How to debug and monitor the power management?

I want to track a problem which is likely caused by a bug in the power management.
How can I get verbose information on the power management activities?

I am looking for a log functionality which can show things like

2020-11-22 12:00:23 /dev/eth0: Set sleepmode 2, 20 mW due to inactivity
2020-11-22 12:00:34 /dev/eth0: set powermode 1, 50 mW woke up by pid 1233