[PATCH linux dev-4.10] ARM: dts: aspeed: Add gpio keys for power supply presence, ucd alert

[Joel Stanley]

On Thu, Jul 20, 2017 at 11:31 AM, Andrew Jeffery <andrew at aj.id.au> wrote:
>> > +
>> > +               ucd-alert {
>> > +                       label = "ucd-alert";
>> > +                       gpios = <&gpio ASPEED_GPIO(I, 2) GPIO_ACTIVE_LOW>;
>> > +                       linux,code = <ASPEED_GPIO(I, 2)>;
>> > +               };
>>
>> Andrew, are we sure this should be exposed to userspace? Is it
>> something that should be hooked up to the SMBus driver instead?
>
> I've looked at the relevant schematics and datasheets, and the GPIO of
> interest (I2) appears to be correct for the UCD alert. However, GPIOI2
> is *not* capable of being muxed as an SMBus Alert (SALT) line and
> therefore the alert will not be propagated to the I2C master. It
> appears we must handle it in userspace. Configuring it as GPIO key will
> give us an interrupt.

We discussed this today, and decided that we would look in to hooking
the GPIO up to the ucd driver. From there it will initiate the reading
of the fault registers, and allow the implementation of a poll()
response on the fault files in sysfs.

Cheers,

Joel