linux-kernel - Re: Generic way for verifying GPIO wakeup capability

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Date:   Wed, 10 Jun 2020 23:28:47 +0530
From:   Pintu Agarwal <pintu.ping@...il.com>
To:     Kernelnewbies <kernelnewbies@...nelnewbies.org>,
        open list <linux-kernel@...r.kernel.org>,
        linux-pm@...r.kernel.org,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>, linux-gpio@...r.kernel.org,
        zonque@...il.com, sergiosiena@...il.com
Subject: Re: Generic way for verifying GPIO wakeup capability

On Tue, 9 Jun 2020 at 23:06, Pintu Agarwal <pintu.ping@...il.com> wrote:
>
> Hi All,
>
> I am looking for ways to wakeup any devices (from sleep) using any
> arbitrary gpio wakeup method in a generic way (either from user space
> or kernel space) that should work on any kernel version (starting from
> 4.14 onwards).
>
> What are the options available right now ?
> I wanted to experiment with all of them and decide which is best for us.
>
> Is /sys/class/gpio/ method still valid with the latest kernel ?
> Or is there any other method to do it from user space ?
>
> One option I know is to use enable/disable_irq_wake() API from kernel
> driver suspend/resume path.
> Just like this:
> https://lwn.net/Articles/569027/
>
> But this requires an additional kernel driver and device-tree changes
> for each gpio wakeup, which the end-user needs to implement on their
> own.
>
> Is there any other existing generic mechanism?
>

https://embeddedbits.org/new-linux-kernel-gpio-user-space-interface/

Is it possible to achieve this using this new interface ?

And I think another option is to use gpio-keys defined in device-tree.
Will this method work for any wake-capable gpio ?
How to verify this for any arbitrary gpio ?