def METHOD_NAME(self):
    """
    Retrieves the speed of fan as a percentage of full speed
    Returns:
        An integer, the percentage of full fan speed, in the range 0 (off)
             to 100 (full speed)
    """
    speed = 0
    if self.is_psu_fan:
        psu_fan_path= "{}{}".format(self.psu_hwmon_path, 'psu_fan1_speed_rpm')
        fan_speed_rpm = self._api_helper.read_txt_file(psu_fan_path)
        if fan_speed_rpm is not None:
            speed = (int(fan_speed_rpm,10))*100/26688
            if speed > 100:
                speed=100
        else:
            return 0
    elif self.get_presence():            
        speed_path = "{}{}".format(CPLD_I2C_PATH, '_duty_cycle_percentage')
        speed=self._api_helper.read_txt_file(speed_path)
        if speed is None:
            return 0
    return int(speed)