xref: /openbmc/linux/drivers/acpi/acpica/psargs.c (revision 1587db11)
1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
2 /******************************************************************************
3  *
4  * Module Name: psargs - Parse AML opcode arguments
5  *
6  * Copyright (C) 2000 - 2023, Intel Corp.
7  *
8  *****************************************************************************/
9 
10 #include <acpi/acpi.h>
11 #include "accommon.h"
12 #include "acparser.h"
13 #include "amlcode.h"
14 #include "acnamesp.h"
15 #include "acdispat.h"
16 #include "acconvert.h"
17 
18 #define _COMPONENT          ACPI_PARSER
19 ACPI_MODULE_NAME("psargs")
20 
21 /* Local prototypes */
22 static u32
23 acpi_ps_get_next_package_length(struct acpi_parse_state *parser_state);
24 
25 static union acpi_parse_object *acpi_ps_get_next_field(struct acpi_parse_state
26 						       *parser_state);
27 
28 static void acpi_ps_free_field_list(union acpi_parse_object *start);
29 
30 /*******************************************************************************
31  *
32  * FUNCTION:    acpi_ps_get_next_package_length
33  *
34  * PARAMETERS:  parser_state        - Current parser state object
35  *
36  * RETURN:      Decoded package length. On completion, the AML pointer points
37  *              past the length byte or bytes.
38  *
39  * DESCRIPTION: Decode and return a package length field.
40  *              Note: Largest package length is 28 bits, from ACPI specification
41  *
42  ******************************************************************************/
43 
44 static u32
45 acpi_ps_get_next_package_length(struct acpi_parse_state *parser_state)
46 {
47 	u8 *aml = parser_state->aml;
48 	u32 package_length = 0;
49 	u32 byte_count;
50 	u8 byte_zero_mask = 0x3F;	/* Default [0:5] */
51 
52 	ACPI_FUNCTION_TRACE(ps_get_next_package_length);
53 
54 	/*
55 	 * Byte 0 bits [6:7] contain the number of additional bytes
56 	 * used to encode the package length, either 0,1,2, or 3
57 	 */
58 	byte_count = (aml[0] >> 6);
59 	parser_state->aml += ((acpi_size)byte_count + 1);
60 
61 	/* Get bytes 3, 2, 1 as needed */
62 
63 	while (byte_count) {
64 		/*
65 		 * Final bit positions for the package length bytes:
66 		 *      Byte3->[20:27]
67 		 *      Byte2->[12:19]
68 		 *      Byte1->[04:11]
69 		 *      Byte0->[00:03]
70 		 */
71 		package_length |= (aml[byte_count] << ((byte_count << 3) - 4));
72 
73 		byte_zero_mask = 0x0F;	/* Use bits [0:3] of byte 0 */
74 		byte_count--;
75 	}
76 
77 	/* Byte 0 is a special case, either bits [0:3] or [0:5] are used */
78 
79 	package_length |= (aml[0] & byte_zero_mask);
80 	return_UINT32(package_length);
81 }
82 
83 /*******************************************************************************
84  *
85  * FUNCTION:    acpi_ps_get_next_package_end
86  *
87  * PARAMETERS:  parser_state        - Current parser state object
88  *
89  * RETURN:      Pointer to end-of-package +1
90  *
91  * DESCRIPTION: Get next package length and return a pointer past the end of
92  *              the package. Consumes the package length field
93  *
94  ******************************************************************************/
95 
96 u8 *acpi_ps_get_next_package_end(struct acpi_parse_state *parser_state)
97 {
98 	u8 *start = parser_state->aml;
99 	u32 package_length;
100 
101 	ACPI_FUNCTION_TRACE(ps_get_next_package_end);
102 
103 	/* Function below updates parser_state->Aml */
104 
105 	package_length = acpi_ps_get_next_package_length(parser_state);
106 
107 	return_PTR(start + package_length);	/* end of package */
108 }
109 
110 /*******************************************************************************
111  *
112  * FUNCTION:    acpi_ps_get_next_namestring
113  *
114  * PARAMETERS:  parser_state        - Current parser state object
115  *
116  * RETURN:      Pointer to the start of the name string (pointer points into
117  *              the AML.
118  *
119  * DESCRIPTION: Get next raw namestring within the AML stream. Handles all name
120  *              prefix characters. Set parser state to point past the string.
121  *              (Name is consumed from the AML.)
122  *
123  ******************************************************************************/
124 
125 char *acpi_ps_get_next_namestring(struct acpi_parse_state *parser_state)
126 {
127 	u8 *start = parser_state->aml;
128 	u8 *end = parser_state->aml;
129 
130 	ACPI_FUNCTION_TRACE(ps_get_next_namestring);
131 
132 	/* Point past any namestring prefix characters (backslash or carat) */
133 
134 	while (ACPI_IS_ROOT_PREFIX(*end) || ACPI_IS_PARENT_PREFIX(*end)) {
135 		end++;
136 	}
137 
138 	/* Decode the path prefix character */
139 
140 	switch (*end) {
141 	case 0:
142 
143 		/* null_name */
144 
145 		if (end == start) {
146 			start = NULL;
147 		}
148 		end++;
149 		break;
150 
151 	case AML_DUAL_NAME_PREFIX:
152 
153 		/* Two name segments */
154 
155 		end += 1 + (2 * ACPI_NAMESEG_SIZE);
156 		break;
157 
158 	case AML_MULTI_NAME_PREFIX:
159 
160 		/* Multiple name segments, 4 chars each, count in next byte */
161 
162 		end += 2 + (*(end + 1) * ACPI_NAMESEG_SIZE);
163 		break;
164 
165 	default:
166 
167 		/* Single name segment */
168 
169 		end += ACPI_NAMESEG_SIZE;
170 		break;
171 	}
172 
173 	parser_state->aml = end;
174 	return_PTR((char *)start);
175 }
176 
177 /*******************************************************************************
178  *
179  * FUNCTION:    acpi_ps_get_next_namepath
180  *
181  * PARAMETERS:  parser_state        - Current parser state object
182  *              arg                 - Where the namepath will be stored
183  *              arg_count           - If the namepath points to a control method
184  *                                    the method's argument is returned here.
185  *              possible_method_call - Whether the namepath can possibly be the
186  *                                    start of a method call
187  *
188  * RETURN:      Status
189  *
190  * DESCRIPTION: Get next name (if method call, return # of required args).
191  *              Names are looked up in the internal namespace to determine
192  *              if the name represents a control method. If a method
193  *              is found, the number of arguments to the method is returned.
194  *              This information is critical for parsing to continue correctly.
195  *
196  ******************************************************************************/
197 
198 acpi_status
199 acpi_ps_get_next_namepath(struct acpi_walk_state *walk_state,
200 			  struct acpi_parse_state *parser_state,
201 			  union acpi_parse_object *arg, u8 possible_method_call)
202 {
203 	acpi_status status;
204 	char *path;
205 	union acpi_parse_object *name_op;
206 	union acpi_operand_object *method_desc;
207 	struct acpi_namespace_node *node;
208 	u8 *start = parser_state->aml;
209 
210 	ACPI_FUNCTION_TRACE(ps_get_next_namepath);
211 
212 	path = acpi_ps_get_next_namestring(parser_state);
213 	acpi_ps_init_op(arg, AML_INT_NAMEPATH_OP);
214 
215 	/* Null path case is allowed, just exit */
216 
217 	if (!path) {
218 		arg->common.value.name = path;
219 		return_ACPI_STATUS(AE_OK);
220 	}
221 
222 	/*
223 	 * Lookup the name in the internal namespace, starting with the current
224 	 * scope. We don't want to add anything new to the namespace here,
225 	 * however, so we use MODE_EXECUTE.
226 	 * Allow searching of the parent tree, but don't open a new scope -
227 	 * we just want to lookup the object (must be mode EXECUTE to perform
228 	 * the upsearch)
229 	 */
230 	status = acpi_ns_lookup(walk_state->scope_info, path,
231 				ACPI_TYPE_ANY, ACPI_IMODE_EXECUTE,
232 				ACPI_NS_SEARCH_PARENT | ACPI_NS_DONT_OPEN_SCOPE,
233 				NULL, &node);
234 
235 	/*
236 	 * If this name is a control method invocation, we must
237 	 * setup the method call
238 	 */
239 	if (ACPI_SUCCESS(status) &&
240 	    possible_method_call && (node->type == ACPI_TYPE_METHOD)) {
241 		if ((GET_CURRENT_ARG_TYPE(walk_state->arg_types) ==
242 		     ARGP_SUPERNAME)
243 		    || (GET_CURRENT_ARG_TYPE(walk_state->arg_types) ==
244 			ARGP_TARGET)) {
245 			/*
246 			 * acpi_ps_get_next_namestring has increased the AML pointer past
247 			 * the method invocation namestring, so we need to restore the
248 			 * saved AML pointer back to the original method invocation
249 			 * namestring.
250 			 */
251 			walk_state->parser_state.aml = start;
252 			walk_state->arg_count = 1;
253 			acpi_ps_init_op(arg, AML_INT_METHODCALL_OP);
254 		}
255 
256 		/* This name is actually a control method invocation */
257 
258 		method_desc = acpi_ns_get_attached_object(node);
259 		ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
260 				  "Control Method invocation %4.4s - %p Desc %p Path=%p\n",
261 				  node->name.ascii, node, method_desc, path));
262 
263 		name_op = acpi_ps_alloc_op(AML_INT_NAMEPATH_OP, start);
264 		if (!name_op) {
265 			return_ACPI_STATUS(AE_NO_MEMORY);
266 		}
267 
268 		/* Change Arg into a METHOD CALL and attach name to it */
269 
270 		acpi_ps_init_op(arg, AML_INT_METHODCALL_OP);
271 		name_op->common.value.name = path;
272 
273 		/* Point METHODCALL/NAME to the METHOD Node */
274 
275 		name_op->common.node = node;
276 		acpi_ps_append_arg(arg, name_op);
277 
278 		if (!method_desc) {
279 			ACPI_ERROR((AE_INFO,
280 				    "Control Method %p has no attached object",
281 				    node));
282 			return_ACPI_STATUS(AE_AML_INTERNAL);
283 		}
284 
285 		ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
286 				  "Control Method - %p Args %X\n",
287 				  node, method_desc->method.param_count));
288 
289 		/* Get the number of arguments to expect */
290 
291 		walk_state->arg_count = method_desc->method.param_count;
292 		return_ACPI_STATUS(AE_OK);
293 	}
294 
295 	/*
296 	 * Special handling if the name was not found during the lookup -
297 	 * some not_found cases are allowed
298 	 */
299 	if (status == AE_NOT_FOUND) {
300 
301 		/* 1) not_found is ok during load pass 1/2 (allow forward references) */
302 
303 		if ((walk_state->parse_flags & ACPI_PARSE_MODE_MASK) !=
304 		    ACPI_PARSE_EXECUTE) {
305 			status = AE_OK;
306 		}
307 
308 		/* 2) not_found during a cond_ref_of(x) is ok by definition */
309 
310 		else if (walk_state->op->common.aml_opcode ==
311 			 AML_CONDITIONAL_REF_OF_OP) {
312 			status = AE_OK;
313 		}
314 
315 		/*
316 		 * 3) not_found while building a Package is ok at this point, we
317 		 * may flag as an error later if slack mode is not enabled.
318 		 * (Some ASL code depends on allowing this behavior)
319 		 */
320 		else if ((arg->common.parent) &&
321 			 ((arg->common.parent->common.aml_opcode ==
322 			   AML_PACKAGE_OP)
323 			  || (arg->common.parent->common.aml_opcode ==
324 			      AML_VARIABLE_PACKAGE_OP))) {
325 			status = AE_OK;
326 		}
327 	}
328 
329 	/* Final exception check (may have been changed from code above) */
330 
331 	if (ACPI_FAILURE(status)) {
332 		ACPI_ERROR_NAMESPACE(walk_state->scope_info, path, status);
333 
334 		if ((walk_state->parse_flags & ACPI_PARSE_MODE_MASK) ==
335 		    ACPI_PARSE_EXECUTE) {
336 
337 			/* Report a control method execution error */
338 
339 			status = acpi_ds_method_error(status, walk_state);
340 		}
341 	}
342 
343 	/* Save the namepath */
344 
345 	arg->common.value.name = path;
346 	return_ACPI_STATUS(status);
347 }
348 
349 /*******************************************************************************
350  *
351  * FUNCTION:    acpi_ps_get_next_simple_arg
352  *
353  * PARAMETERS:  parser_state        - Current parser state object
354  *              arg_type            - The argument type (AML_*_ARG)
355  *              arg                 - Where the argument is returned
356  *
357  * RETURN:      None
358  *
359  * DESCRIPTION: Get the next simple argument (constant, string, or namestring)
360  *
361  ******************************************************************************/
362 
363 void
364 acpi_ps_get_next_simple_arg(struct acpi_parse_state *parser_state,
365 			    u32 arg_type, union acpi_parse_object *arg)
366 {
367 	u32 length;
368 	u16 opcode;
369 	u8 *aml = parser_state->aml;
370 
371 	ACPI_FUNCTION_TRACE_U32(ps_get_next_simple_arg, arg_type);
372 
373 	switch (arg_type) {
374 	case ARGP_BYTEDATA:
375 
376 		/* Get 1 byte from the AML stream */
377 
378 		opcode = AML_BYTE_OP;
379 		arg->common.value.integer = (u64) *aml;
380 		length = 1;
381 		break;
382 
383 	case ARGP_WORDDATA:
384 
385 		/* Get 2 bytes from the AML stream */
386 
387 		opcode = AML_WORD_OP;
388 		ACPI_MOVE_16_TO_64(&arg->common.value.integer, aml);
389 		length = 2;
390 		break;
391 
392 	case ARGP_DWORDDATA:
393 
394 		/* Get 4 bytes from the AML stream */
395 
396 		opcode = AML_DWORD_OP;
397 		ACPI_MOVE_32_TO_64(&arg->common.value.integer, aml);
398 		length = 4;
399 		break;
400 
401 	case ARGP_QWORDDATA:
402 
403 		/* Get 8 bytes from the AML stream */
404 
405 		opcode = AML_QWORD_OP;
406 		ACPI_MOVE_64_TO_64(&arg->common.value.integer, aml);
407 		length = 8;
408 		break;
409 
410 	case ARGP_CHARLIST:
411 
412 		/* Get a pointer to the string, point past the string */
413 
414 		opcode = AML_STRING_OP;
415 		arg->common.value.string = ACPI_CAST_PTR(char, aml);
416 
417 		/* Find the null terminator */
418 
419 		length = 0;
420 		while (aml[length]) {
421 			length++;
422 		}
423 		length++;
424 		break;
425 
426 	case ARGP_NAME:
427 	case ARGP_NAMESTRING:
428 
429 		acpi_ps_init_op(arg, AML_INT_NAMEPATH_OP);
430 		arg->common.value.name =
431 		    acpi_ps_get_next_namestring(parser_state);
432 		return_VOID;
433 
434 	default:
435 
436 		ACPI_ERROR((AE_INFO, "Invalid ArgType 0x%X", arg_type));
437 		return_VOID;
438 	}
439 
440 	acpi_ps_init_op(arg, opcode);
441 	parser_state->aml += length;
442 	return_VOID;
443 }
444 
445 /*******************************************************************************
446  *
447  * FUNCTION:    acpi_ps_get_next_field
448  *
449  * PARAMETERS:  parser_state        - Current parser state object
450  *
451  * RETURN:      A newly allocated FIELD op
452  *
453  * DESCRIPTION: Get next field (named_field, reserved_field, or access_field)
454  *
455  ******************************************************************************/
456 
457 static union acpi_parse_object *acpi_ps_get_next_field(struct acpi_parse_state
458 						       *parser_state)
459 {
460 	u8 *aml;
461 	union acpi_parse_object *field;
462 	union acpi_parse_object *arg = NULL;
463 	u16 opcode;
464 	u32 name;
465 	u8 access_type;
466 	u8 access_attribute;
467 	u8 access_length;
468 	u32 pkg_length;
469 	u8 *pkg_end;
470 	u32 buffer_length;
471 
472 	ACPI_FUNCTION_TRACE(ps_get_next_field);
473 
474 	ASL_CV_CAPTURE_COMMENTS_ONLY(parser_state);
475 	aml = parser_state->aml;
476 
477 	/* Determine field type */
478 
479 	switch (ACPI_GET8(parser_state->aml)) {
480 	case AML_FIELD_OFFSET_OP:
481 
482 		opcode = AML_INT_RESERVEDFIELD_OP;
483 		parser_state->aml++;
484 		break;
485 
486 	case AML_FIELD_ACCESS_OP:
487 
488 		opcode = AML_INT_ACCESSFIELD_OP;
489 		parser_state->aml++;
490 		break;
491 
492 	case AML_FIELD_CONNECTION_OP:
493 
494 		opcode = AML_INT_CONNECTION_OP;
495 		parser_state->aml++;
496 		break;
497 
498 	case AML_FIELD_EXT_ACCESS_OP:
499 
500 		opcode = AML_INT_EXTACCESSFIELD_OP;
501 		parser_state->aml++;
502 		break;
503 
504 	default:
505 
506 		opcode = AML_INT_NAMEDFIELD_OP;
507 		break;
508 	}
509 
510 	/* Allocate a new field op */
511 
512 	field = acpi_ps_alloc_op(opcode, aml);
513 	if (!field) {
514 		return_PTR(NULL);
515 	}
516 
517 	/* Decode the field type */
518 
519 	ASL_CV_CAPTURE_COMMENTS_ONLY(parser_state);
520 	switch (opcode) {
521 	case AML_INT_NAMEDFIELD_OP:
522 
523 		/* Get the 4-character name */
524 
525 		ACPI_MOVE_32_TO_32(&name, parser_state->aml);
526 		acpi_ps_set_name(field, name);
527 		parser_state->aml += ACPI_NAMESEG_SIZE;
528 
529 		ASL_CV_CAPTURE_COMMENTS_ONLY(parser_state);
530 
531 #ifdef ACPI_ASL_COMPILER
532 		/*
533 		 * Because the package length isn't represented as a parse tree object,
534 		 * take comments surrounding this and add to the previously created
535 		 * parse node.
536 		 */
537 		if (field->common.inline_comment) {
538 			field->common.name_comment =
539 			    field->common.inline_comment;
540 		}
541 		field->common.inline_comment = acpi_gbl_current_inline_comment;
542 		acpi_gbl_current_inline_comment = NULL;
543 #endif
544 
545 		/* Get the length which is encoded as a package length */
546 
547 		field->common.value.size =
548 		    acpi_ps_get_next_package_length(parser_state);
549 		break;
550 
551 	case AML_INT_RESERVEDFIELD_OP:
552 
553 		/* Get the length which is encoded as a package length */
554 
555 		field->common.value.size =
556 		    acpi_ps_get_next_package_length(parser_state);
557 		break;
558 
559 	case AML_INT_ACCESSFIELD_OP:
560 	case AML_INT_EXTACCESSFIELD_OP:
561 
562 		/*
563 		 * Get access_type and access_attrib and merge into the field Op
564 		 * access_type is first operand, access_attribute is second. stuff
565 		 * these bytes into the node integer value for convenience.
566 		 */
567 
568 		/* Get the two bytes (Type/Attribute) */
569 
570 		access_type = ACPI_GET8(parser_state->aml);
571 		parser_state->aml++;
572 		access_attribute = ACPI_GET8(parser_state->aml);
573 		parser_state->aml++;
574 
575 		field->common.value.integer = (u8)access_type;
576 		field->common.value.integer |= (u16)(access_attribute << 8);
577 
578 		/* This opcode has a third byte, access_length */
579 
580 		if (opcode == AML_INT_EXTACCESSFIELD_OP) {
581 			access_length = ACPI_GET8(parser_state->aml);
582 			parser_state->aml++;
583 
584 			field->common.value.integer |=
585 			    (u32)(access_length << 16);
586 		}
587 		break;
588 
589 	case AML_INT_CONNECTION_OP:
590 
591 		/*
592 		 * Argument for Connection operator can be either a Buffer
593 		 * (resource descriptor), or a name_string.
594 		 */
595 		aml = parser_state->aml;
596 		if (ACPI_GET8(parser_state->aml) == AML_BUFFER_OP) {
597 			parser_state->aml++;
598 
599 			ASL_CV_CAPTURE_COMMENTS_ONLY(parser_state);
600 			pkg_end = parser_state->aml;
601 			pkg_length =
602 			    acpi_ps_get_next_package_length(parser_state);
603 			pkg_end += pkg_length;
604 
605 			ASL_CV_CAPTURE_COMMENTS_ONLY(parser_state);
606 			if (parser_state->aml < pkg_end) {
607 
608 				/* Non-empty list */
609 
610 				arg =
611 				    acpi_ps_alloc_op(AML_INT_BYTELIST_OP, aml);
612 				if (!arg) {
613 					acpi_ps_free_op(field);
614 					return_PTR(NULL);
615 				}
616 
617 				/* Get the actual buffer length argument */
618 
619 				opcode = ACPI_GET8(parser_state->aml);
620 				parser_state->aml++;
621 
622 				ASL_CV_CAPTURE_COMMENTS_ONLY(parser_state);
623 				switch (opcode) {
624 				case AML_BYTE_OP:	/* AML_BYTEDATA_ARG */
625 
626 					buffer_length =
627 					    ACPI_GET8(parser_state->aml);
628 					parser_state->aml += 1;
629 					break;
630 
631 				case AML_WORD_OP:	/* AML_WORDDATA_ARG */
632 
633 					buffer_length =
634 					    ACPI_GET16(parser_state->aml);
635 					parser_state->aml += 2;
636 					break;
637 
638 				case AML_DWORD_OP:	/* AML_DWORDATA_ARG */
639 
640 					buffer_length =
641 					    ACPI_GET32(parser_state->aml);
642 					parser_state->aml += 4;
643 					break;
644 
645 				default:
646 
647 					buffer_length = 0;
648 					break;
649 				}
650 
651 				/* Fill in bytelist data */
652 
653 				ASL_CV_CAPTURE_COMMENTS_ONLY(parser_state);
654 				arg->named.value.size = buffer_length;
655 				arg->named.data = parser_state->aml;
656 			}
657 
658 			/* Skip to End of byte data */
659 
660 			parser_state->aml = pkg_end;
661 		} else {
662 			arg = acpi_ps_alloc_op(AML_INT_NAMEPATH_OP, aml);
663 			if (!arg) {
664 				acpi_ps_free_op(field);
665 				return_PTR(NULL);
666 			}
667 
668 			/* Get the Namestring argument */
669 
670 			arg->common.value.name =
671 			    acpi_ps_get_next_namestring(parser_state);
672 		}
673 
674 		/* Link the buffer/namestring to parent (CONNECTION_OP) */
675 
676 		acpi_ps_append_arg(field, arg);
677 		break;
678 
679 	default:
680 
681 		/* Opcode was set in previous switch */
682 		break;
683 	}
684 
685 	return_PTR(field);
686 }
687 
688 /*******************************************************************************
689  *
690  * FUNCTION:    acpi_ps_free_field_list
691  *
692  * PARAMETERS:  start               - First Op in field list
693  *
694  * RETURN:      None.
695  *
696  * DESCRIPTION: Free all Op objects inside a field list.
697  *
698  ******************************************************************************/
699 
700 static void acpi_ps_free_field_list(union acpi_parse_object *start)
701 {
702 	union acpi_parse_object *cur = start;
703 	union acpi_parse_object *next;
704 	union acpi_parse_object *arg;
705 
706 	while (cur) {
707 		next = cur->common.next;
708 
709 		/* AML_INT_CONNECTION_OP can have a single argument */
710 
711 		arg = acpi_ps_get_arg(cur, 0);
712 		if (arg) {
713 			acpi_ps_free_op(arg);
714 		}
715 
716 		acpi_ps_free_op(cur);
717 		cur = next;
718 	}
719 }
720 
721 /*******************************************************************************
722  *
723  * FUNCTION:    acpi_ps_get_next_arg
724  *
725  * PARAMETERS:  walk_state          - Current state
726  *              parser_state        - Current parser state object
727  *              arg_type            - The argument type (AML_*_ARG)
728  *              return_arg          - Where the next arg is returned
729  *
730  * RETURN:      Status, and an op object containing the next argument.
731  *
732  * DESCRIPTION: Get next argument (including complex list arguments that require
733  *              pushing the parser stack)
734  *
735  ******************************************************************************/
736 
737 acpi_status
738 acpi_ps_get_next_arg(struct acpi_walk_state *walk_state,
739 		     struct acpi_parse_state *parser_state,
740 		     u32 arg_type, union acpi_parse_object **return_arg)
741 {
742 	union acpi_parse_object *arg = NULL;
743 	union acpi_parse_object *prev = NULL;
744 	union acpi_parse_object *field;
745 	u32 subop;
746 	acpi_status status = AE_OK;
747 
748 	ACPI_FUNCTION_TRACE_PTR(ps_get_next_arg, parser_state);
749 
750 	ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
751 			  "Expected argument type ARGP: %s (%2.2X)\n",
752 			  acpi_ut_get_argument_type_name(arg_type), arg_type));
753 
754 	switch (arg_type) {
755 	case ARGP_BYTEDATA:
756 	case ARGP_WORDDATA:
757 	case ARGP_DWORDDATA:
758 	case ARGP_CHARLIST:
759 	case ARGP_NAME:
760 	case ARGP_NAMESTRING:
761 
762 		/* Constants, strings, and namestrings are all the same size */
763 
764 		arg = acpi_ps_alloc_op(AML_BYTE_OP, parser_state->aml);
765 		if (!arg) {
766 			return_ACPI_STATUS(AE_NO_MEMORY);
767 		}
768 
769 		acpi_ps_get_next_simple_arg(parser_state, arg_type, arg);
770 		break;
771 
772 	case ARGP_PKGLENGTH:
773 
774 		/* Package length, nothing returned */
775 
776 		parser_state->pkg_end =
777 		    acpi_ps_get_next_package_end(parser_state);
778 		break;
779 
780 	case ARGP_FIELDLIST:
781 
782 		if (parser_state->aml < parser_state->pkg_end) {
783 
784 			/* Non-empty list */
785 
786 			while (parser_state->aml < parser_state->pkg_end) {
787 				field = acpi_ps_get_next_field(parser_state);
788 				if (!field) {
789 					if (arg) {
790 						acpi_ps_free_field_list(arg);
791 					}
792 
793 					return_ACPI_STATUS(AE_NO_MEMORY);
794 				}
795 
796 				if (prev) {
797 					prev->common.next = field;
798 				} else {
799 					arg = field;
800 				}
801 				prev = field;
802 			}
803 
804 			/* Skip to End of byte data */
805 
806 			parser_state->aml = parser_state->pkg_end;
807 		}
808 		break;
809 
810 	case ARGP_BYTELIST:
811 
812 		if (parser_state->aml < parser_state->pkg_end) {
813 
814 			/* Non-empty list */
815 
816 			arg = acpi_ps_alloc_op(AML_INT_BYTELIST_OP,
817 					       parser_state->aml);
818 			if (!arg) {
819 				return_ACPI_STATUS(AE_NO_MEMORY);
820 			}
821 
822 			/* Fill in bytelist data */
823 
824 			arg->common.value.size = (u32)
825 			    ACPI_PTR_DIFF(parser_state->pkg_end,
826 					  parser_state->aml);
827 			arg->named.data = parser_state->aml;
828 
829 			/* Skip to End of byte data */
830 
831 			parser_state->aml = parser_state->pkg_end;
832 		}
833 		break;
834 
835 	case ARGP_SIMPLENAME:
836 	case ARGP_NAME_OR_REF:
837 
838 		ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
839 				  "**** SimpleName/NameOrRef: %s (%2.2X)\n",
840 				  acpi_ut_get_argument_type_name(arg_type),
841 				  arg_type));
842 
843 		subop = acpi_ps_peek_opcode(parser_state);
844 		if (subop == 0 ||
845 		    acpi_ps_is_leading_char(subop) ||
846 		    ACPI_IS_ROOT_PREFIX(subop) ||
847 		    ACPI_IS_PARENT_PREFIX(subop)) {
848 
849 			/* null_name or name_string */
850 
851 			arg =
852 			    acpi_ps_alloc_op(AML_INT_NAMEPATH_OP,
853 					     parser_state->aml);
854 			if (!arg) {
855 				return_ACPI_STATUS(AE_NO_MEMORY);
856 			}
857 
858 			status =
859 			    acpi_ps_get_next_namepath(walk_state, parser_state,
860 						      arg,
861 						      ACPI_NOT_METHOD_CALL);
862 			if (ACPI_FAILURE(status)) {
863 				acpi_ps_free_op(arg);
864 				return_ACPI_STATUS(status);
865 			}
866 		} else {
867 			/* Single complex argument, nothing returned */
868 
869 			walk_state->arg_count = 1;
870 		}
871 		break;
872 
873 	case ARGP_TARGET:
874 	case ARGP_SUPERNAME:
875 
876 		ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
877 				  "**** Target/Supername: %s (%2.2X)\n",
878 				  acpi_ut_get_argument_type_name(arg_type),
879 				  arg_type));
880 
881 		subop = acpi_ps_peek_opcode(parser_state);
882 		if (subop == 0 ||
883 		    acpi_ps_is_leading_char(subop) ||
884 		    ACPI_IS_ROOT_PREFIX(subop) ||
885 		    ACPI_IS_PARENT_PREFIX(subop)) {
886 
887 			/* NULL target (zero). Convert to a NULL namepath */
888 
889 			arg =
890 			    acpi_ps_alloc_op(AML_INT_NAMEPATH_OP,
891 					     parser_state->aml);
892 			if (!arg) {
893 				return_ACPI_STATUS(AE_NO_MEMORY);
894 			}
895 
896 			status =
897 			    acpi_ps_get_next_namepath(walk_state, parser_state,
898 						      arg,
899 						      ACPI_POSSIBLE_METHOD_CALL);
900 			if (ACPI_FAILURE(status)) {
901 				acpi_ps_free_op(arg);
902 				return_ACPI_STATUS(status);
903 			}
904 
905 			if (arg->common.aml_opcode == AML_INT_METHODCALL_OP) {
906 
907 				/* Free method call op and corresponding namestring sub-ob */
908 
909 				acpi_ps_free_op(arg->common.value.arg);
910 				acpi_ps_free_op(arg);
911 				arg = NULL;
912 				walk_state->arg_count = 1;
913 			}
914 		} else {
915 			/* Single complex argument, nothing returned */
916 
917 			walk_state->arg_count = 1;
918 		}
919 		break;
920 
921 	case ARGP_DATAOBJ:
922 	case ARGP_TERMARG:
923 
924 		ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
925 				  "**** TermArg/DataObj: %s (%2.2X)\n",
926 				  acpi_ut_get_argument_type_name(arg_type),
927 				  arg_type));
928 
929 		/* Single complex argument, nothing returned */
930 
931 		walk_state->arg_count = 1;
932 		break;
933 
934 	case ARGP_DATAOBJLIST:
935 	case ARGP_TERMLIST:
936 	case ARGP_OBJLIST:
937 
938 		if (parser_state->aml < parser_state->pkg_end) {
939 
940 			/* Non-empty list of variable arguments, nothing returned */
941 
942 			walk_state->arg_count = ACPI_VAR_ARGS;
943 		}
944 		break;
945 
946 	default:
947 
948 		ACPI_ERROR((AE_INFO, "Invalid ArgType: 0x%X", arg_type));
949 		status = AE_AML_OPERAND_TYPE;
950 		break;
951 	}
952 
953 	*return_arg = arg;
954 	return_ACPI_STATUS(status);
955 }
956