Refactored Interruptable GPIO codes

Created two new Interface and hid implementation details as much as possible.

gpio.go

@@ -23,9 +23,13 @@ const (
 	High
 )
 
+// Edge trigger for GPIO Interrupt
 type Edge string
+
+// IRQ event function definition
 type IRQEvent func(pin DigitalPin)
 
+// Available Edge trigger for Interrupt
 const (
 	EdgeNone    Edge = "none"
 	EdgeRising  Edge = "rising"
@@ -33,8 +37,25 @@ const (
 	EdgeBoth    Edge = "both"
 )
 
+// InterruptPin implements access to a Interruptable capable GPIO pin.
+type InterruptPin interface {
+	// return file handler for GPIO
+	Fd() int
+
+	// Start watching this pin for interrupt
+	Watch(edge Edge, callback IRQEvent) error
+
+	// Stop watching this pin for interrupt
+	StopWatching() error
+
+	// Signal that an Interrupt has happened
+	Signal()
+}
+
 // DigitalPin implements access to a digital IO capable GPIO pin.
 type DigitalPin interface {
+	InterruptPin
+
 	// N returns the logical GPIO number.
 	N() int
 
@@ -60,11 +81,6 @@ type DigitalPin interface {
 	// PullDown pulls the pin down.
 	PullDown() error
 
-	Watch(edge Edge, callback IRQEvent) error
-	StopWatching() error
-
-	Signal()
-
 	// Close releases the resources associated with the pin.
 	Close() error
 }
@@ -116,13 +132,17 @@ type PWMPin interface {
 	Close() error
 }
 
+type GPIOInterrupt interface {
+	// Register a pin as an interrupt
+	RegisterInterrupt(p InterruptPin) error
+
+	// Unregister a pin as an interrupt
+	UnregisterInterrupt(p InterruptPin) error
+}
+
 // GPIODriver implements a generic GPIO driver.
 type GPIODriver interface {
-	// Register a pin as an interrupt pin
-	RegisterInterrupt(fd int, p DigitalPin) error
-
-	// Unregister the file handler from the Interrupt handler
-	UnregisterInterrupt(fd int) error
+	GPIOInterrupt
 
 	// Unregister unregisters the pin from the driver. Should be called when the pin is closed.
 	Unregister(string) error