#!/usr/bin/env python
#
# Control the fan according to temperature and load
#
# Copyright (c) 2012, Matthias P. Braendli <matthias@mpb.li>
# 
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
# AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
# OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
# PERFORMANCE OF THIS SOFTWARE.

import time
import os
import daemon
import lockfile
import signal

# I'll count SMT as cores
NUM_PROC = 4

# graph_points define the function mapping temperature to fanspeed
# linear interpolation inbetween, flat outside
graph_points = {39: 0, 40: 80, 50: 160, 60: 255} 

# load increase factor defines by what factor*norm_load we must increase 
# the temperature (calc_temp = real_temp + load_increase_factor * norm_load)
load_increase_factor_day = 8
load_increase_factor_night = 0

# stronger ventilation during those hours
day = [9, 22]


PWM_ENABLE_FILE = "/sys/devices/platform/w83627ehf.656/hwmon/hwmon1/device/pwm2_enable"
FAN_PWM =         "/sys/devices/platform/w83627ehf.656/hwmon/hwmon1/device/pwm2"

CORETEMP_FOLDER = "/sys/devices/platform/coretemp.0"


def enable_pwm():
    """Initial setup"""
    with open(PWM_ENABLE_FILE, 'w') as fd:
        fd.write('1')

def load_increase_factor():
    """According to time of day, return load increase factor"""
    now = time.gmtime().tm_hour
    if day[0] <= now < day[1]:
        return load_increase_factor_day
    else:
        return load_increase_factor_night

def get_normalised_load():
    """Return the load average in the last minute divided by the number of processors"""
    return os.getloadavg()[0] / NUM_PROC


def get_temperature():
    """Return the maximum of the two CPU temperatures"""
    core0_temp_file = CORETEMP_FOLDER + "/temp1_input"
    core1_temp_file = CORETEMP_FOLDER + "/temp2_input"
    
    with open(core0_temp_file) as fd:
        temp0 = fd.read()

    with open(core1_temp_file) as fd:
        temp1 = fd.read()

    return max([int(t) / 1000 for t in [temp0, temp1]])


def set_fan(speed):
    """Set the fanspeed. speed is between 0 and 255"""
    print("Setting fan to {0}...".format(speed))
    with open(FAN_PWM, "w") as fd:
        fd.write(str(speed))
        print("Fanspeed set.")


def calculate_fan_speed():
    """Calculate desired fanspeed according to system state"""
    temp_incr = load_increase_factor() * get_normalised_load()
    temp_real = get_temperature()
    temp = int(temp_real + temp_incr)
    print("real / load compensated temperature: {0} / {1}".format(temp_real, temp))

    # interpolate fanspeed

    temp_points = sorted(graph_points.keys())

    last_tp = temp_points[0]
    if temp < last_tp:
        return graph_points[last_tp]
    for tp in temp_points:
        if temp == tp:
            return graph_points[tp]
        elif temp < tp:
            f1 = graph_points[tp]
            f2 = graph_points[last_tp]
            fraction = 1.0 * (temp - last_tp) / (tp - last_tp)
            return int(fraction * f1 + (1-fraction) * f2)
        last_tp = tp
    return graph_points[tp]

running = True

def quit():
    running = False

def main():
    enable_pwm()
    while running:
        try:
            fanspeed = calculate_fan_speed()
            #print("New fan speed {0}".format(fanspeed))
            set_fan(fanspeed)
        except KeyboardInterrupt:
            break
        #except:
         #   print("Exception occurred")
        time.sleep(20)

context = daemon.DaemonContext(pidfile=lockfile.FileLock('/var/run/ventilator.pid'))

context.signal_map = {
    signal.SIGTERM: quit,
    }

print("Testing")
enable_pwm()

fanspeed = calculate_fan_speed()
print("Fan speed {0}".format(fanspeed))
set_fan(fanspeed)

print("starting daemon")
with context:
    main()