gpio-pps on pi4

Are there instructions on how to use gpio-pps on a pi4?
Or a working gpio-pps.dtbo file I can use?
Ideally without having to recompile anything.

Instructions in /sys/contrib/device-tree/Bindings/pps/pps-gpio.txt
are not clear to me. 

I suppose I can try to create one using the following as a template
and fix things up....
https://github.com/raspberrypi/linux/blob/rpi-5.10.y/arch/arm/boot/dts/overlays/pps-gpio-overlay.dts

And is there a way to mmap the gpio address space?

Thanks!