timecounter_init initializes the cyclecounter and sets the start time. Sometimes drivers using timecounter just want to update start time. This patch creates new function timecounter_reset that just resets the timecounter start time and associated state.
Suggested-by: Richard Cochran <richardcoch...@gmail.com> Signed-off-by: Sagar Arun Kamble <sagar.a.kam...@intel.com> Cc: Richard Cochran <richardcoch...@gmail.com> Cc: Chris Wilson <ch...@chris-wilson.co.uk> Cc: John Stultz <john.stu...@linaro.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Stephen Boyd <sb...@codeaurora.org> Cc: linux-kernel@vger.kernel.org --- include/linux/timecounter.h | 17 +++++++++++++++-- kernel/time/timecounter.c | 9 +++++++++ 2 files changed, 24 insertions(+), 2 deletions(-) diff --git a/include/linux/timecounter.h b/include/linux/timecounter.h index 59d3fd7..e0fd741 100644 --- a/include/linux/timecounter.h +++ b/include/linux/timecounter.h @@ -98,7 +98,7 @@ static inline void timecounter_adjtime(struct timecounter *tc, s64 delta) /** * timecounter_init - initialize a time counter - * @tc: Pointer to time counter which is to be initialized/reset + * @tc: Pointer to time counter which is to be initialized * @start_tstamp: Arbitrary initial time stamp. * * After this call the current cycle register (roughly) corresponds to @@ -131,8 +131,21 @@ extern void timecounter_initialize(struct timecounter *tc, u64 start_tstamp); /** + * timecounter_reset - reset a time counter + * @tc: Pointer to time counter which is to be reset + * @start_tstamp: Arbitrary initial time stamp. + * + * After this call the current cycle register (roughly) corresponds to + * the supplied time stamp. Every call to timecounter_read() increments + * the time stamp counter by the number of elapsed nanoseconds. + */ +extern void timecounter_reset(struct timecounter *tc, + u64 start_tstamp); + +/** * timecounter_read - return nanoseconds elapsed since timecounter_init() or - * timecounter_initialize() plus the initial time stamp + * timecounter_initialize() or timecounter_reset() plus + * the initial time stamp * @tc: Pointer to time counter. * * In other words, keeps track of time since the same epoch as diff --git a/kernel/time/timecounter.c b/kernel/time/timecounter.c index 6d915752..3f62fe0 100644 --- a/kernel/time/timecounter.c +++ b/kernel/time/timecounter.c @@ -47,6 +47,15 @@ void timecounter_initialize(struct timecounter *tc, } EXPORT_SYMBOL_GPL(timecounter_initialize); +void timecounter_reset(struct timecounter *tc, + u64 start_tstamp) +{ + tc->cycle_last = tc->cc.read(&tc->cc); + tc->nsec = start_tstamp; + tc->frac = 0; +} +EXPORT_SYMBOL_GPL(timecounter_reset); + /** * timecounter_read_delta - get nanoseconds since last call of this function * @tc: Pointer to time counter -- 1.9.1