In that case let me drop LEDs from v2 for now. The hardware is a single
bicolor LED (green/amber) with speed-based color selection (vendor firmware
does 10G=green, else amber). I don't immediately see an obvious way to express
that in the LED framework. If there's a good example to follow I'd appreciate
a pointer; otherwise I'll figure it out as a follow-up.

That is why asked about its capabilities.

The minimum you need for /sys/class/leds is to be able to turn the LED
on and off.

What sort of bicolor LED is it? 2 legs or three? Are green and amber
mutually exclusive, or can you control them independently? If they are
independent, then you can represent it as two LEDs. If the colours are
mutually exclusive its a different story.

Oh, unusual, there is a datasheet:

https://datasheet4u.com/pdf/1561522/BCM84891L.pdf

That is not like Broadcom.

The LED controller has what is needed to follow the normal way of
doing it. So please do drop this part of the patch. For examples, look
at any PHY driver which implements .led_brightness_set and the other
ops in struct phy_driver.

	Andrew