// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/******************************************************************************
*
* Module Name: nswalk - Functions for walking the ACPI namespace
*
* Copyright (C) 2000 - 2025, Intel Corp.
*
*****************************************************************************/
#include <acpi/acpi.h>
#include "accommon.h"
#include "acnamesp.h"
#define _COMPONENT ACPI_NAMESPACE
ACPI_MODULE_NAME(
"nswalk")
/*******************************************************************************
*
* FUNCTION: acpi_ns_get_next_node
*
* PARAMETERS: parent_node - Parent node whose children we are
* getting
* child_node - Previous child that was found.
* The NEXT child will be returned
*
* RETURN: struct acpi_namespace_node - Pointer to the NEXT child or NULL if
* none is found.
*
* DESCRIPTION: Return the next peer node within the namespace. If Handle
* is valid, Scope is ignored. Otherwise, the first node
* within Scope is returned.
*
******************************************************************************/
struct acpi_namespace_node *acpi_ns_get_next_node(
struct acpi_namespace_node
*parent_node,
struct acpi_namespace_node
*child_node)
{
ACPI_FUNCTION_ENTRY();
if (!child_node) {
/* It's really the parent's _scope_ that we want */
return (parent_node->child);
}
/* Otherwise just return the next peer */
return (child_node->peer);
}
/*******************************************************************************
*
* FUNCTION: acpi_ns_get_next_node_typed
*
* PARAMETERS: type - Type of node to be searched for
* parent_node - Parent node whose children we are
* getting
* child_node - Previous child that was found.
* The NEXT child will be returned
*
* RETURN: struct acpi_namespace_node - Pointer to the NEXT child or NULL if
* none is found.
*
* DESCRIPTION: Return the next peer node within the namespace. If Handle
* is valid, Scope is ignored. Otherwise, the first node
* within Scope is returned.
*
******************************************************************************/
struct acpi_namespace_node *acpi_ns_get_next_node_typed(acpi_object_type type,
struct
acpi_namespace_node
*parent_node,
struct
acpi_namespace_node
*child_node)
{
struct acpi_namespace_node *next_node = NULL;
ACPI_FUNCTION_ENTRY();
next_node = acpi_ns_get_next_node(parent_node, child_node);
/* If any type is OK, we are done */
if (type == ACPI_TYPE_ANY) {
/* next_node is NULL if we are at the end-of-list */
return (next_node);
}
/* Must search for the node -- but within this scope only */
while (next_node) {
/* If type matches, we are done */
if (next_node->type == type) {
return (next_node);
}
/* Otherwise, move on to the next peer node */
next_node = next_node->peer;
}
/* Not found */
return (NULL);
}
/*******************************************************************************
*
* FUNCTION: acpi_ns_walk_namespace
*
* PARAMETERS: type - acpi_object_type to search for
* start_node - Handle in namespace where search begins
* max_depth - Depth to which search is to reach
* flags - Whether to unlock the NS before invoking
* the callback routine
* descending_callback - Called during tree descent
* when an object of "Type" is found
* ascending_callback - Called during tree ascent
* when an object of "Type" is found
* context - Passed to user function(s) above
* return_value - from the user_function if terminated
* early. Otherwise, returns NULL.
* RETURNS: Status
*
* DESCRIPTION: Performs a modified depth-first walk of the namespace tree,
* starting (and ending) at the node specified by start_handle.
* The callback function is called whenever a node that matches
* the type parameter is found. If the callback function returns
* a non-zero value, the search is terminated immediately and
* this value is returned to the caller.
*
* The point of this procedure is to provide a generic namespace
* walk routine that can be called from multiple places to
* provide multiple services; the callback function(s) can be
* tailored to each task, whether it is a print function,
* a compare function, etc.
*
******************************************************************************/
acpi_status
acpi_ns_walk_namespace(acpi_object_type type,
acpi_handle start_node,
u32 max_depth,
u32 flags,
acpi_walk_callback descending_callback,
acpi_walk_callback ascending_callback,
void *context,
void **return_value)
{
acpi_status status;
acpi_status mutex_status;
struct acpi_namespace_node *child_node;
struct acpi_namespace_node *parent_node;
acpi_object_type child_type;
u32 level;
u8 node_previously_visited =
FALSE;
ACPI_FUNCTION_TRACE(ns_walk_namespace);
/* Special case for the namespace Root Node */
if (start_node == ACPI_ROOT_OBJECT) {
start_node = acpi_gbl_root_node;
if (!start_node) {
return_ACPI_STATUS(AE_NO_NAMESPACE);
}
}
/* Null child means "get first node" */
parent_node = start_node;
child_node = acpi_ns_get_next_node(parent_node, NULL);
child_type = ACPI_TYPE_ANY;
level =
1;
/*
* Traverse the tree of nodes until we bubble back up to where we
* started. When Level is zero, the loop is done because we have
* bubbled up to (and passed) the original parent handle (start_entry)
*/
while (level >
0 && child_node) {
status = AE_OK;
/* Found next child, get the type if we are not searching for ANY */
if (type != ACPI_TYPE_ANY) {
child_type = child_node->type;
}
/*
* Ignore all temporary namespace nodes (created during control
* method execution) unless told otherwise. These temporary nodes
* can cause a race condition because they can be deleted during
* the execution of the user function (if the namespace is
* unlocked before invocation of the user function.) Only the
* debugger namespace dump will examine the temporary nodes.
*/
if ((child_node->flags & ANOBJ_TEMPORARY) &&
!(flags & ACPI_NS_WALK_TEMP_NODES)) {
status = AE_CTRL_DEPTH;
}
/* Type must match requested type */
else if (child_type == type) {
/*
* Found a matching node, invoke the user callback function.
* Unlock the namespace if flag is set.
*/
if (flags & ACPI_NS_WALK_UNLOCK) {
mutex_status =
acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
if (ACPI_FAILURE(mutex_status)) {
return_ACPI_STATUS(mutex_status);
}
}
/*
* Invoke the user function, either descending, ascending,
* or both.
*/
if (!node_previously_visited) {
if (descending_callback) {
status =
descending_callback(child_node,
level, context,
return_value);
}
}
else {
if (ascending_callback) {
status =
ascending_callback(child_node,
level, context,
return_value);
}
}
if (flags & ACPI_NS_WALK_UNLOCK) {
mutex_status =
acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
if (ACPI_FAILURE(mutex_status)) {
return_ACPI_STATUS(mutex_status);
}
}
switch (status) {
case AE_OK:
case AE_CTRL_DEPTH:
/* Just keep going */
break;
case AE_CTRL_TERMINATE:
/* Exit now, with OK status */
return_ACPI_STATUS(AE_OK);
default:
/* All others are valid exceptions */
return_ACPI_STATUS(status);
}
}
/*
* Depth first search: Attempt to go down another level in the
* namespace if we are allowed to. Don't go any further if we have
* reached the caller specified maximum depth or if the user
* function has specified that the maximum depth has been reached.
*/
if (!node_previously_visited &&
(level < max_depth) && (status != AE_CTRL_DEPTH)) {
if (child_node->child) {
/* There is at least one child of this node, visit it */
level++;
parent_node = child_node;
child_node =
acpi_ns_get_next_node(parent_node, NULL);
continue;
}
}
/* No more children, re-visit this node */
if (!node_previously_visited) {
node_previously_visited =
TRUE;
continue;
}
/* No more children, visit peers */
child_node = acpi_ns_get_next_node(parent_node, child_node);
if (child_node) {
node_previously_visited =
FALSE;
}
/* No peers, re-visit parent */
else {
/*
* No more children of this node (acpi_ns_get_next_node failed), go
* back upwards in the namespace tree to the node's parent.
*/
level--;
child_node = parent_node;
parent_node = parent_node->parent;
node_previously_visited =
TRUE;
}
}
/* Complete walk, not terminated by user function */
return_ACPI_STATUS(AE_OK);
}
