+What: /sys/class/ptp/ptpN/n_vclocks
+Date: May 2021
+Contact: Yangbo Lu <yangbo.lu@nxp.com>
+Description:
+ This file contains the number of virtual PTP clocks in
+ use. By default, the value is 0 meaning that only the
+ physical clock is in use. Setting the value creates
+ the corresponding number of virtual clocks and causes
+ the physical clock to become free running. Setting the
+ value back to 0 deletes the virtual clocks and
+ switches the physical clock back to normal, adjustable
+ operation.
+