AP_HAL: add attach_interrupt that takes a functor, not a AP_HAL::Proc

AP_HAL: add type-safety for interrupt types

AP_HAL: remove interrupt-low and interrupt-high, and interrupt-none

It is possible that the radio needs very tight timings - do not force
the use of the functor interface

AP_HAL: add detach_interrupt method

libraries/AP_HAL/GPIO.h

@@ -7,11 +7,6 @@
 #define HAL_GPIO_INPUT  0
 #define HAL_GPIO_OUTPUT 1
 #define HAL_GPIO_ALT    2
-#define HAL_GPIO_INTERRUPT_LOW 0
-#define HAL_GPIO_INTERRUPT_HIGH 1
-#define HAL_GPIO_INTERRUPT_FALLING 2
-#define HAL_GPIO_INTERRUPT_RISING 3
-#define HAL_GPIO_INTERRUPT_BOTH 4
 
 class AP_HAL::DigitalSource {
 public:
@@ -37,9 +32,36 @@ public:
     /* Alternative interface: */
     virtual AP_HAL::DigitalSource* channel(uint16_t n) = 0;
 
+    enum INTERRUPT_TRIGGER_TYPE {
+        INTERRUPT_NONE,
+        INTERRUPT_FALLING,
+        INTERRUPT_RISING,
+        INTERRUPT_BOTH,
+    };
+
     /* Interrupt interface: */
-    virtual bool    attach_interrupt(uint8_t interrupt_num, AP_HAL::Proc p,
-            uint8_t mode) = 0;
+    //                                ret , pin    , state,timestamp
+    // where:
+    //    ret indicates the functor must return void
+    //    pin is the pin which has triggered the interrupt
+    //    state is the new state of the pin
+    //    timestamp is the time in microseconds the interrupt occured
+    FUNCTOR_TYPEDEF(irq_handler_fn_t, void, uint8_t, bool, uint32_t);
+    virtual bool    attach_interrupt(uint8_t pin,
+                                     irq_handler_fn_t fn,
+                                     INTERRUPT_TRIGGER_TYPE mode) = 0;
+
+    virtual bool    attach_interrupt(uint8_t pin,
+                                     AP_HAL::Proc proc,
+                                     INTERRUPT_TRIGGER_TYPE mode) {
+        return false;
+    }
+    bool detach_interrupt(uint8_t pin) {
+        if (attach_interrupt(pin, (irq_handler_fn_t)nullptr, AP_HAL::GPIO::INTERRUPT_NONE)) {
+            return true;
+        }
+        return attach_interrupt(pin, (AP_HAL::Proc)nullptr, AP_HAL::GPIO::INTERRUPT_NONE);
+    }
 
     /* return true if USB cable is connected */
     virtual bool    usb_connected(void) = 0;