extres/phy: Add phy_set_mode method

[manu]

Summary

Some phy driver can have different mode, add a method interface to switch between them.
For now only usb mode are defined.

Test Plan

Part of a bigger patch : https://github.com/evadot/freebsd/tree/pinebook

[mmel]

Manu,
can you, please, subclass phy to USB specialized variant (say phyusb or usbphy)? You can use clk (clkdiv, clkmux ...) as template. We should implement lots of USB OTG related function here. VBUS voltage and over-current detection, ID pin status change interrupt, OTG state machine and I thing that should use proper layering from beginning.
If you too busy for this, I can implement (empty) subclass in next 2-3 days.

[manu]

In D17750#379506, @mmel wrote:

Manu,
can you, please, subclass phy to USB specialized variant (say phyusb or usbphy)? You can use clk (clkdiv, clkmux ...) as template. We should implement lots of USB OTG related function here. VBUS voltage and over-current detection, ID pin status change interrupt, OTG state machine and I thing that should use proper layering from beginning.
If you too busy for this, I can implement (empty) subclass in next 2-3 days.

Sure, I see what you mean.
I'll do that but probably more next week, won't have time this week.
Thanks