disk.s revision 64660 
1# Copyright (c) KATO Takenori, 1999, 2000.
2#
3# All rights reserved.  Unpublished rights reserved under the copyright
4# laws of Japan.
5#
6# Redistribution and use in source and binary forms, with or without
7# modification, are permitted provided that the following conditions
8# are met:
9#
10# 1. Redistributions of source code must retain the above copyright
11#    notice, this list of conditions and the following disclaimer as
12#    the first lines of this file unmodified.
13# 2. Redistributions in binary form must reproduce the above copyright
14#    notice, this list of conditions and the following disclaimer in the
15#    documentation and/or other materials provided with the distribution.
16#
17# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27#
28# $FreeBSD: head/sys/boot/pc98/boot0.5/disk.s 64660 2000-08-15 08:17:03Z kato $
29#
30
31	.code16
32	.text
33#
34# Check magic number at the end of the sector 0
35#
36check_magic:
37	movw	curdevice, %si
38	shlw	%si
39	movw	secsize(%si), %bx
40	decw	%bx
41	decw	%bx
42	movw	iplbuf(%bx), %ax
43	cmpw	$0xaa55, %ax
44	je	magic_ok
45	movw	$1, %ax
46	ret
47magic_ok:
48	xorw	%ax, %ax
49	ret
50
51#
52# Copy partition table from buffer to parttable.
53#
54setup_partition:
55	push	%cs
56	pop	%es
57	movw	curdevice, %bx
58	shlw	%bx
59	movw	maxpart(%bx), %cx	# %cx = max num of partitions
60	movw	partoff(%bx), %di
61	movw	%di, %bx		# %bx = offset to partition table
62	xorw	%dx, %dx		# %dx = partition number
63setup_partition_loop:
64	push	%cx
65	movw	%dx, %si
66	movb	$5, %cl
67	shlw	%cl, %si
68	addw	%bx, %si
69	movb	iplbuf(%si), %al
70	orb	%al, %al
71	jz	unused_partition
72	addw	$iplbuf, %si
73	movw	npartition, %ax
74	movw	%ax, %di
75	movb	$5, %cl
76	shlw	%cl, %di
77	addw	$parttable, %di
78	movw	$32, %cx
79	rep
80	movsb
81	movw	%ax, %di
82	addw	$partnum, %di
83	movb	%dl, (%di)
84	incw	npartition
85unused_partition:
86	incw	%dx
87	pop	%cx
88	loop	setup_partition_loop
89	ret
90
91#
92# Read IPL and partition table in the current device.
93#
94	.global	read_ipl
95read_ipl:
96	movw	curdevice, %ax
97	movw	%ax, %si		# %si = device number
98	movw	%ax, %di
99	shlw	%di
100
101	movw	%cs, %ax
102	movw	%ax, %es
103	movb	$6, %ah
104	movb	daua(%si), %al
105	movw	$0x400, %bx
106	xorw	%cx, %cx
107	xorw	%dx, %dx
108	movw	$iplbuf, %bp
109	int	$0x1b
110	jc	read_ipl_error
111	movw	defflagoff(%di), %bx
112	movb	iplbuf(%bx), %al
113	movb	%al, defpartflag
114	incw	%bx
115	movb	iplbuf(%bx), %al
116	movb	%al, defpartnum
117	movw	$0, npartition
118	call	check_magic
119	orw	%ax, %ax
120	jnz	no_magic
121	call	setup_partition
122no_magic:
123	xorw	%ax, %ax
124read_ipl_error:
125	xorw	%bx, %bx
126	movw	%bx, %es
127	ret
128
129#
130# Restore IPL from the buffer
131#
132	.global	write_ipl
133write_ipl:
134	movw	curdevice, %ax
135	movw	%ax, %si
136	movw	%ax, %di
137	shlw	%di
138
139	# Restore default boot partition info.
140	movw	defflagoff(%di), %bx
141	movb	defpartflag, %al
142	movb	%al, iplbuf(%bx)
143	incw	%bx
144	movb	defpartnum, %al
145	movb	%al, iplbuf(%bx)
146
147	movw	%cs, %ax
148	movw	%ax, %es
149	movb	$5, %ah
150	movb	daua(%si), %al
151	movw	secsize(%di), %bx
152	xorw	%cx, %cx
153	xorw	%dx, %dx
154	movw	$iplbuf, %bp
155	int	$0x1b
156	jc	write_ipl_error
157	xorw	%ax, %ax
158write_ipl_error:
159	xorw	%bx, %bx
160	movw	%bx, %es
161	ret
162
163#
164# Scan HDD devices
165#
166	.global	scan_sasi, scan_scsi
167	# Scan SASI disk
168scan_sasi:
169	# SASI Disk
170	movw	$4, %cx
171	movw	$0x0001, %ax	# %ah =  unit number, %al = for bit operation
172
173sasi_loop:
174	movw	%si, %di
175	shlw	%di
176	movw	$0x55d, %bx		# DISK_EQUIP
177	call	read_biosparam
178	testb	%al, %dl
179	jz	no_sasi_unit
180	movb	$0x80, %dh
181	addb	%ah, %dh
182	movb	%dh, daua(%si)
183	movw	$0x457, %bx		# capacity & sector size of IDE HDD
184	call	read_biosparam
185	orb	%ah, %ah
186	jz	sasi_1
187	cmpb	$1, %ah
188	jz	sasi_2
189
190	# SASI #3/#4
191	movw	$512, %dx		# XXX
192	jmp	found_sasi_unit
193
194sasi_1:
195	# SASI #1
196	testb	$0x80, %dl
197	jz	sasi_256
198	jmp	sasi_512
199sasi_2:
200	# SASI #2
201	testb	$0x40, %dl
202	jz	sasi_256
203	jmp	sasi_512
204
205sasi_256:
206	movw	$256, %dx
207	jmp	found_sasi_unit
208sasi_512:
209	movw	$512, %dx
210found_sasi_unit:
211	movw	%dx, secsize(%di)
212	incw	%si
213no_sasi_unit:
214	incb	%ah
215	shlb	%al
216	loop	sasi_loop
217	ret
218
219#
220# Scan SCSI disk
221#	SI	number of disks
222#	destroyed: %ax, %bx, %cx, %dx
223scan_scsi:
224	movw	$8, %cx
225	movw	$0x0001, %ax	# %ah = ID number, %al = for bit operation
226scsi_loop:
227	# Check whether drive exist.
228	movw	%si, %di
229	shlw	%di
230	movw	$0x482, %bx		# DISK_EQUIPS
231	call	read_biosparam
232	testb	%al, %dl
233	jz	no_scsi_unit
234	xorw	%bx, %bx
235	movb	%ah, %bl
236	shlw	%bx
237	shlw	%bx
238	addw	$0x460, %bx		# SCSI paramter block
239	call	read_biosparam
240	orb	%dl, %dl
241	jz	no_scsi_unit
242
243	# SCSI harddrive found.
244	movb	$0xa0, %dh
245	addb	%ah, %dh
246	movb	%dh, daua(%si)
247
248	# Check sector size.
249	addw	$3, %bx
250	call	read_biosparam
251	andb	$0x30, %dl
252	cmpb	$0x20, %dl
253	je	scsi_1024
254	cmpb	$0x10, %dl
255	je	scsi_512
256	movw	$256, %dx
257	jmp	found_scsi
258scsi_1024:
259	movw	$1024, %dx
260	jmp	found_scsi
261scsi_512:
262	movw	$512, %dx
263found_scsi:
264	movw	%dx, secsize(%di)
265	incw	%si
266no_scsi_unit:
267	incb	%ah
268	shlb	%al
269	loop	scsi_loop
270	ret
271
272	.data
273	.global	partnum, parttable, defpartflag, defpartnum, npartition
274partnum:	.space	32		# Index of parttable
275parttable:	.space	1024		# Copy of valid partition table
276defpartflag:	.byte	0
277defpartnum:	.byte	0
278npartition:	.word	0		# number of partitions
279	.bss
280iplbuf:		.space	0x400
281