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_mono:  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 accessor to clock monotonic.
  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_mono;
  39 };
  40
  41 /**
  42  * struct timekeeper - Structure holding internal timekeeping values.
  43  * @tkr:                The readout base structure
  44  * @xtime_sec:          Current CLOCK_REALTIME time in seconds
  45  * @wall_to_monotonic:  CLOCK_REALTIME to CLOCK_MONOTONIC offset
  46  * @offs_real:          Offset clock monotonic -> clock realtime
  47  * @offs_boot:          Offset clock monotonic -> clock boottime
  48  * @offs_tai:           Offset clock monotonic -> clock tai
  49  * @tai_offset:         The current UTC to TAI offset in seconds
  50  * @base_raw:           Monotonic raw base time in ktime_t format
  51  * @raw_time:           Monotonic raw base time in timespec64 format
  52  * @cycle_interval:     Number of clock cycles in one NTP interval
  53  * @xtime_interval:     Number of clock shifted nano seconds in one NTP
  54  *                      interval.
  55  * @xtime_remainder:    Shifted nano seconds left over when rounding
  56  *                      @cycle_interval
  57  * @raw_interval:       Raw nano seconds accumulated per NTP interval.
  58  * @ntp_error:          Difference between accumulated time and NTP time in ntp
  59  *                      shifted nano seconds.
  60  * @ntp_error_shift:    Shift conversion between clock shifted nano seconds and
  61  *                      ntp shifted nano seconds.
  62  *
  63  * Note: For timespec(64) based interfaces wall_to_monotonic is what
  64  * we need to add to xtime (or xtime corrected for sub jiffie times)
  65  * to get to monotonic time.  Monotonic is pegged at zero at system
  66  * boot time, so wall_to_monotonic will be negative, however, we will
  67  * ALWAYS keep the tv_nsec part positive so we can use the usual
  68  * normalization.
  69  *
  70  * wall_to_monotonic is moved after resume from suspend for the
  71  * monotonic time not to jump. We need to add total_sleep_time to
  72  * wall_to_monotonic to get the real boot based time offset.
  73  *
  74  * wall_to_monotonic is no longer the boot time, getboottime must be
  75  * used instead.
  76  */
  77 struct timekeeper {
  78         struct tk_read_base     tkr;
  79         u64                     xtime_sec;
  80         struct timespec64       wall_to_monotonic;
  81         ktime_t                 offs_real;
  82         ktime_t                 offs_boot;
  83         ktime_t                 offs_tai;
  84         s32                     tai_offset;
  85         ktime_t                 base_raw;
  86         struct timespec64       raw_time;
  87
  88         /* The following members are for timekeeping internal use */
  89         cycle_t                 cycle_interval;
  90         u64                     xtime_interval;
  91         s64                     xtime_remainder;
  92         u32                     raw_interval;
  93         /* The ntp_tick_length() value currently being used.
  94          * This cached copy ensures we consistently apply the tick
  95          * length for an entire tick, as ntp_tick_length may change
  96          * mid-tick, and we don't want to apply that new value to
  97          * the tick in progress.
  98          */
  99         u64                     ntp_tick;
 100         /* Difference between accumulated time and NTP time in ntp
 101          * shifted nano seconds. */
 102         s64                     ntp_error;
 103         u32                     ntp_error_shift;
 104         u32                     ntp_err_mult;
 105 };
 106
 107 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
 108
 109 extern void update_vsyscall(struct timekeeper *tk);
 110 extern void update_vsyscall_tz(void);
 111
 112 #elif defined(CONFIG_GENERIC_TIME_VSYSCALL_OLD)
 113
 114 extern void update_vsyscall_old(struct timespec *ts, struct timespec *wtm,
 115                                 struct clocksource *c, u32 mult,
 116                                 cycle_t cycle_last);
 117 extern void update_vsyscall_tz(void);
 118
 119 #else
 120
 121 static inline void update_vsyscall(struct timekeeper *tk)
 122 {
 123 }
 124 static inline void update_vsyscall_tz(void)
 125 {
 126 }
 127 #endif
 128
 129 #endif /* _LINUX_TIMEKEEPER_INTERNAL_H */