/* $NetBSD: pnpbioscall.S,v 1.3 2018/07/14 14:29:40 maxv Exp $ */
/*
 * Copyright (c) 1999
 *      Matthias Drochner.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions, and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <machine/asm.h>
__KERNEL_RCSID(0, "$NetBSD: pnpbioscall.S,v 1.3 2018/07/14 14:29:40 maxv Exp $");

#include "assym.h"
#include <machine/segments.h>

        .data
saveesp:
        .space  4

ENTRY(pnpbioscall)
        pushl   %ebp
        movl    %esp, %ebp
        /*
         * disable interrupts - our handlers can't deal with frames of the
         * segment we are calling, and the BIOS can't use our IDT anyway
         */
        pushfl
        cli

        /* call pnpbiostramp() */
        lcall   $GSEL(GPNPBIOSTRAMP_SEL, SEL_KPL), $0

        popfl
        popl    %ebp
        ret

ENTRY(pnpbiostramp)
        pushl   %ebx

        /* save current stack pointer */
        movl    %esp, %eax
        movl    %eax, saveesp

        /* switch to new stack */
        movl    8(%ebp), %esp /* call argument */
        movl    $GSEL(GPNPBIOSSCRATCH_SEL, SEL_KPL), %eax
        mov     %ax, %ss

        /* fake the call return address (16-bit frame) */
        mov     %cs, %ax
        push    %ax
        movl    $(1f - _C_LABEL(pnpbiostramp)), %eax
        push    %ax

        /* do a long jump */
        pushl   $GSEL(GPNPBIOSCODE_SEL, SEL_KPL)
        pushl   (_C_LABEL(pnpbios_entry))
#if 1
        /* paranoia: don't pass our ds */
        movl    $GSEL(GPNPBIOSSCRATCH_SEL, SEL_KPL), %eax
        mov     %ax, %ds
#endif
        lret

1:      /* returned from BIOS call */
        movl    $GSEL(GDATA_SEL, SEL_KPL), %ebx
#if 1
        mov     %bx, %ds
#endif
        /* back to old stack */
        mov     %bx, %ss
        movl    saveesp, %ebx
        movl    %ebx, %esp

        popl    %ebx
        lret
        .globl _C_LABEL(epnpbiostramp)
_C_LABEL(epnpbiostramp):