timetc.h

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    1 /*-
    2  * SPDX-License-Identifier: Beerware
    3  *
    4  * ----------------------------------------------------------------------------
    5  * "THE BEER-WARE LICENSE" (Revision 42):
    6  * <phk@FreeBSD.ORG> wrote this file.  As long as you retain this notice you
    7  * can do whatever you want with this stuff. If we meet some day, and you think
    8  * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
    9  * ----------------------------------------------------------------------------
   10  *
   11  * $FreeBSD$
   12  */
   13 
   14 #ifndef _SYS_TIMETC_H_
   15 #define _SYS_TIMETC_H_
   16 
   17 #ifndef _KERNEL
   18 #error "no user-serviceable parts inside"
   19 #endif
   20 
   21 /*-
   22  * `struct timecounter' is the interface between the hardware which implements
   23  * a timecounter and the MI code which uses this to keep track of time.
   24  *
   25  * A timecounter is a binary counter which has two properties:
   26  *    * it runs at a fixed, known frequency.
   27  *    * it has sufficient bits to not roll over in less than approximately
   28  *      max(2 msec, 2/HZ seconds).  (The value 2 here is really 1 + delta,
   29  *      for some indeterminate value of delta.)
   30  */
   31 
   32 struct timecounter;
   33 struct vdso_timehands;
   34 struct vdso_timehands32;
   35 typedef u_int timecounter_get_t(struct timecounter *);
   36 typedef void timecounter_pps_t(struct timecounter *);
   37 typedef uint32_t timecounter_fill_vdso_timehands_t(struct vdso_timehands *,
   38     struct timecounter *);
   39 typedef uint32_t timecounter_fill_vdso_timehands32_t(struct vdso_timehands32 *,
   40     struct timecounter *);
   41 
   42 struct timecounter {
   43         timecounter_get_t       *tc_get_timecount;
   44                 /*
   45                  * This function reads the counter.  It is not required to
   46                  * mask any unimplemented bits out, as long as they are
   47                  * constant.
   48                  */
   49         timecounter_pps_t       *tc_poll_pps;
   50                 /*
   51                  * This function is optional.  It will be called whenever the
   52                  * timecounter is rewound, and is intended to check for PPS
   53                  * events.  Normal hardware does not need it but timecounters
   54                  * which latch PPS in hardware (like sys/pci/xrpu.c) do.
   55                  */
   56         u_int                   tc_counter_mask;
   57                 /* This mask should mask off any unimplemented bits. */
   58         uint64_t                tc_frequency;
   59                 /* Frequency of the counter in Hz. */
   60         const char              *tc_name;
   61                 /* Name of the timecounter. */
   62         int                     tc_quality;
   63                 /*
   64                  * Used to determine if this timecounter is better than
   65                  * another timecounter higher means better.  Negative
   66                  * means "only use at explicit request".
   67                  */
   68         u_int                   tc_flags;
   69 #define TC_FLAGS_C2STOP         1       /* Timer dies in C2+. */
   70 #define TC_FLAGS_SUSPEND_SAFE   2       /*
   71                                          * Timer functional across
   72                                          * suspend/resume.
   73                                          */
   74 
   75         void                    *tc_priv;
   76                 /* Pointer to the timecounter's private parts. */
   77         struct timecounter      *tc_next;
   78                 /* Pointer to the next timecounter. */
   79         timecounter_fill_vdso_timehands_t *tc_fill_vdso_timehands;
   80         timecounter_fill_vdso_timehands32_t *tc_fill_vdso_timehands32;
   81 };
   82 
   83 extern struct timecounter *timecounter;
   84 extern int tc_min_ticktock_freq; /*
   85                                   * Minimal tc_ticktock() call frequency,
   86                                   * required to handle counter wraps.
   87                                   */
   88 
   89 u_int64_t tc_getfrequency(void);
   90 void    tc_init(struct timecounter *tc);
   91 void    tc_setclock(struct timespec *ts);
   92 void    tc_ticktock(int cnt);
   93 void    cpu_tick_calibration(void);
   94 
   95 #ifdef SYSCTL_DECL
   96 SYSCTL_DECL(_kern_timecounter);
   97 #endif
   98 
   99 #endif /* !_SYS_TIMETC_H_ */

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

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sys/sys/timetc.h