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  1. /*
  2.  * Copyright (C) 2005 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. #include <arch/acpi/acpi.h>
  30. #include <arch/bios/bios.h>
  31.  
  32. #define RSDP_SIGNATURE      "RSD PTR "
  33. #define RSDP_REVISION_OFFS  15
  34.  
  35. struct acpi_rsdp *acpi_rsdp = NULL;
  36.  
  37. int rsdp_check(__u8 *rsdp) {
  38.     struct acpi_rsdp *r = (struct acpi_rsdp *) rsdp;
  39.     __u8 sum = 0;
  40.     int i;
  41.    
  42.     for (i=0; i<20; i++)
  43.         sum += rsdp[i];
  44.        
  45.     if (sum)   
  46.         return 0; /* bad checksum */
  47.  
  48.     if (r->revision == 0)
  49.         return 1; /* ACPI 1.0 */
  50.        
  51.     for (; i<r->length; i++)
  52.         sum += rsdp[i];
  53.        
  54.     return !sum;
  55.    
  56. }
  57.  
  58. void acpi_init(void)
  59. {
  60.         __u8 *addr[2] = { NULL, (__u8 *) 0xe0000 };
  61.         int i, j, length[2] = { 1024, 128*1024 };
  62.     __u64 *sig = (__u64 *) RSDP_SIGNATURE;
  63.  
  64.         /*
  65.      * Find Root System Description Pointer
  66.          * 1. search first 1K of EBDA
  67.          * 2. search 128K starting at 0xe0000
  68.          */
  69.  
  70.     addr[0] = (__u8 *) ebda;
  71.     for (i = (ebda ? 0 : 1); i < 2; i++) {
  72.                 for (j = 0; j < length[i]; j += 16) {
  73.                         if (*((__u64 *) &addr[i][j]) == *sig && rsdp_check(&addr[i][j])) {
  74.                                 acpi_rsdp = (struct acpi_rsdp *) &addr[i][j];
  75.                                 goto rsdp_found;
  76.                         }
  77.                 }
  78.         }
  79.  
  80.         return;
  81.  
  82. rsdp_found:
  83.         printf("%L: ACPI Root System Description Pointer\n", acpi_rsdp);       
  84. }
  85.