[PATCH v2 1/2] soc: aspeed: add BMC-side PCIe BMC device driver

[Grégoire Layet]

Hello Andrew,

Anirudh Srinivasan and I have found that IPMI over KCS using the
PCI worked with the stock ASPEED bmc driver (the bmc driver in the V1)
but not with the trimmed-down version in the V2. I have apparently removed
a bit too much from the V2 , but that's not what I want to focus on.

This brings back the question of where we should put the registers
configuration,
considering that two different functionalities depend on it.

> It is also possible to put the SCU initialisation on the
> 8250_aspeed_vuart driver
> directly. This could be activated with a specific flag added to VUART nodes
> ('pcie2vuart' for example) on the DeviceTree.

Similarly to this idea, we could include have the necessary configuration in the
'kcs_bmc_aspeed' driver. This could be activated using a similar flag
,such as 'pci2lpc'
or 'pci2kcs' directly. However, this would result in a lot of code
duplication for most
of the configuration.

The issue for me is that, two drivers configuring the same registers
is not a good idea.
I don't know how to do this the proper way.

I wanted to add this information because it could influence the move to a
bmc_device driver that configures both VUART and KCS, over PCI.
This would be similar to the V2 bmc driver, and I fix the KCS bug.

Thanks,
Grégoire