Linux Patches Work To Upstream Raspberry Pi's RP1 PCI Device Support

Andrea della Porta of SUSE has been working on upstreaming the Linux kernel support to boot the Raspberry Pi 5 on a mainline kernel. Over the past few months Andrea has posted a number of different patches derived in part from Raspberry Pi's downstream kernel code. The latest effort being pursued by the SUSE engineer is on upstreaming Raspberry Pi RP1 PCI device support using a DeviceTree overlay.

With the Raspberry Pi 5 there is the RP1 as an in-house I/O controller / chipset used for providing the MIPI camera input, display output, USB 2, USB 3, analog video output, Gigabit Ethernet MAC, and other I/O functionality for this single board computer.

Andrea della Porta explained with today's new patch series:

"RP1 is an MFD chipset that acts as a south-bridge PCIe endpoint sporting a pletora of subdevices (i.e. Ethernet, USB host controller, I2C, PWM, etc.) whose registers are all reachable starting from an offset from the BAR address. The main point here is that while the RP1 as an endpoint itself is discoverable via usual PCI enumeraiton, the devices it contains are not discoverable and must be declared e.g. via the devicetree.

This patchset is an attempt to provide a minimum infrastructure to allow the RP1 chipset to be discovered and perpherals it contains to be added from a devictree overlay loaded during RP1 PCI endpoint enumeration. Followup patches should add support for the several peripherals contained in RP1.

This work is based upon dowstream drivers code and the proposal from RH et al."

These patches also depend upon the still yet-to-be-upstreamed BCM2712 PCIe controller patches. We're quickly approaching one year since the release of the Raspberry Pi 5 in October and at this rate it's looking like by that point the mainline kernel will still not yet have full upstream support for this popular ARM64 SBC.