wimboot/wimboot-2.7.3/src/int13.c

   1 /*
   2  * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  17  * 02110-1301, USA.
  18  */
  19
  20 /**
  21  * @file
  22  *
  23  * INT 13 emulation
  24  *
  25  */
  26
  27 #include <string.h>
  28 #include <stdio.h>
  29 #include "wimboot.h"
  30 #include "int13.h"
  31 #include "vdisk.h"
  32
  33 /** Emulated drive number */
  34 static int vdisk_drive;
  35
  36 /**
  37  * Initialise emulation
  38  *
  39  * @ret drive           Emulated drive number
  40  */
  41 int initialise_int13 ( void ) {
  42
  43         /* Determine drive number */
  44         vdisk_drive = ( 0x80 | INT13_DRIVE_COUNT++ );
  45         DBG ( "Emulating drive %#02x\n", vdisk_drive );
  46
  47         return vdisk_drive;
  48 }
  49
  50 /**
  51  * INT 13, 08 - Get drive parameters
  52  *
  53  * @ret ch              Low bits of maximum cylinder number
  54  * @ret cl (bits 7:6)   High bits of maximum cylinder number
  55  * @ret cl (bits 5:0)   Maximum sector number
  56  * @ret dh              Maximum head number
  57  * @ret dl              Number of drives
  58  * @ret ah              Status code
  59  */
  60 static void int13_get_parameters ( struct bootapp_callback_params *params ) {
  61         unsigned int max_cylinder = ( VDISK_CYLINDERS - 1 );
  62         unsigned int max_head = ( VDISK_HEADS - 1 );
  63         unsigned int max_sector = ( VDISK_SECTORS_PER_TRACK - 0 /* sic */ );
  64         unsigned int num_drives;
  65         unsigned int min_num_drives;
  66
  67         /* Calculate number of drives to report */
  68         num_drives = INT13_DRIVE_COUNT;
  69         min_num_drives = ( ( vdisk_drive & 0x7f ) + 1 );
  70         if ( num_drives < min_num_drives )
  71                 num_drives = min_num_drives;
  72
  73         /* Fill in drive parameters */
  74         params->ch = ( max_cylinder & 0xff );
  75         params->cl = ( ( ( max_cylinder >> 8 ) << 6 ) | max_sector );
  76         params->dh = max_head;
  77         params->dl = num_drives;
  78         DBG2 ( "Get parameters: C/H/S = %d/%d/%d, drives = %d\n",
  79                ( max_cylinder + 1 ), ( max_head + 1 ), max_sector, num_drives );
  80
  81         /* Success */
  82         params->ah = 0;
  83 }
  84
  85 /**
  86  * INT 13, 15 - Get disk type
  87  *
  88  * @ret cx:dx           Sector count
  89  * @ret ah              Type code
  90  */
  91 static void int13_get_disk_type ( struct bootapp_callback_params *params ) {
  92         uint32_t sector_count = VDISK_COUNT;
  93         uint8_t drive_type = INT13_DISK_TYPE_HDD;
  94
  95         /* Fill in disk type */
  96         params->cx = ( sector_count >> 16 );
  97         params->dx = ( sector_count & 0xffff );
  98         params->ah = drive_type;
  99         DBG2 ( "Get disk type: sectors = %#08x, type = %d\n",
 100                sector_count, drive_type );
 101 }
 102
 103 /**
 104  * INT 13, 41 - Extensions installation check
 105  *
 106  * @v bx                0x55aa
 107  * @ret bx              0xaa55
 108  * @ret cx              Extensions API support bitmap
 109  * @ret ah              API version
 110  */
 111 static void int13_extension_check ( struct bootapp_callback_params *params ) {
 112
 113         /* Fill in extension information */
 114         params->bx = 0xaa55;
 115         params->cx = INT13_EXTENSION_LINEAR;
 116         params->ah = INT13_EXTENSION_VER_1_X;
 117         DBG2 ( "Extensions installation check\n" );
 118 }
 119
 120 /**
 121  * INT 13, 48 - Get extended parameters
 122  *
 123  * @v ds:si             Drive parameter table
 124  * @ret ah              Status code
 125  */
 126 static void
 127 int13_get_extended_parameters ( struct bootapp_callback_params *params ) {
 128         struct int13_disk_parameters *disk_params;
 129
 130         /* Fill in extended parameters */
 131         disk_params = REAL_PTR ( params->ds, params->si );
 132         memset ( disk_params, 0, sizeof ( *disk_params ) );
 133         disk_params->bufsize = sizeof ( *disk_params );
 134         disk_params->flags = INT13_FL_DMA_TRANSPARENT;
 135         disk_params->cylinders = VDISK_CYLINDERS;
 136         disk_params->heads = VDISK_HEADS;
 137         disk_params->sectors_per_track = VDISK_SECTORS_PER_TRACK;
 138         disk_params->sectors = VDISK_COUNT;
 139         disk_params->sector_size = VDISK_SECTOR_SIZE;
 140         DBG2 ( "Get extended parameters: C/H/S = %d/%d/%d, sectors = %#08llx "
 141                "(%d bytes)\n", disk_params->cylinders, disk_params->heads,
 142                disk_params->sectors_per_track, disk_params->sectors,
 143                disk_params->sector_size );
 144
 145         /* Success */
 146         params->ah = 0;
 147 }
 148
 149 /**
 150  * INT 13, 42 - Extended read
 151  *
 152  * @v ds:si             Disk address packet
 153  * @ret ah              Status code
 154  */
 155 static void int13_extended_read ( struct bootapp_callback_params *params ) {
 156         struct int13_disk_address *disk_address;
 157         void *data;
 158
 159         /* Read from emulated disk */
 160         disk_address = REAL_PTR ( params->ds, params->si );
 161         data = REAL_PTR ( disk_address->buffer.segment,
 162                           disk_address->buffer.offset );
 163         vdisk_read ( disk_address->lba, disk_address->count, data );
 164
 165         /* Success */
 166         params->ah = 0;
 167 }
 168
 169 /**
 170  * Emulate INT 13 drive
 171  *
 172  * @v params            Parameters
 173  */
 174 void emulate_int13 ( struct bootapp_callback_params *params ) {
 175         int command = params->ah;
 176         int drive = params->dl;
 177         int min_num_drives;
 178         unsigned long eflags;
 179
 180         if ( drive == vdisk_drive ) {
 181
 182                 /* Emulated drive - handle internally */
 183
 184                 /* Populate eflags with a sensible starting value */
 185                 __asm__ ( "pushf\n\t"
 186                           "pop %0\n\t"
 187                           : "=r" ( eflags ) );
 188                 params->eflags = ( eflags & ~CF );
 189
 190                 /* Handle command */
 191                 switch ( command ) {
 192                 case INT13_GET_PARAMETERS:
 193                         int13_get_parameters ( params );
 194                         break;
 195                 case INT13_GET_DISK_TYPE:
 196                         int13_get_disk_type ( params );
 197                         break;
 198                 case INT13_EXTENSION_CHECK:
 199                         int13_extension_check ( params );
 200                         break;
 201                 case INT13_GET_EXTENDED_PARAMETERS:
 202                         int13_get_extended_parameters ( params );
 203                         break;
 204                 case INT13_EXTENDED_READ:
 205                         int13_extended_read ( params );
 206                         break;
 207                 default:
 208                         DBG ( "Unrecognised INT 13,%02x\n", command );
 209                         params->eflags |= CF;
 210                         break;
 211                 }
 212
 213         } else {
 214
 215                 /* Pass through command to underlying INT 13 */
 216                 call_interrupt ( params );
 217
 218                 /* Modify drive count, if applicable */
 219                 if ( command == INT13_GET_PARAMETERS ) {
 220                         min_num_drives = ( ( vdisk_drive & 0x7f ) + 1 );
 221                         if ( params->dl < min_num_drives )
 222                                 params->dl = min_num_drives;
 223                 }
 224         }
 225 }