Poll both PCA9535 I/O using one interrupt?

DenisS · July 5, 2022

Hi everybody,

In a project I'm working on, I've added two PCA9535 I/O expanders to use 32 additional inputs on my Nano Pi Neo.
I've connected the INT line from both multiplexers to the gpio11 interrupt pin on the Nano Pi Neo, and attached to that a pull-up resistor of 10k.
I've used interrupts before, but my question is how to poll both PCA9535 I/O using one interrupt?
my DTS when polling one (It works!):

/dts-v1/;
/plugin/;

/ {
compatible = "allwinner,sun4i-a10", "allwinner,sun7i-a20", "allwinner,sun8i-h3", "allwinner,sun50i-a64", "allwinner,sun50i-h5";

   fragment@0 {
       /* This fragment is required only if using interrupts */
       target = <&pio>;
       __overlay__ {
           pca9535_pin_irq: pca9535_pin_irq {
               pins = "PA11";
               function = "irq";
               bias-pull-up;
           };
       };
   };

   fragment@1 {
       target = <&i2c1>;
       __overlay__ {
           #address-cells = <1>;
           #size-cells = <0>;
           pca9535@20 {
               compatible = "nxp,pca9535";
               reg = <0x20>;
               status = "okay";
               gpio-controller;
               #gpio-cells = <2>;
               gpio-line-names = "DI1", "DI2", "DI3", "DI4", "DI5", "DI6", "DI7", "DI8", "DI9", "DI10", "DI11", "DI12", "DI13", "DI14", "DI15", "DI16";
               /* Below are optional properties for supporting interrupts */
               interrupt-controller;
               #interrupt-cells = <2>;
               interrupt-parent = <&pio>;
               interrupts = <0 11 2>; /* PA11 IRQ_TYPE_EDGE_FALLING */
               pinctrl-names = "default";
               pinctrl-0 = <&pca9535_pin_irq>;
           };
       };
   };