On Tue, 2020-02-25 at 16:15 +0100, Andrew Lunn wrote:

Looking at it bottom up, is the WWAN device itself made up of multiple
devices? Are the TTYs separate drivers to the packet moving engines?

Possibly, yes, it depends a bit.

They have there own USB end points, and could just be standard CDC
ACM?

Yeah, for a lot of USB devices that's indeed the case.

driver/base/component.c could be useful for bringing together these
individual devices to form the whole WWAN device.

Huh, I was unaware of this, I'll take a look!

A very brief look suggests that it wants to have a driver for the whole
thing in the end, which isn't really true here, but perhaps we could
"make one up" and have that implement the userspace API. I need to take
a closer look, thanks for the pointer.

Plus you need to avoid confusion by not adding another "component
framework" which means something totally different to the existing
component framework.

:)

johannes