How to add pcie-root-port and device behind it in C?

How to add pcie-root-port and device behind it in C?

[Marcin Juszkiewicz]

I was going through Arm (S)BSA tests run against sbsa-ref. Many of them 
check for presence of other cards than "Root Complex Integrated 
Endpoint" ones.

The "-device root-pcie-port" etc arguments can be used to add such ones 
but I was wondering how to add them directly in C code. Tried to find is 
there any example but looks like all systems use flat structure.

So the question is: How to add pcie-root-port and device behind it in C?

Something like those two arguments but in C:

-device pcie-root-port,id=JBHBE,slot=0,chassis=0
-device igb,bus=JBHBE

# lspci -tv
-[0000:00]-+-00.0  Red Hat, Inc. QEMU PCIe Host bridge
            +-01.0  Intel Corporation 82574L Gigabit Network Connection
            +-02.0  Device 1234:1111
            \-03.0-[01]----00.0  Intel Corporation 82576 Gigabit Network