1 /******************************************************************************
2  *
3  * Module Name: exprep - ACPI AML field prep utilities
4  *
5  *****************************************************************************/
6 
7 /******************************************************************************
8  *
9  * 1. Copyright Notice
10  *
11  * Some or all of this work - Copyright (c) 1999 - 2021, Intel Corp.
12  * All rights reserved.
13  *
14  * 2. License
15  *
16  * 2.1. This is your license from Intel Corp. under its intellectual property
17  * rights. You may have additional license terms from the party that provided
18  * you this software, covering your right to use that party's intellectual
19  * property rights.
20  *
21  * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
22  * copy of the source code appearing in this file ("Covered Code") an
23  * irrevocable, perpetual, worldwide license under Intel's copyrights in the
24  * base code distributed originally by Intel ("Original Intel Code") to copy,
25  * make derivatives, distribute, use and display any portion of the Covered
26  * Code in any form, with the right to sublicense such rights; and
27  *
28  * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
29  * license (with the right to sublicense), under only those claims of Intel
30  * patents that are infringed by the Original Intel Code, to make, use, sell,
31  * offer to sell, and import the Covered Code and derivative works thereof
32  * solely to the minimum extent necessary to exercise the above copyright
33  * license, and in no event shall the patent license extend to any additions
34  * to or modifications of the Original Intel Code. No other license or right
35  * is granted directly or by implication, estoppel or otherwise;
36  *
37  * The above copyright and patent license is granted only if the following
38  * conditions are met:
39  *
40  * 3. Conditions
41  *
42  * 3.1. Redistribution of Source with Rights to Further Distribute Source.
43  * Redistribution of source code of any substantial portion of the Covered
44  * Code or modification with rights to further distribute source must include
45  * the above Copyright Notice, the above License, this list of Conditions,
46  * and the following Disclaimer and Export Compliance provision. In addition,
47  * Licensee must cause all Covered Code to which Licensee contributes to
48  * contain a file documenting the changes Licensee made to create that Covered
49  * Code and the date of any change. Licensee must include in that file the
50  * documentation of any changes made by any predecessor Licensee. Licensee
51  * must include a prominent statement that the modification is derived,
52  * directly or indirectly, from Original Intel Code.
53  *
54  * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
55  * Redistribution of source code of any substantial portion of the Covered
56  * Code or modification without rights to further distribute source must
57  * include the following Disclaimer and Export Compliance provision in the
58  * documentation and/or other materials provided with distribution. In
59  * addition, Licensee may not authorize further sublicense of source of any
60  * portion of the Covered Code, and must include terms to the effect that the
61  * license from Licensee to its licensee is limited to the intellectual
62  * property embodied in the software Licensee provides to its licensee, and
63  * not to intellectual property embodied in modifications its licensee may
64  * make.
65  *
66  * 3.3. Redistribution of Executable. Redistribution in executable form of any
67  * substantial portion of the Covered Code or modification must reproduce the
68  * above Copyright Notice, and the following Disclaimer and Export Compliance
69  * provision in the documentation and/or other materials provided with the
70  * distribution.
71  *
72  * 3.4. Intel retains all right, title, and interest in and to the Original
73  * Intel Code.
74  *
75  * 3.5. Neither the name Intel nor any other trademark owned or controlled by
76  * Intel shall be used in advertising or otherwise to promote the sale, use or
77  * other dealings in products derived from or relating to the Covered Code
78  * without prior written authorization from Intel.
79  *
80  * 4. Disclaimer and Export Compliance
81  *
82  * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
83  * HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
84  * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE,
85  * INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY
86  * UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY
87  * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
88  * PARTICULAR PURPOSE.
89  *
90  * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
91  * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
92  * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
93  * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
94  * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
95  * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS
96  * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
97  * LIMITED REMEDY.
98  *
99  * 4.3. Licensee shall not export, either directly or indirectly, any of this
100  * software or system incorporating such software without first obtaining any
101  * required license or other approval from the U. S. Department of Commerce or
102  * any other agency or department of the United States Government. In the
103  * event Licensee exports any such software from the United States or
104  * re-exports any such software from a foreign destination, Licensee shall
105  * ensure that the distribution and export/re-export of the software is in
106  * compliance with all laws, regulations, orders, or other restrictions of the
107  * U.S. Export Administration Regulations. Licensee agrees that neither it nor
108  * any of its subsidiaries will export/re-export any technical data, process,
109  * software, or service, directly or indirectly, to any country for which the
110  * United States government or any agency thereof requires an export license,
111  * other governmental approval, or letter of assurance, without first obtaining
112  * such license, approval or letter.
113  *
114  *****************************************************************************
115  *
116  * Alternatively, you may choose to be licensed under the terms of the
117  * following license:
118  *
119  * Redistribution and use in source and binary forms, with or without
120  * modification, are permitted provided that the following conditions
121  * are met:
122  * 1. Redistributions of source code must retain the above copyright
123  *    notice, this list of conditions, and the following disclaimer,
124  *    without modification.
125  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
126  *    substantially similar to the "NO WARRANTY" disclaimer below
127  *    ("Disclaimer") and any redistribution must be conditioned upon
128  *    including a substantially similar Disclaimer requirement for further
129  *    binary redistribution.
130  * 3. Neither the names of the above-listed copyright holders nor the names
131  *    of any contributors may be used to endorse or promote products derived
132  *    from this software without specific prior written permission.
133  *
134  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
135  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
136  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
137  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
138  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
139  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
140  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
141  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
142  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
143  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
144  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
145  *
146  * Alternatively, you may choose to be licensed under the terms of the
147  * GNU General Public License ("GPL") version 2 as published by the Free
148  * Software Foundation.
149  *
150  *****************************************************************************/
151 
152 #include "acpi.h"
153 #include "accommon.h"
154 #include "acinterp.h"
155 #include "amlcode.h"
156 #include "acnamesp.h"
157 #include "acdispat.h"
158 
159 
160 #define _COMPONENT          ACPI_EXECUTER
161         ACPI_MODULE_NAME    ("exprep")
162 
163 /* Local prototypes */
164 
165 static UINT32
166 AcpiExDecodeFieldAccess (
167     ACPI_OPERAND_OBJECT     *ObjDesc,
168     UINT8                   FieldFlags,
169     UINT32                  *ReturnByteAlignment);
170 
171 
172 #ifdef ACPI_UNDER_DEVELOPMENT
173 
174 static UINT32
175 AcpiExGenerateAccess (
176     UINT32                  FieldBitOffset,
177     UINT32                  FieldBitLength,
178     UINT32                  RegionLength);
179 
180 
181 /*******************************************************************************
182  *
183  * FUNCTION:    AcpiExGenerateAccess
184  *
185  * PARAMETERS:  FieldBitOffset      - Start of field within parent region/buffer
186  *              FieldBitLength      - Length of field in bits
187  *              RegionLength        - Length of parent in bytes
188  *
189  * RETURN:      Field granularity (8, 16, 32 or 64) and
190  *              ByteAlignment (1, 2, 3, or 4)
191  *
192  * DESCRIPTION: Generate an optimal access width for fields defined with the
193  *              AnyAcc keyword.
194  *
195  * NOTE: Need to have the RegionLength in order to check for boundary
196  *       conditions (end-of-region). However, the RegionLength is a deferred
197  *       operation. Therefore, to complete this implementation, the generation
198  *       of this access width must be deferred until the region length has
199  *       been evaluated.
200  *
201  ******************************************************************************/
202 
203 static UINT32
AcpiExGenerateAccess(UINT32 FieldBitOffset,UINT32 FieldBitLength,UINT32 RegionLength)204 AcpiExGenerateAccess (
205     UINT32                  FieldBitOffset,
206     UINT32                  FieldBitLength,
207     UINT32                  RegionLength)
208 {
209     UINT32                  FieldByteLength;
210     UINT32                  FieldByteOffset;
211     UINT32                  FieldByteEndOffset;
212     UINT32                  AccessByteWidth;
213     UINT32                  FieldStartOffset;
214     UINT32                  FieldEndOffset;
215     UINT32                  MinimumAccessWidth = 0xFFFFFFFF;
216     UINT32                  MinimumAccesses = 0xFFFFFFFF;
217     UINT32                  Accesses;
218 
219 
220     ACPI_FUNCTION_TRACE (ExGenerateAccess);
221 
222 
223     /* Round Field start offset and length to "minimal" byte boundaries */
224 
225     FieldByteOffset = ACPI_DIV_8 (
226         ACPI_ROUND_DOWN (FieldBitOffset, 8));
227 
228     FieldByteEndOffset = ACPI_DIV_8 (
229         ACPI_ROUND_UP (FieldBitLength + FieldBitOffset, 8));
230 
231     FieldByteLength = FieldByteEndOffset - FieldByteOffset;
232 
233     ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
234         "Bit length %u, Bit offset %u\n",
235         FieldBitLength, FieldBitOffset));
236 
237     ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
238         "Byte Length %u, Byte Offset %u, End Offset %u\n",
239         FieldByteLength, FieldByteOffset, FieldByteEndOffset));
240 
241     /*
242      * Iterative search for the maximum access width that is both aligned
243      * and does not go beyond the end of the region
244      *
245      * Start at ByteAcc and work upwards to QwordAcc max. (1,2,4,8 bytes)
246      */
247     for (AccessByteWidth = 1; AccessByteWidth <= 8; AccessByteWidth <<= 1)
248     {
249         /*
250          * 1) Round end offset up to next access boundary and make sure that
251          *    this does not go beyond the end of the parent region.
252          * 2) When the Access width is greater than the FieldByteLength, we
253          *    are done. (This does not optimize for the perfectly aligned
254          *    case yet).
255          */
256         if (ACPI_ROUND_UP (FieldByteEndOffset, AccessByteWidth) <=
257             RegionLength)
258         {
259             FieldStartOffset =
260                 ACPI_ROUND_DOWN (FieldByteOffset, AccessByteWidth) /
261                 AccessByteWidth;
262 
263             FieldEndOffset =
264                 ACPI_ROUND_UP ((FieldByteLength + FieldByteOffset),
265                     AccessByteWidth) / AccessByteWidth;
266 
267             Accesses = FieldEndOffset - FieldStartOffset;
268 
269             ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
270                 "AccessWidth %u end is within region\n", AccessByteWidth));
271 
272             ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
273                 "Field Start %u, Field End %u -- requires %u accesses\n",
274                 FieldStartOffset, FieldEndOffset, Accesses));
275 
276             /* Single access is optimal */
277 
278             if (Accesses <= 1)
279             {
280                 ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
281                     "Entire field can be accessed "
282                     "with one operation of size %u\n",
283                     AccessByteWidth));
284                 return_VALUE (AccessByteWidth);
285             }
286 
287             /*
288              * Fits in the region, but requires more than one read/write.
289              * try the next wider access on next iteration
290              */
291             if (Accesses < MinimumAccesses)
292             {
293                 MinimumAccesses = Accesses;
294                 MinimumAccessWidth = AccessByteWidth;
295             }
296         }
297         else
298         {
299             ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
300                 "AccessWidth %u end is NOT within region\n",
301                 AccessByteWidth));
302             if (AccessByteWidth == 1)
303             {
304                 ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
305                     "Field goes beyond end-of-region!\n"));
306 
307                 /* Field does not fit in the region at all */
308 
309                 return_VALUE (0);
310             }
311 
312             /*
313              * This width goes beyond the end-of-region, back off to
314              * previous access
315              */
316             ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
317                 "Backing off to previous optimal access width of %u\n",
318                 MinimumAccessWidth));
319             return_VALUE (MinimumAccessWidth);
320         }
321     }
322 
323     /*
324      * Could not read/write field with one operation,
325      * just use max access width
326      */
327     ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
328         "Cannot access field in one operation, using width 8\n"));
329 
330     return_VALUE (8);
331 }
332 #endif /* ACPI_UNDER_DEVELOPMENT */
333 
334 
335 /*******************************************************************************
336  *
337  * FUNCTION:    AcpiExDecodeFieldAccess
338  *
339  * PARAMETERS:  ObjDesc             - Field object
340  *              FieldFlags          - Encoded fieldflags (contains access bits)
341  *              ReturnByteAlignment - Where the byte alignment is returned
342  *
343  * RETURN:      Field granularity (8, 16, 32 or 64) and
344  *              ByteAlignment (1, 2, 3, or 4)
345  *
346  * DESCRIPTION: Decode the AccessType bits of a field definition.
347  *
348  ******************************************************************************/
349 
350 static UINT32
AcpiExDecodeFieldAccess(ACPI_OPERAND_OBJECT * ObjDesc,UINT8 FieldFlags,UINT32 * ReturnByteAlignment)351 AcpiExDecodeFieldAccess (
352     ACPI_OPERAND_OBJECT     *ObjDesc,
353     UINT8                   FieldFlags,
354     UINT32                  *ReturnByteAlignment)
355 {
356     UINT32                  Access;
357     UINT32                  ByteAlignment;
358     UINT32                  BitLength;
359 
360 
361     ACPI_FUNCTION_TRACE (ExDecodeFieldAccess);
362 
363 
364     Access = (FieldFlags & AML_FIELD_ACCESS_TYPE_MASK);
365 
366     switch (Access)
367     {
368     case AML_FIELD_ACCESS_ANY:
369 
370 #ifdef ACPI_UNDER_DEVELOPMENT
371         ByteAlignment =
372             AcpiExGenerateAccess (ObjDesc->CommonField.StartFieldBitOffset,
373                 ObjDesc->CommonField.BitLength,
374                 0xFFFFFFFF /* Temp until we pass RegionLength as parameter */);
375         BitLength = ByteAlignment * 8;
376 #endif
377 
378         ByteAlignment = 1;
379         BitLength = 8;
380         break;
381 
382     case AML_FIELD_ACCESS_BYTE:
383     case AML_FIELD_ACCESS_BUFFER:   /* ACPI 2.0 (SMBus Buffer) */
384 
385         ByteAlignment = 1;
386         BitLength     = 8;
387         break;
388 
389     case AML_FIELD_ACCESS_WORD:
390 
391         ByteAlignment = 2;
392         BitLength     = 16;
393         break;
394 
395     case AML_FIELD_ACCESS_DWORD:
396 
397         ByteAlignment = 4;
398         BitLength     = 32;
399         break;
400 
401     case AML_FIELD_ACCESS_QWORD:    /* ACPI 2.0 */
402 
403         ByteAlignment = 8;
404         BitLength     = 64;
405         break;
406 
407     default:
408 
409         /* Invalid field access type */
410 
411         ACPI_ERROR ((AE_INFO,
412             "Unknown field access type 0x%X",
413             Access));
414 
415         return_UINT32 (0);
416     }
417 
418     if (ObjDesc->Common.Type == ACPI_TYPE_BUFFER_FIELD)
419     {
420         /*
421          * BufferField access can be on any byte boundary, so the
422          * ByteAlignment is always 1 byte -- regardless of any ByteAlignment
423          * implied by the field access type.
424          */
425         ByteAlignment = 1;
426     }
427 
428     *ReturnByteAlignment = ByteAlignment;
429     return_UINT32 (BitLength);
430 }
431 
432 
433 /*******************************************************************************
434  *
435  * FUNCTION:    AcpiExPrepCommonFieldObject
436  *
437  * PARAMETERS:  ObjDesc             - The field object
438  *              FieldFlags          - Access, LockRule, and UpdateRule.
439  *                                    The format of a FieldFlag is described
440  *                                    in the ACPI specification
441  *              FieldAttribute      - Special attributes (not used)
442  *              FieldBitPosition    - Field start position
443  *              FieldBitLength      - Field length in number of bits
444  *
445  * RETURN:      Status
446  *
447  * DESCRIPTION: Initialize the areas of the field object that are common
448  *              to the various types of fields. Note: This is very "sensitive"
449  *              code because we are solving the general case for field
450  *              alignment.
451  *
452  ******************************************************************************/
453 
454 ACPI_STATUS
AcpiExPrepCommonFieldObject(ACPI_OPERAND_OBJECT * ObjDesc,UINT8 FieldFlags,UINT8 FieldAttribute,UINT32 FieldBitPosition,UINT32 FieldBitLength)455 AcpiExPrepCommonFieldObject (
456     ACPI_OPERAND_OBJECT     *ObjDesc,
457     UINT8                   FieldFlags,
458     UINT8                   FieldAttribute,
459     UINT32                  FieldBitPosition,
460     UINT32                  FieldBitLength)
461 {
462     UINT32                  AccessBitWidth;
463     UINT32                  ByteAlignment;
464     UINT32                  NearestByteAddress;
465 
466 
467     ACPI_FUNCTION_TRACE (ExPrepCommonFieldObject);
468 
469 
470     /*
471      * Note: the structure being initialized is the
472      * ACPI_COMMON_FIELD_INFO;  No structure fields outside of the common
473      * area are initialized by this procedure.
474      */
475     ObjDesc->CommonField.FieldFlags = FieldFlags;
476     ObjDesc->CommonField.Attribute  = FieldAttribute;
477     ObjDesc->CommonField.BitLength  = FieldBitLength;
478 
479     /*
480      * Decode the access type so we can compute offsets. The access type gives
481      * two pieces of information - the width of each field access and the
482      * necessary ByteAlignment (address granularity) of the access.
483      *
484      * For AnyAcc, the AccessBitWidth is the largest width that is both
485      * necessary and possible in an attempt to access the whole field in one
486      * I/O operation. However, for AnyAcc, the ByteAlignment is always one
487      * byte.
488      *
489      * For all Buffer Fields, the ByteAlignment is always one byte.
490      *
491      * For all other access types (Byte, Word, Dword, Qword), the Bitwidth is
492      * the same (equivalent) as the ByteAlignment.
493      */
494     AccessBitWidth = AcpiExDecodeFieldAccess (
495         ObjDesc, FieldFlags, &ByteAlignment);
496     if (!AccessBitWidth)
497     {
498         return_ACPI_STATUS (AE_AML_OPERAND_VALUE);
499     }
500 
501     /* Setup width (access granularity) fields (values are: 1, 2, 4, 8) */
502 
503     ObjDesc->CommonField.AccessByteWidth = (UINT8)
504         ACPI_DIV_8 (AccessBitWidth);
505 
506     /*
507      * BaseByteOffset is the address of the start of the field within the
508      * region. It is the byte address of the first *datum* (field-width data
509      * unit) of the field. (i.e., the first datum that contains at least the
510      * first *bit* of the field.)
511      *
512      * Note: ByteAlignment is always either equal to the AccessBitWidth or 8
513      * (Byte access), and it defines the addressing granularity of the parent
514      * region or buffer.
515      */
516     NearestByteAddress =
517         ACPI_ROUND_BITS_DOWN_TO_BYTES (FieldBitPosition);
518     ObjDesc->CommonField.BaseByteOffset = (UINT32)
519         ACPI_ROUND_DOWN (NearestByteAddress, ByteAlignment);
520 
521     /*
522      * StartFieldBitOffset is the offset of the first bit of the field within
523      * a field datum.
524      */
525     ObjDesc->CommonField.StartFieldBitOffset = (UINT8)
526         (FieldBitPosition - ACPI_MUL_8 (ObjDesc->CommonField.BaseByteOffset));
527 
528     return_ACPI_STATUS (AE_OK);
529 }
530 
531 
532 /*******************************************************************************
533  *
534  * FUNCTION:    AcpiExPrepFieldValue
535  *
536  * PARAMETERS:  Info    - Contains all field creation info
537  *
538  * RETURN:      Status
539  *
540  * DESCRIPTION: Construct an object of type ACPI_OPERAND_OBJECT with a
541  *              subtype of DefField and connect it to the parent Node.
542  *
543  ******************************************************************************/
544 
545 ACPI_STATUS
AcpiExPrepFieldValue(ACPI_CREATE_FIELD_INFO * Info)546 AcpiExPrepFieldValue (
547     ACPI_CREATE_FIELD_INFO  *Info)
548 {
549     ACPI_OPERAND_OBJECT     *ObjDesc;
550     ACPI_OPERAND_OBJECT     *SecondDesc = NULL;
551     ACPI_STATUS             Status;
552     UINT32                  AccessByteWidth;
553     UINT32                  Type;
554 
555 
556     ACPI_FUNCTION_TRACE (ExPrepFieldValue);
557 
558 
559     /* Parameter validation */
560 
561     if (Info->FieldType != ACPI_TYPE_LOCAL_INDEX_FIELD)
562     {
563         if (!Info->RegionNode)
564         {
565             ACPI_ERROR ((AE_INFO, "Null RegionNode"));
566             return_ACPI_STATUS (AE_AML_NO_OPERAND);
567         }
568 
569         Type = AcpiNsGetType (Info->RegionNode);
570         if (Type != ACPI_TYPE_REGION)
571         {
572             ACPI_ERROR ((AE_INFO, "Needed Region, found type 0x%X (%s)",
573                 Type, AcpiUtGetTypeName (Type)));
574 
575             return_ACPI_STATUS (AE_AML_OPERAND_TYPE);
576         }
577     }
578 
579     /* Allocate a new field object */
580 
581     ObjDesc = AcpiUtCreateInternalObject (Info->FieldType);
582     if (!ObjDesc)
583     {
584         return_ACPI_STATUS (AE_NO_MEMORY);
585     }
586 
587     /* Initialize areas of the object that are common to all fields */
588 
589     ObjDesc->CommonField.Node = Info->FieldNode;
590     Status = AcpiExPrepCommonFieldObject (ObjDesc,
591         Info->FieldFlags, Info->Attribute,
592         Info->FieldBitPosition, Info->FieldBitLength);
593     if (ACPI_FAILURE (Status))
594     {
595         AcpiUtDeleteObjectDesc (ObjDesc);
596         return_ACPI_STATUS (Status);
597     }
598 
599     /* Initialize areas of the object that are specific to the field type */
600 
601     switch (Info->FieldType)
602     {
603     case ACPI_TYPE_LOCAL_REGION_FIELD:
604 
605         ObjDesc->Field.RegionObj = AcpiNsGetAttachedObject (Info->RegionNode);
606 
607         /* Fields specific to GenericSerialBus fields */
608 
609         ObjDesc->Field.AccessLength = Info->AccessLength;
610 
611         if (Info->ConnectionNode)
612         {
613             SecondDesc = Info->ConnectionNode->Object;
614             if (!(SecondDesc->Common.Flags & AOPOBJ_DATA_VALID))
615             {
616                 Status = AcpiDsGetBufferArguments (SecondDesc);
617                 if (ACPI_FAILURE (Status))
618                 {
619                     AcpiUtDeleteObjectDesc (ObjDesc);
620                     return_ACPI_STATUS (Status);
621                 }
622             }
623 
624             ObjDesc->Field.ResourceBuffer =
625                 SecondDesc->Buffer.Pointer;
626             ObjDesc->Field.ResourceLength =
627                 (UINT16) SecondDesc->Buffer.Length;
628         }
629         else if (Info->ResourceBuffer)
630         {
631             ObjDesc->Field.ResourceBuffer = Info->ResourceBuffer;
632             ObjDesc->Field.ResourceLength = Info->ResourceLength;
633         }
634 
635         ObjDesc->Field.PinNumberIndex = Info->PinNumberIndex;
636 
637         /* Allow full data read from EC address space */
638 
639         if ((ObjDesc->Field.RegionObj->Region.SpaceId == ACPI_ADR_SPACE_EC) &&
640             (ObjDesc->CommonField.BitLength > 8))
641         {
642             AccessByteWidth = ACPI_ROUND_BITS_UP_TO_BYTES (
643                 ObjDesc->CommonField.BitLength);
644 
645             /* Maximum byte width supported is 255 */
646 
647             if (AccessByteWidth < 256)
648             {
649                 ObjDesc->CommonField.AccessByteWidth =
650                     (UINT8) AccessByteWidth;
651             }
652         }
653 
654         ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
655             "RegionField: BitOff %X, Off %X, Gran %X, Region %p\n",
656             ObjDesc->Field.StartFieldBitOffset,
657             ObjDesc->Field.BaseByteOffset,
658             ObjDesc->Field.AccessByteWidth,
659             ObjDesc->Field.RegionObj));
660         break;
661 
662     case ACPI_TYPE_LOCAL_BANK_FIELD:
663 
664         ObjDesc->BankField.Value = Info->BankValue;
665         ObjDesc->BankField.RegionObj =
666             AcpiNsGetAttachedObject (Info->RegionNode);
667         ObjDesc->BankField.BankObj =
668             AcpiNsGetAttachedObject (Info->RegisterNode);
669 
670         /* An additional reference for the attached objects */
671 
672         AcpiUtAddReference (ObjDesc->BankField.RegionObj);
673         AcpiUtAddReference (ObjDesc->BankField.BankObj);
674 
675         ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
676             "Bank Field: BitOff %X, Off %X, Gran %X, Region %p, BankReg %p\n",
677             ObjDesc->BankField.StartFieldBitOffset,
678             ObjDesc->BankField.BaseByteOffset,
679             ObjDesc->Field.AccessByteWidth,
680             ObjDesc->BankField.RegionObj,
681             ObjDesc->BankField.BankObj));
682 
683         /*
684          * Remember location in AML stream of the field unit
685          * opcode and operands -- since the BankValue
686          * operands must be evaluated.
687          */
688         SecondDesc = ObjDesc->Common.NextObject;
689         SecondDesc->Extra.AmlStart = ACPI_CAST_PTR (ACPI_PARSE_OBJECT,
690             Info->DataRegisterNode)->Named.Data;
691         SecondDesc->Extra.AmlLength = ACPI_CAST_PTR (ACPI_PARSE_OBJECT,
692             Info->DataRegisterNode)->Named.Length;
693 
694         break;
695 
696     case ACPI_TYPE_LOCAL_INDEX_FIELD:
697 
698         /* Get the Index and Data registers */
699 
700         ObjDesc->IndexField.IndexObj =
701             AcpiNsGetAttachedObject (Info->RegisterNode);
702         ObjDesc->IndexField.DataObj =
703             AcpiNsGetAttachedObject (Info->DataRegisterNode);
704 
705         if (!ObjDesc->IndexField.DataObj || !ObjDesc->IndexField.IndexObj)
706         {
707             ACPI_ERROR ((AE_INFO, "Null Index Object during field prep"));
708             AcpiUtDeleteObjectDesc (ObjDesc);
709             return_ACPI_STATUS (AE_AML_INTERNAL);
710         }
711 
712         /* An additional reference for the attached objects */
713 
714         AcpiUtAddReference (ObjDesc->IndexField.DataObj);
715         AcpiUtAddReference (ObjDesc->IndexField.IndexObj);
716 
717         /*
718          * April 2006: Changed to match MS behavior
719          *
720          * The value written to the Index register is the byte offset of the
721          * target field in units of the granularity of the IndexField
722          *
723          * Previously, the value was calculated as an index in terms of the
724          * width of the Data register, as below:
725          *
726          *      ObjDesc->IndexField.Value = (UINT32)
727          *          (Info->FieldBitPosition / ACPI_MUL_8 (
728          *              ObjDesc->Field.AccessByteWidth));
729          *
730          * February 2006: Tried value as a byte offset:
731          *      ObjDesc->IndexField.Value = (UINT32)
732          *          ACPI_DIV_8 (Info->FieldBitPosition);
733          */
734         ObjDesc->IndexField.Value = (UINT32) ACPI_ROUND_DOWN (
735             ACPI_DIV_8 (Info->FieldBitPosition),
736             ObjDesc->IndexField.AccessByteWidth);
737 
738         ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
739             "IndexField: BitOff %X, Off %X, Value %X, "
740             "Gran %X, Index %p, Data %p\n",
741             ObjDesc->IndexField.StartFieldBitOffset,
742             ObjDesc->IndexField.BaseByteOffset,
743             ObjDesc->IndexField.Value,
744             ObjDesc->Field.AccessByteWidth,
745             ObjDesc->IndexField.IndexObj,
746             ObjDesc->IndexField.DataObj));
747         break;
748 
749     default:
750 
751         /* No other types should get here */
752 
753         break;
754     }
755 
756     /*
757      * Store the constructed descriptor (ObjDesc) into the parent Node,
758      * preserving the current type of that NamedObj.
759      */
760     Status = AcpiNsAttachObject (
761         Info->FieldNode, ObjDesc, AcpiNsGetType (Info->FieldNode));
762 
763     ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
764         "Set NamedObj %p [%4.4s], ObjDesc %p\n",
765         Info->FieldNode, AcpiUtGetNodeName (Info->FieldNode), ObjDesc));
766 
767     /* Remove local reference to the object */
768 
769     AcpiUtRemoveReference (ObjDesc);
770     return_ACPI_STATUS (Status);
771 }
772