xref: /linux/drivers/acpi/acpica/nsxfeval.c (revision 4413e16d9d21673bb5048a2e542f1aaa00015c2e)
1 /*******************************************************************************
2  *
3  * Module Name: nsxfeval - Public interfaces to the ACPI subsystem
4  *                         ACPI Object evaluation interfaces
5  *
6  ******************************************************************************/
7 
8 /*
9  * Copyright (C) 2000 - 2012, Intel Corp.
10  * All rights reserved.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions, and the following disclaimer,
17  *    without modification.
18  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
19  *    substantially similar to the "NO WARRANTY" disclaimer below
20  *    ("Disclaimer") and any redistribution must be conditioned upon
21  *    including a substantially similar Disclaimer requirement for further
22  *    binary redistribution.
23  * 3. Neither the names of the above-listed copyright holders nor the names
24  *    of any contributors may be used to endorse or promote products derived
25  *    from this software without specific prior written permission.
26  *
27  * Alternatively, this software may be distributed under the terms of the
28  * GNU General Public License ("GPL") version 2 as published by the Free
29  * Software Foundation.
30  *
31  * NO WARRANTY
32  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
33  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
34  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
35  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
36  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
37  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
38  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
39  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
40  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
41  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
42  * POSSIBILITY OF SUCH DAMAGES.
43  */
44 
45 #include <linux/export.h>
46 #include <acpi/acpi.h>
47 #include "accommon.h"
48 #include "acnamesp.h"
49 #include "acinterp.h"
50 
51 #define _COMPONENT          ACPI_NAMESPACE
52 ACPI_MODULE_NAME("nsxfeval")
53 
54 /* Local prototypes */
55 static void acpi_ns_resolve_references(struct acpi_evaluate_info *info);
56 
57 /*******************************************************************************
58  *
59  * FUNCTION:    acpi_evaluate_object_typed
60  *
61  * PARAMETERS:  handle              - Object handle (optional)
62  *              pathname            - Object pathname (optional)
63  *              external_params     - List of parameters to pass to method,
64  *                                    terminated by NULL.  May be NULL
65  *                                    if no parameters are being passed.
66  *              return_buffer       - Where to put method's return value (if
67  *                                    any).  If NULL, no value is returned.
68  *              return_type         - Expected type of return object
69  *
70  * RETURN:      Status
71  *
72  * DESCRIPTION: Find and evaluate the given object, passing the given
73  *              parameters if necessary.  One of "Handle" or "Pathname" must
74  *              be valid (non-null)
75  *
76  ******************************************************************************/
77 
78 acpi_status
79 acpi_evaluate_object_typed(acpi_handle handle,
80 			   acpi_string pathname,
81 			   struct acpi_object_list *external_params,
82 			   struct acpi_buffer *return_buffer,
83 			   acpi_object_type return_type)
84 {
85 	acpi_status status;
86 	u8 must_free = FALSE;
87 
88 	ACPI_FUNCTION_TRACE(acpi_evaluate_object_typed);
89 
90 	/* Return buffer must be valid */
91 
92 	if (!return_buffer) {
93 		return_ACPI_STATUS(AE_BAD_PARAMETER);
94 	}
95 
96 	if (return_buffer->length == ACPI_ALLOCATE_BUFFER) {
97 		must_free = TRUE;
98 	}
99 
100 	/* Evaluate the object */
101 
102 	status =
103 	    acpi_evaluate_object(handle, pathname, external_params,
104 				 return_buffer);
105 	if (ACPI_FAILURE(status)) {
106 		return_ACPI_STATUS(status);
107 	}
108 
109 	/* Type ANY means "don't care" */
110 
111 	if (return_type == ACPI_TYPE_ANY) {
112 		return_ACPI_STATUS(AE_OK);
113 	}
114 
115 	if (return_buffer->length == 0) {
116 
117 		/* Error because caller specifically asked for a return value */
118 
119 		ACPI_ERROR((AE_INFO, "No return value"));
120 		return_ACPI_STATUS(AE_NULL_OBJECT);
121 	}
122 
123 	/* Examine the object type returned from evaluate_object */
124 
125 	if (((union acpi_object *)return_buffer->pointer)->type == return_type) {
126 		return_ACPI_STATUS(AE_OK);
127 	}
128 
129 	/* Return object type does not match requested type */
130 
131 	ACPI_ERROR((AE_INFO,
132 		    "Incorrect return type [%s] requested [%s]",
133 		    acpi_ut_get_type_name(((union acpi_object *)return_buffer->
134 					   pointer)->type),
135 		    acpi_ut_get_type_name(return_type)));
136 
137 	if (must_free) {
138 
139 		/* Caller used ACPI_ALLOCATE_BUFFER, free the return buffer */
140 
141 		ACPI_FREE(return_buffer->pointer);
142 		return_buffer->pointer = NULL;
143 	}
144 
145 	return_buffer->length = 0;
146 	return_ACPI_STATUS(AE_TYPE);
147 }
148 
149 ACPI_EXPORT_SYMBOL(acpi_evaluate_object_typed)
150 
151 /*******************************************************************************
152  *
153  * FUNCTION:    acpi_evaluate_object
154  *
155  * PARAMETERS:  handle              - Object handle (optional)
156  *              pathname            - Object pathname (optional)
157  *              external_params     - List of parameters to pass to method,
158  *                                    terminated by NULL.  May be NULL
159  *                                    if no parameters are being passed.
160  *              return_buffer       - Where to put method's return value (if
161  *                                    any).  If NULL, no value is returned.
162  *
163  * RETURN:      Status
164  *
165  * DESCRIPTION: Find and evaluate the given object, passing the given
166  *              parameters if necessary.  One of "Handle" or "Pathname" must
167  *              be valid (non-null)
168  *
169  ******************************************************************************/
170 acpi_status
171 acpi_evaluate_object(acpi_handle handle,
172 		     acpi_string pathname,
173 		     struct acpi_object_list *external_params,
174 		     struct acpi_buffer *return_buffer)
175 {
176 	acpi_status status;
177 	struct acpi_evaluate_info *info;
178 	acpi_size buffer_space_needed;
179 	u32 i;
180 
181 	ACPI_FUNCTION_TRACE(acpi_evaluate_object);
182 
183 	/* Allocate and initialize the evaluation information block */
184 
185 	info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
186 	if (!info) {
187 		return_ACPI_STATUS(AE_NO_MEMORY);
188 	}
189 
190 	info->pathname = pathname;
191 
192 	/* Convert and validate the device handle */
193 
194 	info->prefix_node = acpi_ns_validate_handle(handle);
195 	if (!info->prefix_node) {
196 		status = AE_BAD_PARAMETER;
197 		goto cleanup;
198 	}
199 
200 	/*
201 	 * If there are parameters to be passed to a control method, the external
202 	 * objects must all be converted to internal objects
203 	 */
204 	if (external_params && external_params->count) {
205 		/*
206 		 * Allocate a new parameter block for the internal objects
207 		 * Add 1 to count to allow for null terminated internal list
208 		 */
209 		info->parameters = ACPI_ALLOCATE_ZEROED(((acpi_size)
210 							 external_params->
211 							 count +
212 							 1) * sizeof(void *));
213 		if (!info->parameters) {
214 			status = AE_NO_MEMORY;
215 			goto cleanup;
216 		}
217 
218 		/* Convert each external object in the list to an internal object */
219 
220 		for (i = 0; i < external_params->count; i++) {
221 			status =
222 			    acpi_ut_copy_eobject_to_iobject(&external_params->
223 							    pointer[i],
224 							    &info->
225 							    parameters[i]);
226 			if (ACPI_FAILURE(status)) {
227 				goto cleanup;
228 			}
229 		}
230 		info->parameters[external_params->count] = NULL;
231 	}
232 
233 	/*
234 	 * Three major cases:
235 	 * 1) Fully qualified pathname
236 	 * 2) No handle, not fully qualified pathname (error)
237 	 * 3) Valid handle
238 	 */
239 	if ((pathname) && (acpi_ns_valid_root_prefix(pathname[0]))) {
240 
241 		/* The path is fully qualified, just evaluate by name */
242 
243 		info->prefix_node = NULL;
244 		status = acpi_ns_evaluate(info);
245 	} else if (!handle) {
246 		/*
247 		 * A handle is optional iff a fully qualified pathname is specified.
248 		 * Since we've already handled fully qualified names above, this is
249 		 * an error
250 		 */
251 		if (!pathname) {
252 			ACPI_DEBUG_PRINT((ACPI_DB_INFO,
253 					  "Both Handle and Pathname are NULL"));
254 		} else {
255 			ACPI_DEBUG_PRINT((ACPI_DB_INFO,
256 					  "Null Handle with relative pathname [%s]",
257 					  pathname));
258 		}
259 
260 		status = AE_BAD_PARAMETER;
261 	} else {
262 		/* We have a namespace a node and a possible relative path */
263 
264 		status = acpi_ns_evaluate(info);
265 	}
266 
267 	/*
268 	 * If we are expecting a return value, and all went well above,
269 	 * copy the return value to an external object.
270 	 */
271 	if (return_buffer) {
272 		if (!info->return_object) {
273 			return_buffer->length = 0;
274 		} else {
275 			if (ACPI_GET_DESCRIPTOR_TYPE(info->return_object) ==
276 			    ACPI_DESC_TYPE_NAMED) {
277 				/*
278 				 * If we received a NS Node as a return object, this means that
279 				 * the object we are evaluating has nothing interesting to
280 				 * return (such as a mutex, etc.)  We return an error because
281 				 * these types are essentially unsupported by this interface.
282 				 * We don't check up front because this makes it easier to add
283 				 * support for various types at a later date if necessary.
284 				 */
285 				status = AE_TYPE;
286 				info->return_object = NULL;	/* No need to delete a NS Node */
287 				return_buffer->length = 0;
288 			}
289 
290 			if (ACPI_SUCCESS(status)) {
291 
292 				/* Dereference Index and ref_of references */
293 
294 				acpi_ns_resolve_references(info);
295 
296 				/* Get the size of the returned object */
297 
298 				status =
299 				    acpi_ut_get_object_size(info->return_object,
300 							    &buffer_space_needed);
301 				if (ACPI_SUCCESS(status)) {
302 
303 					/* Validate/Allocate/Clear caller buffer */
304 
305 					status =
306 					    acpi_ut_initialize_buffer
307 					    (return_buffer,
308 					     buffer_space_needed);
309 					if (ACPI_FAILURE(status)) {
310 						/*
311 						 * Caller's buffer is too small or a new one can't
312 						 * be allocated
313 						 */
314 						ACPI_DEBUG_PRINT((ACPI_DB_INFO,
315 								  "Needed buffer size %X, %s\n",
316 								  (u32)
317 								  buffer_space_needed,
318 								  acpi_format_exception
319 								  (status)));
320 					} else {
321 						/* We have enough space for the object, build it */
322 
323 						status =
324 						    acpi_ut_copy_iobject_to_eobject
325 						    (info->return_object,
326 						     return_buffer);
327 					}
328 				}
329 			}
330 		}
331 	}
332 
333 	if (info->return_object) {
334 		/*
335 		 * Delete the internal return object. NOTE: Interpreter must be
336 		 * locked to avoid race condition.
337 		 */
338 		acpi_ex_enter_interpreter();
339 
340 		/* Remove one reference on the return object (should delete it) */
341 
342 		acpi_ut_remove_reference(info->return_object);
343 		acpi_ex_exit_interpreter();
344 	}
345 
346       cleanup:
347 
348 	/* Free the input parameter list (if we created one) */
349 
350 	if (info->parameters) {
351 
352 		/* Free the allocated parameter block */
353 
354 		acpi_ut_delete_internal_object_list(info->parameters);
355 	}
356 
357 	ACPI_FREE(info);
358 	return_ACPI_STATUS(status);
359 }
360 
361 ACPI_EXPORT_SYMBOL(acpi_evaluate_object)
362 
363 /*******************************************************************************
364  *
365  * FUNCTION:    acpi_ns_resolve_references
366  *
367  * PARAMETERS:  info                    - Evaluation info block
368  *
369  * RETURN:      Info->return_object is replaced with the dereferenced object
370  *
371  * DESCRIPTION: Dereference certain reference objects. Called before an
372  *              internal return object is converted to an external union acpi_object.
373  *
374  * Performs an automatic dereference of Index and ref_of reference objects.
375  * These reference objects are not supported by the union acpi_object, so this is a
376  * last resort effort to return something useful. Also, provides compatibility
377  * with other ACPI implementations.
378  *
379  * NOTE: does not handle references within returned package objects or nested
380  * references, but this support could be added later if found to be necessary.
381  *
382  ******************************************************************************/
383 static void acpi_ns_resolve_references(struct acpi_evaluate_info *info)
384 {
385 	union acpi_operand_object *obj_desc = NULL;
386 	struct acpi_namespace_node *node;
387 
388 	/* We are interested in reference objects only */
389 
390 	if ((info->return_object)->common.type != ACPI_TYPE_LOCAL_REFERENCE) {
391 		return;
392 	}
393 
394 	/*
395 	 * Two types of references are supported - those created by Index and
396 	 * ref_of operators. A name reference (AML_NAMEPATH_OP) can be converted
397 	 * to an union acpi_object, so it is not dereferenced here. A ddb_handle
398 	 * (AML_LOAD_OP) cannot be dereferenced, nor can it be converted to
399 	 * an union acpi_object.
400 	 */
401 	switch (info->return_object->reference.class) {
402 	case ACPI_REFCLASS_INDEX:
403 
404 		obj_desc = *(info->return_object->reference.where);
405 		break;
406 
407 	case ACPI_REFCLASS_REFOF:
408 
409 		node = info->return_object->reference.object;
410 		if (node) {
411 			obj_desc = node->object;
412 		}
413 		break;
414 
415 	default:
416 		return;
417 	}
418 
419 	/* Replace the existing reference object */
420 
421 	if (obj_desc) {
422 		acpi_ut_add_reference(obj_desc);
423 		acpi_ut_remove_reference(info->return_object);
424 		info->return_object = obj_desc;
425 	}
426 
427 	return;
428 }
429 
430 /*******************************************************************************
431  *
432  * FUNCTION:    acpi_walk_namespace
433  *
434  * PARAMETERS:  type                - acpi_object_type to search for
435  *              start_object        - Handle in namespace where search begins
436  *              max_depth           - Depth to which search is to reach
437  *              pre_order_visit     - Called during tree pre-order visit
438  *                                    when an object of "Type" is found
439  *              post_order_visit    - Called during tree post-order visit
440  *                                    when an object of "Type" is found
441  *              context             - Passed to user function(s) above
442  *              return_value        - Location where return value of
443  *                                    user_function is put if terminated early
444  *
445  * RETURNS      Return value from the user_function if terminated early.
446  *              Otherwise, returns NULL.
447  *
448  * DESCRIPTION: Performs a modified depth-first walk of the namespace tree,
449  *              starting (and ending) at the object specified by start_handle.
450  *              The callback function is called whenever an object that matches
451  *              the type parameter is found. If the callback function returns
452  *              a non-zero value, the search is terminated immediately and this
453  *              value is returned to the caller.
454  *
455  *              The point of this procedure is to provide a generic namespace
456  *              walk routine that can be called from multiple places to
457  *              provide multiple services; the callback function(s) can be
458  *              tailored to each task, whether it is a print function,
459  *              a compare function, etc.
460  *
461  ******************************************************************************/
462 
463 acpi_status
464 acpi_walk_namespace(acpi_object_type type,
465 		    acpi_handle start_object,
466 		    u32 max_depth,
467 		    acpi_walk_callback pre_order_visit,
468 		    acpi_walk_callback post_order_visit,
469 		    void *context, void **return_value)
470 {
471 	acpi_status status;
472 
473 	ACPI_FUNCTION_TRACE(acpi_walk_namespace);
474 
475 	/* Parameter validation */
476 
477 	if ((type > ACPI_TYPE_LOCAL_MAX) ||
478 	    (!max_depth) || (!pre_order_visit && !post_order_visit)) {
479 		return_ACPI_STATUS(AE_BAD_PARAMETER);
480 	}
481 
482 	/*
483 	 * Need to acquire the namespace reader lock to prevent interference
484 	 * with any concurrent table unloads (which causes the deletion of
485 	 * namespace objects). We cannot allow the deletion of a namespace node
486 	 * while the user function is using it. The exception to this are the
487 	 * nodes created and deleted during control method execution -- these
488 	 * nodes are marked as temporary nodes and are ignored by the namespace
489 	 * walk. Thus, control methods can be executed while holding the
490 	 * namespace deletion lock (and the user function can execute control
491 	 * methods.)
492 	 */
493 	status = acpi_ut_acquire_read_lock(&acpi_gbl_namespace_rw_lock);
494 	if (ACPI_FAILURE(status)) {
495 		return status;
496 	}
497 
498 	/*
499 	 * Lock the namespace around the walk. The namespace will be
500 	 * unlocked/locked around each call to the user function - since the user
501 	 * function must be allowed to make ACPICA calls itself (for example, it
502 	 * will typically execute control methods during device enumeration.)
503 	 */
504 	status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
505 	if (ACPI_FAILURE(status)) {
506 		goto unlock_and_exit;
507 	}
508 
509 	status = acpi_ns_walk_namespace(type, start_object, max_depth,
510 					ACPI_NS_WALK_UNLOCK, pre_order_visit,
511 					post_order_visit, context,
512 					return_value);
513 
514 	(void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
515 
516       unlock_and_exit:
517 	(void)acpi_ut_release_read_lock(&acpi_gbl_namespace_rw_lock);
518 	return_ACPI_STATUS(status);
519 }
520 
521 ACPI_EXPORT_SYMBOL(acpi_walk_namespace)
522 
523 /*******************************************************************************
524  *
525  * FUNCTION:    acpi_ns_get_device_callback
526  *
527  * PARAMETERS:  Callback from acpi_get_device
528  *
529  * RETURN:      Status
530  *
531  * DESCRIPTION: Takes callbacks from walk_namespace and filters out all non-
532  *              present devices, or if they specified a HID, it filters based
533  *              on that.
534  *
535  ******************************************************************************/
536 static acpi_status
537 acpi_ns_get_device_callback(acpi_handle obj_handle,
538 			    u32 nesting_level,
539 			    void *context, void **return_value)
540 {
541 	struct acpi_get_devices_info *info = context;
542 	acpi_status status;
543 	struct acpi_namespace_node *node;
544 	u32 flags;
545 	struct acpica_device_id *hid;
546 	struct acpica_device_id_list *cid;
547 	u32 i;
548 	u8 found;
549 	int no_match;
550 
551 	status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
552 	if (ACPI_FAILURE(status)) {
553 		return (status);
554 	}
555 
556 	node = acpi_ns_validate_handle(obj_handle);
557 	status = acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
558 	if (ACPI_FAILURE(status)) {
559 		return (status);
560 	}
561 
562 	if (!node) {
563 		return (AE_BAD_PARAMETER);
564 	}
565 
566 	/*
567 	 * First, filter based on the device HID and CID.
568 	 *
569 	 * 01/2010: For this case where a specific HID is requested, we don't
570 	 * want to run _STA until we have an actual HID match. Thus, we will
571 	 * not unnecessarily execute _STA on devices for which the caller
572 	 * doesn't care about. Previously, _STA was executed unconditionally
573 	 * on all devices found here.
574 	 *
575 	 * A side-effect of this change is that now we will continue to search
576 	 * for a matching HID even under device trees where the parent device
577 	 * would have returned a _STA that indicates it is not present or
578 	 * not functioning (thus aborting the search on that branch).
579 	 */
580 	if (info->hid != NULL) {
581 		status = acpi_ut_execute_HID(node, &hid);
582 		if (status == AE_NOT_FOUND) {
583 			return (AE_OK);
584 		} else if (ACPI_FAILURE(status)) {
585 			return (AE_CTRL_DEPTH);
586 		}
587 
588 		no_match = ACPI_STRCMP(hid->string, info->hid);
589 		ACPI_FREE(hid);
590 
591 		if (no_match) {
592 			/*
593 			 * HID does not match, attempt match within the
594 			 * list of Compatible IDs (CIDs)
595 			 */
596 			status = acpi_ut_execute_CID(node, &cid);
597 			if (status == AE_NOT_FOUND) {
598 				return (AE_OK);
599 			} else if (ACPI_FAILURE(status)) {
600 				return (AE_CTRL_DEPTH);
601 			}
602 
603 			/* Walk the CID list */
604 
605 			found = 0;
606 			for (i = 0; i < cid->count; i++) {
607 				if (ACPI_STRCMP(cid->ids[i].string, info->hid)
608 				    == 0) {
609 					found = 1;
610 					break;
611 				}
612 			}
613 			ACPI_FREE(cid);
614 			if (!found)
615 				return (AE_OK);
616 		}
617 	}
618 
619 	/* Run _STA to determine if device is present */
620 
621 	status = acpi_ut_execute_STA(node, &flags);
622 	if (ACPI_FAILURE(status)) {
623 		return (AE_CTRL_DEPTH);
624 	}
625 
626 	if (!(flags & ACPI_STA_DEVICE_PRESENT) &&
627 	    !(flags & ACPI_STA_DEVICE_FUNCTIONING)) {
628 		/*
629 		 * Don't examine the children of the device only when the
630 		 * device is neither present nor functional. See ACPI spec,
631 		 * description of _STA for more information.
632 		 */
633 		return (AE_CTRL_DEPTH);
634 	}
635 
636 	/* We have a valid device, invoke the user function */
637 
638 	status = info->user_function(obj_handle, nesting_level, info->context,
639 				     return_value);
640 	return (status);
641 }
642 
643 /*******************************************************************************
644  *
645  * FUNCTION:    acpi_get_devices
646  *
647  * PARAMETERS:  HID                 - HID to search for. Can be NULL.
648  *              user_function       - Called when a matching object is found
649  *              context             - Passed to user function
650  *              return_value        - Location where return value of
651  *                                    user_function is put if terminated early
652  *
653  * RETURNS      Return value from the user_function if terminated early.
654  *              Otherwise, returns NULL.
655  *
656  * DESCRIPTION: Performs a modified depth-first walk of the namespace tree,
657  *              starting (and ending) at the object specified by start_handle.
658  *              The user_function is called whenever an object of type
659  *              Device is found.  If the user function returns
660  *              a non-zero value, the search is terminated immediately and this
661  *              value is returned to the caller.
662  *
663  *              This is a wrapper for walk_namespace, but the callback performs
664  *              additional filtering. Please see acpi_ns_get_device_callback.
665  *
666  ******************************************************************************/
667 
668 acpi_status
669 acpi_get_devices(const char *HID,
670 		 acpi_walk_callback user_function,
671 		 void *context, void **return_value)
672 {
673 	acpi_status status;
674 	struct acpi_get_devices_info info;
675 
676 	ACPI_FUNCTION_TRACE(acpi_get_devices);
677 
678 	/* Parameter validation */
679 
680 	if (!user_function) {
681 		return_ACPI_STATUS(AE_BAD_PARAMETER);
682 	}
683 
684 	/*
685 	 * We're going to call their callback from OUR callback, so we need
686 	 * to know what it is, and their context parameter.
687 	 */
688 	info.hid = HID;
689 	info.context = context;
690 	info.user_function = user_function;
691 
692 	/*
693 	 * Lock the namespace around the walk.
694 	 * The namespace will be unlocked/locked around each call
695 	 * to the user function - since this function
696 	 * must be allowed to make Acpi calls itself.
697 	 */
698 	status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
699 	if (ACPI_FAILURE(status)) {
700 		return_ACPI_STATUS(status);
701 	}
702 
703 	status = acpi_ns_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
704 					ACPI_UINT32_MAX, ACPI_NS_WALK_UNLOCK,
705 					acpi_ns_get_device_callback, NULL,
706 					&info, return_value);
707 
708 	(void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
709 	return_ACPI_STATUS(status);
710 }
711 
712 ACPI_EXPORT_SYMBOL(acpi_get_devices)
713 
714 /*******************************************************************************
715  *
716  * FUNCTION:    acpi_attach_data
717  *
718  * PARAMETERS:  obj_handle          - Namespace node
719  *              handler             - Handler for this attachment
720  *              data                - Pointer to data to be attached
721  *
722  * RETURN:      Status
723  *
724  * DESCRIPTION: Attach arbitrary data and handler to a namespace node.
725  *
726  ******************************************************************************/
727 acpi_status
728 acpi_attach_data(acpi_handle obj_handle,
729 		 acpi_object_handler handler, void *data)
730 {
731 	struct acpi_namespace_node *node;
732 	acpi_status status;
733 
734 	/* Parameter validation */
735 
736 	if (!obj_handle || !handler || !data) {
737 		return (AE_BAD_PARAMETER);
738 	}
739 
740 	status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
741 	if (ACPI_FAILURE(status)) {
742 		return (status);
743 	}
744 
745 	/* Convert and validate the handle */
746 
747 	node = acpi_ns_validate_handle(obj_handle);
748 	if (!node) {
749 		status = AE_BAD_PARAMETER;
750 		goto unlock_and_exit;
751 	}
752 
753 	status = acpi_ns_attach_data(node, handler, data);
754 
755       unlock_and_exit:
756 	(void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
757 	return (status);
758 }
759 
760 ACPI_EXPORT_SYMBOL(acpi_attach_data)
761 
762 /*******************************************************************************
763  *
764  * FUNCTION:    acpi_detach_data
765  *
766  * PARAMETERS:  obj_handle          - Namespace node handle
767  *              handler             - Handler used in call to acpi_attach_data
768  *
769  * RETURN:      Status
770  *
771  * DESCRIPTION: Remove data that was previously attached to a node.
772  *
773  ******************************************************************************/
774 acpi_status
775 acpi_detach_data(acpi_handle obj_handle, acpi_object_handler handler)
776 {
777 	struct acpi_namespace_node *node;
778 	acpi_status status;
779 
780 	/* Parameter validation */
781 
782 	if (!obj_handle || !handler) {
783 		return (AE_BAD_PARAMETER);
784 	}
785 
786 	status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
787 	if (ACPI_FAILURE(status)) {
788 		return (status);
789 	}
790 
791 	/* Convert and validate the handle */
792 
793 	node = acpi_ns_validate_handle(obj_handle);
794 	if (!node) {
795 		status = AE_BAD_PARAMETER;
796 		goto unlock_and_exit;
797 	}
798 
799 	status = acpi_ns_detach_data(node, handler);
800 
801       unlock_and_exit:
802 	(void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
803 	return (status);
804 }
805 
806 ACPI_EXPORT_SYMBOL(acpi_detach_data)
807 
808 /*******************************************************************************
809  *
810  * FUNCTION:    acpi_get_data
811  *
812  * PARAMETERS:  obj_handle          - Namespace node
813  *              handler             - Handler used in call to attach_data
814  *              data                - Where the data is returned
815  *
816  * RETURN:      Status
817  *
818  * DESCRIPTION: Retrieve data that was previously attached to a namespace node.
819  *
820  ******************************************************************************/
821 acpi_status
822 acpi_get_data(acpi_handle obj_handle, acpi_object_handler handler, void **data)
823 {
824 	struct acpi_namespace_node *node;
825 	acpi_status status;
826 
827 	/* Parameter validation */
828 
829 	if (!obj_handle || !handler || !data) {
830 		return (AE_BAD_PARAMETER);
831 	}
832 
833 	status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
834 	if (ACPI_FAILURE(status)) {
835 		return (status);
836 	}
837 
838 	/* Convert and validate the handle */
839 
840 	node = acpi_ns_validate_handle(obj_handle);
841 	if (!node) {
842 		status = AE_BAD_PARAMETER;
843 		goto unlock_and_exit;
844 	}
845 
846 	status = acpi_ns_get_attached_data(node, handler, data);
847 
848       unlock_and_exit:
849 	(void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
850 	return (status);
851 }
852 
853 ACPI_EXPORT_SYMBOL(acpi_get_data)
854