linux/drivers/acpi/acpica/nssearch.c

// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/*******************************************************************************
 *
 * Module Name: nssearch - Namespace search
 *
 ******************************************************************************/

#include <acpi/acpi.h>
#include "accommon.h"
#include "acnamesp.h"

#ifdef ACPI_ASL_COMPILER
#include "amlcode.h"
#endif

#define _COMPONENT …
ACPI_MODULE_NAME("nssearch")

/* Local prototypes */
static acpi_status
acpi_ns_search_parent_tree(u32 target_name,
			   struct acpi_namespace_node *node,
			   acpi_object_type type,
			   struct acpi_namespace_node **return_node);

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_search_one_scope
 *
 * PARAMETERS:  target_name     - Ascii ACPI name to search for
 *              parent_node     - Starting node where search will begin
 *              type            - Object type to match
 *              return_node     - Where the matched Named obj is returned
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Search a single level of the namespace. Performs a
 *              simple search of the specified level, and does not add
 *              entries or search parents.
 *
 *
 *      Named object lists are built (and subsequently dumped) in the
 *      order in which the names are encountered during the namespace load;
 *
 *      All namespace searching is linear in this implementation, but
 *      could be easily modified to support any improved search
 *      algorithm. However, the linear search was chosen for simplicity
 *      and because the trees are small and the other interpreter
 *      execution overhead is relatively high.
 *
 *      Note: CPU execution analysis has shown that the AML interpreter spends
 *      a very small percentage of its time searching the namespace. Therefore,
 *      the linear search seems to be sufficient, as there would seem to be
 *      little value in improving the search.
 *
 ******************************************************************************/

acpi_status
acpi_ns_search_one_scope(u32 target_name,
			 struct acpi_namespace_node *parent_node,
			 acpi_object_type type,
			 struct acpi_namespace_node **return_node)
{ … }

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_search_parent_tree
 *
 * PARAMETERS:  target_name     - Ascii ACPI name to search for
 *              node            - Starting node where search will begin
 *              type            - Object type to match
 *              return_node     - Where the matched Node is returned
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Called when a name has not been found in the current namespace
 *              level. Before adding it or giving up, ACPI scope rules require
 *              searching enclosing scopes in cases identified by acpi_ns_local().
 *
 *              "A name is located by finding the matching name in the current
 *              name space, and then in the parent name space. If the parent
 *              name space does not contain the name, the search continues
 *              recursively until either the name is found or the name space
 *              does not have a parent (the root of the name space). This
 *              indicates that the name is not found" (From ACPI Specification,
 *              section 5.3)
 *
 ******************************************************************************/

static acpi_status
acpi_ns_search_parent_tree(u32 target_name,
			   struct acpi_namespace_node *node,
			   acpi_object_type type,
			   struct acpi_namespace_node **return_node)
{ … }

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_search_and_enter
 *
 * PARAMETERS:  target_name         - Ascii ACPI name to search for (4 chars)
 *              walk_state          - Current state of the walk
 *              node                - Starting node where search will begin
 *              interpreter_mode    - Add names only in ACPI_MODE_LOAD_PASS_x.
 *                                    Otherwise,search only.
 *              type                - Object type to match
 *              flags               - Flags describing the search restrictions
 *              return_node         - Where the Node is returned
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Search for a name segment in a single namespace level,
 *              optionally adding it if it is not found. If the passed
 *              Type is not Any and the type previously stored in the
 *              entry was Any (i.e. unknown), update the stored type.
 *
 *              In ACPI_IMODE_EXECUTE, search only.
 *              In other modes, search and add if not found.
 *
 ******************************************************************************/

acpi_status
acpi_ns_search_and_enter(u32 target_name,
			 struct acpi_walk_state *walk_state,
			 struct acpi_namespace_node *node,
			 acpi_interpreter_mode interpreter_mode,
			 acpi_object_type type,
			 u32 flags, struct acpi_namespace_node **return_node)
{ … }