serial8250_early_in
status = serial8250_early_in(port, UART_LSR);
s[num_read++] = serial8250_early_in(port, UART_RX);
ier = serial8250_early_in(port, UART_IER);
c = serial8250_early_in(port, UART_LCR);
ier = serial8250_early_in(port, UART_IER);
status = serial8250_early_in(port, UART_LSR);