exprep.c

h内核

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

/*
 * Copyright (C) 2000 - 2005, 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")


#ifdef ACPI_UNDER_DEVELOPMENT
/*******************************************************************************
 *
 * 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"));
				return_VALUE (0);     /* Field does not fit in the region at all */
			}

			/* 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:  Access          - Encoded field access bits
 *              Length          - Field length.
 *
 * 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 param */);
		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_DEBUG_PRINT ((ACPI_DB_ERROR,
			"Unknown field access type %X\n",
			access));
		return_VALUE (0);
	}

	if (ACPI_GET_OBJECT_TYPE (obj_desc) == ACPI_TYPE_BUFFER_FIELD) {
		/*
		 * buffer_field access can be on any byte boundary, so the
		 * byte_alignment is always 1 byte -- regardless of any byte_alignment
		 * implied by the field access type.
		 */
		byte_alignment = 1;
	}

	*return_byte_alignment = byte_alignment;