[PCIe] How to read/write PCIe Switch Configuration Space?

Here is a question, how to read/write PCIe Switch Configuration Space? We can see this picture first.

[PCIe] lspci command and the PCIe devices in my server

The following content is about my PCIe devices/drivers and the lspci command results.

$ cd /sys/bus/pci_express/drivers

$ ls -al

drwxr-xr-x 2 root root 0  7月  6 15:33 aer/

drwxr-xr-x 2 root root 0  7月  6 15:33 pciehp/

drwxr-xr-x 2 root root 0  7月  6 15:33 pcie_pme/