FreeBSD/Linux Kernel Cross Reference
sys/sys/timetc.h
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: releng/10.4/sys/sys/timetc.h 280973 2015-04-02 01:02:42Z jhb $
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
30 struct timecounter;
31 typedef u_int timecounter_get_t(struct timecounter *);
32 typedef void timecounter_pps_t(struct timecounter *);
33
34 struct 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_C2STOP 1 /* Timer dies in C2+. */
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
73 extern struct timecounter *timecounter;
74 extern int tc_min_ticktock_freq; /*
75 * Minimal tc_ticktock() call frequency,
76 * required to handle counter wraps.
77 */
78
79 u_int64_t tc_getfrequency(void);
80 void tc_init(struct timecounter *tc);
81 void tc_setclock(struct timespec *ts);
82 void tc_ticktock(int cnt);
83 void cpu_tick_calibration(void);
84
85 #ifdef SYSCTL_DECL
86 SYSCTL_DECL(_kern_timecounter);
87 #endif
88
89 #endif /* !_SYS_TIMETC_H_ */
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