1/*-
2 * ----------------------------------------------------------------------------
3 * "THE BEER-WARE LICENSE" (Revision 42):
4 * <phk@FreeBSD.ORG> wrote this file.  As long as you retain this notice you
5 * can do whatever you want with this stuff. If we meet some day, and you think
6 * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
7 * ----------------------------------------------------------------------------
8 *
9 * $FreeBSD$
10 */
11
12#ifndef _SYS_TIMETC_H_
13#define	_SYS_TIMETC_H_
14
15#ifndef _KERNEL
16#error "no user-serviceable parts inside"
17#endif
18
19/*-
20 * `struct timecounter' is the interface between the hardware which implements
21 * a timecounter and the MI code which uses this to keep track of time.
22 *
23 * A timecounter is a binary counter which has two properties:
24 *    * it runs at a fixed, known frequency.
25 *    * it has sufficient bits to not roll over in less than approximately
26 *      max(2 msec, 2/HZ seconds).  (The value 2 here is really 1 + delta,
27 *      for some indeterminate value of delta.)
28 */
29
30struct timecounter;
31typedef u_int timecounter_get_t(struct timecounter *);
32typedef void timecounter_pps_t(struct timecounter *);
33
34struct timecounter {
35	timecounter_get_t	*tc_get_timecount;
36		/*
37		 * This function reads the counter.  It is not required to
38		 * mask any unimplemented bits out, as long as they are
39		 * constant.
40		 */
41	timecounter_pps_t	*tc_poll_pps;
42		/*
43		 * This function is optional.  It will be called whenever the
44		 * timecounter is rewound, and is intended to check for PPS
45		 * events.  Normal hardware does not need it but timecounters
46		 * which latch PPS in hardware (like sys/pci/xrpu.c) do.
47		 */
48	u_int 			tc_counter_mask;
49		/* This mask should mask off any unimplemented bits. */
50	uint64_t		tc_frequency;
51		/* Frequency of the counter in Hz. */
52	char			*tc_name;
53		/* Name of the timecounter. */
54	int			tc_quality;
55		/*
56		 * Used to determine if this timecounter is better than
57		 * another timecounter higher means better.  Negative
58		 * means "only use at explicit request".
59		 */
60	u_int			tc_flags;
61#define	TC_FLAGS_C3STOP		1	/* Timer dies in C3. */
62#define	TC_FLAGS_SUSPEND_SAFE	2	/*
63					 * Timer functional across
64					 * suspend/resume.
65					 */
66
67	void			*tc_priv;
68		/* Pointer to the timecounter's private parts. */
69	struct timecounter	*tc_next;
70		/* Pointer to the next timecounter. */
71};
72
73extern struct timecounter *timecounter;
74extern int tc_min_ticktock_freq; /*
75				  * Minimal tc_ticktock() call frequency,
76				  * required to handle counter wraps.
77				  */
78
79u_int64_t tc_getfrequency(void);
80void	tc_init(struct timecounter *tc);
81void	tc_setclock(struct timespec *ts);
82void	tc_ticktock(int cnt);
83void	cpu_tick_calibration(void);
84
85#ifdef SYSCTL_DECL
86SYSCTL_DECL(_kern_timecounter);
87#endif
88
89#endif /* !_SYS_TIMETC_H_ */
90