timetc.h revision 305866 
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: stable/11/sys/sys/timetc.h 305866 2016-09-16 10:04:28Z kib $
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;
31struct vdso_timehands;
32struct vdso_timehands32;
33typedef u_int timecounter_get_t(struct timecounter *);
34typedef void timecounter_pps_t(struct timecounter *);
35typedef uint32_t timecounter_fill_vdso_timehands_t(struct vdso_timehands *,
36    struct timecounter *);
37typedef uint32_t timecounter_fill_vdso_timehands32_t(struct vdso_timehands32 *,
38    struct timecounter *);
39
40struct timecounter {
41	timecounter_get_t	*tc_get_timecount;
42		/*
43		 * This function reads the counter.  It is not required to
44		 * mask any unimplemented bits out, as long as they are
45		 * constant.
46		 */
47	timecounter_pps_t	*tc_poll_pps;
48		/*
49		 * This function is optional.  It will be called whenever the
50		 * timecounter is rewound, and is intended to check for PPS
51		 * events.  Normal hardware does not need it but timecounters
52		 * which latch PPS in hardware (like sys/pci/xrpu.c) do.
53		 */
54	u_int 			tc_counter_mask;
55		/* This mask should mask off any unimplemented bits. */
56	uint64_t		tc_frequency;
57		/* Frequency of the counter in Hz. */
58	const char		*tc_name;
59		/* Name of the timecounter. */
60	int			tc_quality;
61		/*
62		 * Used to determine if this timecounter is better than
63		 * another timecounter higher means better.  Negative
64		 * means "only use at explicit request".
65		 */
66	u_int			tc_flags;
67#define	TC_FLAGS_C2STOP		1	/* Timer dies in C2+. */
68#define	TC_FLAGS_SUSPEND_SAFE	2	/*
69					 * Timer functional across
70					 * suspend/resume.
71					 */
72
73	void			*tc_priv;
74		/* Pointer to the timecounter's private parts. */
75	struct timecounter	*tc_next;
76		/* Pointer to the next timecounter. */
77	timecounter_fill_vdso_timehands_t *tc_fill_vdso_timehands;
78	timecounter_fill_vdso_timehands32_t *tc_fill_vdso_timehands32;
79};
80
81extern struct timecounter *timecounter;
82extern int tc_min_ticktock_freq; /*
83				  * Minimal tc_ticktock() call frequency,
84				  * required to handle counter wraps.
85				  */
86
87u_int64_t tc_getfrequency(void);
88void	tc_init(struct timecounter *tc);
89void	tc_setclock(struct timespec *ts);
90void	tc_ticktock(int cnt);
91void	cpu_tick_calibration(void);
92
93#ifdef SYSCTL_DECL
94SYSCTL_DECL(_kern_timecounter);
95#endif
96
97#endif /* !_SYS_TIMETC_H_ */
98