the resource_source string */
 417
 418                 ACPI_STRCPY((char *)&aml_resource_source[1],
 419                             resource_source->string_ptr);
 420
 421                 /*
 422                  * Add the length of the string (+ 1 for null terminator) to the
 423                  * final descriptor length
 424                  */
 425                 descriptor_length +=
 426                     ((acpi_rsdesc_size) resource_source->string_length + 1);
 427         }
 428
 429         /* Return the new total length of the AML descriptor */
 430
 431         return (descriptor_length);
 432 }
 433
 434 /*******************************************************************************
 435  *
 436  * FUNCTION:    acpi_rs_get_prt_method_data
 437  *
 438  * PARAMETERS:  Handle          - a handle to the containing object
 439  *              ret_buffer      - a pointer to a buffer structure for the
 440  *                                  results
 441  *
 442  * RETURN:      Status
 443  *
 444  * DESCRIPTION: This function is called to get the _PRT value of an object
 445  *              contained in an object specified by the handle passed in
 446  *
 447  *              If the function fails an appropriate status will be returned
 448  *              and the contents of the callers buffer is undefined.
 449  *
 450  ******************************************************************************/
 451
 452 acpi_status
 453 acpi_rs_get_prt_method_data(acpi_handle handle, struct acpi_buffer * ret_buffer)
 454 {
 455         union acpi_operand_object *obj_desc;
 456         acpi_status status;
 457
 458         ACPI_FUNCTION_TRACE("rs_get_prt_method_data");
 459
 460         /* Parameters guaranteed valid by caller */
 461
 462         /* Execute the method, no parameters */
 463
 464         status = acpi_ut_evaluate_object(handle, METHOD_NAME__PRT,
 465                                          ACPI_BTYPE_PACKAGE, &obj_desc);
 466         if (ACPI_FAILURE(status)) {
 467                 return_ACPI_STATUS(status);
 468         }
 469
 470         /*
 471          * Create a resource linked list from the byte stream buffer that comes
 472          * back from the _CRS method execution.
 473          */
 474         status = acpi_rs_create_pci_routing_table(obj_desc, ret_buffer);
 475
 476         /* On exit, we must delete the object returned by evaluate_object */
 477
 478         acpi_ut_remove_reference(obj_desc);
 479         return_ACPI_STATUS(status);
 480 }
 481
 482 /*******************************************************************************
 483  *
 484  * FUNCTION:    acpi_rs_get_crs_method_data
 485  *
 486  * PARAMETERS:  Handle          - a handle to the containing object
 487  *              ret_buffer      - a pointer to a buffer structure for the
 488  *                                  results
 489  *
 490  * RETURN:      Status
 491  *
 492  * DESCRIPTION: This function is called to get the _CRS value of an object
 493  *              contained in an object specified by the handle passed in
 494  *
 495  *              If the function fails an appropriate status will be returned
 496  *              and the contents of the callers buffer is undefined.
 497  *
 498  ******************************************************************************/
 499
 500 acpi_status
 501 acpi_rs_get_crs_method_data(acpi_handle handle, struct acpi_buffer *ret_buffer)
 502 {
 503         union acpi_operand_object *obj_desc;
 504         acpi_status status;
 505
 506         ACPI_FUNCTION_TRACE("rs_get_crs_method_data");
 507
 508         /* Parameters guaranteed valid by caller */
 509
 510         /* Execute the method, no parameters */
 511
 512         status = acpi_ut_evaluate_object(handle, METHOD_NAME__CRS,
 513                                          ACPI_BTYPE_BUFFER, &obj_desc);
 514         if (ACPI_FAILURE(status)) {
 515                 return_ACPI_STATUS(status);
 516         }
 517
 518         /*
 519          * Make the call to create a resource linked list from the
 520          * byte stream buffer that comes back from the _CRS method
 521          * execution.
 522          */
 523         status = acpi_rs_create_resource_list(obj_desc, ret_buffer);
 524
 525         /* on exit, we must delete the object returned by evaluate_object */
 526
 527         acpi_ut_remove_reference(obj_desc);
 528         return_ACPI_STATUS(status);
 529 }
 530
 531 /*******************************************************************************
 532  *
 533  * FUNCTION:    acpi_rs_get_prs_method_data
 534  *
 535  * PARAMETERS:  Handle          - a handle to the containing object
 536  *              ret_buffer      - a pointer to a buffer structure for the
 537  *                                  results
 538  *
 539  * RETURN:      Status
 540  *
 541  * DESCRIPTION: This function is called to get the _PRS value of an object
 542  *              contained in an object specified by the handle passed in
 543  *
 544  *              If the function fails an appropriate status will be returned
 545  *              and the contents of the callers buffer is undefined.
 546  *
 547  ******************************************************************************/
 548
 549 #ifdef ACPI_FUTURE_USAGE
 550 acpi_status
 551 acpi_rs_get_prs_method_data(acpi_handle handle, struct acpi_buffer *ret_buffer)
 552 {
 553         union acpi_operand_object *obj_desc;
 554         acpi_status status;
 555
 556         ACPI_FUNCTION_TRACE("rs_get_prs_method_data");
 557
 558         /* Parameters guaranteed valid by caller */
 559
 560         /* Execute the method, no parameters */
 561
 562         status = acpi_ut_evaluate_object(handle, METHOD_NAME__PRS,
 563                                          ACPI_BTYPE_BUFFER, &obj_desc);
 564         if (ACPI_FAILURE(status)) {
 565                 return_ACPI_STATUS(status);
 566         }
 567
 568         /*
 569          * Make the call to create a resource linked list from the
 570          * byte stream buffer that comes back from the _CRS method
 571          * execution.
 572          */
 573         status = acpi_rs_create_resource_list(obj_desc, ret_buffer);
 574
 575         /* on exit, we must delete the object returned by evaluate_object */
 576
 577         acpi_ut_remove_reference(obj_desc);
 578         return_ACPI_STATUS(status);
 579 }
 580 #endif                          /*  ACPI_FUTURE_USAGE  */
 581
 582 /*******************************************************************************
 583  *
 584  * FUNCTION:    acpi_rs_get_method_data
 585  *
 586  * PARAMETERS:  Handle          - a handle to the containing object
 587  *              Path            - Path to method, relative to Handle
 588  *              ret_buffer      - a pointer to a buffer structure for the
 589  *                                  results
 590  *
 591  * RETURN:      Status
 592  *
 593  * DESCRIPTION: This function is called to get the _CRS or _PRS value of an
 594  *              object contained in an object specified by the handle passed in
 595  *
 596  *              If the function fails an appropriate status will be returned
 597  *              and the contents of the callers buffer is undefined.
 598  *
 599  ******************************************************************************/
 600
 601 acpi_status
 602 acpi_rs_get_method_data(acpi_handle handle,
 603                         char *path, struct acpi_buffer *ret_buffer)
 604 {
 605         union acpi_operand_object *obj_desc;
 606         acpi_status status;
 607
 608         ACPI_FUNCTION_TRACE("rs_get_method_data");
 609
 610         /* Parameters guaranteed valid by caller */
 611
 612         /* Execute the method, no parameters */
 613
 614         status =
 615             acpi_ut_evaluate_object(handle, path, ACPI_BTYPE_BUFFER, &obj_desc);
 616         if (ACPI_FAILURE(status)) {
 617                 return_ACPI_STATUS(status);
 618         }
 619
 620         /*
 621          * Make the call to create a resource linked list from the
 622          * byte stream buffer that comes back from the method
 623          * execution.
 624          */
 625         status = acpi_rs_create_resource_list(obj_desc, ret_buffer);
 626
 627         /* On exit, we must delete the object returned by evaluate_object */
 628
 629         acpi_ut_remove_reference(obj_desc);
 630         return_ACPI_STATUS(status);
 631 }
 632
 633 /*******************************************************************************
 634  *
 635  * FUNCTION:    acpi_rs_set_srs_method_data
 636  *
 637  * PARAMETERS:  Handle          - a handle to the containing object
 638  *              in_buffer       - a pointer to a buffer structure of the
 639  *                                  parameter
 640  *
 641  * RETURN:      Status
 642  *
 643  * DESCRIPTION: This function is called to set the _SRS of an object contained
 644  *              in an object specified by the handle passed in
 645  *
 646  *              If the function fails an appropriate status will be returned
 647  *              and the contents of the callers buffer is undefined.
 648  *
 649  ******************************************************************************/
 650
 651 acpi_status
 652 acpi_rs_set_srs_method_data(acpi_handle handle, struct acpi_buffer *in_buffer)
 653 {
 654         struct acpi_parameter_info info;
 655         union acpi_operand_object *params[2];
 656         acpi_status status;
 657         struct acpi_buffer buffer;
 658
 659         ACPI_FUNCTION_TRACE("rs_set_srs_method_data");
 660
 661         /* Parameters guaranteed valid by caller */
 662
 663         /*
 664          * The in_buffer parameter will point to a linked list of
 665          * resource parameters.  It needs to be formatted into a
 666          * byte stream to be sent in as an input parameter to _SRS
 667          *
 668          * Convert the linked list into a byte stream
 669          */
 670         buffer.length = ACPI_ALLOCATE_LOCAL_BUFFER;
 671         status = acpi_rs_create_aml_resources(in_buffer->pointer, &buffer);
 672         if (ACPI_FAILURE(status)) {
 673                 return_ACPI_STATUS(status);
 674         }
 675
 676         /* Init the param object */
 677
 678         params[0] = acpi_ut_create_internal_object(ACPI_TYPE_BUFFER);
 679         if (!params[0]) {
 680                 acpi_os_free(buffer.pointer);
 681                 return_ACPI_STATUS(AE_NO_MEMORY);
 682         }
 683
 684         /* Set up the parameter object */
 685
 686         params[0]->buffer.length = (u32) buffer.length;
 687         params[0]->buffer.pointer = buffer.pointer;
 688         params[0]->common.flags = AOPOBJ_DATA_VALID;
 689         params[1] = NULL;
 690
 691         info.node = handle;
 692         info.parameters = params;
 693         info.parameter_type = ACPI_PARAM_ARGS;
 694
 695         /* Execute the method, no return value */
 696
 697         status = acpi_ns_evaluate_relative(METHOD_NAME__SRS, &info);
 698         if (ACPI_SUCCESS(status)) {
 699                 /* Delete any return object (especially if implicit_return is enabled) */
 700
 701                 if (info.return_object) {
 702                         acpi_ut_remove_reference(info.return_object);
 703                 }
 704         }
 705
 706         /* Clean up and return the status from acpi_ns_evaluate_relative */
 707
 708         acpi_ut_remove_reference(params[0]);
 709         return_ACPI_STATUS(status);
 710 }