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

 *

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

 *

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

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

 *

 * 1. Copyright Notice

 *

 * Some or all of this work - Copyright (c) 1999 - 2011, Intel Corp.

 * All rights reserved.

 *

 * 2. License

 *

 * 2.1. This is your license from Intel Corp. under its intellectual property

 * rights.  You may have additional license terms from the party that provided

 * you this software, covering your right to use that party's intellectual

 * property rights.

 *

 * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a

 * copy of the source code appearing in this file ("Covered Code") an

 * irrevocable, perpetual, worldwide license under Intel's copyrights in the

 * base code distributed originally by Intel ("Original Intel Code") to copy,

 * make derivatives, distribute, use and display any portion of the Covered

 * Code in any form, with the right to sublicense such rights; and

 *

 * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent

 * license (with the right to sublicense), under only those claims of Intel

 * patents that are infringed by the Original Intel Code, to make, use, sell,

 * offer to sell, and import the Covered Code and derivative works thereof

 * solely to the minimum extent necessary to exercise the above copyright

 * license, and in no event shall the patent license extend to any additions

 * to or modifications of the Original Intel Code.  No other license or right

 * is granted directly or by implication, estoppel or otherwise;

 *

 * The above copyright and patent license is granted only if the following

 * conditions are met:

 *

 * 3. Conditions

 *

 * 3.1. Redistribution of Source with Rights to Further Distribute Source.

 * Redistribution of source code of any substantial portion of the Covered

 * Code or modification with rights to further distribute source must include

 * the above Copyright Notice, the above License, this list of Conditions,

 * and the following Disclaimer and Export Compliance provision.  In addition,

 * Licensee must cause all Covered Code to which Licensee contributes to

 * contain a file documenting the changes Licensee made to create that Covered

 * Code and the date of any change.  Licensee must include in that file the

 * documentation of any changes made by any predecessor Licensee.  Licensee

 * must include a prominent statement that the modification is derived,

 * directly or indirectly, from Original Intel Code.

 *

 * 3.2. Redistribution of Source with no Rights to Further Distribute Source.

 * Redistribution of source code of any substantial portion of the Covered

 * Code or modification without rights to further distribute source must

 * include the following Disclaimer and Export Compliance provision in the

 * documentation and/or other materials provided with distribution.  In

 * addition, Licensee may not authorize further sublicense of source of any

 * portion of the Covered Code, and must include terms to the effect that the

 * license from Licensee to its licensee is limited to the intellectual

 * property embodied in the software Licensee provides to its licensee, and

 * not to intellectual property embodied in modifications its licensee may

 * make.

 *

 * 3.3. Redistribution of Executable. Redistribution in executable form of any

 * substantial portion of the Covered Code or modification must reproduce the

 * above Copyright Notice, and the following Disclaimer and Export Compliance

 * provision in the documentation and/or other materials provided with the

 * distribution.

 *

 * 3.4. Intel retains all right, title, and interest in and to the Original

 * Intel Code.

 *

 * 3.5. Neither the name Intel nor any other trademark owned or controlled by

 * Intel shall be used in advertising or otherwise to promote the sale, use or

 * other dealings in products derived from or relating to the Covered Code

 * without prior written authorization from Intel.

 *

 * 4. Disclaimer and Export Compliance

 *

 * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED

 * HERE.  ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE

 * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT,  ASSISTANCE,

 * INSTALLATION, TRAINING OR OTHER SERVICES.  INTEL WILL NOT PROVIDE ANY

 * UPDATES, ENHANCEMENTS OR EXTENSIONS.  INTEL SPECIFICALLY DISCLAIMS ANY

 * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A

 * PARTICULAR PURPOSE.

 *

 * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES

 * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR

 * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,

 * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY

 * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL

 * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.  THESE LIMITATIONS

 * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY

 * LIMITED REMEDY.

 *

 * 4.3. Licensee shall not export, either directly or indirectly, any of this

 * software or system incorporating such software without first obtaining any

 * required license or other approval from the U. S. Department of Commerce or

 * any other agency or department of the United States Government.  In the

 * event Licensee exports any such software from the United States or

 * re-exports any such software from a foreign destination, Licensee shall

 * ensure that the distribution and export/re-export of the software is in

 * compliance with all laws, regulations, orders, or other restrictions of the

 * U.S. Export Administration Regulations. Licensee agrees that neither it nor

 * any of its subsidiaries will export/re-export any technical data, process,

 * software, or service, directly or indirectly, to any country for which the

 * United States government or any agency thereof requires an export license,

 * other governmental approval, or letter of assurance, without first obtaining

 * such license, approval or letter.

 *

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

#define __TBXFROOT_C__

#include "acpi.h"

#include "accommon.h"

#include "actables.h"

#define _COMPONENT          ACPI_TABLES

        ACPI_MODULE_NAME    ("tbxfroot")

/* Local prototypes */

static UINT8 *

AcpiTbScanMemoryForRsdp (

    UINT8                   *StartAddress,

    UINT32                  Length);

static ACPI_STATUS

AcpiTbValidateRsdp (

    ACPI_TABLE_RSDP         *Rsdp);

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

 *

 * FUNCTION:    AcpiTbValidateRsdp

 *

 * PARAMETERS:  Rsdp                - Pointer to unvalidated RSDP

 *

 * RETURN:      Status

 *

 * DESCRIPTION: Validate the RSDP (ptr)

 *

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

static ACPI_STATUS

AcpiTbValidateRsdp (

    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 (AcpiTbChecksum ((UINT8 *) Rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0)

    {

        return (AE_BAD_CHECKSUM);

    }

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

    if ((Rsdp->Revision >= 2) &&

        (AcpiTbChecksum ((UINT8 *) Rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0))

    {

        return (AE_BAD_CHECKSUM);

    }

    return (AE_OK);

}

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

 *

 * FUNCTION:    AcpiFindRootPointer

 *

 * PARAMETERS:  TableAddress            - Where the table pointer is returned

 *

 * RETURN:      Status, RSDP physical address

 *

 * DESCRIPTION: Search lower 1Mbyte 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 1K 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

AcpiFindRootPointer (

    ACPI_SIZE               *TableAddress)

{

    UINT8                   *TablePtr;

    UINT8                   *MemRover;

    UINT32                  PhysicalAddress;

    ACPI_FUNCTION_TRACE (AcpiFindRootPointer);

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

    TablePtr = AcpiOsMapMemory (

                (ACPI_PHYSICAL_ADDRESS) ACPI_EBDA_PTR_LOCATION,

                ACPI_EBDA_PTR_LENGTH);

    if (!TablePtr)

    {

        ACPI_ERROR ((AE_INFO,

            "Could not map memory at 0x%8.8X for length %u",

            ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));

        return_ACPI_STATUS (AE_NO_MEMORY);

    }

    ACPI_MOVE_16_TO_32 (&PhysicalAddress, TablePtr);

    /* Convert segment part to physical address */

    PhysicalAddress <<= 4;

    AcpiOsUnmapMemory (TablePtr, ACPI_EBDA_PTR_LENGTH);

    /* EBDA present? */

    if (PhysicalAddress > 0x400)

    {

        /*

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

         *     minimum of 1K length)

         */

        TablePtr = AcpiOsMapMemory (

                    (ACPI_PHYSICAL_ADDRESS) PhysicalAddress,

                    ACPI_EBDA_WINDOW_SIZE);

        if (!TablePtr)

        {

            ACPI_ERROR ((AE_INFO,

                "Could not map memory at 0x%8.8X for length %u",

                PhysicalAddress, ACPI_EBDA_WINDOW_SIZE));

            return_ACPI_STATUS (AE_NO_MEMORY);

        }

        MemRover = AcpiTbScanMemoryForRsdp (TablePtr, ACPI_EBDA_WINDOW_SIZE);

        AcpiOsUnmapMemory (TablePtr, ACPI_EBDA_WINDOW_SIZE);

        if (MemRover)

        {

            /* Return the physical address */

            PhysicalAddress += (UINT32) ACPI_PTR_DIFF (MemRover, TablePtr);

            *TableAddress = PhysicalAddress;

            return_ACPI_STATUS (AE_OK);

        }

    }

    /*

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

     */

    TablePtr = AcpiOsMapMemory (

                (ACPI_PHYSICAL_ADDRESS) ACPI_HI_RSDP_WINDOW_BASE,

                ACPI_HI_RSDP_WINDOW_SIZE);

    if (!TablePtr)

    {

        ACPI_ERROR ((AE_INFO,

            "Could not map memory at 0x%8.8X for length %u",

            ACPI_HI_RSDP_WINDOW_BASE, ACPI_HI_RSDP_WINDOW_SIZE));

        return_ACPI_STATUS (AE_NO_MEMORY);

    }

    MemRover = AcpiTbScanMemoryForRsdp (TablePtr, ACPI_HI_RSDP_WINDOW_SIZE);

    AcpiOsUnmapMemory (TablePtr, ACPI_HI_RSDP_WINDOW_SIZE);

    if (MemRover)

    {

        /* Return the physical address */

        PhysicalAddress = (UINT32)

            (ACPI_HI_RSDP_WINDOW_BASE + ACPI_PTR_DIFF (MemRover, TablePtr));

        *TableAddress = PhysicalAddress;

        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 (AcpiFindRootPointer)

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

 *

 * FUNCTION:    AcpiTbScanMemoryForRsdp

 *

 * PARAMETERS:  StartAddress        - 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 UINT8 *

AcpiTbScanMemoryForRsdp (

    UINT8                   *StartAddress,

    UINT32                  Length)

{

    ACPI_STATUS             Status;

    UINT8                   *MemRover;

    UINT8                   *EndAddress;

    ACPI_FUNCTION_TRACE (TbScanMemoryForRsdp);

    EndAddress = StartAddress + Length;

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

    for (MemRover = StartAddress; MemRover < EndAddress;

         MemRover += ACPI_RSDP_SCAN_STEP)

    {

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

        Status = AcpiTbValidateRsdp (ACPI_CAST_PTR (ACPI_TABLE_RSDP, MemRover));

        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", MemRover));

            return_PTR (MemRover);

        }

        /* 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",

        StartAddress));

    return_PTR (NULL);

}