Arduino.h: Add digitalPinToInterrupt

- This does not seem to be present in ArduinoCoreAPI but defined for all
  Arduino boards (and microblocks has started using it).
- Also present in arduino docs.

Signed-off-by: Ayush Singh <[email protected]>

Author: Ayush1325

cores/arduino/Arduino.h

@@ -100,6 +100,8 @@ enum analogPins { DT_FOREACH_PROP_ELEM(DT_PATH(zephyr_user),
 void interrupts(void);
 void noInterrupts(void);
 
+int digitalPinToInterrupt(pin_size_t);
+
 #include <variant.h>
 #ifdef __cplusplus
 #include <zephyrPrint.h>

cores/arduino/zephyrCommon.cpp

@@ -480,3 +480,10 @@ void disableInterrupt(pin_size_t pinNumber) {
     pcb->handlers[BIT(arduino_pins[pinNumber].pin)].enabled = false;
   }
 }
+
+int digitalPinToInterrupt(pin_size_t pin)
+{
+  struct gpio_port_callback *pcb = find_gpio_port_callback(arduino_pins[pin].port);
+
+	return (pcb) ? pin : -1;
+}