1 /*
2 * You SHOULD NOT be including this unless you're vsyscall
3 * handling code or timekeeping internal code!
4 */
5
6 #ifndef _LINUX_TIMEKEEPER_INTERNAL_H
7 #define _LINUX_TIMEKEEPER_INTERNAL_H
8
9 #include <linux/clocksource.h>
10 #include <linux/jiffies.h>
11 #include <linux/time.h>
12
13 /**
14 * struct tk_read_base - base structure for timekeeping readout
15 * @clock: Current clocksource used for timekeeping.
16 * @read: Read function of @clock
17 * @mask: Bitmask for two's complement subtraction of non 64bit clocks
18 * @cycle_last: @clock cycle value at last update
19 * @mult: (NTP adjusted) multiplier for scaled math conversion
20 * @shift: Shift value for scaled math conversion
21 * @xtime_nsec: Shifted (fractional) nano seconds offset for readout
22 * @base: ktime_t (nanoseconds) base time for readout
23 *
24 * This struct has size 56 byte on 64 bit. Together with a seqcount it
25 * occupies a single 64byte cache line.
26 *
27 * The struct is separate from struct timekeeper as it is also used
28 * for a fast NMI safe accessors.
29 */
30 struct tk_read_base {
31 struct clocksource *clock;
32 cycle_t (*read)(struct clocksource *cs);
33 cycle_t mask;
34 cycle_t cycle_last;
35 u32 mult;
36 u32 shift;
37 u64 xtime_nsec;
38 ktime_t base;
39 };
40
41 /**
42 * struct timekeeper - Structure holding internal timekeeping values.
43 * @tkr_mono: The readout base structure for CLOCK_MONOTONIC
44 * @tkr_raw: The readout base structure for CLOCK_MONOTONIC_RAW
45 * @xtime_sec: Current CLOCK_REALTIME time in seconds
46 * @wall_to_monotonic: CLOCK_REALTIME to CLOCK_MONOTONIC offset
47 * @offs_real: Offset clock monotonic -> clock realtime
48 * @offs_boot: Offset clock monotonic -> clock boottime
49 * @offs_tai: Offset clock monotonic -> clock tai
50 * @tai_offset: The current UTC to TAI offset in seconds
51 * @raw_sec: CLOCK_MONOTONIC_RAW time in seconds
52 * @cycle_interval: Number of clock cycles in one NTP interval
53 * @xtime_interval: Number of clock shifted nano seconds in one NTP
54 * interval.
55 * @xtime_remainder: Shifted nano seconds left over when rounding
56 * @cycle_interval
57 * @raw_interval: Shifted raw nano seconds accumulated per NTP interval.
58 * @ntp_error: Difference between accumulated time and NTP time in ntp
59 * shifted nano seconds.
60 * @ntp_error_shift: Shift conversion between clock shifted nano seconds and
61 * ntp shifted nano seconds.
62 *
63 * Note: For timespec(64) based interfaces wall_to_monotonic is what
64 * we need to add to xtime (or xtime corrected for sub jiffie times)
65 * to get to monotonic time. Monotonic is pegged at zero at system
66 * boot time, so wall_to_monotonic will be negative, however, we will
67 * ALWAYS keep the tv_nsec part positive so we can use the usual
68 * normalization.
69 *
70 * wall_to_monotonic is moved after resume from suspend for the
71 * monotonic time not to jump. We need to add total_sleep_time to
72 * wall_to_monotonic to get the real boot based time offset.
73 *
74 * wall_to_monotonic is no longer the boot time, getboottime must be
75 * used instead.
76 */
77 struct timekeeper {
78 struct tk_read_base tkr_mono;
79 struct tk_read_base tkr_raw;
80 u64 xtime_sec;
81 struct timespec64 wall_to_monotonic;
82 ktime_t offs_real;
83 ktime_t offs_boot;
84 ktime_t offs_tai;
85 s32 tai_offset;
86 u64 raw_sec;
87
88 /* The following members are for timekeeping internal use */
89 cycle_t cycle_interval;
90 u64 xtime_interval;
91 s64 xtime_remainder;
92 u64 raw_interval;
93 /* The ntp_tick_length() value currently being used.
94 * This cached copy ensures we consistently apply the tick
95 * length for an entire tick, as ntp_tick_length may change
96 * mid-tick, and we don't want to apply that new value to
97 * the tick in progress.
98 */
99 u64 ntp_tick;
100 /* Difference between accumulated time and NTP time in ntp
101 * shifted nano seconds. */
102 s64 ntp_error;
103 u32 ntp_error_shift;
104 u32 ntp_err_mult;
105 };
106
107 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
108
109 extern void update_vsyscall(struct timekeeper *tk);
110 extern void update_vsyscall_tz(void);
111
112 #elif defined(CONFIG_GENERIC_TIME_VSYSCALL_OLD)
113
114 extern void update_vsyscall_old(struct timespec *ts, struct timespec *wtm,
115 struct clocksource *c, u32 mult,
116 cycle_t cycle_last);
117 extern void update_vsyscall_tz(void);
118
119 #else
120
update_vsyscall(struct timekeeper * tk)121 static inline void update_vsyscall(struct timekeeper *tk)
122 {
123 }
update_vsyscall_tz(void)124 static inline void update_vsyscall_tz(void)
125 {
126 }
127 #endif
128
129 #endif /* _LINUX_TIMEKEEPER_INTERNAL_H */
130