FreeBSD/Linux Kernel Cross Reference
sys/sys/clock.h

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 1996 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * This code is derived from software contributed to The NetBSD Foundation
      * by Gordon W. Ross
      *
     * 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.
     *
     * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
     *
     *      $NetBSD: clock_subr.h,v 1.7 2000/10/03 13:41:07 tsutsui Exp $
     *
     *
     * This file is the central clearing-house for calendrical issues.
     *
     * In general the kernel does not know about minutes, hours, days, timezones,
     * daylight savings time, leap-years and such.  All that is theoretically a
     * matter for userland only.
     *
     * Parts of kernel code does however care: badly designed filesystems store
     * timestamps in local time and RTC chips sometimes track time in a local
     * timezone instead of UTC and so on.
     *
     * All that code should go here for service.
     *
     * $FreeBSD$
     */
    
    #ifndef _SYS_CLOCK_H_
    #define _SYS_CLOCK_H_
    
    #ifdef _KERNEL          /* No user serviceable parts */
    
    /*
     * Timezone info from settimeofday(2), usually not used
     */
    extern int tz_minuteswest;
    extern int tz_dsttime;
    
    int utc_offset(void);
    
    /*
     * Structure to hold the values typically reported by time-of-day clocks,
     * expressed as binary integers (see below for a BCD version).  This can be
     * passed to the conversion functions to be converted to/from a struct timespec.
     *
     * On input, the year is interpreted as follows:
     *       0 -   69 = 2000 - 2069
     *      70 -   99 = 1970 - 1999
     *     100 -  199 = 2000 - 2099 (Supports hardware "century bit".)
     *     200 - 1969 = Invalid.
     *    1970 - 9999 = Full 4-digit century+year.
     *
     * The dow field is ignored (not even validated) on input, but is always
     * populated with day-of-week on output.
     *
     * clock_ct_to_ts() returns EINVAL if any values are out of range.  The year
     * field will always be 4-digit on output.
     */
    struct clocktime {
            int     year;                   /* year (4 digit year) */
            int     mon;                    /* month (1 - 12) */
            int     day;                    /* day (1 - 31) */
            int     hour;                   /* hour (0 - 23) */
            int     min;                    /* minute (0 - 59) */
            int     sec;                    /* second (0 - 59) */
            int     dow;                    /* day of week (0 - 6; 0 = Sunday) */
            long    nsec;                   /* nano seconds */
    };
    
    int clock_ct_to_ts(const struct clocktime *, struct timespec *);
    void clock_ts_to_ct(const struct timespec *, struct clocktime *);
    
    /*
     * Structure to hold the values typically reported by time-of-day clocks,
     * expressed as BCD.  This can be passed to the conversion functions to be
     * converted to/from a struct timespec.
     *
     * The clock_bcd_to_ts() function interprets the values in the year through sec
    * fields as BCD numbers, and returns EINVAL if any BCD values are out of range.
    * After conversion to binary, the values are passed to clock_ct_to_ts() and
    * undergo further validation as described above.  Year may be 2 or 4-digit BCD,
    * interpreted as described above.  The nsec field is binary.  If the ampm arg
    * is true, the incoming hour and ispm values are interpreted as 12-hour am/pm
    * representation of the hour, otherwise hour is interpreted as 24-hour and ispm
    * is ignored.
    *
    * The clock_ts_to_bcd() function converts the timespec to BCD values stored
    * into year through sec.  The value in year will be 4-digit BCD (e.g.,
    * 0x2017). The mon through sec values will be 2-digit BCD.  The nsec field will
    * be binary, and the range of dow makes its binary and BCD values identical.
    * If the ampm arg is true, the hour and ispm fields are set to the 12-hour
    * time plus a pm flag, otherwise the hour is set to 24-hour time and ispm is
    * set to false.
    */
   struct bcd_clocktime {
           uint16_t year;                  /* year (2 or 4 digit year) */
           uint8_t  mon;                   /* month (1 - 12) */
           uint8_t  day;                   /* day (1 - 31) */
           uint8_t  hour;                  /* hour (0 - 23 or 1 - 12) */
           uint8_t  min;                   /* minute (0 - 59) */
           uint8_t  sec;                   /* second (0 - 59) */
           uint8_t  dow;                   /* day of week (0 - 6; 0 = Sunday) */
           long     nsec;                  /* nanoseconds */
           bool     ispm;                  /* true if hour represents pm time */
   };
   
   int clock_bcd_to_ts(const struct bcd_clocktime *, struct timespec *, bool ampm);
   void clock_ts_to_bcd(const struct timespec *, struct bcd_clocktime *, bool ampm);
   
   /*
    * Time-of-day clock functions and flags.  These functions might sleep.
    *
    * clock_register and clock_unregister() do what they say.  Upon return from
    * unregister, the clock's methods are not running and will not be called again.
    *
    * clock_schedule() requests that a registered clock's clock_settime() calls
    * happen at the given offset into the second.  The default is 0, meaning no
    * specific scheduling.  To schedule the call as soon after top-of-second as
    * possible, specify 1.  Each clock has its own schedule, but taskqueue_thread
    * is shared by many tasks; the timing of the call is not guaranteed.
    *
    * Flags:
    *
    *  CLOCKF_SETTIME_NO_TS
    *    Do not pass a timespec to clock_settime(), the driver obtains its own time
    *    and applies its own adjustments (this flag implies CLOCKF_SETTIME_NO_ADJ).
    *
    *  CLOCKF_SETTIME_NO_ADJ
    *    Do not apply utc offset and resolution/accuracy adjustments to the value
    *    passed to clock_settime(), the driver applies them itself.
    *
    *  CLOCKF_GETTIME_NO_ADJ
    *    Do not apply utc offset and resolution/accuracy adjustments to the value
    *    returned from clock_gettime(), the driver has already applied them.
    */
   
   #define CLOCKF_SETTIME_NO_TS    0x00000001
   #define CLOCKF_SETTIME_NO_ADJ   0x00000002
   #define CLOCKF_GETTIME_NO_ADJ   0x00000004
   
   void clock_register(device_t _clockdev, long _resolution_us);
   void clock_register_flags(device_t _clockdev, long _resolution_us, int _flags);
   void clock_schedule(device_t clockdev, u_int _offsetns);
   void clock_unregister(device_t _clockdev);
   
   /*
    * BCD to decimal and decimal to BCD.
    */
   #define FROMBCD(x)      bcd2bin(x)
   #define TOBCD(x)        bin2bcd(x)
   
   /* Some handy constants. */
   #define SECDAY          (24 * 60 * 60)
   #define SECYR           (SECDAY * 365)
   
   /* Traditional POSIX base year */
   #define POSIX_BASE_YEAR 1970
   
   void timespec2fattime(const struct timespec *tsp, int utc, u_int16_t *ddp,
       u_int16_t *dtp, u_int8_t *dhp);
   void fattime2timespec(unsigned dd, unsigned dt, unsigned dh, int utc,
       struct timespec *tsp);
   
   /*
    * Print a [bcd_]clocktime or timespec, optionally with fractional seconds.  The
    * nsdig argument can range from 0-9, and specifies how many decimal digits to
    * display for fractional seconds.
    */
   void clock_print_bcd(const struct bcd_clocktime *bct, int nsdig);
   void clock_print_ct(const struct clocktime *ct, int nsdig);
   void clock_print_ts(const struct timespec  *ts, int nsdig);
   
   /*
    * Debugging helpers for RTC clock drivers.  Print a [bcd_]clocktime or
    * timespec, only if rtc clock debugging has been enabled.  The rw argument is
    * one of CLOCK_DBG_READ or CLOCK_DBG_WRITE.
    */
   #define CLOCK_DBG_READ  0x01
   #define CLOCK_DBG_WRITE 0x02
   void clock_dbgprint_bcd(device_t dev, int rw, const struct bcd_clocktime *bct);
   void clock_dbgprint_ct(device_t dev, int rw, const struct clocktime *ct);
   void clock_dbgprint_err(device_t dev, int rw, int err);
   void clock_dbgprint_ts(device_t dev, int rw, const struct timespec *ts);
   
   #endif /* _KERNEL */
   
   #endif /* !_SYS_CLOCK_H_ */

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