COM_REG_MSR
[COM_REG_MSR] = AUCOM_MSR,
[COM_REG_MSR] = MIO_UART_MSR_OFFSET,
[COM_REG_MSR] = RA_UART_MSR,
sc->sc_msr = CSR_READ_1(&sc->sc_regs, COM_REG_MSR);
msr = CSR_READ_1(regsp, COM_REG_MSR);
[COM_REG_MSR] = com_msr,