get_time_fn       271 include/linux/timekeeping.h 			int (*get_time_fn)(ktime_t *device_time,
get_time_fn      1117 kernel/time/timekeeping.c int get_device_system_crosststamp(int (*get_time_fn)
get_time_fn      1142 kernel/time/timekeeping.c 		ret = get_time_fn(&xtstamp->device, &system_counterval, ctx);