PREAD4
PWRITE4((bst), (bsh), (reg), PREAD4((bst), (bsh), (reg)) | (bits))
PWRITE4((bst), (bsh), (reg), PREAD4((bst), (bsh), (reg)) & ~(bits))
uint32_t stat = PREAD4(bst, bsh, PCIE_PORT_LINK_STAT);
stat = PREAD4(bst, bsh, PCIE_PORT_STAT);
stat = PREAD4(bst, bsh, PCIE_PORT_LINK_STAT);
stat = PREAD4(pi, PL011COM_MIS);
msr = PREAD4(pi, PL01XCOM_FR);
sc->sc_msr = PREAD4(pi, PL01XCOM_FR);