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

/*
 * Copyright (C) 2000 - 2004, R. Byron Moore
 * 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 <acpi/acinterp.h>
#include <acpi/amlcode.h>
#include <acpi/acevents.h>
#include <acpi/acdispat.h>


#define _COMPONENT          ACPI_EXECUTER
	 ACPI_MODULE_NAME    ("exfldio")


/*******************************************************************************
 *
 * 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.
 *
 ******************************************************************************/

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;


	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 (ACPI_GET_OBJECT_TYPE (rgn_desc) != ACPI_TYPE_REGION) {
		ACPI_DEBUG_PRINT ((ACPI_DB_ERROR, "Needed Region, found type %X (%s)\n",
			ACPI_GET_OBJECT_TYPE (rgn_desc),
			acpi_ut_get_object_type_name (rgn_desc)));

		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 (!(rgn_desc->common.flags & AOPOBJ_DATA_VALID)) {
		status = acpi_ds_get_region_arguments (rgn_desc);
		if (ACPI_FAILURE (status)) {
			return_ACPI_STATUS (status);
		}
	}

	if (rgn_desc->region.space_id == ACPI_ADR_SPACE_SMBUS) {
		/* SMBus 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.
			 */
			if (ACPI_ROUND_UP (rgn_desc->region.length,
					   obj_desc->common_field.access_byte_width) >=
				(obj_desc->common_field.base_byte_offset +
				 (acpi_native_uint) 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_DEBUG_PRINT ((ACPI_DB_ERROR,
				"Field [%4.4s] access width (%d bytes) too large for region [%4.4s] (length %X)\n",
				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_DEBUG_PRINT ((ACPI_DB_ERROR,
			"Field [%4.4s] Base+Offset+Width %X+%X+%X is beyond end of region [%4.4s] (length %X)\n",
			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
 *                                        the size of acpi_integer)
 *              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,
	acpi_integer                    *value,
	u32                             function)
{
	acpi_status                     status;
	union acpi_operand_object       *rgn_desc;
	acpi_physical_address           address;


	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;
	address = rgn_desc->region.address
			 + 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, byte_base %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 (address)));

	/* Invoke the appropriate address_space/op_region handler */

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

	if (ACPI_FAILURE (status)) {
		if (status == AE_NOT_IMPLEMENTED) {
			ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
				"Region %s(%X) not implemented\n",
				acpi_ut_get_region_name (rgn_desc->region.space_id),
				rgn_desc->region.space_id));
		}
		else if (status == AE_NOT_EXIST) {
			ACPI_REPORT_ERROR ((
				"Region %s(%X) has no handler\n",
				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.
 *
 ******************************************************************************/

u8
acpi_ex_register_overflow (
	union acpi_operand_object       *obj_desc,
	acpi_integer                    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 >= ((acpi_integer) 1 << obj_desc->common_field.bit_length)) {
		/*
		 * The Value is larger than the maximum value that can fit into
		 * the register.
		 */
		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)
 *
 ******************************************************************************/

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


	ACPI_FUNCTION_TRACE_U32 ("ex_field_datum_io", field_datum_byte_offset);


	if (read_write == ACPI_READ) {
		if (!value) {
			local_value = 0;
			value = &local_value; /* To support reads without saving return 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 op_region
	 * index_field - Write to an Index Register, then read/write from/to a Data Register
	 */
	switch (ACPI_GET_OBJECT_TYPE (obj_desc)) {
	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,
				  (acpi_integer) 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,
				  (acpi_integer) 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);
		}

		ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
				"I/O to Data Register: value_ptr %p\n",
				value));

		if (read_write == ACPI_READ) {
			/* Read the datum from the data_register */

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

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


	default:

		ACPI_REPORT_ERROR (("Wrong object type in field I/O %X\n",
			ACPI_GET_OBJECT_TYPE (obj_desc)));
		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 %d\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 %d\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 set
 *              Value               - Value to store
 *
 * 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,
	acpi_integer                    mask,
	acpi_integer                    field_value,
	u32                             field_datum_byte_offset)
{
	acpi_status                     status = AE_OK;
	acpi_integer                    merged_value;
	acpi_integer                    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_INTEGER_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_DEBUG_PRINT ((ACPI_DB_ERROR,
				"write_with_update_rule: Unknown update_rule setting: %X\n",
				(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, datum_offset %X, Width %X, Value %8.8X%8.8X, merged_value %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_get_buffer_datum
 *
 * PARAMETERS:  Datum               - Where the Datum is returned
 *              Buffer              - Raw field buffer
 *              buffer_length       - Entire length (used for big-endian only)
 *              byte_granularity    - 1/2/4/8 Granularity of the field
 *                                    (aka Datum Size)
 *              buffer_offset       - Datum offset into the buffer
 *
 * RETURN:      none
 *
 * DESCRIPTION: Get a datum from the buffer according to the buffer field
 *              byte granularity
 *
 ******************************************************************************/

void
acpi_ex_get_buffer_datum (
	acpi_integer                    *datum,
	void                            *buffer,
	u32                             buffer_length,
	u32                             byte_granularity,
	u32                             buffer_offset)
{
	u32                             index;


	ACPI_FUNCTION_TRACE_U32 ("ex_get_buffer_datum", byte_granularity);


	/* Get proper index into buffer (handles big/little endian) */

	index = ACPI_BUFFER_INDEX (buffer_length, buffer_offset, byte_granularity);

	/* Move the requested number of bytes */

	switch (byte_granularity) {
	case ACPI_FIELD_BYTE_GRANULARITY:

		*datum = ((u8 *) buffer) [index];
		break;

	case ACPI_FIELD_WORD_GRANULARITY:

		ACPI_MOVE_16_TO_64 (datum, &(((u16 *) buffer) [index]));
		break;

	case ACPI_FIELD_DWORD_GRANULARITY:

		ACPI_MOVE_32_TO_64 (datum, &(((u32 *) buffer) [index]));
		break;

	case ACPI_FIELD_QWORD_GRANULARITY:

		ACPI_MOVE_64_TO_64 (datum, &(((u64 *) buffer) [index]));
		break;

	default:
		/* Should not get here */
		break;
	}

	return_VOID;
}


/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_set_buffer_datum
 *
 * PARAMETERS:  merged_datum        - Value to store
 *              Buffer              - Receiving buffer
 *              buffer_length       - Entire length (used for big-endian only)
 *              byte_granularity    - 1/2/4/8 Granularity of the field
 *                                    (aka Datum Size)
 *              buffer_offset       - Datum offset into the buffer
 *
 * RETURN:      none
 *
 * DESCRIPTION: Store the merged datum to the buffer according to the
 *              byte granularity
 *
 ******************************************************************************/

void
acpi_ex_set_buffer_datum (
	acpi_integer                    merged_datum,
	void                            *buffer,
	u32                             buffer_length,
	u32                             byte_granularity,
	u32                             buffer_offset)
{
	u32                             index;


	ACPI_FUNCTION_TRACE_U32 ("ex_set_buffer_datum", byte_granularity);


	/* Get proper index into buffer (handles big/little endian) */

	index = ACPI_BUFFER_INDEX (buffer_length, buffer_offset, byte_granularity);

	/* Move the requested number of bytes */

	switch (byte_granularity) {
	case ACPI_FIELD_BYTE_GRANULARITY:

		((u8 *) buffer) [index] = (u8) merged_datum;
		break;

	case ACPI_FIELD_WORD_GRANULARITY:

		ACPI_MOVE_64_TO_16 (&(((u16 *) buffer)[index]), &merged_datum);
		break;

	case ACPI_FIELD_DWORD_GRANULARITY:

		ACPI_MOVE_64_TO_32 (&(((u32 *) buffer)[index]), &merged_datum);
		break;

	case ACPI_FIELD_QWORD_GRANULARITY:

		ACPI_MOVE_64_TO_64 (&(((u64 *) buffer)[index]), &merged_datum);
		break;

	default:
		/* Should not get here */
		break;
	}

	return_VOID;
}


/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_common_buffer_setup
 *
 * PARAMETERS:  obj_desc            - Field object
 *              buffer_length       - Length of caller's buffer
 *              datum_count         - Where the datum_count is returned
 *
 * RETURN:      Status, datum_count
 *
 * DESCRIPTION: Common code to validate the incoming buffer size and compute
 *              the number of field "datums" that must be read or written.
 *              A "datum" is the smallest unit that can be read or written
 *              to the field, it is either 1,2,4, or 8 bytes.
 *
 ******************************************************************************/

acpi_status
acpi_ex_common_buffer_setup (
	union acpi_operand_object       *obj_desc,
	u32                             buffer_length,
	u32                             *datum_count)
{
	u32                             byte_field_length;
	u32                             actual_byte_field_length;


	ACPI_FUNCTION_TRACE ("ex_common_buffer_setup");


	/*
	 * Incoming buffer must be at least as long as the field, we do not
	 * allow "partial" field reads/writes.  We do not care if the buffer is
	 * larger than the field, this typically happens when an integer is
	 * read/written to a field that is actually smaller than an integer.
	 */
	byte_field_length = ACPI_ROUND_BITS_UP_TO_BYTES (
			 obj_desc->common_field.bit_length);
	if (byte_field_length > buffer_length) {
		ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
			"Field size %X (bytes) is too large for buffer (%X)\n",
			byte_field_length, buffer_length));

		return_ACPI_STATUS (AE_BUFFER_OVERFLOW);
	}

	/*
	 * Create "actual" field byte count (minimum number of bytes that
	 * must be read), then convert to datum count (minimum number
	 * of datum-sized units that must be read)
	 */
	actual_byte_field_length = ACPI_ROUND_BITS_UP_TO_BYTES (
			  obj_desc->common_field.start_field_bit_offset +
			  obj_desc->common_field.bit_length);


	*datum_count = ACPI_ROUND_UP_TO (actual_byte_field_length,
			   obj_desc->common_field.access_byte_width);

	ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
		"buffer_bytes %X, actual_bytes %X, Datums %X, byte_gran %X\n",
		byte_field_length, actual_byte_field_length,
		*datum_count, obj_desc->common_field.access_byte_width));

	return_ACPI_STATUS (AE_OK);
}


/*******************************************************************************
 *
 * 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;
	u32                             field_datum_byte_offset;
	u32                             buffer_datum_offset;
	acpi_integer                    previous_raw_datum = 0;
	acpi_integer                    this_raw_datum = 0;
	acpi_integer                    merged_datum = 0;
	u32                             datum_count;
	u32                             i;


	ACPI_FUNCTION_TRACE ("ex_extract_from_field");


	/* Validate buffer, compute number of datums */

	status = acpi_ex_common_buffer_setup (obj_desc, buffer_length, &datum_count);
	if (ACPI_FAILURE (status)) {
		return_ACPI_STATUS (status);
	}

	/*
	 * Clear the caller's buffer (the whole buffer length as given)
	 * This is very important, especially in the cases where the buffer
	 * is longer than the size of the field.
	 */
	ACPI_MEMSET (buffer, 0, buffer_length);

	field_datum_byte_offset = 0;
	buffer_datum_offset= 0;

	/* Read the entire field */

	for (i = 0; i < datum_count; i++) {
		status = acpi_ex_field_datum_io (obj_desc, field_datum_byte_offset,
				  &this_raw_datum, ACPI_READ);
		if (ACPI_FAILURE (status)) {
			return_ACPI_STATUS (status);
		}

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

		if ((datum_count == 1) &&
			(obj_desc->common_field.flags & AOPOBJ_SINGLE_DATUM)) {
			/* 1) Shift the valid data bits down to start at bit 0 */

			merged_datum = (this_raw_datum >> obj_desc->common_field.start_field_bit_offset);

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

			if (obj_desc->common_field.end_buffer_valid_bits) {
				merged_datum &= ACPI_MASK_BITS_ABOVE (obj_desc->common_field.end_buffer_valid_bits);
			}

			/* Store the datum to the caller buffer */

			acpi_ex_set_buffer_datum (merged_datum, buffer, buffer_length,
					obj_desc->common_field.access_byte_width, buffer_datum_offset);

			return_ACPI_STATUS (AE_OK);
		}

		/* Special handling for the last datum to ignore extra bits */

		if ((i >= (datum_count -1))          &&
			(obj_desc->common_field.end_field_valid_bits)) {
			/*
			 * This is the last iteration of the loop.  We need to clear
			 * any unused bits (bits that are not part of this field) before
			 * we store the final merged datum into the caller buffer.
			 */
			this_raw_datum &=
				ACPI_MASK_BITS_ABOVE (obj_desc->common_field.end_field_valid_bits);
		}

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

			acpi_ex_set_buffer_datum (this_raw_datum, buffer, buffer_length,
					obj_desc->common_field.access_byte_width, buffer_datum_offset);
			buffer_datum_offset++;
		}
		else {
			/* Not aligned -- on the first iteration, just save the datum */

			if (i != 0) {
				/*
				 * 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
				 */
				merged_datum = (previous_raw_datum >> obj_desc->common_field.start_field_bit_offset);

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

				merged_datum |= (this_raw_datum << obj_desc->common_field.datum_valid_bits);

				acpi_ex_set_buffer_datum (merged_datum, buffer, buffer_length,
						obj_desc->common_field.access_byte_width, buffer_datum_offset);
				buffer_datum_offset++;
			}

			/*
			 * Save the raw datum that was just acquired since it may contain bits
			 * of the *next* field datum
			 */
			previous_raw_datum = this_raw_datum;
		}

		field_datum_byte_offset += obj_desc->common_field.access_byte_width;
	}

	/* For non-aligned case, there is one last datum to insert */

	if (obj_desc->common_field.start_field_bit_offset != 0) {
		merged_datum = (this_raw_datum >> obj_desc->common_field.start_field_bit_offset);

		acpi_ex_set_buffer_datum (merged_datum, buffer, buffer_length,
				obj_desc->common_field.access_byte_width, buffer_datum_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)
{
	acpi_status                     status;
	u32                             field_datum_byte_offset;
	u32                             datum_offset;
	acpi_integer                    mask;
	acpi_integer                    merged_datum;
	acpi_integer                    previous_raw_datum;
	acpi_integer                    this_raw_datum;
	u32                             datum_count;


	ACPI_FUNCTION_TRACE ("ex_insert_into_field");


	/* Validate buffer, compute number of datums */

	status = acpi_ex_common_buffer_setup (obj_desc, buffer_length, &datum_count);
	if (ACPI_FAILURE (status)) {
		return_ACPI_STATUS (status);
	}

	/*
	 * 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
	 */
	field_datum_byte_offset = 0;
	datum_offset= 0;

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

	acpi_ex_get_buffer_datum (&previous_raw_datum, buffer, buffer_length,
			obj_desc->common_field.access_byte_width, datum_offset);

	/*
	 * 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 bit_length are valid for a shift operation)
	 *
	 * Mask off bits that are "below" the field (if any)
	 */
	mask = ACPI_MASK_BITS_BELOW (obj_desc->common_field.start_field_bit_offset);

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

	if ((obj_desc->common_field.flags & AOPOBJ_SINGLE_DATUM) &&
		 obj_desc->common_field.end_field_valid_bits) {
		/* There are bits above the field, mask them off also */

		mask &= ACPI_MASK_BITS_ABOVE (obj_desc->common_field.end_field_valid_bits);
	}

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

	merged_datum = (previous_raw_datum << obj_desc->common_field.start_field_bit_offset);
	merged_datum &= mask;

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

	status = acpi_ex_write_with_update_rule (obj_desc, mask, merged_datum,
			   field_datum_byte_offset);
	if (ACPI_FAILURE (status)) {
		return_ACPI_STATUS (status);
	}

	/* We just wrote the first datum */

	datum_offset++;

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

	if ((datum_count == 1) &&
	   (obj_desc->common_field.flags & AOPOBJ_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 (datum_offset < datum_count) {
		field_datum_byte_offset += obj_desc->common_field.access_byte_width;

		/*
		 * Get the next raw buffer datum.  It may contain bits of the previous
		 * field datum
		 */
		acpi_ex_get_buffer_datum (&this_raw_datum, buffer, buffer_length,
				obj_desc->common_field.access_byte_width, datum_offset);

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

		if (obj_desc->common_field.start_field_bit_offset != 0) {
			/*
			 * Put together appropriate bits of the two raw buffer data to make
			 * a single complete field datum
			 */
			merged_datum =
				(previous_raw_datum >> obj_desc->common_field.datum_valid_bits) |
				(this_raw_datum << obj_desc->common_field.start_field_bit_offset);
		}
		else {
			/* Field began aligned on datum boundary */

			merged_datum = this_raw_datum;
		}

		/*
		 * 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.
		 */
		datum_offset++;
		if ((datum_offset == datum_count) &&
			(obj_desc->common_field.end_field_valid_bits)) {
			/*
			 * If there are dangling non-aligned bits, perform one more merged write
			 * Else - field is aligned at the end, no need for any more writes
			 */

			/*
			 * 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 = ACPI_MASK_BITS_ABOVE (obj_desc->common_field.end_field_valid_bits);
			merged_datum &= mask;

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

			status = acpi_ex_write_with_update_rule (obj_desc, mask, merged_datum,
					   field_datum_byte_offset);
			if (ACPI_FAILURE (status)) {
				return_ACPI_STATUS (status);
			}
		}
		else {
			/* Normal (aligned) case -- write the completed datum */

			status = acpi_ex_field_datum_io (obj_desc, field_datum_byte_offset,
					  &merged_datum, ACPI_WRITE);
			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.
		 */
		previous_raw_datum = this_raw_datum;
	}

	return_ACPI_STATUS (status);
}


