FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_clock.c
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("$FreeBSD$");
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 static int adjkerntz; /* local offset from GMT in seconds */
53 static int wall_cmos_clock; /* wall CMOS clock assumed if != 0 */
54 int disable_rtc_set; /* disable resettodr() if != 0 */
55
56 int tz_minuteswest;
57 int tz_dsttime;
58
59 /*
60 * These have traditionally been in machdep, but should probably be moved to
61 * kern.
62 */
63 SYSCTL_INT(_machdep, OID_AUTO, disable_rtc_set,
64 CTLFLAG_RW, &disable_rtc_set, 0, "");
65
66 SYSCTL_INT(_machdep, OID_AUTO, wall_cmos_clock,
67 CTLFLAG_RW, &wall_cmos_clock, 0, "");
68
69 static int
70 sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
71 {
72 int error;
73 error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2,
74 req);
75 if (!error && req->newptr)
76 resettodr();
77 return (error);
78 }
79
80 SYSCTL_PROC(_machdep, OID_AUTO, adjkerntz, CTLTYPE_INT|CTLFLAG_RW,
81 &adjkerntz, 0, sysctl_machdep_adjkerntz, "I", "");
82
83 /*--------------------------------------------------------------------*
84 * Generic routines to convert between a POSIX date
85 * (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
86 * Derived from NetBSD arch/hp300/hp300/clock.c
87 */
88
89
90 #define FEBRUARY 2
91 #define days_in_year(y) (leapyear(y) ? 366 : 365)
92 #define days_in_month(y, m) \
93 (month_days[(m) - 1] + (m == FEBRUARY ? leapyear(y) : 0))
94 /* Day of week. Days are counted from 1/1/1970, which was a Thursday */
95 #define day_of_week(days) (((days) + 4) % 7)
96
97 static const int month_days[12] = {
98 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
99 };
100
101
102 /*
103 * This inline avoids some unnecessary modulo operations
104 * as compared with the usual macro:
105 * ( ((year % 4) == 0 &&
106 * (year % 100) != 0) ||
107 * ((year % 400) == 0) )
108 * It is otherwise equivalent.
109 */
110 static __inline int
111 leapyear(int year)
112 {
113 int rv = 0;
114
115 if ((year & 3) == 0) {
116 rv = 1;
117 if ((year % 100) == 0) {
118 rv = 0;
119 if ((year % 400) == 0)
120 rv = 1;
121 }
122 }
123 return (rv);
124 }
125
126 int
127 clock_ct_to_ts(struct clocktime *ct, struct timespec *ts)
128 {
129 time_t secs;
130 int i, year, days;
131
132 year = ct->year;
133
134 /* Sanity checks. */
135 if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
136 ct->day > days_in_month(year, ct->mon) ||
137 ct->hour > 23 || ct->min > 59 || ct->sec > 59 ||
138 ct->year > 2037) /* time_t overflow */
139 return (EINVAL);
140
141 /*
142 * Compute days since start of time
143 * First from years, then from months.
144 */
145 days = 0;
146 for (i = POSIX_BASE_YEAR; i < year; i++)
147 days += days_in_year(i);
148
149 /* Months */
150 for (i = 1; i < ct->mon; i++)
151 days += days_in_month(year, i);
152 days += (ct->day - 1);
153
154 /* XXX Dow sanity check. Dow is not used, so should we check it? */
155 if (ct->dow != -1 && ct->dow != day_of_week(days))
156 return (EINVAL);
157
158 /* Add hours, minutes, seconds. */
159 secs = ((days * 24 + ct->hour) * 60 + ct->min) * 60 + ct->sec;
160
161 ts->tv_sec = secs;
162 ts->tv_nsec = ct->nsec;
163 return (0);
164 }
165
166 void
167 clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
168 {
169 int i, year, days;
170 time_t rsec; /* remainder seconds */
171 time_t secs;
172
173 secs = ts->tv_sec;
174 days = secs / SECDAY;
175 rsec = secs % SECDAY;
176
177 ct->dow = day_of_week(days);
178
179 /* Subtract out whole years, counting them in i. */
180 for (year = POSIX_BASE_YEAR; days >= days_in_year(year); year++)
181 days -= days_in_year(year);
182 ct->year = year;
183
184 /* Subtract out whole months, counting them in i. */
185 for (i = 1; days >= days_in_month(year, i); i++)
186 days -= days_in_month(year, i);
187 ct->mon = i;
188
189 /* Days are what is left over (+1) from all that. */
190 ct->day = days + 1;
191
192 /* Hours, minutes, seconds are easy */
193 ct->hour = rsec / 3600;
194 rsec = rsec % 3600;
195 ct->min = rsec / 60;
196 rsec = rsec % 60;
197 ct->sec = rsec;
198 ct->nsec = ts->tv_nsec;
199 }
200
201 int
202 utc_offset(void)
203 {
204
205 return (tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0));
206 }
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