GPIO Centralized Control Daemon

[Patrick Venture]

On Thu, Sep 14, 2017 at 3:29 PM, Rick Altherr <raltherr at google.com> wrote:

> When you do this, please use the gpio chardev interface instead of sysfs.
> Ask me for details if you aren't familiar.
>

I'm familiar with it.  I've heard they're phasing out sysfs gpio.


>
> On Thu, Sep 14, 2017 at 3:02 PM, Patrick Venture <venture at google.com>
> wrote:
>
>> I apologize if this already exists or is in the works.
>>
>> I propose we create a daemon that centralizes userspace GPIO access.
>>
>> From a high level, the daemon will implement interfaces to export or
>> unexport GPIOs.  Each GPIO exported will exist on the dbus:
>>
>> /xyz/openbmc_project/gpio/53 and implement an interface with the
>> following properties:
>> value, direction, active_low, etc.
>>
>> Some doubts, should the gpio name on the dbus be the relative name (53),
>> should it be the system specific name (G5) or the absolute name?  I'm
>> thinking the relative name and let the daemon handle internalizing the
>> adjustment from relative to absolute.
>>
>> I'm working on adding GPIO support within phosphor-hwmon so that I can
>> access a voltage sensor that's gated by a GPIO, and I know there have been
>> conversations and implementations of this for IPMI OEM -- and I think it
>> could easily be centralized.
>>
>> Thoughts?
>>
>> Patrick
>>
>
>
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