How to invoke pcie functions with nvme linux driver installed in device

I am new to linux device drivers.I am familiar with linux driver code for pcie and nvme. I have loaded linux nvme driver and able to send read, write command through nvme cli. With nvme driver loaded, is there a way to send pcie commads( change speed, lanes) to device. What are the changes to be done to existing nvme driver code? The main objective is to port bunch of pcie testcases to run in parallel with nvme read/writes