Query regarding Phy loopback support

[Hariprasad Kelam]

We're looking for a standard way to configure PHY loopback on a network 
interface using common Linux tools like ethtool, ip, or devlink.

Currently, ethtool -k eth0 loopback on enables a generic loopback, but it 
doesn't specify if it's an internal, external, or PHY loopback. 
Need suggestions to implement this feature in a standard way.