subr_clock.c revision 178162 
1/*-
2 * Copyright (c) 1988 University of Utah.
3 * Copyright (c) 1982, 1990, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * the Systems Programming Group of the University of Utah Computer
8 * Science Department.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 4. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 *	from: Utah $Hdr: clock.c 1.18 91/01/21$
35 *	from: @(#)clock.c	8.2 (Berkeley) 1/12/94
36 *	from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
37 *	and
38 *	from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
39 */
40
41#include <sys/cdefs.h>
42__FBSDID("$FreeBSD: head/sys/kern/subr_clock.c 178162 2008-04-12 20:35:56Z phk $");
43
44#include <sys/param.h>
45#include <sys/systm.h>
46#include <sys/kernel.h>
47#include <sys/bus.h>
48#include <sys/clock.h>
49#include <sys/sysctl.h>
50#include <sys/timetc.h>
51
52#define ct_debug bootverbose
53static int adjkerntz;		/* local offset from GMT in seconds */
54static int wall_cmos_clock;	/* wall CMOS clock assumed if != 0 */
55int disable_rtc_set;		/* disable resettodr() if != 0 */
56
57int tz_minuteswest;
58int tz_dsttime;
59
60/*
61 * These have traditionally been in machdep, but should probably be moved to
62 * kern.
63 */
64SYSCTL_INT(_machdep, OID_AUTO, disable_rtc_set,
65	CTLFLAG_RW, &disable_rtc_set, 0, "");
66
67SYSCTL_INT(_machdep, OID_AUTO, wall_cmos_clock,
68	CTLFLAG_RW, &wall_cmos_clock, 0, "");
69
70static int
71sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
72{
73	int error;
74	error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2,
75		req);
76	if (!error && req->newptr)
77		resettodr();
78	return (error);
79}
80
81SYSCTL_PROC(_machdep, OID_AUTO, adjkerntz, CTLTYPE_INT|CTLFLAG_RW,
82	&adjkerntz, 0, sysctl_machdep_adjkerntz, "I", "");
83
84/*--------------------------------------------------------------------*
85 * Generic routines to convert between a POSIX date
86 * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
87 * Derived from NetBSD arch/hp300/hp300/clock.c
88 */
89
90
91#define	FEBRUARY	2
92#define	days_in_year(y) 	(leapyear(y) ? 366 : 365)
93#define	days_in_month(y, m) \
94	(month_days[(m) - 1] + (m == FEBRUARY ? leapyear(y) : 0))
95/* Day of week. Days are counted from 1/1/1970, which was a Thursday */
96#define	day_of_week(days)	(((days) + 4) % 7)
97
98static const int month_days[12] = {
99	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
100};
101
102
103/*
104 * This inline avoids some unnecessary modulo operations
105 * as compared with the usual macro:
106 *   ( ((year % 4) == 0 &&
107 *      (year % 100) != 0) ||
108 *     ((year % 400) == 0) )
109 * It is otherwise equivalent.
110 */
111static int
112leapyear(int year)
113{
114	int rv = 0;
115
116	if ((year & 3) == 0) {
117		rv = 1;
118		if ((year % 100) == 0) {
119			rv = 0;
120			if ((year % 400) == 0)
121				rv = 1;
122		}
123	}
124	return (rv);
125}
126
127static void
128print_ct(struct clocktime *ct)
129{
130	printf("[%04d-%02d-%02d %02d:%02d:%02d]",
131	    ct->year, ct->mon, ct->day,
132	    ct->hour, ct->min, ct->sec);
133}
134
135int
136clock_ct_to_ts(struct clocktime *ct, struct timespec *ts)
137{
138	time_t secs;
139	int i, year, days;
140
141	year = ct->year;
142
143	if (ct_debug) {
144		printf("ct_to_ts(");
145		print_ct(ct);
146		printf(")");
147	}
148
149	/* Sanity checks. */
150	if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
151	    ct->day > days_in_month(year, ct->mon) ||
152	    ct->hour > 23 ||  ct->min > 59 || ct->sec > 59 ||
153	    ct->year > 2037) {		/* time_t overflow */
154		if (ct_debug)
155			printf(" = EINVAL\n");
156		return (EINVAL);
157	}
158
159	/*
160	 * Compute days since start of time
161	 * First from years, then from months.
162	 */
163	days = 0;
164	for (i = POSIX_BASE_YEAR; i < year; i++)
165		days += days_in_year(i);
166
167	/* Months */
168	for (i = 1; i < ct->mon; i++)
169	  	days += days_in_month(year, i);
170	days += (ct->day - 1);
171
172	/* XXX Dow sanity check. Dow is not used, so should we check it? */
173	if (ct->dow != -1 && ct->dow != day_of_week(days))
174		return (EINVAL);
175
176	/* Add hours, minutes, seconds. */
177	secs = ((days * 24 + ct->hour) * 60 + ct->min) * 60 + ct->sec;
178
179	ts->tv_sec = secs;
180	ts->tv_nsec = ct->nsec;
181	if (ct_debug)
182		printf(" = %d.%09ld\n", ts->tv_sec, (long)ts->tv_nsec);
183	return (0);
184}
185
186void
187clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
188{
189	int i, year, days;
190	time_t rsec;	/* remainder seconds */
191	time_t secs;
192
193	secs = ts->tv_sec;
194	days = secs / SECDAY;
195	rsec = secs % SECDAY;
196
197	ct->dow = day_of_week(days);
198
199	/* Subtract out whole years, counting them in i. */
200	for (year = POSIX_BASE_YEAR; days >= days_in_year(year); year++)
201		days -= days_in_year(year);
202	ct->year = year;
203
204	/* Subtract out whole months, counting them in i. */
205	for (i = 1; days >= days_in_month(year, i); i++)
206		days -= days_in_month(year, i);
207	ct->mon = i;
208
209	/* Days are what is left over (+1) from all that. */
210	ct->day = days + 1;
211
212	/* Hours, minutes, seconds are easy */
213	ct->hour = rsec / 3600;
214	rsec = rsec % 3600;
215	ct->min  = rsec / 60;
216	rsec = rsec % 60;
217	ct->sec  = rsec;
218	ct->nsec = ts->tv_nsec;
219	if (ct_debug) {
220		printf("ts_to_ct(%d.%09ld) = ", ts->tv_sec, (long)ts->tv_nsec);
221		print_ct(ct);
222		printf("\n");
223	}
224}
225
226int
227utc_offset(void)
228{
229
230	return (tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0));
231}
232