generic-uio driver dts node for external button 4 input

[stevers]

Working with a zybo-z7 (XC7Z010-1CLG400C) trying to register a uio driver over the button 4 (mio50) gpio connected to the PS.

The design already included a gpio module as: 

/ {
    amba: axi {
        gpio0: gpio@e000a000 {
            compatible = "xlnx,zynq-gpio-1.0";
            #gpio-cells = <2>;
            clocks = <&clkc 42>;
            gpio-controller;
            interrupt-controller;
            #interrupt-cells = <2>;
            interrupt-parent = <&intc>;
            interrupts = <0 20 4>;
            reg = <0xe000a000 0x1000>;
        };
    };
};

        
I have added the following btn_4 dts node in system-user.dtsi:

/ {

    chosen {
        bootargs = "console=ttyPS0,115200 earlyprintk uio_pdrv_genirq.of_id=generic-uio";
    };

    ...

    btn_4 {
    compatible ="generic-uio";
    interrupt-parent = <&gpio0>;
    // mio 50, rising edge
    interrupts = <50 1>;
    };
};

There kernel config includes:

CONFIG_UIO=y
CONFIG_UIO_PDRV_GENIRQ=y

On booting the device with the new uio node, I see the btn_4 registered in the interrupt table:

root@Petalinux-2022:~# cat /proc/interrupts 
           CPU0       CPU1  
...
 66:          0          0  zynq-gpio  50 Edge      btn_4
...

But after pressing the button I don't see the interrupt count increase in /proc/interrupts  
           CPU0       CPU1  
...
 66:          0          0  zynq-gpio  50 Edge      btn_4
...

Is there something incorrect about how the uio interrupt is configured for the new btn_4 node?

[Ionel]

Try using it as gpio. Export it, set as input direction and check it's value when pressed to see if it actualy works before using with generic-uio

[stevers]

Good suggestion lonel.

To test the PS side mio I successfully toggled the LED4 at mio 7. I exported the gpio at 905+7 = 912 as an output as below:

echo 912 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio912/direction
echo 1 > /sys/class/gpio/gpio912/value
echo 0 > /sys/class/gpio/gpio912/value

Not seeing an input chage at BTN4, and BTN5 mio mappings:

echo 955 > /sys/class/gpio/export
echo 956 > /sys/class/gpio/export
echo in > /sys/class/gpio/gpio955/direction
echo in > /sys/class/gpio/gpio956/direction

The following always return the same value when pressing the btn4 and btn5

cat /sys/class/gpio/gpio955/val
cat /sys/class/gpio/gpio956/val

Thanks 

Edited December 19, 2022 by stevers