serial: ns16550: fix debug uart putc called before init
If _debug_uart_putc() is called before _debug_uart_init(), the
ns16550 debug uart driver hangs in a tight loop waiting for the
tx FIFO to get empty.
As this can happen via a printf sneaking in before the port calls
debug_uart_init(), let's rather ignore characters before the debug
uart is initialized.
This is done by reading the baudrate divisor and aborting if is zero.
Tested on socfpga_cyclone5_socrates.
Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
1 file changed