xref: /openbmc/linux/drivers/acpi/acpica/dsopcode.c (revision f220d3eb)
1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
2 /******************************************************************************
3  *
4  * Module Name: dsopcode - Dispatcher support for regions and fields
5  *
6  * Copyright (C) 2000 - 2018, Intel Corp.
7  *
8  *****************************************************************************/
9 
10 #include <acpi/acpi.h>
11 #include "accommon.h"
12 #include "acparser.h"
13 #include "amlcode.h"
14 #include "acdispat.h"
15 #include "acinterp.h"
16 #include "acnamesp.h"
17 #include "acevents.h"
18 #include "actables.h"
19 
20 #define _COMPONENT          ACPI_DISPATCHER
21 ACPI_MODULE_NAME("dsopcode")
22 
23 /* Local prototypes */
24 static acpi_status
25 acpi_ds_init_buffer_field(u16 aml_opcode,
26 			  union acpi_operand_object *obj_desc,
27 			  union acpi_operand_object *buffer_desc,
28 			  union acpi_operand_object *offset_desc,
29 			  union acpi_operand_object *length_desc,
30 			  union acpi_operand_object *result_desc);
31 
32 /*******************************************************************************
33  *
34  * FUNCTION:    acpi_ds_initialize_region
35  *
36  * PARAMETERS:  obj_handle      - Region namespace node
37  *
38  * RETURN:      Status
39  *
40  * DESCRIPTION: Front end to ev_initialize_region
41  *
42  ******************************************************************************/
43 
44 acpi_status acpi_ds_initialize_region(acpi_handle obj_handle)
45 {
46 	union acpi_operand_object *obj_desc;
47 	acpi_status status;
48 
49 	obj_desc = acpi_ns_get_attached_object(obj_handle);
50 
51 	/* Namespace is NOT locked */
52 
53 	status = acpi_ev_initialize_region(obj_desc);
54 	return (status);
55 }
56 
57 /*******************************************************************************
58  *
59  * FUNCTION:    acpi_ds_init_buffer_field
60  *
61  * PARAMETERS:  aml_opcode      - create_xxx_field
62  *              obj_desc        - buffer_field object
63  *              buffer_desc     - Host Buffer
64  *              offset_desc     - Offset into buffer
65  *              length_desc     - Length of field (CREATE_FIELD_OP only)
66  *              result_desc     - Where to store the result
67  *
68  * RETURN:      Status
69  *
70  * DESCRIPTION: Perform actual initialization of a buffer field
71  *
72  ******************************************************************************/
73 
74 static acpi_status
75 acpi_ds_init_buffer_field(u16 aml_opcode,
76 			  union acpi_operand_object *obj_desc,
77 			  union acpi_operand_object *buffer_desc,
78 			  union acpi_operand_object *offset_desc,
79 			  union acpi_operand_object *length_desc,
80 			  union acpi_operand_object *result_desc)
81 {
82 	u32 offset;
83 	u32 bit_offset;
84 	u32 bit_count;
85 	u8 field_flags;
86 	acpi_status status;
87 
88 	ACPI_FUNCTION_TRACE_PTR(ds_init_buffer_field, obj_desc);
89 
90 	/* Host object must be a Buffer */
91 
92 	if (buffer_desc->common.type != ACPI_TYPE_BUFFER) {
93 		ACPI_ERROR((AE_INFO,
94 			    "Target of Create Field is not a Buffer object - %s",
95 			    acpi_ut_get_object_type_name(buffer_desc)));
96 
97 		status = AE_AML_OPERAND_TYPE;
98 		goto cleanup;
99 	}
100 
101 	/*
102 	 * The last parameter to all of these opcodes (result_desc) started
103 	 * out as a name_string, and should therefore now be a NS node
104 	 * after resolution in acpi_ex_resolve_operands().
105 	 */
106 	if (ACPI_GET_DESCRIPTOR_TYPE(result_desc) != ACPI_DESC_TYPE_NAMED) {
107 		ACPI_ERROR((AE_INFO,
108 			    "(%s) destination not a NS Node [%s]",
109 			    acpi_ps_get_opcode_name(aml_opcode),
110 			    acpi_ut_get_descriptor_name(result_desc)));
111 
112 		status = AE_AML_OPERAND_TYPE;
113 		goto cleanup;
114 	}
115 
116 	offset = (u32) offset_desc->integer.value;
117 
118 	/*
119 	 * Setup the Bit offsets and counts, according to the opcode
120 	 */
121 	switch (aml_opcode) {
122 	case AML_CREATE_FIELD_OP:
123 
124 		/* Offset is in bits, count is in bits */
125 
126 		field_flags = AML_FIELD_ACCESS_BYTE;
127 		bit_offset = offset;
128 		bit_count = (u32) length_desc->integer.value;
129 
130 		/* Must have a valid (>0) bit count */
131 
132 		if (bit_count == 0) {
133 			ACPI_ERROR((AE_INFO,
134 				    "Attempt to CreateField of length zero"));
135 			status = AE_AML_OPERAND_VALUE;
136 			goto cleanup;
137 		}
138 		break;
139 
140 	case AML_CREATE_BIT_FIELD_OP:
141 
142 		/* Offset is in bits, Field is one bit */
143 
144 		bit_offset = offset;
145 		bit_count = 1;
146 		field_flags = AML_FIELD_ACCESS_BYTE;
147 		break;
148 
149 	case AML_CREATE_BYTE_FIELD_OP:
150 
151 		/* Offset is in bytes, field is one byte */
152 
153 		bit_offset = 8 * offset;
154 		bit_count = 8;
155 		field_flags = AML_FIELD_ACCESS_BYTE;
156 		break;
157 
158 	case AML_CREATE_WORD_FIELD_OP:
159 
160 		/* Offset is in bytes, field is one word */
161 
162 		bit_offset = 8 * offset;
163 		bit_count = 16;
164 		field_flags = AML_FIELD_ACCESS_WORD;
165 		break;
166 
167 	case AML_CREATE_DWORD_FIELD_OP:
168 
169 		/* Offset is in bytes, field is one dword */
170 
171 		bit_offset = 8 * offset;
172 		bit_count = 32;
173 		field_flags = AML_FIELD_ACCESS_DWORD;
174 		break;
175 
176 	case AML_CREATE_QWORD_FIELD_OP:
177 
178 		/* Offset is in bytes, field is one qword */
179 
180 		bit_offset = 8 * offset;
181 		bit_count = 64;
182 		field_flags = AML_FIELD_ACCESS_QWORD;
183 		break;
184 
185 	default:
186 
187 		ACPI_ERROR((AE_INFO,
188 			    "Unknown field creation opcode 0x%02X",
189 			    aml_opcode));
190 		status = AE_AML_BAD_OPCODE;
191 		goto cleanup;
192 	}
193 
194 	/* Entire field must fit within the current length of the buffer */
195 
196 	if ((bit_offset + bit_count) > (8 * (u32)buffer_desc->buffer.length)) {
197 		ACPI_ERROR((AE_INFO,
198 			    "Field [%4.4s] at bit offset/length %u/%u "
199 			    "exceeds size of target Buffer (%u bits)",
200 			    acpi_ut_get_node_name(result_desc), bit_offset,
201 			    bit_count, 8 * (u32)buffer_desc->buffer.length));
202 		status = AE_AML_BUFFER_LIMIT;
203 		goto cleanup;
204 	}
205 
206 	/*
207 	 * Initialize areas of the field object that are common to all fields
208 	 * For field_flags, use LOCK_RULE = 0 (NO_LOCK),
209 	 * UPDATE_RULE = 0 (UPDATE_PRESERVE)
210 	 */
211 	status =
212 	    acpi_ex_prep_common_field_object(obj_desc, field_flags, 0,
213 					     bit_offset, bit_count);
214 	if (ACPI_FAILURE(status)) {
215 		goto cleanup;
216 	}
217 
218 	obj_desc->buffer_field.buffer_obj = buffer_desc;
219 
220 	/* Reference count for buffer_desc inherits obj_desc count */
221 
222 	buffer_desc->common.reference_count = (u16)
223 	    (buffer_desc->common.reference_count +
224 	     obj_desc->common.reference_count);
225 
226 cleanup:
227 
228 	/* Always delete the operands */
229 
230 	acpi_ut_remove_reference(offset_desc);
231 	acpi_ut_remove_reference(buffer_desc);
232 
233 	if (aml_opcode == AML_CREATE_FIELD_OP) {
234 		acpi_ut_remove_reference(length_desc);
235 	}
236 
237 	/* On failure, delete the result descriptor */
238 
239 	if (ACPI_FAILURE(status)) {
240 		acpi_ut_remove_reference(result_desc);	/* Result descriptor */
241 	} else {
242 		/* Now the address and length are valid for this buffer_field */
243 
244 		obj_desc->buffer_field.flags |= AOPOBJ_DATA_VALID;
245 	}
246 
247 	return_ACPI_STATUS(status);
248 }
249 
250 /*******************************************************************************
251  *
252  * FUNCTION:    acpi_ds_eval_buffer_field_operands
253  *
254  * PARAMETERS:  walk_state      - Current walk
255  *              op              - A valid buffer_field Op object
256  *
257  * RETURN:      Status
258  *
259  * DESCRIPTION: Get buffer_field Buffer and Index
260  *              Called from acpi_ds_exec_end_op during buffer_field parse tree walk
261  *
262  ******************************************************************************/
263 
264 acpi_status
265 acpi_ds_eval_buffer_field_operands(struct acpi_walk_state *walk_state,
266 				   union acpi_parse_object *op)
267 {
268 	acpi_status status;
269 	union acpi_operand_object *obj_desc;
270 	struct acpi_namespace_node *node;
271 	union acpi_parse_object *next_op;
272 
273 	ACPI_FUNCTION_TRACE_PTR(ds_eval_buffer_field_operands, op);
274 
275 	/*
276 	 * This is where we evaluate the address and length fields of the
277 	 * create_xxx_field declaration
278 	 */
279 	node = op->common.node;
280 
281 	/* next_op points to the op that holds the Buffer */
282 
283 	next_op = op->common.value.arg;
284 
285 	/* Evaluate/create the address and length operands */
286 
287 	status = acpi_ds_create_operands(walk_state, next_op);
288 	if (ACPI_FAILURE(status)) {
289 		return_ACPI_STATUS(status);
290 	}
291 
292 	obj_desc = acpi_ns_get_attached_object(node);
293 	if (!obj_desc) {
294 		return_ACPI_STATUS(AE_NOT_EXIST);
295 	}
296 
297 	/* Resolve the operands */
298 
299 	status =
300 	    acpi_ex_resolve_operands(op->common.aml_opcode, ACPI_WALK_OPERANDS,
301 				     walk_state);
302 	if (ACPI_FAILURE(status)) {
303 		ACPI_ERROR((AE_INFO, "(%s) bad operand(s), status 0x%X",
304 			    acpi_ps_get_opcode_name(op->common.aml_opcode),
305 			    status));
306 
307 		return_ACPI_STATUS(status);
308 	}
309 
310 	/* Initialize the Buffer Field */
311 
312 	if (op->common.aml_opcode == AML_CREATE_FIELD_OP) {
313 
314 		/* NOTE: Slightly different operands for this opcode */
315 
316 		status =
317 		    acpi_ds_init_buffer_field(op->common.aml_opcode, obj_desc,
318 					      walk_state->operands[0],
319 					      walk_state->operands[1],
320 					      walk_state->operands[2],
321 					      walk_state->operands[3]);
322 	} else {
323 		/* All other, create_xxx_field opcodes */
324 
325 		status =
326 		    acpi_ds_init_buffer_field(op->common.aml_opcode, obj_desc,
327 					      walk_state->operands[0],
328 					      walk_state->operands[1], NULL,
329 					      walk_state->operands[2]);
330 	}
331 
332 	return_ACPI_STATUS(status);
333 }
334 
335 /*******************************************************************************
336  *
337  * FUNCTION:    acpi_ds_eval_region_operands
338  *
339  * PARAMETERS:  walk_state      - Current walk
340  *              op              - A valid region Op object
341  *
342  * RETURN:      Status
343  *
344  * DESCRIPTION: Get region address and length
345  *              Called from acpi_ds_exec_end_op during op_region parse tree walk
346  *
347  ******************************************************************************/
348 
349 acpi_status
350 acpi_ds_eval_region_operands(struct acpi_walk_state *walk_state,
351 			     union acpi_parse_object *op)
352 {
353 	acpi_status status;
354 	union acpi_operand_object *obj_desc;
355 	union acpi_operand_object *operand_desc;
356 	struct acpi_namespace_node *node;
357 	union acpi_parse_object *next_op;
358 
359 	ACPI_FUNCTION_TRACE_PTR(ds_eval_region_operands, op);
360 
361 	/*
362 	 * This is where we evaluate the address and length fields of the
363 	 * op_region declaration
364 	 */
365 	node = op->common.node;
366 
367 	/* next_op points to the op that holds the space_ID */
368 
369 	next_op = op->common.value.arg;
370 
371 	/* next_op points to address op */
372 
373 	next_op = next_op->common.next;
374 
375 	/* Evaluate/create the address and length operands */
376 
377 	status = acpi_ds_create_operands(walk_state, next_op);
378 	if (ACPI_FAILURE(status)) {
379 		return_ACPI_STATUS(status);
380 	}
381 
382 	/* Resolve the length and address operands to numbers */
383 
384 	status =
385 	    acpi_ex_resolve_operands(op->common.aml_opcode, ACPI_WALK_OPERANDS,
386 				     walk_state);
387 	if (ACPI_FAILURE(status)) {
388 		return_ACPI_STATUS(status);
389 	}
390 
391 	obj_desc = acpi_ns_get_attached_object(node);
392 	if (!obj_desc) {
393 		return_ACPI_STATUS(AE_NOT_EXIST);
394 	}
395 
396 	/*
397 	 * Get the length operand and save it
398 	 * (at Top of stack)
399 	 */
400 	operand_desc = walk_state->operands[walk_state->num_operands - 1];
401 
402 	obj_desc->region.length = (u32) operand_desc->integer.value;
403 	acpi_ut_remove_reference(operand_desc);
404 
405 	/*
406 	 * Get the address and save it
407 	 * (at top of stack - 1)
408 	 */
409 	operand_desc = walk_state->operands[walk_state->num_operands - 2];
410 
411 	obj_desc->region.address = (acpi_physical_address)
412 	    operand_desc->integer.value;
413 	acpi_ut_remove_reference(operand_desc);
414 
415 	ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "RgnObj %p Addr %8.8X%8.8X Len %X\n",
416 			  obj_desc,
417 			  ACPI_FORMAT_UINT64(obj_desc->region.address),
418 			  obj_desc->region.length));
419 
420 	/* Now the address and length are valid for this opregion */
421 
422 	obj_desc->region.flags |= AOPOBJ_DATA_VALID;
423 	return_ACPI_STATUS(status);
424 }
425 
426 /*******************************************************************************
427  *
428  * FUNCTION:    acpi_ds_eval_table_region_operands
429  *
430  * PARAMETERS:  walk_state      - Current walk
431  *              op              - A valid region Op object
432  *
433  * RETURN:      Status
434  *
435  * DESCRIPTION: Get region address and length.
436  *              Called from acpi_ds_exec_end_op during data_table_region parse
437  *              tree walk.
438  *
439  ******************************************************************************/
440 
441 acpi_status
442 acpi_ds_eval_table_region_operands(struct acpi_walk_state *walk_state,
443 				   union acpi_parse_object *op)
444 {
445 	acpi_status status;
446 	union acpi_operand_object *obj_desc;
447 	union acpi_operand_object **operand;
448 	struct acpi_namespace_node *node;
449 	union acpi_parse_object *next_op;
450 	struct acpi_table_header *table;
451 	u32 table_index;
452 
453 	ACPI_FUNCTION_TRACE_PTR(ds_eval_table_region_operands, op);
454 
455 	/*
456 	 * This is where we evaluate the Signature string, oem_id string,
457 	 * and oem_table_id string of the Data Table Region declaration
458 	 */
459 	node = op->common.node;
460 
461 	/* next_op points to Signature string op */
462 
463 	next_op = op->common.value.arg;
464 
465 	/*
466 	 * Evaluate/create the Signature string, oem_id string,
467 	 * and oem_table_id string operands
468 	 */
469 	status = acpi_ds_create_operands(walk_state, next_op);
470 	if (ACPI_FAILURE(status)) {
471 		return_ACPI_STATUS(status);
472 	}
473 
474 	operand = &walk_state->operands[0];
475 
476 	/*
477 	 * Resolve the Signature string, oem_id string,
478 	 * and oem_table_id string operands
479 	 */
480 	status =
481 	    acpi_ex_resolve_operands(op->common.aml_opcode, ACPI_WALK_OPERANDS,
482 				     walk_state);
483 	if (ACPI_FAILURE(status)) {
484 		goto cleanup;
485 	}
486 
487 	/* Find the ACPI table */
488 
489 	status = acpi_tb_find_table(operand[0]->string.pointer,
490 				    operand[1]->string.pointer,
491 				    operand[2]->string.pointer, &table_index);
492 	if (ACPI_FAILURE(status)) {
493 		if (status == AE_NOT_FOUND) {
494 			ACPI_ERROR((AE_INFO,
495 				    "ACPI Table [%4.4s] OEM:(%s, %s) not found in RSDT/XSDT",
496 				    operand[0]->string.pointer,
497 				    operand[1]->string.pointer,
498 				    operand[2]->string.pointer));
499 		}
500 		goto cleanup;
501 	}
502 
503 	status = acpi_get_table_by_index(table_index, &table);
504 	if (ACPI_FAILURE(status)) {
505 		goto cleanup;
506 	}
507 
508 	obj_desc = acpi_ns_get_attached_object(node);
509 	if (!obj_desc) {
510 		status = AE_NOT_EXIST;
511 		goto cleanup;
512 	}
513 
514 	obj_desc->region.address = ACPI_PTR_TO_PHYSADDR(table);
515 	obj_desc->region.length = table->length;
516 
517 	ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "RgnObj %p Addr %8.8X%8.8X Len %X\n",
518 			  obj_desc,
519 			  ACPI_FORMAT_UINT64(obj_desc->region.address),
520 			  obj_desc->region.length));
521 
522 	/* Now the address and length are valid for this opregion */
523 
524 	obj_desc->region.flags |= AOPOBJ_DATA_VALID;
525 
526 cleanup:
527 	acpi_ut_remove_reference(operand[0]);
528 	acpi_ut_remove_reference(operand[1]);
529 	acpi_ut_remove_reference(operand[2]);
530 
531 	return_ACPI_STATUS(status);
532 }
533 
534 /*******************************************************************************
535  *
536  * FUNCTION:    acpi_ds_eval_data_object_operands
537  *
538  * PARAMETERS:  walk_state      - Current walk
539  *              op              - A valid data_object Op object
540  *              obj_desc        - data_object
541  *
542  * RETURN:      Status
543  *
544  * DESCRIPTION: Get the operands and complete the following data object types:
545  *              Buffer, Package.
546  *
547  ******************************************************************************/
548 
549 acpi_status
550 acpi_ds_eval_data_object_operands(struct acpi_walk_state *walk_state,
551 				  union acpi_parse_object *op,
552 				  union acpi_operand_object *obj_desc)
553 {
554 	acpi_status status;
555 	union acpi_operand_object *arg_desc;
556 	u32 length;
557 
558 	ACPI_FUNCTION_TRACE(ds_eval_data_object_operands);
559 
560 	/* The first operand (for all of these data objects) is the length */
561 
562 	/*
563 	 * Set proper index into operand stack for acpi_ds_obj_stack_push
564 	 * invoked inside acpi_ds_create_operand.
565 	 */
566 	walk_state->operand_index = walk_state->num_operands;
567 
568 	/* Ignore if child is not valid */
569 
570 	if (!op->common.value.arg) {
571 		ACPI_ERROR((AE_INFO,
572 			    "Missing child while evaluating opcode %4.4X, Op %p",
573 			    op->common.aml_opcode, op));
574 		return_ACPI_STATUS(AE_OK);
575 	}
576 
577 	status = acpi_ds_create_operand(walk_state, op->common.value.arg, 1);
578 	if (ACPI_FAILURE(status)) {
579 		return_ACPI_STATUS(status);
580 	}
581 
582 	status = acpi_ex_resolve_operands(walk_state->opcode,
583 					  &(walk_state->
584 					    operands[walk_state->num_operands -
585 						     1]), walk_state);
586 	if (ACPI_FAILURE(status)) {
587 		return_ACPI_STATUS(status);
588 	}
589 
590 	/* Extract length operand */
591 
592 	arg_desc = walk_state->operands[walk_state->num_operands - 1];
593 	length = (u32) arg_desc->integer.value;
594 
595 	/* Cleanup for length operand */
596 
597 	status = acpi_ds_obj_stack_pop(1, walk_state);
598 	if (ACPI_FAILURE(status)) {
599 		return_ACPI_STATUS(status);
600 	}
601 
602 	acpi_ut_remove_reference(arg_desc);
603 
604 	/*
605 	 * Create the actual data object
606 	 */
607 	switch (op->common.aml_opcode) {
608 	case AML_BUFFER_OP:
609 
610 		status =
611 		    acpi_ds_build_internal_buffer_obj(walk_state, op, length,
612 						      &obj_desc);
613 		break;
614 
615 	case AML_PACKAGE_OP:
616 	case AML_VARIABLE_PACKAGE_OP:
617 
618 		status =
619 		    acpi_ds_build_internal_package_obj(walk_state, op, length,
620 						       &obj_desc);
621 		break;
622 
623 	default:
624 
625 		return_ACPI_STATUS(AE_AML_BAD_OPCODE);
626 	}
627 
628 	if (ACPI_SUCCESS(status)) {
629 		/*
630 		 * Return the object in the walk_state, unless the parent is a package -
631 		 * in this case, the return object will be stored in the parse tree
632 		 * for the package.
633 		 */
634 		if ((!op->common.parent) ||
635 		    ((op->common.parent->common.aml_opcode != AML_PACKAGE_OP) &&
636 		     (op->common.parent->common.aml_opcode !=
637 		      AML_VARIABLE_PACKAGE_OP)
638 		     && (op->common.parent->common.aml_opcode !=
639 			 AML_NAME_OP))) {
640 			walk_state->result_obj = obj_desc;
641 		}
642 	}
643 
644 	return_ACPI_STATUS(status);
645 }
646 
647 /*******************************************************************************
648  *
649  * FUNCTION:    acpi_ds_eval_bank_field_operands
650  *
651  * PARAMETERS:  walk_state      - Current walk
652  *              op              - A valid bank_field Op object
653  *
654  * RETURN:      Status
655  *
656  * DESCRIPTION: Get bank_field bank_value
657  *              Called from acpi_ds_exec_end_op during bank_field parse tree walk
658  *
659  ******************************************************************************/
660 
661 acpi_status
662 acpi_ds_eval_bank_field_operands(struct acpi_walk_state *walk_state,
663 				 union acpi_parse_object *op)
664 {
665 	acpi_status status;
666 	union acpi_operand_object *obj_desc;
667 	union acpi_operand_object *operand_desc;
668 	struct acpi_namespace_node *node;
669 	union acpi_parse_object *next_op;
670 	union acpi_parse_object *arg;
671 
672 	ACPI_FUNCTION_TRACE_PTR(ds_eval_bank_field_operands, op);
673 
674 	/*
675 	 * This is where we evaluate the bank_value field of the
676 	 * bank_field declaration
677 	 */
678 
679 	/* next_op points to the op that holds the Region */
680 
681 	next_op = op->common.value.arg;
682 
683 	/* next_op points to the op that holds the Bank Register */
684 
685 	next_op = next_op->common.next;
686 
687 	/* next_op points to the op that holds the Bank Value */
688 
689 	next_op = next_op->common.next;
690 
691 	/*
692 	 * Set proper index into operand stack for acpi_ds_obj_stack_push
693 	 * invoked inside acpi_ds_create_operand.
694 	 *
695 	 * We use walk_state->Operands[0] to store the evaluated bank_value
696 	 */
697 	walk_state->operand_index = 0;
698 
699 	status = acpi_ds_create_operand(walk_state, next_op, 0);
700 	if (ACPI_FAILURE(status)) {
701 		return_ACPI_STATUS(status);
702 	}
703 
704 	status = acpi_ex_resolve_to_value(&walk_state->operands[0], walk_state);
705 	if (ACPI_FAILURE(status)) {
706 		return_ACPI_STATUS(status);
707 	}
708 
709 	ACPI_DUMP_OPERANDS(ACPI_WALK_OPERANDS,
710 			   acpi_ps_get_opcode_name(op->common.aml_opcode), 1);
711 	/*
712 	 * Get the bank_value operand and save it
713 	 * (at Top of stack)
714 	 */
715 	operand_desc = walk_state->operands[0];
716 
717 	/* Arg points to the start Bank Field */
718 
719 	arg = acpi_ps_get_arg(op, 4);
720 	while (arg) {
721 
722 		/* Ignore OFFSET and ACCESSAS terms here */
723 
724 		if (arg->common.aml_opcode == AML_INT_NAMEDFIELD_OP) {
725 			node = arg->common.node;
726 
727 			obj_desc = acpi_ns_get_attached_object(node);
728 			if (!obj_desc) {
729 				return_ACPI_STATUS(AE_NOT_EXIST);
730 			}
731 
732 			obj_desc->bank_field.value =
733 			    (u32) operand_desc->integer.value;
734 		}
735 
736 		/* Move to next field in the list */
737 
738 		arg = arg->common.next;
739 	}
740 
741 	acpi_ut_remove_reference(operand_desc);
742 	return_ACPI_STATUS(status);
743 }
744