1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
|
/* $OpenBSD: gateA20.c,v 1.9 2003/08/11 06:23:09 deraadt Exp $ */
/*
* Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
*
* Mach Operating System
* Copyright (c) 1992, 1991 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*/
#include <sys/param.h>
#include <sys/types.h>
#include <machine/pio.h>
#include <dev/ic/i8042reg.h>
#include <dev/isa/isareg.h>
#include "libsa.h"
#define KB_A20 0xdf /* enable A20,
enable output buffer full interrupt
enable data line
enable clock line */
/*
* Gate A20 for high memory
*/
void
gateA20(int on)
{
if (ps2model == 0xf82 ||
(inb(IO_KBD + KBSTATP) == 0xff && inb(IO_KBD + KBDATAP) == 0xff)) {
int data;
/* Try to use 0x92 to turn on A20 */
if (on) {
data = inb(0x92);
outb(0x92, data | 0x2);
} else {
data = inb(0x92);
outb(0x92, data & ~0x2);
}
} else {
while (inb(IO_KBD + KBSTATP) & KBS_IBF);
while (inb(IO_KBD + KBSTATP) & KBS_DIB)
(void)inb(IO_KBD + KBDATAP);
outb(IO_KBD + KBCMDP, KBC_CMDWOUT);
while (inb(IO_KBD + KBSTATP) & KBS_IBF);
if (on)
outb(IO_KBD + KBDATAP, KB_A20);
else
outb(IO_KBD + KBDATAP, 0xcd);
while (inb(IO_KBD + KBSTATP) & KBS_IBF);
while (inb(IO_KBD + KBSTATP) & KBS_DIB)
(void)inb(IO_KBD + KBDATAP);
}
}
|
