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 "sensors/sensor.hpp"
22 
23 #include <boost/asio/steady_timer.hpp>
24 #include <chrono>
25 #include <map>
26 #include <memory>
27 #include <thread>
28 #include <vector>
29 
30 static void processThermals(PIDZone* zone)
31 {
32     // Get the latest margins.
33     zone->updateSensors();
34     // Zero out the RPM set point goals.
35     zone->clearRPMSetPoints();
36     zone->clearRPMCeilings();
37     // Run the margin PIDs.
38     zone->processThermals();
39     // Get the maximum RPM setpoint.
40     zone->determineMaxRPMRequest();
41 }
42 
43 void pidControlLoop(PIDZone* zone, boost::asio::steady_timer& timer, bool first,
44                     int ms100cnt)
45 {
46     if (first)
47     {
48         if (loggingEnabled)
49         {
50             zone->initializeLog();
51         }
52 
53         zone->initializeCache();
54         processThermals(zone);
55     }
56 
57     timer.expires_after(std::chrono::milliseconds(100));
58     timer.async_wait(
59         [zone, &timer, ms100cnt](const boost::system::error_code& ec) mutable {
60             if (ec == boost::asio::error::operation_aborted)
61             {
62                 return; // timer being canceled, stop loop
63             }
64 
65             /*
66              * This should sleep on the conditional wait for the listen thread
67              * to tell us it's in sync.  But then we also need a timeout option
68              * in case phosphor-hwmon is down, we can go into some weird failure
69              * more.
70              *
71              * Another approach would be to start all sensors in worst-case
72              * values, and fail-safe mode and then clear out of fail-safe mode
73              * once we start getting values.  Which I think it is a solid
74              * approach.
75              *
76              * For now this runs before it necessarily has any sensor values.
77              * For the host sensors they start out in fail-safe mode.  For the
78              * fans, they start out as 0 as input and then are adjusted once
79              * they have values.
80              *
81              * If a fan has failed, it's value will be whatever we're told or
82              * however we retrieve it.  This program disregards fan values of 0,
83              * so any code providing a fan speed can set to 0 on failure and
84              * that fan value will be effectively ignored.  The PID algorithm
85              * will be unhappy but nothing bad will happen.
86              *
87              * TODO(venture): If the fan value is 0 should that loop just be
88              * skipped? Right now, a 0 value is ignored in
89              * FanController::inputProc()
90              */
91 
92             // Check if we should just go back to sleep.
93             if (zone->getManualMode())
94             {
95                 pidControlLoop(zone, timer, false, ms100cnt);
96                 return;
97             }
98 
99             // Get the latest fan speeds.
100             zone->updateFanTelemetry();
101 
102             if (10 <= ms100cnt)
103             {
104                 ms100cnt = 0;
105 
106                 processThermals(zone);
107             }
108 
109             // Run the fan PIDs every iteration.
110             zone->processFans();
111 
112             if (loggingEnabled)
113             {
114                 zone->getLogHandle() << "," << zone->getFailSafeMode();
115                 zone->getLogHandle() << std::endl;
116             }
117 
118             ms100cnt += 1;
119 
120             pidControlLoop(zone, timer, false, ms100cnt);
121         });
122 }
123