exfldio.c

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/******************************************************************************
 *
 * Module Name: exfldio - Aml Field I/O
 *
 *****************************************************************************/

/*
 * Copyright (C) 2000 - 2012, 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/acpi.h>
#include "accommon.h"
#include "acinterp.h"
#include "amlcode.h"
#include "acevents.h"
#include "acdispat.h"

#define _COMPONENT          ACPI_EXECUTER
ACPI_MODULE_NAME("exfldio")

/* Local prototypes */
static acpi_status
acpi_ex_field_datum_io(union acpi_operand_object *obj_desc,
               u32 field_datum_byte_offset,
               u64 *value, u32 read_write);

static u8
acpi_ex_register_overflow(union acpi_operand_object *obj_desc, u64 value);

static acpi_status
acpi_ex_setup_region(union acpi_operand_object *obj_desc,
             u32 field_datum_byte_offset);

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_setup_region
 *
 * PARAMETERS:  obj_desc                - Field to be read or written
 *              field_datum_byte_offset - Byte offset of this datum within the
 *                                        parent field
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Common processing for acpi_ex_extract_from_field and
 *              acpi_ex_insert_into_field. Initialize the Region if necessary and
 *              validate the request.
 *
 ******************************************************************************/

static acpi_status
acpi_ex_setup_region(union acpi_operand_object *obj_desc,
             u32 field_datum_byte_offset)
{
    acpi_status status = AE_OK;
    union acpi_operand_object *rgn_desc;
    u8 space_id;

    ACPI_FUNCTION_TRACE_U32(ex_setup_region, field_datum_byte_offset);

    rgn_desc = obj_desc->common_field.region_obj;

    /* We must have a valid region */

    if (rgn_desc->common.type != ACPI_TYPE_REGION) {
        ACPI_ERROR((AE_INFO, "Needed Region, found type 0x%X (%s)",
                rgn_desc->common.type,
                acpi_ut_get_object_type_name(rgn_desc)));

        return_ACPI_STATUS(AE_AML_OPERAND_TYPE);
    }

    space_id = rgn_desc->region.space_id;

    /* Validate the Space ID */

    if (!acpi_is_valid_space_id(space_id)) {
        ACPI_ERROR((AE_INFO,
                "Invalid/unknown Address Space ID: 0x%2.2X",
                space_id));
        return_ACPI_STATUS(AE_AML_INVALID_SPACE_ID);
    }

    /*
     * If the Region Address and Length have not been previously evaluated,
     * evaluate them now and save the results.
     */
    if (!(rgn_desc->common.flags & AOPOBJ_DATA_VALID)) {
        status = acpi_ds_get_region_arguments(rgn_desc);
        if (ACPI_FAILURE(status)) {
            return_ACPI_STATUS(status);
        }
    }

    /* Exit if Address/Length have been disallowed by the host OS */

    if (rgn_desc->common.flags & AOPOBJ_INVALID) {
        return_ACPI_STATUS(AE_AML_ILLEGAL_ADDRESS);
    }

    /*
     * Exit now for SMBus, GSBus or IPMI address space, it has a non-linear
     * address space and the request cannot be directly validated
     */
    if (space_id == ACPI_ADR_SPACE_SMBUS ||
        space_id == ACPI_ADR_SPACE_GSBUS ||
        space_id == ACPI_ADR_SPACE_IPMI) {

        /* SMBus or IPMI has a non-linear address space */

        return_ACPI_STATUS(AE_OK);
    }
#ifdef ACPI_UNDER_DEVELOPMENT
    /*
     * If the Field access is any_acc, we can now compute the optimal
     * access (because we know know the length of the parent region)
     */
    if (!(obj_desc->common.flags & AOPOBJ_DATA_VALID)) {
        if (ACPI_FAILURE(status)) {
            return_ACPI_STATUS(status);
        }
    }
#endif

    /*
     * 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 (rgn_desc->region.length <
        (obj_desc->common_field.base_byte_offset + field_datum_byte_offset +
         obj_desc->common_field.access_byte_width)) {
        if (acpi_gbl_enable_interpreter_slack) {
            /*
             * Slack mode only:  We will go ahead and allow access to this
             * field if it is within the region length rounded up to the next
             * access width boundary. acpi_size cast for 64-bit compile.
             */
            if (ACPI_ROUND_UP(rgn_desc->region.length,
                      obj_desc->common_field.
                      access_byte_width) >=
                ((acpi_size) obj_desc->common_field.
                 base_byte_offset +
                 obj_desc->common_field.access_byte_width +
                 field_datum_byte_offset)) {
                return_ACPI_STATUS(AE_OK);
            }
        }

        if (rgn_desc->region.length <
            obj_desc->common_field.access_byte_width) {
            /*
             * This is the case where the access_type (acc_word, etc.) is wider
             * than the region itself.  For example, a region of length one
             * byte, and a field with Dword access specified.
             */
            ACPI_ERROR((AE_INFO,
                    "Field [%4.4s] access width (%u bytes) too large for region [%4.4s] (length %u)",
                    acpi_ut_get_node_name(obj_desc->
                              common_field.node),
                    obj_desc->common_field.access_byte_width,
                    acpi_ut_get_node_name(rgn_desc->region.
                              node),
                    rgn_desc->region.length));
        }

        /*
         * Offset rounded up to next multiple of field width
         * exceeds region length, indicate an error
         */
        ACPI_ERROR((AE_INFO,
                "Field [%4.4s] Base+Offset+Width %u+%u+%u is beyond end of region [%4.4s] (length %u)",
                acpi_ut_get_node_name(obj_desc->common_field.node),
                obj_desc->common_field.base_byte_offset,
                field_datum_byte_offset,
                obj_desc->common_field.access_byte_width,
                acpi_ut_get_node_name(rgn_desc->region.node),
                rgn_desc->region.length));

        return_ACPI_STATUS(AE_AML_REGION_LIMIT);
    }

    return_ACPI_STATUS(AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_access_region
 *
 * PARAMETERS:  obj_desc                - Field to be read
 *              field_datum_byte_offset - Byte offset of this datum within the
 *                                        parent field
 *              value                   - Where to store value (must at least
 *                                        64 bits)
 *              function                - Read or Write flag plus other region-
 *                                        dependent flags
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Read or Write a single field datum to an Operation Region.
 *
 ******************************************************************************/

acpi_status
acpi_ex_access_region(union acpi_operand_object *obj_desc,
              u32 field_datum_byte_offset, u64 *value, u32 function)
{
    acpi_status status;
    union acpi_operand_object *rgn_desc;
    u32 region_offset;

    ACPI_FUNCTION_TRACE(ex_access_region);

    /*
     * Ensure that the region operands are fully evaluated and verify
     * the validity of the request
     */
    status = acpi_ex_setup_region(obj_desc, field_datum_byte_offset);
    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
     */
    rgn_desc = obj_desc->common_field.region_obj;
    region_offset =
        obj_desc->common_field.base_byte_offset + field_datum_byte_offset;

    if ((function & ACPI_IO_MASK) == ACPI_READ) {
        ACPI_DEBUG_PRINT((ACPI_DB_BFIELD, "[READ]"));
    } else {
        ACPI_DEBUG_PRINT((ACPI_DB_BFIELD, "[WRITE]"));
    }

    ACPI_DEBUG_PRINT_RAW((ACPI_DB_BFIELD,
                  " Region [%s:%X], Width %X, ByteBase %X, Offset %X at %p\n",
                  acpi_ut_get_region_name(rgn_desc->region.
                              space_id),
                  rgn_desc->region.space_id,
                  obj_desc->common_field.access_byte_width,
                  obj_desc->common_field.base_byte_offset,
                  field_datum_byte_offset, ACPI_CAST_PTR(void,
                                     (rgn_desc->
                                      region.
                                      address +
                                      region_offset))));

    /* Invoke the appropriate address_space/op_region handler */

    status = acpi_ev_address_space_dispatch(rgn_desc, obj_desc,
                        function, region_offset,
                        ACPI_MUL_8(obj_desc->
                               common_field.
                               access_byte_width),
                        value);

    if (ACPI_FAILURE(status)) {
        if (status == AE_NOT_IMPLEMENTED) {
            ACPI_ERROR((AE_INFO,
                    "Region %s (ID=%u) not implemented",
                    acpi_ut_get_region_name(rgn_desc->region.
                                space_id),
                    rgn_desc->region.space_id));
        } else if (status == AE_NOT_EXIST) {
            ACPI_ERROR((AE_INFO,
                    "Region %s (ID=%u) has no handler",
                    acpi_ut_get_region_name(rgn_desc->region.
                                space_id),
                    rgn_desc->region.space_id));
        }
    }

    return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_register_overflow
 *
 * PARAMETERS:  obj_desc                - Register(Field) to be written
 *              value                   - Value to be stored
 *
 * RETURN:      TRUE if value overflows the field, FALSE otherwise
 *
 * DESCRIPTION: Check if a value is out of range of the field being written.
 *              Used to check if the values written to Index and Bank registers
 *              are out of range.  Normally, the value is simply truncated
 *              to fit the field, but this case is most likely a serious
 *              coding error in the ASL.
 *
 ******************************************************************************/

static u8
acpi_ex_register_overflow(union acpi_operand_object *obj_desc, u64 value)
{
    ACPI_FUNCTION_NAME(ex_register_overflow);

    if (obj_desc->common_field.bit_length >= ACPI_INTEGER_BIT_SIZE) {
        /*
         * The field is large enough to hold the maximum integer, so we can
         * never overflow it.
         */
        return (FALSE);
    }

    if (value >= ((u64) 1 << obj_desc->common_field.bit_length)) {
        /*
         * The Value is larger than the maximum value that can fit into
         * the register.
         */
        ACPI_ERROR((AE_INFO,
                "Index value 0x%8.8X%8.8X overflows field width 0x%X",
                ACPI_FORMAT_UINT64(value),
                obj_desc->common_field.bit_length));

        return (TRUE);
    }

    /* The Value will fit into the field with no truncation */

    return (FALSE);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_field_datum_io
 *
 * PARAMETERS:  obj_desc                - Field to be read
 *              field_datum_byte_offset - Byte offset of this datum within the
 *                                        parent field
 *              value                   - Where to store value (must be 64 bits)
 *              read_write              - Read or Write flag
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Read or Write a single datum of a field.  The field_type is
 *              demultiplexed here to handle the different types of fields
 *              (buffer_field, region_field, index_field, bank_field)
 *
 ******************************************************************************/

static acpi_status
acpi_ex_field_datum_io(union acpi_operand_object *obj_desc,
               u32 field_datum_byte_offset, u64 *value, u32 read_write)
{
    acpi_status status;
    u64 local_value;

    ACPI_FUNCTION_TRACE_U32(ex_field_datum_io, field_datum_byte_offset);

    if (read_write == ACPI_READ) {
        if (!value) {
            local_value = 0;

            /* To support reads without saving return value */
            value = &local_value;
        }

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

        *value = 0;
    }

    /*
     * The four types of fields are:
     *
     * buffer_field - Read/write from/to a Buffer
     * region_field - Read/write from/to a Operation Region.
     * bank_field  - Write to a Bank Register, then read/write from/to an
     *               operation_region
     * index_field - Write to an Index Register, then read/write from/to a
     *               Data Register
     */
    switch (obj_desc->common.type) {
    case ACPI_TYPE_BUFFER_FIELD:
        /*
         * If the buffer_field arguments have not been previously evaluated,
         * evaluate them now and save the results.
         */
        if (!(obj_desc->common.flags & AOPOBJ_DATA_VALID)) {
            status = acpi_ds_get_buffer_field_arguments(obj_desc);
            if (ACPI_FAILURE(status)) {
                return_ACPI_STATUS(status);
            }
        }

        if (read_write == ACPI_READ) {
            /*
             * Copy the data from the source buffer.
             * Length is the field width in bytes.
             */
            ACPI_MEMCPY(value,
                    (obj_desc->buffer_field.buffer_obj)->buffer.
                    pointer +
                    obj_desc->buffer_field.base_byte_offset +
                    field_datum_byte_offset,
                    obj_desc->common_field.access_byte_width);
        } else {
            /*
             * Copy the data to the target buffer.
             * Length is the field width in bytes.
             */
            ACPI_MEMCPY((obj_desc->buffer_field.buffer_obj)->buffer.
                    pointer +
                    obj_desc->buffer_field.base_byte_offset +
                    field_datum_byte_offset, value,
                    obj_desc->common_field.access_byte_width);
        }

        status = AE_OK;
        break;

    case ACPI_TYPE_LOCAL_BANK_FIELD:

        /*
         * Ensure that the bank_value is not beyond the capacity of
         * the register
         */
        if (acpi_ex_register_overflow(obj_desc->bank_field.bank_obj,
                          (u64) obj_desc->bank_field.
                          value)) {
            return_ACPI_STATUS(AE_AML_REGISTER_LIMIT);
        }

        /*
         * For bank_fields, we must write the bank_value to the bank_register
         * (itself a region_field) before we can access the data.
         */
        status =
            acpi_ex_insert_into_field(obj_desc->bank_field.bank_obj,
                          &obj_desc->bank_field.value,
                          sizeof(obj_desc->bank_field.
                             value));
        if (ACPI_FAILURE(status)) {
            return_ACPI_STATUS(status);
        }

        /*
         * Now that the Bank has been selected, fall through to the
         * region_field case and write the datum to the Operation Region
         */

        /*lint -fallthrough */

    case ACPI_TYPE_LOCAL_REGION_FIELD:
        /*
         * For simple region_fields, we just directly access the owning
         * Operation Region.
         */
        status =
            acpi_ex_access_region(obj_desc, field_datum_byte_offset,
                      value, read_write);
        break;

    case ACPI_TYPE_LOCAL_INDEX_FIELD:

        /*
         * Ensure that the index_value is not beyond the capacity of
         * the register
         */
        if (acpi_ex_register_overflow(obj_desc->index_field.index_obj,
                          (u64) obj_desc->index_field.
                          value)) {
            return_ACPI_STATUS(AE_AML_REGISTER_LIMIT);
        }

        /* Write the index value to the index_register (itself a region_field) */

        field_datum_byte_offset += obj_desc->index_field.value;

        ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
                  "Write to Index Register: Value %8.8X\n",
                  field_datum_byte_offset));

        status =
            acpi_ex_insert_into_field(obj_desc->index_field.index_obj,
                          &field_datum_byte_offset,
                          sizeof(field_datum_byte_offset));
        if (ACPI_FAILURE(status)) {
            return_ACPI_STATUS(status);
        }

        if (read_write == ACPI_READ) {

            /* Read the datum from the data_register */

            ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
                      "Read from Data Register\n"));

            status =
                acpi_ex_extract_from_field(obj_desc->index_field.
                               data_obj, value,
                               sizeof(u64));
        } else {
            /* Write the datum to the data_register */

            ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
                      "Write to Data Register: Value %8.8X%8.8X\n",
                      ACPI_FORMAT_UINT64(*value)));

            status =
                acpi_ex_insert_into_field(obj_desc->index_field.
                              data_obj, value,
                              sizeof(u64));
        }
        break;

    default:

        ACPI_ERROR((AE_INFO, "Wrong object type in field I/O %u",
                obj_desc->common.type));
        status = AE_AML_INTERNAL;
        break;
    }

    if (ACPI_SUCCESS(status)) {
        if (read_write == ACPI_READ) {
            ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
                      "Value Read %8.8X%8.8X, Width %u\n",
                      ACPI_FORMAT_UINT64(*value),
                      obj_desc->common_field.
                      access_byte_width));
        } else {
            ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
                      "Value Written %8.8X%8.8X, Width %u\n",
                      ACPI_FORMAT_UINT64(*value),
                      obj_desc->common_field.
                      access_byte_width));
        }
    }

    return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_write_with_update_rule
 *
 * PARAMETERS:  obj_desc                - Field to be written
 *              mask                    - bitmask within field datum
 *              field_value             - Value to write
 *              field_datum_byte_offset - Offset of datum within field
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Apply the field update rule to a field write
 *
 ******************************************************************************/

acpi_status
acpi_ex_write_with_update_rule(union acpi_operand_object *obj_desc,
                   u64 mask,
                   u64 field_value, u32 field_datum_byte_offset)
{
    acpi_status status = AE_OK;
    u64 merged_value;
    u64 current_value;

    ACPI_FUNCTION_TRACE_U32(ex_write_with_update_rule, mask);

    /* Start with the new bits  */

    merged_value = field_value;

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

    if (mask != ACPI_UINT64_MAX) {

        /* Decode the update rule */

        switch (obj_desc->common_field.
            field_flags & AML_FIELD_UPDATE_RULE_MASK) {
        case AML_FIELD_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 << (ACPI_MUL_8(sizeof(mask)) -
                       ACPI_MUL_8(obj_desc->common_field.
                          access_byte_width))) != 0) {
                /*
                 * Read the current contents of the byte/word/dword containing
                 * the field, and merge with the new field value.
                 */
                status =
                    acpi_ex_field_datum_io(obj_desc,
                               field_datum_byte_offset,
                               &current_value,
                               ACPI_READ);
                if (ACPI_FAILURE(status)) {
                    return_ACPI_STATUS(status);
                }

                merged_value |= (current_value & ~mask);
            }
            break;

        case AML_FIELD_UPDATE_WRITE_AS_ONES:

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

            merged_value |= ~mask;
            break;

        case AML_FIELD_UPDATE_WRITE_AS_ZEROS:

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

            merged_value &= mask;
            break;

        default:

            ACPI_ERROR((AE_INFO,
                    "Unknown UpdateRule value: 0x%X",
                    (obj_desc->common_field.
                     field_flags &
                     AML_FIELD_UPDATE_RULE_MASK)));
            return_ACPI_STATUS(AE_AML_OPERAND_VALUE);
        }
    }

    ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
              "Mask %8.8X%8.8X, DatumOffset %X, Width %X, Value %8.8X%8.8X, MergedValue %8.8X%8.8X\n",
              ACPI_FORMAT_UINT64(mask),
              field_datum_byte_offset,
              obj_desc->common_field.access_byte_width,
              ACPI_FORMAT_UINT64(field_value),
              ACPI_FORMAT_UINT64(merged_value)));

    /* Write the merged value */

    status = acpi_ex_field_datum_io(obj_desc, field_datum_byte_offset,
                    &merged_value, ACPI_WRITE);

    return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_extract_from_field
 *
 * PARAMETERS:  obj_desc            - Field to be read
 *              buffer              - Where to store the field data
 *              buffer_length       - Length of Buffer
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Retrieve the current value of the given field
 *
 ******************************************************************************/

acpi_status
acpi_ex_extract_from_field(union acpi_operand_object *obj_desc,
               void *buffer, u32 buffer_length)
{
    acpi_status status;
    u64 raw_datum;
    u64 merged_datum;
    u32 field_offset = 0;
    u32 buffer_offset = 0;
    u32 buffer_tail_bits;
    u32 datum_count;
    u32 field_datum_count;
    u32 access_bit_width;
    u32 i;

    ACPI_FUNCTION_TRACE(ex_extract_from_field);

    /* Validate target buffer and clear it */

    if (buffer_length <
        ACPI_ROUND_BITS_UP_TO_BYTES(obj_desc->common_field.bit_length)) {
        ACPI_ERROR((AE_INFO,
                "Field size %u (bits) is too large for buffer (%u)",
                obj_desc->common_field.bit_length, buffer_length));

        return_ACPI_STATUS(AE_BUFFER_OVERFLOW);
    }

    ACPI_MEMSET(buffer, 0, buffer_length);
    access_bit_width = ACPI_MUL_8(obj_desc->common_field.access_byte_width);

    /* Handle the simple case here */

    if ((obj_desc->common_field.start_field_bit_offset == 0) &&
        (obj_desc->common_field.bit_length == access_bit_width)) {
        status = acpi_ex_field_datum_io(obj_desc, 0, buffer, ACPI_READ);
        return_ACPI_STATUS(status);
    }

/* TBD: Move to common setup code */

    /* Field algorithm is limited to sizeof(u64), truncate if needed */

    if (obj_desc->common_field.access_byte_width > sizeof(u64)) {
        obj_desc->common_field.access_byte_width = sizeof(u64);
        access_bit_width = sizeof(u64) * 8;
    }

    /* Compute the number of datums (access width data items) */

    datum_count =
        ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length,
                 access_bit_width);

    field_datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length +
                         obj_desc->common_field.
                         start_field_bit_offset,
                         access_bit_width);

    /* Priming read from the field */

    status =
        acpi_ex_field_datum_io(obj_desc, field_offset, &raw_datum,
                   ACPI_READ);
    if (ACPI_FAILURE(status)) {
        return_ACPI_STATUS(status);
    }
    merged_datum =
        raw_datum >> obj_desc->common_field.start_field_bit_offset;

    /* Read the rest of the field */

    for (i = 1; i < field_datum_count; i++) {

        /* Get next input datum from the field */

        field_offset += obj_desc->common_field.access_byte_width;
        status = acpi_ex_field_datum_io(obj_desc, field_offset,
                        &raw_datum, ACPI_READ);
        if (ACPI_FAILURE(status)) {
            return_ACPI_STATUS(status);
        }

        /*
         * Merge with previous datum if necessary.
         *
         * Note: Before the shift, check if the shift value will be larger than
         * the integer size. If so, there is no need to perform the operation.
         * This avoids the differences in behavior between different compilers
         * concerning shift values larger than the target data width.
         */
        if (access_bit_width -
            obj_desc->common_field.start_field_bit_offset <
            ACPI_INTEGER_BIT_SIZE) {
            merged_datum |=
                raw_datum << (access_bit_width -
                      obj_desc->common_field.
                      start_field_bit_offset);
        }

        if (i == datum_count) {
            break;
        }

        /* Write merged datum to target buffer */

        ACPI_MEMCPY(((char *)buffer) + buffer_offset, &merged_datum,
                ACPI_MIN(obj_desc->common_field.access_byte_width,
                     buffer_length - buffer_offset));

        buffer_offset += obj_desc->common_field.access_byte_width;
        merged_datum =
            raw_datum >> obj_desc->common_field.start_field_bit_offset;
    }

    /* Mask off any extra bits in the last datum */

    buffer_tail_bits = obj_desc->common_field.bit_length % access_bit_width;
    if (buffer_tail_bits) {
        merged_datum &= ACPI_MASK_BITS_ABOVE(buffer_tail_bits);
    }

    /* Write the last datum to the buffer */

    ACPI_MEMCPY(((char *)buffer) + buffer_offset, &merged_datum,
            ACPI_MIN(obj_desc->common_field.access_byte_width,
                 buffer_length - buffer_offset));

    return_ACPI_STATUS(AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_insert_into_field
 *
 * PARAMETERS:  obj_desc            - Field to be written
 *              buffer              - Data to be written
 *              buffer_length       - Length of Buffer
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Store the Buffer contents into the given field
 *
 ******************************************************************************/

acpi_status
acpi_ex_insert_into_field(union acpi_operand_object *obj_desc,
              void *buffer, u32 buffer_length)
{
    void *new_buffer;
    acpi_status status;
    u64 mask;
    u64 width_mask;
    u64 merged_datum;
    u64 raw_datum = 0;
    u32 field_offset = 0;
    u32 buffer_offset = 0;
    u32 buffer_tail_bits;
    u32 datum_count;
    u32 field_datum_count;
    u32 access_bit_width;
    u32 required_length;
    u32 i;

    ACPI_FUNCTION_TRACE(ex_insert_into_field);

    /* Validate input buffer */

    new_buffer = NULL;
    required_length =
        ACPI_ROUND_BITS_UP_TO_BYTES(obj_desc->common_field.bit_length);
    /*
     * We must have a buffer that is at least as long as the field
     * we are writing to.  This is because individual fields are
     * indivisible and partial writes are not supported -- as per
     * the ACPI specification.
     */
    if (buffer_length < required_length) {

        /* We need to create a new buffer */

        new_buffer = ACPI_ALLOCATE_ZEROED(required_length);
        if (!new_buffer) {
            return_ACPI_STATUS(AE_NO_MEMORY);
        }

        /*
         * Copy the original data to the new buffer, starting
         * at Byte zero.  All unused (upper) bytes of the
         * buffer will be 0.
         */
        ACPI_MEMCPY((char *)new_buffer, (char *)buffer, buffer_length);
        buffer = new_buffer;
        buffer_length = required_length;
    }

/* TBD: Move to common setup code */

    /* Algo is limited to sizeof(u64), so cut the access_byte_width */
    if (obj_desc->common_field.access_byte_width > sizeof(u64)) {
        obj_desc->common_field.access_byte_width = sizeof(u64);
    }

    access_bit_width = ACPI_MUL_8(obj_desc->common_field.access_byte_width);

    /*
     * Create the bitmasks used for bit insertion.
     * Note: This if/else is used to bypass compiler differences with the
     * shift operator
     */
    if (access_bit_width == ACPI_INTEGER_BIT_SIZE) {
        width_mask = ACPI_UINT64_MAX;
    } else {
        width_mask = ACPI_MASK_BITS_ABOVE(access_bit_width);
    }

    mask = width_mask &
        ACPI_MASK_BITS_BELOW(obj_desc->common_field.start_field_bit_offset);

    /* Compute the number of datums (access width data items) */

    datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length,
                       access_bit_width);

    field_datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length +
                         obj_desc->common_field.
                         start_field_bit_offset,
                         access_bit_width);

    /* Get initial Datum from the input buffer */

    ACPI_MEMCPY(&raw_datum, buffer,
            ACPI_MIN(obj_desc->common_field.access_byte_width,
                 buffer_length - buffer_offset));

    merged_datum =
        raw_datum << obj_desc->common_field.start_field_bit_offset;

    /* Write the entire field */

    for (i = 1; i < field_datum_count; i++) {

        /* Write merged datum to the target field */

        merged_datum &= mask;
        status = acpi_ex_write_with_update_rule(obj_desc, mask,
                            merged_datum,
                            field_offset);
        if (ACPI_FAILURE(status)) {
            goto exit;
        }

        field_offset += obj_desc->common_field.access_byte_width;

        /*
         * Start new output datum by merging with previous input datum
         * if necessary.
         *
         * Note: Before the shift, check if the shift value will be larger than
         * the integer size. If so, there is no need to perform the operation.
         * This avoids the differences in behavior between different compilers
         * concerning shift values larger than the target data width.
         */
        if ((access_bit_width -
             obj_desc->common_field.start_field_bit_offset) <
            ACPI_INTEGER_BIT_SIZE) {
            merged_datum =
                raw_datum >> (access_bit_width -
                      obj_desc->common_field.
                      start_field_bit_offset);
        } else {
            merged_datum = 0;
        }

        mask = width_mask;

        if (i == datum_count) {
            break;
        }

        /* Get the next input datum from the buffer */

        buffer_offset += obj_desc->common_field.access_byte_width;
        ACPI_MEMCPY(&raw_datum, ((char *)buffer) + buffer_offset,
                ACPI_MIN(obj_desc->common_field.access_byte_width,
                     buffer_length - buffer_offset));

        merged_datum |=
            raw_datum << obj_desc->common_field.start_field_bit_offset;
    }

    /* Mask off any extra bits in the last datum */

    buffer_tail_bits = (obj_desc->common_field.bit_length +
                obj_desc->common_field.start_field_bit_offset) %
        access_bit_width;
    if (buffer_tail_bits) {
        mask &= ACPI_MASK_BITS_ABOVE(buffer_tail_bits);
    }

    /* Write the last datum to the field */

    merged_datum &= mask;
    status = acpi_ex_write_with_update_rule(obj_desc,
                        mask, merged_datum,
                        field_offset);

      exit:
    /* Free temporary buffer if we used one */

    if (new_buffer) {
        ACPI_FREE(new_buffer);
    }
    return_ACPI_STATUS(status);
}