REG_DR
pl011_write(c, uap, REG_DR);
[REG_DR] = UART01x_DR,
return pl011_read(uap, REG_DR);
pl011_write(ch, uap, REG_DR);
pl011_read(uap, REG_DR);
pl011_write(ch, uap, REG_DR);
ch = pl011_read(uap, REG_DR) | UART_DUMMY_DR_RX;
pl011_reg_to_offset(uap, REG_DR),
pl011_reg_to_offset(uap, REG_DR),
pl011_write(uap->port.x_char, uap, REG_DR);
[REG_DR] = UART01x_DR,