sysfs: define DigitalPinnerProvider and PWMPinnerProvider interfaces

Signed-off-by: deadprogram <ron@hybridgroup.com>

sysfs/digital_pin.go

@@ -38,6 +38,12 @@ type DigitalPinner interface {
 	Write(int) error
 }
 
+// DigitalPinnerProvider is the interface that an Adaptor should implement to allow
+// clients to obtain access to any DigitalPin's available on that board.
+type DigitalPinnerProvider interface {
+	DigitalPin(string, string) (DigitalPinner, error)
+}
+
 type DigitalPin struct {
 	pin   string
 	label string

sysfs/pwm_pin.go

@@ -28,6 +28,12 @@ type PWMPinner interface {
 	SetDutyCycle(duty uint32) (err error)
 }
 
+// PWMPinnerProvider is the interface that an Adaptor should implement to allow
+// clients to obtain access to any PWMPin's available on that board.
+type PWMPinnerProvider interface {
+	PWMPin(string) (PWMPinner, error)
+}
+
 type PWMPin struct {
 	pin     string
 	Chip    string