1 | /* $NetBSD: timetc.h,v 1.6 2009/01/11 02:45:56 christos 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 | #ifndef _KERNEL |
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 | typedef u_int timecounter_get_t(struct timecounter *); |
44 | typedef void timecounter_pps_t(struct timecounter *); |
45 | |
46 | struct timecounter { |
47 | timecounter_get_t *tc_get_timecount; |
48 | /* |
49 | * This function reads the counter. It is not required to |
50 | * mask any unimplemented bits out, as long as they are |
51 | * constant. |
52 | */ |
53 | timecounter_pps_t *tc_poll_pps; |
54 | /* |
55 | * This function is optional. It will be called whenever the |
56 | * timecounter is rewound, and is intended to check for PPS |
57 | * events. Normal hardware does not need it but timecounters |
58 | * which latch PPS in hardware (like sys/pci/xrpu.c) do. |
59 | */ |
60 | u_int tc_counter_mask; |
61 | /* This mask should mask off any unimplemented bits. */ |
62 | u_int64_t tc_frequency; |
63 | /* Frequency of the counter in Hz. */ |
64 | const char *tc_name; |
65 | /* Name of the timecounter. */ |
66 | int tc_quality; |
67 | /* |
68 | * Used to determine if this timecounter is better than |
69 | * another timecounter higher means better. Negative |
70 | * means "only use at explicit request". |
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 | }; |
78 | |
79 | extern struct timecounter *timecounter; |
80 | |
81 | u_int64_t tc_getfrequency(void); |
82 | void tc_init(struct timecounter *tc); |
83 | int tc_detach(struct timecounter *); |
84 | void tc_setclock(const struct timespec *ts); |
85 | void tc_ticktock(void); |
86 | void tc_gonebad(struct timecounter *); |
87 | |
88 | #ifdef SYSCTL_DECL |
89 | SYSCTL_DECL(_kern_timecounter); |
90 | #endif |
91 | |
92 | #endif /* !_SYS_TIMETC_H_ */ |
93 | |