From: "Christopher S. Hall" <christopher.s.h...@intel.com>
In the current timekeeping code there isn't any interface to
atomically capture the current relationship between the system counter
and system time. ktime_get_snapshot() returns this triple (counter,
monotonic raw, realtime) in the system_time_snapshot struct.
Cc: Prarit Bhargava <pra...@redhat.com>
Cc: Richard Cochran <richardcoch...@gmail.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Andy Lutomirski <l...@amacapital.net>
Cc: kevin.b.stan...@intel.com
Cc: kevin.j.cla...@intel.com
Cc: h...@zytor.com
Cc: jeffrey.t.kirs...@intel.com
Cc: netdev@vger.kernel.org
Reviewed-by: Thomas Gleixner <t...@linutronix.de>
Signed-off-by: Christopher S. Hall <christopher.s.h...@intel.com>
[jstultz: Moved structure definitions around to clean things up,
fixed cycles_t/cycle_t confusion.]
Signed-off-by: John Stultz <john.stu...@linaro.org>
---
include/linux/timekeeping.h | 18 ++++++++++++++++++
kernel/time/timekeeping.c | 30 ++++++++++++++++++++++++++++++
2 files changed, 48 insertions(+)
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index ec89d84..7817591 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -267,6 +267,24 @@ extern void ktime_get_raw_and_real_ts64(struct timespec64
*ts_raw,
struct timespec64 *ts_real);
/*
+ * struct system_time_snapshot - simultaneous raw/real time capture with
+ * counter value
+ * @cycles: Clocksource counter value to produce the system times
+ * @real: Realtime system time
+ * @raw: Monotonic raw system time
+ */
+struct system_time_snapshot {
+ cycle_t cycles;
+ ktime_t real;
+ ktime_t raw;
+};
+
+/*
+ * Simultaneously snapshot realtime and monotonic raw clocks
+ */
+extern void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot);
+
+/*
* Persistent clock related interfaces
*/
extern int persistent_clock_is_local;
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 4243d28..89b4695 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -874,6 +874,36 @@ time64_t __ktime_get_real_seconds(void)
return tk->xtime_sec;
}
+/**
+ * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with
counter
+ * @systime_snapshot: pointer to struct receiving the system time snapshot
+ */
+void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
+{
+ struct timekeeper *tk = &tk_core.timekeeper;
+ unsigned long seq;
+ ktime_t base_raw;
+ ktime_t base_real;
+ s64 nsec_raw;
+ s64 nsec_real;
+ cycle_t now;
+
+ do {
+ seq = read_seqcount_begin(&tk_core.seq);
+
+ now = tk->tkr_mono.read(tk->tkr_mono.clock);
+ base_real = ktime_add(tk->tkr_mono.base,
+ tk_core.timekeeper.offs_real);
+ base_raw = tk->tkr_raw.base;
+ nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now);
+ nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now);
+ } while (read_seqcount_retry(&tk_core.seq, seq));
+
+ systime_snapshot->cycles = now;
+ systime_snapshot->real = ktime_add_ns(base_real, nsec_real);
+ systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw);
+}
+EXPORT_SYMBOL_GPL(ktime_get_snapshot);
#ifdef CONFIG_NTP_PPS
--
1.9.1
