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on clock drivers. This tracks multiple concurrent realtime clock drivers in a list sorted by clock resolution. When system time changes (and periodically) the clock_settime() methods of all registered clocks are invoked. To initialize system time, each driver is tried in turn from best to worst resolution, until one succesfully returns a valid time. The code no longer holds a mutex while calling the clock_settime() and clock_gettime() methods of the registered clocks. This allows clock drivers to do whatever kind of locking or sleeping is necessary (this is especially important for i2c clock chips since i2c drivers often need to sleep). A new clock_register_flags() function allows the clock driver to pass flags. The flags currently defined help support drivers that use their own techniques to avoid roundoff errors (prevents the 4/5 rounding done by the subr_rtc code). A driver which may need to wait for resources (such as bus ownership) may pass a flag to indicate that it will obtain system time for itself after waiting for resources; this is merely an optimization to avoid the common code retrieving a timespec that will never get used. Relnotes: yes Differential Revision: https://reviews.freebsd.org/D11484
126 lines
4.4 KiB
C
126 lines
4.4 KiB
C
/*-
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* Copyright (c) 1996 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Gordon W. Ross
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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* $NetBSD: clock_subr.h,v 1.7 2000/10/03 13:41:07 tsutsui Exp $
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*
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*
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* This file is the central clearing-house for calendrical issues.
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*
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* In general the kernel does not know about minutes, hours, days, timezones,
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* daylight savings time, leap-years and such. All that is theoretically a
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* matter for userland only.
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*
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* Parts of kernel code does however care: badly designed filesystems store
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* timestamps in local time and RTC chips sometimes track time in a local
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* timezone instead of UTC and so on.
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*
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* All that code should go here for service.
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*
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* $FreeBSD$
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*/
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#ifndef _SYS_CLOCK_H_
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#define _SYS_CLOCK_H_
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#ifdef _KERNEL /* No user serviceable parts */
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/*
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* Timezone info from settimeofday(2), usually not used
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*/
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extern int tz_minuteswest;
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extern int tz_dsttime;
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int utc_offset(void);
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/*
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* Structure to hold the values typically reported by time-of-day clocks.
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* This can be passed to the generic conversion functions to be converted
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* to a struct timespec.
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*/
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struct clocktime {
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int year; /* year (4 digit year) */
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int mon; /* month (1 - 12) */
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int day; /* day (1 - 31) */
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int hour; /* hour (0 - 23) */
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int min; /* minute (0 - 59) */
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int sec; /* second (0 - 59) */
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int dow; /* day of week (0 - 6; 0 = Sunday) */
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long nsec; /* nano seconds */
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};
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int clock_ct_to_ts(struct clocktime *, struct timespec *);
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void clock_ts_to_ct(struct timespec *, struct clocktime *);
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/*
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* Time-of-day clock register/unregister functions, and associated flags. These
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* functions can sleep. Upon return from unregister, the clock's methods are
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* not running and will not be called again.
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*
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* Flags:
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*
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* CLOCKF_SETTIME_NO_TS
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* Do not pass a timespec to clock_settime(), the driver obtains its own time
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* and applies its own adjustments (this flag implies CLOCKF_SETTIME_NO_ADJ).
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*
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* CLOCKF_SETTIME_NO_ADJ
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* Do not apply utc offset and resolution/accuracy adjustments to the value
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* passed to clock_settime(), the driver applies them itself.
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*
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* CLOCKF_GETTIME_NO_ADJ
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* Do not apply utc offset and resolution/accuracy adjustments to the value
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* returned from clock_gettime(), the driver has already applied them.
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*/
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#define CLOCKF_SETTIME_NO_TS 0x00000001
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#define CLOCKF_SETTIME_NO_ADJ 0x00000002
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#define CLOCKF_GETTIME_NO_ADJ 0x00000004
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void clock_register(device_t _clockdev, long _resolution_us);
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void clock_register_flags(device_t _clockdev, long _resolution_us, int _flags);
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void clock_unregister(device_t _clockdev);
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/*
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* BCD to decimal and decimal to BCD.
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*/
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#define FROMBCD(x) bcd2bin(x)
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#define TOBCD(x) bin2bcd(x)
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/* Some handy constants. */
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#define SECDAY (24 * 60 * 60)
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#define SECYR (SECDAY * 365)
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/* Traditional POSIX base year */
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#define POSIX_BASE_YEAR 1970
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void timespec2fattime(struct timespec *tsp, int utc, u_int16_t *ddp, u_int16_t *dtp, u_int8_t *dhp);
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void fattime2timespec(unsigned dd, unsigned dt, unsigned dh, int utc, struct timespec *tsp);
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#endif /* _KERNEL */
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#endif /* !_SYS_CLOCK_H_ */
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