pps-rp1: A contemporary PPS Device Tree Overlay for the RPi 5

[josh-blake]

I've written up a dtoverlay that more or less exposes the bulk of the features available on the RPi 5 / RP1 GPIO Southbridge. It has the benefit of enabling the PPS Echo subsystem (mirrors the PPS signal out to another pin once the kernel has processed and timestamped). When this echo signal is captured by the GNSS External Int pin, it can report the round trip time which is then used as the correction factor. The overlay also exposes the Schmitt trigger subsystem on the RP1.

You can also enumerate multiple PPS sources with this overlay.

https://github.com/josh-blake/pps-rp1

[geerlingguy]

Neat! Any idea if this could be upstreamed to make RP1 PPS use much more flexible?

[josh-blake]

Have created a PR for the 6.18.y raspberrypi branch. Seems to pass all the tests etc., so hopefully ends up there soon!

[geerlingguy]

Just adding a link here too, for reference! raspberrypi/linux#7209

[josh-blake]

Good news. Has been merged and will hopefully show up in the next 6.18.y release.