subsys: greybus: can adc be supported?

[anujdeshpande]

Are there plans to add ADC support? I see in the Greybus spec, in Chapter 11 Bridged PHY Connection Protocols that there is no mention of ADC. Is this something that would first be added to Greybus on the host, before considering that here?

[cfriedt]

@anujdeshpande
It doesn't seem like there is currently any ADC support in the spec, but I agree - that would be super useful. Have you asked about it on the mailing list?

[anujdeshpande]

@cfriedt https://lists.linaro.org/pipermail/greybus-dev/2021-May/001376.html

Greg said he'd be open to accepting patches around this - but there's no recommended way to go about this at the moment

[cfriedt]

@anujdeshpande - it looks as though there are occasional Greybus patches for Linux on the Greybus mailing list.

Based on Greg's feedback, I would say

1. Add a device class in Linux for ADC's. This will likely be the most difficult part, as there are a huge range of options and capabilities to look at to cover various vendor silicon. Hopefully a lot can be borrowed from IIO. This may take a very long time, so by all means use your prototype in production.
2. Propose a change to the Greybus spec accompanied by a proof of concept for the upstream project ara / nuttx code as well as some tests (tests could use gbsim, but you might be able to find a more creative solution). The spec / protocol changes should be simple enough that every ADC could share a common interface. Again, processes take time, so by all means use your prototype in production.
3. Would be great if you could eventually make a PR here 😉

It's really exciting to see some action happening around Greybus. I'm tempted to make some t-shirts and swag, free of course to those who can show git commit hashes!!