1ca987d46SWarner Losh /*-
2ca987d46SWarner Losh * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
3ca987d46SWarner Losh * All rights reserved.
4ca987d46SWarner Losh *
5ca987d46SWarner Losh * Redistribution and use in source and binary forms, with or without
6ca987d46SWarner Losh * modification, are permitted provided that the following conditions
7ca987d46SWarner Losh * are met:
8ca987d46SWarner Losh * 1. Redistributions of source code must retain the above copyright
9ca987d46SWarner Losh * notice, this list of conditions and the following disclaimer.
10ca987d46SWarner Losh * 2. Redistributions in binary form must reproduce the above copyright
11ca987d46SWarner Losh * notice, this list of conditions and the following disclaimer in the
12ca987d46SWarner Losh * documentation and/or other materials provided with the distribution.
13ca987d46SWarner Losh *
14ca987d46SWarner Losh * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15ca987d46SWarner Losh * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16ca987d46SWarner Losh * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17ca987d46SWarner Losh * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18ca987d46SWarner Losh * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19ca987d46SWarner Losh * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20ca987d46SWarner Losh * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21ca987d46SWarner Losh * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22ca987d46SWarner Losh * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23ca987d46SWarner Losh * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24ca987d46SWarner Losh * SUCH DAMAGE.
25ca987d46SWarner Losh */
26ca987d46SWarner Losh
27ca987d46SWarner Losh #include <stand.h>
28ca987d46SWarner Losh #include <btxv86.h>
29ca987d46SWarner Losh #include "bootstrap.h"
30ca987d46SWarner Losh #include "libi386.h"
31ca987d46SWarner Losh
32ca987d46SWarner Losh time_t getsecs(void);
33ca987d46SWarner Losh static int bios_seconds(void);
34ca987d46SWarner Losh
35ca987d46SWarner Losh /*
36ca987d46SWarner Losh * Return the BIOS time-of-day value.
37ca987d46SWarner Losh *
38bd001d86SWarner Losh * XXX uses undocumented BCD support from libsa.
39ca987d46SWarner Losh */
40ca987d46SWarner Losh static int
bios_seconds(void)41ca987d46SWarner Losh bios_seconds(void)
42ca987d46SWarner Losh {
43ca987d46SWarner Losh int hr, minute, sec;
44ca987d46SWarner Losh
45ca987d46SWarner Losh v86.ctl = 0;
46ca987d46SWarner Losh v86.addr = 0x1a; /* int 0x1a, function 2 */
47ca987d46SWarner Losh v86.eax = 0x0200;
48ca987d46SWarner Losh v86int();
49ca987d46SWarner Losh
50ca987d46SWarner Losh hr = bcd2bin((v86.ecx & 0xff00) >> 8); /* hour in %ch */
51ca987d46SWarner Losh minute = bcd2bin(v86.ecx & 0xff); /* minute in %cl */
52ca987d46SWarner Losh sec = bcd2bin((v86.edx & 0xff00) >> 8); /* second in %dh */
53ca987d46SWarner Losh
54ca987d46SWarner Losh return (hr * 3600 + minute * 60 + sec);
55ca987d46SWarner Losh }
56ca987d46SWarner Losh
57ca987d46SWarner Losh /*
58ca987d46SWarner Losh * Return the time in seconds since the beginning of the day.
59ca987d46SWarner Losh *
60ca987d46SWarner Losh * Some BIOSes (notably qemu) don't correctly read the RTC
61ca987d46SWarner Losh * registers in an atomic way, sometimes returning bogus values.
62ca987d46SWarner Losh * Therefore we "debounce" the reading by accepting it only when
63ca987d46SWarner Losh * we got 8 identical values in succession.
64ca987d46SWarner Losh *
65ca987d46SWarner Losh * If we pass midnight, don't wrap back to 0.
66ca987d46SWarner Losh */
67ca987d46SWarner Losh time_t
time(time_t * t)68ca987d46SWarner Losh time(time_t *t)
69ca987d46SWarner Losh {
70ca987d46SWarner Losh static time_t lasttime;
71ca987d46SWarner Losh time_t now, check;
72ca987d46SWarner Losh int same, try;
73ca987d46SWarner Losh
74ca987d46SWarner Losh same = try = 0;
75ca987d46SWarner Losh check = bios_seconds();
76ca987d46SWarner Losh do {
77ca987d46SWarner Losh now = check;
78ca987d46SWarner Losh check = bios_seconds();
79ca987d46SWarner Losh if (check != now)
80ca987d46SWarner Losh same = 0;
81ca987d46SWarner Losh } while (++same < 8 && ++try < 1000);
82ca987d46SWarner Losh
83ca987d46SWarner Losh if (now < lasttime)
84ca987d46SWarner Losh now += 24 * 3600;
85ca987d46SWarner Losh lasttime = now;
86ca987d46SWarner Losh
87ca987d46SWarner Losh if (t != NULL)
88ca987d46SWarner Losh *t = now;
89ca987d46SWarner Losh return(now);
90ca987d46SWarner Losh }
91ca987d46SWarner Losh
92ca987d46SWarner Losh time_t
getsecs(void)93ca987d46SWarner Losh getsecs(void)
94ca987d46SWarner Losh {
95ca987d46SWarner Losh time_t n = 0;
96ca987d46SWarner Losh time(&n);
97ca987d46SWarner Losh return n;
98ca987d46SWarner Losh }
99ca987d46SWarner Losh
100ca987d46SWarner Losh /*
101ca987d46SWarner Losh * Use the BIOS Wait function to pause for (period) microseconds.
102ca987d46SWarner Losh *
103ca987d46SWarner Losh * Resolution of this function is variable, but typically around
104ca987d46SWarner Losh * 1ms.
105ca987d46SWarner Losh */
106ca987d46SWarner Losh void
delay(int period)107ca987d46SWarner Losh delay(int period)
108ca987d46SWarner Losh {
109ca987d46SWarner Losh v86.ctl = 0;
110ca987d46SWarner Losh v86.addr = 0x15; /* int 0x15, function 0x86 */
111ca987d46SWarner Losh v86.eax = 0x8600;
112ca987d46SWarner Losh v86.ecx = period >> 16;
113ca987d46SWarner Losh v86.edx = period & 0xffff;
114ca987d46SWarner Losh v86int();
115ca987d46SWarner Losh }
116