>From Marc Zyngier <maz@xxxxxxxxxx>
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.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Signed-off-by: Jianyong Wu <jianyong.wu@xxxxxxx>
---
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
--
2.17.1
