xref: /netbsd/sys/arch/i386/stand/lib/biosmca.S (revision bf9ec67e)
1/*	$NetBSD: biosmca.S,v 1.2 2001/05/14 22:14:47 jdolecek Exp $	*/
2
3/*
4 * Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
5 *
6 * Mach Operating System
7 * Copyright (c) 1992, 1991 Carnegie Mellon University
8 * All Rights Reserved.
9 *
10 * Permission to use, copy, modify and distribute this software and its
11 * documentation is hereby granted, provided that both the copyright
12 * notice and this permission notice appear in all copies of the
13 * software, derivative works or modified versions, and any portions
14 * thereof, and that both notices appear in supporting documentation.
15 *
16 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
17 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
18 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
19 *
20 * Carnegie Mellon requests users of this software to return to
21 *
22 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
23 *  School of Computer Science
24 *  Carnegie Mellon University
25 *  Pittsburgh PA 15213-3890
26 *
27 * any improvements or extensions that they make and grant Carnegie Mellon
28 * the rights to redistribute these changes.
29 */
30
31/*
32  Copyright 1988, 1989, 1990, 1991, 1992
33   by Intel Corporation, Santa Clara, California.
34
35                All Rights Reserved
36
37Permission to use, copy, modify, and distribute this software and
38its documentation for any purpose and without fee is hereby
39granted, provided that the above copyright notice appears in all
40copies and that both the copyright notice and this permission notice
41appear in supporting documentation, and that the name of Intel
42not be used in advertising or publicity pertaining to distribution
43of the software without specific, written prior permission.
44
45INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
46INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
47IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
48CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
49LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
50NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
51WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
52*/
53
54/* extracted from netbsd:sys/arch/i386/stand/bios_disk.S */
55
56#include <machine/asm.h>
57
58#define	addr32	.byte 0x67
59#define	data32	.byte 0x66
60
61	.data
62	.globl _C_LABEL(biosmca_ps2model)
63_C_LABEL(biosmca_ps2model):	.long 0
64
65	.text
66/*
67# BIOS call "INT 0x15 Function 0xc0" to read extended sys config info on PS/2
68#	Return:		no return value
69#
70# This function initializes biosmca_ps2model with model number as
71# identified by BIOS, if the machine is a PS/2 box (i.e. has MCA bus
72# instead of ISA).
73*/
74ENTRY(biosmca)
75	pushl	%ebp
76	movl    %esp, %ebp
77	pushl	%ebx
78	push	%ecx
79	push	%edx
80	push	%esi
81	push	%edi
82	push	%eax
83
84	call	_C_LABEL(prot_to_real)	# enter real mode
85
86	# zero %cx
87	data32
88	xorl	%cx, %cx
89
90	data32
91	xorl	%ax, %ax
92	movb	$0xc0, %ah	# subfunction
93	int	$0x15
94	jc	back
95
96	# check feature byte 1 if MCA bus present and replaces ISA
97	addr32
98	movb	%es:5(%ebx), %ax
99	andw	$0x02, %ax	# bit 1 set means MCA instead of ISA
100	cmpw	$0x02, %ax	# see also arch/i386/mca/mca_machdep.c
101	jne	back
102
103	# save model and submodel bytes to %cx
104	addr32
105	movb	%es:2(%ebx), %ch	# model (1 byte)
106	addr32
107	movb	%es:3(%ebx), %cl	# submodel (1 byte)
108
109back:
110	data32
111	call	_C_LABEL(real_to_prot) # back to protected mode
112
113	# save model
114	movl	%ecx, _C_LABEL(biosmca_ps2model)
115
116	pop	%eax
117	pop	%edi
118	pop	%esi
119	pop	%edx
120	pop	%ecx
121	popl	%ebx
122	popl	%ebp
123	ret
124