How to tuning usb

Hello

I have read “Jetson_TX2_USB2_Tuning_Guide_Application_Note.pdf” but I have questions

I don’t know how to set value of register in user space

example: page 9, step 3

Set PP (Port Power) in Disabled state by XUSB_XHCI_OP_PORTSC* bit [9] = 0.
       USB0: 0x03530450: XUSB_XHCI_OP_PORTSC_3
       USB1: 0x03530460: XUSB_XHCI_OP_PORTSC_4
       USB2: 0x03530470: XUSB_XHCI_OP_PORTSC_5

Could you provide command or tool to help me to do this?

Please refer to http://developer.nvidia.com/embedded/dlc/jetson-tx2-tx2i-usb-compliance-testing-guide