include/linux/timekeeper_internal.h

   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 */