Add a LED in chassis (#18)

LED was equipped in the chassis. This patch turns it on.
SlowLED changes the brightness gradually. wiringpi is used for it to leverage the hardware PWA equipped by Raspberry Pi.

mozc-nazoru/src/nazoru/led.py

@@ -16,7 +16,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-class LEDBase():
+class LEDBase(object):
   def __init__(self, pin):
     self._pin = pin
   def on(self):
@@ -25,17 +25,19 @@ class LEDBase():
     pass
   def blink(self, interval):
     pass
+  def set_brightness(self, brightness):
+    pass
 
 try:
   import RPi.GPIO as GPIO
   import threading
+  GPIO.setmode(GPIO.BOARD)
 
   class LED(LEDBase):
     ON = 'ON'
     OFF = 'OFF'
 
     def __init__(self, pin):
-      GPIO.setmode(GPIO.BOARD)
       self._pin = pin
       self._lock = threading.Lock()
       self._timer = None
@@ -72,11 +74,72 @@ try:
         self._timer.cancel()
         self._timer = None
 
+  import wiringpi
+  wiringpi.wiringPiSetupPhys()
+  class SlowLED(LEDBase):
+    DUTY_MAX = 1024
+    INTERVAL_MS = 10
+
+    def __init__(self, pin, delay_ms):
+      self._pin = pin
+      self._delay_ms = delay_ms
+      wiringpi.pinMode(pin, wiringpi.GPIO.PWM_OUTPUT)
+      self._target_duty = 0
+      self._current_duty = 0
+      self._remaining_cycles = 0
+      self._lock = threading.Lock()
+      self._timer = None
+      self.off()
+
+    # Called every 10ms
+    def _update(self):
+      with self._lock:
+        diff = (self._target_duty - self._current_duty) // \
+               self._remaining_cycles
+        self._current_duty += diff
+        self._remaining_cycles -= 1
+        self._set_duty_immediate(self._current_duty)
+        if self._remaining_cycles == 0:
+          self._timer.cancel()
+          self._timer = None
+          return
+        self._timer = threading.Timer(self.INTERVAL_MS * 0.001, self._update)
+        self._timer.daemon = True
+        self._timer.start()
+
+
+    # |duty|: 0 - 100
+    def _set_duty_immediate(self, duty):
+      wiringpi.pwmWrite(self._pin, int(self.DUTY_MAX * duty // 100))
+
+    def _set_duty_slow(self, duty, time_ms):
+      with self._lock:
+        self._target_duty = duty
+        self._remaining_cycles = time_ms // self.INTERVAL_MS
+        if self._timer is None:
+          self._timer = threading.Timer(self.INTERVAL_MS * 0.001, self._update)
+          self._timer.daemon = True
+          self._timer.start()
+
+    def on(self):
+      self._set_duty_slow(100, self._delay_ms)
+
+    def off(self):
+      self._set_duty_slow(0, self._delay_ms)
+
+    # |brightness|: 0 - 100
+    def set_brightness(self, brightness):
+      self._set_duty_slow(brightness, self._delay_ms)
+
 except ImportError as e:
   import sys
 
   class LED(LEDBase):
     pass
+  class SlowLED(LEDBase):
+    def __init__(self, pin, delay_ms):
+      super(SlowLED, self).__init__(pin)
 
 LED_BLUE = LED(38)
 LED_RED = LED(40)
+LED_CHASSIS = SlowLED(32, 500)