path: root/drivers/acpi/tables/tbutils.c

/******************************************************************************
 *
 * Module Name: tbutils - Table manipulation 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/actables.h>

#define _COMPONENT          ACPI_TABLES
ACPI_MODULE_NAME("tbutils")

/* Local prototypes */
#ifdef ACPI_OBSOLETE_FUNCTIONS
acpi_status
acpi_tb_handle_to_object(u16 table_id, struct acpi_table_desc **table_desc);
#endif

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_is_table_installed
 *
 * PARAMETERS:  new_table_desc      - Descriptor for new table being installed
 *
 * RETURN:      Status - AE_ALREADY_EXISTS if the table is already installed
 *
 * DESCRIPTION: Determine if an ACPI table is already installed
 *
 * MUTEX:       Table data structures should be locked
 *
 ******************************************************************************/

acpi_status acpi_tb_is_table_installed(struct acpi_table_desc *new_table_desc)
{
	struct acpi_table_desc *table_desc;

	ACPI_FUNCTION_TRACE("tb_is_table_installed");

	/* Get the list descriptor and first table descriptor */

	table_desc = acpi_gbl_table_lists[new_table_desc->type].next;

	/* Examine all installed tables of this type */

	while (table_desc) {
		/*
		 * If the table lengths match, perform a full bytewise compare. This
		 * means that we will allow tables with duplicate oem_table_id(s), as
		 * long as the tables are different in some way.
		 *
		 * Checking if the table has been loaded into the namespace means that
		 * we don't check for duplicate tables during the initial installation
		 * of tables within the RSDT/XSDT.
		 */
		if ((table_desc->loaded_into_namespace) &&
		    (table_desc->pointer->length ==
		     new_table_desc->pointer->length)
		    &&
		    (!ACPI_MEMCMP
		     (table_desc->pointer, new_table_desc->pointer,
		      new_table_desc->pointer->length))) {

			/* Match: this table is already installed */

			ACPI_DEBUG_PRINT((ACPI_DB_TABLES,
					  "Table [%4.4s] already installed: Rev %X oem_table_id [%8.8s]\n",
					  new_table_desc->pointer->signature,
					  new_table_desc->pointer->revision,
					  new_table_desc->pointer->
					  oem_table_id));

			new_table_desc->owner_id = table_desc->owner_id;
			new_table_desc->installed_desc = table_desc;

			return_ACPI_STATUS(AE_ALREADY_EXISTS);
		}

		/* Get next table on the list */

		table_desc = table_desc->next;
	}

	return_ACPI_STATUS(AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_validate_table_header
 *
 * PARAMETERS:  table_header        - Logical pointer to the table
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Check an ACPI table header for validity
 *
 * NOTE:  Table pointers are validated as follows:
 *          1) Table pointer must point to valid physical memory
 *          2) Signature must be 4 ASCII chars, even if we don't recognize the
 *             name
 *          3) Table must be readable for length specified in the header
 *          4) Table checksum must be valid (with the exception of the FACS
 *              which has no checksum because it contains variable fields)
 *
 ******************************************************************************/

acpi_status
acpi_tb_validate_table_header(struct acpi_table_header *table_header)
{
	acpi_name signature;

	ACPI_FUNCTION_ENTRY();

	/* Verify that this is a valid address */

	if (!acpi_os_readable(table_header, sizeof(struct acpi_table_header))) {
		ACPI_ERROR((AE_INFO,
			    "Cannot read table header at %p", table_header));

		return (AE_BAD_ADDRESS);
	}

	/* Ensure that the signature is 4 ASCII characters */

	ACPI_MOVE_32_TO_32(&signature, table_header->signature);
	if (!acpi_ut_valid_acpi_name(signature)) {
		ACPI_ERROR((AE_INFO,
			    "Table signature at %p [%p] has invalid characters",
			    table_header, &signature));

		ACPI_WARNING((AE_INFO, "Invalid table signature found: [%4.4s]",
			      ACPI_CAST_PTR(char, &signature)));

		ACPI_DUMP_BUFFER(table_header,
				 sizeof(struct acpi_table_header));
		return (AE_BAD_SIGNATURE);
	}

	/* Validate the table length */

	if (table_header->length < sizeof(struct acpi_table_header)) {
		ACPI_ERROR((AE_INFO,
			    "Invalid length in table header %p name %4.4s",
			    table_header, (char *)&signature));

		ACPI_WARNING((AE_INFO,
			      "Invalid table header length (0x%X) found",
			      (u32) table_header->length));

		ACPI_DUMP_BUFFER(table_header,
				 sizeof(struct acpi_table_header));
		return (AE_BAD_HEADER);
	}

	return (AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_sum_table
 *
 * PARAMETERS:  Buffer              - Buffer to sum
 *              Length              - Size of the buffer
 *
 * RETURN:      8 bit sum of buffer
 *
 * DESCRIPTION: Computes an 8 bit sum of the buffer(length) and returns it.
 *
 ******************************************************************************/

u8 acpi_tb_sum_table(void *buffer, u32 length)
{
	acpi_native_uint i;
	u8 sum = 0;

	if (!buffer || !length) {
		return (0);
	}

	for (i = 0; i < length; i++) {
		sum = (u8) (sum + ((u8 *) buffer)[i]);
	}
	return (sum);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_generate_checksum
 *
 * PARAMETERS:  Table               - Pointer to a valid ACPI table (with a
 *                                    standard ACPI header)
 *
 * RETURN:      8 bit checksum of buffer
 *
 * DESCRIPTION: Computes an 8 bit checksum of the table.
 *
 ******************************************************************************/

u8 acpi_tb_generate_checksum(struct acpi_table_header * table)
{
	u8 checksum;

	/* Sum the entire table as-is */

	checksum = acpi_tb_sum_table(table, table->length);

	/* Subtract off the existing checksum value in the table */

	checksum = (u8) (checksum - table->checksum);

	/* Compute the final checksum */

	checksum = (u8) (0 - checksum);
	return (checksum);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_set_checksum
 *
 * PARAMETERS:  Table               - Pointer to a valid ACPI table (with a
 *                                    standard ACPI header)
 *
 * RETURN:      None. Sets the table checksum field
 *
 * DESCRIPTION: Computes an 8 bit checksum of the table and inserts the
 *              checksum into the table header.
 *
 ******************************************************************************/

void acpi_tb_set_checksum(struct acpi_table_header *table)
{

	table->checksum = acpi_tb_generate_checksum(table);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_verify_table_checksum
 *
 * PARAMETERS:  *table_header           - ACPI table to verify
 *
 * RETURN:      8 bit checksum of table
 *
 * DESCRIPTION: Generates an 8 bit checksum of table and returns and compares
 *              it to the existing checksum value.
 *
 ******************************************************************************/

acpi_status
acpi_tb_verify_table_checksum(struct acpi_table_header *table_header)
{
	u8 checksum;

	ACPI_FUNCTION_TRACE("tb_verify_table_checksum");

	/* Compute the checksum on the table */

	checksum = acpi_tb_generate_checksum(table_header);

	/* Checksum ok? */

	if (checksum == table_header->checksum) {
		return_ACPI_STATUS(AE_OK);
	}

	ACPI_WARNING((AE_INFO,
		      "Incorrect checksum in table [%4.4s] - is %2.2X, should be %2.2X",
		      table_header->signature, table_header->checksum,
		      checksum));

	return_ACPI_STATUS(AE_BAD_CHECKSUM);
}

#ifdef ACPI_OBSOLETE_FUNCTIONS
/*******************************************************************************
 *
 * FUNCTION:    acpi_tb_handle_to_object
 *
 * PARAMETERS:  table_id            - Id for which the function is searching
 *              table_desc          - Pointer to return the matching table
 *                                      descriptor.
 *
 * RETURN:      Search the tables to find one with a matching table_id and
 *              return a pointer to that table descriptor.
 *
 ******************************************************************************/

acpi_status
acpi_tb_handle_to_object(u16 table_id,
			 struct acpi_table_desc **return_table_desc)
{
	u32 i;
	struct acpi_table_desc *table_desc;

	ACPI_FUNCTION_NAME("tb_handle_to_object");

	for (i = 0; i < ACPI_TABLE_MAX; i++) {
		table_desc = acpi_gbl_table_lists[i].next;
		while (table_desc) {
			if (table_desc->table_id == table_id) {
				*return_table_desc = table_desc;
				return (AE_OK);
			}

			table_desc = table_desc->next;
		}
	}

	ACPI_ERROR((AE_INFO, "table_id=%X does not exist", table_id));
	return (AE_BAD_PARAMETER);
}
#endif