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 mask;
33 cycle_t cycle_last;
34 u32 mult;
35 u32 shift;
36 u64 xtime_nsec;
37 ktime_t base;
38 };
39
40 /**
41 * struct timekeeper - Structure holding internal timekeeping values.
42 * @tkr_mono: The readout base structure for CLOCK_MONOTONIC
43 * @tkr_raw: The readout base structure for CLOCK_MONOTONIC_RAW
44 * @xtime_sec: Current CLOCK_REALTIME time in seconds
45 * @ktime_sec: Current CLOCK_MONOTONIC 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 * @clock_was_set_seq: The sequence number of clock was set events
52 * @next_leap_ktime: CLOCK_MONOTONIC time value of a pending leap-second
53 * @raw_sec: CLOCK_MONOTONIC_RAW time in seconds
54 * @cycle_interval: Number of clock cycles in one NTP interval
55 * @xtime_interval: Number of clock shifted nano seconds in one NTP
56 * interval.
57 * @xtime_remainder: Shifted nano seconds left over when rounding
58 * @cycle_interval
59 * @raw_interval: Shifted raw nano seconds accumulated per NTP interval.
60 * @ntp_error: Difference between accumulated time and NTP time in ntp
61 * shifted nano seconds.
62 * @ntp_error_shift: Shift conversion between clock shifted nano seconds and
63 * ntp shifted nano seconds.
64 * @last_warning: Warning ratelimiter (DEBUG_TIMEKEEPING)
65 * @underflow_seen: Underflow warning flag (DEBUG_TIMEKEEPING)
66 * @overflow_seen: Overflow warning flag (DEBUG_TIMEKEEPING)
67 *
68 * Note: For timespec(64) based interfaces wall_to_monotonic is what
69 * we need to add to xtime (or xtime corrected for sub jiffie times)
70 * to get to monotonic time. Monotonic is pegged at zero at system
71 * boot time, so wall_to_monotonic will be negative, however, we will
72 * ALWAYS keep the tv_nsec part positive so we can use the usual
73 * normalization.
74 *
75 * wall_to_monotonic is moved after resume from suspend for the
76 * monotonic time not to jump. We need to add total_sleep_time to
77 * wall_to_monotonic to get the real boot based time offset.
78 *
79 * wall_to_monotonic is no longer the boot time, getboottime must be
80 * used instead.
81 */
82 struct timekeeper {
83 struct tk_read_base tkr_mono;
84 struct tk_read_base tkr_raw;
85 u64 xtime_sec;
86 unsigned long ktime_sec;
87 struct timespec64 wall_to_monotonic;
88 ktime_t offs_real;
89 ktime_t offs_boot;
90 ktime_t offs_tai;
91 s32 tai_offset;
92 unsigned int clock_was_set_seq;
93 ktime_t next_leap_ktime;
94 u64 raw_sec;
95
96 /* The following members are for timekeeping internal use */
97 cycle_t cycle_interval;
98 u64 xtime_interval;
99 s64 xtime_remainder;
100 u64 raw_interval;
101 /* The ntp_tick_length() value currently being used.
102 * This cached copy ensures we consistently apply the tick
103 * length for an entire tick, as ntp_tick_length may change
104 * mid-tick, and we don't want to apply that new value to
105 * the tick in progress.
106 */
107 u64 ntp_tick;
108 /* Difference between accumulated time and NTP time in ntp
109 * shifted nano seconds. */
110 s64 ntp_error;
111 u32 ntp_error_shift;
112 u32 ntp_err_mult;
113 #ifdef CONFIG_DEBUG_TIMEKEEPING
114 long last_warning;
115 /*
116 * These simple flag variables are managed
117 * without locks, which is racy, but they are
118 * ok since we don't really care about being
119 * super precise about how many events were
120 * seen, just that a problem was observed.
121 */
122 int underflow_seen;
123 int overflow_seen;
124 #endif
125 };
126
127 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
128
129 extern void update_vsyscall(struct timekeeper *tk);
130 extern void update_vsyscall_tz(void);
131
132 #elif defined(CONFIG_GENERIC_TIME_VSYSCALL_OLD)
133
134 extern void update_vsyscall_old(struct timespec *ts, struct timespec *wtm,
135 struct clocksource *c, u32 mult,
136 cycle_t cycle_last);
137 extern void update_vsyscall_tz(void);
138
139 #else
140
update_vsyscall(struct timekeeper * tk)141 static inline void update_vsyscall(struct timekeeper *tk)
142 {
143 }
update_vsyscall_tz(void)144 static inline void update_vsyscall_tz(void)
145 {
146 }
147 #endif
148
149 #endif /* _LINUX_TIMEKEEPER_INTERNAL_H */
150