[Intel-gfx] [PATCH 4/6] time: Expose current clocksource in use by timekeeping framework

[sourab.gupta at intel.com]

From: Sourab Gupta <sourab.gupta at intel.com>

For the drivers to be able to use the cross timestamp framework,
they need the information of current clocksource being used by the
kernel timekeeping. This is needed since the callback given by driver
into the get_device_system_crosststamp(), in order to synchronously read
the device time and system counter value, requires the knowledge of
the clocksource being used to read system counter value (as a part of
struct system_counterval_t).

Cc: John Stultz <john.stultz at linaro.org>
Cc: Thomas Gleixner <tglx at linutronix.de>
Signed-off-by: Sourab Gupta <sourab.gupta at intel.com>
---
 include/linux/timekeeping.h |  5 +++++
 kernel/time/timekeeping.c   | 12 ++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index d2e804e..d62bb0e 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -337,6 +337,11 @@ extern int get_device_system_crosststamp(
 			struct system_device_crosststamp *xtstamp);
 
 /*
+ * Get current clocksource used by system timekeeping framework
+ */
+struct clocksource *get_current_clocksource(void);
+
+/*
  * Simultaneously snapshot realtime and monotonic raw clocks
  */
 extern void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot);
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 95b258d..bd85d14 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1167,6 +1167,18 @@ int get_device_system_crosststamp(int (*get_time_fn)
 EXPORT_SYMBOL_GPL(get_device_system_crosststamp);
 
 /**
+ * get_current_clocksource - Returns the current clocksource in used by tk_core
+ *
+ */
+struct clocksource *get_current_clocksource(void)
+{
+	struct timekeeper *tk = &tk_core.timekeeper;
+
+	return tk->tkr_mono.clock;
+}
+EXPORT_SYMBOL_GPL(get_current_clocksource);
+
+/**
  * do_gettimeofday - Returns the time of day in a timeval
  * @tv:		pointer to the timeval to be set
  *
-- 
1.9.1