PCI_XHCI_INTEL_XUSB2PR
pci_conf_write(psc->sc_pc, psc->sc_tag, PCI_XHCI_INTEL_XUSB2PR, val);
val = pci_conf_read(psc->sc_pc, psc->sc_tag, PCI_XHCI_INTEL_XUSB2PR);