package/linuxptp/linuxptp-system-clock.service

[Unit]
Description=Precision Time Protocol system clock synchronization
After=linuxptp.service

[Service]
ExecStart=/usr/sbin/phc2sys -s /dev/ptp0 -c CLOCK_REALTIME -w -S 1.0
Restart=always

[Install]
WantedBy=multi-user.target