linux/kernel/time/timecounter.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Based on clocksource code. See commit 74d23cc704d1
 */
#include <linux/export.h>
#include <linux/timecounter.h>

void timecounter_init(struct timecounter *tc,
		      const struct cyclecounter *cc,
		      u64 start_tstamp)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * timecounter_read_delta - get nanoseconds since last call of this function
 * @tc:         Pointer to time counter
 *
 * When the underlying cycle counter runs over, this will be handled
 * correctly as long as it does not run over more than once between
 * calls.
 *
 * The first call to this function for a new time counter initializes
 * the time tracking and returns an undefined result.
 */
static u64 timecounter_read_delta(struct timecounter *tc)
{ … }

u64 timecounter_read(struct timecounter *tc)
{ … }
EXPORT_SYMBOL_GPL(…);

/*
 * This is like cyclecounter_cyc2ns(), but it is used for computing a
 * time previous to the time stored in the cycle counter.
 */
static u64 cc_cyc2ns_backwards(const struct cyclecounter *cc,
			       u64 cycles, u64 mask, u64 frac)
{ … }

u64 timecounter_cyc2time(const struct timecounter *tc,
			 u64 cycle_tstamp)
{ … }
EXPORT_SYMBOL_GPL(…);