exprep.c revision 193267
1
2/******************************************************************************
3 *
4 * Module Name: exprep - ACPI AML (p-code) execution - field prep utilities
5 *
6 *****************************************************************************/
7
8/******************************************************************************
9 *
10 * 1. Copyright Notice
11 *
12 * Some or all of this work - Copyright (c) 1999 - 2009, Intel Corp.
13 * All rights reserved.
14 *
15 * 2. License
16 *
17 * 2.1. This is your license from Intel Corp. under its intellectual property
18 * rights.  You may have additional license terms from the party that provided
19 * you this software, covering your right to use that party's intellectual
20 * property rights.
21 *
22 * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
23 * copy of the source code appearing in this file ("Covered Code") an
24 * irrevocable, perpetual, worldwide license under Intel's copyrights in the
25 * base code distributed originally by Intel ("Original Intel Code") to copy,
26 * make derivatives, distribute, use and display any portion of the Covered
27 * Code in any form, with the right to sublicense such rights; and
28 *
29 * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
30 * license (with the right to sublicense), under only those claims of Intel
31 * patents that are infringed by the Original Intel Code, to make, use, sell,
32 * offer to sell, and import the Covered Code and derivative works thereof
33 * solely to the minimum extent necessary to exercise the above copyright
34 * license, and in no event shall the patent license extend to any additions
35 * to or modifications of the Original Intel Code.  No other license or right
36 * is granted directly or by implication, estoppel or otherwise;
37 *
38 * The above copyright and patent license is granted only if the following
39 * conditions are met:
40 *
41 * 3. Conditions
42 *
43 * 3.1. Redistribution of Source with Rights to Further Distribute Source.
44 * Redistribution of source code of any substantial portion of the Covered
45 * Code or modification with rights to further distribute source must include
46 * the above Copyright Notice, the above License, this list of Conditions,
47 * and the following Disclaimer and Export Compliance provision.  In addition,
48 * Licensee must cause all Covered Code to which Licensee contributes to
49 * contain a file documenting the changes Licensee made to create that Covered
50 * Code and the date of any change.  Licensee must include in that file the
51 * documentation of any changes made by any predecessor Licensee.  Licensee
52 * must include a prominent statement that the modification is derived,
53 * directly or indirectly, from Original Intel Code.
54 *
55 * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
56 * Redistribution of source code of any substantial portion of the Covered
57 * Code or modification without rights to further distribute source must
58 * include the following Disclaimer and Export Compliance provision in the
59 * documentation and/or other materials provided with distribution.  In
60 * addition, Licensee may not authorize further sublicense of source of any
61 * portion of the Covered Code, and must include terms to the effect that the
62 * license from Licensee to its licensee is limited to the intellectual
63 * property embodied in the software Licensee provides to its licensee, and
64 * not to intellectual property embodied in modifications its licensee may
65 * make.
66 *
67 * 3.3. Redistribution of Executable. Redistribution in executable form of any
68 * substantial portion of the Covered Code or modification must reproduce the
69 * above Copyright Notice, and the following Disclaimer and Export Compliance
70 * provision in the documentation and/or other materials provided with the
71 * distribution.
72 *
73 * 3.4. Intel retains all right, title, and interest in and to the Original
74 * Intel Code.
75 *
76 * 3.5. Neither the name Intel nor any other trademark owned or controlled by
77 * Intel shall be used in advertising or otherwise to promote the sale, use or
78 * other dealings in products derived from or relating to the Covered Code
79 * without prior written authorization from Intel.
80 *
81 * 4. Disclaimer and Export Compliance
82 *
83 * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
84 * HERE.  ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
85 * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT,  ASSISTANCE,
86 * INSTALLATION, TRAINING OR OTHER SERVICES.  INTEL WILL NOT PROVIDE ANY
87 * UPDATES, ENHANCEMENTS OR EXTENSIONS.  INTEL SPECIFICALLY DISCLAIMS ANY
88 * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
89 * PARTICULAR PURPOSE.
90 *
91 * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
92 * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
93 * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
94 * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
95 * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
96 * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.  THESE LIMITATIONS
97 * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
98 * LIMITED REMEDY.
99 *
100 * 4.3. Licensee shall not export, either directly or indirectly, any of this
101 * software or system incorporating such software without first obtaining any
102 * required license or other approval from the U. S. Department of Commerce or
103 * any other agency or department of the United States Government.  In the
104 * event Licensee exports any such software from the United States or
105 * re-exports any such software from a foreign destination, Licensee shall
106 * ensure that the distribution and export/re-export of the software is in
107 * compliance with all laws, regulations, orders, or other restrictions of the
108 * U.S. Export Administration Regulations. Licensee agrees that neither it nor
109 * any of its subsidiaries will export/re-export any technical data, process,
110 * software, or service, directly or indirectly, to any country for which the
111 * United States government or any agency thereof requires an export license,
112 * other governmental approval, or letter of assurance, without first obtaining
113 * such license, approval or letter.
114 *
115 *****************************************************************************/
116
117#define __EXPREP_C__
118
119#include "acpi.h"
120#include "accommon.h"
121#include "acinterp.h"
122#include "amlcode.h"
123#include "acnamesp.h"
124
125
126#define _COMPONENT          ACPI_EXECUTER
127        ACPI_MODULE_NAME    ("exprep")
128
129/* Local prototypes */
130
131static UINT32
132AcpiExDecodeFieldAccess (
133    ACPI_OPERAND_OBJECT     *ObjDesc,
134    UINT8                   FieldFlags,
135    UINT32                  *ReturnByteAlignment);
136
137
138#ifdef ACPI_UNDER_DEVELOPMENT
139
140static UINT32
141AcpiExGenerateAccess (
142    UINT32                  FieldBitOffset,
143    UINT32                  FieldBitLength,
144    UINT32                  RegionLength);
145
146/*******************************************************************************
147 *
148 * FUNCTION:    AcpiExGenerateAccess
149 *
150 * PARAMETERS:  FieldBitOffset      - Start of field within parent region/buffer
151 *              FieldBitLength      - Length of field in bits
152 *              RegionLength        - Length of parent in bytes
153 *
154 * RETURN:      Field granularity (8, 16, 32 or 64) and
155 *              ByteAlignment (1, 2, 3, or 4)
156 *
157 * DESCRIPTION: Generate an optimal access width for fields defined with the
158 *              AnyAcc keyword.
159 *
160 * NOTE: Need to have the RegionLength in order to check for boundary
161 *       conditions (end-of-region).  However, the RegionLength is a deferred
162 *       operation.  Therefore, to complete this implementation, the generation
163 *       of this access width must be deferred until the region length has
164 *       been evaluated.
165 *
166 ******************************************************************************/
167
168static UINT32
169AcpiExGenerateAccess (
170    UINT32                  FieldBitOffset,
171    UINT32                  FieldBitLength,
172    UINT32                  RegionLength)
173{
174    UINT32                  FieldByteLength;
175    UINT32                  FieldByteOffset;
176    UINT32                  FieldByteEndOffset;
177    UINT32                  AccessByteWidth;
178    UINT32                  FieldStartOffset;
179    UINT32                  FieldEndOffset;
180    UINT32                  MinimumAccessWidth = 0xFFFFFFFF;
181    UINT32                  MinimumAccesses = 0xFFFFFFFF;
182    UINT32                  Accesses;
183
184
185    ACPI_FUNCTION_TRACE (ExGenerateAccess);
186
187
188    /* Round Field start offset and length to "minimal" byte boundaries */
189
190    FieldByteOffset    = ACPI_DIV_8 (ACPI_ROUND_DOWN (FieldBitOffset, 8));
191    FieldByteEndOffset = ACPI_DIV_8 (ACPI_ROUND_UP   (FieldBitLength +
192                                                      FieldBitOffset, 8));
193    FieldByteLength    = FieldByteEndOffset - FieldByteOffset;
194
195    ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
196            "Bit length %d, Bit offset %d\n",
197            FieldBitLength, FieldBitOffset));
198
199    ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
200            "Byte Length %d, Byte Offset %d, End Offset %d\n",
201            FieldByteLength, FieldByteOffset, FieldByteEndOffset));
202
203    /*
204     * Iterative search for the maximum access width that is both aligned
205     * and does not go beyond the end of the region
206     *
207     * Start at ByteAcc and work upwards to QwordAcc max. (1,2,4,8 bytes)
208     */
209    for (AccessByteWidth = 1; AccessByteWidth <= 8; AccessByteWidth <<= 1)
210    {
211        /*
212         * 1) Round end offset up to next access boundary and make sure that
213         *    this does not go beyond the end of the parent region.
214         * 2) When the Access width is greater than the FieldByteLength, we
215         *    are done. (This does not optimize for the perfectly aligned
216         *    case yet).
217         */
218        if (ACPI_ROUND_UP (FieldByteEndOffset, AccessByteWidth) <= RegionLength)
219        {
220            FieldStartOffset =
221                ACPI_ROUND_DOWN (FieldByteOffset, AccessByteWidth) /
222                AccessByteWidth;
223
224            FieldEndOffset =
225                ACPI_ROUND_UP ((FieldByteLength + FieldByteOffset),
226                    AccessByteWidth) / AccessByteWidth;
227
228            Accesses = FieldEndOffset - FieldStartOffset;
229
230            ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
231                    "AccessWidth %d end is within region\n", AccessByteWidth));
232
233            ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
234                    "Field Start %d, Field End %d -- requires %d accesses\n",
235                    FieldStartOffset, FieldEndOffset, Accesses));
236
237            /* Single access is optimal */
238
239            if (Accesses <= 1)
240            {
241                ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
242                    "Entire field can be accessed with one operation of size %d\n",
243                    AccessByteWidth));
244                return_VALUE (AccessByteWidth);
245            }
246
247            /*
248             * Fits in the region, but requires more than one read/write.
249             * try the next wider access on next iteration
250             */
251            if (Accesses < MinimumAccesses)
252            {
253                MinimumAccesses    = Accesses;
254                MinimumAccessWidth = AccessByteWidth;
255            }
256        }
257        else
258        {
259            ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
260                "AccessWidth %d end is NOT within region\n", AccessByteWidth));
261            if (AccessByteWidth == 1)
262            {
263                ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
264                        "Field goes beyond end-of-region!\n"));
265
266                /* Field does not fit in the region at all */
267
268                return_VALUE (0);
269            }
270
271            /*
272             * This width goes beyond the end-of-region, back off to
273             * previous access
274             */
275            ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
276                    "Backing off to previous optimal access width of %d\n",
277                    MinimumAccessWidth));
278            return_VALUE (MinimumAccessWidth);
279        }
280    }
281
282    /*
283     * Could not read/write field with one operation,
284     * just use max access width
285     */
286    ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
287            "Cannot access field in one operation, using width 8\n"));
288    return_VALUE (8);
289}
290#endif /* ACPI_UNDER_DEVELOPMENT */
291
292
293/*******************************************************************************
294 *
295 * FUNCTION:    AcpiExDecodeFieldAccess
296 *
297 * PARAMETERS:  ObjDesc             - Field object
298 *              FieldFlags          - Encoded fieldflags (contains access bits)
299 *              ReturnByteAlignment - Where the byte alignment is returned
300 *
301 * RETURN:      Field granularity (8, 16, 32 or 64) and
302 *              ByteAlignment (1, 2, 3, or 4)
303 *
304 * DESCRIPTION: Decode the AccessType bits of a field definition.
305 *
306 ******************************************************************************/
307
308static UINT32
309AcpiExDecodeFieldAccess (
310    ACPI_OPERAND_OBJECT     *ObjDesc,
311    UINT8                   FieldFlags,
312    UINT32                  *ReturnByteAlignment)
313{
314    UINT32                  Access;
315    UINT32                  ByteAlignment;
316    UINT32                  BitLength;
317
318
319    ACPI_FUNCTION_TRACE (ExDecodeFieldAccess);
320
321
322    Access = (FieldFlags & AML_FIELD_ACCESS_TYPE_MASK);
323
324    switch (Access)
325    {
326    case AML_FIELD_ACCESS_ANY:
327
328#ifdef ACPI_UNDER_DEVELOPMENT
329        ByteAlignment =
330            AcpiExGenerateAccess (ObjDesc->CommonField.StartFieldBitOffset,
331                ObjDesc->CommonField.BitLength,
332                0xFFFFFFFF /* Temp until we pass RegionLength as parameter */);
333        BitLength = ByteAlignment * 8;
334#endif
335
336        ByteAlignment = 1;
337        BitLength = 8;
338        break;
339
340    case AML_FIELD_ACCESS_BYTE:
341    case AML_FIELD_ACCESS_BUFFER:   /* ACPI 2.0 (SMBus Buffer) */
342        ByteAlignment = 1;
343        BitLength     = 8;
344        break;
345
346    case AML_FIELD_ACCESS_WORD:
347        ByteAlignment = 2;
348        BitLength     = 16;
349        break;
350
351    case AML_FIELD_ACCESS_DWORD:
352        ByteAlignment = 4;
353        BitLength     = 32;
354        break;
355
356    case AML_FIELD_ACCESS_QWORD:    /* ACPI 2.0 */
357        ByteAlignment = 8;
358        BitLength     = 64;
359        break;
360
361    default:
362        /* Invalid field access type */
363
364        ACPI_ERROR ((AE_INFO,
365            "Unknown field access type %X",
366            Access));
367        return_UINT32 (0);
368    }
369
370    if (ObjDesc->Common.Type == ACPI_TYPE_BUFFER_FIELD)
371    {
372        /*
373         * BufferField access can be on any byte boundary, so the
374         * ByteAlignment is always 1 byte -- regardless of any ByteAlignment
375         * implied by the field access type.
376         */
377        ByteAlignment = 1;
378    }
379
380    *ReturnByteAlignment = ByteAlignment;
381    return_UINT32 (BitLength);
382}
383
384
385/*******************************************************************************
386 *
387 * FUNCTION:    AcpiExPrepCommonFieldObject
388 *
389 * PARAMETERS:  ObjDesc             - The field object
390 *              FieldFlags          - Access, LockRule, and UpdateRule.
391 *                                    The format of a FieldFlag is described
392 *                                    in the ACPI specification
393 *              FieldAttribute      - Special attributes (not used)
394 *              FieldBitPosition    - Field start position
395 *              FieldBitLength      - Field length in number of bits
396 *
397 * RETURN:      Status
398 *
399 * DESCRIPTION: Initialize the areas of the field object that are common
400 *              to the various types of fields.  Note: This is very "sensitive"
401 *              code because we are solving the general case for field
402 *              alignment.
403 *
404 ******************************************************************************/
405
406ACPI_STATUS
407AcpiExPrepCommonFieldObject (
408    ACPI_OPERAND_OBJECT     *ObjDesc,
409    UINT8                   FieldFlags,
410    UINT8                   FieldAttribute,
411    UINT32                  FieldBitPosition,
412    UINT32                  FieldBitLength)
413{
414    UINT32                  AccessBitWidth;
415    UINT32                  ByteAlignment;
416    UINT32                  NearestByteAddress;
417
418
419    ACPI_FUNCTION_TRACE (ExPrepCommonFieldObject);
420
421
422    /*
423     * Note: the structure being initialized is the
424     * ACPI_COMMON_FIELD_INFO;  No structure fields outside of the common
425     * area are initialized by this procedure.
426     */
427    ObjDesc->CommonField.FieldFlags = FieldFlags;
428    ObjDesc->CommonField.Attribute  = FieldAttribute;
429    ObjDesc->CommonField.BitLength  = FieldBitLength;
430
431    /*
432     * Decode the access type so we can compute offsets.  The access type gives
433     * two pieces of information - the width of each field access and the
434     * necessary ByteAlignment (address granularity) of the access.
435     *
436     * For AnyAcc, the AccessBitWidth is the largest width that is both
437     * necessary and possible in an attempt to access the whole field in one
438     * I/O operation.  However, for AnyAcc, the ByteAlignment is always one
439     * byte.
440     *
441     * For all Buffer Fields, the ByteAlignment is always one byte.
442     *
443     * For all other access types (Byte, Word, Dword, Qword), the Bitwidth is
444     * the same (equivalent) as the ByteAlignment.
445     */
446    AccessBitWidth = AcpiExDecodeFieldAccess (ObjDesc, FieldFlags,
447                                &ByteAlignment);
448    if (!AccessBitWidth)
449    {
450        return_ACPI_STATUS (AE_AML_OPERAND_VALUE);
451    }
452
453    /* Setup width (access granularity) fields */
454
455    ObjDesc->CommonField.AccessByteWidth = (UINT8)
456            ACPI_DIV_8 (AccessBitWidth);            /* 1,  2,  4,  8 */
457
458    ObjDesc->CommonField.AccessBitWidth = (UINT8) AccessBitWidth;
459
460    /*
461     * BaseByteOffset is the address of the start of the field within the
462     * region.  It is the byte address of the first *datum* (field-width data
463     * unit) of the field. (i.e., the first datum that contains at least the
464     * first *bit* of the field.)
465     *
466     * Note: ByteAlignment is always either equal to the AccessBitWidth or 8
467     * (Byte access), and it defines the addressing granularity of the parent
468     * region or buffer.
469     */
470    NearestByteAddress =
471            ACPI_ROUND_BITS_DOWN_TO_BYTES (FieldBitPosition);
472    ObjDesc->CommonField.BaseByteOffset = (UINT32)
473            ACPI_ROUND_DOWN (NearestByteAddress, ByteAlignment);
474
475    /*
476     * StartFieldBitOffset is the offset of the first bit of the field within
477     * a field datum.
478     */
479    ObjDesc->CommonField.StartFieldBitOffset = (UINT8)
480        (FieldBitPosition - ACPI_MUL_8 (ObjDesc->CommonField.BaseByteOffset));
481
482    /*
483     * Does the entire field fit within a single field access element? (datum)
484     * (i.e., without crossing a datum boundary)
485     */
486    if ((ObjDesc->CommonField.StartFieldBitOffset + FieldBitLength) <=
487            (UINT16) AccessBitWidth)
488    {
489        ObjDesc->Common.Flags |= AOPOBJ_SINGLE_DATUM;
490    }
491
492    return_ACPI_STATUS (AE_OK);
493}
494
495
496/*******************************************************************************
497 *
498 * FUNCTION:    AcpiExPrepFieldValue
499 *
500 * PARAMETERS:  Info    - Contains all field creation info
501 *
502 * RETURN:      Status
503 *
504 * DESCRIPTION: Construct an ACPI_OPERAND_OBJECT of type DefField and
505 *              connect it to the parent Node.
506 *
507 ******************************************************************************/
508
509ACPI_STATUS
510AcpiExPrepFieldValue (
511    ACPI_CREATE_FIELD_INFO  *Info)
512{
513    ACPI_OPERAND_OBJECT     *ObjDesc;
514    ACPI_OPERAND_OBJECT     *SecondDesc = NULL;
515    UINT32                  Type;
516    ACPI_STATUS             Status;
517
518
519    ACPI_FUNCTION_TRACE (ExPrepFieldValue);
520
521
522    /* Parameter validation */
523
524    if (Info->FieldType != ACPI_TYPE_LOCAL_INDEX_FIELD)
525    {
526        if (!Info->RegionNode)
527        {
528            ACPI_ERROR ((AE_INFO, "Null RegionNode"));
529            return_ACPI_STATUS (AE_AML_NO_OPERAND);
530        }
531
532        Type = AcpiNsGetType (Info->RegionNode);
533        if (Type != ACPI_TYPE_REGION)
534        {
535            ACPI_ERROR ((AE_INFO,
536                "Needed Region, found type %X (%s)",
537                Type, AcpiUtGetTypeName (Type)));
538
539            return_ACPI_STATUS (AE_AML_OPERAND_TYPE);
540        }
541    }
542
543    /* Allocate a new field object */
544
545    ObjDesc = AcpiUtCreateInternalObject (Info->FieldType);
546    if (!ObjDesc)
547    {
548        return_ACPI_STATUS (AE_NO_MEMORY);
549    }
550
551    /* Initialize areas of the object that are common to all fields */
552
553    ObjDesc->CommonField.Node = Info->FieldNode;
554    Status = AcpiExPrepCommonFieldObject (ObjDesc, Info->FieldFlags,
555                Info->Attribute, Info->FieldBitPosition, Info->FieldBitLength);
556    if (ACPI_FAILURE (Status))
557    {
558        AcpiUtDeleteObjectDesc (ObjDesc);
559        return_ACPI_STATUS (Status);
560    }
561
562    /* Initialize areas of the object that are specific to the field type */
563
564    switch (Info->FieldType)
565    {
566    case ACPI_TYPE_LOCAL_REGION_FIELD:
567
568        ObjDesc->Field.RegionObj = AcpiNsGetAttachedObject (Info->RegionNode);
569
570        /* An additional reference for the container */
571
572        AcpiUtAddReference (ObjDesc->Field.RegionObj);
573
574        ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
575            "RegionField: BitOff %X, Off %X, Gran %X, Region %p\n",
576            ObjDesc->Field.StartFieldBitOffset, ObjDesc->Field.BaseByteOffset,
577            ObjDesc->Field.AccessByteWidth, ObjDesc->Field.RegionObj));
578        break;
579
580
581    case ACPI_TYPE_LOCAL_BANK_FIELD:
582
583        ObjDesc->BankField.Value     = Info->BankValue;
584        ObjDesc->BankField.RegionObj = AcpiNsGetAttachedObject (
585                                            Info->RegionNode);
586        ObjDesc->BankField.BankObj   = AcpiNsGetAttachedObject (
587                                            Info->RegisterNode);
588
589        /* An additional reference for the attached objects */
590
591        AcpiUtAddReference (ObjDesc->BankField.RegionObj);
592        AcpiUtAddReference (ObjDesc->BankField.BankObj);
593
594        ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
595            "Bank Field: BitOff %X, Off %X, Gran %X, Region %p, BankReg %p\n",
596            ObjDesc->BankField.StartFieldBitOffset,
597            ObjDesc->BankField.BaseByteOffset,
598            ObjDesc->Field.AccessByteWidth,
599            ObjDesc->BankField.RegionObj,
600            ObjDesc->BankField.BankObj));
601
602        /*
603         * Remember location in AML stream of the field unit
604         * opcode and operands -- since the BankValue
605         * operands must be evaluated.
606         */
607        SecondDesc                  = ObjDesc->Common.NextObject;
608        SecondDesc->Extra.AmlStart  = ACPI_CAST_PTR (ACPI_PARSE_OBJECT, Info->DataRegisterNode)->Named.Data;
609        SecondDesc->Extra.AmlLength = ACPI_CAST_PTR (ACPI_PARSE_OBJECT, Info->DataRegisterNode)->Named.Length;
610
611        break;
612
613
614    case ACPI_TYPE_LOCAL_INDEX_FIELD:
615
616        /* Get the Index and Data registers */
617
618        ObjDesc->IndexField.IndexObj = AcpiNsGetAttachedObject (
619                                            Info->RegisterNode);
620        ObjDesc->IndexField.DataObj  = AcpiNsGetAttachedObject (
621                                            Info->DataRegisterNode);
622
623        if (!ObjDesc->IndexField.DataObj || !ObjDesc->IndexField.IndexObj)
624        {
625            ACPI_ERROR ((AE_INFO, "Null Index Object during field prep"));
626            AcpiUtDeleteObjectDesc (ObjDesc);
627            return_ACPI_STATUS (AE_AML_INTERNAL);
628        }
629
630        /* An additional reference for the attached objects */
631
632        AcpiUtAddReference (ObjDesc->IndexField.DataObj);
633        AcpiUtAddReference (ObjDesc->IndexField.IndexObj);
634
635        /*
636         * April 2006: Changed to match MS behavior
637         *
638         * The value written to the Index register is the byte offset of the
639         * target field in units of the granularity of the IndexField
640         *
641         * Previously, the value was calculated as an index in terms of the
642         * width of the Data register, as below:
643         *
644         *      ObjDesc->IndexField.Value = (UINT32)
645         *          (Info->FieldBitPosition / ACPI_MUL_8 (
646         *              ObjDesc->Field.AccessByteWidth));
647         *
648         * February 2006: Tried value as a byte offset:
649         *      ObjDesc->IndexField.Value = (UINT32)
650         *          ACPI_DIV_8 (Info->FieldBitPosition);
651         */
652        ObjDesc->IndexField.Value = (UINT32) ACPI_ROUND_DOWN (
653            ACPI_DIV_8 (Info->FieldBitPosition),
654            ObjDesc->IndexField.AccessByteWidth);
655
656        ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
657            "IndexField: BitOff %X, Off %X, Value %X, Gran %X, Index %p, Data %p\n",
658            ObjDesc->IndexField.StartFieldBitOffset,
659            ObjDesc->IndexField.BaseByteOffset,
660            ObjDesc->IndexField.Value,
661            ObjDesc->Field.AccessByteWidth,
662            ObjDesc->IndexField.IndexObj,
663            ObjDesc->IndexField.DataObj));
664        break;
665
666    default:
667        /* No other types should get here */
668        break;
669    }
670
671    /*
672     * Store the constructed descriptor (ObjDesc) into the parent Node,
673     * preserving the current type of that NamedObj.
674     */
675    Status = AcpiNsAttachObject (Info->FieldNode, ObjDesc,
676                    AcpiNsGetType (Info->FieldNode));
677
678    ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD, "Set NamedObj %p [%4.4s], ObjDesc %p\n",
679            Info->FieldNode, AcpiUtGetNodeName (Info->FieldNode), ObjDesc));
680
681    /* Remove local reference to the object */
682
683    AcpiUtRemoveReference (ObjDesc);
684    return_ACPI_STATUS (Status);
685}
686
687