ioctl() forever?

You can't force people to write documentation. If you try, you just end up with something like the following:

> int FrobnicateSprocket(Sprocket *s)
> Frobnicates a sprocket.
>
> Arguments:
> s: The sprocket to frobnicate.
>
> Returns:
> Zero if no error, or nonzero and sets errno.
>
> Errno values:
> EPERM - Frobnicating this sprocket is not permitted.

IMHO if you're going to do something like this, it should be a machine-readable enumeration of commands, not a man page.