[Skiboot] [RFC PATCH] plat/qemu: Add BT device

[Cédric Le Goater]

On 11/12/2015 11:24 PM, Benjamin Herrenschmidt wrote:
> On Thu, 2015-11-12 at 18:23 +0100, Cédric Le Goater wrote:
>> This adds the BT device used to communicate with the BMC. This is
>> sufficient to handle IPMI messaging, power_downs and reboots the
>> way openpower systems do it.
>>
>> This patch needs to run on Ben's tree adding the support for the
>> PowerNV platform in qemu, plus some patches of mine. You will find
>> the resulting tree here :
>>
>> 	https://github.com/legoater/qemu/tree/powernv
>>
>> It's basic, probably a little too hacky, but it does provide enough
>> of a framework to handle communication with the BMC. Is it something
>> we want to add to qemu ? 
> 
> Thanks !
> 
> There's actually a pretty complete IPMI stack with BT etc... being
> written by Corey Minyard. He submitted it a while back, it didn't go in
> but he told me he plans to resubmit reasonably soon:
> 
> https://lists.gnu.org/archive/html/qemu-devel/2015-04/msg00641.html

That looks pretty mature. Impressive.


So I did some cookery today. I merged his patches and yours in this tree :

	https://github.com/legoater/qemu/tree/powernv-ipmi

Added the missing IPMI commands for pnv and the results looks promising. 
Just run a qemu with these devices :

	-device ipmi-bmc-sim,id=bmc0 -device isa-ipmi-bt,bmc=bmc0,irq=10

and skiboot/Linux will run fine. 

I did not port the SMS_ATN part. It should not be a big deal as all the 
framework is already in Corey's code.


As for my little BT thingy, I guess it is born obsolete. But it is small 
and does the job. May be we can keep it around for testing purpose until 
Corey merges his patchset ? Dunno, you tell me. I can put some efforts 
on both tree, Corey's tree and mine. It shouldn't be a problem.

Thanks,

C.