NetBSD-5.0.2/sys/arch/i386/stand/lib/bios_disk.S
/* $NetBSD: bios_disk.S,v 1.18 2005/12/11 12:17:48 christos 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.
*/
/*
Copyright 1988, 1989, 1990, 1991, 1992
by Intel Corporation, Santa Clara, California.
All Rights Reserved
Permission to use, copy, modify, and distribute this software and
its documentation for any purpose and without fee is hereby
granted, provided that the above copyright notice appears in all
copies and that both the copyright notice and this permission notice
appear in supporting documentation, and that the name of Intel
not be used in advertising or publicity pertaining to distribution
of the software without specific, written prior permission.
INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/* extracted from netbsd:sys/arch/i386/boot/bios.S */
#include <machine/asm.h>
/*
* BIOS call "INT 0x13 Function 0x0" to reset the disk subsystem
* Call with %ah = 0x0
* %dl = drive (0x80 for hard disk, 0x0 for floppy disk)
* Return:
* %al = 0x0 on success; err code on failure
*/
ENTRY(biosdisk_reset)
pushl %ebp
movl %esp, %ebp
pushl %ebx
push %edx
push %edi
movb 8(%ebp), %dl # device
call _C_LABEL(prot_to_real) # enter real mode
.code16
movb $0x0, %ah # subfunction
int $0x13
setc %bl
movb %ah, %bh # save error code
calll _C_LABEL(real_to_prot) # back to protected mode
.code32
xorl %eax, %eax
movw %bx, %ax # return value in %ax
pop %edi
pop %edx
popl %ebx
popl %ebp
ret
/*
* BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory
* Call with %ah = 0x2
* %al = number of sectors
* %ch = cylinder
* %cl = sector
* %dh = head
* %dl = drive (0x80 for hard disk, 0x0 for floppy disk)
* %es:%bx = segment:offset of buffer
* Return:
* %al = 0x0 on success; err code on failure
*
* biosdisk_read(dev, cyl, head, sect, count, buff_addr);
*
* Note: On failure, you must reset the disk with biosdisk_reset() before
* sending another command.
*/
ENTRY(biosdisk_read)
pushl %ebp
movl %esp, %ebp
pushl %ebx
push %ecx
push %edx
push %esi
push %edi
movb 16(%ebp), %dh
movw 12(%ebp), %cx
xchgb %ch, %cl # cylinder; the highest 2 bits of cyl is in %cl
rorb $2, %cl
movb 20(%ebp), %al
orb %al, %cl
incb %cl # sector; sec starts from 1, not 0
movb 8(%ebp), %dl # device
movl 28(%ebp), %ebx # buffer address (may be >64k)
movb 24(%ebp), %al # number of sectors
call _C_LABEL(prot_to_real) # enter real mode
.code16
push %bx
shrl $4, %ebx # max segment
mov %ds, %si
add %si, %bx
mov %bx, %es # %es:%bx now valid buffer address
pop %bx
and $0xf, %bx # and min offset - to avoid overrun
movb $0x2, %ah # subfunction
int $0x13
setc %al # error code is in %ah
calll _C_LABEL(real_to_prot) # back to protected mode
.code32
andl $0xffff, %eax
pop %edi
pop %esi
pop %edx
pop %ecx
popl %ebx
popl %ebp
ret
/*
* biosdisk_getinfo(int dev): return a word that represents the
* max number of sectors, heads and cylinders for this device
*/
ENTRY(biosdisk_getinfo)
pushl %ebp
movl %esp, %ebp
push %es
pushl %ebx
push %ecx
push %edx
push %esi
push %edi
movb 8(%ebp), %dl # diskinfo(drive #)
call _C_LABEL(prot_to_real) # enter real mode
.code16
push %dx # save drive #
movb $0x08, %ah # ask for disk info
int $0x13
pop %bx # restore drive #
jnc ok
testb $0x80, %bl # is it a hard disk?
jnz ok
/*
* Urk. Call failed. It is not supported for floppies by old BIOS's.
* Guess it's a 15-sector floppy. Initialize all the registers for
* documentation, although we only need head and sector counts.
*/
xorw %ax, %ax # set status to success
# movb %ah, %bh # %bh = 0
# movb $2, %bl # %bl bits 0-3 = drive type, 2 = 1.2M
movb $79, %ch # max track
movb $15, %cl # max sector
movb $1, %dh # max head
# movb $1, %dl # # floppy drives installed
# es:di = parameter table
# carry = 0
ok:
calll _C_LABEL(real_to_prot) # back to protected mode
.code32
/* form a longword representing all this gunk */
shrl $8, %eax # clear unnecessary bits
shll $24, %eax
shll $16, %ecx # do the same for %ecx
shrl $8, %ecx
movb %dh, %cl # max head
orl %ecx, %eax # return value in %eax
pop %edi
pop %esi
pop %edx
pop %ecx
popl %ebx
pop %es
popl %ebp
ret
/*
* int biosdisk_int13ext(int dev):
* check for availibility of int13 extensions.
*/
ENTRY(biosdisk_int13ext)
pushl %ebp
movl %esp, %ebp
pushl %ebx
pushl %ecx
pushl %edx
pushl %esi
pushl %edi
movb 8(%ebp), %dl # drive #
movw $0x55aa, %bx
call _C_LABEL(prot_to_real) # enter real mode
.code16
movb $0x41, %ah # ask for disk info
int $0x13
setnc %dl
calll _C_LABEL(real_to_prot) # switch back
.code32
xorl %eax, %eax
movb %dl, %al # return value in %ax
cmpw $0xaa55, %bx
sete %dl
andb %dl, %al
andb %cl, %al
popl %edi
popl %esi
popl %edx
popl %ecx
popl %ebx
popl %ebp
ret
/*
* BIOS call "INT 0x13 Function 0x42" to read sectors from disk into memory
* Call with %ah = 0x42
* %ds:%si = parameter block (data buffer address
* must be a real mode physical address).
* %dl = drive (0x80 for hard disk, 0x0 for floppy disk)
* Return:
* %al = 0x0 on success; err code on failure
*/
ENTRY(biosdisk_extread)
pushl %ebp
movl %esp, %ebp
pushl %ebx
push %ecx
push %edx
push %esi
push %edi
movb 8(%ebp), %dl # device
movl 12(%ebp), %esi # parameter block
call _C_LABEL(prot_to_real) # enter real mode
.code16
movl %esi, %eax
shrl $4, %eax
movw %ds, %bx
addw %bx, %ax
movw %ax, %ds
andw $0xf, %si
movb $0x42, %ah # subfunction
int $0x13
setc %bl
movb %ah, %bh # save error code
calll _C_LABEL(real_to_prot) # back to protected mode
.code32
xorl %eax, %eax
movw %bx, %ax # return value in %ax
pop %edi
pop %esi
pop %edx
pop %ecx
popl %ebx
popl %ebp
ret
ENTRY(biosdisk_getextinfo)
pushl %ebp
movl %esp, %ebp
pushl %ebx
push %ecx
push %edx
push %esi
push %edi
movb 8(%ebp), %dl # device
movl 12(%ebp), %esi # parameter block
call _C_LABEL(prot_to_real) # enter real mode
.code16
movl %esi, %eax
shrl $4, %eax
andw $0xf, %si
movw %ds, %bx
addw %bx, %ax
movw %ax, %ds
movb $0x48, %ah # subfunction
int $0x13
setc %bl
calll _C_LABEL(real_to_prot) # back to protected mode
.code32
xorl %eax, %eax
movb %bl, %al # return value in %ax
pop %edi
pop %esi
pop %edx
pop %ecx
popl %ebx
popl %ebp
ret