diff --git a/common/clock.c b/common/clock.c
index 2c5dd91..1090b60 100644
--- a/common/clock.c
+++ b/common/clock.c
@@ -213,6 +213,17 @@
 
 int init_clock(struct clocksource *cs)
 {
+	if (current_clock && cs->priority <= current_clock->priority)
+		return 0;
+
+	if (cs->init) {
+		int ret;
+
+		ret = cs->init(cs);
+		if (ret)
+			return ret;
+	}
+
 	current_clock = cs;
 	time_beginning = get_time_ns();
 
diff --git a/include/clock.h b/include/clock.h
index d65e404..5f2f53a 100644
--- a/include/clock.h
+++ b/include/clock.h
@@ -12,7 +12,8 @@
 	uint64_t	(*read)(void);
 	uint64_t	cycle_last;
 	uint64_t	mask;
-
+	int		priority;
+	int		(*init)(struct clocksource*);
 };
 
 static inline uint32_t cyc2ns(struct clocksource *cs, uint64_t cycles)