Adding compatible string to standard UART

[Ahmad Fatoum]

Hello Ayush,

On 29.08.23 18:58, Ayush Singh wrote:
> Hello everyone. I have been working on submitting my GSoC23 driver [1] to be merged upstream.
> 
> BeaglePlay has a specific UART that is connected to the CC1352 Co-processor. This UART is used to communicate with CC1352 co-processor. It is also used to flash stuff to this co-processor using bsl. Thus, it should be possible to disable it with an overlay and show it as a normal ttyS* device. Currently, the beagle kernel uses the following dts [3].
> 
> My driver uses this UART and thus I need to patch the devicetree. However, I am not too sure what I need to do to submit my device tree patch upstream. I read the Submitting Devicetree (DT) binding patches' doc [2], but I don't understand a few things:
> 
> 
> 1. Should I even be using device tree? Maybe there is a better method?

I haven't checked your links, but from your description, serdev might be what
you're after. In the DT that would be a child node of the existing serial
device.

> 2. Is there some naming convention? I was thinking of `beagle,cc1352-uart`

Not sure about the uart suffix. beagle,play-cc1352 sounds fine for a v1, I think.

> 
> 3. Do I need a documentation entry at `Documentation/devicetree/bindings`? If yes, should it go under serial?

Only if the cc1352 is itself a UART adapter, which doesn't appear to be the case.
Look what the function of the device has and choose the appropriate directory.
For coprocessors that have multiple functions, the main node is described
in mfd/ and the different functions in their respective directories.

> 
> 4. I think I am supposed to use YAML now and not txt?

Yes.

> 
> 5. What are the required fields in this doc file?

Just take a similar device as a template. See what's already in mfd/
and see what's similar to your usage.

Cheers,
Ahmad

> 
> 
> Ayush Singh
> 
> 
> 
> [1]: https://github.com/Ayush1325/linux/tree/gb-beagleplay
> 
> [2]: https://docs.kernel.org/devicetree/bindings/submitting-patches.html
> 
> [3]: https://git.beagleboard.org/beagleboard/linux/-/blob/v5.10.168-ti-arm64-r103/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts#L1206
> 
> 
> 
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