subr_clock.c revision 215283 
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 215283 2010-11-14 08:06:29Z brucec $");
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 UTC in seconds */
54static int wall_cmos_clock;	/* wall CMOS clock assumed if != 0 */
55
56int tz_minuteswest;
57int tz_dsttime;
58
59/*
60 * This have traditionally been in machdep, but should probably be moved to
61 * kern.
62 */
63SYSCTL_INT(_machdep, OID_AUTO, wall_cmos_clock,
64	CTLFLAG_RW, &wall_cmos_clock, 0, "CMOS clock keeps wall time");
65
66static int
67sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
68{
69	int error;
70	error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
71	if (!error && req->newptr)
72		resettodr();
73	return (error);
74}
75
76SYSCTL_PROC(_machdep, OID_AUTO, adjkerntz, CTLTYPE_INT|CTLFLAG_RW,
77	&adjkerntz, 0, sysctl_machdep_adjkerntz, "I",
78	"Local offset from UTC in seconds");
79
80/*--------------------------------------------------------------------*
81 * Generic routines to convert between a POSIX date
82 * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
83 * Derived from NetBSD arch/hp300/hp300/clock.c
84 */
85
86
87#define	FEBRUARY	2
88#define	days_in_year(y) 	(leapyear(y) ? 366 : 365)
89#define	days_in_month(y, m) \
90	(month_days[(m) - 1] + (m == FEBRUARY ? leapyear(y) : 0))
91/* Day of week. Days are counted from 1/1/1970, which was a Thursday */
92#define	day_of_week(days)	(((days) + 4) % 7)
93
94static const int month_days[12] = {
95	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
96};
97
98
99/*
100 * This inline avoids some unnecessary modulo operations
101 * as compared with the usual macro:
102 *   ( ((year % 4) == 0 &&
103 *      (year % 100) != 0) ||
104 *     ((year % 400) == 0) )
105 * It is otherwise equivalent.
106 */
107static int
108leapyear(int year)
109{
110	int rv = 0;
111
112	if ((year & 3) == 0) {
113		rv = 1;
114		if ((year % 100) == 0) {
115			rv = 0;
116			if ((year % 400) == 0)
117				rv = 1;
118		}
119	}
120	return (rv);
121}
122
123static void
124print_ct(struct clocktime *ct)
125{
126	printf("[%04d-%02d-%02d %02d:%02d:%02d]",
127	    ct->year, ct->mon, ct->day,
128	    ct->hour, ct->min, ct->sec);
129}
130
131int
132clock_ct_to_ts(struct clocktime *ct, struct timespec *ts)
133{
134	time_t secs;
135	int i, year, days;
136
137	year = ct->year;
138
139	if (ct_debug) {
140		printf("ct_to_ts(");
141		print_ct(ct);
142		printf(")");
143	}
144
145	/* Sanity checks. */
146	if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
147	    ct->day > days_in_month(year, ct->mon) ||
148	    ct->hour > 23 ||  ct->min > 59 || ct->sec > 59 ||
149	    ct->year > 2037) {		/* time_t overflow */
150		if (ct_debug)
151			printf(" = EINVAL\n");
152		return (EINVAL);
153	}
154
155	/*
156	 * Compute days since start of time
157	 * First from years, then from months.
158	 */
159	days = 0;
160	for (i = POSIX_BASE_YEAR; i < year; i++)
161		days += days_in_year(i);
162
163	/* Months */
164	for (i = 1; i < ct->mon; i++)
165	  	days += days_in_month(year, i);
166	days += (ct->day - 1);
167
168	/* Add hours, minutes, seconds. */
169	secs = ((days * 24 + ct->hour) * 60 + ct->min) * 60 + ct->sec;
170
171	ts->tv_sec = secs;
172	ts->tv_nsec = ct->nsec;
173	if (ct_debug)
174		printf(" = %ld.%09ld\n", (long)ts->tv_sec, (long)ts->tv_nsec);
175	return (0);
176}
177
178void
179clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
180{
181	int i, year, days;
182	time_t rsec;	/* remainder seconds */
183	time_t secs;
184
185	secs = ts->tv_sec;
186	days = secs / SECDAY;
187	rsec = secs % SECDAY;
188
189	ct->dow = day_of_week(days);
190
191	/* Subtract out whole years, counting them in i. */
192	for (year = POSIX_BASE_YEAR; days >= days_in_year(year); year++)
193		days -= days_in_year(year);
194	ct->year = year;
195
196	/* Subtract out whole months, counting them in i. */
197	for (i = 1; days >= days_in_month(year, i); i++)
198		days -= days_in_month(year, i);
199	ct->mon = i;
200
201	/* Days are what is left over (+1) from all that. */
202	ct->day = days + 1;
203
204	/* Hours, minutes, seconds are easy */
205	ct->hour = rsec / 3600;
206	rsec = rsec % 3600;
207	ct->min  = rsec / 60;
208	rsec = rsec % 60;
209	ct->sec  = rsec;
210	ct->nsec = ts->tv_nsec;
211	if (ct_debug) {
212		printf("ts_to_ct(%ld.%09ld) = ",
213		    (long)ts->tv_sec, (long)ts->tv_nsec);
214		print_ct(ct);
215		printf("\n");
216	}
217}
218
219int
220utc_offset(void)
221{
222
223	return (tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0));
224}
225