| Message ID | 20190918080716.64242-4-jianyong.wu@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Enable ptp_kvm for arm64 | expand |
On 18/09/19 10:07, Jianyong Wu wrote: > From Marc Zyngier <maz@kernel.org> > A number of PTP drivers (such as ptp-kvm) are assuming what the > current clock source is, which could lead to interesting effects on > systems where the clocksource can change depending on external events. > > For this purpose, add a new API that retrives both the current > monotonic clock as well as its counter value. > > From Jianyong Wu: export this API then modules can use it. See review of patch 4. ktime_get_snapshot is even better for your needs, if I'm not mistaken. Paolo > Signed-off-by: Marc Zyngier <maz@kernel.org> > Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> > --- > include/linux/timekeeping.h | 3 +++ > kernel/time/timekeeping.c | 13 +++++++++++++ > 2 files changed, 16 insertions(+) > > diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h > index a8ab0f143ac4..a5389adaa8bc 100644 > --- a/include/linux/timekeeping.h > +++ b/include/linux/timekeeping.h > @@ -247,6 +247,9 @@ extern int get_device_system_crosststamp( > struct system_time_snapshot *history, > struct system_device_crosststamp *xtstamp); > > +/* Obtain current monotonic clock and its counter value */ > +extern void get_current_counterval(struct system_counterval_t *sc); > + > /* > * Simultaneously snapshot realtime and monotonic raw clocks > */ > diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c > index 44b726bab4bd..07a0969625b1 100644 > --- a/kernel/time/timekeeping.c > +++ b/kernel/time/timekeeping.c > @@ -1098,6 +1098,19 @@ static bool cycle_between(u64 before, u64 test, u64 after) > return false; > } > > +/** > + * get_current_counterval - Snapshot the current clocksource and counter value > + * @sc: Pointer to a struct containing the current clocksource and its value > + */ > +void get_current_counterval(struct system_counterval_t *sc) > +{ > + struct timekeeper *tk = &tk_core.timekeeper; > + > + sc->cs = READ_ONCE(tk->tkr_mono.clock); > + sc->cycles = sc->cs->read(sc->cs); > +} > +EXPORT_SYMBOL_GPL(get_current_counterval); > + > /** > * get_device_system_crosststamp - Synchronously capture system/device timestamp > * @get_time_fn: Callback to get simultaneous device time and >
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index a8ab0f143ac4..a5389adaa8bc 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -247,6 +247,9 @@ extern int get_device_system_crosststamp( struct system_time_snapshot *history, struct system_device_crosststamp *xtstamp); +/* Obtain current monotonic clock and its counter value */ +extern void get_current_counterval(struct system_counterval_t *sc); + /* * Simultaneously snapshot realtime and monotonic raw clocks */ diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 44b726bab4bd..07a0969625b1 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1098,6 +1098,19 @@ static bool cycle_between(u64 before, u64 test, u64 after) return false; } +/** + * get_current_counterval - Snapshot the current clocksource and counter value + * @sc: Pointer to a struct containing the current clocksource and its value + */ +void get_current_counterval(struct system_counterval_t *sc) +{ + struct timekeeper *tk = &tk_core.timekeeper; + + sc->cs = READ_ONCE(tk->tkr_mono.clock); + sc->cycles = sc->cs->read(sc->cs); +} +EXPORT_SYMBOL_GPL(get_current_counterval); + /** * get_device_system_crosststamp - Synchronously capture system/device timestamp * @get_time_fn: Callback to get simultaneous device time and