Raspberry Pi5 - RP1 driver - RFC

[Stefan Wahren]

Hi Andrea,

i added Jeremy, because AFAIK he was deeply involved in ACPI
implementation of the RPi 4.

Am 11.06.24 um 17:39 schrieb Andrea della Porta:
> Hi,
> I'm on the verge of reworking the RP1 driver from downstream in order for it to be
> in good shape for upstream inclusion.
> 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 is an RFC about the correct approach to use
> in integrating the driver and registering the subdevices.
>
I cannot provide much input into the technical discussion, but i would
prefer an approach which works good with DT and ACPI.

Best regards
Stefan
>
> Link:
> - [1]: https://github.com/raspberrypi/linux/blob/rpi-6.6.y/arch/arm/boot/dts/broadcom/rp1.dtsi
> - [2]: https://github.com/raspberrypi/linux/blob/rpi-6.6.y/drivers/mfd/rp1.c
> - [3]: https://lpc.events/event/17/contributions/1421/attachments/1337/2680/LPC2023%20Non-discoverable%20devices%20in%20PCI.pdf
> - [4]: https://lore.kernel.org/lkml/20230419231155.GA899497-robh@kernel.org/t/
> - [5]: https://lore.kernel.org/lkml/Y862WTT03%2FJxXUG8@kroah.com/