nsxfeval.c

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/*******************************************************************************
 *
 * Module Name: nsxfeval - Public interfaces to the ACPI subsystem
 *                         ACPI Object evaluation interfaces
 *
 ******************************************************************************/

/*
 * Copyright (C) 2000 - 2012, Intel Corp.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 */

#include <linux/export.h>
#include <acpi/acpi.h>
#include "accommon.h"
#include "acnamesp.h"
#include "acinterp.h"

#define _COMPONENT          ACPI_NAMESPACE
ACPI_MODULE_NAME("nsxfeval")

/* Local prototypes */
static void acpi_ns_resolve_references(struct acpi_evaluate_info *info);

/*******************************************************************************
 *
 * FUNCTION:    acpi_evaluate_object_typed
 *
 * PARAMETERS:  handle              - Object handle (optional)
 *              pathname            - Object pathname (optional)
 *              external_params     - List of parameters to pass to method,
 *                                    terminated by NULL.  May be NULL
 *                                    if no parameters are being passed.
 *              return_buffer       - Where to put method's return value (if
 *                                    any).  If NULL, no value is returned.
 *              return_type         - Expected type of return object
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Find and evaluate the given object, passing the given
 *              parameters if necessary.  One of "Handle" or "Pathname" must
 *              be valid (non-null)
 *
 ******************************************************************************/

acpi_status
acpi_evaluate_object_typed(acpi_handle handle,
               acpi_string pathname,
               struct acpi_object_list *external_params,
               struct acpi_buffer *return_buffer,
               acpi_object_type return_type)
{
    acpi_status status;
    u8 must_free = FALSE;

    ACPI_FUNCTION_TRACE(acpi_evaluate_object_typed);

    /* Return buffer must be valid */

    if (!return_buffer) {
        return_ACPI_STATUS(AE_BAD_PARAMETER);
    }

    if (return_buffer->length == ACPI_ALLOCATE_BUFFER) {
        must_free = TRUE;
    }

    /* Evaluate the object */

    status =
        acpi_evaluate_object(handle, pathname, external_params,
                 return_buffer);
    if (ACPI_FAILURE(status)) {
        return_ACPI_STATUS(status);
    }

    /* Type ANY means "don't care" */

    if (return_type == ACPI_TYPE_ANY) {
        return_ACPI_STATUS(AE_OK);
    }

    if (return_buffer->length == 0) {

        /* Error because caller specifically asked for a return value */

        ACPI_ERROR((AE_INFO, "No return value"));
        return_ACPI_STATUS(AE_NULL_OBJECT);
    }

    /* Examine the object type returned from evaluate_object */

    if (((union acpi_object *)return_buffer->pointer)->type == return_type) {
        return_ACPI_STATUS(AE_OK);
    }

    /* Return object type does not match requested type */

    ACPI_ERROR((AE_INFO,
            "Incorrect return type [%s] requested [%s]",
            acpi_ut_get_type_name(((union acpi_object *)return_buffer->
                       pointer)->type),
            acpi_ut_get_type_name(return_type)));

    if (must_free) {

        /* Caller used ACPI_ALLOCATE_BUFFER, free the return buffer */

        ACPI_FREE(return_buffer->pointer);
        return_buffer->pointer = NULL;
    }

    return_buffer->length = 0;
    return_ACPI_STATUS(AE_TYPE);
}

ACPI_EXPORT_SYMBOL(acpi_evaluate_object_typed)

/*******************************************************************************
 *
 * FUNCTION:    acpi_evaluate_object
 *
 * PARAMETERS:  handle              - Object handle (optional)
 *              pathname            - Object pathname (optional)
 *              external_params     - List of parameters to pass to method,
 *                                    terminated by NULL.  May be NULL
 *                                    if no parameters are being passed.
 *              return_buffer       - Where to put method's return value (if
 *                                    any).  If NULL, no value is returned.
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Find and evaluate the given object, passing the given
 *              parameters if necessary.  One of "Handle" or "Pathname" must
 *              be valid (non-null)
 *
 ******************************************************************************/
acpi_status
acpi_evaluate_object(acpi_handle handle,
             acpi_string pathname,
             struct acpi_object_list *external_params,
             struct acpi_buffer *return_buffer)
{
    acpi_status status;
    struct acpi_evaluate_info *info;
    acpi_size buffer_space_needed;
    u32 i;

    ACPI_FUNCTION_TRACE(acpi_evaluate_object);

    /* Allocate and initialize the evaluation information block */

    info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
    if (!info) {
        return_ACPI_STATUS(AE_NO_MEMORY);
    }

    info->pathname = pathname;

    /* Convert and validate the device handle */

    info->prefix_node = acpi_ns_validate_handle(handle);
    if (!info->prefix_node) {
        status = AE_BAD_PARAMETER;
        goto cleanup;
    }

    /*
     * If there are parameters to be passed to a control method, the external
     * objects must all be converted to internal objects
     */
    if (external_params && external_params->count) {
        /*
         * Allocate a new parameter block for the internal objects
         * Add 1 to count to allow for null terminated internal list
         */
        info->parameters = ACPI_ALLOCATE_ZEROED(((acpi_size)
                             external_params->
                             count +
                             1) * sizeof(void *));
        if (!info->parameters) {
            status = AE_NO_MEMORY;
            goto cleanup;
        }

        /* Convert each external object in the list to an internal object */

        for (i = 0; i < external_params->count; i++) {
            status =
                acpi_ut_copy_eobject_to_iobject(&external_params->
                                pointer[i],
                                &info->
                                parameters[i]);
            if (ACPI_FAILURE(status)) {
                goto cleanup;
            }
        }
        info->parameters[external_params->count] = NULL;
    }

    /*
     * Three major cases:
     * 1) Fully qualified pathname
     * 2) No handle, not fully qualified pathname (error)
     * 3) Valid handle
     */
    if ((pathname) && (acpi_ns_valid_root_prefix(pathname[0]))) {

        /* The path is fully qualified, just evaluate by name */

        info->prefix_node = NULL;
        status = acpi_ns_evaluate(info);
    } else if (!handle) {
        /*
         * A handle is optional iff a fully qualified pathname is specified.
         * Since we've already handled fully qualified names above, this is
         * an error
         */
        if (!pathname) {
            ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                      "Both Handle and Pathname are NULL"));
        } else {
            ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                      "Null Handle with relative pathname [%s]",
                      pathname));
        }

        status = AE_BAD_PARAMETER;
    } else {
        /* We have a namespace a node and a possible relative path */

        status = acpi_ns_evaluate(info);
    }

    /*
     * If we are expecting a return value, and all went well above,
     * copy the return value to an external object.
     */
    if (return_buffer) {
        if (!info->return_object) {
            return_buffer->length = 0;
        } else {
            if (ACPI_GET_DESCRIPTOR_TYPE(info->return_object) ==
                ACPI_DESC_TYPE_NAMED) {
                /*
                 * If we received a NS Node as a return object, this means that
                 * the object we are evaluating has nothing interesting to
                 * return (such as a mutex, etc.)  We return an error because
                 * these types are essentially unsupported by this interface.
                 * We don't check up front because this makes it easier to add
                 * support for various types at a later date if necessary.
                 */
                status = AE_TYPE;
                info->return_object = NULL; /* No need to delete a NS Node */
                return_buffer->length = 0;
            }

            if (ACPI_SUCCESS(status)) {

                /* Dereference Index and ref_of references */

                acpi_ns_resolve_references(info);

                /* Get the size of the returned object */

                status =
                    acpi_ut_get_object_size(info->return_object,
                                &buffer_space_needed);
                if (ACPI_SUCCESS(status)) {

                    /* Validate/Allocate/Clear caller buffer */

                    status =
                        acpi_ut_initialize_buffer
                        (return_buffer,
                         buffer_space_needed);
                    if (ACPI_FAILURE(status)) {
                        /*
                         * Caller's buffer is too small or a new one can't
                         * be allocated
                         */
                        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                  "Needed buffer size %X, %s\n",
                                  (u32)
                                  buffer_space_needed,
                                  acpi_format_exception
                                  (status)));
                    } else {
                        /* We have enough space for the object, build it */

                        status =
                            acpi_ut_copy_iobject_to_eobject
                            (info->return_object,
                             return_buffer);
                    }
                }
            }
        }
    }

    if (info->return_object) {
        /*
         * Delete the internal return object. NOTE: Interpreter must be
         * locked to avoid race condition.
         */
        acpi_ex_enter_interpreter();

        /* Remove one reference on the return object (should delete it) */

        acpi_ut_remove_reference(info->return_object);
        acpi_ex_exit_interpreter();
    }

      cleanup:

    /* Free the input parameter list (if we created one) */

    if (info->parameters) {

        /* Free the allocated parameter block */

        acpi_ut_delete_internal_object_list(info->parameters);
    }

    ACPI_FREE(info);
    return_ACPI_STATUS(status);
}

ACPI_EXPORT_SYMBOL(acpi_evaluate_object)

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_resolve_references
 *
 * PARAMETERS:  info                    - Evaluation info block
 *
 * RETURN:      Info->return_object is replaced with the dereferenced object
 *
 * DESCRIPTION: Dereference certain reference objects. Called before an
 *              internal return object is converted to an external union acpi_object.
 *
 * Performs an automatic dereference of Index and ref_of reference objects.
 * These reference objects are not supported by the union acpi_object, so this is a
 * last resort effort to return something useful. Also, provides compatibility
 * with other ACPI implementations.
 *
 * NOTE: does not handle references within returned package objects or nested
 * references, but this support could be added later if found to be necessary.
 *
 ******************************************************************************/
static void acpi_ns_resolve_references(struct acpi_evaluate_info *info)
{
    union acpi_operand_object *obj_desc = NULL;
    struct acpi_namespace_node *node;

    /* We are interested in reference objects only */

    if ((info->return_object)->common.type != ACPI_TYPE_LOCAL_REFERENCE) {
        return;
    }

    /*
     * Two types of references are supported - those created by Index and
     * ref_of operators. A name reference (AML_NAMEPATH_OP) can be converted
     * to an union acpi_object, so it is not dereferenced here. A ddb_handle
     * (AML_LOAD_OP) cannot be dereferenced, nor can it be converted to
     * an union acpi_object.
     */
    switch (info->return_object->reference.class) {
    case ACPI_REFCLASS_INDEX:

        obj_desc = *(info->return_object->reference.where);
        break;

    case ACPI_REFCLASS_REFOF:

        node = info->return_object->reference.object;
        if (node) {
            obj_desc = node->object;
        }
        break;

    default:
        return;
    }

    /* Replace the existing reference object */

    if (obj_desc) {
        acpi_ut_add_reference(obj_desc);
        acpi_ut_remove_reference(info->return_object);
        info->return_object = obj_desc;
    }

    return;
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_walk_namespace
 *
 * PARAMETERS:  type                - acpi_object_type to search for
 *              start_object        - Handle in namespace where search begins
 *              max_depth           - Depth to which search is to reach
 *              pre_order_visit     - Called during tree pre-order visit
 *                                    when an object of "Type" is found
 *              post_order_visit    - Called during tree post-order visit
 *                                    when an object of "Type" is found
 *              context             - Passed to user function(s) above
 *              return_value        - Location where return value of
 *                                    user_function is put if terminated early
 *
 * RETURNS      Return value from the user_function if terminated early.
 *              Otherwise, returns NULL.
 *
 * DESCRIPTION: Performs a modified depth-first walk of the namespace tree,
 *              starting (and ending) at the object specified by start_handle.
 *              The callback function is called whenever an object 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_walk_namespace(acpi_object_type type,
            acpi_handle start_object,
            u32 max_depth,
            acpi_walk_callback pre_order_visit,
            acpi_walk_callback post_order_visit,
            void *context, void **return_value)
{
    acpi_status status;

    ACPI_FUNCTION_TRACE(acpi_walk_namespace);

    /* Parameter validation */

    if ((type > ACPI_TYPE_LOCAL_MAX) ||
        (!max_depth) || (!pre_order_visit && !post_order_visit)) {
        return_ACPI_STATUS(AE_BAD_PARAMETER);
    }

    /*
     * Need to acquire the namespace reader lock to prevent interference
     * with any concurrent table unloads (which causes the deletion of
     * namespace objects). We cannot allow the deletion of a namespace node
     * while the user function is using it. The exception to this are the
     * nodes created and deleted during control method execution -- these
     * nodes are marked as temporary nodes and are ignored by the namespace
     * walk. Thus, control methods can be executed while holding the
     * namespace deletion lock (and the user function can execute control
     * methods.)
     */
    status = acpi_ut_acquire_read_lock(&acpi_gbl_namespace_rw_lock);
    if (ACPI_FAILURE(status)) {
        return status;
    }

    /*
     * Lock the namespace around the walk. The namespace will be
     * unlocked/locked around each call to the user function - since the user
     * function must be allowed to make ACPICA calls itself (for example, it
     * will typically execute control methods during device enumeration.)
     */
    status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
    if (ACPI_FAILURE(status)) {
        goto unlock_and_exit;
    }

    status = acpi_ns_walk_namespace(type, start_object, max_depth,
                    ACPI_NS_WALK_UNLOCK, pre_order_visit,
                    post_order_visit, context,
                    return_value);

    (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);

      unlock_and_exit:
    (void)acpi_ut_release_read_lock(&acpi_gbl_namespace_rw_lock);
    return_ACPI_STATUS(status);
}

ACPI_EXPORT_SYMBOL(acpi_walk_namespace)

/*******************************************************************************
 *
 * FUNCTION:    acpi_ns_get_device_callback
 *
 * PARAMETERS:  Callback from acpi_get_device
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Takes callbacks from walk_namespace and filters out all non-
 *              present devices, or if they specified a HID, it filters based
 *              on that.
 *
 ******************************************************************************/
static acpi_status
acpi_ns_get_device_callback(acpi_handle obj_handle,
                u32 nesting_level,
                void *context, void **return_value)
{
    struct acpi_get_devices_info *info = context;
    acpi_status status;
    struct acpi_namespace_node *node;
    u32 flags;
    struct acpica_device_id *hid;
    struct acpica_device_id_list *cid;
    u32 i;
    u8 found;
    int no_match;

    status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
    if (ACPI_FAILURE(status)) {
        return (status);
    }

    node = acpi_ns_validate_handle(obj_handle);
    status = acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
    if (ACPI_FAILURE(status)) {
        return (status);
    }

    if (!node) {
        return (AE_BAD_PARAMETER);
    }

    /*
     * First, filter based on the device HID and CID.
     *
     * 01/2010: For this case where a specific HID is requested, we don't
     * want to run _STA until we have an actual HID match. Thus, we will
     * not unnecessarily execute _STA on devices for which the caller
     * doesn't care about. Previously, _STA was executed unconditionally
     * on all devices found here.
     *
     * A side-effect of this change is that now we will continue to search
     * for a matching HID even under device trees where the parent device
     * would have returned a _STA that indicates it is not present or
     * not functioning (thus aborting the search on that branch).
     */
    if (info->hid != NULL) {
        status = acpi_ut_execute_HID(node, &hid);
        if (status == AE_NOT_FOUND) {
            return (AE_OK);
        } else if (ACPI_FAILURE(status)) {
            return (AE_CTRL_DEPTH);
        }

        no_match = ACPI_STRCMP(hid->string, info->hid);
        ACPI_FREE(hid);

        if (no_match) {
            /*
             * HID does not match, attempt match within the
             * list of Compatible IDs (CIDs)
             */
            status = acpi_ut_execute_CID(node, &cid);
            if (status == AE_NOT_FOUND) {
                return (AE_OK);
            } else if (ACPI_FAILURE(status)) {
                return (AE_CTRL_DEPTH);
            }

            /* Walk the CID list */

            found = 0;
            for (i = 0; i < cid->count; i++) {
                if (ACPI_STRCMP(cid->ids[i].string, info->hid)
                    == 0) {
                    found = 1;
                    break;
                }
            }
            ACPI_FREE(cid);
            if (!found)
                return (AE_OK);
        }
    }

    /* Run _STA to determine if device is present */

    status = acpi_ut_execute_STA(node, &flags);
    if (ACPI_FAILURE(status)) {
        return (AE_CTRL_DEPTH);
    }

    if (!(flags & ACPI_STA_DEVICE_PRESENT) &&
        !(flags & ACPI_STA_DEVICE_FUNCTIONING)) {
        /*
         * Don't examine the children of the device only when the
         * device is neither present nor functional. See ACPI spec,
         * description of _STA for more information.
         */
        return (AE_CTRL_DEPTH);
    }

    /* We have a valid device, invoke the user function */

    status = info->user_function(obj_handle, nesting_level, info->context,
                     return_value);
    return (status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_get_devices
 *
 * PARAMETERS:  HID                 - HID to search for. Can be NULL.
 *              user_function       - Called when a matching object is found
 *              context             - Passed to user function
 *              return_value        - Location where return value of
 *                                    user_function is put if terminated early
 *
 * RETURNS      Return value from the user_function if terminated early.
 *              Otherwise, returns NULL.
 *
 * DESCRIPTION: Performs a modified depth-first walk of the namespace tree,
 *              starting (and ending) at the object specified by start_handle.
 *              The user_function is called whenever an object of type
 *              Device is found.  If the user function returns
 *              a non-zero value, the search is terminated immediately and this
 *              value is returned to the caller.
 *
 *              This is a wrapper for walk_namespace, but the callback performs
 *              additional filtering. Please see acpi_ns_get_device_callback.
 *
 ******************************************************************************/

acpi_status
acpi_get_devices(const char *HID,
         acpi_walk_callback user_function,
         void *context, void **return_value)
{
    acpi_status status;
    struct acpi_get_devices_info info;

    ACPI_FUNCTION_TRACE(acpi_get_devices);

    /* Parameter validation */

    if (!user_function) {
        return_ACPI_STATUS(AE_BAD_PARAMETER);
    }

    /*
     * We're going to call their callback from OUR callback, so we need
     * to know what it is, and their context parameter.
     */
    info.hid = HID;
    info.context = context;
    info.user_function = user_function;

    /*
     * Lock the namespace around the walk.
     * The namespace will be unlocked/locked around each call
     * to the user function - since this function
     * must be allowed to make Acpi calls itself.
     */
    status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
    if (ACPI_FAILURE(status)) {
        return_ACPI_STATUS(status);
    }

    status = acpi_ns_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
                    ACPI_UINT32_MAX, ACPI_NS_WALK_UNLOCK,
                    acpi_ns_get_device_callback, NULL,
                    &info, return_value);

    (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
    return_ACPI_STATUS(status);
}

ACPI_EXPORT_SYMBOL(acpi_get_devices)

/*******************************************************************************
 *
 * FUNCTION:    acpi_attach_data
 *
 * PARAMETERS:  obj_handle          - Namespace node
 *              handler             - Handler for this attachment
 *              data                - Pointer to data to be attached
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Attach arbitrary data and handler to a namespace node.
 *
 ******************************************************************************/
acpi_status
acpi_attach_data(acpi_handle obj_handle,
         acpi_object_handler handler, void *data)
{
    struct acpi_namespace_node *node;
    acpi_status status;

    /* Parameter validation */

    if (!obj_handle || !handler || !data) {
        return (AE_BAD_PARAMETER);
    }

    status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
    if (ACPI_FAILURE(status)) {
        return (status);
    }

    /* Convert and validate the handle */

    node = acpi_ns_validate_handle(obj_handle);
    if (!node) {
        status = AE_BAD_PARAMETER;
        goto unlock_and_exit;
    }

    status = acpi_ns_attach_data(node, handler, data);

      unlock_and_exit:
    (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
    return (status);
}

ACPI_EXPORT_SYMBOL(acpi_attach_data)

/*******************************************************************************
 *
 * FUNCTION:    acpi_detach_data
 *
 * PARAMETERS:  obj_handle          - Namespace node handle
 *              handler             - Handler used in call to acpi_attach_data
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Remove data that was previously attached to a node.
 *
 ******************************************************************************/
acpi_status
acpi_detach_data(acpi_handle obj_handle, acpi_object_handler handler)
{
    struct acpi_namespace_node *node;
    acpi_status status;

    /* Parameter validation */

    if (!obj_handle || !handler) {
        return (AE_BAD_PARAMETER);
    }

    status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
    if (ACPI_FAILURE(status)) {
        return (status);
    }

    /* Convert and validate the handle */

    node = acpi_ns_validate_handle(obj_handle);
    if (!node) {
        status = AE_BAD_PARAMETER;
        goto unlock_and_exit;
    }

    status = acpi_ns_detach_data(node, handler);

      unlock_and_exit:
    (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
    return (status);
}

ACPI_EXPORT_SYMBOL(acpi_detach_data)

/*******************************************************************************
 *
 * FUNCTION:    acpi_get_data
 *
 * PARAMETERS:  obj_handle          - Namespace node
 *              handler             - Handler used in call to attach_data
 *              data                - Where the data is returned
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Retrieve data that was previously attached to a namespace node.
 *
 ******************************************************************************/
acpi_status
acpi_get_data(acpi_handle obj_handle, acpi_object_handler handler, void **data)
{
    struct acpi_namespace_node *node;
    acpi_status status;

    /* Parameter validation */

    if (!obj_handle || !handler || !data) {
        return (AE_BAD_PARAMETER);
    }

    status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
    if (ACPI_FAILURE(status)) {
        return (status);
    }

    /* Convert and validate the handle */

    node = acpi_ns_validate_handle(obj_handle);
    if (!node) {
        status = AE_BAD_PARAMETER;
        goto unlock_and_exit;
    }

    status = acpi_ns_get_attached_data(node, handler, data);

      unlock_and_exit:
    (void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
    return (status);
}

ACPI_EXPORT_SYMBOL(acpi_get_data)