UART Route setting

[Henbin Chang]

Hi Oskar,

Thanks your response.

In my machine design, the host uses AST2500 UART2 to implement console
redirection.
To make openbmc host consle/ipmi SOL workable, I use the 'local-tty =
ttyS2' setting and manually change the UART route (UART2<->UART3).

I found  VUART be used for host console after I checked some openpower
machines. Thus, they didn't meet this problem.

I also tried to look for any related discussion but got nothing.
To avoid any loss, I sent a mail to ask if any approach to change the UART
route under openbmc framework.

Currently, I add a hard code (modify HICRA regiser) in u-boot as the
workaround.

The suggestions you provided are good if the dynamic UART  route changing
is needed.

I may write a driver to handle the default UART route. It can be
enabled/disabled and get the the default UART route setting from machine dts,
and then modify the HICRA register.

Thanks.
Henbin.

2018-08-02 0:16 GMT+08:00 Oskar Senft <osk at google.com>:

> Hi Henbin
>
> It's funny that you ask, since I had just started to look into the same
> problem.
>
> I'd like to change the UART routing on an AST2500 when a client connects
> to the obmc-console-server. The use case is to dynamically connect the
> host's UART to a UART owned by the BMC.
>
> I was thinking of writing a kernel driver that would expose the config
> options from the HICRA register on AST2500 as /sys files. Each file
> represents the target UART1..5 and IO1..5. The file value represents the
> source UART1..5 and IO1..5. Not all combinations are supported by the
> Aspeed, so I'd add the necessary checks and error reporting into the code.
>
> An alternative would be to just use /dev/mem to do that, but my
> understanding is that default support for that is going away or has gone
> away.
>
> Oskar.
>
>
> ---------- Forwarded message ----------
>> From: Henbin Chang <henbinchang at gmail.com>
>> Date: Wed, Aug 1, 2018 at 12:11 AM
>> Subject: UART Route setting
>> To: OpenBMC Maillist <openbmc at lists.ozlabs.org>
>>
>>
>> Hi,
>>
>> Could anyone know how to modify UART Route setting through dts, driver
>> or other mechanism?
>>
>> Or I have to find a point to modify it e.g. board_init() in the u-boot.
>>
>> Thanks.
>>
>
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