xref: /linux/drivers/acpi/acpica/rsxface.c (revision ca55b2fef3a9373fcfc30f82fd26bc7fccbda732)
1 /*******************************************************************************
2  *
3  * Module Name: rsxface - Public interfaces to the resource manager
4  *
5  ******************************************************************************/
6 
7 /*
8  * Copyright (C) 2000 - 2015, Intel Corp.
9  * All rights reserved.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions, and the following disclaimer,
16  *    without modification.
17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
18  *    substantially similar to the "NO WARRANTY" disclaimer below
19  *    ("Disclaimer") and any redistribution must be conditioned upon
20  *    including a substantially similar Disclaimer requirement for further
21  *    binary redistribution.
22  * 3. Neither the names of the above-listed copyright holders nor the names
23  *    of any contributors may be used to endorse or promote products derived
24  *    from this software without specific prior written permission.
25  *
26  * Alternatively, this software may be distributed under the terms of the
27  * GNU General Public License ("GPL") version 2 as published by the Free
28  * Software Foundation.
29  *
30  * NO WARRANTY
31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
41  * POSSIBILITY OF SUCH DAMAGES.
42  */
43 
44 #define EXPORT_ACPI_INTERFACES
45 
46 #include <acpi/acpi.h>
47 #include "accommon.h"
48 #include "acresrc.h"
49 #include "acnamesp.h"
50 
51 #define _COMPONENT          ACPI_RESOURCES
52 ACPI_MODULE_NAME("rsxface")
53 
54 /* Local macros for 16,32-bit to 64-bit conversion */
55 #define ACPI_COPY_FIELD(out, in, field)  ((out)->field = (in)->field)
56 #define ACPI_COPY_ADDRESS(out, in)                      \
57 	ACPI_COPY_FIELD(out, in, resource_type);             \
58 	ACPI_COPY_FIELD(out, in, producer_consumer);         \
59 	ACPI_COPY_FIELD(out, in, decode);                    \
60 	ACPI_COPY_FIELD(out, in, min_address_fixed);         \
61 	ACPI_COPY_FIELD(out, in, max_address_fixed);         \
62 	ACPI_COPY_FIELD(out, in, info);                      \
63 	ACPI_COPY_FIELD(out, in, address.granularity);       \
64 	ACPI_COPY_FIELD(out, in, address.minimum);           \
65 	ACPI_COPY_FIELD(out, in, address.maximum);           \
66 	ACPI_COPY_FIELD(out, in, address.translation_offset); \
67 	ACPI_COPY_FIELD(out, in, address.address_length);    \
68 	ACPI_COPY_FIELD(out, in, resource_source);
69 /* Local prototypes */
70 static acpi_status
71 acpi_rs_match_vendor_resource(struct acpi_resource *resource, void *context);
72 
73 static acpi_status
74 acpi_rs_validate_parameters(acpi_handle device_handle,
75 			    struct acpi_buffer *buffer,
76 			    struct acpi_namespace_node **return_node);
77 
78 /*******************************************************************************
79  *
80  * FUNCTION:    acpi_rs_validate_parameters
81  *
82  * PARAMETERS:  device_handle   - Handle to a device
83  *              buffer          - Pointer to a data buffer
84  *              return_node     - Pointer to where the device node is returned
85  *
86  * RETURN:      Status
87  *
88  * DESCRIPTION: Common parameter validation for resource interfaces
89  *
90  ******************************************************************************/
91 
92 static acpi_status
93 acpi_rs_validate_parameters(acpi_handle device_handle,
94 			    struct acpi_buffer *buffer,
95 			    struct acpi_namespace_node **return_node)
96 {
97 	acpi_status status;
98 	struct acpi_namespace_node *node;
99 
100 	ACPI_FUNCTION_TRACE(rs_validate_parameters);
101 
102 	/*
103 	 * Must have a valid handle to an ACPI device
104 	 */
105 	if (!device_handle) {
106 		return_ACPI_STATUS(AE_BAD_PARAMETER);
107 	}
108 
109 	node = acpi_ns_validate_handle(device_handle);
110 	if (!node) {
111 		return_ACPI_STATUS(AE_BAD_PARAMETER);
112 	}
113 
114 	if (node->type != ACPI_TYPE_DEVICE) {
115 		return_ACPI_STATUS(AE_TYPE);
116 	}
117 
118 	/*
119 	 * Validate the user buffer object
120 	 *
121 	 * if there is a non-zero buffer length we also need a valid pointer in
122 	 * the buffer. If it's a zero buffer length, we'll be returning the
123 	 * needed buffer size (later), so keep going.
124 	 */
125 	status = acpi_ut_validate_buffer(buffer);
126 	if (ACPI_FAILURE(status)) {
127 		return_ACPI_STATUS(status);
128 	}
129 
130 	*return_node = node;
131 	return_ACPI_STATUS(AE_OK);
132 }
133 
134 /*******************************************************************************
135  *
136  * FUNCTION:    acpi_get_irq_routing_table
137  *
138  * PARAMETERS:  device_handle   - Handle to the Bus device we are querying
139  *              ret_buffer      - Pointer to a buffer to receive the
140  *                                current resources for the device
141  *
142  * RETURN:      Status
143  *
144  * DESCRIPTION: This function is called to get the IRQ routing table for a
145  *              specific bus. The caller must first acquire a handle for the
146  *              desired bus. The routine table is placed in the buffer pointed
147  *              to by the ret_buffer variable parameter.
148  *
149  *              If the function fails an appropriate status will be returned
150  *              and the value of ret_buffer is undefined.
151  *
152  *              This function attempts to execute the _PRT method contained in
153  *              the object indicated by the passed device_handle.
154  *
155  ******************************************************************************/
156 
157 acpi_status
158 acpi_get_irq_routing_table(acpi_handle device_handle,
159 			   struct acpi_buffer *ret_buffer)
160 {
161 	acpi_status status;
162 	struct acpi_namespace_node *node;
163 
164 	ACPI_FUNCTION_TRACE(acpi_get_irq_routing_table);
165 
166 	/* Validate parameters then dispatch to internal routine */
167 
168 	status = acpi_rs_validate_parameters(device_handle, ret_buffer, &node);
169 	if (ACPI_FAILURE(status)) {
170 		return_ACPI_STATUS(status);
171 	}
172 
173 	status = acpi_rs_get_prt_method_data(node, ret_buffer);
174 	return_ACPI_STATUS(status);
175 }
176 
177 ACPI_EXPORT_SYMBOL(acpi_get_irq_routing_table)
178 
179 /*******************************************************************************
180  *
181  * FUNCTION:    acpi_get_current_resources
182  *
183  * PARAMETERS:  device_handle   - Handle to the device object for the
184  *                                device we are querying
185  *              ret_buffer      - Pointer to a buffer to receive the
186  *                                current resources for the device
187  *
188  * RETURN:      Status
189  *
190  * DESCRIPTION: This function is called to get the current resources for a
191  *              specific device. The caller must first acquire a handle for
192  *              the desired device. The resource data is placed in the buffer
193  *              pointed to by the ret_buffer variable parameter.
194  *
195  *              If the function fails an appropriate status will be returned
196  *              and the value of ret_buffer is undefined.
197  *
198  *              This function attempts to execute the _CRS method contained in
199  *              the object indicated by the passed device_handle.
200  *
201  ******************************************************************************/
202 acpi_status
203 acpi_get_current_resources(acpi_handle device_handle,
204 			   struct acpi_buffer *ret_buffer)
205 {
206 	acpi_status status;
207 	struct acpi_namespace_node *node;
208 
209 	ACPI_FUNCTION_TRACE(acpi_get_current_resources);
210 
211 	/* Validate parameters then dispatch to internal routine */
212 
213 	status = acpi_rs_validate_parameters(device_handle, ret_buffer, &node);
214 	if (ACPI_FAILURE(status)) {
215 		return_ACPI_STATUS(status);
216 	}
217 
218 	status = acpi_rs_get_crs_method_data(node, ret_buffer);
219 	return_ACPI_STATUS(status);
220 }
221 
222 ACPI_EXPORT_SYMBOL(acpi_get_current_resources)
223 #ifdef ACPI_FUTURE_USAGE
224 /*******************************************************************************
225  *
226  * FUNCTION:    acpi_get_possible_resources
227  *
228  * PARAMETERS:  device_handle   - Handle to the device object for the
229  *                                device we are querying
230  *              ret_buffer      - Pointer to a buffer to receive the
231  *                                resources for the device
232  *
233  * RETURN:      Status
234  *
235  * DESCRIPTION: This function is called to get a list of the possible resources
236  *              for a specific device. The caller must first acquire a handle
237  *              for the desired device. The resource data is placed in the
238  *              buffer pointed to by the ret_buffer variable.
239  *
240  *              If the function fails an appropriate status will be returned
241  *              and the value of ret_buffer is undefined.
242  *
243  ******************************************************************************/
244 acpi_status
245 acpi_get_possible_resources(acpi_handle device_handle,
246 			    struct acpi_buffer *ret_buffer)
247 {
248 	acpi_status status;
249 	struct acpi_namespace_node *node;
250 
251 	ACPI_FUNCTION_TRACE(acpi_get_possible_resources);
252 
253 	/* Validate parameters then dispatch to internal routine */
254 
255 	status = acpi_rs_validate_parameters(device_handle, ret_buffer, &node);
256 	if (ACPI_FAILURE(status)) {
257 		return_ACPI_STATUS(status);
258 	}
259 
260 	status = acpi_rs_get_prs_method_data(node, ret_buffer);
261 	return_ACPI_STATUS(status);
262 }
263 
264 ACPI_EXPORT_SYMBOL(acpi_get_possible_resources)
265 #endif				/*  ACPI_FUTURE_USAGE  */
266 /*******************************************************************************
267  *
268  * FUNCTION:    acpi_set_current_resources
269  *
270  * PARAMETERS:  device_handle   - Handle to the device object for the
271  *                                device we are setting resources
272  *              in_buffer       - Pointer to a buffer containing the
273  *                                resources to be set for the device
274  *
275  * RETURN:      Status
276  *
277  * DESCRIPTION: This function is called to set the current resources for a
278  *              specific device. The caller must first acquire a handle for
279  *              the desired device. The resource data is passed to the routine
280  *              the buffer pointed to by the in_buffer variable.
281  *
282  ******************************************************************************/
283 acpi_status
284 acpi_set_current_resources(acpi_handle device_handle,
285 			   struct acpi_buffer *in_buffer)
286 {
287 	acpi_status status;
288 	struct acpi_namespace_node *node;
289 
290 	ACPI_FUNCTION_TRACE(acpi_set_current_resources);
291 
292 	/* Validate the buffer, don't allow zero length */
293 
294 	if ((!in_buffer) || (!in_buffer->pointer) || (!in_buffer->length)) {
295 		return_ACPI_STATUS(AE_BAD_PARAMETER);
296 	}
297 
298 	/* Validate parameters then dispatch to internal routine */
299 
300 	status = acpi_rs_validate_parameters(device_handle, in_buffer, &node);
301 	if (ACPI_FAILURE(status)) {
302 		return_ACPI_STATUS(status);
303 	}
304 
305 	status = acpi_rs_set_srs_method_data(node, in_buffer);
306 	return_ACPI_STATUS(status);
307 }
308 
309 ACPI_EXPORT_SYMBOL(acpi_set_current_resources)
310 
311 /*******************************************************************************
312  *
313  * FUNCTION:    acpi_get_event_resources
314  *
315  * PARAMETERS:  device_handle   - Handle to the device object for the
316  *                                device we are getting resources
317  *              in_buffer       - Pointer to a buffer containing the
318  *                                resources to be set for the device
319  *
320  * RETURN:      Status
321  *
322  * DESCRIPTION: This function is called to get the event resources for a
323  *              specific device. The caller must first acquire a handle for
324  *              the desired device. The resource data is passed to the routine
325  *              the buffer pointed to by the in_buffer variable. Uses the
326  *              _AEI method.
327  *
328  ******************************************************************************/
329 acpi_status
330 acpi_get_event_resources(acpi_handle device_handle,
331 			 struct acpi_buffer *ret_buffer)
332 {
333 	acpi_status status;
334 	struct acpi_namespace_node *node;
335 
336 	ACPI_FUNCTION_TRACE(acpi_get_event_resources);
337 
338 	/* Validate parameters then dispatch to internal routine */
339 
340 	status = acpi_rs_validate_parameters(device_handle, ret_buffer, &node);
341 	if (ACPI_FAILURE(status)) {
342 		return_ACPI_STATUS(status);
343 	}
344 
345 	status = acpi_rs_get_aei_method_data(node, ret_buffer);
346 	return_ACPI_STATUS(status);
347 }
348 
349 ACPI_EXPORT_SYMBOL(acpi_get_event_resources)
350 
351 /******************************************************************************
352  *
353  * FUNCTION:    acpi_resource_to_address64
354  *
355  * PARAMETERS:  resource        - Pointer to a resource
356  *              out             - Pointer to the users's return buffer
357  *                                (a struct acpi_resource_address64)
358  *
359  * RETURN:      Status
360  *
361  * DESCRIPTION: If the resource is an address16, address32, or address64,
362  *              copy it to the address64 return buffer. This saves the
363  *              caller from having to duplicate code for different-sized
364  *              addresses.
365  *
366  ******************************************************************************/
367 acpi_status
368 acpi_resource_to_address64(struct acpi_resource *resource,
369 			   struct acpi_resource_address64 *out)
370 {
371 	struct acpi_resource_address16 *address16;
372 	struct acpi_resource_address32 *address32;
373 
374 	if (!resource || !out) {
375 		return (AE_BAD_PARAMETER);
376 	}
377 
378 	/* Convert 16 or 32 address descriptor to 64 */
379 
380 	switch (resource->type) {
381 	case ACPI_RESOURCE_TYPE_ADDRESS16:
382 
383 		address16 =
384 		    ACPI_CAST_PTR(struct acpi_resource_address16,
385 				  &resource->data);
386 		ACPI_COPY_ADDRESS(out, address16);
387 		break;
388 
389 	case ACPI_RESOURCE_TYPE_ADDRESS32:
390 
391 		address32 =
392 		    ACPI_CAST_PTR(struct acpi_resource_address32,
393 				  &resource->data);
394 		ACPI_COPY_ADDRESS(out, address32);
395 		break;
396 
397 	case ACPI_RESOURCE_TYPE_ADDRESS64:
398 
399 		/* Simple copy for 64 bit source */
400 
401 		memcpy(out, &resource->data,
402 		       sizeof(struct acpi_resource_address64));
403 		break;
404 
405 	default:
406 
407 		return (AE_BAD_PARAMETER);
408 	}
409 
410 	return (AE_OK);
411 }
412 
413 ACPI_EXPORT_SYMBOL(acpi_resource_to_address64)
414 
415 /*******************************************************************************
416  *
417  * FUNCTION:    acpi_get_vendor_resource
418  *
419  * PARAMETERS:  device_handle   - Handle for the parent device object
420  *              name            - Method name for the parent resource
421  *                                (METHOD_NAME__CRS or METHOD_NAME__PRS)
422  *              uuid            - Pointer to the UUID to be matched.
423  *                                includes both subtype and 16-byte UUID
424  *              ret_buffer      - Where the vendor resource is returned
425  *
426  * RETURN:      Status
427  *
428  * DESCRIPTION: Walk a resource template for the specified device to find a
429  *              vendor-defined resource that matches the supplied UUID and
430  *              UUID subtype. Returns a struct acpi_resource of type Vendor.
431  *
432  ******************************************************************************/
433 acpi_status
434 acpi_get_vendor_resource(acpi_handle device_handle,
435 			 char *name,
436 			 struct acpi_vendor_uuid * uuid,
437 			 struct acpi_buffer * ret_buffer)
438 {
439 	struct acpi_vendor_walk_info info;
440 	acpi_status status;
441 
442 	/* Other parameters are validated by acpi_walk_resources */
443 
444 	if (!uuid || !ret_buffer) {
445 		return (AE_BAD_PARAMETER);
446 	}
447 
448 	info.uuid = uuid;
449 	info.buffer = ret_buffer;
450 	info.status = AE_NOT_EXIST;
451 
452 	/* Walk the _CRS or _PRS resource list for this device */
453 
454 	status =
455 	    acpi_walk_resources(device_handle, name,
456 				acpi_rs_match_vendor_resource, &info);
457 	if (ACPI_FAILURE(status)) {
458 		return (status);
459 	}
460 
461 	return (info.status);
462 }
463 
464 ACPI_EXPORT_SYMBOL(acpi_get_vendor_resource)
465 
466 /*******************************************************************************
467  *
468  * FUNCTION:    acpi_rs_match_vendor_resource
469  *
470  * PARAMETERS:  acpi_walk_resource_callback
471  *
472  * RETURN:      Status
473  *
474  * DESCRIPTION: Match a vendor resource via the ACPI 3.0 UUID
475  *
476  ******************************************************************************/
477 static acpi_status
478 acpi_rs_match_vendor_resource(struct acpi_resource *resource, void *context)
479 {
480 	struct acpi_vendor_walk_info *info = context;
481 	struct acpi_resource_vendor_typed *vendor;
482 	struct acpi_buffer *buffer;
483 	acpi_status status;
484 
485 	/* Ignore all descriptors except Vendor */
486 
487 	if (resource->type != ACPI_RESOURCE_TYPE_VENDOR) {
488 		return (AE_OK);
489 	}
490 
491 	vendor = &resource->data.vendor_typed;
492 
493 	/*
494 	 * For a valid match, these conditions must hold:
495 	 *
496 	 * 1) Length of descriptor data must be at least as long as a UUID struct
497 	 * 2) The UUID subtypes must match
498 	 * 3) The UUID data must match
499 	 */
500 	if ((vendor->byte_length < (ACPI_UUID_LENGTH + 1)) ||
501 	    (vendor->uuid_subtype != info->uuid->subtype) ||
502 	    (memcmp(vendor->uuid, info->uuid->data, ACPI_UUID_LENGTH))) {
503 		return (AE_OK);
504 	}
505 
506 	/* Validate/Allocate/Clear caller buffer */
507 
508 	buffer = info->buffer;
509 	status = acpi_ut_initialize_buffer(buffer, resource->length);
510 	if (ACPI_FAILURE(status)) {
511 		return (status);
512 	}
513 
514 	/* Found the correct resource, copy and return it */
515 
516 	memcpy(buffer->pointer, resource, resource->length);
517 	buffer->length = resource->length;
518 
519 	/* Found the desired descriptor, terminate resource walk */
520 
521 	info->status = AE_OK;
522 	return (AE_CTRL_TERMINATE);
523 }
524 
525 /*******************************************************************************
526  *
527  * FUNCTION:    acpi_walk_resource_buffer
528  *
529  * PARAMETERS:  buffer          - Formatted buffer returned by one of the
530  *                                various Get*Resource functions
531  *              user_function   - Called for each resource
532  *              context         - Passed to user_function
533  *
534  * RETURN:      Status
535  *
536  * DESCRIPTION: Walks the input resource template. The user_function is called
537  *              once for each resource in the list.
538  *
539  ******************************************************************************/
540 
541 acpi_status
542 acpi_walk_resource_buffer(struct acpi_buffer * buffer,
543 			  acpi_walk_resource_callback user_function,
544 			  void *context)
545 {
546 	acpi_status status = AE_OK;
547 	struct acpi_resource *resource;
548 	struct acpi_resource *resource_end;
549 
550 	ACPI_FUNCTION_TRACE(acpi_walk_resource_buffer);
551 
552 	/* Parameter validation */
553 
554 	if (!buffer || !buffer->pointer || !user_function) {
555 		return_ACPI_STATUS(AE_BAD_PARAMETER);
556 	}
557 
558 	/* Buffer contains the resource list and length */
559 
560 	resource = ACPI_CAST_PTR(struct acpi_resource, buffer->pointer);
561 	resource_end =
562 	    ACPI_ADD_PTR(struct acpi_resource, buffer->pointer, buffer->length);
563 
564 	/* Walk the resource list until the end_tag is found (or buffer end) */
565 
566 	while (resource < resource_end) {
567 
568 		/* Sanity check the resource type */
569 
570 		if (resource->type > ACPI_RESOURCE_TYPE_MAX) {
571 			status = AE_AML_INVALID_RESOURCE_TYPE;
572 			break;
573 		}
574 
575 		/* Sanity check the length. It must not be zero, or we loop forever */
576 
577 		if (!resource->length) {
578 			return_ACPI_STATUS(AE_AML_BAD_RESOURCE_LENGTH);
579 		}
580 
581 		/* Invoke the user function, abort on any error returned */
582 
583 		status = user_function(resource, context);
584 		if (ACPI_FAILURE(status)) {
585 			if (status == AE_CTRL_TERMINATE) {
586 
587 				/* This is an OK termination by the user function */
588 
589 				status = AE_OK;
590 			}
591 			break;
592 		}
593 
594 		/* end_tag indicates end-of-list */
595 
596 		if (resource->type == ACPI_RESOURCE_TYPE_END_TAG) {
597 			break;
598 		}
599 
600 		/* Get the next resource descriptor */
601 
602 		resource = ACPI_NEXT_RESOURCE(resource);
603 	}
604 
605 	return_ACPI_STATUS(status);
606 }
607 
608 ACPI_EXPORT_SYMBOL(acpi_walk_resource_buffer)
609 
610 /*******************************************************************************
611  *
612  * FUNCTION:    acpi_walk_resources
613  *
614  * PARAMETERS:  device_handle   - Handle to the device object for the
615  *                                device we are querying
616  *              name            - Method name of the resources we want.
617  *                                (METHOD_NAME__CRS, METHOD_NAME__PRS, or
618  *                                METHOD_NAME__AEI)
619  *              user_function   - Called for each resource
620  *              context         - Passed to user_function
621  *
622  * RETURN:      Status
623  *
624  * DESCRIPTION: Retrieves the current or possible resource list for the
625  *              specified device. The user_function is called once for
626  *              each resource in the list.
627  *
628  ******************************************************************************/
629 acpi_status
630 acpi_walk_resources(acpi_handle device_handle,
631 		    char *name,
632 		    acpi_walk_resource_callback user_function, void *context)
633 {
634 	acpi_status status;
635 	struct acpi_buffer buffer;
636 
637 	ACPI_FUNCTION_TRACE(acpi_walk_resources);
638 
639 	/* Parameter validation */
640 
641 	if (!device_handle || !user_function || !name ||
642 	    (!ACPI_COMPARE_NAME(name, METHOD_NAME__CRS) &&
643 	     !ACPI_COMPARE_NAME(name, METHOD_NAME__PRS) &&
644 	     !ACPI_COMPARE_NAME(name, METHOD_NAME__AEI))) {
645 		return_ACPI_STATUS(AE_BAD_PARAMETER);
646 	}
647 
648 	/* Get the _CRS/_PRS/_AEI resource list */
649 
650 	buffer.length = ACPI_ALLOCATE_LOCAL_BUFFER;
651 	status = acpi_rs_get_method_data(device_handle, name, &buffer);
652 	if (ACPI_FAILURE(status)) {
653 		return_ACPI_STATUS(status);
654 	}
655 
656 	/* Walk the resource list and cleanup */
657 
658 	status = acpi_walk_resource_buffer(&buffer, user_function, context);
659 	ACPI_FREE(buffer.pointer);
660 	return_ACPI_STATUS(status);
661 }
662 
663 ACPI_EXPORT_SYMBOL(acpi_walk_resources)
664