/******************************************************************************
*
* Module Name: exfldio - Aml Field I/O
*
*****************************************************************************/
/*
* Copyright (C) 2000 - 2008, 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,
acpi_integer * value, u32 read_write);
static u8
acpi_ex_register_overflow(union acpi_operand_object *obj_desc,
acpi_integer 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;
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 %X (%s)",
rgn_desc->common.type,
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);
}
}
/* 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 address space, it has a non-linear address space
* and the request cannot be directly validated
*/
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. 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 (%d bytes) too large for region [%4.4s] (length %X)",
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 %X+%X+%X is beyond end of region [%4.4s] (length %X)",
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;
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, 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(%X) 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(%X) 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,
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)
*
******************************************************************************/
static 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;
/* 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,
(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);
}
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(acpi_integer));
} 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(acpi_integer));
}
break;
default:
ACPI_ERROR((AE_INFO, "Wrong object type in field I/O %X",
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 %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 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,
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,
¤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: %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;
acpi_integer raw_datum;
acpi_integer merged_datum;
u32 field_offset = 0;
u32 buffer_offset = 0;
u32 buffer_tail_bits;
u32 datum_count;
u32 field_datum_count;
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 %X (bits) is too large for buffer (%X)",
obj_desc->common_field.bit_length, buffer_length));
return_ACPI_STATUS(AE_BUFFER_OVERFLOW);
}
ACPI_MEMSET(buffer, 0, buffer_length);
/* Compute the number of datums (access width data items) */
datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length,
obj_desc->common_field.access_bit_width);
field_datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length +
obj_desc->common_field.
start_field_bit_offset,
obj_desc->common_field.
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 ((obj_desc->common_field.access_bit_width -
obj_desc->common_field.start_field_bit_offset) <
ACPI_INTEGER_BIT_SIZE) {
merged_datum |=
raw_datum << (obj_desc->common_field.
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 %
obj_desc->common_field.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)
{
acpi_status status;
acpi_integer mask;
acpi_integer width_mask;
acpi_integer merged_datum;
acpi_integer raw_datum = 0;
u32 field_offset = 0;
u32 buffer_offset = 0;
u32 buffer_tail_bits;
u32 datum_count;
u32 field_datum_count;
u32 i;
u32 required_length;
void *new_buffer;
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;
}
/*
* Create the bitmasks used for bit insertion.
* Note: This if/else is used to bypass compiler differences with the
* shift operator
*/
if (obj_desc->common_field.access_bit_width == ACPI_INTEGER_BIT_SIZE) {
width_mask = ACPI_INTEGER_MAX;
} else {
width_mask =
ACPI_MASK_BITS_ABOVE(obj_desc->common_field.
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,
obj_desc->common_field.access_bit_width);
field_datum_count = ACPI_ROUND_UP_TO(obj_desc->common_field.bit_length +
obj_desc->common_field.
start_field_bit_offset,
obj_desc->common_field.
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 ((obj_desc->common_field.access_bit_width -
obj_desc->common_field.start_field_bit_offset) <
ACPI_INTEGER_BIT_SIZE) {
merged_datum =
raw_datum >> (obj_desc->common_field.
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) %
obj_desc->common_field.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);
}
