FreeBSD/Linux Kernel Cross Reference
sys/sys/timetc.h
1 /* $NetBSD: timetc.h,v 1.9 2020/09/04 00:36:07 thorpej Exp $ */
2
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: src/sys/sys/timetc.h,v 1.58 2003/08/16 08:23:52 phk Exp $
12 */
13
14 #ifndef _SYS_TIMETC_H_
15 #define _SYS_TIMETC_H_
16
17 #if !defined(_KERNEL) && !defined(_KMEMUSER)
18 #error "no user-serviceable parts inside"
19 #endif
20
21 /*
22 * max recommended timecounter name length
23 *
24 * it is not a functional limit but names longer
25 * then that will not be controllable via
26 * sysctl. see kern/kern_tc.c for the sysctl
27 * implementation.
28 */
29 #define MAX_TCNAMELEN 64
30
31 /*-
32 * `struct timecounter' is the interface between the hardware which implements
33 * a timecounter and the MI code which uses this to keep track of time.
34 *
35 * A timecounter is a binary counter which has two properties:
36 * * it runs at a fixed, known frequency.
37 * * it has sufficient bits to not roll over in less than approximately
38 * max(2 msec, 2/HZ seconds). (The value 2 here is really 1 + delta,
39 * for some indeterminate value of delta.)
40 */
41
42 struct timecounter;
43 struct timespec;
44 typedef u_int timecounter_get_t(struct timecounter *);
45 typedef void timecounter_pps_t(struct timecounter *);
46
47 struct timecounter {
48 timecounter_get_t *tc_get_timecount;
49 /*
50 * This function reads the counter. It is not required to
51 * mask any unimplemented bits out, as long as they are
52 * constant.
53 */
54 timecounter_pps_t *tc_poll_pps;
55 /*
56 * This function is optional. It will be called whenever the
57 * timecounter is rewound, and is intended to check for PPS
58 * events. Normal hardware does not need it but timecounters
59 * which latch PPS in hardware (like sys/pci/xrpu.c) do.
60 */
61 u_int tc_counter_mask;
62 /* This mask should mask off any unimplemented bits. */
63 uint64_t tc_frequency;
64 /* Frequency of the counter in Hz. */
65 const char *tc_name;
66 /* Name of the timecounter. */
67 int tc_quality;
68 /*
69 * Used to determine if this timecounter is better than
70 * another timecounter higher means better. Negative
71 * means "only use at explicit request".
72 */
73
74 void *tc_priv;
75 /* Pointer to the timecounter's private parts. */
76 struct timecounter *tc_next;
77 /* Pointer to the next timecounter. */
78 };
79
80 #ifdef _KERNEL
81 extern struct timecounter *timecounter;
82
83 uint64_t tc_getfrequency(void);
84 void tc_init(struct timecounter *tc);
85 int tc_detach(struct timecounter *);
86 void tc_setclock(const struct timespec *ts);
87 void tc_ticktock(void);
88 void tc_gonebad(struct timecounter *);
89
90 #ifdef SYSCTL_DECL
91 SYSCTL_DECL(_kern_timecounter);
92 #endif
93 #endif /* _KERNEL */
94
95 #endif /* !_SYS_TIMETC_H_ */
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