lib_i386/bios.S

   1 /*
   2  * (C) Copyright 2002
   3  * Daniel Engström, Omicron Ceti AB, daniel@omicron.se
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23
  24 /*
  25  * Based on msbios.c from rolo 1.6:
  26  *----------------------------------------------------------------------
  27  * (C) Copyright 2000
  28  * Sysgo Real-Time Solutions GmbH
  29  * Klein-Winternheim, Germany
  30  *----------------------------------------------------------------------
  31  */
  32
  33 #include "bios.h"
  34
  35 /*
  36  * During it's initialization phase, before switching to protected
  37  * mode, the Linux Kernel makes a few BIOS calls. This won't work
  38  * if the board does not have a BIOS.
  39  *
  40  * This is a very minimalisic BIOS that supplies just enough
  41  * functionality to keep the Linux Kernel happy. It is NOT
  42  * a general purpose replacement for a real BIOS !!
  43  */
  44
  45
  46 .section .bios, "ax"
  47 .code16
  48 .org 0
  49         /* a call to f000:0 should warmboot */
  50         jmp     realmode_reset
  51
  52 .globl rm_int00
  53 rm_int00:
  54         pushw   $0
  55         jmp     any_interrupt16
  56 .globl rm_int01
  57 rm_int01:
  58         pushw   $1
  59         jmp     any_interrupt16
  60 .globl rm_int02
  61 rm_int02:
  62         pushw   $2
  63         jmp     any_interrupt16
  64 .globl rm_int03
  65 rm_int03:
  66         pushw   $3
  67         jmp     any_interrupt16
  68 .globl rm_int04
  69 rm_int04:
  70         pushw   $4
  71         jmp     any_interrupt16
  72 .globl rm_int05
  73 rm_int05:
  74         pushw   $5
  75         jmp     any_interrupt16
  76 .globl rm_int06
  77 rm_int06:
  78         pushw   $6
  79         jmp     any_interrupt16
  80 .globl rm_int07
  81 rm_int07:
  82         pushw   $7
  83         jmp     any_interrupt16
  84 .globl rm_int08
  85 rm_int08:
  86         pushw   $8
  87         jmp     any_interrupt16
  88 .globl rm_int09
  89 rm_int09:
  90         pushw   $9
  91         jmp     any_interrupt16
  92 .globl rm_int0a
  93 rm_int0a:
  94         pushw   $10
  95         jmp     any_interrupt16
  96 .globl rm_int0b
  97 rm_int0b:
  98         pushw   $11
  99         jmp     any_interrupt16
 100 .globl rm_int0c
 101 rm_int0c:
 102         pushw   $12
 103         jmp     any_interrupt16
 104 .globl rm_int0d
 105 rm_int0d:
 106         pushw   $13
 107         jmp     any_interrupt16
 108 .globl rm_int0e
 109 rm_int0e:
 110         pushw   $14
 111         jmp     any_interrupt16
 112 .globl rm_int0f
 113 rm_int0f:
 114         pushw   $15
 115         jmp     any_interrupt16
 116 .globl rm_int10
 117 rm_int10:
 118         pushw   $16
 119         jmp     any_interrupt16
 120 .globl rm_int11
 121 rm_int11:
 122         pushw   $17
 123         jmp     any_interrupt16
 124 .globl rm_int12
 125 rm_int12:
 126         pushw   $18
 127         jmp     any_interrupt16
 128 .globl rm_int13
 129 rm_int13:
 130         pushw   $19
 131         jmp     any_interrupt16
 132 .globl rm_int14
 133 rm_int14:
 134         pushw   $20
 135         jmp     any_interrupt16
 136 .globl rm_int15
 137 rm_int15:
 138         pushw   $21
 139         jmp     any_interrupt16
 140 .globl rm_int16
 141 rm_int16:
 142         pushw   $22
 143         jmp     any_interrupt16
 144 .globl rm_int17
 145 rm_int17:
 146         pushw   $23
 147         jmp     any_interrupt16
 148 .globl rm_int18
 149 rm_int18:
 150         pushw   $24
 151         jmp     any_interrupt16
 152 .globl rm_int19
 153 rm_int19:
 154         pushw   $25
 155         jmp     any_interrupt16
 156 .globl rm_int1a
 157 rm_int1a:
 158         pushw   $26
 159         jmp     any_interrupt16
 160 .globl rm_int1b
 161 rm_int1b:
 162         pushw   $27
 163         jmp     any_interrupt16
 164 .globl rm_int1c
 165 rm_int1c:
 166         pushw   $28
 167         jmp     any_interrupt16
 168 .globl rm_int1d
 169 rm_int1d:
 170         pushw   $29
 171         jmp     any_interrupt16
 172 .globl rm_int1e
 173 rm_int1e:
 174         pushw   $30
 175         jmp     any_interrupt16
 176 .globl rm_int1f
 177 rm_int1f:
 178         pushw   $31
 179         jmp     any_interrupt16
 180 .globl rm_def_int
 181 rm_def_int:
 182         iret
 183
 184
 185         /*
 186          * All interrupt jumptable entries jump to here
 187          * after pushing the interrupt vector number onto the
 188          * stack.
 189          */
 190 any_interrupt16:
 191         MAKE_BIOS_STACK
 192
 193 gs      movw    OFFS_VECTOR(%bp), %ax
 194         cmpw    $0x10, %ax
 195         je      Lint_10h
 196         cmpw    $0x11, %ax
 197         je      Lint_11h
 198         cmpw    $0x12, %ax
 199         je      Lint_12h
 200         cmpw    $0x13, %ax
 201         je      Lint_13h
 202         cmpw    $0x15, %ax
 203         je      Lint_15h
 204         cmpw    $0x16, %ax
 205         je      Lint_16h
 206         cmpw    $0x1a, %ax
 207         je      Lint_1ah
 208         movw    $0xffff, %ax
 209         jmp     Lout
 210 Lint_10h:                                       /* VGA BIOS services */
 211         call    bios_10h
 212         jmp     Lout
 213 Lint_11h:
 214         call    bios_11h
 215         jmp     Lout
 216 Lint_12h:
 217         call    bios_12h
 218         jmp     Lout
 219 Lint_13h:                                       /* BIOS disk services */
 220         call    bios_13h
 221         jmp     Lout
 222 Lint_15h:                                       /* Misc. BIOS services */
 223         call    bios_15h
 224         jmp     Lout
 225 Lint_16h:                                       /* keyboard services */
 226         call    bios_16h
 227         jmp     Lout
 228 Lint_1ah:                                       /* PCI bios */
 229         call    bios_1ah
 230         jmp     Lout
 231 Lout:
 232         cmpw    $0, %ax
 233         je      Lhandeled
 234
 235         /* Insert code for unhandeled INTs here.
 236          *
 237          * ROLO prints a message to the console
 238          * (we could do that but then we're in 16bit mode
 239          * so we'll have to get back into 32bit mode
 240          * to use the console I/O routines (if we do this
 241          * we shuls make int 0x10 and int 0x16 work as well))
 242          */
 243 Lhandeled:
 244         RESTORE_CALLERS_STACK
 245         addw    $2,%sp                          /* dump vector number */
 246         iret                                    /* return from interrupt */
 247
 248
 249 /*
 250  ************************************************************
 251  * BIOS interrupt 10h -- VGA services
 252  ************************************************************
 253  */
 254 bios_10h:
 255 gs      movw    OFFS_AX(%bp), %ax
 256         shrw    $8, %ax
 257         cmpw    $0x3, %ax
 258         je      Lcur_pos
 259         cmpw    $0xf, %ax
 260         je      Lvid_state
 261         cmpw    $0x12, %ax
 262         je      Lvid_cfg
 263         movw    $0xffff, %ax
 264         ret
 265 Lcur_pos:                                       /* Read Cursor Position and Size */
 266 gs      movw    $0, OFFS_CX(%bp)
 267 gs      movw    $0, OFFS_DX(%bp)
 268         xorw    %ax, %ax
 269         ret
 270 Lvid_state:                                     /* Get Video State */
 271 gs      movw    $(80 << 8|0x03), OFFS_AX(%bp)   /* 80 columns, 80x25, 16 colors */
 272 gs      movw    $0, OFFS_BX(%bp)
 273         xorw    %ax, %ax
 274         ret
 275 Lvid_cfg:       /* Video Subsystem Configuration (EGA/VGA) */
 276 gs      movw    $0x10, OFFS_BX(%bp)             /* indicate CGA/MDA/HGA */
 277         xorw    %ax, %ax
 278         ret
 279
 280
 281 /*
 282  ************************************************************
 283  * BIOS interrupt 11h -- Equipment determination
 284  ************************************************************
 285  */
 286
 287 bios_11h:
 288 cs      movw    bios_equipment, %ax
 289 gs      movw    %ax, OFFS_AX(%bp)
 290         xorw    %ax, %ax
 291         ret
 292
 293
 294 /*
 295  ************************************************************
 296  * BIOS interrupt 12h -- Get Memory Size
 297  ************************************************************
 298  */
 299 bios_12h:
 300 cs      movw    ram_in_64kb_chunks, %ax
 301         cmpw    $0xa, %ax
 302         ja      b12_more_than_640k
 303         shlw    $6, %ax
 304         jmp     b12_return
 305 b12_more_than_640k:
 306         movw    $0x280, %ax
 307 b12_return:
 308 gs      movw    %ax, OFFS_AX(%bp)               /* return number of kilobytes in ax */
 309
 310 gs      movw    OFFS_FLAGS(%bp), %ax
 311         andw    $0xfffe, %ax                    /* clear carry -- function succeeded */
 312 gs      movw    %ax, OFFS_FLAGS(%bp)
 313
 314         xorw    %ax, %ax
 315         ret
 316
 317
 318 /*
 319  ************************************************************
 320  * BIOS interrupt 13h -- Disk services
 321  ************************************************************
 322  */
 323 bios_13h:
 324 gs      movw    OFFS_AX(%bp), %ax
 325         shrw    $8, %ax
 326         cmpw    $0x15, %ax
 327         je      Lfunc_15h
 328         movw    $0xffff, %ax
 329         ret
 330 Lfunc_15h:
 331 gs      movw    OFFS_AX(%bp), %ax
 332         andw    $0xff, %ax                      /* return AH=0->drive not present */
 333 gs      movw    %ax, OFFS_AX(%bp)
 334         xorw    %ax, %ax
 335         ret
 336
 337
 338 /*
 339  ***********************************************************
 340  * BIOS interrupt 15h -- Miscellaneous services
 341  ***********************************************************
 342  */
 343 bios_15h:
 344 gs      movw    OFFS_AX(%bp), %ax
 345         shrw    $8, %ax
 346         cmpw    $0xc0, %ax
 347         je      Lfunc_c0h
 348         cmpw    $0xe8, %ax
 349         je      Lfunc_e8h
 350         cmpw    $0x88, %ax
 351         je      Lfunc_88h
 352         movw    $0xffff, %ax
 353         ret
 354
 355 Lfunc_c0h:                                      /* Return System Configuration Parameters (PS2 only) */
 356 gs      movw    OFFS_FLAGS(%bp), %ax
 357         orw     $1, %ax                         /* return carry -- function not supported */
 358 gs      movw    %ax, OFFS_FLAGS(%bp)
 359         xorw    %ax, %ax
 360         ret
 361
 362 Lfunc_e8h:
 363 gs      movw    OFFS_AX(%bp), %ax
 364         andw    $0xff, %ax
 365         cmpw    $1, %ax
 366         je      Lfunc_e801h
 367 gs      movw    OFFS_FLAGS(%bp), %ax
 368         orw     $1, %ax                         /* return carry -- function not supported */
 369 gs      movw    %ax, OFFS_FLAGS(%bp)
 370         xorw    %ax, %ax
 371         ret
 372
 373 Lfunc_e801h:                                    /* Get memory size for >64M Configurations */
 374 cs      movw    ram_in_64kb_chunks, %ax
 375         cmpw    $0x100, %ax
 376         ja      e801_more_than_16mb
 377         shlw    $6, %ax                         /* multiply by 64 */
 378         subw    $0x400, %ax                     /* 1st meg does not count */
 379
 380 gs      movw    %ax, OFFS_AX(%bp)               /* return memory size between 1M and 16M in 1kb chunks in AX and CX */
 381 gs      movw    %ax, OFFS_CX(%bp)
 382 gs      movw    $0, OFFS_BX(%bp)                /* set BX and DX to 0*/
 383 gs      movw    $0, OFFS_DX(%bp)
 384 gs      movw    OFFS_FLAGS(%bp), %ax
 385         andw    $0xfffe, %ax                    /* clear carry -- function succeeded */
 386 gs      movw    %ax, OFFS_FLAGS(%bp)
 387         xorw    %ax, %ax
 388         ret
 389
 390 e801_more_than_16mb:
 391         subw    $0x100, %ax                     /* subtract 16MB */
 392
 393 gs      movw    $0x3c00, OFFS_AX(%bp)           /* return 0x3c00 (16MB-1MB) in AX and CX */
 394 gs      movw    $0x3c00, OFFS_CX(%bp)
 395 gs      movw    %ax, OFFS_BX(%bp)               /* set BX and DX to number of 64kb chunks above 16MB */
 396 gs      movw    %ax, OFFS_DX(%bp)
 397
 398 gs      movw    OFFS_FLAGS(%bp), %ax
 399         andw    $0xfffe, %ax                    /* clear carry -- function succeeded */
 400 gs      movw    %ax, OFFS_FLAGS(%bp)
 401         xorw    %ax, %ax
 402         ret
 403
 404 Lfunc_88h:
 405 cs      movw    ram_in_64kb_chunks, %ax
 406         cmpw    $0x100, %ax
 407         jna     b88_not_more_than16
 408         movw    $0x100, %ax
 409 b88_not_more_than16:
 410         shlw    $6, %ax
 411         subw    $0x400, %ax                     /* 1st meg does not count */
 412
 413 gs      movw    %ax, OFFS_AX(%bp)               /* return number of kilobytes between 16MB and 16MB in ax */
 414
 415 gs      movw    OFFS_FLAGS(%bp), %ax
 416         andw    $0xfffe, %ax                    /* clear carry -- function succeeded */
 417 gs      movw    %ax, OFFS_FLAGS(%bp)
 418
 419         xorw    %ax, %ax
 420         ret
 421
 422
 423 /*
 424  ************************************************************
 425  * BIOS interrupt 16h -- keyboard services
 426  ************************************************************
 427  */
 428 bios_16h:
 429 gs      movw    OFFS_AX(%bp), %ax
 430         shrw    $8, %ax
 431         cmpw    $0x03, %ax
 432         je      Lfunc_03h
 433         movw    $0xffff, %ax
 434         ret
 435 Lfunc_03h:
 436         xorw    %ax, %ax                        /* do nothing -- function not supported */
 437         ret
 438
 439 /*
 440  ************************************************************
 441  * BIOS interrupt 1ah -- PCI bios
 442  ************************************************************
 443  */
 444 bios_1ah:
 445 gs      movw    OFFS_AX(%bp), %ax
 446         cmpb    $0xb1, %ah
 447         je      Lfunc_b1h
 448         movw    $0xffff, %ax
 449         ret
 450 Lfunc_b1h:
 451         call    realmode_pci_bios
 452         xorw    %ax, %ax                        /* do nothing -- function not supported */
 453         ret
 454
 455
 456 .globl ram_in_64kb_chunks
 457 ram_in_64kb_chunks:
 458         .word   0
 459
 460 .globl bios_equipment
 461 bios_equipment:
 462         .word   0