On Thursday 24 February 2011, 11:26:21 Ferenc Wagner wrote: > Alexander Stein <alexander.stein@xxxxxxxxxxxxxxxxxxxxx> writes: > > I'm just wondering which existing input driver I can choose to use an > > GPIO connected switch. The switch I'm talking about is connected via 3 > > (interruptable) GPIOs and those GPIOs can be inverted. > > Hi, > > How is the switch connected to the three GPIO inputs? > > > I think gpio-keys is wrong as they will generate events on each state > > change. Note: The switch is likely to bounce > > The gpio-keys driver has debouncing support. > > > and the current GPIO state might be invalid (all 3 GPIOs are 0). > > Why is this state invalid? > > > I also think gpio-keys can't make sure only one switch state is currently > > present. So I may get a current state 1 on 2 or more GPIOs which is > > obviously wrong. > > Sorry, I don't understand this. > > > My use case is the userspace polls the current switch state if it needs > > to know. > > EVIOCGKEY or EVIOCGSW ioctl, perhaps? You can make it three keys or > switches in the driver, and put the validation logic into user space... > > > Do you have any suggestions which driver to use or even write? > > Maybe it's just me, but I think you'd better give a clearer description > of your problem to get useful suggestions. Ok, let's give it a try. I have a sliding switch which has 3 positions, namely run, stop and reset. There can only be one position active at a time. None of them or more at the same time are invalid. At least none active GPIOs is possible due to the mechanical structure. Each position has a GPIO connected which affects the mounted pull-down or pull-up. e.g. run GPIO has a pull-down to GND and when the switch goes to run state the GPIO is raised to Vcc. The other positions are similar. The problem I have with EV_KEY or EV_SW is they have just binary states. Maybe I just should create a new driver which uses EV_ABS. Or is there already something similar? Alexander -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
