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,
  69                                                   struct acpi_namespace_node
  70                                                   *parent_node,
  71                                                   struct acpi_namespace_node
  72                                                   *child_node)
  73 {
  74         struct acpi_namespace_node *next_node = NULL;
  75
  76         ACPI_FUNCTION_ENTRY();
  77
  78         if (!child_node) {
  79
  80                 /* It's really the parent's _scope_ that we want */
  81
  82                 if (parent_node->child) {
  83                         next_node = parent_node->child;
  84                 }
  85         }
  86
  87         else {
  88                 /* Start search at the NEXT node */
  89
  90                 next_node = acpi_ns_get_next_valid_node(child_node);
  91         }
  92
  93         /* If any type is OK, we are done */
  94
  95         if (type == ACPI_TYPE_ANY) {
  96
  97                 /* next_node is NULL if we are at the end-of-list */
  98
  99                 return (next_node);
 100         }
 101
 102         /* Must search for the node -- but within this scope only */
 103
 104         while (next_node) {
 105
 106                 /* If type matches, we are done */
 107
 108                 if (next_node->type == type) {
 109                         return (next_node);
 110                 }
 111
 112                 /* Otherwise, move on to the next node */
 113
 114                 next_node = acpi_ns_get_next_valid_node(next_node);
 115         }
 116
 117         /* Not found */
 118
 119         return (NULL);
 120 }
 121
 122 /*******************************************************************************
 123  *
 124  * FUNCTION:    acpi_ns_walk_namespace
 125  *
 126  * PARAMETERS:  Type                - acpi_object_type to search for
 127  *              start_node          - Handle in namespace where search begins
 128  *              max_depth           - Depth to which search is to reach
 129  *              Flags               - Whether to unlock the NS before invoking
 130  *                                    the callback routine
 131  *              user_function       - Called when an object of "Type" is found
 132  *              Context             - Passed to user function
 133  *              return_value        - from the user_function if terminated early.
 134  *                                    Otherwise, returns NULL.
 135  * RETURNS:     Status
 136  *
 137  * DESCRIPTION: Performs a modified depth-first walk of the namespace tree,
 138  *              starting (and ending) at the node specified by start_handle.
 139  *              The user_function is called whenever a node that matches
 140  *              the type parameter is found.  If the user function returns
 141  *              a non-zero value, the search is terminated immediately and this
 142  *              value is returned to the caller.
 143  *
 144  *              The point of this procedure is to provide a generic namespace
 145  *              walk routine that can be called from multiple places to
 146  *              provide multiple services;  the User Function can be tailored
 147  *              to each task, whether it is a print function, a compare
 148  *              function, etc.
 149  *
 150  ******************************************************************************/
 151
 152 acpi_status
 153 acpi_ns_walk_namespace(acpi_object_type type,
 154                        acpi_handle start_node,
 155                        u32 max_depth,
 156                        u32 flags,
 157                        acpi_walk_callback user_function,
 158                        void *context, void **return_value)
 159 {
 160         acpi_status status;
 161         acpi_status mutex_status;
 162         struct acpi_namespace_node *child_node;
 163         struct acpi_namespace_node *parent_node;
 164         acpi_object_type child_type;
 165         u32 level;
 166
 167         ACPI_FUNCTION_TRACE(ns_walk_namespace);
 168
 169         /* Special case for the namespace Root Node */
 170
 171         if (start_node == ACPI_ROOT_OBJECT) {
 172                 start_node = acpi_gbl_root_node;
 173         }
 174
 175         /* Null child means "get first node" */
 176
 177         parent_node = start_node;
 178         child_node = NULL;
 179         child_type = ACPI_TYPE_ANY;
 180         level = 1;
 181
 182         /*
 183          * Traverse the tree of nodes until we bubble back up to where we
 184          * started. When Level is zero, the loop is done because we have
 185          * bubbled up to (and passed) the original parent handle (start_entry)
 186          */
 187         while (level > 0) {
 188
 189                 /* Get the next node in this scope.  Null if not found */
 190
 191                 status = AE_OK;
 192                 child_node =
 193                     acpi_ns_get_next_node(ACPI_TYPE_ANY, parent_node,
 194                                           child_node);
 195                 if (child_node) {
 196
 197                         /* Found next child, get the type if we are not searching for ANY */
 198
 199                         if (type != ACPI_TYPE_ANY) {
 200                                 child_type = child_node->type;
 201                         }
 202
 203                         /*
 204                          * Ignore all temporary namespace nodes (created during control
 205                          * method execution) unless told otherwise. These temporary nodes
 206                          * can cause a race condition because they can be deleted during the
 207                          * execution of the user function (if the namespace is unlocked before
 208                          * invocation of the user function.) Only the debugger namespace dump
 209                          * will examine the temporary nodes.
 210                          */
 211                         if ((child_node->flags & ANOBJ_TEMPORARY) &&
 212                             !(flags & ACPI_NS_WALK_TEMP_NODES)) {
 213                                 status = AE_CTRL_DEPTH;
 214                         }
 215
 216                         /* Type must match requested type */
 217
 218                         else if (child_type == type) {
 219                                 /*
 220                                  * Found a matching node, invoke the user callback function.
 221                                  * Unlock the namespace if flag is set.
 222                                  */
 223                                 if (flags & ACPI_NS_WALK_UNLOCK) {
 224                                         mutex_status =
 225                                             acpi_ut_release_mutex
 226                                             (ACPI_MTX_NAMESPACE);
 227                                         if (ACPI_FAILURE(mutex_status)) {
 228                                                 return_ACPI_STATUS
 229                                                     (mutex_status);
 230                                         }
 231                                 }
 232
 233                                 status =
 234                                     user_function(child_node, level, context,
 235                                                   return_value);
 236
 237                                 if (flags & ACPI_NS_WALK_UNLOCK) {
 238                                         mutex_status =
 239                                             acpi_ut_acquire_mutex
 240                                             (ACPI_MTX_NAMESPACE);
 241                                         if (ACPI_FAILURE(mutex_status)) {
 242                                                 return_ACPI_STATUS
 243                                                     (mutex_status);
 244                                         }
 245                                 }
 246
 247                                 switch (status) {
 248                                 case AE_OK:
 249                                 case AE_CTRL_DEPTH:
 250
 251                                         /* Just keep going */
 252                                         break;
 253
 254                                 case AE_CTRL_TERMINATE:
 255
 256                                         /* Exit now, with OK status */
 257
 258                                         return_ACPI_STATUS(AE_OK);
 259
 260                                 default:
 261
 262                                         /* All others are valid exceptions */
 263
 264                                         return_ACPI_STATUS(status);
 265                                 }
 266                         }
 267
 268                         /*
 269                          * Depth first search: Attempt to go down another level in the
 270                          * namespace if we are allowed to.  Don't go any further if we have
 271                          * reached the caller specified maximum depth or if the user
 272                          * function has specified that the maximum depth has been reached.
 273                          */
 274                         if ((level < max_depth) && (status != AE_CTRL_DEPTH)) {
 275                                 if (acpi_ns_get_next_node
 276                                     (ACPI_TYPE_ANY, child_node, NULL)) {
 277
 278                                         /* There is at least one child of this node, visit it */
 279
 280                                         level++;
 281                                         parent_node = child_node;
 282                                         child_node = NULL;
 283                                 }
 284                         }
 285                 } else {
 286                         /*
 287                          * No more children of this node (acpi_ns_get_next_node failed), go
 288                          * back upwards in the namespace tree to the node's parent.
 289                          */
 290                         level--;
 291                         child_node = parent_node;
 292                         parent_node = acpi_ns_get_parent_node(parent_node);
 293                 }
 294         }
 295
 296         /* Complete walk, not terminated by user function */
 297
 298         return_ACPI_STATUS(AE_OK);
 299 }