[PATCH arm/aspeed/ast2500 v1] ipmi: add an Aspeed KCS IPMI BMC driver

[Wang, Haiyue]

On 2018-01-17 07:06, Joel Stanley wrote:
> On Tue, Jan 16, 2018 at 2:59 PM, Corey Minyard <minyard at acm.org> wrote:
>> On 01/16/2018 05:43 AM, Haiyue Wang wrote:
>>> The KCS (Keyboard Controller Style) interface is used to perform in-band
>>> IPMI communication between a server host and its BMC (BaseBoard Management
>>> Controllers).
>>>
>>> This driver exposes the KCS interface on ASpeed SOCs (AST2400 and AST2500)
>>> as a character device. Such SOCs are commonly used as BMCs and this driver
>>> implements the BMC side of the KCS interface.
>>
>> I thought we were going to unify the BMC ioctl interface?  My preference
>> would be to
>> create a file named include/uapi/linux/ipmi-bmc.h and add the following:
>>
>> #define __IPMI_BMC_IOCTL_MAGIC    0xb1
>> #define IPMI_BMC_IOCTL_SMS_SET_ATN    _IO(__IPMI_BMC_IOCTL_MAGIC, 0x00)
>>
>> to make it the same as BT.  Then in bt-bmc.h, set BT_BMC_IOCTL_SMS_ATN to
>> IPMI_BMC_IOCTL_SMS_SET_ATN.  Then add the KCS ioctls in ipmi-bmc.h and
>> use that.  That way we stay backward compatible but we are unified.
>>
>> Since more KCS interfaces may come around, can you make the name more
>> specific?  (I made this same error on bt-bmc,c, it should probably be
>> renamed.)
> Yes, we had a group of openbmc people get together recently and spoke
> about this. Unfortunately Haiyue wasn't there (but other Intel BMC
> people were).
>
> We've got code coming from another BMC vendor who will use the same
> userspace API. The intention is to unify ASPEED's KCS and BT, along
> with Nuvoton's KCS and BT, as you outlined above.
Great design for common BMC code, thanks Joel & Corey.

Then we need to divide the kcs-bmc.c into two files, one (still 
kcs-bmc.c) is for handling IPMI KCS state
according to IPMI 2.0 specification, and also handing device misc 
operations; another file is called such
as aspeed-kcs-bmc.c which handles ast2500 kcs controller. So that 
Nuvoton can define nvvoton-kcs-bmc.c
low level API, and call the IPMI KCS function in kcs-bmc.c ?

How about this idea ? If it makes sense, I will change the code for 
review in patch v2.

> Cheers,
>
> Joel