summaryrefslogtreecommitdiff
path: root/drivers/acpi/executer/exfldio.c
blob: 40f0bee6faa57a25989e28573d1e2ca6b953013a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
/******************************************************************************
 *
 * Module Name: exfldio - Aml Field I/O
 *
 *****************************************************************************/

/*
 * Copyright (C) 2000 - 2006, R. Byron Moore
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 */

#include <acpi/acpi.h>
#include <acpi/acinterp.h>
#include <acpi/amlcode.h>
#include <acpi/acevents.h>
#include <acpi/acdispat.h>

#define _COMPONENT          ACPI_EXECUTER
ACPI_MODULE_NAME("exfldio")

/* Local prototypes */
static acpi_status
acpi_ex_field_datum_io(union acpi_operand_object *obj_desc,
		       u32 field_datum_byte_offset,
		       acpi_integer * value, u32 read_write);

static u8
acpi_ex_register_overflow(union acpi_operand_object *obj_desc,
			  acpi_integer value);

static acpi_status
acpi_ex_setup_region(union acpi_operand_object *obj_desc,
		     u32 field_datum_byte_offset);

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_setup_region
 *
 * PARAMETERS:  obj_desc                - Field to be read or written
 *              field_datum_byte_offset - Byte offset of this datum within the
 *                                        parent field
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Common processing for acpi_ex_extract_from_field and
 *              acpi_ex_insert_into_field. Initialize the Region if necessary and
 *              validate the request.
 *
 ******************************************************************************/

static acpi_status
acpi_ex_setup_region(union acpi_operand_object *obj_desc,
		     u32 field_datum_byte_offset)
{
	acpi_status status = AE_OK;
	union acpi_operand_object *rgn_desc;

	ACPI_FUNCTION_TRACE_U32(ex_setup_region, field_datum_byte_offset);

	rgn_desc = obj_desc->common_field.region_obj;

	/* We must have a valid region */

	if (ACPI_GET_OBJECT_TYPE(rgn_desc) != ACPI_TYPE_REGION) {
		ACPI_ERROR((AE_INFO, "Needed Region, found type %X (%s)",
			    ACPI_GET_OBJECT_TYPE(rgn_desc),
			    acpi_ut_get_object_type_name(rgn_desc)));

		return_ACPI_STATUS(AE_AML_OPERAND_TYPE);
	}

	/*
	 * If the Region Address and Length have not been previously evaluated,
	 * evaluate them now and save the results.
	 */
	if (!(rgn_desc->common.flags & AOPOBJ_DATA_VALID)) {
		status = acpi_ds_get_region_arguments(rgn_desc);
		if (ACPI_FAILURE(status)) {
			return_ACPI_STATUS(status);
		}
	}

	/* Exit if Address/Length have been disallowed by the host OS */

	if (rgn_desc->common.flags & AOPOBJ_INVALID) {
		return_ACPI_STATUS(AE_AML_ILLEGAL_ADDRESS);
	}

	/*
	 * Exit now for SMBus address space, it has a non-linear address space
	 * and the request cannot be directly validated
	 */
	if (rgn_desc->region.space_id == ACPI_ADR_SPACE_SMBUS) {

		/* SMBus has a non-linear address space */

		return_ACPI_STATUS(AE_OK);
	}
#ifdef ACPI_UNDER_DEVELOPMENT
	/*
	 * If the Field access is any_acc, we can now compute the optimal
	 * access (because we know know the length of the parent region)
	 */
	if (!(obj_desc->common.flags & AOPOBJ_DATA_VALID)) {
		if (ACPI_FAILURE(status)) {
			return_ACPI_STATUS(status);
		}
	}
#endif

	/*
	 * Validate the request.  The entire request from the byte offset for a
	 * length of one field datum (access width) must fit within the region.
	 * (Region length is specified in bytes)
	 */
	if (rgn_desc->region.length <
	    (obj_desc->common_field.base_byte_offset +
	     field_datum_byte_offset +
	     obj_desc->common_field.access_byte_width)) {
		if (acpi_gbl_enable_interpreter_slack) {
			/*
			 * Slack mode only:  We will go ahead and allow access to this
			 * field if it is within the region length rounded up to the next
			 * access width boundary.
			 */
			if (ACPI_ROUND_UP(rgn_desc->region.length,
					  obj_desc->common_field.
					  access_byte_width) >=
			    (obj_desc->common_field.base_byte_offset +
			     (acpi_native_uint) obj_desc->common_field.
			     access_byte_width + field_datum_byte_offset)) {
				return_ACPI_STATUS(AE_OK);
			}
		}

		if (rgn_desc->region.length <
		    obj_desc->common_field.access_byte_width) {
			/*
			 * This is the case where the access_type (acc_word, etc.) is wider
			 * than the region itself.  For example, a region of length one
			 * byte, and a field with Dword access specified.
			 */
			ACPI_ERROR((AE_INFO,
				    "Field [%4.4s] access width (%d bytes) too large for region [%4.4s] (length %X)",
				    acpi_ut_get_node_name(obj_desc->
							  common_field.node),
				    obj_desc->common_field.access_byte_width,
				    acpi_ut_get_node_name(rgn_desc->region.
							  node),
				    rgn_desc->region.length));
		}

		/*
		 * Offset rounded up to next multiple of field width
		 * exceeds region length, indicate an error
		 */
		ACPI_ERROR((AE_INFO,
			    "Field [%4.4s] Base+Offset+Width %X+%X+%X is beyond end of region [%4.4s] (length %X)",
			    acpi_ut_get_node_name(obj_desc->common_field.node),
			    obj_desc->common_field.base_byte_offset,
			    field_datum_byte_offset,
			    obj_desc->common_field.access_byte_width,
			    acpi_ut_get_node_name(rgn_desc->region.node),
			    rgn_desc->region.length));

		return_ACPI_STATUS(AE_AML_REGION_LIMIT);
	}

	return_ACPI_STATUS(AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_access_region
 *
 * PARAMETERS:  obj_desc                - Field to be read
 *              field_datum_byte_offset - Byte offset of this datum within the
 *                                        parent field
 *              Value                   - Where to store value (must at least
 *                                        the size of acpi_integer)
 *              Function                - Read or Write flag plus other region-
 *                                        dependent flags
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Read or Write a single field datum to an Operation Region.
 *
 ******************************************************************************/

acpi_status
acpi_ex_access_region(union acpi_operand_object *obj_desc,
		      u32 field_datum_byte_offset,
		      acpi_integer * value, u32 function)
{
	acpi_status status;
	union acpi_operand_object *rgn_desc;
	acpi_physical_address address;

	ACPI_FUNCTION_TRACE(ex_access_region);

	/*
	 * Ensure that the region operands are fully evaluated and verify
	 * the validity of the request
	 */
	status = acpi_ex_setup_region(obj_desc, field_datum_byte_offset);
	if (ACPI_FAILURE(status)) {
		return_ACPI_STATUS(status);
	}

	/*
	 * The physical address of this field datum is:
	 *
	 * 1) The base of the region, plus
	 * 2) The base offset of the field, plus
	 * 3) The current offset into the field
	 */
	rgn_desc = obj_desc->common_field.region_obj;
	address = rgn_desc->region.address +
	    obj_desc->common_field.base_byte_offset + field_datum_byte_offset;

	if ((function & ACPI_IO_MASK) == ACPI_READ) {
		ACPI_DEBUG_PRINT((ACPI_DB_BFIELD, "[READ]"));
	} else {
		ACPI_DEBUG_PRINT((ACPI_DB_BFIELD, "[WRITE]"));
	}

	ACPI_DEBUG_PRINT_RAW((ACPI_DB_BFIELD,
			      " Region [%s:%X], Width %X, ByteBase %X, Offset %X at %8.8X%8.8X\n",
			      acpi_ut_get_region_name(rgn_desc->region.
						      space_id),
			      rgn_desc->region.space_id,
			      obj_desc->common_field.access_byte_width,
			      obj_desc->common_field.base_byte_offset,
			      field_datum_byte_offset,
			      ACPI_FORMAT_UINT64(address)));

	/* Invoke the appropriate address_space/op_region handler */

	status = acpi_ev_address_space_dispatch(rgn_desc, function,
						address,
						ACPI_MUL_8(obj_desc->
							   common_field.
							   access_byte_width),
						value);

	if (ACPI_FAILURE(status)) {
		if (status == AE_NOT_IMPLEMENTED) {
			ACPI_ERROR((AE_INFO,
				    "Region %s(%X) not implemented",
				    acpi_ut_get_region_name(rgn_desc->region.
							    space_id),
				    rgn_desc->region.space_id));
		} else if (status == AE_NOT_EXIST) {
			ACPI_ERROR((AE_INFO,
				    "Region %s(%X) has no handler",
				    acpi_ut_get_region_name(rgn_desc->region.
							    space_id),
				    rgn_desc->region.space_id));
		}
	}

	return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_register_overflow
 *
 * PARAMETERS:  obj_desc                - Register(Field) to be written
 *              Value                   - Value to be stored
 *
 * RETURN:      TRUE if value overflows the field, FALSE otherwise
 *
 * DESCRIPTION: Check if a value is out of range of the field being written.
 *              Used to check if the values written to Index and Bank registers
 *              are out of range.  Normally, the value is simply truncated
 *              to fit the field, but this case is most likely a serious
 *              coding error in the ASL.
 *
 ******************************************************************************/

static u8
acpi_ex_register_overflow(union acpi_operand_object *obj_desc,
			  acpi_integer value)
{

	if (obj_desc->common_field.bit_length >= ACPI_INTEGER_BIT_SIZE) {
		/*
		 * The field is large enough to hold the maximum integer, so we can
		 * never overflow it.
		 */
		return (FALSE);
	}

	if (value >= ((acpi_integer) 1 << obj_desc->common_field.bit_length)) {
		/*
		 * The Value is larger than the maximum value that can fit into
		 * the register.
		 */
		return (TRUE);
	}

	/* The Value will fit into the field with no truncation */

	return (FALSE);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_field_datum_io
 *
 * PARAMETERS:  obj_desc                - Field to be read
 *              field_datum_byte_offset - Byte offset of this datum within the
 *                                        parent field
 *              Value                   - Where to store value (must be 64 bits)
 *              read_write              - Read or Write flag
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Read or Write a single datum of a field.  The field_type is
 *              demultiplexed here to handle the different types of fields
 *              (buffer_field, region_field, index_field, bank_field)
 *
 ******************************************************************************/

static acpi_status
acpi_ex_field_datum_io(union acpi_operand_object *obj_desc,
		       u32 field_datum_byte_offset,
		       acpi_integer * value, u32 read_write)
{
	acpi_status status;
	acpi_integer local_value;

	ACPI_FUNCTION_TRACE_U32(ex_field_datum_io, field_datum_byte_offset);

	if (read_write == ACPI_READ) {
		if (!value) {
			local_value = 0;

			/* To support reads without saving return value */
			value = &local_value;
		}

		/* Clear the entire return buffer first, [Very Important!] */

		*value = 0;
	}

	/*
	 * The four types of fields are:
	 *
	 * buffer_field - Read/write from/to a Buffer
	 * region_field - Read/write from/to a Operation Region.
	 * bank_field  - Write to a Bank Register, then read/write from/to an
	 *               operation_region
	 * index_field - Write to an Index Register, then read/write from/to a
	 *               Data Register
	 */
	switch (ACPI_GET_OBJECT_TYPE(obj_desc)) {
	case ACPI_TYPE_BUFFER_FIELD:
		/*
		 * If the buffer_field arguments have not been previously evaluated,
		 * evaluate them now and save the results.
		 */
		if (!(obj_desc->common.flags & AOPOBJ_DATA_VALID)) {
			status = acpi_ds_get_buffer_field_arguments(obj_desc);
			if (ACPI_FAILURE(status)) {
				return_ACPI_STATUS(status);
			}
		}

		if (read_write == ACPI_READ) {
			/*
			 * Copy the data from the source buffer.
			 * Length is the field width in bytes.
			 */
			ACPI_MEMCPY(value,
				    (obj_desc->buffer_field.buffer_obj)->buffer.
				    pointer +
				    obj_desc->buffer_field.base_byte_offset +
				    field_datum_byte_offset,
				    obj_desc->common_field.access_byte_width);
		} else {
			/*
			 * Copy the data to the target buffer.
			 * Length is the field width in bytes.
			 */
			ACPI_MEMCPY((obj_desc->buffer_field.buffer_obj)->buffer.
				    pointer +
				    obj_desc->buffer_field.base_byte_offset +
				    field_datum_byte_offset, value,
				    obj_desc->common_field.access_byte_width);
		}

		status = AE_OK;
		break;

	case ACPI_TYPE_LOCAL_BANK_FIELD:

		/*
		 * Ensure that the bank_value is not beyond the capacity of
		 * the register
		 */
		if (acpi_ex_register_overflow(obj_desc->bank_field.bank_obj,
					      (acpi_integer) obj_desc->
					      bank_field.value)) {
			return_ACPI_STATUS(AE_AML_REGISTER_LIMIT);
		}

		/*
		 * For bank_fields, we must write the bank_value to the bank_register
		 * (itself a region_field) before we can access the data.
		 */
		status =
		    acpi_ex_insert_into_field(obj_desc->bank_field.bank_obj,
					      &obj_desc->bank_field.value,
					      sizeof(obj_desc->bank_field.
						     value));
		if (ACPI_FAILURE(status)) {
			return_ACPI_STATUS(status);
		}

		/*
		 * Now that the Bank has been selected, fall through to the
		 * region_field case and write the datum to the Operation Region
		 */

		/*lint -fallthrough */

	case ACPI_TYPE_LOCAL_REGION_FIELD:
		/*
		 * For simple region_fields, we just directly access the owning
		 * Operation Region.
		 */
		status =
		    acpi_ex_access_region(obj_desc, field_datum_byte_offset,
					  value, read_write);
		break;

	case ACPI_TYPE_LOCAL_INDEX_FIELD:

		/*
		 * Ensure that the index_value is not beyond the capacity of
		 * the register
		 */
		if (acpi_ex_register_overflow(obj_desc->index_field.index_obj,
					      (acpi_integer) obj_desc->
					      index_field.value)) {
			return_ACPI_STATUS(AE_AML_REGISTER_LIMIT);
		}

		/* Write the index value to the index_register (itself a region_field) */

		field_datum_byte_offset += obj_desc->index_field.value;

		ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
				  "Write to Index Register: Value %8.8X\n",
				  field_datum_byte_offset));

		status =
		    acpi_ex_insert_into_field(obj_desc->index_field.index_obj,
					      &field_datum_byte_offset,
					      sizeof(field_datum_byte_offset));
		if (ACPI_FAILURE(status)) {
			return_ACPI_STATUS(status);
		}

		ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
				  "I/O to Data Register: ValuePtr %p\n",
				  value));

		if (read_write == ACPI_READ) {

			/* Read the datum from the data_register */

			status =
			    acpi_ex_extract_from_field(obj_desc->index_field.
						       data_obj, value,
						       sizeof(acpi_integer));
		} else {
			/* Write the datum to the data_register */

			status =
			    acpi_ex_insert_into_field(obj_desc->index_field.
						      data_obj, value,
						      sizeof(acpi_integer));
		}
		break;

	default:

		ACPI_ERROR((AE_INFO, "Wrong object type in field I/O %X",
			    ACPI_GET_OBJECT_TYPE(obj_desc)));
		status = AE_AML_INTERNAL;
		break;
	}

	if (ACPI_SUCCESS(status)) {
		if (read_write == ACPI_READ) {
			ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
					  "Value Read %8.8X%8.8X, Width %d\n",
					  ACPI_FORMAT_UINT64(*value),
					  obj_desc->common_field.
					  access_byte_width));
		} else {
			ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
					  "Value Written %8.8X%8.8X, Width %d\n",
					  ACPI_FORMAT_UINT64(*value),
					  obj_desc->common_field.
					  access_byte_width));
		}
	}

	return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_write_with_update_rule
 *
 * PARAMETERS:  obj_desc                - Field to be written
 *              Mask                    - bitmask within field datum
 *              field_value             - Value to write
 *              field_datum_byte_offset - Offset of datum within field
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Apply the field update rule to a field write
 *
 ******************************************************************************/

acpi_status
acpi_ex_write_with_update_rule(union acpi_operand_object *obj_desc,
			       acpi_integer mask,
			       acpi_integer field_value,
			       u32 field_datum_byte_offset)
{
	acpi_status status = AE_OK;
	acpi_integer merged_value;
	acpi_integer current_value;

	ACPI_FUNCTION_TRACE_U32(ex_write_with_update_rule, mask);

	/* Start with the new bits  */

	merged_value = field_value;

	/* If the mask is all ones, we don't need to worry about the update rule */

	if (mask != ACPI_INTEGER_MAX) {

		/* Decode the update rule */

		switch (obj_desc->common_field.
			field_flags & AML_FIELD_UPDATE_RULE_MASK) {
		case AML_FIELD_UPDATE_PRESERVE:
			/*
			 * Check if update rule needs to be applied (not if mask is all
			 * ones)  The left shift drops the bits we want to ignore.
			 */
			if ((~mask << (ACPI_MUL_8(sizeof(mask)) -
				       ACPI_MUL_8(obj_desc->common_field.
						  access_byte_width))) != 0) {
				/*
				 * Read the current contents of the byte/word/dword containing
				 * the field, and merge with the new field value.
				 */
				status =
				    acpi_ex_field_datum_io(obj_desc,
							   field_datum_byte_offset,
							   &current_value,
							   ACPI_READ);
				if (ACPI_FAILURE(status)) {
					return_ACPI_STATUS(status);
				}

				merged_value |= (current_value & ~mask);
			}
			break;

		case AML_FIELD_UPDATE_WRITE_AS_ONES:

			/* Set positions outside the field to all ones */

			merged_value |= ~mask;
			break;

		case AML_FIELD_UPDATE_WRITE_AS_ZEROS:

			/* Set positions outside the field to all zeros */

			merged_value &= mask;
			break;

		default:

			ACPI_ERROR((AE_INFO,
				    "Unknown UpdateRule value: %X",
				    (obj_desc->common_field.
				     field_flags &
				     AML_FIELD_UPDATE_RULE_MASK)));
			return_ACPI_STATUS(AE_AML_OPERAND_VALUE);
		}
	}

	ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
			  "Mask %8.8X%8.8X, DatumOffset %X, Width %X, Value %8.8X%8.8X, MergedValue %8.8X%8.8X\n",
			  ACPI_FORMAT_UINT64(mask),
			  field_datum_byte_offset,
			  obj_desc->common_field.access_byte_width,
			  ACPI_FORMAT_UINT64(field_value),
			  ACPI_FORMAT_UINT64(merged_value)));

	/* Write the merged value */

	status = acpi_ex_field_datum_io(obj_desc, field_datum_byte_offset,
					&merged_value, ACPI_WRITE);

	return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_extract_from_field
 *
 * PARAMETERS:  obj_desc            - Field to be read
 *              Buffer              - Where to store the field data
 *              buffer_length       - Length of Buffer
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Retrieve the current value of the given field
 *
 ******************************************************************************/

acpi_status
acpi_ex_extract_from_field(union acpi_operand_object *obj_desc,
			   void *buffer, u32 buffer_length)
{
	acpi_status status;
	acpi_integer raw_datum;
	acpi_integer merged_datum;
	u32 field_offset = 0;
	u32 buffer_offset = 0;
	u32 buffer_tail_bits;
	u32 datum_count;
	u32 field_datum_count;
	u32 i;

	ACPI_FUNCTION_TRACE(ex_extract_from_field);

	/* Validate target buffer and clear it */

	if (buffer_length <
	    ACPI_ROUND_BITS_UP_TO_BYTES(obj_desc->common_field.bit_length)) {
		ACPI_ERROR((AE_INFO,
			    "Field size %X (bits) is too large for buffer (%X)",
			    obj_desc->common_field.bit_length, buffer_length));

		return_ACPI_STATUS(AE_BUFFER_OVERFLOW);
	}
	ACPI_MEMSET(buffer, 0, buffer_length);

	/* Compute the number of datums (access width data items) */

	datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length,
				       obj_desc->common_field.access_bit_width);
	field_datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length +
					     obj_desc->common_field.
					     start_field_bit_offset,
					     obj_desc->common_field.
					     access_bit_width);

	/* Priming read from the field */

	status =
	    acpi_ex_field_datum_io(obj_desc, field_offset, &raw_datum,
				   ACPI_READ);
	if (ACPI_FAILURE(status)) {
		return_ACPI_STATUS(status);
	}
	merged_datum =
	    raw_datum >> obj_desc->common_field.start_field_bit_offset;

	/* Read the rest of the field */

	for (i = 1; i < field_datum_count; i++) {

		/* Get next input datum from the field */

		field_offset += obj_desc->common_field.access_byte_width;
		status = acpi_ex_field_datum_io(obj_desc, field_offset,
						&raw_datum, ACPI_READ);
		if (ACPI_FAILURE(status)) {
			return_ACPI_STATUS(status);
		}

		/*
		 * Merge with previous datum if necessary.
		 *
		 * Note: Before the shift, check if the shift value will be larger than
		 * the integer size. If so, there is no need to perform the operation.
		 * This avoids the differences in behavior between different compilers
		 * concerning shift values larger than the target data width.
		 */
		if ((obj_desc->common_field.access_bit_width -
		     obj_desc->common_field.start_field_bit_offset) <
		    ACPI_INTEGER_BIT_SIZE) {
			merged_datum |=
			    raw_datum << (obj_desc->common_field.
					  access_bit_width -
					  obj_desc->common_field.
					  start_field_bit_offset);
		}

		if (i == datum_count) {
			break;
		}

		/* Write merged datum to target buffer */

		ACPI_MEMCPY(((char *)buffer) + buffer_offset, &merged_datum,
			    ACPI_MIN(obj_desc->common_field.access_byte_width,
				     buffer_length - buffer_offset));

		buffer_offset += obj_desc->common_field.access_byte_width;
		merged_datum =
		    raw_datum >> obj_desc->common_field.start_field_bit_offset;
	}

	/* Mask off any extra bits in the last datum */

	buffer_tail_bits = obj_desc->common_field.bit_length %
	    obj_desc->common_field.access_bit_width;
	if (buffer_tail_bits) {
		merged_datum &= ACPI_MASK_BITS_ABOVE(buffer_tail_bits);
	}

	/* Write the last datum to the buffer */

	ACPI_MEMCPY(((char *)buffer) + buffer_offset, &merged_datum,
		    ACPI_MIN(obj_desc->common_field.access_byte_width,
			     buffer_length - buffer_offset));

	return_ACPI_STATUS(AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_insert_into_field
 *
 * PARAMETERS:  obj_desc            - Field to be written
 *              Buffer              - Data to be written
 *              buffer_length       - Length of Buffer
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Store the Buffer contents into the given field
 *
 ******************************************************************************/

acpi_status
acpi_ex_insert_into_field(union acpi_operand_object *obj_desc,
			  void *buffer, u32 buffer_length)
{
	acpi_status status;
	acpi_integer mask;
	acpi_integer width_mask;
	acpi_integer merged_datum;
	acpi_integer raw_datum = 0;
	u32 field_offset = 0;
	u32 buffer_offset = 0;
	u32 buffer_tail_bits;
	u32 datum_count;
	u32 field_datum_count;
	u32 i;

	ACPI_FUNCTION_TRACE(ex_insert_into_field);

	/* Validate input buffer */

	if (buffer_length <
	    ACPI_ROUND_BITS_UP_TO_BYTES(obj_desc->common_field.bit_length)) {
		ACPI_ERROR((AE_INFO,
			    "Field size %X (bits) is too large for buffer (%X)",
			    obj_desc->common_field.bit_length, buffer_length));

		return_ACPI_STATUS(AE_BUFFER_OVERFLOW);
	}

	/*
	 * Create the bitmasks used for bit insertion.
	 * Note: This if/else is used to bypass compiler differences with the
	 * shift operator
	 */
	if (obj_desc->common_field.access_bit_width == ACPI_INTEGER_BIT_SIZE) {
		width_mask = ACPI_INTEGER_MAX;
	} else {
		width_mask =
		    ACPI_MASK_BITS_ABOVE(obj_desc->common_field.
					 access_bit_width);
	}

	mask = width_mask &
	    ACPI_MASK_BITS_BELOW(obj_desc->common_field.start_field_bit_offset);

	/* Compute the number of datums (access width data items) */

	datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length,
				       obj_desc->common_field.access_bit_width);

	field_datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length +
					     obj_desc->common_field.
					     start_field_bit_offset,
					     obj_desc->common_field.
					     access_bit_width);

	/* Get initial Datum from the input buffer */

	ACPI_MEMCPY(&raw_datum, buffer,
		    ACPI_MIN(obj_desc->common_field.access_byte_width,
			     buffer_length - buffer_offset));

	merged_datum =
	    raw_datum << obj_desc->common_field.start_field_bit_offset;

	/* Write the entire field */

	for (i = 1; i < field_datum_count; i++) {

		/* Write merged datum to the target field */

		merged_datum &= mask;
		status = acpi_ex_write_with_update_rule(obj_desc, mask,
							merged_datum,
							field_offset);
		if (ACPI_FAILURE(status)) {
			return_ACPI_STATUS(status);
		}

		field_offset += obj_desc->common_field.access_byte_width;

		/*
		 * Start new output datum by merging with previous input datum
		 * if necessary.
		 *
		 * Note: Before the shift, check if the shift value will be larger than
		 * the integer size. If so, there is no need to perform the operation.
		 * This avoids the differences in behavior between different compilers
		 * concerning shift values larger than the target data width.
		 */
		if ((obj_desc->common_field.access_bit_width -
		     obj_desc->common_field.start_field_bit_offset) <
		    ACPI_INTEGER_BIT_SIZE) {
			merged_datum =
			    raw_datum >> (obj_desc->common_field.
					  access_bit_width -
					  obj_desc->common_field.
					  start_field_bit_offset);
		} else {
			merged_datum = 0;
		}

		mask = width_mask;

		if (i == datum_count) {
			break;
		}

		/* Get the next input datum from the buffer */

		buffer_offset += obj_desc->common_field.access_byte_width;
		ACPI_MEMCPY(&raw_datum, ((char *)buffer) + buffer_offset,
			    ACPI_MIN(obj_desc->common_field.access_byte_width,
				     buffer_length - buffer_offset));
		merged_datum |=
		    raw_datum << obj_desc->common_field.start_field_bit_offset;
	}

	/* Mask off any extra bits in the last datum */

	buffer_tail_bits = (obj_desc->common_field.bit_length +
			    obj_desc->common_field.start_field_bit_offset) %
	    obj_desc->common_field.access_bit_width;
	if (buffer_tail_bits) {
		mask &= ACPI_MASK_BITS_ABOVE(buffer_tail_bits);
	}

	/* Write the last datum to the field */

	merged_datum &= mask;
	status = acpi_ex_write_with_update_rule(obj_desc,
						mask, merged_datum,
						field_offset);

	return_ACPI_STATUS(status);
}