common bmc mailbox driver

[Andrew Jeffery]

Hi Eugene,

On Thu, 10 May 2018, at 22:34, Eugene.Cho at dell.com wrote:
> Hey Cyril,
>    I was recently following your upstream submission attempt for the 
> aspeed mbox/mailbox, was wondering if there was been any progress since?

FYI Cyril's moved on from IBM and OpenBMC, and so may have lost some motivation here.

> 
> Reason I ask - is Nuvoton also has a "mailbox" for bmc<->host 
> communication, which does the same thing (shared memory + interrupts 
> both ways), and was wondering if we could just have 1 driver for both, 
> instead 2 separate drivers.
> 
> Glancing at the aspeed driver, only key difference I see is the setting 
> and handling the interrupt. Thoughts on this?

(Somewhat unfortunately) the ASPEED mailbox driver isn't upstream yet due to push-back from the upstream mailbox subsystem maintainer*. Similar to the misc driver it sounds like we should work together to get things moving.

* It turns out the mailbox subsystem as it stands doesn't fit our needs - it's written from the perspective of the host kernel communicating with some firmware black box on the other side of the mailbox, rather than the kernel of interest *being* the black box.

Andrew