local bus enumeration beyond a PCI device

Chris Packham
2024-04-18T00:24:14Z

Hi,

We've got a custom x86_64 based design that is using an ASIX9100 to
provide a PCI to local bus bridge. Attached to that local bus is an FPGA
which mostly provides some GPIOs accessed via registers on the local
bus. Right now we've got a custom driver that bundles everything
together so effectively we've got a PCI device that provides GPIOs.

But as things can change based on the FPGA program I'd like some
flexibility to treat it separately from the PCI bridge. So really I'd
like to have a PCI device driver for the ASIX9100 that provides a local
bus controller and a (platform?) driver for the FPGA that provides the
GPIOs where I can have different compatibles for the different
implementations.

Then in the ACPI overlay I'd have something like

Scope (\_SB.PCI0.D0B0)
{
Device (ASIX)
{
Name (_ADR, 0x0000)

Device (FPGA)
{
Name (_HID, "PRP0001")
Name (_DSD, Package ()
{
ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
Package ()
{
Package () {
"compatible", "my-platform-driver-for-fpga" },
}
})
}
}
}

Scope(\_SB)
{
Device(OTHR)
{
GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionInputOnly,
"\\_SB.PCI0.D0B0.ASIX.FPGA",) { 0 }
}
}

Is it even possible to register a host controller for another platform bus?

Thanks,
Chris