1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * You SHOULD NOT be including this unless you're vsyscall
4 * handling code or timekeeping internal code!
5 */
6
7#ifndef _LINUX_TIMEKEEPER_INTERNAL_H
8#define _LINUX_TIMEKEEPER_INTERNAL_H
9
10#include <linux/clocksource.h>
11#include <linux/jiffies.h>
12#include <linux/time.h>
13
14/**
15 * struct tk_read_base - base structure for timekeeping readout
16 * @clock:	Current clocksource used for timekeeping.
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 * @base_real:	Nanoseconds base value for clock REALTIME readout
24 *
25 * This struct has size 56 byte on 64 bit. Together with a seqcount it
26 * occupies a single 64byte cache line.
27 *
28 * The struct is separate from struct timekeeper as it is also used
29 * for a fast NMI safe accessors.
30 *
31 * @base_real is for the fast NMI safe accessor to allow reading clock
32 * realtime from any context.
33 */
34struct tk_read_base {
35	struct clocksource	*clock;
36	u64			mask;
37	u64			cycle_last;
38	u32			mult;
39	u32			shift;
40	u64			xtime_nsec;
41	ktime_t			base;
42	u64			base_real;
43};
44
45/**
46 * struct timekeeper - Structure holding internal timekeeping values.
47 * @tkr_mono:		The readout base structure for CLOCK_MONOTONIC
48 * @tkr_raw:		The readout base structure for CLOCK_MONOTONIC_RAW
49 * @xtime_sec:		Current CLOCK_REALTIME time in seconds
50 * @ktime_sec:		Current CLOCK_MONOTONIC time in seconds
51 * @wall_to_monotonic:	CLOCK_REALTIME to CLOCK_MONOTONIC offset
52 * @offs_real:		Offset clock monotonic -> clock realtime
53 * @offs_boot:		Offset clock monotonic -> clock boottime
54 * @offs_tai:		Offset clock monotonic -> clock tai
55 * @tai_offset:		The current UTC to TAI offset in seconds
56 * @clock_was_set_seq:	The sequence number of clock was set events
57 * @cs_was_changed_seq:	The sequence number of clocksource change events
58 * @next_leap_ktime:	CLOCK_MONOTONIC time value of a pending leap-second
59 * @raw_sec:		CLOCK_MONOTONIC_RAW  time in seconds
60 * @monotonic_to_boot:	CLOCK_MONOTONIC to CLOCK_BOOTTIME offset
61 * @cycle_interval:	Number of clock cycles in one NTP interval
62 * @xtime_interval:	Number of clock shifted nano seconds in one NTP
63 *			interval.
64 * @xtime_remainder:	Shifted nano seconds left over when rounding
65 *			@cycle_interval
66 * @raw_interval:	Shifted raw nano seconds accumulated per NTP interval.
67 * @ntp_error:		Difference between accumulated time and NTP time in ntp
68 *			shifted nano seconds.
69 * @ntp_error_shift:	Shift conversion between clock shifted nano seconds and
70 *			ntp shifted nano seconds.
71 * @last_warning:	Warning ratelimiter (DEBUG_TIMEKEEPING)
72 * @underflow_seen:	Underflow warning flag (DEBUG_TIMEKEEPING)
73 * @overflow_seen:	Overflow warning flag (DEBUG_TIMEKEEPING)
74 *
75 * Note: For timespec(64) based interfaces wall_to_monotonic is what
76 * we need to add to xtime (or xtime corrected for sub jiffie times)
77 * to get to monotonic time.  Monotonic is pegged at zero at system
78 * boot time, so wall_to_monotonic will be negative, however, we will
79 * ALWAYS keep the tv_nsec part positive so we can use the usual
80 * normalization.
81 *
82 * wall_to_monotonic is moved after resume from suspend for the
83 * monotonic time not to jump. We need to add total_sleep_time to
84 * wall_to_monotonic to get the real boot based time offset.
85 *
86 * wall_to_monotonic is no longer the boot time, getboottime must be
87 * used instead.
88 *
89 * @monotonic_to_boottime is a timespec64 representation of @offs_boot to
90 * accelerate the VDSO update for CLOCK_BOOTTIME.
91 */
92struct timekeeper {
93	struct tk_read_base	tkr_mono;
94	struct tk_read_base	tkr_raw;
95	u64			xtime_sec;
96	unsigned long		ktime_sec;
97	struct timespec64	wall_to_monotonic;
98	ktime_t			offs_real;
99	ktime_t			offs_boot;
100	ktime_t			offs_tai;
101	s32			tai_offset;
102	unsigned int		clock_was_set_seq;
103	u8			cs_was_changed_seq;
104	ktime_t			next_leap_ktime;
105	u64			raw_sec;
106	struct timespec64	monotonic_to_boot;
107
108	/* The following members are for timekeeping internal use */
109	u64			cycle_interval;
110	u64			xtime_interval;
111	s64			xtime_remainder;
112	u64			raw_interval;
113	/* The ntp_tick_length() value currently being used.
114	 * This cached copy ensures we consistently apply the tick
115	 * length for an entire tick, as ntp_tick_length may change
116	 * mid-tick, and we don't want to apply that new value to
117	 * the tick in progress.
118	 */
119	u64			ntp_tick;
120	/* Difference between accumulated time and NTP time in ntp
121	 * shifted nano seconds. */
122	s64			ntp_error;
123	u32			ntp_error_shift;
124	u32			ntp_err_mult;
125	/* Flag used to avoid updating NTP twice with same second */
126	u32			skip_second_overflow;
127#ifdef CONFIG_DEBUG_TIMEKEEPING
128	long			last_warning;
129	/*
130	 * These simple flag variables are managed
131	 * without locks, which is racy, but they are
132	 * ok since we don't really care about being
133	 * super precise about how many events were
134	 * seen, just that a problem was observed.
135	 */
136	int			underflow_seen;
137	int			overflow_seen;
138#endif
139};
140
141#ifdef CONFIG_GENERIC_TIME_VSYSCALL
142
143extern void update_vsyscall(struct timekeeper *tk);
144extern void update_vsyscall_tz(void);
145
146#else
147
148static inline void update_vsyscall(struct timekeeper *tk)
149{
150}
151static inline void update_vsyscall_tz(void)
152{
153}
154#endif
155
156#endif /* _LINUX_TIMEKEEPER_INTERNAL_H */
157