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/*
* (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
*/
#include <common.h>
#include <asm/io.h>
#include <asm/ptrace.h>
#include <asm/realmode.h>
#define REALMODE_MAILBOX ((char *)0xe00)
int realmode_setup(void)
{
/*
* The realmode section is not relocated and still in the ROM. The
* __realmode_start symbol was adjusted, though, so adjust it back.
*/
ulong realmode_start = (ulong)&__realmode_start - gd->reloc_off;
ulong realmode_size = (ulong)&__realmode_size;
/* copy the realmode switch code */
if (realmode_size > (REALMODE_MAILBOX - (char *)REALMODE_BASE)) {
printf("realmode switch too large (%ld bytes, max is %d)\n",
realmode_size,
(int)(REALMODE_MAILBOX - (char *)REALMODE_BASE));
return -1;
}
memcpy((char *)REALMODE_BASE, (void *)realmode_start, realmode_size);
asm("wbinvd\n");
return 0;
}
int enter_realmode(u16 seg, u16 off, struct pt_regs *in, struct pt_regs *out)
{
/* setup out thin bios emulation */
if (bios_setup())
return -1;
if (realmode_setup())
return -1;
in->eip = off;
in->xcs = seg;
if ((in->esp & 0xffff) < 4)
printf("Warning: entering realmode with sp < 4 will fail\n");
memcpy(REALMODE_MAILBOX, in, sizeof(struct pt_regs));
asm("wbinvd\n");
__asm__ volatile (
"lcall $0x20,%0\n" : : "i" (&realmode_enter));
asm("wbinvd\n");
memcpy(out, REALMODE_MAILBOX, sizeof(struct pt_regs));
return out->eax;
}
/*
* This code is supposed to access a realmode interrupt
* it does currently not work for me
*/
int enter_realmode_int(u8 lvl, struct pt_regs *in, struct pt_regs *out)
{
/* place two instructions at 0x700 */
writeb(0xcd, 0x700); /* int $lvl */
writeb(lvl, 0x701);
writeb(0xcb, 0x702); /* lret */
asm("wbinvd\n");
enter_realmode(0x00, 0x700, in, out);
return out->eflags & 0x00000001;
}
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