exprep.c

acpi tools for linux include acpiexec and acpixtract

    case AML_FIELD_ACCESS_WORD:
        ByteAlignment = 2;
        BitLength     = 16;
        break;

    case AML_FIELD_ACCESS_DWORD:
        ByteAlignment = 4;
        BitLength     = 32;
        break;

    case AML_FIELD_ACCESS_QWORD:    /* ACPI 2.0 */
        ByteAlignment = 8;
        BitLength     = 64;
        break;

    default:
        /* Invalid field access type */

        ACPI_ERROR ((AE_INFO,
            "Unknown field access type %X",
            Access));
        return_UINT32 (0);
    }

    if (ACPI_GET_OBJECT_TYPE (ObjDesc) == ACPI_TYPE_BUFFER_FIELD)
    {
        /*
         * BufferField access can be on any byte boundary, so the
         * ByteAlignment is always 1 byte -- regardless of any ByteAlignment
         * implied by the field access type.
         */
        ByteAlignment = 1;
    }

    *ReturnByteAlignment = ByteAlignment;
    return_UINT32 (BitLength);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiExPrepCommonFieldObject
 *
 * PARAMETERS:  ObjDesc             - The field object
 *              FieldFlags          - Access, LockRule, and UpdateRule.
 *                                    The format of a FieldFlag is described
 *                                    in the ACPI specification
 *              FieldAttribute      - Special attributes (not used)
 *              FieldBitPosition    - Field start position
 *              FieldBitLength      - Field length in number of bits
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Initialize the areas of the field object that are common
 *              to the various types of fields.  Note: This is very "sensitive"
 *              code because we are solving the general case for field
 *              alignment.
 *
 ******************************************************************************/

ACPI_STATUS
AcpiExPrepCommonFieldObject (
    ACPI_OPERAND_OBJECT     *ObjDesc,
    UINT8                   FieldFlags,
    UINT8                   FieldAttribute,
    UINT32                  FieldBitPosition,
    UINT32                  FieldBitLength)
{
    UINT32                  AccessBitWidth;
    UINT32                  ByteAlignment;
    UINT32                  NearestByteAddress;


    ACPI_FUNCTION_TRACE (ExPrepCommonFieldObject);


    /*
     * Note: the structure being initialized is the
     * ACPI_COMMON_FIELD_INFO;  No structure fields outside of the common
     * area are initialized by this procedure.
     */
    ObjDesc->CommonField.FieldFlags = FieldFlags;
    ObjDesc->CommonField.Attribute  = FieldAttribute;
    ObjDesc->CommonField.BitLength  = FieldBitLength;

    /*
     * Decode the access type so we can compute offsets.  The access type gives
     * two pieces of information - the width of each field access and the
     * necessary ByteAlignment (address granularity) of the access.
     *
     * For AnyAcc, the AccessBitWidth is the largest width that is both
     * necessary and possible in an attempt to access the whole field in one
     * I/O operation.  However, for AnyAcc, the ByteAlignment is always one
     * byte.
     *
     * For all Buffer Fields, the ByteAlignment is always one byte.
     *
     * For all other access types (Byte, Word, Dword, Qword), the Bitwidth is
     * the same (equivalent) as the ByteAlignment.
     */
    AccessBitWidth = AcpiExDecodeFieldAccess (ObjDesc, FieldFlags,
                                &ByteAlignment);
    if (!AccessBitWidth)
    {
        return_ACPI_STATUS (AE_AML_OPERAND_VALUE);
    }

    /* Setup width (access granularity) fields */

    ObjDesc->CommonField.AccessByteWidth = (UINT8)
            ACPI_DIV_8 (AccessBitWidth);            /* 1,  2,  4,  8 */

    ObjDesc->CommonField.AccessBitWidth = (UINT8) AccessBitWidth;

    /*
     * BaseByteOffset is the address of the start of the field within the
     * region.  It is the byte address of the first *datum* (field-width data
     * unit) of the field. (i.e., the first datum that contains at least the
     * first *bit* of the field.)
     *
     * Note: ByteAlignment is always either equal to the AccessBitWidth or 8
     * (Byte access), and it defines the addressing granularity of the parent
     * region or buffer.
     */
    NearestByteAddress =
            ACPI_ROUND_BITS_DOWN_TO_BYTES (FieldBitPosition);
    ObjDesc->CommonField.BaseByteOffset = (UINT32)
            ACPI_ROUND_DOWN (NearestByteAddress, ByteAlignment);

    /*
     * StartFieldBitOffset is the offset of the first bit of the field within
     * a field datum.
     */
    ObjDesc->CommonField.StartFieldBitOffset = (UINT8)
        (FieldBitPosition - ACPI_MUL_8 (ObjDesc->CommonField.BaseByteOffset));

    /*
     * Does the entire field fit within a single field access element? (datum)
     * (i.e., without crossing a datum boundary)
     */
    if ((ObjDesc->CommonField.StartFieldBitOffset + FieldBitLength) <=
            (UINT16) AccessBitWidth)
    {
        ObjDesc->Common.Flags |= AOPOBJ_SINGLE_DATUM;
    }

    return_ACPI_STATUS (AE_OK);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiExPrepFieldValue
 *
 * PARAMETERS:  Info    - Contains all field creation info
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Construct an ACPI_OPERAND_OBJECT of type DefField and
 *              connect it to the parent Node.
 *
 ******************************************************************************/

ACPI_STATUS
AcpiExPrepFieldValue (
    ACPI_CREATE_FIELD_INFO  *Info)
{
    ACPI_OPERAND_OBJECT     *ObjDesc;
    ACPI_OPERAND_OBJECT     *SecondDesc = NULL;
    UINT32                  Type;
    ACPI_STATUS             Status;


    ACPI_FUNCTION_TRACE (ExPrepFieldValue);


    /* Parameter validation */

    if (Info->FieldType != ACPI_TYPE_LOCAL_INDEX_FIELD)
    {
        if (!Info->RegionNode)
        {
            ACPI_ERROR ((AE_INFO, "Null RegionNode"));
            return_ACPI_STATUS (AE_AML_NO_OPERAND);
        }

        Type = AcpiNsGetType (Info->RegionNode);
        if (Type != ACPI_TYPE_REGION)
        {
            ACPI_ERROR ((AE_INFO,
                "Needed Region, found type %X (%s)",
                Type, AcpiUtGetTypeName (Type)));

            return_ACPI_STATUS (AE_AML_OPERAND_TYPE);
        }
    }

    /* Allocate a new field object */

    ObjDesc = AcpiUtCreateInternalObject (Info->FieldType);
    if (!ObjDesc)
    {
        return_ACPI_STATUS (AE_NO_MEMORY);
    }

    /* Initialize areas of the object that are common to all fields */

    ObjDesc->CommonField.Node = Info->FieldNode;
    Status = AcpiExPrepCommonFieldObject (ObjDesc, Info->FieldFlags,
                Info->Attribute, Info->FieldBitPosition, Info->FieldBitLength);
    if (ACPI_FAILURE (Status))
    {
        AcpiUtDeleteObjectDesc (ObjDesc);
        return_ACPI_STATUS (Status);
    }

    /* Initialize areas of the object that are specific to the field type */

    switch (Info->FieldType)
    {
    case ACPI_TYPE_LOCAL_REGION_FIELD:

        ObjDesc->Field.RegionObj = AcpiNsGetAttachedObject (Info->RegionNode);

        /* An additional reference for the container */

        AcpiUtAddReference (ObjDesc->Field.RegionObj);

        ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
            "RegionField: BitOff %X, Off %X, Gran %X, Region %p\n",
            ObjDesc->Field.StartFieldBitOffset, ObjDesc->Field.BaseByteOffset,
            ObjDesc->Field.AccessByteWidth, ObjDesc->Field.RegionObj));
        break;


    case ACPI_TYPE_LOCAL_BANK_FIELD:

        ObjDesc->BankField.Value     = Info->BankValue;
        ObjDesc->BankField.RegionObj = AcpiNsGetAttachedObject (
                                            Info->RegionNode);
        ObjDesc->BankField.BankObj   = AcpiNsGetAttachedObject (
                                            Info->RegisterNode);

        /* An additional reference for the attached objects */

        AcpiUtAddReference (ObjDesc->BankField.RegionObj);
        AcpiUtAddReference (ObjDesc->BankField.BankObj);

        ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
            "Bank Field: BitOff %X, Off %X, Gran %X, Region %p, BankReg %p\n",
            ObjDesc->BankField.StartFieldBitOffset,
            ObjDesc->BankField.BaseByteOffset,
            ObjDesc->Field.AccessByteWidth,
            ObjDesc->BankField.RegionObj,
            ObjDesc->BankField.BankObj));

        /*
         * Remember location in AML stream of the field unit
         * opcode and operands -- since the BankValue
         * operands must be evaluated.
         */
        SecondDesc                  = ObjDesc->Common.NextObject;
        SecondDesc->Extra.AmlStart  = ((ACPI_PARSE_OBJECT*) (Info->DataRegisterNode))->Named.Data;
        SecondDesc->Extra.AmlLength = ((ACPI_PARSE_OBJECT*) (Info->DataRegisterNode))->Named.Length;

        break;


    case ACPI_TYPE_LOCAL_INDEX_FIELD:

        /* Get the Index and Data registers */

        ObjDesc->IndexField.IndexObj = AcpiNsGetAttachedObject (
                                            Info->RegisterNode);
        ObjDesc->IndexField.DataObj  = AcpiNsGetAttachedObject (
                                            Info->DataRegisterNode);

        if (!ObjDesc->IndexField.DataObj || !ObjDesc->IndexField.IndexObj)
        {
            ACPI_ERROR ((AE_INFO, "Null Index Object during field prep"));
            AcpiUtDeleteObjectDesc (ObjDesc);
            return_ACPI_STATUS (AE_AML_INTERNAL);
        }

        /* An additional reference for the attached objects */

        AcpiUtAddReference (ObjDesc->IndexField.DataObj);
        AcpiUtAddReference (ObjDesc->IndexField.IndexObj);

        /*
         * April 2006: Changed to match MS behavior
         *
         * The value written to the Index register is the byte offset of the
         * target field in units of the granularity of the IndexField
         *
         * Previously, the value was calculated as an index in terms of the
         * width of the Data register, as below:
         *
         *      ObjDesc->IndexField.Value = (UINT32)
         *          (Info->FieldBitPosition / ACPI_MUL_8 (
         *              ObjDesc->Field.AccessByteWidth));
         *
         * February 2006: Tried value as a byte offset:
         *      ObjDesc->IndexField.Value = (UINT32)
         *          ACPI_DIV_8 (Info->FieldBitPosition);
         */
        ObjDesc->IndexField.Value = (UINT32) ACPI_ROUND_DOWN (
            ACPI_DIV_8 (Info->FieldBitPosition),
            ObjDesc->IndexField.AccessByteWidth);

        ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
            "IndexField: BitOff %X, Off %X, Value %X, Gran %X, Index %p, Data %p\n",
            ObjDesc->IndexField.StartFieldBitOffset,
            ObjDesc->IndexField.BaseByteOffset,
            ObjDesc->IndexField.Value,
            ObjDesc->Field.AccessByteWidth,
            ObjDesc->IndexField.IndexObj,
            ObjDesc->IndexField.DataObj));
        break;

    default:
        /* No other types should get here */
        break;
    }

    /*
     * Store the constructed descriptor (ObjDesc) into the parent Node,
     * preserving the current type of that NamedObj.
     */
    Status = AcpiNsAttachObject (Info->FieldNode, ObjDesc,
                    AcpiNsGetType (Info->FieldNode));

    ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD, "Set NamedObj %p [%4.4s], ObjDesc %p\n",
            Info->FieldNode, AcpiUtGetNodeName (Info->FieldNode), ObjDesc));

    /* Remove local reference to the object */

    AcpiUtRemoveReference (ObjDesc);
    return_ACPI_STATUS (Status);
}