u-boot/doc/README.serial_multi
Tom Rini 65cc0e2a65 global: Move remaining CONFIG_SYS_* to CFG_SYS_*
The rest of the unmigrated CONFIG symbols in the CONFIG_SYS namespace do
not easily transition to Kconfig. In many cases they likely should come
from the device tree instead. Move these out of CONFIG namespace and in
to CFG namespace.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2022-12-05 16:06:08 -05:00

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The support for multiple serial interfaces as implemented is mainly
intended to allow for modem dial-in / dial-out while still being able
to use a serial console on a (different) serial port.
MPC8XX Specific
===============
At the moment, the ports must be split on a SMC and a SCC port on a
8xx processor; other configurations are not (yet) supported.
Support for hardware handshake has not been implemented yet (but is
in the works).
*) The default console depends on the keys pressed:
- SMC if keys not pressed (modem not enabled)
- SCC if keys pressed (modem enabled)
*) The console can be switched to SCC by any of the following commands:
setenv stdout serial_scc
setenv stdin serial_scc
setenv stderr serial_scc
*) The console can be switched to SMC by any of the following commands:
setenv stdout serial_smc
setenv stdin serial_smc
setenv stderr serial_smc
*) If a file descriptor is set to "serial" then the current serial device
will be used which, in turn, can be switched by above commands.
*) The baudrate is the same for all serial devices. But it can be switched
just after switching the console:
setenv sout serial_scc; setenv baudrate 38400
After that press 'enter' at the SCC console. Note that baudrates <38400
are not allowed on LWMON with watchdog enabled (see CFG_SYS_BAUDRATE_TABLE in
include/configs/lwmon.h).
PPC4XX Specific
===============
*) The default console is UART0
*) The console can be switched to UART1 by any of the following commands:
setenv stdout serial1
setenv stderr serial1
setenv stdin serial1
*) The console can be switched to UART0 by any of the following commands:
setenv stdout serial0
setenv stderr serial0
setenv stdin serial0