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 * @ktime_sec: Current CLOCK_MONOTONIC time in seconds
47 * @wall_to_monotonic: CLOCK_REALTIME to CLOCK_MONOTONIC offset
48 * @offs_real: Offset clock monotonic -> clock realtime
49 * @offs_boot: Offset clock monotonic -> clock boottime
50 * @offs_tai: Offset clock monotonic -> clock tai
51 * @tai_offset: The current UTC to TAI offset in seconds
52 * @clock_was_set_seq: The sequence number of clock was set events
53 * @next_leap_ktime: CLOCK_MONOTONIC time value of a pending leap-second
54 * @raw_time: Monotonic raw base time in timespec64 format
55 * @cycle_interval: Number of clock cycles in one NTP interval
56 * @xtime_interval: Number of clock shifted nano seconds in one NTP
57 * interval.
58 * @xtime_remainder: Shifted nano seconds left over when rounding
59 * @cycle_interval
60 * @raw_interval: Raw nano seconds accumulated per NTP interval.
61 * @ntp_error: Difference between accumulated time and NTP time in ntp
62 * shifted nano seconds.
63 * @ntp_error_shift: Shift conversion between clock shifted nano seconds and
64 * ntp shifted nano seconds.
65 * @last_warning: Warning ratelimiter (DEBUG_TIMEKEEPING)
66 * @underflow_seen: Underflow warning flag (DEBUG_TIMEKEEPING)
67 * @overflow_seen: Overflow warning flag (DEBUG_TIMEKEEPING)
68 *
69 * Note: For timespec(64) based interfaces wall_to_monotonic is what
70 * we need to add to xtime (or xtime corrected for sub jiffie times)
71 * to get to monotonic time. Monotonic is pegged at zero at system
72 * boot time, so wall_to_monotonic will be negative, however, we will
73 * ALWAYS keep the tv_nsec part positive so we can use the usual
74 * normalization.
75 *
76 * wall_to_monotonic is moved after resume from suspend for the
77 * monotonic time not to jump. We need to add total_sleep_time to
78 * wall_to_monotonic to get the real boot based time offset.
79 *
80 * wall_to_monotonic is no longer the boot time, getboottime must be
81 * used instead.
82 */
83 struct timekeeper {
84 struct tk_read_base tkr_mono;
85 struct tk_read_base tkr_raw;
86 u64 xtime_sec;
87 unsigned long ktime_sec;
88 struct timespec64 wall_to_monotonic;
89 ktime_t offs_real;
90 ktime_t offs_boot;
91 ktime_t offs_tai;
92 s32 tai_offset;
93 unsigned int clock_was_set_seq;
94 ktime_t next_leap_ktime;
95 struct timespec64 raw_time;
96
97 /* The following members are for timekeeping internal use */
98 cycle_t cycle_interval;
99 u64 xtime_interval;
100 s64 xtime_remainder;
101 u32 raw_interval;
102 /* The ntp_tick_length() value currently being used.
103 * This cached copy ensures we consistently apply the tick
104 * length for an entire tick, as ntp_tick_length may change
105 * mid-tick, and we don't want to apply that new value to
106 * the tick in progress.
107 */
108 u64 ntp_tick;
109 /* Difference between accumulated time and NTP time in ntp
110 * shifted nano seconds. */
111 s64 ntp_error;
112 u32 ntp_error_shift;
113 u32 ntp_err_mult;
114 #ifdef CONFIG_DEBUG_TIMEKEEPING
115 long last_warning;
116 /*
117 * These simple flag variables are managed
118 * without locks, which is racy, but they are
119 * ok since we don't really care about being
120 * super precise about how many events were
121 * seen, just that a problem was observed.
122 */
123 int underflow_seen;
124 int overflow_seen;
125 #endif
126 };
127
128 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
129
130 extern void update_vsyscall(struct timekeeper *tk);
131 extern void update_vsyscall_tz(void);
132
133 #elif defined(CONFIG_GENERIC_TIME_VSYSCALL_OLD)
134
135 extern void update_vsyscall_old(struct timespec *ts, struct timespec *wtm,
136 struct clocksource *c, u32 mult,
137 cycle_t cycle_last);
138 extern void update_vsyscall_tz(void);
139
140 #else
141
update_vsyscall(struct timekeeper * tk)142 static inline void update_vsyscall(struct timekeeper *tk)
143 {
144 }
update_vsyscall_tz(void)145 static inline void update_vsyscall_tz(void)
146 {
147 }
148 #endif
149
150 #endif /* _LINUX_TIMEKEEPER_INTERNAL_H */
151