Query last reported event state

Query last reported event state

[Daniel Mack]

Hi,

is there a way to query the last state an input device reported,
preferably even for a special key mask? When a button is pressed and a
userspace application is started, it should be able to figure out the
current state, especially because those GPIO signals are likely
connected to other peripherals to report arbitrary events in the system.
Is there any such framework for that purpose?

A somewhat related topic is: Looking at the gpio_keys.c for example, I
think there should be code that reports an event from probe() when the
configured GPIO is not in its 'inactive' state, otherwise it will loose
the first key-up event, right?

Thanks,
Daniel

Re: Query last reported event state

[Mika Westerberg]

Hi Daniel,

On Tue, Nov 24, 2009 at 06:33:56PM +0100, Daniel Mack wrote:
> Hi,
> 
> is there a way to query the last state an input device reported,
> preferably even for a special key mask? When a button is pressed and a
> userspace application is started, it should be able to figure out the
> current state, especially because those GPIO signals are likely
> connected to other peripherals to report arbitrary events in the system.
> Is there any such framework for that purpose?

Not sure whether this helps, but you can look <linux/input.h> and
check what ioctl()s it provides for this purpose. At least there
seems to be:
	EVIOCGKEY - get global keystate
	EVIOCGSW - get all switch states
	EVIOCGBIT - get event bits

Maybe you can use some of these to query current status of input events.

MW

Re: Query last reported event state

[Dmitry Torokhov]

On Tue, Nov 24, 2009 at 09:57:29PM +0200, Mika Westerberg wrote:
> Hi Daniel,
> 
> On Tue, Nov 24, 2009 at 06:33:56PM +0100, Daniel Mack wrote:
> > Hi,
> > 
> > is there a way to query the last state an input device reported,
> > preferably even for a special key mask? When a button is pressed and a
> > userspace application is started, it should be able to figure out the
> > current state, especially because those GPIO signals are likely
> > connected to other peripherals to report arbitrary events in the system.
> > Is there any such framework for that purpose?
> 
> Not sure whether this helps, but you can look <linux/input.h> and
> check what ioctl()s it provides for this purpose. At least there
> seems to be:
> 	EVIOCGKEY - get global keystate
> 	EVIOCGSW - get all switch states
> 	EVIOCGBIT - get event bits
> 
> Maybe you can use some of these to query current status of input events.

This is correct. The first 2 ioctls are there so userspace can get the
current state of input device. The last ioctl is to query capabilities,
not the state though.

-- 
Dmitry