exfield.c

acpi tools for linux include acpiexec and acpixtract

     *
     * Note: Field.length is in bits.
     */
    Length = (ACPI_SIZE) ACPI_ROUND_BITS_UP_TO_BYTES (ObjDesc->Field.BitLength);
    if (Length > AcpiGbl_IntegerByteWidth)
    {
        /* Field is too large for an Integer, create a Buffer instead */

        BufferDesc = AcpiUtCreateBufferObject (Length);
        if (!BufferDesc)
        {
            return_ACPI_STATUS (AE_NO_MEMORY);
        }
        Buffer = BufferDesc->Buffer.Pointer;
    }
    else
    {
        /* Field will fit within an Integer (normal case) */

        BufferDesc = AcpiUtCreateInternalObject (ACPI_TYPE_INTEGER);
        if (!BufferDesc)
        {
            return_ACPI_STATUS (AE_NO_MEMORY);
        }

        Length = AcpiGbl_IntegerByteWidth;
        BufferDesc->Integer.Value = 0;
        Buffer = &BufferDesc->Integer.Value;
    }

    ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
        "FieldRead [TO]:   Obj %p, Type %X, Buf %p, ByteLen %X\n",
        ObjDesc, ACPI_GET_OBJECT_TYPE (ObjDesc), Buffer, (UINT32) Length));
    ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
        "FieldRead [FROM]: BitLen %X, BitOff %X, ByteOff %X\n",
        ObjDesc->CommonField.BitLength,
        ObjDesc->CommonField.StartFieldBitOffset,
        ObjDesc->CommonField.BaseByteOffset));

    /* Lock entire transaction if requested */

    AcpiExAcquireGlobalLock (ObjDesc->CommonField.FieldFlags);

    /* Read from the field */

    Status = AcpiExExtractFromField (ObjDesc, Buffer, (UINT32) Length);
    AcpiExReleaseGlobalLock (ObjDesc->CommonField.FieldFlags);


Exit:
    if (ACPI_FAILURE (Status))
    {
        AcpiUtRemoveReference (BufferDesc);
    }
    else
    {
        *RetBufferDesc = BufferDesc;
    }

    return_ACPI_STATUS (Status);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiExWriteDataToField
 *
 * PARAMETERS:  SourceDesc          - Contains data to write
 *              ObjDesc             - The named field
 *              ResultDesc          - Where the return value is returned, if any
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Write to a named field
 *
 ******************************************************************************/

ACPI_STATUS
AcpiExWriteDataToField (
    ACPI_OPERAND_OBJECT     *SourceDesc,
    ACPI_OPERAND_OBJECT     *ObjDesc,
    ACPI_OPERAND_OBJECT     **ResultDesc)
{
    ACPI_STATUS             Status;
    UINT32                  Length;
    void                    *Buffer;
    ACPI_OPERAND_OBJECT     *BufferDesc;


    ACPI_FUNCTION_TRACE_PTR (ExWriteDataToField, ObjDesc);


    /* Parameter validation */

    if (!SourceDesc || !ObjDesc)
    {
        return_ACPI_STATUS (AE_AML_NO_OPERAND);
    }

    if (ACPI_GET_OBJECT_TYPE (ObjDesc) == ACPI_TYPE_BUFFER_FIELD)
    {
        /*
         * If the BufferField arguments have not been previously evaluated,
         * evaluate them now and save the results.
         */
        if (!(ObjDesc->Common.Flags & AOPOBJ_DATA_VALID))
        {
            Status = AcpiDsGetBufferFieldArguments (ObjDesc);
            if (ACPI_FAILURE (Status))
            {
                return_ACPI_STATUS (Status);
            }
        }
    }
    else if ((ACPI_GET_OBJECT_TYPE (ObjDesc) == ACPI_TYPE_LOCAL_REGION_FIELD) &&
             (ObjDesc->Field.RegionObj->Region.SpaceId == ACPI_ADR_SPACE_SMBUS))
    {
        /*
         * This is an SMBus write.  We will bypass the entire field mechanism
         * and handoff the buffer directly to the handler.
         *
         * Source must be a buffer of sufficient size (ACPI_SMBUS_BUFFER_SIZE).
         */
        if (ACPI_GET_OBJECT_TYPE (SourceDesc) != ACPI_TYPE_BUFFER)
        {
            ACPI_ERROR ((AE_INFO, "SMBus write requires Buffer, found type %s",
                AcpiUtGetObjectTypeName (SourceDesc)));

            return_ACPI_STATUS (AE_AML_OPERAND_TYPE);
        }

        if (SourceDesc->Buffer.Length < ACPI_SMBUS_BUFFER_SIZE)
        {
            ACPI_ERROR ((AE_INFO,
                "SMBus write requires Buffer of length %X, found length %X",
                ACPI_SMBUS_BUFFER_SIZE, SourceDesc->Buffer.Length));

            return_ACPI_STATUS (AE_AML_BUFFER_LIMIT);
        }

        BufferDesc = AcpiUtCreateBufferObject (ACPI_SMBUS_BUFFER_SIZE);
        if (!BufferDesc)
        {
            return_ACPI_STATUS (AE_NO_MEMORY);
        }

        Buffer = BufferDesc->Buffer.Pointer;
        ACPI_MEMCPY (Buffer, SourceDesc->Buffer.Pointer,
            ACPI_SMBUS_BUFFER_SIZE);

        /* Lock entire transaction if requested */

        AcpiExAcquireGlobalLock (ObjDesc->CommonField.FieldFlags);

        /*
         * Perform the write (returns status and perhaps data in the
         * same buffer)
         * Note: SMBus protocol type is passed in upper 16-bits of Function.
         */
        Status = AcpiExAccessRegion (ObjDesc, 0,
                        (ACPI_INTEGER *) Buffer,
                        ACPI_WRITE | (ObjDesc->Field.Attribute << 16));
        AcpiExReleaseGlobalLock (ObjDesc->CommonField.FieldFlags);

        *ResultDesc = BufferDesc;
        return_ACPI_STATUS (Status);
    }

    /* Get a pointer to the data to be written */

    switch (ACPI_GET_OBJECT_TYPE (SourceDesc))
    {
    case ACPI_TYPE_INTEGER:
        Buffer = &SourceDesc->Integer.Value;
        Length = sizeof (SourceDesc->Integer.Value);
        break;

    case ACPI_TYPE_BUFFER:
        Buffer = SourceDesc->Buffer.Pointer;
        Length = SourceDesc->Buffer.Length;
        break;

    case ACPI_TYPE_STRING:
        Buffer = SourceDesc->String.Pointer;
        Length = SourceDesc->String.Length;
        break;

    default:
        return_ACPI_STATUS (AE_AML_OPERAND_TYPE);
    }

    ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
        "FieldWrite [FROM]: Obj %p (%s:%X), Buf %p, ByteLen %X\n",
        SourceDesc, AcpiUtGetTypeName (ACPI_GET_OBJECT_TYPE (SourceDesc)),
        ACPI_GET_OBJECT_TYPE (SourceDesc), Buffer, Length));

    ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
        "FieldWrite [TO]:   Obj %p (%s:%X), BitLen %X, BitOff %X, ByteOff %X\n",
        ObjDesc, AcpiUtGetTypeName (ACPI_GET_OBJECT_TYPE (ObjDesc)),
        ACPI_GET_OBJECT_TYPE (ObjDesc),
        ObjDesc->CommonField.BitLength,
        ObjDesc->CommonField.StartFieldBitOffset,
        ObjDesc->CommonField.BaseByteOffset));

    /* Lock entire transaction if requested */

    AcpiExAcquireGlobalLock (ObjDesc->CommonField.FieldFlags);

    /* Write to the field */

    Status = AcpiExInsertIntoField (ObjDesc, Buffer, Length);
    AcpiExReleaseGlobalLock (ObjDesc->CommonField.FieldFlags);

    return_ACPI_STATUS (Status);
}