tree d6ab8dab8076d0dc5e7f7ad64b7d8dfb9be7a025
parent 6f38622d9d7078ba40f1997fd90d680b670578ea
author Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com> 1533841459 +0200
committer Simon Glass <sjg@chromium.org> 1542215788 -0800

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>