lpc reset questions

[Eugene.Cho at dell.com]

Thanks Joel. One more question - 

Are you aware of any ABI to notify User Space whenever a LPC reset occurs? I didn’t see anything... and I am unsure if this is something that only we/Dell needs...



-----Original Message-----
From: joel.stan at gmail.com [mailto:joel.stan at gmail.com] On Behalf Of Joel Stanley
Sent: Wednesday, June 6, 2018 3:38 AM
To: Cho, Eugene
Cc: OpenBMC Maillist
Subject: Re: lpc reset questions

Hello Eugene,

On 6 June 2018 at 01:58,  <Eugene.Cho at dell.com> wrote:
>    I was trying to follow the following submission  
> https://lkml.org/lkml/2018/2/19/12,
> so best I can tell is on Aspeed this "reset-simple driver" will just 
> take the UART out-of-reset, because Aspeed automatically puts the UART in reset on LPC-reset????
> Did I get that right?

At power on, the aspeed ties the reset of UART1 and UART2 to the LPC reset. I figure this is because they have a "SUART" mode, where host SIO accesses are used to program the BMC's UART directly from the host over the LPC.

This doesn't work for Linux on the BMC as it expects the device to be functional when it loads it's driver. Hence, the simple-reset driver pokes at the tied-to-LPC-reset bit, effectively taking the UART out of reset.

Cheers,

Joel