xref: /OK3568_Linux_fs/u-boot/doc/README.serial_multi (revision 4882a59341e53eb6f0b4789bf948001014eff981)
1*4882a593SmuzhiyunThe support for multiple serial interfaces as implemented is mainly
2*4882a593Smuzhiyunintended to allow for modem dial-in / dial-out while still being able
3*4882a593Smuzhiyunto use a serial console on a (different) serial port.
4*4882a593Smuzhiyun
5*4882a593SmuzhiyunMPC8XX Specific
6*4882a593Smuzhiyun===============
7*4882a593SmuzhiyunAt the moment, the ports must be split on a SMC and a SCC port  on  a
8*4882a593Smuzhiyun8xx processor; other configurations are not (yet) supported.
9*4882a593Smuzhiyun
10*4882a593SmuzhiyunSupport for hardware handshake has not been implemented yet (but is
11*4882a593Smuzhiyunin the works).
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun*) The default console depends on the keys pressed:
14*4882a593Smuzhiyun	- SMC if keys not pressed (modem not enabled)
15*4882a593Smuzhiyun	- SCC if keys pressed (modem enabled)
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun*) The console can be switched to SCC by any of the following commands:
18*4882a593Smuzhiyun
19*4882a593Smuzhiyun	setenv stdout serial_scc
20*4882a593Smuzhiyun	setenv stdin serial_scc
21*4882a593Smuzhiyun	setenv stderr serial_scc
22*4882a593Smuzhiyun
23*4882a593Smuzhiyun*) The console can be switched to SMC by any of the following commands:
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun	setenv stdout serial_smc
26*4882a593Smuzhiyun	setenv stdin serial_smc
27*4882a593Smuzhiyun	setenv stderr serial_smc
28*4882a593Smuzhiyun
29*4882a593Smuzhiyun*) If a file descriptor is set to "serial" then the current serial device
30*4882a593Smuzhiyunwill be used which, in turn, can be switched by above commands.
31*4882a593Smuzhiyun
32*4882a593Smuzhiyun*) The baudrate is the same for all serial devices. But it can be switched
33*4882a593Smuzhiyunjust after switching the console:
34*4882a593Smuzhiyun
35*4882a593Smuzhiyun	setenv sout serial_scc; setenv baudrate 38400
36*4882a593Smuzhiyun
37*4882a593SmuzhiyunAfter that press 'enter' at the SCC console. Note that baudrates <38400
38*4882a593Smuzhiyunare not allowed on LWMON with watchdog enabled (see CONFIG_SYS_BAUDRATE_TABLE in
39*4882a593Smuzhiyuninclude/configs/lwmon.h).
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun
42*4882a593SmuzhiyunPPC4XX Specific
43*4882a593Smuzhiyun===============
44*4882a593Smuzhiyun*) The default console is UART0
45*4882a593Smuzhiyun
46*4882a593Smuzhiyun*) The console can be switched to UART1 by any of the following commands:
47*4882a593Smuzhiyun	setenv stdout serial1
48*4882a593Smuzhiyun	setenv stderr serial1
49*4882a593Smuzhiyun	setenv stdin serial1
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun*) The console can be switched to UART0 by any of the following commands:
52*4882a593Smuzhiyun	setenv stdout serial0
53*4882a593Smuzhiyun	setenv stderr serial0
54*4882a593Smuzhiyun	setenv stdin serial0
55