exprep.c

LINUX 2.6.17.4的源码

/******************************************************************************
 *
 * Module Name: exprep - ACPI AML (p-code) execution - field prep utilities
 *
 *****************************************************************************/

/*
 * Copyright (C) 2000 - 2006, 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/acnamesp.h>

#define _COMPONENT          ACPI_EXECUTER
ACPI_MODULE_NAME("exprep")

/* Local prototypes */
static u32
acpi_ex_decode_field_access(union acpi_operand_object *obj_desc,
			    u8 field_flags, u32 * return_byte_alignment);

#ifdef ACPI_UNDER_DEVELOPMENT

static u32
acpi_ex_generate_access(u32 field_bit_offset,
			u32 field_bit_length, u32 region_length);

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_generate_access
 *
 * PARAMETERS:  field_bit_offset    - Start of field within parent region/buffer
 *              field_bit_length    - Length of field in bits
 *              region_length       - Length of parent in bytes
 *
 * RETURN:      Field granularity (8, 16, 32 or 64) and
 *              byte_alignment (1, 2, 3, or 4)
 *
 * DESCRIPTION: Generate an optimal access width for fields defined with the
 *              any_acc keyword.
 *
 * NOTE: Need to have the region_length in order to check for boundary
 *       conditions (end-of-region).  However, the region_length is a deferred
 *       operation.  Therefore, to complete this implementation, the generation
 *       of this access width must be deferred until the region length has
 *       been evaluated.
 *
 ******************************************************************************/

static u32
acpi_ex_generate_access(u32 field_bit_offset,
			u32 field_bit_length, u32 region_length)
{
	u32 field_byte_length;
	u32 field_byte_offset;
	u32 field_byte_end_offset;
	u32 access_byte_width;
	u32 field_start_offset;
	u32 field_end_offset;
	u32 minimum_access_width = 0xFFFFFFFF;
	u32 minimum_accesses = 0xFFFFFFFF;
	u32 accesses;

	ACPI_FUNCTION_TRACE("ex_generate_access");

	/* Round Field start offset and length to "minimal" byte boundaries */

	field_byte_offset = ACPI_DIV_8(ACPI_ROUND_DOWN(field_bit_offset, 8));
	field_byte_end_offset = ACPI_DIV_8(ACPI_ROUND_UP(field_bit_length +
							 field_bit_offset, 8));
	field_byte_length = field_byte_end_offset - field_byte_offset;

	ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
			  "Bit length %d, Bit offset %d\n",
			  field_bit_length, field_bit_offset));

	ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
			  "Byte Length %d, Byte Offset %d, End Offset %d\n",
			  field_byte_length, field_byte_offset,
			  field_byte_end_offset));

	/*
	 * Iterative search for the maximum access width that is both aligned
	 * and does not go beyond the end of the region
	 *
	 * Start at byte_acc and work upwards to qword_acc max. (1,2,4,8 bytes)
	 */
	for (access_byte_width = 1; access_byte_width <= 8;
	     access_byte_width <<= 1) {
		/*
		 * 1) Round end offset up to next access boundary and make sure that
		 *    this does not go beyond the end of the parent region.
		 * 2) When the Access width is greater than the field_byte_length, we
		 *    are done. (This does not optimize for the perfectly aligned
		 *    case yet).
		 */
		if (ACPI_ROUND_UP(field_byte_end_offset, access_byte_width) <=
		    region_length) {
			field_start_offset =
			    ACPI_ROUND_DOWN(field_byte_offset,
					    access_byte_width) /
			    access_byte_width;

			field_end_offset =
			    ACPI_ROUND_UP((field_byte_length +
					   field_byte_offset),
					  access_byte_width) /
			    access_byte_width;

			accesses = field_end_offset - field_start_offset;

			ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
					  "access_width %d end is within region\n",
					  access_byte_width));

			ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
					  "Field Start %d, Field End %d -- requires %d accesses\n",
					  field_start_offset, field_end_offset,
					  accesses));

			/* Single access is optimal */

			if (accesses <= 1) {
				ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
						  "Entire field can be accessed with one operation of size %d\n",
						  access_byte_width));
				return_VALUE(access_byte_width);
			}

			/*
			 * Fits in the region, but requires more than one read/write.
			 * try the next wider access on next iteration
			 */
			if (accesses < minimum_accesses) {
				minimum_accesses = accesses;
				minimum_access_width = access_byte_width;
			}
		} else {
			ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
					  "access_width %d end is NOT within region\n",
					  access_byte_width));
			if (access_byte_width == 1) {
				ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
						  "Field goes beyond end-of-region!\n"));

				/* Field does not fit in the region at all */

				return_VALUE(0);
			}

			/*
			 * This width goes beyond the end-of-region, back off to
			 * previous access
			 */
			ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
					  "Backing off to previous optimal access width of %d\n",
					  minimum_access_width));
			return_VALUE(minimum_access_width);
		}
	}

	/*
	 * Could not read/write field with one operation,
	 * just use max access width
	 */
	ACPI_DEBUG_PRINT((ACPI_DB_BFIELD,
			  "Cannot access field in one operation, using width 8\n"));
	return_VALUE(8);
}
#endif				/* ACPI_UNDER_DEVELOPMENT */

/*******************************************************************************
 *
 * FUNCTION:    acpi_ex_decode_field_access
 *
 * PARAMETERS:  obj_desc            - Field object
 *              field_flags         - Encoded fieldflags (contains access bits)
 *              return_byte_alignment - Where the byte alignment is returned
 *
 * RETURN:      Field granularity (8, 16, 32 or 64) and
 *              byte_alignment (1, 2, 3, or 4)
 *
 * DESCRIPTION: Decode the access_type bits of a field definition.
 *
 ******************************************************************************/

static u32
acpi_ex_decode_field_access(union acpi_operand_object *obj_desc,
			    u8 field_flags, u32 * return_byte_alignment)
{
	u32 access;
	u32 byte_alignment;
	u32 bit_length;

	ACPI_FUNCTION_TRACE("ex_decode_field_access");

	access = (field_flags & AML_FIELD_ACCESS_TYPE_MASK);

	switch (access) {
	case AML_FIELD_ACCESS_ANY:

#ifdef ACPI_UNDER_DEVELOPMENT
		byte_alignment =
		    acpi_ex_generate_access(obj_desc->common_field.
					    start_field_bit_offset,
					    obj_desc->common_field.bit_length,
					    0xFFFFFFFF
					    /* Temp until we pass region_length as parameter */
					    );
		bit_length = byte_alignment * 8;
#endif

		byte_alignment = 1;
		bit_length = 8;
		break;

	case AML_FIELD_ACCESS_BYTE:
	case AML_FIELD_ACCESS_BUFFER:	/* ACPI 2.0 (SMBus Buffer) */
		byte_alignment = 1;
		bit_length = 8;
		break;

	case AML_FIELD_ACCESS_WORD:
		byte_alignment = 2;
		bit_length = 16;
		break;

	case AML_FIELD_ACCESS_DWORD:
		byte_alignment = 4;
		bit_length = 32;
		break;

	case AML_FIELD_ACCESS_QWORD:	/* ACPI 2.0 */
		byte_alignment = 8;
		bit_length = 64;
		break;

	default:
		/* Invalid field access type */

		ACPI_ERROR((AE_INFO, "Unknown field access type %X", access));
		return_UINT32(0);
	}

	if (ACPI_GET_OBJECT_TYPE(obj_desc) == ACPI_TYPE_BUFFER_FIELD) {