sys/external/bsd/acpica/dist/events/evgpeinit.c
author christos <christos@NetBSD.org>
Mon, 13 Apr 2015 17:21:01 +0000
branchtrunk
changeset 234620 e7ce51fddfdc
parent 231105 8269c5c355ca
child 237198 b816d1d365c1
permissions -rw-r--r--
---------------------------------------- 10 April 2015. Summary of changes for version 20150410: Reverted a change introduced in version 20150408 that caused a regression in the disassembler where incorrect operator symbols could be emitted. ---------------------------------------- 08 April 2015. Summary of changes for version 20150408: 1) ACPICA kernel-resident subsystem: Permanently set the return value for the _REV predefined name. It now returns 2 (was 5). This matches other ACPI implementations. _REV will be deprecated in the future, and is now defined to be 1 for ACPI 1.0, and 2 for ACPI 2.0 and later. It should never be used to differentiate or identify operating systems. Added the "Windows 2015" string to the _OSI support. ACPICA will now return TRUE to a query with this string. Fixed several issues with the local version of the printf function. Added the C99 compiler option (-std=c99) to the Unix makefiles. Current Release: Non-Debug Version: 99.9K Code, 27.4K Data, 127.3K Total Debug Version: 195.2K Code, 80.7K Data, 275.9K Total Previous Release: Non-Debug Version: 98.8K Code, 27.3K Data, 126.1K Total Debug Version: 192.1K Code, 79.8K Data, 271.9K Total 2) iASL Compiler/Disassembler and Tools: iASL: Implemented an enhancement to the constant folding feature to transform the parse tree to a simple Store operation whenever possible: Add (2, 3, X) ==> is converted to: Store (5, X) X = 2 + 3 ==> is converted to: Store (5, X) Updated support for the SLIC table (Software Licensing Description Table) in both the Data Table compiler and the disassembler. The SLIC table support now conforms to "Microsoft Software Licensing Tables (SLIC and MSDM). November 29, 2011. Copyright 2011 Microsoft". Note: Any SLIC data following the ACPI header is now defined to be "Proprietary Data", and as such, can only be entered or displayed as a hex data block. Implemented full support for the MSDM table as described in the document above. Note: The format of MSDM is similar to SLIC. Any MSDM data following the ACPI header is defined to be "Proprietary Data", and can only be entered or displayed as a hex data block. Implemented the -Pn option for the iASL Table Compiler (was only implemented for the ASL compiler). This option disables the iASL preprocessor. Disassembler: For disassembly of Data Tables, added a comment field around the Ascii equivalent data that is emitted as part of the "Raw Table Data" block. This prevents the iASL Preprocessor from possible confusion if/when the table is compiled. Disassembler: Added an option (-df) to force the disassembler to assume that the table being disassembled contains valid AML. This feature is useful for disassembling AML files that contain ACPI signatures other than DSDT or SSDT (such as OEMx or other signatures). Changes for the EFI version of the tools: 1) Fixed a build error/issue 2) Fixed a cast warning iASL: Fixed a path issue with the __FILE__ operator by making the directory prefix optional within the internal SplitInputFilename function. Debugger: Removed some unused global variables. Tests: Updated the makefile for proper generation of the AAPITS suite. ---------------------------------------- 04 February 2015. Summary of changes for version 20150204: ACPICA kernel-resident subsystem: Updated all ACPICA copyrights and signons to 2014. Added the 2014 copyright to all module headers and signons, including the standard Linux header. This affects virtually every file in the ACPICA core subsystem, iASL compiler, all ACPICA utilities, and the test suites. Events: Introduce ACPI_GPE_DISPATCH_RAW_HANDLER to fix GPE storm issues. A raw gpe handling mechanism was created to allow better handling of GPE storms that aren't easily managed by the normal handler. The raw handler allows disabling/renabling of the the GPE so that interrupt storms can be avoided in cases where events cannot be timely serviced. In this scenario, handlers should use the AcpiSetGpe() API to disable/enable the GPE. This API will leave the reference counts undisturbed, thereby preventing unintentional clearing of the GPE when the intent in only to temporarily disable it. Raw handlers allow enabling and disabling of a GPE by removing GPE register locking. As such, raw handlers much provide their own locks while using GPE API's to protect access to GPE data structures. Lv Zheng Events: Always modify GPE registers under the GPE lock. Applies GPE lock around AcpiFinishGpe() to protect access to GPE register values. Reported as bug by joe.liu@apple.com. Unix makefiles: Separate option to disable optimizations and _FORTIFY_SOURCE. This change removes the _FORTIFY_SOURCE flag from the NOOPT disable option and creates a separate flag (NOFORTIFY) for this purpose. Some toolchains may define _FORTIFY_SOURCE which leads redefined errors when building ACPICA. This allows disabling the option without also having to disable optimazations. David Box Current Release: Non-Debug Version: 101.7K Code, 27.9K Data, 129.6K Total Debug Version: 199.2K Code, 82.4K Data, 281.6K Total ---------------------------------------- 07 November 2014. Summary of changes for version 20141107: This release is available at https://acpica.org/downloads This release introduces and implements language extensions to ASL that provide support for symbolic ("C-style") operators and expressions. These language extensions are known collectively as ASL+. 1) iASL Compiler/Disassembler and Tools: Disassembler: Fixed a problem with disassembly of the UartSerialBus macro. Changed "StopBitsNone" to the correct "StopBitsZero". David E. Box. Disassembler: Fixed the Unicode macro support to add escape sequences. All non-printable ASCII values are emitted as escape sequences, as well as the standard escapes for quote and backslash. Ensures that the disassembled macro can be correctly recompiled. iASL: Added Printf/Fprintf macros for formatted output. These macros are translated to existing AML Concatenate and Store operations. Printf writes to the ASL Debug object. Fprintf allows the specification of an ASL name as the target. Only a single format specifier is required, %o, since the AML interpreter dynamically converts objects to the required type. David E. Box. (old) Store (Concatenate (Concatenate (Concatenate (Concatenate (Concatenate (Concatenate (Concatenate ("", Arg0), ": Unexpected value for "), Arg1), ", "), Arg2), " at line "), Arg3), Debug) (new) Printf ("%o: Unexpected value for %o, %o at line %o", Arg0, Arg1, Arg2, Arg3) (old) Store (Concatenate (Concatenate (Concatenate (Concatenate ("", Arg1), ": "), Arg0), " Successful"), STR1) (new) Fprintf (STR1, "%o: %o Successful", Arg1, Arg0) iASL: Added debug options (-bp, -bt) to dynamically prune levels of the ASL parse tree before the AML code is generated. This allows blocks of ASL code to be removed in order to help locate and identify problem devices and/or code. David E. Box. AcpiExec: Added support (-fi) for an optional namespace object initialization file. This file specifies initial values for namespace objects as necessary for debugging and testing different ASL code paths that may be taken as a result of BIOS options. 2) Overview of symbolic operator support for ASL (ASL+) ------------------------------------------------------- As an extension to the ASL language, iASL implements support for symbolic (C-style) operators for math and logical expressions. This can greatly simplify ASL code as well as improve both readability and maintainability. These language extensions can exist concurrently with all legacy ASL code and expressions. The symbolic extensions are 100% compatible with existing AML interpreters, since no new AML opcodes are created. To implement the extensions, the iASL compiler transforms the symbolic expressions into the legacy ASL/AML equivalents at compile time. Full symbolic expressions are supported, along with the standard C precedence and associativity rules. Full disassembler support for the symbolic expressions is provided, and creates an automatic migration path for existing ASL code to ASL+ code via the disassembly process. By default, the disassembler now emits ASL+ code with symbolic expressions. An option (-dl) is provided to force the disassembler to emit legacy ASL code if desired. Below is the complete list of the currently supported symbolic operators with examples. See the iASL User Guide for additional information. ASL+ Syntax Legacy ASL Equivalent ----------- --------------------- // Math operators Z = X + Y Add (X, Y, Z) Z = X - Y Subtract (X, Y, Z) Z = X * Y Multiply (X, Y, Z) Z = X / Y Divide (X, Y, , Z) Z = X % Y Mod (X, Y, Z) Z = X << Y ShiftLeft (X, Y, Z) Z = X >> Y ShiftRight (X, Y, Z) Z = X & Y And (X, Y, Z) Z = X | Y Or (X, Y, Z) Z = X ^ Y Xor (X, Y, Z) Z = ~X Not (X, Z) X++ Increment (X) X-- Decrement (X) // Logical operators (X == Y) LEqual (X, Y) (X != Y) LNotEqual (X, Y) (X < Y) LLess (X, Y) (X > Y) LGreater (X, Y) (X <= Y) LLessEqual (X, Y) (X >= Y) LGreaterEqual (X, Y) (X && Y) LAnd (X, Y) (X || Y) LOr (X, Y) (!X) LNot (X) // Assignment and compound assignment operations X = Y Store (Y, X) X += Y Add (X, Y, X) X -= Y Subtract (X, Y, X) X *= Y Multiply (X, Y, X) X /= Y Divide (X, Y, , X) X %= Y Mod (X, Y, X) X <<= Y ShiftLeft (X, Y, X) X >>= Y ShiftRight (X, Y, X) X &= Y And (X, Y, X) X |= Y Or (X, Y, X) X ^= Y Xor (X, Y, X) 3) ASL+ Examples: ----------------- Legacy ASL: If (LOr (LOr (LEqual (And (R510, 0x03FB), 0x02E0), LEqual ( And (R520, 0x03FB), 0x02E0)), LOr (LEqual (And (R530, 0x03FB), 0x02E0), LEqual (And (R540, 0x03FB), 0x02E0)))) { And (MEMB, 0xFFFFFFF0, SRMB) Store (MEMB, Local2) Store (PDBM, Local1) And (PDBM, 0xFFFFFFFFFFFFFFF9, PDBM) Store (SRMB, MEMB) Or (PDBM, 0x02, PDBM) } ASL+ version: If (((R510 & 0x03FB) == 0x02E0) || ((R520 & 0x03FB) == 0x02E0) || ((R530 & 0x03FB) == 0x02E0) || ((R540 & 0x03FB) == 0x02E0)) { SRMB = (MEMB & 0xFFFFFFF0) Local2 = MEMB Local1 = PDBM PDBM &= 0xFFFFFFFFFFFFFFF9 MEMB = SRMB PDBM |= 0x02 } Legacy ASL: Store (0x1234, Local1) Multiply (Add (Add (Local1, TEST), 0x20), Local2, Local3) Multiply (Local2, Add (Add (Local1, TEST), 0x20), Local3) Add (Local1, Add (TEST, Multiply (0x20, Local2)), Local3) Store (Index (PKG1, 0x03), Local6) Store (Add (Local3, Local2), Debug) Add (Local1, 0x0F, Local2) Add (Local1, Multiply (Local2, Local3), Local2) Multiply (Add (Add (Local1, TEST), 0x20), ToBCD (Local1), Local3) ASL+ version: Local1 = 0x1234 Local3 = (((Local1 + TEST) + 0x20) * Local2) Local3 = (Local2 * ((Local1 + TEST) + 0x20)) Local3 = (Local1 + (TEST + (0x20 * Local2))) Local6 = Index (PKG1, 0x03) Debug = (Local3 + Local2) Local2 = (Local1 + 0x0F) Local2 = (Local1 + (Local2 * Local3)) Local3 = (((Local1 + TEST) + 0x20) * ToBCD (Local1))

/******************************************************************************
 *
 * Module Name: evgpeinit - System GPE initialization and update
 *
 *****************************************************************************/

/*
 * 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.
 */

#include "acpi.h"
#include "accommon.h"
#include "acevents.h"
#include "acnamesp.h"

#define _COMPONENT          ACPI_EVENTS
        ACPI_MODULE_NAME    ("evgpeinit")

#if (!ACPI_REDUCED_HARDWARE) /* Entire module */

/*
 * Note: History of _PRW support in ACPICA
 *
 * Originally (2000 - 2010), the GPE initialization code performed a walk of
 * the entire namespace to execute the _PRW methods and detect all GPEs
 * capable of waking the system.
 *
 * As of 10/2010, the _PRW method execution has been removed since it is
 * actually unnecessary. The host OS must in fact execute all _PRW methods
 * in order to identify the device/power-resource dependencies. We now put
 * the onus on the host OS to identify the wake GPEs as part of this process
 * and to inform ACPICA of these GPEs via the AcpiSetupGpeForWake interface. This
 * not only reduces the complexity of the ACPICA initialization code, but in
 * some cases (on systems with very large namespaces) it should reduce the
 * kernel boot time as well.
 */

/*******************************************************************************
 *
 * FUNCTION:    AcpiEvGpeInitialize
 *
 * PARAMETERS:  None
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Initialize the GPE data structures and the FADT GPE 0/1 blocks
 *
 ******************************************************************************/

ACPI_STATUS
AcpiEvGpeInitialize (
    void)
{
    UINT32                  RegisterCount0 = 0;
    UINT32                  RegisterCount1 = 0;
    UINT32                  GpeNumberMax = 0;
    ACPI_STATUS             Status;


    ACPI_FUNCTION_TRACE (EvGpeInitialize);


    ACPI_DEBUG_PRINT_RAW ((ACPI_DB_INIT,
        "Initializing General Purpose Events (GPEs):\n"));

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

    /*
     * Initialize the GPE Block(s) defined in the FADT
     *
     * Why the GPE register block lengths are divided by 2:  From the ACPI
     * Spec, section "General-Purpose Event Registers", we have:
     *
     * "Each register block contains two registers of equal length
     *  GPEx_STS and GPEx_EN (where x is 0 or 1). The length of the
     *  GPE0_STS and GPE0_EN registers is equal to half the GPE0_LEN
     *  The length of the GPE1_STS and GPE1_EN registers is equal to
     *  half the GPE1_LEN. If a generic register block is not supported
     *  then its respective block pointer and block length values in the
     *  FADT table contain zeros. The GPE0_LEN and GPE1_LEN do not need
     *  to be the same size."
     */

    /*
     * Determine the maximum GPE number for this machine.
     *
     * Note: both GPE0 and GPE1 are optional, and either can exist without
     * the other.
     *
     * If EITHER the register length OR the block address are zero, then that
     * particular block is not supported.
     */
    if (AcpiGbl_FADT.Gpe0BlockLength &&
        AcpiGbl_FADT.XGpe0Block.Address)
    {
        /* GPE block 0 exists (has both length and address > 0) */

        RegisterCount0 = (UINT16) (AcpiGbl_FADT.Gpe0BlockLength / 2);
        GpeNumberMax = (RegisterCount0 * ACPI_GPE_REGISTER_WIDTH) - 1;

        /* Install GPE Block 0 */

        Status = AcpiEvCreateGpeBlock (AcpiGbl_FadtGpeDevice,
                    AcpiGbl_FADT.XGpe0Block.Address,
                    AcpiGbl_FADT.XGpe0Block.SpaceId,
                    RegisterCount0, 0,
                    AcpiGbl_FADT.SciInterrupt, &AcpiGbl_GpeFadtBlocks[0]);

        if (ACPI_FAILURE (Status))
        {
            ACPI_EXCEPTION ((AE_INFO, Status,
                "Could not create GPE Block 0"));
        }
    }

    if (AcpiGbl_FADT.Gpe1BlockLength &&
        AcpiGbl_FADT.XGpe1Block.Address)
    {
        /* GPE block 1 exists (has both length and address > 0) */

        RegisterCount1 = (UINT16) (AcpiGbl_FADT.Gpe1BlockLength / 2);

        /* Check for GPE0/GPE1 overlap (if both banks exist) */

        if ((RegisterCount0) &&
            (GpeNumberMax >= AcpiGbl_FADT.Gpe1Base))
        {
            ACPI_ERROR ((AE_INFO,
                "GPE0 block (GPE 0 to %u) overlaps the GPE1 block "
                "(GPE %u to %u) - Ignoring GPE1",
                GpeNumberMax, AcpiGbl_FADT.Gpe1Base,
                AcpiGbl_FADT.Gpe1Base +
                ((RegisterCount1 * ACPI_GPE_REGISTER_WIDTH) - 1)));

            /* Ignore GPE1 block by setting the register count to zero */

            RegisterCount1 = 0;
        }
        else
        {
            /* Install GPE Block 1 */

            Status = AcpiEvCreateGpeBlock (AcpiGbl_FadtGpeDevice,
                        AcpiGbl_FADT.XGpe1Block.Address,
                        AcpiGbl_FADT.XGpe1Block.SpaceId,
                        RegisterCount1,
                        AcpiGbl_FADT.Gpe1Base,
                        AcpiGbl_FADT.SciInterrupt, &AcpiGbl_GpeFadtBlocks[1]);

            if (ACPI_FAILURE (Status))
            {
                ACPI_EXCEPTION ((AE_INFO, Status,
                    "Could not create GPE Block 1"));
            }

            /*
             * GPE0 and GPE1 do not have to be contiguous in the GPE number
             * space. However, GPE0 always starts at GPE number zero.
             */
            GpeNumberMax = AcpiGbl_FADT.Gpe1Base +
                            ((RegisterCount1 * ACPI_GPE_REGISTER_WIDTH) - 1);
        }
    }

    /* Exit if there are no GPE registers */

    if ((RegisterCount0 + RegisterCount1) == 0)
    {
        /* GPEs are not required by ACPI, this is OK */

        ACPI_DEBUG_PRINT ((ACPI_DB_INIT,
            "There are no GPE blocks defined in the FADT\n"));
        Status = AE_OK;
        goto Cleanup;
    }


Cleanup:
    (void) AcpiUtReleaseMutex (ACPI_MTX_NAMESPACE);
    return_ACPI_STATUS (AE_OK);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiEvUpdateGpes
 *
 * PARAMETERS:  TableOwnerId        - ID of the newly-loaded ACPI table
 *
 * RETURN:      None
 *
 * DESCRIPTION: Check for new GPE methods (_Lxx/_Exx) made available as a
 *              result of a Load() or LoadTable() operation. If new GPE
 *              methods have been installed, register the new methods.
 *
 ******************************************************************************/

void
AcpiEvUpdateGpes (
    ACPI_OWNER_ID           TableOwnerId)
{
    ACPI_GPE_XRUPT_INFO     *GpeXruptInfo;
    ACPI_GPE_BLOCK_INFO     *GpeBlock;
    ACPI_GPE_WALK_INFO      WalkInfo;
    ACPI_STATUS             Status = AE_OK;


    /*
     * Find any _Lxx/_Exx GPE methods that have just been loaded.
     *
     * Any GPEs that correspond to new _Lxx/_Exx methods are immediately
     * enabled.
     *
     * Examine the namespace underneath each GpeDevice within the
     * GpeBlock lists.
     */
    Status = AcpiUtAcquireMutex (ACPI_MTX_EVENTS);
    if (ACPI_FAILURE (Status))
    {
        return;
    }

    WalkInfo.Count = 0;
    WalkInfo.OwnerId = TableOwnerId;
    WalkInfo.ExecuteByOwnerId = TRUE;

    /* Walk the interrupt level descriptor list */

    GpeXruptInfo = AcpiGbl_GpeXruptListHead;
    while (GpeXruptInfo)
    {
        /* Walk all Gpe Blocks attached to this interrupt level */

        GpeBlock = GpeXruptInfo->GpeBlockListHead;
        while (GpeBlock)
        {
            WalkInfo.GpeBlock = GpeBlock;
            WalkInfo.GpeDevice = GpeBlock->Node;

            Status = AcpiNsWalkNamespace (ACPI_TYPE_METHOD,
                        WalkInfo.GpeDevice, ACPI_UINT32_MAX,
                        ACPI_NS_WALK_NO_UNLOCK, AcpiEvMatchGpeMethod,
                        NULL, &WalkInfo, NULL);
            if (ACPI_FAILURE (Status))
            {
                ACPI_EXCEPTION ((AE_INFO, Status,
                    "While decoding _Lxx/_Exx methods"));
            }

            GpeBlock = GpeBlock->Next;
        }

        GpeXruptInfo = GpeXruptInfo->Next;
    }

    if (WalkInfo.Count)
    {
        ACPI_INFO ((AE_INFO, "Enabled %u new GPEs", WalkInfo.Count));
    }

    (void) AcpiUtReleaseMutex (ACPI_MTX_EVENTS);
    return;
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiEvMatchGpeMethod
 *
 * PARAMETERS:  Callback from WalkNamespace
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Called from AcpiWalkNamespace. Expects each object to be a
 *              control method under the _GPE portion of the namespace.
 *              Extract the name and GPE type from the object, saving this
 *              information for quick lookup during GPE dispatch. Allows a
 *              per-OwnerId evaluation if ExecuteByOwnerId is TRUE in the
 *              WalkInfo parameter block.
 *
 *              The name of each GPE control method is of the form:
 *              "_Lxx" or "_Exx", where:
 *                  L      - means that the GPE is level triggered
 *                  E      - means that the GPE is edge triggered
 *                  xx     - is the GPE number [in HEX]
 *
 * If WalkInfo->ExecuteByOwnerId is TRUE, we only execute examine GPE methods
 * with that owner.
 *
 ******************************************************************************/

ACPI_STATUS
AcpiEvMatchGpeMethod (
    ACPI_HANDLE             ObjHandle,
    UINT32                  Level,
    void                    *Context,
    void                    **ReturnValue)
{
    ACPI_NAMESPACE_NODE     *MethodNode = ACPI_CAST_PTR (ACPI_NAMESPACE_NODE, ObjHandle);
    ACPI_GPE_WALK_INFO      *WalkInfo = ACPI_CAST_PTR (ACPI_GPE_WALK_INFO, Context);
    ACPI_GPE_EVENT_INFO     *GpeEventInfo;
    UINT32                  GpeNumber;
    char                    Name[ACPI_NAME_SIZE + 1];
    UINT8                   Type;


    ACPI_FUNCTION_TRACE (EvMatchGpeMethod);


    /* Check if requested OwnerId matches this OwnerId */

    if ((WalkInfo->ExecuteByOwnerId) &&
        (MethodNode->OwnerId != WalkInfo->OwnerId))
    {
        return_ACPI_STATUS (AE_OK);
    }

    /*
     * Match and decode the _Lxx and _Exx GPE method names
     *
     * 1) Extract the method name and null terminate it
     */
    ACPI_MOVE_32_TO_32 (Name, &MethodNode->Name.Integer);
    Name[ACPI_NAME_SIZE] = 0;

    /* 2) Name must begin with an underscore */

    if (Name[0] != '_')
    {
        return_ACPI_STATUS (AE_OK); /* Ignore this method */
    }

    /*
     * 3) Edge/Level determination is based on the 2nd character
     *    of the method name
     */
    switch (Name[1])
    {
    case 'L':

        Type = ACPI_GPE_LEVEL_TRIGGERED;
        break;

    case 'E':

        Type = ACPI_GPE_EDGE_TRIGGERED;
        break;

    default:

        /* Unknown method type, just ignore it */

        ACPI_DEBUG_PRINT ((ACPI_DB_LOAD,
            "Ignoring unknown GPE method type: %s "
            "(name not of form _Lxx or _Exx)", Name));
        return_ACPI_STATUS (AE_OK);
    }

    /* 4) The last two characters of the name are the hex GPE Number */

    GpeNumber = ACPI_STRTOUL (&Name[2], NULL, 16);
    if (GpeNumber == ACPI_UINT32_MAX)
    {
        /* Conversion failed; invalid method, just ignore it */

        ACPI_DEBUG_PRINT ((ACPI_DB_LOAD,
            "Could not extract GPE number from name: %s "
            "(name is not of form _Lxx or _Exx)", Name));
        return_ACPI_STATUS (AE_OK);
    }

    /* Ensure that we have a valid GPE number for this GPE block */

    GpeEventInfo = AcpiEvLowGetGpeInfo (GpeNumber, WalkInfo->GpeBlock);
    if (!GpeEventInfo)
    {
        /*
         * This GpeNumber is not valid for this GPE block, just ignore it.
         * However, it may be valid for a different GPE block, since GPE0
         * and GPE1 methods both appear under \_GPE.
         */
        return_ACPI_STATUS (AE_OK);
    }

    if ((ACPI_GPE_DISPATCH_TYPE (GpeEventInfo->Flags) ==
            ACPI_GPE_DISPATCH_HANDLER) ||
        (ACPI_GPE_DISPATCH_TYPE (GpeEventInfo->Flags) ==
            ACPI_GPE_DISPATCH_RAW_HANDLER))
    {
        /* If there is already a handler, ignore this GPE method */

        return_ACPI_STATUS (AE_OK);
    }

    if (ACPI_GPE_DISPATCH_TYPE (GpeEventInfo->Flags) ==
            ACPI_GPE_DISPATCH_METHOD)
    {
        /*
         * If there is already a method, ignore this method. But check
         * for a type mismatch (if both the _Lxx AND _Exx exist)
         */
        if (Type != (GpeEventInfo->Flags & ACPI_GPE_XRUPT_TYPE_MASK))
        {
            ACPI_ERROR ((AE_INFO,
                "For GPE 0x%.2X, found both _L%2.2X and _E%2.2X methods",
                GpeNumber, GpeNumber, GpeNumber));
        }
        return_ACPI_STATUS (AE_OK);
    }

    /* Disable the GPE in case it's been enabled already. */

    (void) AcpiHwLowSetGpe (GpeEventInfo, ACPI_GPE_DISABLE);

    /*
     * Add the GPE information from above to the GpeEventInfo block for
     * use during dispatch of this GPE.
     */
    GpeEventInfo->Flags &= ~(ACPI_GPE_DISPATCH_MASK);
    GpeEventInfo->Flags |= (UINT8) (Type | ACPI_GPE_DISPATCH_METHOD);
    GpeEventInfo->Dispatch.MethodNode = MethodNode;

    ACPI_DEBUG_PRINT ((ACPI_DB_LOAD,
        "Registered GPE method %s as GPE number 0x%.2X\n",
        Name, GpeNumber));
    return_ACPI_STATUS (AE_OK);
}

#endif /* !ACPI_REDUCED_HARDWARE */