DLAB
outb(lcr | DLAB, port + LCR);
outb(c | DLAB, port + LCR);
outb(c & ~DLAB, port + LCR);
static_call(serial_out)(early_serial_base, LCR, c | DLAB);
static_call(serial_out)(early_serial_base, LCR, c & ~DLAB);