1/*        $NetBSD: bios_disk.S,v 1.23 2022/09/10 12:14:17 rillig 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/boot/bios.S */
55
56#include <machine/asm.h>
57
58/*
59 * BIOS call "INT 0x13 Function 0x0" to reset the disk subsystem
60 *        Call with %ah = 0x0
61 *                            %dl = drive (0x80 for hard disk, 0x0 for floppy disk)
62 *        Return:
63 *                            %al = 0x0 on success; err code on failure
64 */
65ENTRY(biosdisk_reset)
66          pusha
67
68          movb      %al, %dl  # device
69
70          call      _C_LABEL(prot_to_real)        # enter real mode
71          .code16
72
73          movb      $0x0, %ah # subfunction
74          int       $0x13
75          setc      %bl
76          movb      %ah, %bh  # save error code
77
78          calll     _C_LABEL(real_to_prot) # back to protected mode
79          .code32
80
81          movzwl    %bx, %eax # return value in %eax
82          movl      %eax, 28(%esp)
83
84          popa
85          ret
86
87/*
88 * BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory
89 *        Call with %ah = 0x2
90 *                            %al = number of sectors
91 *                            %ch = cylinder
92 *                            %cl = sector
93 *                            %dh = head
94 *                            %dl = drive (0x80 for hard disk, 0x0 for floppy disk)
95 *                            %es:%bx = segment:offset of buffer
96 *        Return:
97 *                            %al = 0x0 on success; err code on failure
98 *
99 * biosdisk_read(dev, cyl, head, sect, count, buff_addr);
100 *
101 *  Note: On failure, you must reset the disk with biosdisk_reset() before
102 *        sending another command.
103 */
104ENTRY(biosdisk_read)
105          pusha
106
107          movb      44(%esp), %dh
108          movw      40(%esp), %cx
109          xchgb     %ch, %cl  # cylinder; the highest 2 bits of cyl is in %cl
110          rorb      $2, %cl
111          movb      48(%esp), %al
112          orb       %al, %cl
113          incb      %cl                 # sector; sec starts from 1, not 0
114          movb      36(%esp), %dl       # device
115          movl      56(%esp), %ebx      # buffer address (may be >64k)
116          movb      52(%esp), %al       # number of sectors
117
118          call      _C_LABEL(prot_to_real)        # enter real mode
119          .code16
120
121          push      %bx
122          shrl      $4, %ebx  # max segment
123          mov       %ds, %si
124          add       %si, %bx
125          mov       %bx, %es  # %es:%bx now valid buffer address
126          pop       %bx
127          and       $0xf, %bx # and min offset - to avoid overrun
128
129          movb      $0x2, %ah # subfunction
130          int       $0x13
131          setc      %al                 # error code is in %ah
132
133          calll     _C_LABEL(real_to_prot) # back to protected mode
134          .code32
135
136          andl    $0x0000FFFF, %eax  # Some bioses set high bits in %eax
137                                     #  on success, interfering with our
138                                     #  return value.  Clear those out.
139          movl      %eax, 28(%esp)
140
141          popa
142          ret
143
144/*
145 * biosdisk_getinfo(int dev):  return a word that represents the
146 *        max number of sectors, heads and cylinders for this device
147 */
148ENTRY(biosdisk_getinfo)
149          push      %es
150          pusha
151
152          movb      %al, %dl            # diskinfo(drive #)
153
154          call      _C_LABEL(prot_to_real)        # enter real mode
155          .code16
156
157          push      %dx                           # save drive #
158          movb      $0x08, %ah                    # ask for disk info
159          int       $0x13
160          pop       %bx                           # restore drive #
161          jnc       ok
162
163          testb     $0x80, %bl                    # is it a hard disk?
164          jnz       ok
165
166          /*
167           * Urk.  Call failed.  It is not supported for floppies by old BIOS's.
168           * Guess it's a 15-sector floppy.  Initialize all the registers for
169           * documentation, although we only need head and sector counts.
170           */
171          xorw      %ax, %ax            # set status to success
172#         movb      %ah, %bh            # %bh = 0
173#         movb      $2, %bl                       # %bl bits 0-3 = drive type, 2 = 1.2M
174          movb      $79, %ch            # max track
175          movb      $15, %cl            # max sector
176          movb      $1, %dh                       # max head
177#         movb      $1, %dl                       # # floppy drives installed
178          # es:di = parameter table
179          # carry = 0
180
181ok:
182          calll     _C_LABEL(real_to_prot)        # back to protected mode
183          .code32
184
185          /* form a longword representing all this gunk */
186          shrl      $8, %eax            # clear unnecessary bits
187          shll      $24, %eax
188          shll      $16, %ecx           # do the same for %ecx
189          shrl      $8, %ecx
190          movb      %dh, %cl            # max head
191          orl       %ecx, %eax                    # return value in %eax
192          movl      %eax, 28(%esp)
193
194          popa
195          pop       %es
196          ret
197
198/*
199 * int biosdisk_int13ext(int dev):
200 *        check for availability of int13 extensions.
201 */
202ENTRY(biosdisk_int13ext)
203          pusha
204
205          movb      %al, %dl            # drive #
206          movw      $0x55aa, %bx
207
208          call      _C_LABEL(prot_to_real)        # enter real mode
209          .code16
210
211          movb      $0x41, %ah                    # ask for disk info
212          int       $0x13
213          setnc     %dl
214
215          calll     _C_LABEL(real_to_prot)        # switch back
216          .code32
217
218          movzbl    %dl, %eax           # return value in %eax
219
220          cmpw      $0xaa55, %bx
221          sete      %dl
222          andb      %dl, %al
223
224          andb      %cl, %al
225          movl      %eax, 28(%esp)
226
227          popa
228          ret
229
230/*
231 * BIOS call "INT 0x13 Function 0x42" to read sectors from disk into memory
232 *        Call with %ah = 0x42
233 *                            %ds:%si = parameter block (data buffer address
234 *                                      must be a real mode physical address).
235 *                            %dl = drive (0x80 for hard disk, 0x0 for floppy disk)
236 *        Return:
237 *                            %al = 0x0 on success; err code on failure
238 */
239ENTRY(biosdisk_extread)
240          pusha
241
242          movl      %edx, %esi          # parameter block
243          movb      %al, %dl  # device
244
245          call      _C_LABEL(prot_to_real)        # enter real mode
246          .code16
247
248          push      %ds
249          movl      %esi, %eax
250          shrl      $4, %eax
251          movw      %ds, %bx
252          addw      %bx, %ax
253          movw      %ax, %ds
254          andw      $0xf, %si
255
256          movb      $0x42, %ah          # subfunction
257          int       $0x13
258          setc      %bl
259          movb      %ah, %bh  # save error code
260          pop       %ds
261
262          calll     _C_LABEL(real_to_prot) # back to protected mode
263          .code32
264
265          movzwl    %bx, %eax # return value in %eax
266          movl      %eax, 28(%esp)
267
268          popa
269          ret
270
271ENTRY(biosdisk_getextinfo)
272          pusha
273
274          movl      %edx, %esi          # parameter block
275          movb      %al, %dl  # device
276
277          call      _C_LABEL(prot_to_real)        # enter real mode
278          .code16
279
280          push      %ds
281          movl      %esi, %eax
282          shrl      $4, %eax
283          andw      $0xf, %si
284          movw      %ds, %bx
285          addw      %bx, %ax
286          movw      %ax, %ds
287
288          movb      $0x48, %ah          # subfunction
289          int       $0x13
290          setc      %bl
291          pop       %ds
292
293          calll     _C_LABEL(real_to_prot) # back to protected mode
294          .code32
295
296          movzbl    %bl, %eax # return value in %eax
297          movl      %eax, 28(%esp)
298
299          popa
300          ret
301