xref: /openbmc/linux/drivers/acpi/acpica/nswalk.c (revision 4da722ca)
1 /******************************************************************************
2  *
3  * Module Name: nswalk - Functions for walking the ACPI namespace
4  *
5  *****************************************************************************/
6 
7 /*
8  * Copyright (C) 2000 - 2017, 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 #include <acpi/acpi.h>
45 #include "accommon.h"
46 #include "acnamesp.h"
47 
48 #define _COMPONENT          ACPI_NAMESPACE
49 ACPI_MODULE_NAME("nswalk")
50 
51 /*******************************************************************************
52  *
53  * FUNCTION:    acpi_ns_get_next_node
54  *
55  * PARAMETERS:  parent_node         - Parent node whose children we are
56  *                                    getting
57  *              child_node          - Previous child that was found.
58  *                                    The NEXT child will be returned
59  *
60  * RETURN:      struct acpi_namespace_node - Pointer to the NEXT child or NULL if
61  *                                    none is found.
62  *
63  * DESCRIPTION: Return the next peer node within the namespace. If Handle
64  *              is valid, Scope is ignored. Otherwise, the first node
65  *              within Scope is returned.
66  *
67  ******************************************************************************/
68 struct acpi_namespace_node *acpi_ns_get_next_node(struct acpi_namespace_node
69 						  *parent_node,
70 						  struct acpi_namespace_node
71 						  *child_node)
72 {
73 	ACPI_FUNCTION_ENTRY();
74 
75 	if (!child_node) {
76 
77 		/* It's really the parent's _scope_ that we want */
78 
79 		return (parent_node->child);
80 	}
81 
82 	/* Otherwise just return the next peer */
83 
84 	return (child_node->peer);
85 }
86 
87 /*******************************************************************************
88  *
89  * FUNCTION:    acpi_ns_get_next_node_typed
90  *
91  * PARAMETERS:  type                - Type of node to be searched for
92  *              parent_node         - Parent node whose children we are
93  *                                    getting
94  *              child_node          - Previous child that was found.
95  *                                    The NEXT child will be returned
96  *
97  * RETURN:      struct acpi_namespace_node - Pointer to the NEXT child or NULL if
98  *                                    none is found.
99  *
100  * DESCRIPTION: Return the next peer node within the namespace. If Handle
101  *              is valid, Scope is ignored. Otherwise, the first node
102  *              within Scope is returned.
103  *
104  ******************************************************************************/
105 
106 struct acpi_namespace_node *acpi_ns_get_next_node_typed(acpi_object_type type,
107 							struct
108 							acpi_namespace_node
109 							*parent_node,
110 							struct
111 							acpi_namespace_node
112 							*child_node)
113 {
114 	struct acpi_namespace_node *next_node = NULL;
115 
116 	ACPI_FUNCTION_ENTRY();
117 
118 	next_node = acpi_ns_get_next_node(parent_node, child_node);
119 
120 
121 	/* If any type is OK, we are done */
122 
123 	if (type == ACPI_TYPE_ANY) {
124 
125 		/* next_node is NULL if we are at the end-of-list */
126 
127 		return (next_node);
128 	}
129 
130 	/* Must search for the node -- but within this scope only */
131 
132 	while (next_node) {
133 
134 		/* If type matches, we are done */
135 
136 		if (next_node->type == type) {
137 			return (next_node);
138 		}
139 
140 		/* Otherwise, move on to the next peer node */
141 
142 		next_node = next_node->peer;
143 	}
144 
145 	/* Not found */
146 
147 	return (NULL);
148 }
149 
150 /*******************************************************************************
151  *
152  * FUNCTION:    acpi_ns_walk_namespace
153  *
154  * PARAMETERS:  type                - acpi_object_type to search for
155  *              start_node          - Handle in namespace where search begins
156  *              max_depth           - Depth to which search is to reach
157  *              flags               - Whether to unlock the NS before invoking
158  *                                    the callback routine
159  *              descending_callback - Called during tree descent
160  *                                    when an object of "Type" is found
161  *              ascending_callback  - Called during tree ascent
162  *                                    when an object of "Type" is found
163  *              context             - Passed to user function(s) above
164  *              return_value        - from the user_function if terminated
165  *                                    early. Otherwise, returns NULL.
166  * RETURNS:     Status
167  *
168  * DESCRIPTION: Performs a modified depth-first walk of the namespace tree,
169  *              starting (and ending) at the node specified by start_handle.
170  *              The callback function is called whenever a node that matches
171  *              the type parameter is found. If the callback function returns
172  *              a non-zero value, the search is terminated immediately and
173  *              this value is returned to the caller.
174  *
175  *              The point of this procedure is to provide a generic namespace
176  *              walk routine that can be called from multiple places to
177  *              provide multiple services; the callback function(s) can be
178  *              tailored to each task, whether it is a print function,
179  *              a compare function, etc.
180  *
181  ******************************************************************************/
182 
183 acpi_status
184 acpi_ns_walk_namespace(acpi_object_type type,
185 		       acpi_handle start_node,
186 		       u32 max_depth,
187 		       u32 flags,
188 		       acpi_walk_callback descending_callback,
189 		       acpi_walk_callback ascending_callback,
190 		       void *context, void **return_value)
191 {
192 	acpi_status status;
193 	acpi_status mutex_status;
194 	struct acpi_namespace_node *child_node;
195 	struct acpi_namespace_node *parent_node;
196 	acpi_object_type child_type;
197 	u32 level;
198 	u8 node_previously_visited = FALSE;
199 
200 	ACPI_FUNCTION_TRACE(ns_walk_namespace);
201 
202 	/* Special case for the namespace Root Node */
203 
204 	if (start_node == ACPI_ROOT_OBJECT) {
205 		start_node = acpi_gbl_root_node;
206 	}
207 
208 	/* Null child means "get first node" */
209 
210 	parent_node = start_node;
211 	child_node = acpi_ns_get_next_node(parent_node, NULL);
212 	child_type = ACPI_TYPE_ANY;
213 	level = 1;
214 
215 	/*
216 	 * Traverse the tree of nodes until we bubble back up to where we
217 	 * started. When Level is zero, the loop is done because we have
218 	 * bubbled up to (and passed) the original parent handle (start_entry)
219 	 */
220 	while (level > 0 && child_node) {
221 		status = AE_OK;
222 
223 		/* Found next child, get the type if we are not searching for ANY */
224 
225 		if (type != ACPI_TYPE_ANY) {
226 			child_type = child_node->type;
227 		}
228 
229 		/*
230 		 * Ignore all temporary namespace nodes (created during control
231 		 * method execution) unless told otherwise. These temporary nodes
232 		 * can cause a race condition because they can be deleted during
233 		 * the execution of the user function (if the namespace is
234 		 * unlocked before invocation of the user function.) Only the
235 		 * debugger namespace dump will examine the temporary nodes.
236 		 */
237 		if ((child_node->flags & ANOBJ_TEMPORARY) &&
238 		    !(flags & ACPI_NS_WALK_TEMP_NODES)) {
239 			status = AE_CTRL_DEPTH;
240 		}
241 
242 		/* Type must match requested type */
243 
244 		else if (child_type == type) {
245 			/*
246 			 * Found a matching node, invoke the user callback function.
247 			 * Unlock the namespace if flag is set.
248 			 */
249 			if (flags & ACPI_NS_WALK_UNLOCK) {
250 				mutex_status =
251 				    acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
252 				if (ACPI_FAILURE(mutex_status)) {
253 					return_ACPI_STATUS(mutex_status);
254 				}
255 			}
256 
257 			/*
258 			 * Invoke the user function, either descending, ascending,
259 			 * or both.
260 			 */
261 			if (!node_previously_visited) {
262 				if (descending_callback) {
263 					status =
264 					    descending_callback(child_node,
265 								level, context,
266 								return_value);
267 				}
268 			} else {
269 				if (ascending_callback) {
270 					status =
271 					    ascending_callback(child_node,
272 							       level, context,
273 							       return_value);
274 				}
275 			}
276 
277 			if (flags & ACPI_NS_WALK_UNLOCK) {
278 				mutex_status =
279 				    acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
280 				if (ACPI_FAILURE(mutex_status)) {
281 					return_ACPI_STATUS(mutex_status);
282 				}
283 			}
284 
285 			switch (status) {
286 			case AE_OK:
287 			case AE_CTRL_DEPTH:
288 
289 				/* Just keep going */
290 				break;
291 
292 			case AE_CTRL_TERMINATE:
293 
294 				/* Exit now, with OK status */
295 
296 				return_ACPI_STATUS(AE_OK);
297 
298 			default:
299 
300 				/* All others are valid exceptions */
301 
302 				return_ACPI_STATUS(status);
303 			}
304 		}
305 
306 		/*
307 		 * Depth first search: Attempt to go down another level in the
308 		 * namespace if we are allowed to. Don't go any further if we have
309 		 * reached the caller specified maximum depth or if the user
310 		 * function has specified that the maximum depth has been reached.
311 		 */
312 		if (!node_previously_visited &&
313 		    (level < max_depth) && (status != AE_CTRL_DEPTH)) {
314 			if (child_node->child) {
315 
316 				/* There is at least one child of this node, visit it */
317 
318 				level++;
319 				parent_node = child_node;
320 				child_node =
321 				    acpi_ns_get_next_node(parent_node, NULL);
322 				continue;
323 			}
324 		}
325 
326 		/* No more children, re-visit this node */
327 
328 		if (!node_previously_visited) {
329 			node_previously_visited = TRUE;
330 			continue;
331 		}
332 
333 		/* No more children, visit peers */
334 
335 		child_node = acpi_ns_get_next_node(parent_node, child_node);
336 		if (child_node) {
337 			node_previously_visited = FALSE;
338 		}
339 
340 		/* No peers, re-visit parent */
341 
342 		else {
343 			/*
344 			 * No more children of this node (acpi_ns_get_next_node failed), go
345 			 * back upwards in the namespace tree to the node's parent.
346 			 */
347 			level--;
348 			child_node = parent_node;
349 			parent_node = parent_node->parent;
350 
351 			node_previously_visited = TRUE;
352 		}
353 	}
354 
355 	/* Complete walk, not terminated by user function */
356 
357 	return_ACPI_STATUS(AE_OK);
358 }
359