freebsd-dev/sys/kern/subr_clock.c
Ian Lepore f1b21e2c92 Add common code to support realtime clocks that store year without century.
Most realtime clocks store the year as 2 BCD digits.  Some add a century bit
to extend the range another hundred years.  Every clock driver has its own
code to determine the century and pass a full year value to clock_ct_to_ts().
Now clock drivers can just convert BCD to bin and store the result in the
clocktime struct and let the common code figure out the century.  Clocks
with a century bit can just add 100 to year if the century bit is on.
2017-07-23 21:28:00 +00:00

267 lines
7.5 KiB
C

/*-
* Copyright (c) 1988 University of Utah.
* Copyright (c) 1982, 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: Utah $Hdr: clock.c 1.18 91/01/21$
* from: @(#)clock.c 8.2 (Berkeley) 1/12/94
* from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
* and
* from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/bus.h>
#include <sys/clock.h>
#include <sys/limits.h>
#include <sys/sysctl.h>
#include <sys/timetc.h>
int tz_minuteswest;
int tz_dsttime;
/*
* The adjkerntz and wall_cmos_clock sysctls are in the "machdep" sysctl
* namespace because they were misplaced there originally.
*/
static int adjkerntz;
static int
sysctl_machdep_adjkerntz(SYSCTL_HANDLER_ARGS)
{
int error;
error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
if (!error && req->newptr)
resettodr();
return (error);
}
SYSCTL_PROC(_machdep, OID_AUTO, adjkerntz, CTLTYPE_INT | CTLFLAG_RW |
CTLFLAG_MPSAFE, &adjkerntz, 0, sysctl_machdep_adjkerntz, "I",
"Local offset from UTC in seconds");
static int ct_debug;
SYSCTL_INT(_debug, OID_AUTO, clocktime, CTLFLAG_RWTUN,
&ct_debug, 0, "Enable printing of clocktime debugging");
static int wall_cmos_clock;
SYSCTL_INT(_machdep, OID_AUTO, wall_cmos_clock, CTLFLAG_RW,
&wall_cmos_clock, 0, "Enables application of machdep.adjkerntz");
/*--------------------------------------------------------------------*
* Generic routines to convert between a POSIX date
* (seconds since 1/1/1970) and yr/mo/day/hr/min/sec
* Derived from NetBSD arch/hp300/hp300/clock.c
*/
#define FEBRUARY 2
#define days_in_year(y) (leapyear(y) ? 366 : 365)
#define days_in_month(y, m) \
(month_days[(m) - 1] + (m == FEBRUARY ? leapyear(y) : 0))
/* Day of week. Days are counted from 1/1/1970, which was a Thursday */
#define day_of_week(days) (((days) + 4) % 7)
static const int month_days[12] = {
31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
/*
* Optimization: using a precomputed count of days between POSIX_BASE_YEAR and
* some recent year avoids lots of unnecessary loop iterations in conversion.
* recent_base_days is the number of days before the start of recent_base_year.
*/
static const int recent_base_year = 2017;
static const int recent_base_days = 17167;
/*
* This inline avoids some unnecessary modulo operations
* as compared with the usual macro:
* ( ((year % 4) == 0 &&
* (year % 100) != 0) ||
* ((year % 400) == 0) )
* It is otherwise equivalent.
*/
static int
leapyear(int year)
{
int rv = 0;
if ((year & 3) == 0) {
rv = 1;
if ((year % 100) == 0) {
rv = 0;
if ((year % 400) == 0)
rv = 1;
}
}
return (rv);
}
static void
print_ct(struct clocktime *ct)
{
printf("[%04d-%02d-%02d %02d:%02d:%02d]",
ct->year, ct->mon, ct->day,
ct->hour, ct->min, ct->sec);
}
int
clock_ct_to_ts(struct clocktime *ct, struct timespec *ts)
{
int i, year, days;
if (ct_debug) {
printf("ct_to_ts(");
print_ct(ct);
printf(")");
}
/*
* Many realtime clocks store the year as 2-digit BCD; pivot on 70 to
* determine century. Some clocks have a "century bit" and drivers do
* year += 100, so interpret values between 70-199 as relative to 1900.
*/
year = ct->year;
if (year < 70)
year += 2000;
else if (year < 200)
year += 1900;
/* Sanity checks. */
if (ct->mon < 1 || ct->mon > 12 || ct->day < 1 ||
ct->day > days_in_month(year, ct->mon) ||
ct->hour > 23 || ct->min > 59 || ct->sec > 59 || year < 1970 ||
(sizeof(time_t) == 4 && year > 2037)) { /* time_t overflow */
if (ct_debug)
printf(" = EINVAL\n");
return (EINVAL);
}
/*
* Compute days since start of time
* First from years, then from months.
*/
if (year >= recent_base_year) {
i = recent_base_year;
days = recent_base_days;
} else {
i = POSIX_BASE_YEAR;
days = 0;
}
for (; i < year; i++)
days += days_in_year(i);
/* Months */
for (i = 1; i < ct->mon; i++)
days += days_in_month(year, i);
days += (ct->day - 1);
ts->tv_sec = (((time_t)days * 24 + ct->hour) * 60 + ct->min) * 60 +
ct->sec;
ts->tv_nsec = ct->nsec;
if (ct_debug)
printf(" = %jd.%09ld\n", (intmax_t)ts->tv_sec, ts->tv_nsec);
return (0);
}
void
clock_ts_to_ct(struct timespec *ts, struct clocktime *ct)
{
time_t i, year, days;
time_t rsec; /* remainder seconds */
time_t secs;
secs = ts->tv_sec;
days = secs / SECDAY;
rsec = secs % SECDAY;
ct->dow = day_of_week(days);
/* Subtract out whole years. */
if (days >= recent_base_days) {
year = recent_base_year;
days -= recent_base_days;
} else {
year = POSIX_BASE_YEAR;
}
for (; days >= days_in_year(year); year++)
days -= days_in_year(year);
ct->year = year;
/* Subtract out whole months, counting them in i. */
for (i = 1; days >= days_in_month(year, i); i++)
days -= days_in_month(year, i);
ct->mon = i;
/* Days are what is left over (+1) from all that. */
ct->day = days + 1;
/* Hours, minutes, seconds are easy */
ct->hour = rsec / 3600;
rsec = rsec % 3600;
ct->min = rsec / 60;
rsec = rsec % 60;
ct->sec = rsec;
ct->nsec = ts->tv_nsec;
if (ct_debug) {
printf("ts_to_ct(%jd.%09ld) = ",
(intmax_t)ts->tv_sec, ts->tv_nsec);
print_ct(ct);
printf("\n");
}
KASSERT(ct->year >= 0 && ct->year < 10000,
("year %d isn't a 4 digit year", ct->year));
KASSERT(ct->mon >= 1 && ct->mon <= 12,
("month %d not in 1-12", ct->mon));
KASSERT(ct->day >= 1 && ct->day <= 31,
("day %d not in 1-31", ct->day));
KASSERT(ct->hour >= 0 && ct->hour <= 23,
("hour %d not in 0-23", ct->hour));
KASSERT(ct->min >= 0 && ct->min <= 59,
("minute %d not in 0-59", ct->min));
/* Not sure if this interface needs to handle leapseconds or not. */
KASSERT(ct->sec >= 0 && ct->sec <= 60,
("seconds %d not in 0-60", ct->sec));
}
int
utc_offset(void)
{
return (tz_minuteswest * 60 + (wall_cmos_clock ? adjkerntz : 0));
}