In which file enumeration of PCIe devices is located in Linux kernel for ARM based system?

Question

I am working to develop PCIe drivers for a custom ARM based platform. As a starting point I have started to look into Linux kernel 4.15.9 code. I am unable to locate the relevant PCIe driver files. In particular I am interested in PCIe device enumeration and configuration. Any help in this regard would be appreciated.

Answer 1

PCIe driver code is divided in 4 section.

1 - PCIe subsystem code

This is the generic PCIe subsystem code which takes care of Bus scan, MSI allocation, BAR allocation, etc.

Path - driver/pci/*

2 - PCIe host controller IP generic code

This is specific to the host controller. That means for a certain host in a platform, PCIe subsystem will communicate via the APIs provided by this code.

Path - drivers/pci/dwc/*
Example - DWC host
NOTE - Not all controller manufacturer has a separate folder like DWC (Synopsys).

3 - PCIe host controller initialization platform specific code

This is specific to the PCIe IP and it will be specific for a SoC. Every SoC will have their own chip specific code to initialize the controller. So the APIs in this part will be used by the "PCIe host generic code"

Path - drivers/pci/host/*

4 - PCIe capabilities

This code segment contain capabilities processing like AER, DPC. ASPM, etc.

Path - drivers/pci/pcie/*