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wdenk2262cfe2002-11-18 00:14:45 +00001/*
2 * (C) Copyright 2002
3 * Daniel Engström, Omicron Ceti AB, daniel@omicron.se
wdenk8bde7f72003-06-27 21:31:46 +00004 *
wdenk2262cfe2002-11-18 00:14:45 +00005 * 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#include <common.h>
25#include <asm/io.h>
26#include <asm/ptrace.h>
wdenkea909b72002-11-21 23:11:29 +000027#include <asm/realmode.h>
wdenk2262cfe2002-11-18 00:14:45 +000028
29
30#define REALMODE_BASE ((char*)0x7c0)
31#define REALMODE_MAILBOX ((char*)0xe00)
32
33
Graeme Russ067f9b12010-10-07 20:03:31 +110034extern ulong __realmode_start;
35extern ulong __realmode_size;
wdenk2262cfe2002-11-18 00:14:45 +000036extern char realmode_enter;
37
wdenk7a8e9bed2003-05-31 18:35:21 +000038int realmode_setup(void)
39{
Graeme Russ067f9b12010-10-07 20:03:31 +110040 ulong realmode_start = (ulong)&__realmode_start + gd->reloc_off;
41 ulong realmode_size = (ulong)&__realmode_size;
Graeme Russcabe5792009-11-24 20:04:20 +110042
wdenk7a8e9bed2003-05-31 18:35:21 +000043 /* copy the realmode switch code */
Graeme Russ067f9b12010-10-07 20:03:31 +110044 if (realmode_size > (REALMODE_MAILBOX-REALMODE_BASE)) {
wdenk8bde7f72003-06-27 21:31:46 +000045 printf("realmode switch too large (%ld bytes, max is %d)\n",
Graeme Russ067f9b12010-10-07 20:03:31 +110046 realmode_size, (REALMODE_MAILBOX-REALMODE_BASE));
wdenk7a8e9bed2003-05-31 18:35:21 +000047 return -1;
48 }
wdenk8bde7f72003-06-27 21:31:46 +000049
Graeme Russ067f9b12010-10-07 20:03:31 +110050 memcpy(REALMODE_BASE, (void*)realmode_start, realmode_size);
wdenk7a8e9bed2003-05-31 18:35:21 +000051 asm("wbinvd\n");
wdenk8bde7f72003-06-27 21:31:46 +000052
wdenk7a8e9bed2003-05-31 18:35:21 +000053 return 0;
54}
wdenk8bde7f72003-06-27 21:31:46 +000055
wdenk2262cfe2002-11-18 00:14:45 +000056int enter_realmode(u16 seg, u16 off, struct pt_regs *in, struct pt_regs *out)
57{
wdenk8bde7f72003-06-27 21:31:46 +000058
wdenk2262cfe2002-11-18 00:14:45 +000059 /* setup out thin bios emulation */
60 if (bios_setup()) {
61 return -1;
62 }
wdenk8bde7f72003-06-27 21:31:46 +000063
wdenk7a8e9bed2003-05-31 18:35:21 +000064 if (realmode_setup()) {
wdenk2262cfe2002-11-18 00:14:45 +000065 return -1;
66 }
wdenk8bde7f72003-06-27 21:31:46 +000067
wdenk2262cfe2002-11-18 00:14:45 +000068 in->eip = off;
69 in->xcs = seg;
wdenkea909b72002-11-21 23:11:29 +000070 if (3>(in->esp & 0xffff)) {
wdenk2262cfe2002-11-18 00:14:45 +000071 printf("Warning: entering realmode with sp < 4 will fail\n");
72 }
wdenk8bde7f72003-06-27 21:31:46 +000073
wdenk2262cfe2002-11-18 00:14:45 +000074 memcpy(REALMODE_MAILBOX, in, sizeof(struct pt_regs));
wdenk7a8e9bed2003-05-31 18:35:21 +000075 asm("wbinvd\n");
wdenk8bde7f72003-06-27 21:31:46 +000076
77 __asm__ volatile (
wdenk2262cfe2002-11-18 00:14:45 +000078 "lcall $0x20,%0\n" : : "i" (&realmode_enter) );
79
wdenk7a8e9bed2003-05-31 18:35:21 +000080 asm("wbinvd\n");
wdenk2262cfe2002-11-18 00:14:45 +000081 memcpy(out, REALMODE_MAILBOX, sizeof(struct pt_regs));
82
83 return out->eax;
84}
85
wdenk7a8e9bed2003-05-31 18:35:21 +000086
87/* This code is supposed to access a realmode interrupt
88 * it does currently not work for me */
89int enter_realmode_int(u8 lvl, struct pt_regs *in, struct pt_regs *out)
90{
91 /* place two instructions at 0x700 */
92 writeb(0xcd, 0x700); /* int $lvl */
93 writeb(lvl, 0x701);
94 writeb(0xcb, 0x702); /* lret */
95 asm("wbinvd\n");
wdenk8bde7f72003-06-27 21:31:46 +000096
97 enter_realmode(0x00, 0x700, in, out);
98
wdenk7a8e9bed2003-05-31 18:35:21 +000099 return out->eflags&1;
100}