freebsd-dev/sys/contrib/dev/acpica/exfldio.c

/******************************************************************************
 *
 * Module Name: exfldio - Aml Field I/O
 *              $Revision: 62 $
 *
 *****************************************************************************/

/******************************************************************************
 *
 * 1. Copyright Notice
 *
 * Some or all of this work - Copyright (c) 1999, 2000, 2001, 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.
 *
 *****************************************************************************/


#define __EXFLDIO_C__

#include "acpi.h"
#include "acinterp.h"
#include "amlcode.h"
#include "acnamesp.h"
#include "achware.h"
#include "acevents.h"
#include "acdispat.h"


#define _COMPONENT          ACPI_EXECUTER
        MODULE_NAME         ("exfldio")


/*******************************************************************************
 *
 * FUNCTION:    AcpiExSetupField
 *
 * PARAMETERS:  *ObjDesc            - Field to be read or written
 *              FieldDatumByteOffset     - Current offset into the field
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Common processing for AcpiExExtractFromField and
 *              AcpiExInsertIntoField
 *
 ******************************************************************************/

ACPI_STATUS
AcpiExSetupField (
    ACPI_OPERAND_OBJECT     *ObjDesc,
    UINT32                  FieldDatumByteOffset)
{
    ACPI_STATUS             Status = AE_OK;
    ACPI_OPERAND_OBJECT     *RgnDesc;


    FUNCTION_TRACE_U32 ("ExSetupField", FieldDatumByteOffset);

    RgnDesc = ObjDesc->CommonField.RegionObj;

    if (ACPI_TYPE_REGION != RgnDesc->Common.Type)
    {
        ACPI_DEBUG_PRINT ((ACPI_DB_ERROR, "Needed Region, found type %x %s\n",
            RgnDesc->Common.Type, AcpiUtGetTypeName (RgnDesc->Common.Type)));
        return_ACPI_STATUS (AE_AML_OPERAND_TYPE);
    }


    /*
     * If the Region Address and Length have not been previously evaluated,
     * evaluate them now and save the results.
     */
    if (!(RgnDesc->Region.Flags & AOPOBJ_DATA_VALID))
    {

        Status = AcpiDsGetRegionArguments (RgnDesc);
        if (ACPI_FAILURE (Status))
        {
            return_ACPI_STATUS (Status);
        }
    }


    /*
     * Validate the request.  The entire request from the byte offset for a
     * length of one field datum (access width) must fit within the region.
     * (Region length is specified in bytes)
     */
    if (RgnDesc->Region.Length < (ObjDesc->CommonField.BaseByteOffset +
                                    FieldDatumByteOffset +
                                    ObjDesc->CommonField.AccessByteWidth))
    {
        if (RgnDesc->Region.Length < ObjDesc->CommonField.AccessByteWidth)
        {
            /* 
             * This is the case where the AccessType (AccWord, etc.) is wider
             * than the region itself.  For example, a region of length one
             * byte, and a field with Dword access specified.
             */
            ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
                "Field access width (%d bytes) too large for region size (%X)\n",
                ObjDesc->CommonField.AccessByteWidth, RgnDesc->Region.Length));
        }

        /*
         * Offset rounded up to next multiple of field width
         * exceeds region length, indicate an error
         */
        ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
            "Field base+offset+width %X+%X+%X exceeds region size (%X bytes) field=%p region=%p\n",
            ObjDesc->CommonField.BaseByteOffset, FieldDatumByteOffset, 
            ObjDesc->CommonField.AccessByteWidth,
            RgnDesc->Region.Length, ObjDesc, RgnDesc));

        return_ACPI_STATUS (AE_AML_REGION_LIMIT);
    }

    return_ACPI_STATUS (AE_OK);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiExReadFieldDatum
 *
 * PARAMETERS:  *ObjDesc            - Field to be read
 *              *Value              - Where to store value (must be 32 bits)
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Retrieve the value of the given field
 *
 ******************************************************************************/

ACPI_STATUS
AcpiExReadFieldDatum (
    ACPI_OPERAND_OBJECT     *ObjDesc,
    UINT32                  FieldDatumByteOffset,
    UINT32                  *Value)
{
    ACPI_STATUS             Status;
    ACPI_OPERAND_OBJECT     *RgnDesc;
    ACPI_PHYSICAL_ADDRESS   Address;
    UINT32                  LocalValue;


    FUNCTION_TRACE_U32 ("ExReadFieldDatum", FieldDatumByteOffset);


    if (!Value)
    {
        LocalValue = 0;
        Value = &LocalValue;    /*  support reads without saving value  */
    }

    /* Clear the entire return buffer first, [Very Important!] */

    *Value = 0;


    /*
     * BufferFields - Read from a Buffer
     * Other Fields - Read from a Operation Region.
     */
    switch (ObjDesc->Common.Type)
    {
    case ACPI_TYPE_BUFFER_FIELD:

        /*
         * For BufferFields, we only need to copy the data from the
         * source buffer.  Length is the field width in bytes.
         */
        MEMCPY (Value, (ObjDesc->BufferField.BufferObj)->Buffer.Pointer
                        + ObjDesc->BufferField.BaseByteOffset + FieldDatumByteOffset,
                        ObjDesc->CommonField.AccessByteWidth);
        Status = AE_OK;
        break;


    case INTERNAL_TYPE_REGION_FIELD:
    case INTERNAL_TYPE_BANK_FIELD:

        /*
         * For other fields, we need to go through an Operation Region
         * (Only types that will get here are RegionFields and BankFields)
         */
        Status = AcpiExSetupField (ObjDesc, FieldDatumByteOffset);
        if (ACPI_FAILURE (Status))
        {
            return_ACPI_STATUS (Status);
        }


        /*
         * The physical address of this field datum is:
         *
         * 1) The base of the region, plus
         * 2) The base offset of the field, plus
         * 3) The current offset into the field
         */
        RgnDesc = ObjDesc->CommonField.RegionObj;
        Address = RgnDesc->Region.Address + ObjDesc->CommonField.BaseByteOffset +
                    FieldDatumByteOffset;

        ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD, "Region %s(%X) width %X base:off %X:%X at %8.8lX%8.8lX\n",
            AcpiUtGetRegionName (RgnDesc->Region.SpaceId),
            RgnDesc->Region.SpaceId, ObjDesc->CommonField.AccessBitWidth,
            ObjDesc->CommonField.BaseByteOffset, FieldDatumByteOffset,
            HIDWORD(Address), LODWORD(Address)));


        /* Invoke the appropriate AddressSpace/OpRegion handler */

        Status = AcpiEvAddressSpaceDispatch (RgnDesc, ACPI_READ_ADR_SPACE,
                        Address, ObjDesc->CommonField.AccessBitWidth, Value);
        if (Status == AE_NOT_IMPLEMENTED)
        {
            ACPI_DEBUG_PRINT ((ACPI_DB_ERROR, "Region %s(%X) not implemented\n",
                AcpiUtGetRegionName (RgnDesc->Region.SpaceId),
                RgnDesc->Region.SpaceId));
        }

        else if (Status == AE_NOT_EXIST)
        {
            ACPI_DEBUG_PRINT ((ACPI_DB_ERROR, "Region %s(%X) has no handler\n",
                AcpiUtGetRegionName (RgnDesc->Region.SpaceId),
                RgnDesc->Region.SpaceId));
        }
        break;


    default:

        ACPI_DEBUG_PRINT ((ACPI_DB_ERROR, "%p, wrong source type - %s\n",
            ObjDesc, AcpiUtGetTypeName (ObjDesc->Common.Type)));
        Status = AE_AML_INTERNAL;
        break;
    }


    ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD, "Returned value=%08lX \n", *Value));

    return_ACPI_STATUS (Status);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiExGetBufferDatum
 *
 * PARAMETERS:  MergedDatum         - Value to store
 *              Buffer              - Receiving buffer
 *              ByteGranularity     - 1/2/4 Granularity of the field 
 *                                    (aka Datum Size)
 *              Offset              - Datum offset into the buffer
 *              
 * RETURN:      none
 *
 * DESCRIPTION: Store the merged datum to the buffer according to the
 *              byte granularity
 *
 ******************************************************************************/

static void
AcpiExGetBufferDatum(
    UINT32                  *Datum,
    void                    *Buffer,
    UINT32                  ByteGranularity,
    UINT32                  Offset)
{

    switch (ByteGranularity)
    {
    case ACPI_FIELD_BYTE_GRANULARITY:
        *Datum = ((UINT8 *) Buffer) [Offset];
        break;

    case ACPI_FIELD_WORD_GRANULARITY:
        MOVE_UNALIGNED16_TO_32 (Datum, &(((UINT16 *) Buffer) [Offset]));
        break;

    case ACPI_FIELD_DWORD_GRANULARITY:
        MOVE_UNALIGNED32_TO_32 (Datum, &(((UINT32 *) Buffer) [Offset]));
        break;
    }
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiExSetBufferDatum 
 *
 * PARAMETERS:  MergedDatum         - Value to store
 *              Buffer              - Receiving buffer
 *              ByteGranularity     - 1/2/4 Granularity of the field 
 *                                    (aka Datum Size)
 *              Offset              - Datum offset into the buffer
 *              
 * RETURN:      none
 *
 * DESCRIPTION: Store the merged datum to the buffer according to the
 *              byte granularity
 *
 ******************************************************************************/

static void
AcpiExSetBufferDatum (
    UINT32                  MergedDatum,
    void                    *Buffer,
    UINT32                  ByteGranularity,
    UINT32                  Offset)
{

    switch (ByteGranularity)
    {
    case ACPI_FIELD_BYTE_GRANULARITY:
        ((UINT8 *) Buffer) [Offset] = (UINT8) MergedDatum;
        break;

    case ACPI_FIELD_WORD_GRANULARITY:
        MOVE_UNALIGNED16_TO_16 (&(((UINT16 *) Buffer)[Offset]), &MergedDatum);
        break;

    case ACPI_FIELD_DWORD_GRANULARITY:
        MOVE_UNALIGNED32_TO_32 (&(((UINT32 *) Buffer)[Offset]), &MergedDatum);
        break;
    }
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiExExtractFromField
 *
 * PARAMETERS:  *ObjDesc            - Field to be read
 *              *Value              - Where to store value
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Retrieve the value of the given field
 *
 ******************************************************************************/

ACPI_STATUS
AcpiExExtractFromField (
    ACPI_OPERAND_OBJECT     *ObjDesc,
    void                    *Buffer,
    UINT32                  BufferLength)
{
    ACPI_STATUS             Status;
    UINT32                  FieldDatumByteOffset;
    UINT32                  DatumOffset;
    UINT32                  PreviousRawDatum;
    UINT32                  ThisRawDatum = 0;
    UINT32                  MergedDatum = 0;
    UINT32                  ByteFieldLength;
    UINT32                  DatumCount;


    FUNCTION_TRACE ("ExExtractFromField");


    /*
     * The field must fit within the caller's buffer
     */
    ByteFieldLength = ROUND_BITS_UP_TO_BYTES (ObjDesc->CommonField.BitLength);
    if (ByteFieldLength > BufferLength)
    {
        ACPI_DEBUG_PRINT ((ACPI_DB_INFO, "Field size %X (bytes) too large for buffer (%X)\n",
            ByteFieldLength, BufferLength));

        return_ACPI_STATUS (AE_BUFFER_OVERFLOW);
    }

    /* Convert field byte count to datum count, round up if necessary */

    DatumCount = ROUND_UP_TO (ByteFieldLength, ObjDesc->CommonField.AccessByteWidth);

    ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
        "ByteLen=%x, DatumLen=%x, BitGran=%x, ByteGran=%x\n",
        ByteFieldLength, DatumCount, ObjDesc->CommonField.AccessBitWidth, 
        ObjDesc->CommonField.AccessByteWidth));


    /*
     * Clear the caller's buffer (the whole buffer length as given)
     * This is very important, especially in the cases where a byte is read,
     * but the buffer is really a UINT32 (4 bytes).
     */
    MEMSET (Buffer, 0, BufferLength);

    /* Read the first raw datum to prime the loop */

    FieldDatumByteOffset = 0;
    DatumOffset= 0;

    Status = AcpiExReadFieldDatum (ObjDesc, FieldDatumByteOffset, &PreviousRawDatum);
    if (ACPI_FAILURE (Status))
    {
        return_ACPI_STATUS (Status);
    }


    /* We might actually be done if the request fits in one datum */

    if ((DatumCount == 1) &&
        (ObjDesc->CommonField.AccessFlags & AFIELD_SINGLE_DATUM))
    {
        /* 1) Shift the valid data bits down to start at bit 0 */

        MergedDatum = (PreviousRawDatum >> ObjDesc->CommonField.StartFieldBitOffset);

        /* 2) Mask off any upper unused bits (bits not part of the field) */

        if (ObjDesc->CommonField.EndBufferValidBits)
        {
            MergedDatum &= MASK_BITS_ABOVE (ObjDesc->CommonField.EndBufferValidBits);
        }

        /* Store the datum to the caller buffer */

        AcpiExSetBufferDatum (MergedDatum, Buffer, ObjDesc->CommonField.AccessByteWidth, 
                DatumOffset);

        return_ACPI_STATUS (AE_OK);
    }


    /* We need to get more raw data to complete one or more field data */

    while (DatumOffset < DatumCount)
    {
        FieldDatumByteOffset += ObjDesc->CommonField.AccessByteWidth;

        /*
         * If the field is aligned on a byte boundary, we don't want
         * to perform a final read, since this would potentially read
         * past the end of the region.
         *
         * TBD: [Investigate] It may make more sense to just split the aligned
         * and non-aligned cases since the aligned case is so very simple,
         */
        if ((ObjDesc->CommonField.StartFieldBitOffset != 0)       ||
            ((ObjDesc->CommonField.StartFieldBitOffset == 0)      &&
            (DatumOffset < (DatumCount -1))))
        {
            /*
             * Get the next raw datum, it contains some or all bits
             * of the current field datum
             */
            Status = AcpiExReadFieldDatum (ObjDesc, FieldDatumByteOffset, &ThisRawDatum);
            if (ACPI_FAILURE (Status))
            {
                return_ACPI_STATUS (Status);
            }
        }

        /*
         * Create the (possibly) merged datum to be stored to the caller buffer
         */
        if (ObjDesc->CommonField.StartFieldBitOffset == 0)
        {
            /* Field is not skewed and we can just copy the datum */

            MergedDatum = PreviousRawDatum;
        }

        else
        {
            /*
             * Put together the appropriate bits of the two raw data to make a 
             * single complete field datum
             *
             * 1) Normalize the first datum down to bit 0 
             */
            MergedDatum = (PreviousRawDatum >> ObjDesc->CommonField.StartFieldBitOffset);

            /* 2) Insert the second datum "above" the first datum */

            MergedDatum |= (ThisRawDatum << ObjDesc->CommonField.DatumValidBits);
        
            if ((DatumOffset >= (DatumCount -1)))
            {
                /*
                 * This is the last iteration of the loop.  We need to clear
                 * any unused bits (bits that are not part of this field) that 
                 * came from the last raw datum before we store the final 
                 * merged datum into the caller buffer.
                 */
                if (ObjDesc->CommonField.EndBufferValidBits)
                {
                    MergedDatum &= 
                        MASK_BITS_ABOVE (ObjDesc->CommonField.EndBufferValidBits);
                }
            }
        }


        /*
         * Store the merged field datum in the caller's buffer, according to
         * the granularity of the field (size of each datum).
         */
        AcpiExSetBufferDatum (MergedDatum, Buffer, ObjDesc->CommonField.AccessByteWidth, 
                DatumOffset);

        /*
         * Save the raw datum that was just acquired since it may contain bits 
         * of the *next* field datum.  Update offsets
         */
        PreviousRawDatum = ThisRawDatum;
        DatumOffset++;
    }


    return_ACPI_STATUS (AE_OK);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiExWriteFieldDatum
 *
 * PARAMETERS:  *ObjDesc            - Field to be set
 *              Value               - Value to store
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Store the value into the given field
 *
 ******************************************************************************/

static ACPI_STATUS
AcpiExWriteFieldDatum (
    ACPI_OPERAND_OBJECT     *ObjDesc,
    UINT32                  FieldDatumByteOffset,
    UINT32                  Value)
{
    ACPI_STATUS             Status = AE_OK;
    ACPI_OPERAND_OBJECT     *RgnDesc = NULL;
    ACPI_PHYSICAL_ADDRESS   Address;


    FUNCTION_TRACE_U32 ("ExWriteFieldDatum", FieldDatumByteOffset);



    /*
     * BufferFields - Read from a Buffer
     * Other Fields - Read from a Operation Region.
     */
    switch (ObjDesc->Common.Type)
    {
    case ACPI_TYPE_BUFFER_FIELD:

        /*
         * For BufferFields, we only need to copy the data to the
         * target buffer.  Length is the field width in bytes.
         */
        MEMCPY ((ObjDesc->BufferField.BufferObj)->Buffer.Pointer
                + ObjDesc->BufferField.BaseByteOffset + FieldDatumByteOffset,
                &Value, ObjDesc->CommonField.AccessByteWidth);
        Status = AE_OK;
        break;


    case INTERNAL_TYPE_REGION_FIELD:
    case INTERNAL_TYPE_BANK_FIELD:

        /*
         * For other fields, we need to go through an Operation Region
         * (Only types that will get here are RegionFields and BankFields)
         */
        Status = AcpiExSetupField (ObjDesc, FieldDatumByteOffset);
        if (ACPI_FAILURE (Status))
        {
            return_ACPI_STATUS (Status);
        }

        /*
         * The physical address of this field datum is:
         *
         * 1) The base of the region, plus
         * 2) The base offset of the field, plus
         * 3) The current offset into the field
         */
        RgnDesc = ObjDesc->CommonField.RegionObj;
        Address = RgnDesc->Region.Address + 
                    ObjDesc->CommonField.BaseByteOffset +
                    FieldDatumByteOffset;

        ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD, 
            "Store %X in Region %s(%X) at %8.8lX%8.8lX width %X\n",
            Value, AcpiUtGetRegionName (RgnDesc->Region.SpaceId),
            RgnDesc->Region.SpaceId, HIDWORD(Address), LODWORD(Address),
            ObjDesc->CommonField.AccessBitWidth));

        /* Invoke the appropriate AddressSpace/OpRegion handler */

        Status = AcpiEvAddressSpaceDispatch (RgnDesc, ACPI_WRITE_ADR_SPACE,
                        Address, ObjDesc->CommonField.AccessBitWidth, &Value);

        if (Status == AE_NOT_IMPLEMENTED)
        {
            ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,  
                "**** Region type %s(%X) not implemented\n",
                AcpiUtGetRegionName (RgnDesc->Region.SpaceId),
                RgnDesc->Region.SpaceId));
        }

        else if (Status == AE_NOT_EXIST)
        {
            ACPI_DEBUG_PRINT ((ACPI_DB_ERROR, 
                "**** Region type %s(%X) does not have a handler\n",
                AcpiUtGetRegionName (RgnDesc->Region.SpaceId),
                RgnDesc->Region.SpaceId));
        }

        break;


    default:

        ACPI_DEBUG_PRINT ((ACPI_DB_ERROR, "%p, wrong source type - %s\n",
            ObjDesc, AcpiUtGetTypeName (ObjDesc->Common.Type)));
        Status = AE_AML_INTERNAL;
        break;
    }


    ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD, "Value written=%08lX \n", Value));
    return_ACPI_STATUS (Status);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiExWriteFieldDatumWithUpdateRule
 *
 * PARAMETERS:  *ObjDesc            - Field to be set
 *              Value               - Value to store
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Apply the field update rule to a field write
 *
 ******************************************************************************/

static ACPI_STATUS
AcpiExWriteFieldDatumWithUpdateRule (
    ACPI_OPERAND_OBJECT     *ObjDesc,
    UINT32                  Mask,
    UINT32                  FieldValue,
    UINT32                  FieldDatumByteOffset)
{
    ACPI_STATUS             Status = AE_OK;
    UINT32                  MergedValue;
    UINT32                  CurrentValue;


    FUNCTION_TRACE ("ExWriteFieldDatumWithUpdateRule");


    /* Start with the new bits  */

    MergedValue = FieldValue;


    /* If the mask is all ones, we don't need to worry about the update rule */

    if (Mask != ACPI_UINT32_MAX)
    {
        /* Decode the update rule */

        switch (ObjDesc->CommonField.UpdateRule)
        {

        case UPDATE_PRESERVE:

            /* 
             * Check if update rule needs to be applied (not if mask is all 
             * ones)  The left shift drops the bits we want to ignore. 
             */
            if ((~Mask << (sizeof (Mask) * 8 - 
                            ObjDesc->CommonField.AccessBitWidth)) != 0)
            {
                /*
                 * Read the current contents of the byte/word/dword containing
                 * the field, and merge with the new field value.
                 */
                Status = AcpiExReadFieldDatum (ObjDesc, FieldDatumByteOffset, 
                                &CurrentValue);
                MergedValue |= (CurrentValue & ~Mask);
            }
            break;


        case UPDATE_WRITE_AS_ONES:

            /* Set positions outside the field to all ones */

            MergedValue |= ~Mask;
            break;


        case UPDATE_WRITE_AS_ZEROS:

            /* Set positions outside the field to all zeros */

            MergedValue &= Mask;
            break;


        default:
            ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
                "WriteWithUpdateRule: Unknown UpdateRule setting: %x\n",
                ObjDesc->CommonField.UpdateRule));
            return_ACPI_STATUS (AE_AML_OPERAND_VALUE);
            break;
        }
    }


    /* Write the merged value */

    Status = AcpiExWriteFieldDatum (ObjDesc, FieldDatumByteOffset, 
                    MergedValue);

    ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD, "Mask %X DatumOffset %X Value %X, MergedValue %X\n",
        Mask, FieldDatumByteOffset, FieldValue, MergedValue));

    return_ACPI_STATUS (Status);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiExInsertIntoField
 *
 * PARAMETERS:  *ObjDesc            - Field to be set
 *              Buffer              - Value to store
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Store the value into the given field
 *
 ******************************************************************************/

ACPI_STATUS
AcpiExInsertIntoField (
    ACPI_OPERAND_OBJECT     *ObjDesc,
    void                    *Buffer,
    UINT32                  BufferLength)
{
    ACPI_STATUS             Status;
    UINT32                  FieldDatumByteOffset;
    UINT32                  DatumOffset;
    UINT32                  Mask;
    UINT32                  MergedDatum;
    UINT32                  PreviousRawDatum;
    UINT32                  ThisRawDatum;
    UINT32                  ByteFieldLength;
    UINT32                  DatumCount;


    FUNCTION_TRACE ("ExInsertIntoField");


    /*
     * Incoming buffer must be at least as long as the field, we do not 
     * allow "partial" field writes.  We do not care if the buffer is
     * larger than the field, this typically happens when an integer is
     * written to a field that is actually smaller than an integer.
     */
    ByteFieldLength = ROUND_BITS_UP_TO_BYTES (ObjDesc->CommonField.BitLength);
    if (BufferLength < ByteFieldLength)
    {
        ACPI_DEBUG_PRINT ((ACPI_DB_INFO, "Buffer length %X too small for field %X\n",
            BufferLength, ByteFieldLength));

        /* TBD: Need a better error code */

        return_ACPI_STATUS (AE_BUFFER_OVERFLOW);
    }

    /* Convert byte count to datum count, round up if necessary */

    DatumCount = ROUND_UP_TO (ByteFieldLength, ObjDesc->CommonField.AccessByteWidth);

    ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
        "ByteLen=%x, DatumLen=%x, BitGran=%x, ByteGran=%x\n",
        ByteFieldLength, DatumCount, ObjDesc->CommonField.AccessBitWidth, 
        ObjDesc->CommonField.AccessByteWidth));


    /*
     * Break the request into up to three parts (similar to an I/O request):
     * 1) non-aligned part at start
     * 2) aligned part in middle
     * 3) non-aligned part at the end
     */
    FieldDatumByteOffset = 0;
    DatumOffset= 0;

    /* Get a single datum from the caller's buffer */

    AcpiExGetBufferDatum (&PreviousRawDatum, Buffer, 
            ObjDesc->CommonField.AccessByteWidth, DatumOffset);

    /*
     * Part1:
     * Write a partial field datum if field does not begin on a datum boundary
     * Note: The code in this section also handles the aligned case
     *
     * Construct Mask with 1 bits where the field is, 0 bits elsewhere
     * (Only the bottom 5 bits of BitLength are valid for a shift operation)
     *
     * Mask off bits that are "below" the field (if any)
     */
    Mask = MASK_BITS_BELOW (ObjDesc->CommonField.StartFieldBitOffset);

    /* If the field fits in one datum, may need to mask upper bits */

    if ((ObjDesc->CommonField.AccessFlags & AFIELD_SINGLE_DATUM) &&
         ObjDesc->CommonField.EndFieldValidBits)
    {
        /* There are bits above the field, mask them off also */

        Mask &= MASK_BITS_ABOVE (ObjDesc->CommonField.EndFieldValidBits);
    }

    /* Shift and mask the value into the field position */

    MergedDatum = (PreviousRawDatum << ObjDesc->CommonField.StartFieldBitOffset);
    MergedDatum &= Mask;

    /* Apply the update rule (if necessary) and write the datum to the field */

    Status = AcpiExWriteFieldDatumWithUpdateRule (ObjDesc, Mask, MergedDatum,
                        FieldDatumByteOffset);
    if (ACPI_FAILURE (Status))
    {
        return_ACPI_STATUS (Status);
    }

    /* If the entire field fits within one datum, we are done. */

    if ((DatumCount == 1) &&
       (ObjDesc->CommonField.AccessFlags & AFIELD_SINGLE_DATUM))
    {
        return_ACPI_STATUS (AE_OK);
    }

    /*
     * Part2:
     * Write the aligned data.
     *
     * We don't need to worry about the update rule for these data, because
     * all of the bits in each datum are part of the field.
     *
     * The last datum must be special cased because it might contain bits 
     * that are not part of the field -- therefore the "update rule" must be 
     * applied in Part3 below.
     */
    while (DatumOffset < DatumCount)
    {
        DatumOffset++;
        FieldDatumByteOffset += ObjDesc->CommonField.AccessByteWidth;

        /* 
         * Get the next raw buffer datum.  It may contain bits of the previous 
         * field datum
         */
        AcpiExGetBufferDatum (&ThisRawDatum, Buffer, 
                ObjDesc->CommonField.AccessByteWidth, DatumOffset);

        /* Create the field datum based on the field alignment */

        if (ObjDesc->CommonField.StartFieldBitOffset != 0)
        {
            /*
             * Put together appropriate bits of the two raw buffer data to make 
             * a single complete field datum
             */
            MergedDatum = 
                (PreviousRawDatum >> ObjDesc->CommonField.DatumValidBits) |
                (ThisRawDatum << ObjDesc->CommonField.StartFieldBitOffset);
        }

        else
        {
            /* Field began aligned on datum boundary */

            MergedDatum = ThisRawDatum;
        }


        /*
         * Special handling for the last datum if the field does NOT end on
         * a datum boundary.  Update Rule must be applied to the bits outside
         * the field.
         */
        if ((DatumOffset == DatumCount)             &&
            ObjDesc->CommonField.EndFieldValidBits)
        {
            /* 
             * Part3: 
             * This is the last datum and the field does not end on a datum boundary.
             * Build the partial datum and write with the update rule.
             */

            /* Mask off the unused bits above (after) the end-of-field */

            Mask = MASK_BITS_ABOVE (ObjDesc->CommonField.EndFieldValidBits);
            MergedDatum &= Mask;

            /* Write the last datum with the update rule */

            Status = AcpiExWriteFieldDatumWithUpdateRule (ObjDesc, Mask, 
                            MergedDatum, FieldDatumByteOffset);
            if (ACPI_FAILURE (Status))
            {
                return_ACPI_STATUS (Status);
            }
        }

        else
        {
            /* Normal case -- write the completed datum */

            Status = AcpiExWriteFieldDatum (ObjDesc, 
                            FieldDatumByteOffset, MergedDatum);
            if (ACPI_FAILURE (Status))
            {
                return_ACPI_STATUS (Status);
            }
        }

        /*
         * Save the most recent datum since it may contain bits of the *next* 
         * field datum.  Update current byte offset.
         */
        PreviousRawDatum = ThisRawDatum;
    }


    return_ACPI_STATUS (Status);
}