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/******************************************************************************
*
* Module Name: exfldio - Aml Field I/O
* $Revision: 66 $
*
*****************************************************************************/
/*
* Copyright (C) 2000, 2001 R. Byron Moore
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "acpi.h"
#include "acinterp.h"
#include "amlcode.h"
#include "acnamesp.h"
#include "achware.h"
#include "acevents.h"
#include "acdispat.h"
#define _COMPONENT ACPI_EXECUTER
MODULE_NAME ("exfldio")
/*******************************************************************************
*
* FUNCTION: Acpi_ex_setup_field
*
* PARAMETERS: *Obj_desc - Field to be read or written
* Field_datum_byte_offset - Current offset into the field
*
* RETURN: Status
*
* DESCRIPTION: Common processing for Acpi_ex_extract_from_field and
* Acpi_ex_insert_into_field
*
******************************************************************************/
acpi_status
acpi_ex_setup_field (
acpi_operand_object *obj_desc,
u32 field_datum_byte_offset)
{
acpi_status status = AE_OK;
acpi_operand_object *rgn_desc;
FUNCTION_TRACE_U32 ("Ex_setup_field", field_datum_byte_offset);
rgn_desc = obj_desc->common_field.region_obj;
if (ACPI_TYPE_REGION != rgn_desc->common.type) {
ACPI_DEBUG_PRINT ((ACPI_DB_ERROR, "Needed Region, found type %x %s\n",
rgn_desc->common.type, acpi_ut_get_type_name (rgn_desc->common.type)));
return_ACPI_STATUS (AE_AML_OPERAND_TYPE);
}
/*
* If the Region Address and Length have not been previously evaluated,
* evaluate them now and save the results.
*/
if (!(rgn_desc->region.flags & AOPOBJ_DATA_VALID)) {
status = acpi_ds_get_region_arguments (rgn_desc);
if (ACPI_FAILURE (status)) {
return_ACPI_STATUS (status);
}
}
/*
* Validate the request. The entire request from the byte offset for a
* length of one field datum (access width) must fit within the region.
* (Region length is specified in bytes)
*/
if (rgn_desc->region.length < (obj_desc->common_field.base_byte_offset +
field_datum_byte_offset +
obj_desc->common_field.access_byte_width)) {
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 access width (%d bytes) too large for region size (%X)\n",
obj_desc->common_field.access_byte_width, 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 base+offset+width %X+%X+%X exceeds region size (%X bytes) field=%p region=%p\n",
obj_desc->common_field.base_byte_offset, field_datum_byte_offset,
obj_desc->common_field.access_byte_width,
rgn_desc->region.length, obj_desc, rgn_desc));
return_ACPI_STATUS (AE_AML_REGION_LIMIT);
}
return_ACPI_STATUS (AE_OK);
}
/*******************************************************************************
*
* FUNCTION: Acpi_ex_read_field_datum
*
* PARAMETERS: *Obj_desc - Field to be read
* *Value - Where to store value (must be 32 bits)
*
* RETURN: Status
*
* DESCRIPTION: Retrieve the value of the given field
*
******************************************************************************/
acpi_status
acpi_ex_read_field_datum (
acpi_operand_object *obj_desc,
u32 field_datum_byte_offset,
u32 *value)
{
acpi_status status;
acpi_operand_object *rgn_desc;
ACPI_PHYSICAL_ADDRESS address;
u32 local_value;
FUNCTION_TRACE_U32 ("Ex_read_field_datum", field_datum_byte_offset);
if (!value) {
local_value = 0;
value = &local_value; /* support reads without saving value */
}
/* Clear the entire return buffer first, [Very Important!] */
*value = 0;
/*
* Buffer_fields - Read from a Buffer
* Other Fields - Read from a Operation Region.
*/
switch (obj_desc->common.type) {
case ACPI_TYPE_BUFFER_FIELD:
/*
* For Buffer_fields, we only need to 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);
status = AE_OK;
break;
case INTERNAL_TYPE_REGION_FIELD:
case INTERNAL_TYPE_BANK_FIELD:
/*
* For other fields, we need to go through an Operation Region
* (Only types that will get here are Region_fields and Bank_fields)
*/
status = acpi_ex_setup_field (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;
ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD, "Region %s(%X) width %X base:off %X:%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_bit_width,
obj_desc->common_field.base_byte_offset, field_datum_byte_offset,
HIDWORD(address), LODWORD(address)));
/* Invoke the appropriate Address_space/Op_region handler */
status = acpi_ev_address_space_dispatch (rgn_desc, ACPI_READ_ADR_SPACE,
address, obj_desc->common_field.access_bit_width, value);
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_DEBUG_PRINT ((ACPI_DB_ERROR, "Region %s(%X) has no handler\n",
acpi_ut_get_region_name (rgn_desc->region.space_id),
rgn_desc->region.space_id));
}
break;
default:
ACPI_DEBUG_PRINT ((ACPI_DB_ERROR, "%p, wrong source type - %s\n",
obj_desc, acpi_ut_get_type_name (obj_desc->common.type)));
status = AE_AML_INTERNAL;
break;
}
ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD, "Returned value=%08X \n", *value));
return_ACPI_STATUS (status);
}
/*******************************************************************************
*
* FUNCTION: Acpi_ex_get_buffer_datum
*
* PARAMETERS: Merged_datum - Value to store
* Buffer - Receiving buffer
* Byte_granularity - 1/2/4 Granularity of the field
* (aka Datum Size)
* Offset - Datum offset into the buffer
*
* RETURN: none
*
* DESCRIPTION: Store the merged datum to the buffer according to the
* byte granularity
*
******************************************************************************/
static void
acpi_ex_get_buffer_datum(
u32 *datum,
void *buffer,
u32 byte_granularity,
u32 offset)
{
FUNCTION_ENTRY ();
switch (byte_granularity) {
case ACPI_FIELD_BYTE_GRANULARITY:
*datum = ((u8 *) buffer) [offset];
break;
case ACPI_FIELD_WORD_GRANULARITY:
MOVE_UNALIGNED16_TO_32 (datum, &(((u16 *) buffer) [offset]));
break;
case ACPI_FIELD_DWORD_GRANULARITY:
MOVE_UNALIGNED32_TO_32 (datum, &(((u32 *) buffer) [offset]));
break;
}
}
/*******************************************************************************
*
* FUNCTION: Acpi_ex_set_buffer_datum
*
* PARAMETERS: Merged_datum - Value to store
* Buffer - Receiving buffer
* Byte_granularity - 1/2/4 Granularity of the field
* (aka Datum Size)
* Offset - Datum offset into the buffer
*
* RETURN: none
*
* DESCRIPTION: Store the merged datum to the buffer according to the
* byte granularity
*
******************************************************************************/
static void
acpi_ex_set_buffer_datum (
u32 merged_datum,
void *buffer,
u32 byte_granularity,
u32 offset)
{
FUNCTION_ENTRY ();
switch (byte_granularity) {
case ACPI_FIELD_BYTE_GRANULARITY:
((u8 *) buffer) [offset] = (u8) merged_datum;
break;
case ACPI_FIELD_WORD_GRANULARITY:
MOVE_UNALIGNED16_TO_16 (&(((u16 *) buffer)[offset]), &merged_datum);
break;
case ACPI_FIELD_DWORD_GRANULARITY:
MOVE_UNALIGNED32_TO_32 (&(((u32 *) buffer)[offset]), &merged_datum);
break;
}
}
/*******************************************************************************
*
* FUNCTION: Acpi_ex_extract_from_field
*
* PARAMETERS: *Obj_desc - Field to be read
* *Value - Where to store value
*
* RETURN: Status
*
* DESCRIPTION: Retrieve the value of the given field
*
******************************************************************************/
acpi_status
acpi_ex_extract_from_field (
acpi_operand_object *obj_desc,
void *buffer,
u32 buffer_length)
{
acpi_status status;
u32 field_datum_byte_offset;
u32 datum_offset;
u32 previous_raw_datum;
u32 this_raw_datum = 0;
u32 merged_datum = 0;
u32 byte_field_length;
u32 datum_count;
FUNCTION_TRACE ("Ex_extract_from_field");
/*
* The field must fit within the caller's buffer
*/
byte_field_length = ROUND_BITS_UP_TO_BYTES (obj_desc->common_field.bit_length);
if (byte_field_length > buffer_length) {
ACPI_DEBUG_PRINT ((ACPI_DB_INFO, "Field size %X (bytes) too large for buffer (%X)\n",
byte_field_length, buffer_length));
return_ACPI_STATUS (AE_BUFFER_OVERFLOW);
}
/* Convert field byte count to datum count, round up if necessary */
datum_count = ROUND_UP_TO (byte_field_length, obj_desc->common_field.access_byte_width);
ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
"Byte_len=%x, Datum_len=%x, Bit_gran=%x, Byte_gran=%x\n",
byte_field_length, datum_count, obj_desc->common_field.access_bit_width,
obj_desc->common_field.access_byte_width));
/*
* Clear the caller's buffer (the whole buffer length as given)
* This is very important, especially in the cases where a byte is read,
* but the buffer is really a u32 (4 bytes).
*/
MEMSET (buffer, 0, buffer_length);
/* Read the first raw datum to prime the loop */
field_datum_byte_offset = 0;
datum_offset= 0;
status = acpi_ex_read_field_datum (obj_desc, field_datum_byte_offset, &previous_raw_datum);
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.access_flags & AFIELD_SINGLE_DATUM)) {
/* 1) Shift the valid data bits down to start at bit 0 */
merged_datum = (previous_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 &= 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, obj_desc->common_field.access_byte_width,
datum_offset);
return_ACPI_STATUS (AE_OK);
}
/* We need to get more raw data to complete one or more field data */
while (datum_offset < datum_count) {
field_datum_byte_offset += obj_desc->common_field.access_byte_width;
/*
* If the field is aligned on a byte boundary, we don't want
* to perform a final read, since this would potentially read
* past the end of the region.
*
* TBD: [Investigate] It may make more sense to just split the aligned
* and non-aligned cases since the aligned case is so very simple,
*/
if ((obj_desc->common_field.start_field_bit_offset != 0) ||
((obj_desc->common_field.start_field_bit_offset == 0) &&
(datum_offset < (datum_count -1)))) {
/*
* Get the next raw datum, it contains some or all bits
* of the current field datum
*/
status = acpi_ex_read_field_datum (obj_desc, field_datum_byte_offset, &this_raw_datum);
if (ACPI_FAILURE (status)) {
return_ACPI_STATUS (status);
}
}
/*
* 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 */
merged_datum = previous_raw_datum;
}
else {
/*
* Put together the appropriate bits of the two raw data to make a
* single complete field datum
*
* 1) Normalize the first datum down to bit 0
*/
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);
if ((datum_offset >= (datum_count -1))) {
/*
* This is the last iteration of the loop. We need to clear
* any unused bits (bits that are not part of this field) that
* came from the last raw datum before we store the final
* merged datum into the caller buffer.
*/
if (obj_desc->common_field.end_buffer_valid_bits) {
merged_datum &=
MASK_BITS_ABOVE (obj_desc->common_field.end_buffer_valid_bits);
}
}
}
/*
* Store the merged field datum in the caller's buffer, according to
* the granularity of the field (size of each datum).
*/
acpi_ex_set_buffer_datum (merged_datum, buffer, obj_desc->common_field.access_byte_width,
datum_offset);
/*
* Save the raw datum that was just acquired since it may contain bits
* of the *next* field datum. Update offsets
*/
previous_raw_datum = this_raw_datum;
datum_offset++;
}
return_ACPI_STATUS (AE_OK);
}
/*******************************************************************************
*
* FUNCTION: Acpi_ex_write_field_datum
*
* PARAMETERS: *Obj_desc - Field to be set
* Value - Value to store
*
* RETURN: Status
*
* DESCRIPTION: Store the value into the given field
*
******************************************************************************/
static acpi_status
acpi_ex_write_field_datum (
acpi_operand_object *obj_desc,
u32 field_datum_byte_offset,
u32 value)
{
acpi_status status = AE_OK;
acpi_operand_object *rgn_desc = NULL;
ACPI_PHYSICAL_ADDRESS address;
FUNCTION_TRACE_U32 ("Ex_write_field_datum", field_datum_byte_offset);
/*
* Buffer_fields - Read from a Buffer
* Other Fields - Read from a Operation Region.
*/
switch (obj_desc->common.type) {
case ACPI_TYPE_BUFFER_FIELD:
/*
* For Buffer_fields, we only need to 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 INTERNAL_TYPE_REGION_FIELD:
case INTERNAL_TYPE_BANK_FIELD:
/*
* For other fields, we need to go through an Operation Region
* (Only types that will get here are Region_fields and Bank_fields)
*/
status = acpi_ex_setup_field (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;
ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
"Store %X in Region %s(%X) at %8.8X%8.8X width %X\n",
value, acpi_ut_get_region_name (rgn_desc->region.space_id),
rgn_desc->region.space_id, HIDWORD(address), LODWORD(address),
obj_desc->common_field.access_bit_width));
/* Invoke the appropriate Address_space/Op_region handler */
status = acpi_ev_address_space_dispatch (rgn_desc, ACPI_WRITE_ADR_SPACE,
address, obj_desc->common_field.access_bit_width, &value);
if (status == AE_NOT_IMPLEMENTED) {
ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
"**** Region type %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_DEBUG_PRINT ((ACPI_DB_ERROR,
"**** Region type %s(%X) does not have a handler\n",
acpi_ut_get_region_name (rgn_desc->region.space_id),
rgn_desc->region.space_id));
}
break;
default:
ACPI_DEBUG_PRINT ((ACPI_DB_ERROR, "%p, wrong source type - %s\n",
obj_desc, acpi_ut_get_type_name (obj_desc->common.type)));
status = AE_AML_INTERNAL;
break;
}
ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD, "Value written=%08X \n", value));
return_ACPI_STATUS (status);
}
/*******************************************************************************
*
* FUNCTION: Acpi_ex_write_field_datum_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
*
******************************************************************************/
static acpi_status
acpi_ex_write_field_datum_with_update_rule (
acpi_operand_object *obj_desc,
u32 mask,
u32 field_value,
u32 field_datum_byte_offset)
{
acpi_status status = AE_OK;
u32 merged_value;
u32 current_value;
FUNCTION_TRACE ("Ex_write_field_datum_with_update_rule");
/* 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_UINT32_MAX) {
/* Decode the update rule */
switch (obj_desc->common_field.update_rule) {
case UPDATE_PRESERVE:
/*
* Check if update rule needs to be applied (not if mask is all
* ones) The left shift drops the bits we want to ignore.
*/
if ((~mask << (sizeof (mask) * 8 -
obj_desc->common_field.access_bit_width)) != 0) {
/*
* Read the current contents of the byte/word/dword containing
* the field, and merge with the new field value.
*/
status = acpi_ex_read_field_datum (obj_desc, field_datum_byte_offset,
¤t_value);
merged_value |= (current_value & ~mask);
}
break;
case UPDATE_WRITE_AS_ONES:
/* Set positions outside the field to all ones */
merged_value |= ~mask;
break;
case 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.update_rule));
return_ACPI_STATUS (AE_AML_OPERAND_VALUE);
break;
}
}
/* Write the merged value */
status = acpi_ex_write_field_datum (obj_desc, field_datum_byte_offset,
merged_value);
ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD, "Mask %X Datum_offset %X Value %X, Merged_value %X\n",
mask, field_datum_byte_offset, field_value, merged_value));
return_ACPI_STATUS (status);
}
/*******************************************************************************
*
* FUNCTION: Acpi_ex_insert_into_field
*
* PARAMETERS: *Obj_desc - Field to be set
* Buffer - Value to store
*
* RETURN: Status
*
* DESCRIPTION: Store the value into the given field
*
******************************************************************************/
acpi_status
acpi_ex_insert_into_field (
acpi_operand_object *obj_desc,
void *buffer,
u32 buffer_length)
{
acpi_status status;
u32 field_datum_byte_offset;
u32 datum_offset;
u32 mask;
u32 merged_datum;
u32 previous_raw_datum;
u32 this_raw_datum;
u32 byte_field_length;
u32 datum_count;
FUNCTION_TRACE ("Ex_insert_into_field");
/*
* Incoming buffer must be at least as long as the field, we do not
* allow "partial" field writes. We do not care if the buffer is
* larger than the field, this typically happens when an integer is
* written to a field that is actually smaller than an integer.
*/
byte_field_length = ROUND_BITS_UP_TO_BYTES (obj_desc->common_field.bit_length);
if (buffer_length < byte_field_length) {
ACPI_DEBUG_PRINT ((ACPI_DB_INFO, "Buffer length %X too small for field %X\n",
buffer_length, byte_field_length));
/* TBD: Need a better error code */
return_ACPI_STATUS (AE_BUFFER_OVERFLOW);
}
/* Convert byte count to datum count, round up if necessary */
datum_count = ROUND_UP_TO (byte_field_length, obj_desc->common_field.access_byte_width);
ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
"Byte_len=%x, Datum_len=%x, Bit_gran=%x, Byte_gran=%x\n",
byte_field_length, datum_count, obj_desc->common_field.access_bit_width,
obj_desc->common_field.access_byte_width));
/*
* 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,
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 = 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.access_flags & AFIELD_SINGLE_DATUM) &&
obj_desc->common_field.end_field_valid_bits) {
/* There are bits above the field, mask them off also */
mask &= 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_field_datum_with_update_rule (obj_desc, mask, merged_datum,
field_datum_byte_offset);
if (ACPI_FAILURE (status)) {
return_ACPI_STATUS (status);
}
/* If the entire field fits within one datum, we are done. */
if ((datum_count == 1) &&
(obj_desc->common_field.access_flags & AFIELD_SINGLE_DATUM)) {
return_ACPI_STATUS (AE_OK);
}
/*
* Part2:
* Write the aligned data.
*
* We don't need to worry about the update rule for these data, because
* all of the bits in each datum are part of the field.
*
* The last datum must be special cased because it might contain bits
* that are not part of the field -- therefore the "update rule" must be
* applied in Part3 below.
*/
while (datum_offset < datum_count) {
datum_offset++;
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,
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.
*/
if (datum_offset == datum_count) {
/*
* 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
*/
if (obj_desc->common_field.end_field_valid_bits) {
/*
* Part3:
* This is the last datum and the field does not end on a datum boundary.
* Build the partial datum and write with the update rule.
*
* Mask off the unused bits above (after) the end-of-field
*/
mask = MASK_BITS_ABOVE (obj_desc->common_field.end_field_valid_bits);
merged_datum &= mask;
/* Write the last datum with the update rule */
status = acpi_ex_write_field_datum_with_update_rule (obj_desc, mask,
merged_datum, field_datum_byte_offset);
if (ACPI_FAILURE (status)) {
return_ACPI_STATUS (status);
}
}
}
else {
/* Normal case -- write the completed datum */
status = acpi_ex_write_field_datum (obj_desc,
field_datum_byte_offset, merged_datum);
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);
}
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