drivers/acpi/namespace/nswalk.c

   1 /******************************************************************************
   2  *
   3  * Module Name: nswalk - Functions for walking the ACPI namespace
   4  *
   5  *****************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2007, R. Byron Moore
   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 <acpi/acnamesp.h>
  46
  47 #define _COMPONENT          ACPI_NAMESPACE
  48 ACPI_MODULE_NAME("nswalk")
  49
  50 /*******************************************************************************
  51  *
  52  * FUNCTION:    acpi_ns_get_next_node
  53  *
  54  * PARAMETERS:  Type                - Type of node to be searched for
  55  *              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(acpi_object_type type, struct acpi_namespace_node
  69                                                   *parent_node, struct acpi_namespace_node
  70                                                   *child_node)
  71 {
  72         struct acpi_namespace_node *next_node = NULL;
  73
  74         ACPI_FUNCTION_ENTRY();
  75
  76         if (!child_node) {
  77
  78                 /* It's really the parent's _scope_ that we want */
  79
  80                 if (parent_node->child) {
  81                         next_node = parent_node->child;
  82                 }
  83         }
  84
  85         else {
  86                 /* Start search at the NEXT node */
  87
  88                 next_node = acpi_ns_get_next_valid_node(child_node);
  89         }
  90
  91         /* If any type is OK, we are done */
  92
  93         if (type == ACPI_TYPE_ANY) {
  94
  95                 /* next_node is NULL if we are at the end-of-list */
  96
  97                 return (next_node);
  98         }
  99
 100         /* Must search for the node -- but within this scope only */
 101
 102         while (next_node) {
 103
 104                 /* If type matches, we are done */
 105
 106                 if (next_node->type == type) {
 107                         return (next_node);
 108                 }
 109
 110                 /* Otherwise, move on to the next node */
 111
 112                 next_node = acpi_ns_get_next_valid_node(next_node);
 113         }
 114
 115         /* Not found */
 116
 117         return (NULL);
 118 }
 119
 120 /*******************************************************************************
 121  *
 122  * FUNCTION:    acpi_ns_walk_namespace
 123  *
 124  * PARAMETERS:  Type                - acpi_object_type to search for
 125  *              start_node          - Handle in namespace where search begins
 126  *              max_depth           - Depth to which search is to reach
 127  *              Flags               - Whether to unlock the NS before invoking
 128  *                                    the callback routine
 129  *              user_function       - Called when an object of "Type" is found
 130  *              Context             - Passed to user function
 131  *              return_value        - from the user_function if terminated early.
 132  *                                    Otherwise, returns NULL.
 133  * RETURNS:     Status
 134  *
 135  * DESCRIPTION: Performs a modified depth-first walk of the namespace tree,
 136  *              starting (and ending) at the node specified by start_handle.
 137  *              The user_function is called whenever a node that matches
 138  *              the type parameter is found.  If the user function returns
 139  *              a non-zero value, the search is terminated immediately and this
 140  *              value is returned to the caller.
 141  *
 142  *              The point of this procedure is to provide a generic namespace
 143  *              walk routine that can be called from multiple places to
 144  *              provide multiple services;  the User Function can be tailored
 145  *              to each task, whether it is a print function, a compare
 146  *              function, etc.
 147  *
 148  ******************************************************************************/
 149
 150 acpi_status
 151 acpi_ns_walk_namespace(acpi_object_type type,
 152                        acpi_handle start_node,
 153                        u32 max_depth,
 154                        u32 flags,
 155                        acpi_walk_callback user_function,
 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
 165         ACPI_FUNCTION_TRACE(ns_walk_namespace);
 166
 167         /* Special case for the namespace Root Node */
 168
 169         if (start_node == ACPI_ROOT_OBJECT) {
 170                 start_node = acpi_gbl_root_node;
 171         }
 172
 173         /* Null child means "get first node" */
 174
 175         parent_node = start_node;
 176         child_node = NULL;
 177         child_type = ACPI_TYPE_ANY;
 178         level = 1;
 179
 180         /*
 181          * Traverse the tree of nodes until we bubble back up to where we
 182          * started. When Level is zero, the loop is done because we have
 183          * bubbled up to (and passed) the original parent handle (start_entry)
 184          */
 185         while (level > 0) {
 186
 187                 /* Get the next node in this scope.  Null if not found */
 188
 189                 status = AE_OK;
 190                 child_node =
 191                     acpi_ns_get_next_node(ACPI_TYPE_ANY, parent_node,
 192                                           child_node);
 193                 if (child_node) {
 194
 195                         /* Found next child, get the type if we are not searching for ANY */
 196
 197                         if (type != ACPI_TYPE_ANY) {
 198                                 child_type = child_node->type;
 199                         }
 200
 201                         /*
 202                          * Ignore all temporary namespace nodes (created during control
 203                          * method execution) unless told otherwise. These temporary nodes
 204                          * can cause a race condition because they can be deleted during the
 205                          * execution of the user function (if the namespace is unlocked before
 206                          * invocation of the user function.) Only the debugger namespace dump
 207                          * will examine the temporary nodes.
 208                          */
 209                         if ((child_node->flags & ANOBJ_TEMPORARY) &&
 210                             !(flags & ACPI_NS_WALK_TEMP_NODES)) {
 211                                 status = AE_CTRL_DEPTH;
 212                         }
 213
 214                         /* Type must match requested type */
 215
 216                         else if (child_type == type) {
 217                                 /*
 218                                  * Found a matching node, invoke the user callback function.
 219                                  * Unlock the namespace if flag is set.
 220                                  */
 221                                 if (flags & ACPI_NS_WALK_UNLOCK) {
 222                                         mutex_status =
 223                                             acpi_ut_release_mutex
 224                                             (ACPI_MTX_NAMESPACE);
 225                                         if (ACPI_FAILURE(mutex_status)) {
 226                                                 return_ACPI_STATUS
 227                                                     (mutex_status);
 228                                         }
 229                                 }
 230
 231                                 status =
 232                                     user_function(child_node, level, context,
 233                                                   return_value);
 234
 235                                 if (flags & ACPI_NS_WALK_UNLOCK) {
 236                                         mutex_status =
 237                                             acpi_ut_acquire_mutex
 238                                             (ACPI_MTX_NAMESPACE);
 239                                         if (ACPI_FAILURE(mutex_status)) {
 240                                                 return_ACPI_STATUS
 241                                                     (mutex_status);
 242                                         }
 243                                 }
 244
 245                                 switch (status) {
 246                                 case AE_OK:
 247                                 case AE_CTRL_DEPTH:
 248
 249                                         /* Just keep going */
 250                                         break;
 251
 252                                 case AE_CTRL_TERMINATE:
 253
 254                                         /* Exit now, with OK status */
 255
 256                                         return_ACPI_STATUS(AE_OK);
 257
 258                                 default:
 259
 260                                         /* All others are valid exceptions */
 261
 262                                         return_ACPI_STATUS(status);
 263                                 }
 264                         }
 265
 266                         /*
 267                          * Depth first search: Attempt to go down another level in the
 268                          * namespace if we are allowed to.  Don't go any further if we have
 269                          * reached the caller specified maximum depth or if the user
 270                          * function has specified that the maximum depth has been reached.
 271                          */
 272                         if ((level < max_depth) && (status != AE_CTRL_DEPTH)) {
 273                                 if (acpi_ns_get_next_node
 274                                     (ACPI_TYPE_ANY, child_node, NULL)) {
 275
 276                                         /* There is at least one child of this node, visit it */
 277
 278                                         level++;
 279                                         parent_node = child_node;
 280                                         child_node = NULL;
 281                                 }
 282                         }
 283                 } else {
 284                         /*
 285                          * No more children of this node (acpi_ns_get_next_node failed), go
 286                          * back upwards in the namespace tree to the node's parent.
 287                          */
 288                         level--;
 289                         child_node = parent_node;
 290                         parent_node = acpi_ns_get_parent_node(parent_node);
 291                 }
 292         }
 293
 294         /* Complete walk, not terminated by user function */
 295
 296         return_ACPI_STATUS(AE_OK);
 297 }