linux-kernel - Re: [REPOST RFC PATCH 0/3] New "gpio-poweroff" driver to turn off platform devices with GPIOs

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Message-ID: <D482A908-020C-43E0-ADFC-33AE213D7257@boeing.com>
Date:	Mon, 19 Dec 2011 10:56:41 -0600
From:	"Moffett, Kyle D" <Kyle.D.Moffett@...ing.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
CC:	Rob Herring <robherring2@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>, Liam Girdwood <lrg@...com>,
	Grant Likely <grant.likely@...retlab.ca>
Subject: Re: [REPOST RFC PATCH 0/3] New "gpio-poweroff" driver to turn off
 platform devices with GPIOs

On Dec 17, 2011, at 04:20, Mark Brown wrote:
> On Wed, Dec 14, 2011 at 02:34:37PM -0600, Moffett, Kyle D wrote:
>> On Dec 14, 2011, at 07:02, Mark Brown wrote:
>>> The regulator API in -next has DT bindings.
>> 
>> Based on the description of our hardware, is there a good way that I
>> can wire up gpio-regulator driver to our hardware with just the device
>> tree (and maybe one small board-specific function) to make it shut down
>> each domain in sequence at poweroff time? Otherwise I will just go back
>> to my custom board-specific function for GPIO-twiddling.
> 
> No, it's a very rare use case so there's nothing off the shelf.  But it
> should be straightfoward to write a device driver doing this.

Well, so that's what the "gpio-poweroff" driver I wrote is.  All it does
is hook into the device model and DT and provide various poweroff hooks
that poke GPIOs.

I still don't understand how the regulator API is supposed to help in my
particular case (whole-system poweroff).

Additional advice would be highly appreciated.

Cheers,
Kyle Moffett

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