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Message-ID: <20230929023737.1610865-1-maheshb@google.com> Date: Thu, 28 Sep 2023 19:37:37 -0700 From: Mahesh Bandewar <maheshb@...gle.com> To: Netdev <netdev@...r.kernel.org>, Linux <linux-kernel@...r.kernel.org>, David Miller <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com> Cc: Jonathan Corbet <corbet@....net>, Don Hatchett <hatch@...gle.com>, Yuliang Li <yuliangli@...gle.com>, Mahesh Bandewar <mahesh@...dewar.net>, Mahesh Bandewar <maheshb@...gle.com>, John Stultz <jstultz@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, Stephen Boyd <sboyd@...nel.org>, Richard Cochran <richardcochran@...il.com> Subject: [PATCH 1/4] time: add ktime_get_cycles64() api add a method to retrieve raw cycles in the same fashion as there are ktime_get_* methods available for supported time-bases. The method continues using the 'struct timespec64' since the UAPI uses 'struct ptp_clock_time'. The caller can perform operation equivalent of timespec64_to_ns() to retrieve raw-cycles value. The precision loss because of this conversion should be none for 64 bit cycle counters and nominal at 96 bit counters (considering UAPI of s64 + u32 of 'struct ptp_clock_time). Signed-off-by: Mahesh Bandewar <maheshb@...gle.com> CC: John Stultz <jstultz@...gle.com> CC: Thomas Gleixner <tglx@...utronix.de> CC: Stephen Boyd <sboyd@...nel.org> CC: Richard Cochran <richardcochran@...il.com> CC: netdev@...r.kernel.org CC: linux-kernel@...r.kernel.org --- include/linux/timekeeping.h | 1 + kernel/time/timekeeping.c | 24 ++++++++++++++++++++++++ 2 files changed, 25 insertions(+) diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index fe1e467ba046..5537700ad113 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -43,6 +43,7 @@ extern void ktime_get_ts64(struct timespec64 *ts); extern void ktime_get_real_ts64(struct timespec64 *tv); extern void ktime_get_coarse_ts64(struct timespec64 *ts); extern void ktime_get_coarse_real_ts64(struct timespec64 *ts); +extern void ktime_get_cycles64(struct timespec64 *ts); void getboottime64(struct timespec64 *ts); diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 266d02809dbb..35d603d21bd5 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -989,6 +989,30 @@ void ktime_get_ts64(struct timespec64 *ts) } EXPORT_SYMBOL_GPL(ktime_get_ts64); +/** + * ktime_get_cycles64 - get the raw clock cycles in timespec64 format + * @ts: pointer to timespec variable + * + * This function converts the raw clock cycles into timespce64 format + * in the varibale pointed to by @ts + */ +void ktime_get_cycles64(struct timespec64 *ts) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned int seq; + u64 now; + + WARN_ON_ONCE(timekeeping_suspended); + + do { + seq = read_seqcount_begin(&tk_core.seq); + now = tk_clock_read(&tk->tkr_mono); + } while (read_seqcount_retry(&tk_core.seq, seq)); + + *ts = ns_to_timespec64(now); +} +EXPORT_SYMBOL_GPL(ktime_get_cycles64); + /** * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC * -- 2.42.0.582.g8ccd20d70d-goog
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