1// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
2/******************************************************************************
3 *
4 * Module Name: nswalk - Functions for walking the ACPI namespace
5 *
6 * Copyright (C) 2000 - 2023, Intel Corp.
7 *
8 *****************************************************************************/
9
10#include <acpi/acpi.h>
11#include "accommon.h"
12#include "acnamesp.h"
13
14#define _COMPONENT          ACPI_NAMESPACE
15ACPI_MODULE_NAME("nswalk")
16
17/*******************************************************************************
18 *
19 * FUNCTION:    acpi_ns_get_next_node
20 *
21 * PARAMETERS:  parent_node         - Parent node whose children we are
22 *                                    getting
23 *              child_node          - Previous child that was found.
24 *                                    The NEXT child will be returned
25 *
26 * RETURN:      struct acpi_namespace_node - Pointer to the NEXT child or NULL if
27 *                                    none is found.
28 *
29 * DESCRIPTION: Return the next peer node within the namespace. If Handle
30 *              is valid, Scope is ignored. Otherwise, the first node
31 *              within Scope is returned.
32 *
33 ******************************************************************************/
34struct acpi_namespace_node *acpi_ns_get_next_node(struct acpi_namespace_node
35						  *parent_node,
36						  struct acpi_namespace_node
37						  *child_node)
38{
39	ACPI_FUNCTION_ENTRY();
40
41	if (!child_node) {
42
43		/* It's really the parent's _scope_ that we want */
44
45		return (parent_node->child);
46	}
47
48	/* Otherwise just return the next peer */
49
50	return (child_node->peer);
51}
52
53/*******************************************************************************
54 *
55 * FUNCTION:    acpi_ns_get_next_node_typed
56 *
57 * PARAMETERS:  type                - Type of node to be searched for
58 *              parent_node         - Parent node whose children we are
59 *                                    getting
60 *              child_node          - Previous child that was found.
61 *                                    The NEXT child will be returned
62 *
63 * RETURN:      struct acpi_namespace_node - Pointer to the NEXT child or NULL if
64 *                                    none is found.
65 *
66 * DESCRIPTION: Return the next peer node within the namespace. If Handle
67 *              is valid, Scope is ignored. Otherwise, the first node
68 *              within Scope is returned.
69 *
70 ******************************************************************************/
71
72struct acpi_namespace_node *acpi_ns_get_next_node_typed(acpi_object_type type,
73							struct
74							acpi_namespace_node
75							*parent_node,
76							struct
77							acpi_namespace_node
78							*child_node)
79{
80	struct acpi_namespace_node *next_node = NULL;
81
82	ACPI_FUNCTION_ENTRY();
83
84	next_node = acpi_ns_get_next_node(parent_node, child_node);
85
86
87	/* If any type is OK, we are done */
88
89	if (type == ACPI_TYPE_ANY) {
90
91		/* next_node is NULL if we are at the end-of-list */
92
93		return (next_node);
94	}
95
96	/* Must search for the node -- but within this scope only */
97
98	while (next_node) {
99
100		/* If type matches, we are done */
101
102		if (next_node->type == type) {
103			return (next_node);
104		}
105
106		/* Otherwise, move on to the next peer node */
107
108		next_node = next_node->peer;
109	}
110
111	/* Not found */
112
113	return (NULL);
114}
115
116/*******************************************************************************
117 *
118 * FUNCTION:    acpi_ns_walk_namespace
119 *
120 * PARAMETERS:  type                - acpi_object_type to search for
121 *              start_node          - Handle in namespace where search begins
122 *              max_depth           - Depth to which search is to reach
123 *              flags               - Whether to unlock the NS before invoking
124 *                                    the callback routine
125 *              descending_callback - Called during tree descent
126 *                                    when an object of "Type" is found
127 *              ascending_callback  - Called during tree ascent
128 *                                    when an object of "Type" is found
129 *              context             - Passed to user function(s) above
130 *              return_value        - from the user_function if terminated
131 *                                    early. Otherwise, returns NULL.
132 * RETURNS:     Status
133 *
134 * DESCRIPTION: Performs a modified depth-first walk of the namespace tree,
135 *              starting (and ending) at the node specified by start_handle.
136 *              The callback function is called whenever a node that matches
137 *              the type parameter is found. If the callback function returns
138 *              a non-zero value, the search is terminated immediately and
139 *              this value is returned to the caller.
140 *
141 *              The point of this procedure is to provide a generic namespace
142 *              walk routine that can be called from multiple places to
143 *              provide multiple services; the callback function(s) can be
144 *              tailored to each task, whether it is a print function,
145 *              a compare function, etc.
146 *
147 ******************************************************************************/
148
149acpi_status
150acpi_ns_walk_namespace(acpi_object_type type,
151		       acpi_handle start_node,
152		       u32 max_depth,
153		       u32 flags,
154		       acpi_walk_callback descending_callback,
155		       acpi_walk_callback ascending_callback,
156		       void *context, void **return_value)
157{
158	acpi_status status;
159	acpi_status mutex_status;
160	struct acpi_namespace_node *child_node;
161	struct acpi_namespace_node *parent_node;
162	acpi_object_type child_type;
163	u32 level;
164	u8 node_previously_visited = FALSE;
165
166	ACPI_FUNCTION_TRACE(ns_walk_namespace);
167
168	/* Special case for the namespace Root Node */
169
170	if (start_node == ACPI_ROOT_OBJECT) {
171		start_node = acpi_gbl_root_node;
172		if (!start_node) {
173			return_ACPI_STATUS(AE_NO_NAMESPACE);
174		}
175	}
176
177	/* Null child means "get first node" */
178
179	parent_node = start_node;
180	child_node = acpi_ns_get_next_node(parent_node, NULL);
181	child_type = ACPI_TYPE_ANY;
182	level = 1;
183
184	/*
185	 * Traverse the tree of nodes until we bubble back up to where we
186	 * started. When Level is zero, the loop is done because we have
187	 * bubbled up to (and passed) the original parent handle (start_entry)
188	 */
189	while (level > 0 && child_node) {
190		status = AE_OK;
191
192		/* Found next child, get the type if we are not searching for ANY */
193
194		if (type != ACPI_TYPE_ANY) {
195			child_type = child_node->type;
196		}
197
198		/*
199		 * Ignore all temporary namespace nodes (created during control
200		 * method execution) unless told otherwise. These temporary nodes
201		 * can cause a race condition because they can be deleted during
202		 * the execution of the user function (if the namespace is
203		 * unlocked before invocation of the user function.) Only the
204		 * debugger namespace dump will examine the temporary nodes.
205		 */
206		if ((child_node->flags & ANOBJ_TEMPORARY) &&
207		    !(flags & ACPI_NS_WALK_TEMP_NODES)) {
208			status = AE_CTRL_DEPTH;
209		}
210
211		/* Type must match requested type */
212
213		else if (child_type == type) {
214			/*
215			 * Found a matching node, invoke the user callback function.
216			 * Unlock the namespace if flag is set.
217			 */
218			if (flags & ACPI_NS_WALK_UNLOCK) {
219				mutex_status =
220				    acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
221				if (ACPI_FAILURE(mutex_status)) {
222					return_ACPI_STATUS(mutex_status);
223				}
224			}
225
226			/*
227			 * Invoke the user function, either descending, ascending,
228			 * or both.
229			 */
230			if (!node_previously_visited) {
231				if (descending_callback) {
232					status =
233					    descending_callback(child_node,
234								level, context,
235								return_value);
236				}
237			} else {
238				if (ascending_callback) {
239					status =
240					    ascending_callback(child_node,
241							       level, context,
242							       return_value);
243				}
244			}
245
246			if (flags & ACPI_NS_WALK_UNLOCK) {
247				mutex_status =
248				    acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
249				if (ACPI_FAILURE(mutex_status)) {
250					return_ACPI_STATUS(mutex_status);
251				}
252			}
253
254			switch (status) {
255			case AE_OK:
256			case AE_CTRL_DEPTH:
257
258				/* Just keep going */
259				break;
260
261			case AE_CTRL_TERMINATE:
262
263				/* Exit now, with OK status */
264
265				return_ACPI_STATUS(AE_OK);
266
267			default:
268
269				/* All others are valid exceptions */
270
271				return_ACPI_STATUS(status);
272			}
273		}
274
275		/*
276		 * Depth first search: Attempt to go down another level in the
277		 * namespace if we are allowed to. Don't go any further if we have
278		 * reached the caller specified maximum depth or if the user
279		 * function has specified that the maximum depth has been reached.
280		 */
281		if (!node_previously_visited &&
282		    (level < max_depth) && (status != AE_CTRL_DEPTH)) {
283			if (child_node->child) {
284
285				/* There is at least one child of this node, visit it */
286
287				level++;
288				parent_node = child_node;
289				child_node =
290				    acpi_ns_get_next_node(parent_node, NULL);
291				continue;
292			}
293		}
294
295		/* No more children, re-visit this node */
296
297		if (!node_previously_visited) {
298			node_previously_visited = TRUE;
299			continue;
300		}
301
302		/* No more children, visit peers */
303
304		child_node = acpi_ns_get_next_node(parent_node, child_node);
305		if (child_node) {
306			node_previously_visited = FALSE;
307		}
308
309		/* No peers, re-visit parent */
310
311		else {
312			/*
313			 * No more children of this node (acpi_ns_get_next_node failed), go
314			 * back upwards in the namespace tree to the node's parent.
315			 */
316			level--;
317			child_node = parent_node;
318			parent_node = parent_node->parent;
319
320			node_previously_visited = TRUE;
321		}
322	}
323
324	/* Complete walk, not terminated by user function */
325
326	return_ACPI_STATUS(AE_OK);
327}
328