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biosmca.S revision 1.4 
      1 /*	$NetBSD: biosmca.S,v 1.4 2003/02/01 14:48:18 dsl Exp $	*/
      2 
      3 /*
      4  * Ported to boot 386BSD by Julian Elischer (julian (at) 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 (at) 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 
     37 Permission to use, copy, modify, and distribute this software and
     38 its documentation for any purpose and without fee is hereby
     39 granted, provided that the above copyright notice appears in all
     40 copies and that both the copyright notice and this permission notice
     41 appear in supporting documentation, and that the name of Intel
     42 not be used in advertising or publicity pertaining to distribution
     43 of the software without specific, written prior permission.
     44 
     45 INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
     46 INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
     47 IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
     48 CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
     49 LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
     50 NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
     51 WITH 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 	.data
     59 	.globl _C_LABEL(biosmca_ps2model)
     60 _C_LABEL(biosmca_ps2model):	.long 0
     61 
     62 	.text
     63 /*
     64 # BIOS call "INT 0x15 Function 0xc0" to read extended sys config info on PS/2
     65 #	Return:		no return value
     66 #
     67 # This function initializes biosmca_ps2model with model number as
     68 # identified by BIOS, if the machine is a PS/2 box (i.e. has MCA bus
     69 # instead of ISA).
     70 */
     71 ENTRY(biosmca)
     72 	.code32
     73 	pushl	%ebp
     74 	movl    %esp, %ebp
     75 	pushl	%ebx
     76 	push	%ecx
     77 	push	%edx
     78 	push	%esi
     79 	push	%edi
     80 	push	%eax
     81 
     82 	call	_C_LABEL(prot_to_real)	# enter real mode
     83 	.code16
     84 
     85 	# zero %ecx
     86 	xorl	%ecx, %ecx
     87 
     88 	xor	%ax, %ax
     89 	movb	$0xc0, %ah		# subfunction
     90 	int	$0x15
     91 	jc	back
     92 
     93 	# check feature byte 1 if MCA bus present and replaces ISA
     94 	movb	%es:5(%bx), %al
     95 	andb	$0x02, %al	# bit 1 set means MCA instead of ISA
     96 				# see also arch/i386/mca/mca_machdep.c
     97 	jnz	back
     98 
     99 	# save model and submodel bytes to %cx
    100 	movb	%es:2(%bx), %ch		# model (1 byte)
    101 	movb	%es:3(%bx), %cl		# submodel (1 byte)
    102 
    103 back:
    104 	calll	_C_LABEL(real_to_prot)	# back to protected mode
    105 	.code32
    106 
    107 	# save model
    108 	movl	%ecx, _C_LABEL(biosmca_ps2model)
    109 
    110 	pop	%eax
    111 	pop	%edi
    112 	pop	%esi
    113 	pop	%edx
    114 	pop	%ecx
    115 	popl	%ebx
    116 	popl	%ebp
    117 	ret
    118