On Wednesday 19 June 2013, Guenter Roeck wrote:
> I have been asked to explore options for adding ARINC 429 support [1]
> into the Linux kernel, primarily to support devices from Holt Integrated
> Circuits [2] (the request is unrelated to the chip manufacturer).
>
> ARINC429 is a protocol which is widely used in commercial airplanes.
>
> There are various chips supporting this protocol available, as well as
> out-of-tree Linux support. The drivers I have looked at implement it
> either as character device or misc device and typically pass raw receive
> data to userspace.
>
> I can see a number of options for going forward:
> 1) Implement as character device (or possibly misc device) and pass
> raw data to/from user space
> 1a) Just implement a driver for the specific chips
> 2b) Implement some kind of generic infrastructure
> 2) Implement as network driver with a new address family, similar to,
> say, AF_CAN.
>
> Any thoughts / suggestions which approach would be better and, most of all,
> which approach might have a better chance of being accepted upstream ?
Since this is a standard protocol, a driver that just supports a specific
chip (1a) would be the worst option IMHO.
A character device and a network protocol both sound reasonable, but
it really depends on the use cases:
* Does Linux act both as the sender and receiver, or do you want to
support just one of the cases (which?)?
* Would you expect to always just transfer a single 32-bit word, or
are there larger chunks of logically contigous data? What are typical
and maximum sizes for those?
* Would you expect the kernel to filter for specific data on the
receiver side?
* Would a user space receiver want to always see all data from one
sender, or only the latest word?
Arnd
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