/*
   * (C) Copyright 2002
   * Daniel Engström, Omicron Ceti AB, daniel@omicron.se

   *

   * See file CREDITS for list of people who contributed to this
   * project.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as
   * published by the Free Software Foundation; either version 2 of
   * the License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
   * MA 02111-1307 USA
   */
  
  /*
   * Based on msbios.c from rolo 1.6:
   *----------------------------------------------------------------------
   * (C) Copyright 2000
   * Sysgo Real-Time Solutions GmbH
   * Klein-Winternheim, Germany
   *----------------------------------------------------------------------
   */

  #include "bios.h"

  /*
   * During it's initialization phase, before switching to protected
   * mode, the Linux Kernel makes a few BIOS calls. This won't work
   * if the board does not have a BIOS.
   *
   * This is a very minimalisic BIOS that supplies just enough
   * functionality to keep the Linux Kernel happy. It is NOT
   * a general purpose replacement for a real BIOS !!
   */

  
  .section .bios, "ax"
  .code16
  .org 0

  	/* a call to f000:0 should warmboot */

  	jmp	realmode_reset

  .globl rm_int00
  rm_int00:
  	pushw	$0
  	jmp	any_interrupt16
  .globl rm_int01
  rm_int01:
  	pushw	$1
  	jmp	any_interrupt16
  .globl rm_int02
  rm_int02:
  	pushw	$2
  	jmp	any_interrupt16
  .globl rm_int03
  rm_int03:
  	pushw	$3
  	jmp	any_interrupt16
  .globl rm_int04
  rm_int04:
  	pushw	$4
  	jmp	any_interrupt16
  .globl rm_int05
  rm_int05:
  	pushw	$5
  	jmp	any_interrupt16
  .globl rm_int06
  rm_int06:
  	pushw	$6
  	jmp	any_interrupt16
  .globl rm_int07
  rm_int07:
  	pushw	$7
  	jmp	any_interrupt16
  .globl rm_int08
  rm_int08:
  	pushw	$8
  	jmp	any_interrupt16
  .globl rm_int09
  rm_int09:
  	pushw	$9
  	jmp	any_interrupt16
  .globl rm_int0a
  rm_int0a:
  	pushw	$10
  	jmp	any_interrupt16
  .globl rm_int0b
  rm_int0b:
  	pushw	$11
  	jmp	any_interrupt16
  .globl rm_int0c
  rm_int0c:
  	pushw	$12
  	jmp	any_interrupt16
  .globl rm_int0d
  rm_int0d:
  	pushw	$13
  	jmp	any_interrupt16
  .globl rm_int0e
  rm_int0e:
  	pushw	$14
  	jmp	any_interrupt16
  .globl rm_int0f
  rm_int0f:
  	pushw	$15
  	jmp	any_interrupt16
  .globl rm_int10
  rm_int10:
  	pushw	$16
  	jmp	any_interrupt16
  .globl rm_int11
  rm_int11:
  	pushw	$17
  	jmp	any_interrupt16
  .globl rm_int12
  rm_int12:
  	pushw	$18
  	jmp	any_interrupt16
  .globl rm_int13
  rm_int13:
  	pushw	$19
  	jmp	any_interrupt16
  .globl rm_int14
  rm_int14:
  	pushw	$20
  	jmp	any_interrupt16
  .globl rm_int15
  rm_int15:
  	pushw	$21
  	jmp	any_interrupt16
  .globl rm_int16
  rm_int16:
  	pushw	$22
  	jmp	any_interrupt16
  .globl rm_int17
  rm_int17:
  	pushw	$23
  	jmp	any_interrupt16
  .globl rm_int18
  rm_int18:
  	pushw	$24
  	jmp	any_interrupt16
  .globl rm_int19
  rm_int19:
  	pushw	$25
  	jmp	any_interrupt16
  .globl rm_int1a
  rm_int1a:
  	pushw	$26
  	jmp	any_interrupt16
  .globl rm_int1b
  rm_int1b:
  	pushw	$27
  	jmp	any_interrupt16
  .globl rm_int1c
  rm_int1c:
  	pushw	$28
  	jmp	any_interrupt16
  .globl rm_int1d
  rm_int1d:
  	pushw	$29
  	jmp	any_interrupt16
  .globl rm_int1e
  rm_int1e:
  	pushw	$30
  	jmp	any_interrupt16
  .globl rm_int1f
  rm_int1f:
  	pushw	$31
  	jmp	any_interrupt16
  .globl rm_def_int
  rm_def_int:
  	iret

  	/*
  	 * All interrupt jumptable entries jump to here
  	 * after pushing the interrupt vector number onto the
  	 * stack.
  	 */
  any_interrupt16:

  	MAKE_BIOS_STACK

  
  gs	movw	OFFS_VECTOR(%bp), %ax
  	cmpw	$0x10, %ax

  	je	Lint_10h

  	cmpw	$0x11, %ax
  	je	Lint_11h

  	cmpw	$0x12, %ax
  	je	Lint_12h

  	cmpw	$0x13, %ax
  	je	Lint_13h
  	cmpw	$0x15, %ax
  	je	Lint_15h
  	cmpw	$0x16, %ax
  	je	Lint_16h

  	cmpw	$0x1a, %ax
  	je	Lint_1ah

  	movw	$0xffff, %ax
  	jmp	Lout
  Lint_10h:					/* VGA BIOS services */
  	call	bios_10h
  	jmp	Lout

  Lint_11h:

  	call	bios_11h
  	jmp	Lout

  Lint_12h:

  	call	bios_12h
  	jmp	Lout

  Lint_13h:					/* BIOS disk services */
  	call	bios_13h
  	jmp	Lout
  Lint_15h:					/* Misc. BIOS services */
  	call	bios_15h
  	jmp	Lout
  Lint_16h:					/* keyboard services */
  	call	bios_16h
  	jmp	Lout

  Lint_1ah:					/* PCI bios */
  	call	bios_1ah
  	jmp	Lout

  Lout:

  	cmpw	$0, %ax
  	je	Lhandeled

  	/* Insert code for unhandeled INTs here.
  	 *

  	 * ROLO prints a message to the console

  	 * (we could do that but then we're in 16bit mode
  	 * so we'll have to get back into 32bit mode
  	 * to use the console I/O routines (if we do this
  	 * we shuls make int 0x10 and int 0x16 work as well))
  	 */
  Lhandeled:

  	RESTORE_CALLERS_STACK

  	addw	$2,%sp				/* dump vector number */
  	iret					/* return from interrupt */
  
  
  /*
   ************************************************************
   * BIOS 	interrupt 10h -- VGA services
   ************************************************************
   */
  bios_10h:
  gs	movw	OFFS_AX(%bp), %ax
  	shrw	$8, %ax
  	cmpw	$0x3, %ax
  	je	Lcur_pos
  	cmpw	$0xf, %ax
  	je	Lvid_state
  	cmpw	$0x12, %ax
  	je	Lvid_cfg
  	movw	$0xffff, %ax
  	ret
  Lcur_pos:					/* Read Cursor Position and Size */
  gs	movw	$0, OFFS_CX(%bp)
  gs	movw	$0, OFFS_DX(%bp)
  	xorw	%ax, %ax
  	ret
  Lvid_state:					/* Get Video State */
  gs	movw	$(80 << 8|0x03), OFFS_AX(%bp)	/* 80 columns, 80x25, 16 colors */
  gs	movw	$0, OFFS_BX(%bp)
  	xorw	%ax, %ax
  	ret
  Lvid_cfg:	/* Video Subsystem Configuration (EGA/VGA) */
  gs	movw	$0x10, OFFS_BX(%bp)		/* indicate CGA/MDA/HGA */
  	xorw	%ax, %ax
  	ret
  
  
  /*
   ************************************************************
   * BIOS interrupt 11h -- Equipment determination
   ************************************************************
   */
  
  bios_11h:

  cs	movw	bios_equipment, %ax

  gs	movw	%ax, OFFS_AX(%bp)

  	xorw	%ax, %ax
  	ret
  
  
  /*
   ************************************************************

   * BIOS 	interrupt 12h -- Get Memory Size
   ************************************************************
   */
  bios_12h:
  cs	movw	ram_in_64kb_chunks, %ax
  	cmpw	$0xa, %ax
  	ja	b12_more_than_640k
  	shlw	$6, %ax
  	jmp	b12_return
  b12_more_than_640k:
  	movw	$0x280, %ax
  b12_return:
  gs	movw	%ax, OFFS_AX(%bp)		/* return number of kilobytes in ax */
  
  gs	movw	OFFS_FLAGS(%bp), %ax
  	andw	$0xfffe, %ax			/* clear carry -- function succeeded */
  gs	movw	%ax, OFFS_FLAGS(%bp)
  
  	xorw	%ax, %ax
  	ret
  
  
  /*
   ************************************************************

   * BIOS interrupt 13h -- Disk services
   ************************************************************
   */
  bios_13h:
  gs	movw	OFFS_AX(%bp), %ax
  	shrw	$8, %ax
  	cmpw	$0x15, %ax
  	je	Lfunc_15h
  	movw	$0xffff, %ax
  	ret

  Lfunc_15h:

  gs	movw	OFFS_AX(%bp), %ax
  	andw	$0xff, %ax			/* return AH=0->drive not present */
  gs	movw	%ax, OFFS_AX(%bp)
  	xorw	%ax, %ax
  	ret

  
  /*
   ***********************************************************
   * BIOS interrupt 15h -- Miscellaneous services
   ***********************************************************
   */
  bios_15h:
  gs	movw	OFFS_AX(%bp), %ax
  	shrw	$8, %ax
  	cmpw	$0xc0, %ax
  	je	Lfunc_c0h
  	cmpw	$0xe8, %ax
  	je	Lfunc_e8h
  	cmpw	$0x88, %ax
  	je	Lfunc_88h
  	movw	$0xffff, %ax
  	ret
  
  Lfunc_c0h: 					/* Return System Configuration Parameters (PS2 only) */
  gs	movw	OFFS_FLAGS(%bp), %ax
  	orw	$1, %ax				/* return carry -- function not supported */
  gs	movw	%ax, OFFS_FLAGS(%bp)
  	xorw	%ax, %ax
  	ret

  Lfunc_e8h:
  gs	movw	OFFS_AX(%bp), %ax
  	andw	$0xff, %ax
  	cmpw	$1, %ax
  	je	Lfunc_e801h
  gs	movw	OFFS_FLAGS(%bp), %ax
  	orw	$1, %ax				/* return carry -- function not supported */
  gs	movw	%ax, OFFS_FLAGS(%bp)
  	xorw	%ax, %ax
  	ret

  Lfunc_e801h:					/* Get memory size for >64M Configurations */

  cs	movw	ram_in_64kb_chunks, %ax
  	cmpw	$0x100, %ax
  	ja	e801_more_than_16mb
  	shlw	$6, %ax				/* multiply by 64 */
  	subw	$0x400, %ax			/* 1st meg does not count */

  gs	movw	%ax, OFFS_AX(%bp)   		/* return memory size between 1M and 16M in 1kb chunks in AX and CX */

  gs	movw	%ax, OFFS_CX(%bp)

  gs	movw	$0, OFFS_BX(%bp)		/* set BX and DX to 0*/

  gs	movw	$0, OFFS_DX(%bp)

  gs	movw	OFFS_FLAGS(%bp), %ax
  	andw	$0xfffe, %ax			/* clear carry -- function succeeded */
  gs	movw	%ax, OFFS_FLAGS(%bp)
  	xorw	%ax, %ax
  	ret

  e801_more_than_16mb:

  	subw	$0x100, %ax			/* subtract 16MB */

  gs	movw	$0x3c00, OFFS_AX(%bp)		/* return 0x3c00 (16MB-1MB) in AX and CX */

  gs	movw	$0x3c00, OFFS_CX(%bp)

  gs	movw	%ax, OFFS_BX(%bp)		/* set BX and DX to number of 64kb chunks above 16MB */

  gs	movw	%ax, OFFS_DX(%bp)

  
  gs	movw	OFFS_FLAGS(%bp), %ax
  	andw	$0xfffe, %ax			/* clear carry -- function succeeded */
  gs	movw	%ax, OFFS_FLAGS(%bp)
  	xorw	%ax, %ax
  	ret
  
  Lfunc_88h:

  cs	movw	ram_in_64kb_chunks, %ax
  	cmpw	$0x100, %ax
  	jna	b88_not_more_than16
  	movw	$0x100, %ax
  b88_not_more_than16:

  	shlw	$6, %ax

  	subw	$0x400, %ax			/* 1st meg does not count */

  gs	movw	%ax, OFFS_AX(%bp)		/* return number of kilobytes between 16MB and 16MB in ax */

  
  gs	movw	OFFS_FLAGS(%bp), %ax
  	andw	$0xfffe, %ax			/* clear carry -- function succeeded */
  gs	movw	%ax, OFFS_FLAGS(%bp)
  
  	xorw	%ax, %ax
  	ret
  
  
  /*
   ************************************************************
   * BIOS interrupt 16h -- keyboard services
   ************************************************************
   */
  bios_16h:
  gs	movw	OFFS_AX(%bp), %ax
  	shrw	$8, %ax
  	cmpw	$0x03, %ax
  	je	Lfunc_03h
  	movw	$0xffff, %ax
  	ret
  Lfunc_03h:
  	xorw	%ax, %ax			/* do nothing -- function not supported */
  	ret

  /*
   ************************************************************
   * BIOS interrupt 1ah -- PCI bios
   ************************************************************
   */
  bios_1ah:
  gs	movw	OFFS_AX(%bp), %ax
  	cmpb	$0xb1, %ah
  	je	Lfunc_b1h
  	movw	$0xffff, %ax
  	ret
  Lfunc_b1h:
  	call	realmode_pci_bios
  	xorw	%ax, %ax			/* do nothing -- function not supported */
  	ret

  
  .globl ram_in_64kb_chunks
  ram_in_64kb_chunks:
  	.word 	0
  
  .globl bios_equipment
  bios_equipment:
  	.word 	0