components/namespace/nsxfeval.c

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

/*
 * Copyright (C) 2000 - 2015, 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.
 */

#define EXPORT_ACPI_INTERFACES

#include <contrib/dev/acpica/include/acpi.h>
#include <contrib/dev/acpica/include/accommon.h>
#include <contrib/dev/acpica/include/acnamesp.h>
#include <contrib/dev/acpica/include/acinterp.h>


#define _COMPONENT          ACPI_NAMESPACE
        ACPI_MODULE_NAME    ("nsxfeval")

/* Local prototypes */

static void
AcpiNsResolveReferences (
    ACPI_EVALUATE_INFO      *Info);


/*******************************************************************************
 *
 * FUNCTION:    AcpiEvaluateObjectTyped
 *
 * PARAMETERS:  Handle              - Object handle (optional)
 *              Pathname            - Object pathname (optional)
 *              ExternalParams      - List of parameters to pass to method,
 *                                    terminated by NULL. May be NULL
 *                                    if no parameters are being passed.
 *              ReturnBuffer        - Where to put method's return value (if
 *                                    any). If NULL, no value is returned.
 *              ReturnType          - 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
AcpiEvaluateObjectTyped (
    ACPI_HANDLE             Handle,
    ACPI_STRING             Pathname,
    ACPI_OBJECT_LIST        *ExternalParams,
    ACPI_BUFFER             *ReturnBuffer,
    ACPI_OBJECT_TYPE        ReturnType)
{
    ACPI_STATUS             Status;
    BOOLEAN                 FreeBufferOnError = FALSE;


    ACPI_FUNCTION_TRACE (AcpiEvaluateObjectTyped);


    /* Return buffer must be valid */

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

    if (ReturnBuffer->Length == ACPI_ALLOCATE_BUFFER)
    {
        FreeBufferOnError = TRUE;
    }

    /* Evaluate the object */

    Status = AcpiEvaluateObject (Handle, Pathname,
        ExternalParams, ReturnBuffer);
    if (ACPI_FAILURE (Status))
    {
        return_ACPI_STATUS (Status);
    }

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

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

    if (ReturnBuffer->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 EvaluateObject */

    if (((ACPI_OBJECT *) ReturnBuffer->Pointer)->Type == ReturnType)
    {
        return_ACPI_STATUS (AE_OK);
    }

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

    ACPI_ERROR ((AE_INFO,
        "Incorrect return type [%s] requested [%s]",
        AcpiUtGetTypeName (((ACPI_OBJECT *) ReturnBuffer->Pointer)->Type),
        AcpiUtGetTypeName (ReturnType)));

    if (FreeBufferOnError)
    {
        /*
         * Free a buffer created via ACPI_ALLOCATE_BUFFER.
         * Note: We use AcpiOsFree here because AcpiOsAllocate was used
         * to allocate the buffer. This purposefully bypasses the
         * (optionally enabled) allocation tracking mechanism since we
         * only want to track internal allocations.
         */
        AcpiOsFree (ReturnBuffer->Pointer);
        ReturnBuffer->Pointer = NULL;
    }

    ReturnBuffer->Length = 0;
    return_ACPI_STATUS (AE_TYPE);
}

ACPI_EXPORT_SYMBOL (AcpiEvaluateObjectTyped)


/*******************************************************************************
 *
 * FUNCTION:    AcpiEvaluateObject
 *
 * PARAMETERS:  Handle              - Object handle (optional)
 *              Pathname            - Object pathname (optional)
 *              ExternalParams      - List of parameters to pass to method,
 *                                    terminated by NULL. May be NULL
 *                                    if no parameters are being passed.
 *              ReturnBuffer        - 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
AcpiEvaluateObject (
    ACPI_HANDLE             Handle,
    ACPI_STRING             Pathname,
    ACPI_OBJECT_LIST        *ExternalParams,
    ACPI_BUFFER             *ReturnBuffer)
{
    ACPI_STATUS             Status;
    ACPI_EVALUATE_INFO      *Info;
    ACPI_SIZE               BufferSpaceNeeded;
    UINT32                  i;


    ACPI_FUNCTION_TRACE (AcpiEvaluateObject);


    /* Allocate and initialize the evaluation information block */

    Info = ACPI_ALLOCATE_ZEROED (sizeof (ACPI_EVALUATE_INFO));
    if (!Info)
    {
        return_ACPI_STATUS (AE_NO_MEMORY);
    }

    /* Convert and validate the device handle */

    Info->PrefixNode = AcpiNsValidateHandle (Handle);
    if (!Info->PrefixNode)
    {
        Status = AE_BAD_PARAMETER;
        goto Cleanup;
    }

    /*
     * Get the actual namespace node for the target object.
     * Handles these cases:
     *
     * 1) Null node, valid pathname from root (absolute path)
     * 2) Node and valid pathname (path relative to Node)
     * 3) Node, Null pathname
     */
    if ((Pathname) &&
        (ACPI_IS_ROOT_PREFIX (Pathname[0])))
    {
        /* The path is fully qualified, just evaluate by name */

        Info->PrefixNode = NULL;
    }
    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;
        goto Cleanup;
    }

    Info->RelativePathname = Pathname;

    /*
     * Convert all external objects passed as arguments to the
     * internal version(s).
     */
    if (ExternalParams && ExternalParams->Count)
    {
        Info->ParamCount = (UINT16) ExternalParams->Count;

        /* Warn on impossible argument count */

        if (Info->ParamCount > ACPI_METHOD_NUM_ARGS)
        {
            ACPI_WARN_PREDEFINED ((AE_INFO, Pathname, ACPI_WARN_ALWAYS,
                "Excess arguments (%u) - using only %u",
                Info->ParamCount, ACPI_METHOD_NUM_ARGS));

            Info->ParamCount = ACPI_METHOD_NUM_ARGS;
        }

        /*
         * 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) Info->ParamCount + 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 < Info->ParamCount; i++)
        {
            Status = AcpiUtCopyEobjectToIobject (
                &ExternalParams->Pointer[i], &Info->Parameters[i]);
            if (ACPI_FAILURE (Status))
            {
                goto Cleanup;
            }
        }

        Info->Parameters[Info->ParamCount] = NULL;
    }


#if 0

    /*
     * Begin incoming argument count analysis. Check for too few args
     * and too many args.
     */

    switch (AcpiNsGetType (Info->Node))
    {
    case ACPI_TYPE_METHOD:

        /* Check incoming argument count against the method definition */

        if (Info->ObjDesc->Method.ParamCount > Info->ParamCount)
        {
            ACPI_ERROR ((AE_INFO,
                "Insufficient arguments (%u) - %u are required",
                Info->ParamCount,
                Info->ObjDesc->Method.ParamCount));

            Status = AE_MISSING_ARGUMENTS;
            goto Cleanup;
        }

        else if (Info->ObjDesc->Method.ParamCount < Info->ParamCount)
        {
            ACPI_WARNING ((AE_INFO,
                "Excess arguments (%u) - only %u are required",
                Info->ParamCount,
                Info->ObjDesc->Method.ParamCount));

            /* Just pass the required number of arguments */

            Info->ParamCount = Info->ObjDesc->Method.ParamCount;
        }

        /*
         * Any incoming external objects to be passed as arguments to the
         * method must be converted to internal objects
         */
        if (Info->ParamCount)
        {
            /*
             * 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) Info->ParamCount + 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 < Info->ParamCount; i++)
            {
                Status = AcpiUtCopyEobjectToIobject (
                    &ExternalParams->Pointer[i], &Info->Parameters[i]);
                if (ACPI_FAILURE (Status))
                {
                    goto Cleanup;
                }
            }

            Info->Parameters[Info->ParamCount] = NULL;
        }
        break;

    default:

        /* Warn if arguments passed to an object that is not a method */

        if (Info->ParamCount)
        {
            ACPI_WARNING ((AE_INFO,
                "%u arguments were passed to a non-method ACPI object",
                Info->ParamCount));
        }
        break;
    }

#endif


    /* Now we can evaluate the object */

    Status = AcpiNsEvaluate (Info);

    /*
     * If we are expecting a return value, and all went well above,
     * copy the return value to an external object.
     */
    if (ReturnBuffer)
    {
        if (!Info->ReturnObject)
        {
            ReturnBuffer->Length = 0;
        }
        else
        {
            if (ACPI_GET_DESCRIPTOR_TYPE (Info->ReturnObject) ==
                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->ReturnObject = NULL;   /* No need to delete a NS Node */
                ReturnBuffer->Length = 0;
            }

            if (ACPI_SUCCESS (Status))
            {
                /* Dereference Index and RefOf references */

                AcpiNsResolveReferences (Info);

                /* Get the size of the returned object */

                Status = AcpiUtGetObjectSize (Info->ReturnObject,
                            &BufferSpaceNeeded);
                if (ACPI_SUCCESS (Status))
                {
                    /* Validate/Allocate/Clear caller buffer */

                    Status = AcpiUtInitializeBuffer (ReturnBuffer,
                                BufferSpaceNeeded);
                    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",
                            (UINT32) BufferSpaceNeeded,
                            AcpiFormatException (Status)));
                    }
                    else
                    {
                        /* We have enough space for the object, build it */

                        Status = AcpiUtCopyIobjectToEobject (Info->ReturnObject,
                                    ReturnBuffer);
                    }
                }
            }
        }
    }

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

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

        AcpiUtRemoveReference (Info->ReturnObject);
        AcpiExExitInterpreter ();
    }


Cleanup:

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

    if (Info->Parameters)
    {
        /* Free the allocated parameter block */

        AcpiUtDeleteInternalObjectList (Info->Parameters);
    }

    ACPI_FREE (Info);
    return_ACPI_STATUS (Status);
}

ACPI_EXPORT_SYMBOL (AcpiEvaluateObject)


/*******************************************************************************
 *
 * FUNCTION:    AcpiNsResolveReferences
 *
 * PARAMETERS:  Info                    - Evaluation info block
 *
 * RETURN:      Info->ReturnObject is replaced with the dereferenced object
 *
 * DESCRIPTION: Dereference certain reference objects. Called before an
 *              internal return object is converted to an external ACPI_OBJECT.
 *
 * Performs an automatic dereference of Index and RefOf reference objects.
 * These reference objects are not supported by the 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
AcpiNsResolveReferences (
    ACPI_EVALUATE_INFO      *Info)
{
    ACPI_OPERAND_OBJECT     *ObjDesc = NULL;
    ACPI_NAMESPACE_NODE     *Node;


    /* We are interested in reference objects only */

    if ((Info->ReturnObject)->Common.Type != ACPI_TYPE_LOCAL_REFERENCE)
    {
        return;
    }

    /*
     * Two types of references are supported - those created by Index and
     * RefOf operators. A name reference (AML_NAMEPATH_OP) can be converted
     * to an ACPI_OBJECT, so it is not dereferenced here. A DdbHandle
     * (AML_LOAD_OP) cannot be dereferenced, nor can it be converted to
     * an ACPI_OBJECT.
     */
    switch (Info->ReturnObject->Reference.Class)
    {
    case ACPI_REFCLASS_INDEX:

        ObjDesc = *(Info->ReturnObject->Reference.Where);
        break;

    case ACPI_REFCLASS_REFOF:

        Node = Info->ReturnObject->Reference.Object;
        if (Node)
        {
            ObjDesc = Node->Object;
        }
        break;

    default:

        return;
    }

    /* Replace the existing reference object */

    if (ObjDesc)
    {
        AcpiUtAddReference (ObjDesc);
        AcpiUtRemoveReference (Info->ReturnObject);
        Info->ReturnObject = ObjDesc;
    }

    return;
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiWalkNamespace
 *
 * PARAMETERS:  Type                - ACPI_OBJECT_TYPE to search for
 *              StartObject         - Handle in namespace where search begins
 *              MaxDepth            - Depth to which search is to reach
 *              DescendingCallback  - Called during tree descent
 *                                    when an object of "Type" is found
 *              AscendingCallback   - Called during tree ascent
 *                                    when an object of "Type" is found
 *              Context             - Passed to user function(s) above
 *              ReturnValue         - Location where return value of
 *                                    UserFunction is put if terminated early
 *
 * RETURNS      Return value from the UserFunction 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 StartHandle.
 *              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
AcpiWalkNamespace (
    ACPI_OBJECT_TYPE        Type,
    ACPI_HANDLE             StartObject,
    UINT32                  MaxDepth,
    ACPI_WALK_CALLBACK      DescendingCallback,
    ACPI_WALK_CALLBACK      AscendingCallback,
    void                    *Context,
    void                    **ReturnValue)
{
    ACPI_STATUS             Status;


    ACPI_FUNCTION_TRACE (AcpiWalkNamespace);


    /* Parameter validation */

    if ((Type > ACPI_TYPE_LOCAL_MAX) ||
        (!MaxDepth)                  ||
        (!DescendingCallback && !AscendingCallback))
    {
        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 = AcpiUtAcquireReadLock (&AcpiGbl_NamespaceRwLock);
    if (ACPI_FAILURE (Status))
    {
        return_ACPI_STATUS (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 = AcpiUtAcquireMutex (ACPI_MTX_NAMESPACE);
    if (ACPI_FAILURE (Status))
    {
        goto UnlockAndExit;
    }

    /* Now we can validate the starting node */

    if (!AcpiNsValidateHandle (StartObject))
    {
        Status = AE_BAD_PARAMETER;
        goto UnlockAndExit2;
    }

    Status = AcpiNsWalkNamespace (Type, StartObject, MaxDepth,
                ACPI_NS_WALK_UNLOCK, DescendingCallback,
                AscendingCallback, Context, ReturnValue);

UnlockAndExit2:
    (void) AcpiUtReleaseMutex (ACPI_MTX_NAMESPACE);

UnlockAndExit:
    (void) AcpiUtReleaseReadLock (&AcpiGbl_NamespaceRwLock);
    return_ACPI_STATUS (Status);
}

ACPI_EXPORT_SYMBOL (AcpiWalkNamespace)


/*******************************************************************************
 *
 * FUNCTION:    AcpiNsGetDeviceCallback
 *
 * PARAMETERS:  Callback from AcpiGetDevice
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Takes callbacks from WalkNamespace and filters out all non-
 *              present devices, or if they specified a HID, it filters based
 *              on that.
 *
 ******************************************************************************/

static ACPI_STATUS
AcpiNsGetDeviceCallback (
    ACPI_HANDLE             ObjHandle,
    UINT32                  NestingLevel,
    void                    *Context,
    void                    **ReturnValue)
{
    ACPI_GET_DEVICES_INFO   *Info = Context;
    ACPI_STATUS             Status;
    ACPI_NAMESPACE_NODE     *Node;
    UINT32                  Flags;
    ACPI_PNP_DEVICE_ID      *Hid;
    ACPI_PNP_DEVICE_ID_LIST *Cid;
    UINT32                  i;
    BOOLEAN                 Found;
    int                     NoMatch;


    Status = AcpiUtAcquireMutex (ACPI_MTX_NAMESPACE);
    if (ACPI_FAILURE (Status))
    {
        return (Status);
    }

    Node = AcpiNsValidateHandle (ObjHandle);
    Status = AcpiUtReleaseMutex (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 = AcpiUtExecute_HID (Node, &Hid);
        if (Status == AE_NOT_FOUND)
        {
            return (AE_OK);
        }
        else if (ACPI_FAILURE (Status))
        {
            return (AE_CTRL_DEPTH);
        }

        NoMatch = ACPI_STRCMP (Hid->String, Info->Hid);
        ACPI_FREE (Hid);

        if (NoMatch)
        {
            /*
             * HID does not match, attempt match within the
             * list of Compatible IDs (CIDs)
             */
            Status = AcpiUtExecute_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 = FALSE;
            for (i = 0; i < Cid->Count; i++)
            {
                if (ACPI_STRCMP (Cid->Ids[i].String, Info->Hid) == 0)
                {
                    /* Found a matching CID */

                    Found = TRUE;
                    break;
                }
            }

            ACPI_FREE (Cid);
            if (!Found)
            {
                return (AE_OK);
            }
        }
    }

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

    Status = AcpiUtExecute_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->UserFunction (ObjHandle, NestingLevel, Info->Context,
                ReturnValue);
    return (Status);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiGetDevices
 *
 * PARAMETERS:  HID                 - HID to search for. Can be NULL.
 *              UserFunction        - Called when a matching object is found
 *              Context             - Passed to user function
 *              ReturnValue         - Location where return value of
 *                                    UserFunction is put if terminated early
 *
 * RETURNS      Return value from the UserFunction 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 StartHandle.
 *              The UserFunction 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 WalkNamespace, but the callback performs
 *              additional filtering. Please see AcpiNsGetDeviceCallback.
 *
 ******************************************************************************/

ACPI_STATUS
AcpiGetDevices (
    char                    *HID,
    ACPI_WALK_CALLBACK      UserFunction,
    void                    *Context,
    void                    **ReturnValue)
{
    ACPI_STATUS             Status;
    ACPI_GET_DEVICES_INFO   Info;


    ACPI_FUNCTION_TRACE (AcpiGetDevices);


    /* Parameter validation */

    if (!UserFunction)
    {
        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.UserFunction = UserFunction;

    /*
     * 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 = AcpiUtAcquireMutex (ACPI_MTX_NAMESPACE);
    if (ACPI_FAILURE (Status))
    {
        return_ACPI_STATUS (Status);
    }

    Status = AcpiNsWalkNamespace (ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
                ACPI_UINT32_MAX, ACPI_NS_WALK_UNLOCK,
                AcpiNsGetDeviceCallback, NULL, &Info, ReturnValue);

    (void) AcpiUtReleaseMutex (ACPI_MTX_NAMESPACE);
    return_ACPI_STATUS (Status);
}

ACPI_EXPORT_SYMBOL (AcpiGetDevices)


/*******************************************************************************
 *
 * FUNCTION:    AcpiAttachData
 *
 * PARAMETERS:  ObjHandle           - 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
AcpiAttachData (
    ACPI_HANDLE             ObjHandle,
    ACPI_OBJECT_HANDLER     Handler,
    void                    *Data)
{
    ACPI_NAMESPACE_NODE     *Node;
    ACPI_STATUS             Status;


    /* Parameter validation */

    if (!ObjHandle  ||
        !Handler    ||
        !Data)
    {
        return (AE_BAD_PARAMETER);
    }

    Status = AcpiUtAcquireMutex (ACPI_MTX_NAMESPACE);
    if (ACPI_FAILURE (Status))
    {
        return (Status);
    }

    /* Convert and validate the handle */

    Node = AcpiNsValidateHandle (ObjHandle);
    if (!Node)
    {
        Status = AE_BAD_PARAMETER;
        goto UnlockAndExit;
    }

    Status = AcpiNsAttachData (Node, Handler, Data);

UnlockAndExit:
    (void) AcpiUtReleaseMutex (ACPI_MTX_NAMESPACE);
    return (Status);
}

ACPI_EXPORT_SYMBOL (AcpiAttachData)


/*******************************************************************************
 *
 * FUNCTION:    AcpiDetachData
 *
 * PARAMETERS:  ObjHandle           - Namespace node handle
 *              Handler             - Handler used in call to AcpiAttachData
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Remove data that was previously attached to a node.
 *
 ******************************************************************************/

ACPI_STATUS
AcpiDetachData (
    ACPI_HANDLE             ObjHandle,
    ACPI_OBJECT_HANDLER     Handler)
{
    ACPI_NAMESPACE_NODE     *Node;
    ACPI_STATUS             Status;


    /* Parameter validation */

    if (!ObjHandle  ||
        !Handler)
    {
        return (AE_BAD_PARAMETER);
    }

    Status = AcpiUtAcquireMutex (ACPI_MTX_NAMESPACE);
    if (ACPI_FAILURE (Status))
    {
        return (Status);
    }

    /* Convert and validate the handle */

    Node = AcpiNsValidateHandle (ObjHandle);
    if (!Node)
    {
        Status = AE_BAD_PARAMETER;
        goto UnlockAndExit;
    }

    Status = AcpiNsDetachData (Node, Handler);

UnlockAndExit:
    (void) AcpiUtReleaseMutex (ACPI_MTX_NAMESPACE);
    return (Status);
}

ACPI_EXPORT_SYMBOL (AcpiDetachData)


/*******************************************************************************
 *
 * FUNCTION:    AcpiGetData
 *
 * PARAMETERS:  ObjHandle           - Namespace node
 *              Handler             - Handler used in call to AttachData
 *              Data                - Where the data is returned
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Retrieve data that was previously attached to a namespace node.
 *
 ******************************************************************************/

ACPI_STATUS
AcpiGetData (
    ACPI_HANDLE             ObjHandle,
    ACPI_OBJECT_HANDLER     Handler,
    void                    **Data)
{
    ACPI_NAMESPACE_NODE     *Node;
    ACPI_STATUS             Status;


    /* Parameter validation */

    if (!ObjHandle  ||
        !Handler    ||
        !Data)
    {
        return (AE_BAD_PARAMETER);
    }

    Status = AcpiUtAcquireMutex (ACPI_MTX_NAMESPACE);
    if (ACPI_FAILURE (Status))
    {
        return (Status);
    }

    /* Convert and validate the handle */

    Node = AcpiNsValidateHandle (ObjHandle);
    if (!Node)
    {
        Status = AE_BAD_PARAMETER;
        goto UnlockAndExit;
    }

    Status = AcpiNsGetAttachedData (Node, Handler, Data);

UnlockAndExit:
    (void) AcpiUtReleaseMutex (ACPI_MTX_NAMESPACE);
    return (Status);
}

ACPI_EXPORT_SYMBOL (AcpiGetData)