1 /**
2  * Copyright 2017 Google Inc.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *     http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #include "pidloop.hpp"
18 
19 #include "pid/pidcontroller.hpp"
20 #include "pid/tuning.hpp"
21 #include "pid/zone_interface.hpp"
22 #include "sensors/sensor.hpp"
23 
24 #include <boost/asio/steady_timer.hpp>
25 
26 #include <chrono>
27 #include <map>
28 #include <memory>
29 #include <sstream>
30 #include <thread>
31 #include <vector>
32 
33 namespace pid_control
34 {
35 
36 static void processThermals(ZoneInterface* zone)
37 {
38     // Get the latest margins.
39     zone->updateSensors();
40     // Zero out the set point goals.
41     zone->clearSetPoints();
42     zone->clearRPMCeilings();
43     // Run the margin PIDs.
44     zone->processThermals();
45     // Get the maximum RPM setpoint.
46     zone->determineMaxSetPointRequest();
47 }
48 
49 void pidControlLoop(ZoneInterface* zone, boost::asio::steady_timer& timer,
50                     bool first, int ms100cnt)
51 {
52     if (first)
53     {
54         if (loggingEnabled)
55         {
56             zone->initializeLog();
57         }
58 
59         zone->initializeCache();
60         processThermals(zone);
61     }
62 
63     timer.expires_after(std::chrono::milliseconds(100));
64     timer.async_wait(
65         [zone, &timer, ms100cnt](const boost::system::error_code& ec) mutable {
66             if (ec == boost::asio::error::operation_aborted)
67             {
68                 return; // timer being canceled, stop loop
69             }
70 
71             /*
72              * This should sleep on the conditional wait for the listen thread
73              * to tell us it's in sync.  But then we also need a timeout option
74              * in case phosphor-hwmon is down, we can go into some weird failure
75              * more.
76              *
77              * Another approach would be to start all sensors in worst-case
78              * values, and fail-safe mode and then clear out of fail-safe mode
79              * once we start getting values.  Which I think it is a solid
80              * approach.
81              *
82              * For now this runs before it necessarily has any sensor values.
83              * For the host sensors they start out in fail-safe mode.  For the
84              * fans, they start out as 0 as input and then are adjusted once
85              * they have values.
86              *
87              * If a fan has failed, it's value will be whatever we're told or
88              * however we retrieve it.  This program disregards fan values of 0,
89              * so any code providing a fan speed can set to 0 on failure and
90              * that fan value will be effectively ignored.  The PID algorithm
91              * will be unhappy but nothing bad will happen.
92              *
93              * TODO(venture): If the fan value is 0 should that loop just be
94              * skipped? Right now, a 0 value is ignored in
95              * FanController::inputProc()
96              */
97 
98             // Check if we should just go back to sleep.
99             if (zone->getManualMode())
100             {
101                 pidControlLoop(zone, timer, false, ms100cnt);
102                 return;
103             }
104 
105             // Get the latest fan speeds.
106             zone->updateFanTelemetry();
107 
108             if (10 <= ms100cnt)
109             {
110                 ms100cnt = 0;
111 
112                 processThermals(zone);
113             }
114 
115             // Run the fan PIDs every iteration.
116             zone->processFans();
117 
118             if (loggingEnabled)
119             {
120                 std::ostringstream out;
121                 out << "," << zone->getFailSafeMode() << std::endl;
122                 zone->writeLog(out.str());
123             }
124 
125             ms100cnt += 1;
126 
127             pidControlLoop(zone, timer, false, ms100cnt);
128         });
129 }
130 
131 } // namespace pid_control
132