src/system/kernel/arch/x86/32/bios.cpp

   1 /*
   2  * Copyright 2004-2006, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
   3  * Distributed under the terms of the MIT License.
   4  */
   5
   6
   7 #include <KernelExport.h>
   8 #include <vm/vm_types.h>
   9
  10 #include <arch/x86/bios.h>
  11
  12
  13 //#define TRACE_BIOS
  14 #ifdef TRACE_BIOS
  15 #       define TRACE(x) dprintf x
  16 #else
  17 #       define TRACE(x) ;
  18 #endif
  19
  20
  21 struct smbios {
  22         uint32          anchor_string;
  23         uint8           entry_point_checksum;
  24         uint8           entry_point_length;
  25         struct {
  26                 uint8   major;
  27                 uint8   minor;
  28         } version;
  29         uint16          maximum_size;
  30         uint8           formatted_area[5];
  31
  32         // this part is the legacy DMI compatible structure
  33         uint8           dmi_anchor_string[5];
  34         uint8           intermediate_checksum;
  35         uint16          structure_table_size;
  36         uint32          structure_table;
  37         uint16          num_structures;
  38         uint8           bcd_revision;
  39 } _PACKED;
  40
  41 struct bios32 {
  42         uint32          anchor_string;
  43         uint32          service_directory;
  44         uint8           revision;
  45         uint8           size;   // in "paragraph" (16 byte) units
  46         uint8           checksum;
  47         uint8           _reserved[5];
  48 };
  49
  50 enum {
  51         BIOS32  = '_23_',
  52         SMBIOS  = '_MS_',
  53         DMI             = '_IMD',
  54 };
  55
  56
  57 addr_t gBiosBase;
  58 static addr_t sBios32ServiceDirectory;
  59
  60
  61 static bool
  62 check_checksum(addr_t base, size_t length)
  63 {
  64         uint8 *bytes = (uint8 *)base;
  65         uint8 sum = 0;
  66
  67         for (uint32 i = 0; i < length; i++)
  68                 sum += bytes[i];
  69
  70         return sum == 0;
  71 }
  72
  73
  74 //      #pragma mark -
  75 //      public functions
  76
  77
  78 /**     This function fills the provided bios32_service structure with
  79  *      the values that identify BIOS service.
  80  *      Returns B_OK on successful completion, otherwise B_ERROR if
  81  *      the BIOS32 service directory is not available, or B_BAD_VALUE
  82  *      in case the identifier is not known or present.
  83  */
  84
  85 extern "C" status_t
  86 get_bios32_service(uint32 identifier, struct bios32_service *service)
  87 {
  88         TRACE(("get_bios32_service(identifier = %#lx)\n", identifier));
  89
  90         if (sBios32ServiceDirectory == 0)
  91                 return B_ERROR;
  92
  93         uint32 eax = 0, ebx = 0, ecx = 0, edx = 0;
  94
  95         asm("movl       %4, %%eax;              "       // set service parameters
  96                 "xorl   %%ebx, %%ebx;   "
  97                 "movl   %5, %%ecx;              "
  98                 "pushl  %%cs;                   "       // emulate far call by register
  99                 "call   *%%ecx;                 "
 100                 "movl   %%eax, %0;              "       // save return values
 101                 "movl   %%ebx, %1;              "
 102                 "movl   %%ecx, %2;              "
 103                 "movl   %%edx, %3;              "
 104                 : "=m" (eax), "=m" (ebx), "=m" (ecx), "=m" (edx)
 105                 : "m" (identifier), "m" (sBios32ServiceDirectory)
 106                 : "eax", "ebx", "ecx", "edx", "memory");
 107
 108         if ((eax & 0xff) != 0)
 109                 return B_BAD_VALUE;
 110
 111         service->base = ebx;
 112         service->size = ecx;
 113         service->offset = edx;
 114
 115         return B_OK;
 116 }
 117
 118
 119 extern "C" status_t
 120 bios_init(void)
 121 {
 122         // map BIOS area 0xe0000 - 0xfffff
 123         area_id biosArea = map_physical_memory("pc bios", 0xe0000, 0x20000,
 124                 B_ANY_KERNEL_ADDRESS | B_MTR_WB,
 125                 B_KERNEL_READ_AREA | B_KERNEL_WRITE_AREA, (void **)&gBiosBase);
 126         if (biosArea < 0)
 127                 return biosArea;
 128
 129         TRACE(("PC BIOS mapped to %p\n", (void *)gBiosBase));
 130
 131         // ToDo: add driver settings support to disable the services below
 132
 133         // search for available BIOS services
 134
 135         addr_t base = gBiosBase;
 136         addr_t end = base + 0x20000;
 137
 138         while (base < end) {
 139                 switch (*(uint32 *)base) {
 140                         case BIOS32:
 141                                 if (check_checksum(base, sizeof(struct bios32))) {
 142                                         struct bios32 *bios32 = (struct bios32 *)base;
 143
 144                                         TRACE(("bios32 revision %d\n", bios32->revision));
 145                                         TRACE(("bios32 service directory at: %lx\n", bios32->service_directory));
 146
 147                                         if (bios32->service_directory >= 0xe0000
 148                                                 && bios32->service_directory <= 0xfffff)
 149                                                 sBios32ServiceDirectory = gBiosBase - 0xe0000 + bios32->service_directory;
 150                                 }
 151                                 break;
 152                         case SMBIOS:
 153                                 // SMBIOS contains the legacy DMI structure, so we have to
 154                                 // make sure it won't be found
 155                                 base += 16;
 156                                 TRACE(("probably found SMBIOS structure.\n"));
 157                                 break;
 158                         case DMI:
 159                                 TRACE(("probably found DMI legacy structure.\n"));
 160                                 break;
 161                 }
 162
 163                 // get on to next "paragraph"
 164                 base += 16;
 165         }
 166
 167         return B_OK;
 168 }
 169