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/******************************************************************************

 *

 * Module Name: exfldio - Aml Field I/O

 *

 *****************************************************************************/

/*

 * 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 

#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 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 %8.8X%8.8X\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_FORMAT_UINT64(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)

{

	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.

			 */

			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.

			 */

			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,

							   ¤t_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);

	}

	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)) {

		if (buffer_length >= sizeof(u64)) {

			status =

			    acpi_ex_field_datum_io(obj_desc, 0, buffer,

						   ACPI_READ);

		} else {

			/* Use raw_datum (u64) to handle buffers < 64 bits */

			status =

			    acpi_ex_field_datum_io(obj_desc, 0, &raw_datum,

						   ACPI_READ);

			memcpy(buffer, &raw_datum, buffer_length);

		}

		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 */

		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 */

	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.

		 */

		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 */

	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;

		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);

}