From mboxrd@z Thu Jan 1 00:00:00 1970 From: swarren@wwwdotorg.org (Stephen Warren) Date: Thu, 16 May 2013 13:49:20 -0600 Subject: GPIO sysfs : set a wake source In-Reply-To: <87ip2ig1ez.fsf@free.fr> References: <87fvxwia0s.fsf@free.fr> <51926177.1050600@wwwdotorg.org> <87ip2ig1ez.fsf@free.fr> Message-ID: <51953840.9050106@wwwdotorg.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 05/16/2013 01:39 PM, Robert Jarzmik wrote: > Stephen Warren writes: > >> On 05/14/2013 03:29 AM, Linus Walleij wrote: >>> On Thu, May 9, 2013 at 2:59 PM, Robert Jarzmik wrote: >>> >>>> I was thinking on how to remove all "gpio_request()" from my board code >>>> (arch/arm/mach-pxa/mioa701.c). >>>> >>>> I have a small difficulty with the functionality provided by gpiolib in >>>> userspace. This is what I need : >>>> - define a gpio as an input >>>> - define this gpio to be an interrupt source >>>> - define this interrupt to be a wake-up source >>> >>> This sounds like trying to remove board code by moving it to userspace >>> and basically starting to implement stuff that belongs in the kernel >>> in userspace just because someone says we should get rid of board >>> files :-) > No, really, even it's true that it comes from someone asking me, now I have > though it a bit more through. > >>> Don't go down this path, let the kernel handle this kind of stuff. > Oh really, where ? > > Let me show you why it can't be a module. > In my case, I have a 2G modem connected to the soc : > - the modem and 1 SoC UART are connected (TX, RX, CTS, ...) > - the modem and SoC are connected through several gpios > - one or two control to power up and reset the modem > - one connected to the modem "ring" signal (the one I want a wakeup for). > > So I have no module to handle my modem : > - UART is handled by pxa-uart > - control/reset by gpiolib > - ring ... by nobody > > So my point is that this ring *should* be handled by gpiolib, just as any casual > input gpio. Moreover, the "wake-up" ability should be activable/deactivable on > wish by userspace. > >>> Instead figure out how to make the subsystems we have and the >>> device trees express what you want to do. > > As I said above, I don't think it's the way to go. I have *no* subsystem to > address. > Devicetree can't help in the toggle to "activate" or "deactivate" the wakeup > upon this GPIO, can it ? This sounds very similar to WiFi rfkill, although it's a MODEM not WiFi.