1 files changed, 55 insertions, 48 deletions

diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h
index 75bb8add78f5..97381997625b 100644
--- a/include/linux/timekeeper_internal.h
+++ b/include/linux/timekeeper_internal.h
@@ -10,80 +10,87 @@
 #include <linux/jiffies.h>
 #include <linux/time.h>
 
-/*
- * Structure holding internal timekeeping values.
- *
- * Note: wall_to_monotonic is what we need to add to xtime (or xtime
- * corrected for sub jiffie times) to get to monotonic time.
- * Monotonic is pegged at zero at system boot time, so
- * wall_to_monotonic will be negative, however, we will ALWAYS keep
- * the tv_nsec part positive so we can use the usual normalization.
+/**
+ * struct tk_read_base - base structure for timekeeping readout
+ * @clock:	Current clocksource used for timekeeping.
+ * @read:	Read function of @clock
+ * @mask:	Bitmask for two's complement subtraction of non 64bit clocks
+ * @cycle_last: @clock cycle value at last update
+ * @mult:	NTP adjusted multiplier for scaled math conversion
+ * @shift:	Shift value for scaled math conversion
+ * @xtime_nsec: Shifted (fractional) nano seconds offset for readout
+ * @base_mono:  ktime_t (nanoseconds) base time for readout
  *
- * wall_to_monotonic is moved after resume from suspend for the
- * monotonic time not to jump. To calculate the real boot time offset
- * we need to do offs_real - offs_boot.
+ * This struct has size 56 byte on 64 bit. Together with a seqcount it
+ * occupies a single 64byte cache line.
  *
- * - wall_to_monotonic is no longer the boot time, getboottime must be
- * used instead.
+ * The struct is separate from struct timekeeper as it is also used
+ * for a fast NMI safe accessor to clock monotonic.
  */
-struct timekeeper {
-	/* Current clocksource used for timekeeping. */
+struct tk_read_base {
 	struct clocksource	*clock;
-	/* Read function of @clock */
 	cycle_t			(*read)(struct clocksource *cs);
-	/* Bitmask for two's complement subtraction of non 64bit counters */
 	cycle_t			mask;
-	/* Last cycle value */
 	cycle_t			cycle_last;
-	/* NTP adjusted clock multiplier */
 	u32			mult;
-	/* The shift value of the current clocksource. */
 	u32			shift;
-	/* Clock shifted nano seconds */
 	u64			xtime_nsec;
-
-	/* Monotonic base time */
 	ktime_t			base_mono;
+};
 
-	/* Current CLOCK_REALTIME time in seconds */
+/**
+ * struct timekeeper - Structure holding internal timekeeping values.
+ * @tkr:		The readout base structure
+ * @xtime_sec:		Current CLOCK_REALTIME time in seconds
+ * @wall_to_monotonic:	CLOCK_REALTIME to CLOCK_MONOTONIC offset
+ * @offs_real:		Offset clock monotonic -> clock realtime
+ * @offs_boot:		Offset clock monotonic -> clock boottime
+ * @offs_tai:		Offset clock monotonic -> clock tai
+ * @tai_offset:		The current UTC to TAI offset in seconds
+ * @base_raw:		Monotonic raw base time in ktime_t format
+ * @raw_time:		Monotonic raw base time in timespec64 format
+ * @cycle_interval:	Number of clock cycles in one NTP interval
+ * @xtime_interval:	Number of clock shifted nano seconds in one NTP
+ *			interval.
+ * @xtime_remainder:	Shifted nano seconds left over when rounding
+ *			@cycle_interval
+ * @raw_interval:	Raw nano seconds accumulated per NTP interval.
+ * @ntp_error:		Difference between accumulated time and NTP time in ntp
+ *			shifted nano seconds.
+ * @ntp_error_shift:	Shift conversion between clock shifted nano seconds and
+ *			ntp shifted nano seconds.
+ *
+ * Note: For timespec(64) based interfaces wall_to_monotonic is what
+ * we need to add to xtime (or xtime corrected for sub jiffie times)
+ * to get to monotonic time.  Monotonic is pegged at zero at system
+ * boot time, so wall_to_monotonic will be negative, however, we will
+ * ALWAYS keep the tv_nsec part positive so we can use the usual
+ * normalization.
+ *
+ * wall_to_monotonic is moved after resume from suspend for the
+ * monotonic time not to jump. We need to add total_sleep_time to
+ * wall_to_monotonic to get the real boot based time offset.
+ *
+ * wall_to_monotonic is no longer the boot time, getboottime must be
+ * used instead.
+ */
+struct timekeeper {
+	struct tk_read_base	tkr;
 	u64			xtime_sec;
-	/* CLOCK_REALTIME to CLOCK_MONOTONIC offset */
 	struct timespec64	wall_to_monotonic;
-
-	/* Offset clock monotonic -> clock realtime */
 	ktime_t			offs_real;
-	/* Offset clock monotonic -> clock boottime */
 	ktime_t			offs_boot;
-	/* Offset clock monotonic -> clock tai */
 	ktime_t			offs_tai;
-
-	/* The current UTC to TAI offset in seconds */
 	s32			tai_offset;
-
-	/* Monotonic raw base time */
 	ktime_t			base_raw;
-
-	/* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */
 	struct timespec64	raw_time;
 
-	/* Number of clock cycles in one NTP interval. */
+	/* The following members are for timekeeping internal use */
 	cycle_t			cycle_interval;
-	/* Number of clock shifted nano seconds in one NTP interval. */
 	u64			xtime_interval;
-	/* shifted nano seconds left over when rounding cycle_interval */
 	s64			xtime_remainder;
-	/* Raw nano seconds accumulated per NTP interval. */
 	u32			raw_interval;
-
-	/*
-	 * Difference between accumulated time and NTP time in ntp
-	 * shifted nano seconds.
-	 */
 	s64			ntp_error;
-	/*
-	 * Shift conversion between clock shifted nano seconds and
-	 * ntp shifted nano seconds.
-	 */
 	u32			ntp_error_shift;
 };