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29 jermar 1
/*
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 * Copyright (C) 2005 Jakub Jermar
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#include <arch/acpi/acpi.h>
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#include <arch/bios/bios.h>
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#define RSDP_SIGNATURE      "RSD PTR "
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#define RSDP_REVISION_OFFS  15
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struct acpi_rsdp *acpi_rsdp = NULL;
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int rsdp_check(__u8 *rsdp) {
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    struct acpi_rsdp *r = (struct acpi_rsdp *) rsdp;
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    __u8 sum = 0;
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    int i;
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    for (i=0; i<20; i++)
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        sum += rsdp[i];
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    if (sum)   
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        return 0; /* bad checksum */
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    if (r->revision == 0)
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        return 1; /* ACPI 1.0 */
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    for (; i<r->length; i++)
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        sum += rsdp[i];
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    return !sum;
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}
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void acpi_init(void)
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{
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        __u8 *addr[2] = { NULL, (__u8 *) 0xe0000 };
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        int i, j, length[2] = { 1024, 128*1024 };
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    __u64 *sig = (__u64 *) RSDP_SIGNATURE;
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        /*
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     * Find Root System Description Pointer
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         * 1. search first 1K of EBDA
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         * 2. search 128K starting at 0xe0000
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         */
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    addr[0] = (__u8 *) ebda;
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    for (i = (ebda ? 0 : 1); i < 2; i++) {
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                for (j = 0; j < length[i]; j += 16) {
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                        if (*((__u64 *) &addr[i][j]) == *sig && rsdp_check(&addr[i][j])) {
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                                acpi_rsdp = (struct acpi_rsdp *) &addr[i][j];
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                                goto rsdp_found;
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                        }
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                }
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        }
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        return;
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rsdp_found:
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        printf("%L: ACPI Root System Description Pointer\n", acpi_rsdp);       
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}