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Linux/include/linux/timekeeper_internal.h

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  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  * @cs_was_changed_seq: The sequence number of clocksource change events
 54  * @next_leap_ktime:    CLOCK_MONOTONIC time value of a pending leap-second
 55  * @raw_time:           Monotonic raw base time in timespec64 format
 56  * @cycle_interval:     Number of clock cycles in one NTP interval
 57  * @xtime_interval:     Number of clock shifted nano seconds in one NTP
 58  *                      interval.
 59  * @xtime_remainder:    Shifted nano seconds left over when rounding
 60  *                      @cycle_interval
 61  * @raw_interval:       Raw nano seconds accumulated per NTP interval.
 62  * @ntp_error:          Difference between accumulated time and NTP time in ntp
 63  *                      shifted nano seconds.
 64  * @ntp_error_shift:    Shift conversion between clock shifted nano seconds and
 65  *                      ntp shifted nano seconds.
 66  * @last_warning:       Warning ratelimiter (DEBUG_TIMEKEEPING)
 67  * @underflow_seen:     Underflow warning flag (DEBUG_TIMEKEEPING)
 68  * @overflow_seen:      Overflow warning flag (DEBUG_TIMEKEEPING)
 69  *
 70  * Note: For timespec(64) based interfaces wall_to_monotonic is what
 71  * we need to add to xtime (or xtime corrected for sub jiffie times)
 72  * to get to monotonic time.  Monotonic is pegged at zero at system
 73  * boot time, so wall_to_monotonic will be negative, however, we will
 74  * ALWAYS keep the tv_nsec part positive so we can use the usual
 75  * normalization.
 76  *
 77  * wall_to_monotonic is moved after resume from suspend for the
 78  * monotonic time not to jump. We need to add total_sleep_time to
 79  * wall_to_monotonic to get the real boot based time offset.
 80  *
 81  * wall_to_monotonic is no longer the boot time, getboottime must be
 82  * used instead.
 83  */
 84 struct timekeeper {
 85         struct tk_read_base     tkr_mono;
 86         struct tk_read_base     tkr_raw;
 87         u64                     xtime_sec;
 88         unsigned long           ktime_sec;
 89         struct timespec64       wall_to_monotonic;
 90         ktime_t                 offs_real;
 91         ktime_t                 offs_boot;
 92         ktime_t                 offs_tai;
 93         s32                     tai_offset;
 94         unsigned int            clock_was_set_seq;
 95         u8                      cs_was_changed_seq;
 96         ktime_t                 next_leap_ktime;
 97         struct timespec64       raw_time;
 98 
 99         /* The following members are for timekeeping internal use */
100         cycle_t                 cycle_interval;
101         u64                     xtime_interval;
102         s64                     xtime_remainder;
103         u32                     raw_interval;
104         /* The ntp_tick_length() value currently being used.
105          * This cached copy ensures we consistently apply the tick
106          * length for an entire tick, as ntp_tick_length may change
107          * mid-tick, and we don't want to apply that new value to
108          * the tick in progress.
109          */
110         u64                     ntp_tick;
111         /* Difference between accumulated time and NTP time in ntp
112          * shifted nano seconds. */
113         s64                     ntp_error;
114         u32                     ntp_error_shift;
115         u32                     ntp_err_mult;
116 #ifdef CONFIG_DEBUG_TIMEKEEPING
117         long                    last_warning;
118         /*
119          * These simple flag variables are managed
120          * without locks, which is racy, but they are
121          * ok since we don't really care about being
122          * super precise about how many events were
123          * seen, just that a problem was observed.
124          */
125         int                     underflow_seen;
126         int                     overflow_seen;
127 #endif
128 };
129 
130 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
131 
132 extern void update_vsyscall(struct timekeeper *tk);
133 extern void update_vsyscall_tz(void);
134 
135 #elif defined(CONFIG_GENERIC_TIME_VSYSCALL_OLD)
136 
137 extern void update_vsyscall_old(struct timespec *ts, struct timespec *wtm,
138                                 struct clocksource *c, u32 mult,
139                                 cycle_t cycle_last);
140 extern void update_vsyscall_tz(void);
141 
142 #else
143 
144 static inline void update_vsyscall(struct timekeeper *tk)
145 {
146 }
147 static inline void update_vsyscall_tz(void)
148 {
149 }
150 #endif
151 
152 #endif /* _LINUX_TIMEKEEPER_INTERNAL_H */
153 

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