/*      $OpenBSD: timetc.h,v 1.14 2023/02/04 19:19:35 cheloha Exp $ */

/*
 * Copyright (c) 2000 Poul-Henning Kamp <phk@FreeBSD.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * If we meet some day, and you think this stuff is worth it, you
 * can buy me a beer in return. Poul-Henning Kamp
 */

#ifndef _SYS_TIMETC_H_
#define _SYS_TIMETC_H_

#if !defined(_KERNEL) && !defined(_LIBC)
#error "no user-serviceable parts inside"
#endif

#include <machine/timetc.h>
#include <sys/queue.h>

/*-
 * `struct timecounter' is the interface between the hardware which implements
 * a timecounter and the MI code which uses this to keep track of time.
 *
 * A timecounter is a binary counter which has two properties:
 *    * it runs at a fixed, known frequency.
 *    * it has sufficient bits to not roll over in less than approximately
 *      max(2 msec, 2/HZ seconds).  (The value 2 here is really 1 + delta,
 *      for some indeterminate value of delta.)
 */

struct timecounter;
typedef u_int timecounter_get_t(struct timecounter *);

/*
 * Locks used to protect struct members in this file:
 *      I       immutable after initialization
 *      T       tc_lock
 *      W       windup_mtx
 */

struct timecounter {
        timecounter_get_t       *tc_get_timecount;      /* [I] */
                /*
                 * This function reads the counter.  It is not required to
                 * mask any unimplemented bits out, as long as they are
                 * constant.
                 */
        u_int                   tc_counter_mask;        /* [I] */
                /* This mask should mask off any unimplemented bits. */
        u_int64_t               tc_frequency;           /* [I] */
                /* Frequency of the counter in Hz. */
        char                    *tc_name;               /* [I] */
                /* Name of the timecounter. */
        int                     tc_quality;             /* [I] */
                /*
                 * Used to determine if this timecounter is better than
                 * another timecounter higher means better.  Negative
                 * means "only use at explicit request".
                 */
        void                    *tc_priv;               /* [I] */
                /* Pointer to the timecounter's private parts. */
        int                     tc_user;                /* [I] */
                /* Expose this timecounter to userland. */
        SLIST_ENTRY(timecounter) tc_next;               /* [I] */
                /* Pointer to the next timecounter. */
        int64_t                 tc_freq_adj;            /* [T,W] */
                /* Current frequency adjustment. */
        u_int64_t               tc_precision;           /* [I] */
                /* Precision of the counter.  Computed in tc_init(). */
};

struct timekeep {
        /* set at initialization */
        uint32_t        tk_version;             /* version number */

        /* timehands members */
        uint64_t        tk_scale;
        u_int           tk_offset_count;
        struct bintime  tk_offset;
        struct bintime  tk_naptime;
        struct bintime  tk_boottime;
        volatile u_int  tk_generation;

        /* timecounter members */
        int             tk_user;
        u_int           tk_counter_mask;
};
#define TK_VERSION      0

struct rwlock;
extern struct rwlock tc_lock;

extern struct timecounter *timecounter;

extern struct uvm_object *timekeep_object;
extern struct timekeep *timekeep;

u_int64_t tc_getfrequency(void);
u_int64_t tc_getprecision(void);
void    tc_init(struct timecounter *tc);
void    tc_reset_quality(struct timecounter *, int);
void    tc_setclock(const struct timespec *ts);
void    tc_setrealtimeclock(const struct timespec *ts);
void    tc_ticktock(void);
void    inittimecounter(void);
int     sysctl_tc(int *, u_int, void *, size_t *, void *, size_t);
void    tc_adjfreq(int64_t *, int64_t *);
void    tc_adjtime(int64_t *, int64_t *);

#endif /* !_SYS_TIMETC_H_ */