Driver for Raspberry Pi 4 PCI-express controller

[Robert Crowston]

A patch adding support for the pcie controller on the bcm2838 chip is available here:

https://github.com/RobCrowston/freebsd/commit/3626d1f774a72f2f77feedf100429d0a23ac50c8.patch

This is still in development, but it is ready for wider testing.

I have tested this patch on three different Pi4s I have, including a 2 GB and a 4 GB model. For the most part HIDs like keyboards and mice are reliable, but data transfers from mass storage devices can sometimes, though not reproducibly, cause the xHCI controller to reset. I have only tested it against the soldered-on xHCI chip; if anyone has desoldered it and replaced it with a pci-pci bridge, that would be interesting to hear about.

Before I submit this to phabricator, assuming there is interest, I would be interested to hear others' experiences with it, or indeed any other feedback.