hradio: Add driver to report RFKILL button press

[obiwac]

Summary

This driver only reports the RFKILL button presses for the time being.

This is needed for the "airplane" key on some Framework laptops.

Event: Halifax Hackathon 202606
Location: vishwin@'s car
Co-authored-by: Daniel Shaefer
Sponsored by: The FreeBSD Foundation
Sponsored by: Framework Computer Inc

Test Plan

See D56026 for previous revision and discussion.

Made into separate hradio(4) driver at wulf@'s request.

[ziaee]

share/man/man4/hradio.4

2–4

Probably meaningless nit: On the second page of style(9) it shows the copyright coming first. Sorry I didn't notice on the one that was complained about on the mailing list.

14

I wonder if we should do something like this to facilitate search accessibility? This does have a regression over the draft in omitting "radio", but I can't think of any ways that aren't clunky.

16–32

Would you be willing to use this? Everywhere else in the manual for many generations SYNOPSIS means "list the options, no prose". Currently we have around 200/500 driver manuals written this way, and I gave a talk on trying to consolidate around doing it that way last year at BSDCan, and I also posted uncontested on arch@ in January. I have an open revision to update our style guides to do it this way (D54586), and some parts of the FreeBSD documentation primer suggested to do so since long before I showed up.

39

We should mention something about how it reports the buttons so readers can know how to use it. In hgame(4) last year I wrote "and presents them to applications over the evdev interface".

41–46

This paragraph is usually for CAVEATS.

46

This section gets pulled verbatim into the hardware compatibility list, I wrote about it a little in style.mdoc(5).

50

Traditionally no period here, because this is not a sentence.

53

Traditionally we use no period here, I think the linter will complain also. All the hid drivers appear to also have xrefs back and forth to hidbus(4).