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  1. /******************************************************************************
  2.  *
  3.  * Module Name: exprep - ACPI AML (p-code) execution - field prep utilities
  4.  *
  5.  *****************************************************************************/
  6.  
  7. /*
  8.  * Copyright (C) 2000 - 2015, 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 "accommon.h"
  46. #include "acinterp.h"
  47. #include "amlcode.h"
  48. #include "acnamesp.h"
  49. #include "acdispat.h"
  50.  
  51. #define _COMPONENT          ACPI_EXECUTER
  52. ACPI_MODULE_NAME("exprep")
  53.  
  54. /* Local prototypes */
  55. static u32
  56. acpi_ex_decode_field_access(union acpi_operand_object *obj_desc,
  57.                             u8 field_flags, u32 * return_byte_alignment);
  58.  
  59. #ifdef ACPI_UNDER_DEVELOPMENT
  60.  
  61. static u32
  62. acpi_ex_generate_access(u32 field_bit_offset,
  63.                         u32 field_bit_length, u32 region_length);
  64.  
  65. /*******************************************************************************
  66.  *
  67.  * FUNCTION:    acpi_ex_generate_access
  68.  *
  69.  * PARAMETERS:  field_bit_offset    - Start of field within parent region/buffer
  70.  *              field_bit_length    - Length of field in bits
  71.  *              region_length       - Length of parent in bytes
  72.  *
  73.  * RETURN:      Field granularity (8, 16, 32 or 64) and
  74.  *              byte_alignment (1, 2, 3, or 4)
  75.  *
  76.  * DESCRIPTION: Generate an optimal access width for fields defined with the
  77.  *              any_acc keyword.
  78.  *
  79.  * NOTE: Need to have the region_length in order to check for boundary
  80.  *       conditions (end-of-region). However, the region_length is a deferred
  81.  *       operation. Therefore, to complete this implementation, the generation
  82.  *       of this access width must be deferred until the region length has
  83.  *       been evaluated.
  84.  *
  85.  ******************************************************************************/
  86.  
  87. static u32
  88. acpi_ex_generate_access(u32 field_bit_offset,
  89.                         u32 field_bit_length, u32 region_length)
  90. {
  91.         u32 field_byte_length;
  92.         u32 field_byte_offset;
  93.         u32 field_byte_end_offset;
  94.         u32 access_byte_width;
  95.         u32 field_start_offset;
  96.         u32 field_end_offset;
  97.         u32 minimum_access_width = 0xFFFFFFFF;
  98.         u32 minimum_accesses = 0xFFFFFFFF;
  99.         u32 accesses;
  100.  
  101.         ACPI_FUNCTION_TRACE(ex_generate_access);
  102.  
  103.         /* Round Field start offset and length to "minimal" byte boundaries */
  104.  
  105.         field_byte_offset = ACPI_DIV_8(ACPI_ROUND_DOWN(field_bit_offset, 8));
  106.         field_byte_end_offset = ACPI_DIV_8(ACPI_ROUND_UP(field_bit_length +
  107.                                                          field_bit_offset, 8));
  108.         field_byte_length = field_byte_end_offset - field_byte_offset;
  109.  
  110.         ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
  111.                           "Bit length %u, Bit offset %u\n",
  112.                           field_bit_length, field_bit_offset));
  113.  
  114.         ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
  115.                           "Byte Length %u, Byte Offset %u, End Offset %u\n",
  116.                           field_byte_length, field_byte_offset,
  117.                           field_byte_end_offset));
  118.  
  119.         /*
  120.          * Iterative search for the maximum access width that is both aligned
  121.          * and does not go beyond the end of the region
  122.          *
  123.          * Start at byte_acc and work upwards to qword_acc max. (1,2,4,8 bytes)
  124.          */
  125.         for (access_byte_width = 1; access_byte_width <= 8;
  126.              access_byte_width <<= 1) {
  127.                 /*
  128.                  * 1) Round end offset up to next access boundary and make sure that
  129.                  *    this does not go beyond the end of the parent region.
  130.                  * 2) When the Access width is greater than the field_byte_length, we
  131.                  *    are done. (This does not optimize for the perfectly aligned
  132.                  *    case yet).
  133.                  */
  134.                 if (ACPI_ROUND_UP(field_byte_end_offset, access_byte_width) <=
  135.                     region_length) {
  136.                         field_start_offset =
  137.                             ACPI_ROUND_DOWN(field_byte_offset,
  138.                                             access_byte_width) /
  139.                             access_byte_width;
  140.  
  141.                         field_end_offset =
  142.                             ACPI_ROUND_UP((field_byte_length +
  143.                                            field_byte_offset),
  144.                                           access_byte_width) /
  145.                             access_byte_width;
  146.  
  147.                         accesses = field_end_offset - field_start_offset;
  148.  
  149.                         ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
  150.                                           "AccessWidth %u end is within region\n",
  151.                                           access_byte_width));
  152.  
  153.                         ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
  154.                                           "Field Start %u, Field End %u -- requires %u accesses\n",
  155.                                           field_start_offset, field_end_offset,
  156.                                           accesses));
  157.  
  158.                         /* Single access is optimal */
  159.  
  160.                         if (accesses <= 1) {
  161.                                 ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
  162.                                                   "Entire field can be accessed with one operation of size %u\n",
  163.                                                   access_byte_width));
  164.                                 return_VALUE(access_byte_width);
  165.                         }
  166.  
  167.                         /*
  168.                          * Fits in the region, but requires more than one read/write.
  169.                          * try the next wider access on next iteration
  170.                          */
  171.                         if (accesses < minimum_accesses) {
  172.                                 minimum_accesses = accesses;
  173.                                 minimum_access_width = access_byte_width;
  174.                         }
  175.                 } else {
  176.                         ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
  177.                                           "AccessWidth %u end is NOT within region\n",
  178.                                           access_byte_width));
  179.                         if (access_byte_width == 1) {
  180.                                 ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
  181.                                                   "Field goes beyond end-of-region!\n"));
  182.  
  183.                                 /* Field does not fit in the region at all */
  184.  
  185.                                 return_VALUE(0);
  186.                         }
  187.  
  188.                         /*
  189.                          * This width goes beyond the end-of-region, back off to
  190.                          * previous access
  191.                          */
  192.                         ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
  193.                                           "Backing off to previous optimal access width of %u\n",
  194.                                           minimum_access_width));
  195.                         return_VALUE(minimum_access_width);
  196.                 }
  197.         }
  198.  
  199.         /*
  200.          * Could not read/write field with one operation,
  201.          * just use max access width
  202.          */
  203.         ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
  204.                           "Cannot access field in one operation, using width 8\n"));
  205.         return_VALUE(8);
  206. }
  207. #endif                          /* ACPI_UNDER_DEVELOPMENT */
  208.  
  209. /*******************************************************************************
  210.  *
  211.  * FUNCTION:    acpi_ex_decode_field_access
  212.  *
  213.  * PARAMETERS:  obj_desc            - Field object
  214.  *              field_flags         - Encoded fieldflags (contains access bits)
  215.  *              return_byte_alignment - Where the byte alignment is returned
  216.  *
  217.  * RETURN:      Field granularity (8, 16, 32 or 64) and
  218.  *              byte_alignment (1, 2, 3, or 4)
  219.  *
  220.  * DESCRIPTION: Decode the access_type bits of a field definition.
  221.  *
  222.  ******************************************************************************/
  223.  
  224. static u32
  225. acpi_ex_decode_field_access(union acpi_operand_object *obj_desc,
  226.                             u8 field_flags, u32 * return_byte_alignment)
  227. {
  228.         u32 access;
  229.         u32 byte_alignment;
  230.         u32 bit_length;
  231.  
  232.         ACPI_FUNCTION_TRACE(ex_decode_field_access);
  233.  
  234.         access = (field_flags & AML_FIELD_ACCESS_TYPE_MASK);
  235.  
  236.         switch (access) {
  237.         case AML_FIELD_ACCESS_ANY:
  238.  
  239. #ifdef ACPI_UNDER_DEVELOPMENT
  240.                 byte_alignment =
  241.                     acpi_ex_generate_access(obj_desc->common_field.
  242.                                             start_field_bit_offset,
  243.                                             obj_desc->common_field.bit_length,
  244.                                             0xFFFFFFFF
  245.                                             /* Temp until we pass region_length as parameter */
  246.                     );
  247.                 bit_length = byte_alignment * 8;
  248. #endif
  249.  
  250.                 byte_alignment = 1;
  251.                 bit_length = 8;
  252.                 break;
  253.  
  254.         case AML_FIELD_ACCESS_BYTE:
  255.         case AML_FIELD_ACCESS_BUFFER:   /* ACPI 2.0 (SMBus Buffer) */
  256.  
  257.                 byte_alignment = 1;
  258.                 bit_length = 8;
  259.                 break;
  260.  
  261.         case AML_FIELD_ACCESS_WORD:
  262.  
  263.                 byte_alignment = 2;
  264.                 bit_length = 16;
  265.                 break;
  266.  
  267.         case AML_FIELD_ACCESS_DWORD:
  268.  
  269.                 byte_alignment = 4;
  270.                 bit_length = 32;
  271.                 break;
  272.  
  273.         case AML_FIELD_ACCESS_QWORD:    /* ACPI 2.0 */
  274.  
  275.                 byte_alignment = 8;
  276.                 bit_length = 64;
  277.                 break;
  278.  
  279.         default:
  280.  
  281.                 /* Invalid field access type */
  282.  
  283.                 ACPI_ERROR((AE_INFO, "Unknown field access type 0x%X", access));
  284.                 return_UINT32(0);
  285.         }
  286.  
  287.         if (obj_desc->common.type == ACPI_TYPE_BUFFER_FIELD) {
  288.                 /*
  289.                  * buffer_field access can be on any byte boundary, so the
  290.                  * byte_alignment is always 1 byte -- regardless of any byte_alignment
  291.                  * implied by the field access type.
  292.                  */
  293.                 byte_alignment = 1;
  294.         }
  295.  
  296.         *return_byte_alignment = byte_alignment;
  297.         return_UINT32(bit_length);
  298. }
  299.  
  300. /*******************************************************************************
  301.  *
  302.  * FUNCTION:    acpi_ex_prep_common_field_object
  303.  *
  304.  * PARAMETERS:  obj_desc            - The field object
  305.  *              field_flags         - Access, lock_rule, and update_rule.
  306.  *                                    The format of a field_flag is described
  307.  *                                    in the ACPI specification
  308.  *              field_attribute     - Special attributes (not used)
  309.  *              field_bit_position  - Field start position
  310.  *              field_bit_length    - Field length in number of bits
  311.  *
  312.  * RETURN:      Status
  313.  *
  314.  * DESCRIPTION: Initialize the areas of the field object that are common
  315.  *              to the various types of fields. Note: This is very "sensitive"
  316.  *              code because we are solving the general case for field
  317.  *              alignment.
  318.  *
  319.  ******************************************************************************/
  320.  
  321. acpi_status
  322. acpi_ex_prep_common_field_object(union acpi_operand_object *obj_desc,
  323.                                  u8 field_flags,
  324.                                  u8 field_attribute,
  325.                                  u32 field_bit_position, u32 field_bit_length)
  326. {
  327.         u32 access_bit_width;
  328.         u32 byte_alignment;
  329.         u32 nearest_byte_address;
  330.  
  331.         ACPI_FUNCTION_TRACE(ex_prep_common_field_object);
  332.  
  333.         /*
  334.          * Note: the structure being initialized is the
  335.          * ACPI_COMMON_FIELD_INFO;  No structure fields outside of the common
  336.          * area are initialized by this procedure.
  337.          */
  338.         obj_desc->common_field.field_flags = field_flags;
  339.         obj_desc->common_field.attribute = field_attribute;
  340.         obj_desc->common_field.bit_length = field_bit_length;
  341.  
  342.         /*
  343.          * Decode the access type so we can compute offsets. The access type gives
  344.          * two pieces of information - the width of each field access and the
  345.          * necessary byte_alignment (address granularity) of the access.
  346.          *
  347.          * For any_acc, the access_bit_width is the largest width that is both
  348.          * necessary and possible in an attempt to access the whole field in one
  349.          * I/O operation. However, for any_acc, the byte_alignment is always one
  350.          * byte.
  351.          *
  352.          * For all Buffer Fields, the byte_alignment is always one byte.
  353.          *
  354.          * For all other access types (Byte, Word, Dword, Qword), the Bitwidth is
  355.          * the same (equivalent) as the byte_alignment.
  356.          */
  357.         access_bit_width = acpi_ex_decode_field_access(obj_desc, field_flags,
  358.                                                        &byte_alignment);
  359.         if (!access_bit_width) {
  360.                 return_ACPI_STATUS(AE_AML_OPERAND_VALUE);
  361.         }
  362.  
  363.         /* Setup width (access granularity) fields (values are: 1, 2, 4, 8) */
  364.  
  365.         obj_desc->common_field.access_byte_width = (u8)
  366.             ACPI_DIV_8(access_bit_width);
  367.  
  368.         /*
  369.          * base_byte_offset is the address of the start of the field within the
  370.          * region. It is the byte address of the first *datum* (field-width data
  371.          * unit) of the field. (i.e., the first datum that contains at least the
  372.          * first *bit* of the field.)
  373.          *
  374.          * Note: byte_alignment is always either equal to the access_bit_width or 8
  375.          * (Byte access), and it defines the addressing granularity of the parent
  376.          * region or buffer.
  377.          */
  378.         nearest_byte_address =
  379.             ACPI_ROUND_BITS_DOWN_TO_BYTES(field_bit_position);
  380.         obj_desc->common_field.base_byte_offset = (u32)
  381.             ACPI_ROUND_DOWN(nearest_byte_address, byte_alignment);
  382.  
  383.         /*
  384.          * start_field_bit_offset is the offset of the first bit of the field within
  385.          * a field datum.
  386.          */
  387.         obj_desc->common_field.start_field_bit_offset = (u8)
  388.             (field_bit_position -
  389.              ACPI_MUL_8(obj_desc->common_field.base_byte_offset));
  390.  
  391.         return_ACPI_STATUS(AE_OK);
  392. }
  393.  
  394. /*******************************************************************************
  395.  *
  396.  * FUNCTION:    acpi_ex_prep_field_value
  397.  *
  398.  * PARAMETERS:  info    - Contains all field creation info
  399.  *
  400.  * RETURN:      Status
  401.  *
  402.  * DESCRIPTION: Construct an object of type union acpi_operand_object with a
  403.  *              subtype of def_field and connect it to the parent Node.
  404.  *
  405.  ******************************************************************************/
  406.  
  407. acpi_status acpi_ex_prep_field_value(struct acpi_create_field_info *info)
  408. {
  409.         union acpi_operand_object *obj_desc;
  410.         union acpi_operand_object *second_desc = NULL;
  411.         acpi_status status;
  412.         u32 access_byte_width;
  413.         u32 type;
  414.  
  415.         ACPI_FUNCTION_TRACE(ex_prep_field_value);
  416.  
  417.         /* Parameter validation */
  418.  
  419.         if (info->field_type != ACPI_TYPE_LOCAL_INDEX_FIELD) {
  420.                 if (!info->region_node) {
  421.                         ACPI_ERROR((AE_INFO, "Null RegionNode"));
  422.                         return_ACPI_STATUS(AE_AML_NO_OPERAND);
  423.                 }
  424.  
  425.                 type = acpi_ns_get_type(info->region_node);
  426.                 if (type != ACPI_TYPE_REGION) {
  427.                         ACPI_ERROR((AE_INFO,
  428.                                     "Needed Region, found type 0x%X (%s)", type,
  429.                                     acpi_ut_get_type_name(type)));
  430.  
  431.                         return_ACPI_STATUS(AE_AML_OPERAND_TYPE);
  432.                 }
  433.         }
  434.  
  435.         /* Allocate a new field object */
  436.  
  437.         obj_desc = acpi_ut_create_internal_object(info->field_type);
  438.         if (!obj_desc) {
  439.                 return_ACPI_STATUS(AE_NO_MEMORY);
  440.         }
  441.  
  442.         /* Initialize areas of the object that are common to all fields */
  443.  
  444.         obj_desc->common_field.node = info->field_node;
  445.         status = acpi_ex_prep_common_field_object(obj_desc,
  446.                                                   info->field_flags,
  447.                                                   info->attribute,
  448.                                                   info->field_bit_position,
  449.                                                   info->field_bit_length);
  450.         if (ACPI_FAILURE(status)) {
  451.                 acpi_ut_delete_object_desc(obj_desc);
  452.                 return_ACPI_STATUS(status);
  453.         }
  454.  
  455.         /* Initialize areas of the object that are specific to the field type */
  456.  
  457.         switch (info->field_type) {
  458.         case ACPI_TYPE_LOCAL_REGION_FIELD:
  459.  
  460.                 obj_desc->field.region_obj =
  461.                     acpi_ns_get_attached_object(info->region_node);
  462.  
  463.                 /* Fields specific to generic_serial_bus fields */
  464.  
  465.                 obj_desc->field.access_length = info->access_length;
  466.  
  467.                 if (info->connection_node) {
  468.                         second_desc = info->connection_node->object;
  469.                         if (!(second_desc->common.flags & AOPOBJ_DATA_VALID)) {
  470.                                 status =
  471.                                     acpi_ds_get_buffer_arguments(second_desc);
  472.                                 if (ACPI_FAILURE(status)) {
  473.                                         acpi_ut_delete_object_desc(obj_desc);
  474.                                         return_ACPI_STATUS(status);
  475.                                 }
  476.                         }
  477.  
  478.                         obj_desc->field.resource_buffer =
  479.                             second_desc->buffer.pointer;
  480.                         obj_desc->field.resource_length =
  481.                             (u16)second_desc->buffer.length;
  482.                 } else if (info->resource_buffer) {
  483.                         obj_desc->field.resource_buffer = info->resource_buffer;
  484.                         obj_desc->field.resource_length = info->resource_length;
  485.                 }
  486.  
  487.                 obj_desc->field.pin_number_index = info->pin_number_index;
  488.  
  489.                 /* Allow full data read from EC address space */
  490.  
  491.                 if ((obj_desc->field.region_obj->region.space_id ==
  492.                      ACPI_ADR_SPACE_EC)
  493.                     && (obj_desc->common_field.bit_length > 8)) {
  494.                         access_byte_width =
  495.                             ACPI_ROUND_BITS_UP_TO_BYTES(obj_desc->common_field.
  496.                                                         bit_length);
  497.  
  498.                         /* Maximum byte width supported is 255 */
  499.  
  500.                         if (access_byte_width < 256) {
  501.                                 obj_desc->common_field.access_byte_width =
  502.                                     (u8)access_byte_width;
  503.                         }
  504.                 }
  505.                 /* An additional reference for the container */
  506.  
  507.                 acpi_ut_add_reference(obj_desc->field.region_obj);
  508.  
  509.                 ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
  510.                                   "RegionField: BitOff %X, Off %X, Gran %X, Region %p\n",
  511.                                   obj_desc->field.start_field_bit_offset,
  512.                                   obj_desc->field.base_byte_offset,
  513.                                   obj_desc->field.access_byte_width,
  514.                                   obj_desc->field.region_obj));
  515.                 break;
  516.  
  517.         case ACPI_TYPE_LOCAL_BANK_FIELD:
  518.  
  519.                 obj_desc->bank_field.value = info->bank_value;
  520.                 obj_desc->bank_field.region_obj =
  521.                     acpi_ns_get_attached_object(info->region_node);
  522.                 obj_desc->bank_field.bank_obj =
  523.                     acpi_ns_get_attached_object(info->register_node);
  524.  
  525.                 /* An additional reference for the attached objects */
  526.  
  527.                 acpi_ut_add_reference(obj_desc->bank_field.region_obj);
  528.                 acpi_ut_add_reference(obj_desc->bank_field.bank_obj);
  529.  
  530.                 ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
  531.                                   "Bank Field: BitOff %X, Off %X, Gran %X, Region %p, BankReg %p\n",
  532.                                   obj_desc->bank_field.start_field_bit_offset,
  533.                                   obj_desc->bank_field.base_byte_offset,
  534.                                   obj_desc->field.access_byte_width,
  535.                                   obj_desc->bank_field.region_obj,
  536.                                   obj_desc->bank_field.bank_obj));
  537.  
  538.                 /*
  539.                  * Remember location in AML stream of the field unit
  540.                  * opcode and operands -- since the bank_value
  541.                  * operands must be evaluated.
  542.                  */
  543.                 second_desc = obj_desc->common.next_object;
  544.                 second_desc->extra.aml_start =
  545.                     ACPI_CAST_PTR(union acpi_parse_object,
  546.                                   info->data_register_node)->named.data;
  547.                 second_desc->extra.aml_length =
  548.                     ACPI_CAST_PTR(union acpi_parse_object,
  549.                                   info->data_register_node)->named.length;
  550.  
  551.                 break;
  552.  
  553.         case ACPI_TYPE_LOCAL_INDEX_FIELD:
  554.  
  555.                 /* Get the Index and Data registers */
  556.  
  557.                 obj_desc->index_field.index_obj =
  558.                     acpi_ns_get_attached_object(info->register_node);
  559.                 obj_desc->index_field.data_obj =
  560.                     acpi_ns_get_attached_object(info->data_register_node);
  561.  
  562.                 if (!obj_desc->index_field.data_obj
  563.                     || !obj_desc->index_field.index_obj) {
  564.                         ACPI_ERROR((AE_INFO,
  565.                                     "Null Index Object during field prep"));
  566.                         acpi_ut_delete_object_desc(obj_desc);
  567.                         return_ACPI_STATUS(AE_AML_INTERNAL);
  568.                 }
  569.  
  570.                 /* An additional reference for the attached objects */
  571.  
  572.                 acpi_ut_add_reference(obj_desc->index_field.data_obj);
  573.                 acpi_ut_add_reference(obj_desc->index_field.index_obj);
  574.  
  575.                 /*
  576.                  * April 2006: Changed to match MS behavior
  577.                  *
  578.                  * The value written to the Index register is the byte offset of the
  579.                  * target field in units of the granularity of the index_field
  580.                  *
  581.                  * Previously, the value was calculated as an index in terms of the
  582.                  * width of the Data register, as below:
  583.                  *
  584.                  *      obj_desc->index_field.Value = (u32)
  585.                  *          (Info->field_bit_position / ACPI_MUL_8 (
  586.                  *              obj_desc->Field.access_byte_width));
  587.                  *
  588.                  * February 2006: Tried value as a byte offset:
  589.                  *      obj_desc->index_field.Value = (u32)
  590.                  *          ACPI_DIV_8 (Info->field_bit_position);
  591.                  */
  592.                 obj_desc->index_field.value =
  593.                     (u32) ACPI_ROUND_DOWN(ACPI_DIV_8(info->field_bit_position),
  594.                                           obj_desc->index_field.
  595.                                           access_byte_width);
  596.  
  597.                 ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
  598.                                   "IndexField: BitOff %X, Off %X, Value %X, Gran %X, Index %p, Data %p\n",
  599.                                   obj_desc->index_field.start_field_bit_offset,
  600.                                   obj_desc->index_field.base_byte_offset,
  601.                                   obj_desc->index_field.value,
  602.                                   obj_desc->field.access_byte_width,
  603.                                   obj_desc->index_field.index_obj,
  604.                                   obj_desc->index_field.data_obj));
  605.                 break;
  606.  
  607.         default:
  608.  
  609.                 /* No other types should get here */
  610.  
  611.                 break;
  612.         }
  613.  
  614.         /*
  615.          * Store the constructed descriptor (obj_desc) into the parent Node,
  616.          * preserving the current type of that named_obj.
  617.          */
  618.         status = acpi_ns_attach_object(info->field_node, obj_desc,
  619.                                        acpi_ns_get_type(info->field_node));
  620.  
  621.         ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
  622.                           "Set NamedObj %p [%4.4s], ObjDesc %p\n",
  623.                           info->field_node,
  624.                           acpi_ut_get_node_name(info->field_node), obj_desc));
  625.  
  626.         /* Remove local reference to the object */
  627.  
  628.         acpi_ut_remove_reference(obj_desc);
  629.         return_ACPI_STATUS(status);
  630. }
  631.