1/*-
2 * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <stand.h>
28#include <btxv86.h>
29#include "bootstrap.h"
30#include "libi386.h"
31
32time_t		getsecs(void);
33static int	bios_seconds(void);
34
35/*
36 * Return the BIOS time-of-day value.
37 *
38 * XXX uses undocumented BCD support from libsa.
39 */
40static int
41bios_seconds(void)
42{
43    int			hr, minute, sec;
44
45    v86.ctl = 0;
46    v86.addr = 0x1a;		/* int 0x1a, function 2 */
47    v86.eax = 0x0200;
48    v86int();
49
50    hr = bcd2bin((v86.ecx & 0xff00) >> 8);	/* hour in %ch */
51    minute = bcd2bin(v86.ecx & 0xff);		/* minute in %cl */
52    sec = bcd2bin((v86.edx & 0xff00) >> 8);	/* second in %dh */
53
54    return (hr * 3600 + minute * 60 + sec);
55}
56
57/*
58 * Return the time in seconds since the beginning of the day.
59 *
60 * Some BIOSes (notably qemu) don't correctly read the RTC
61 * registers in an atomic way, sometimes returning bogus values.
62 * Therefore we "debounce" the reading by accepting it only when
63 * we got 8 identical values in succession.
64 *
65 * If we pass midnight, don't wrap back to 0.
66 */
67time_t
68time(time_t *t)
69{
70    static time_t lasttime;
71    time_t now, check;
72    int same, try;
73
74    same = try = 0;
75    check = bios_seconds();
76    do {
77	now = check;
78	check = bios_seconds();
79	if (check != now)
80	    same = 0;
81    } while (++same < 8 && ++try < 1000);
82
83    if (now < lasttime)
84	now += 24 * 3600;
85    lasttime = now;
86
87    if (t != NULL)
88	*t = now;
89    return(now);
90}
91
92time_t
93getsecs(void)
94{
95	time_t n = 0;
96	time(&n);
97	return n;
98}
99
100/*
101 * Use the BIOS Wait function to pause for (period) microseconds.
102 *
103 * Resolution of this function is variable, but typically around
104 * 1ms.
105 */
106void
107delay(int period)
108{
109    v86.ctl = 0;
110    v86.addr = 0x15;		/* int 0x15, function 0x86 */
111    v86.eax = 0x8600;
112    v86.ecx = period >> 16;
113    v86.edx = period & 0xffff;
114    v86int();
115}
116