It seems that jiffies are just system ticks since the last reboot. This Stackoverflow question on the same topic except for Python seems to confirm that.

So, to get back to the "normal" timeformat, you would have to find the uptime of the system where these jiffies come from, and the tick rate of that system, and then divide the jiffie number by the tick rate to get the number of seconds since system reboot. If you add that to the time of last reboot, you get an epoch timestamp.

This seems to me to be a straightforward calculation, but I don't know of any module that implements it for you.