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/******************************************************************************

 *

 * Module Name: tbxfroot - Find the root ACPI table (RSDT)

 *

 *****************************************************************************/

/*

 * Copyright (C) 2000 - 2007, 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("tbxfroot")

/* Local prototypes */

static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length);

static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp);

/*******************************************************************************

 *

 * FUNCTION:    acpi_tb_validate_rsdp

 *

 * PARAMETERS:  Rsdp                - Pointer to unvalidated RSDP

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Validate the RSDP (ptr)

 *

 ******************************************************************************/

static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp)

{

        ACPI_FUNCTION_ENTRY();

        /*

         * The signature and checksum must both be correct

         *

         * Note: Sometimes there exists more than one RSDP in memory; the valid

         * RSDP has a valid checksum, all others have an invalid checksum.

         */

        if (ACPI_STRNCMP((char *)rsdp, ACPI_SIG_RSDP, sizeof(ACPI_SIG_RSDP) - 1)

            != 0) {

                /* Nope, BAD Signature */

                return (AE_BAD_SIGNATURE);

        }

        /* Check the standard checksum */

        if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {

                return (AE_BAD_CHECKSUM);

        }

        /* Check extended checksum if table version >= 2 */

        if ((rsdp->revision >= 2) &&

            (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {

                return (AE_BAD_CHECKSUM);

        }

        return (AE_OK);

}

/*******************************************************************************

 *

 * FUNCTION:    acpi_tb_find_rsdp

 *

 * PARAMETERS:  table_address           - Where the table pointer is returned

 *

 * RETURN:      Status, RSDP physical address

 *

 * DESCRIPTION: Search lower 1_mbyte of memory for the root system descriptor

 *              pointer structure.  If it is found, set *RSDP to point to it.

 *

 * NOTE1:       The RSDP must be either in the first 1_k of the Extended

 *              BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)

 *              Only a 32-bit physical address is necessary.

 *

 * NOTE2:       This function is always available, regardless of the

 *              initialization state of the rest of ACPI.

 *

 ******************************************************************************/

acpi_status acpi_find_root_pointer(acpi_native_uint * table_address)

{

        u8 *table_ptr;

        u8 *mem_rover;

        u32 physical_address;

        ACPI_FUNCTION_TRACE(acpi_find_root_pointer);

        /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */

        table_ptr = acpi_os_map_memory((acpi_physical_address)

                                       ACPI_EBDA_PTR_LOCATION,

                                       ACPI_EBDA_PTR_LENGTH);

        if (!table_ptr) {

                ACPI_ERROR((AE_INFO,

                            "Could not map memory at %8.8X for length %X",

                            ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));

                return_ACPI_STATUS(AE_NO_MEMORY);

        }

        ACPI_MOVE_16_TO_32(&physical_address, table_ptr);

        /* Convert segment part to physical address */

        physical_address <<= 4;

        acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH);

        /* EBDA present? */

        if (physical_address > 0x400) {

                /*

                 * 1b) Search EBDA paragraphs (EBDA is required to be a

                 *     minimum of 1_k length)

                 */

                table_ptr = acpi_os_map_memory((acpi_native_uint)

                                               physical_address,

                                               ACPI_EBDA_WINDOW_SIZE);

                if (!table_ptr) {

                        ACPI_ERROR((AE_INFO,

                                    "Could not map memory at %8.8X for length %X",

                                    physical_address, ACPI_EBDA_WINDOW_SIZE));

                        return_ACPI_STATUS(AE_NO_MEMORY);

                }

                mem_rover =

                    acpi_tb_scan_memory_for_rsdp(table_ptr,

                                                 ACPI_EBDA_WINDOW_SIZE);

                acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE);

                if (mem_rover) {

                        /* Return the physical address */

                        physical_address +=

                            (u32) ACPI_PTR_DIFF(mem_rover, table_ptr);

                        *table_address = physical_address;

                        return_ACPI_STATUS(AE_OK);

                }

        }

        /*

         * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh

         */

        table_ptr = acpi_os_map_memory((acpi_physical_address)

                                       ACPI_HI_RSDP_WINDOW_BASE,

                                       ACPI_HI_RSDP_WINDOW_SIZE);

        if (!table_ptr) {

                ACPI_ERROR((AE_INFO,

                            "Could not map memory at %8.8X for length %X",

                            ACPI_HI_RSDP_WINDOW_BASE,

                            ACPI_HI_RSDP_WINDOW_SIZE));

                return_ACPI_STATUS(AE_NO_MEMORY);

        }

        mem_rover =

            acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);

        acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);

        if (mem_rover) {

                /* Return the physical address */

                physical_address = (u32)

                    (ACPI_HI_RSDP_WINDOW_BASE +

                     ACPI_PTR_DIFF(mem_rover, table_ptr));

                *table_address = physical_address;

                return_ACPI_STATUS(AE_OK);

        }

        /* A valid RSDP was not found */

        ACPI_ERROR((AE_INFO, "A valid RSDP was not found"));

        return_ACPI_STATUS(AE_NOT_FOUND);

}

ACPI_EXPORT_SYMBOL(acpi_find_root_pointer)

/*******************************************************************************

 *

 * FUNCTION:    acpi_tb_scan_memory_for_rsdp

 *

 * PARAMETERS:  start_address       - Starting pointer for search

 *              Length              - Maximum length to search

 *

 * RETURN:      Pointer to the RSDP if found, otherwise NULL.

 *

 * DESCRIPTION: Search a block of memory for the RSDP signature

 *

 ******************************************************************************/

static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length)

{

        acpi_status status;

        u8 *mem_rover;

        u8 *end_address;

        ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp);

        end_address = start_address + length;

        /* Search from given start address for the requested length */

        for (mem_rover = start_address; mem_rover < end_address;

             mem_rover += ACPI_RSDP_SCAN_STEP) {

                /* The RSDP signature and checksum must both be correct */

                status =

                    acpi_tb_validate_rsdp(ACPI_CAST_PTR

                                          (struct acpi_table_rsdp, mem_rover));

                if (ACPI_SUCCESS(status)) {

                        /* Sig and checksum valid, we have found a real RSDP */

                        ACPI_DEBUG_PRINT((ACPI_DB_INFO,

                                          "RSDP located at physical address %p\n",

                                          mem_rover));

                        return_PTR(mem_rover);

                }

                /* No sig match or bad checksum, keep searching */

        }

        /* Searched entire block, no RSDP was found */

        ACPI_DEBUG_PRINT((ACPI_DB_INFO,

                          "Searched entire block from %p, valid RSDP was not found\n",

                          start_address));

        return_PTR(NULL);

}