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 /*******************************************************************************
  *
  * Module Name: nsxfeval - Public interfaces to the ACPI subsystem
  *                         ACPI Object evaluation interfaces
  *
  ******************************************************************************/
 
 /******************************************************************************
  *
  * 1. Copyright Notice
  *
  * Some or all of this work - Copyright (c) 1999 - 2024, Intel Corp.
  * All rights reserved.
  *
  * 2. License
  *
  * 2.1. This is your license from Intel Corp. under its intellectual property
  * rights. You may have additional license terms from the party that provided
  * you this software, covering your right to use that party's intellectual
  * property rights.
  *
  * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
  * copy of the source code appearing in this file ("Covered Code") an
  * irrevocable, perpetual, worldwide license under Intel's copyrights in the
  * base code distributed originally by Intel ("Original Intel Code") to copy,
  * make derivatives, distribute, use and display any portion of the Covered
  * Code in any form, with the right to sublicense such rights; and
  *
  * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
  * license (with the right to sublicense), under only those claims of Intel
  * patents that are infringed by the Original Intel Code, to make, use, sell,
  * offer to sell, and import the Covered Code and derivative works thereof
  * solely to the minimum extent necessary to exercise the above copyright
  * license, and in no event shall the patent license extend to any additions
  * to or modifications of the Original Intel Code. No other license or right
  * is granted directly or by implication, estoppel or otherwise;
  *
  * The above copyright and patent license is granted only if the following
  * conditions are met:
  *
  * 3. Conditions
  *
  * 3.1. Redistribution of Source with Rights to Further Distribute Source.
  * Redistribution of source code of any substantial portion of the Covered
  * Code or modification with rights to further distribute source must include
  * the above Copyright Notice, the above License, this list of Conditions,
  * and the following Disclaimer and Export Compliance provision. In addition,
  * Licensee must cause all Covered Code to which Licensee contributes to
  * contain a file documenting the changes Licensee made to create that Covered
  * Code and the date of any change. Licensee must include in that file the
  * documentation of any changes made by any predecessor Licensee. Licensee
  * must include a prominent statement that the modification is derived,
  * directly or indirectly, from Original Intel Code.
  *
  * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
  * Redistribution of source code of any substantial portion of the Covered
  * Code or modification without rights to further distribute source must
  * include the following Disclaimer and Export Compliance provision in the
  * documentation and/or other materials provided with distribution. In
  * addition, Licensee may not authorize further sublicense of source of any
  * portion of the Covered Code, and must include terms to the effect that the
  * license from Licensee to its licensee is limited to the intellectual
  * property embodied in the software Licensee provides to its licensee, and
  * not to intellectual property embodied in modifications its licensee may
  * make.
  *
  * 3.3. Redistribution of Executable. Redistribution in executable form of any
  * substantial portion of the Covered Code or modification must reproduce the
  * above Copyright Notice, and the following Disclaimer and Export Compliance
  * provision in the documentation and/or other materials provided with the
  * distribution.
  *
  * 3.4. Intel retains all right, title, and interest in and to the Original
  * Intel Code.
  *
  * 3.5. Neither the name Intel nor any other trademark owned or controlled by
  * Intel shall be used in advertising or otherwise to promote the sale, use or
  * other dealings in products derived from or relating to the Covered Code
  * without prior written authorization from Intel.
  *
  * 4. Disclaimer and Export Compliance
  *
  * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
  * HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
  * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE,
  * INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY
  * UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY
  * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
  * PARTICULAR PURPOSE.
  *
  * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
  * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
  * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
  * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
  * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
  * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS
  * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
  * LIMITED REMEDY.
  *
  * 4.3. Licensee shall not export, either directly or indirectly, any of this
  * software or system incorporating such software without first obtaining any
  * required license or other approval from the U. S. Department of Commerce or
  * any other agency or department of the United States Government. In the
  * event Licensee exports any such software from the United States or
  * re-exports any such software from a foreign destination, Licensee shall
  * ensure that the distribution and export/re-export of the software is in
  * compliance with all laws, regulations, orders, or other restrictions of the
  * U.S. Export Administration Regulations. Licensee agrees that neither it nor
  * any of its subsidiaries will export/re-export any technical data, process,
  * software, or service, directly or indirectly, to any country for which the
  * United States government or any agency thereof requires an export license,
  * other governmental approval, or letter of assurance, without first obtaining
  * such license, approval or letter.
  *
  *****************************************************************************
  *
  * Alternatively, you may choose to be licensed under the terms of the
  * following license:
  *
  * 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.
  *
  * 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 MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * 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 DAMAGE.
  *
  * Alternatively, you may choose to be licensed under the terms of the
  * GNU General Public License ("GPL") version 2 as published by the Free
  * Software Foundation.
  *
  *****************************************************************************/
 
 #define EXPORT_ACPI_INTERFACES
 
 #include "acpi.h"
 #include "accommon.h"
 #include "acnamesp.h"
 #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 a method,
  *                                    terminated by NULL. May be NULL
  *                                    if no parameters are being passed.
  *              ReturnBuffer        - Where to put the object return value (if
  *                                    any). Required.
  *              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_HANDLE             TargetHandle;
     char                    *FullPathname;
 
 
     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;
     }
 
     /* Get a handle here, in order to build an error message if needed */
 
     TargetHandle = Handle;
     if (Pathname)
     {
         Status = AcpiGetHandle (Handle, Pathname, &TargetHandle);
         if (ACPI_FAILURE (Status))
         {
             return_ACPI_STATUS (Status);
         }
     }
 
     FullPathname = AcpiNsGetExternalPathname (TargetHandle);
     if (!FullPathname)
     {
         return_ACPI_STATUS (AE_NO_MEMORY);
     }
 
     /* Evaluate the object */
 
     Status = AcpiEvaluateObject (TargetHandle, NULL, ExternalParams,
         ReturnBuffer);
     if (ACPI_FAILURE (Status))
     {
         goto Exit;
     }
 
     /* Type ANY means "don't care about return value type" */
 
     if (ReturnType == ACPI_TYPE_ANY)
     {
         goto Exit;
     }
 
     if (ReturnBuffer->Length == 0)
     {
         /* Error because caller specifically asked for a return value */
 
         ACPI_ERROR ((AE_INFO, "%s did not return any object",
             FullPathname));
         Status = AE_NULL_OBJECT;
         goto Exit;
     }
 
     /* Examine the object type returned from EvaluateObject */
 
     if (((ACPI_OBJECT *) ReturnBuffer->Pointer)->Type == ReturnType)
     {
         goto Exit;
     }
 
     /* Return object type does not match requested type */
 
     ACPI_ERROR ((AE_INFO,
         "Incorrect return type from %s - received [%s], requested [%s]",
         FullPathname,
         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;
     Status = AE_TYPE;
 
 Exit:
     ACPI_FREE (FullPathname);
     return_ACPI_STATUS (Status);
 }
 
 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;
     }
 
 
 #ifdef _FUTURE_FEATURE
 
     /*
      * 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)
     {
         goto CleanupReturnObject;
     }
 
     if (!Info->ReturnObject)
     {
         ReturnBuffer->Length = 0;
         goto Cleanup;
     }
 
     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_FAILURE (Status))
     {
         goto CleanupReturnObject;
     }
 
     /* 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);
         }
     }
 
 CleanupReturnObject:
 
     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 = 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 (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)

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