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 
25 #include <chrono>
26 #include <map>
27 #include <memory>
28 #include <thread>
29 #include <vector>
30 
31 namespace pid_control
32 {
33 
34 static void processThermals(DbusPidZone* zone)
35 {
36     // Get the latest margins.
37     zone->updateSensors();
38     // Zero out the set point goals.
39     zone->clearSetPoints();
40     zone->clearRPMCeilings();
41     // Run the margin PIDs.
42     zone->processThermals();
43     // Get the maximum RPM setpoint.
44     zone->determineMaxSetPointRequest();
45 }
46 
47 void pidControlLoop(DbusPidZone* zone, boost::asio::steady_timer& timer,
48                     bool first, int ms100cnt)
49 {
50     if (first)
51     {
52         if (loggingEnabled)
53         {
54             zone->initializeLog();
55         }
56 
57         zone->initializeCache();
58         processThermals(zone);
59     }
60 
61     timer.expires_after(std::chrono::milliseconds(100));
62     timer.async_wait(
63         [zone, &timer, ms100cnt](const boost::system::error_code& ec) mutable {
64             if (ec == boost::asio::error::operation_aborted)
65             {
66                 return; // timer being canceled, stop loop
67             }
68 
69             /*
70              * This should sleep on the conditional wait for the listen thread
71              * to tell us it's in sync.  But then we also need a timeout option
72              * in case phosphor-hwmon is down, we can go into some weird failure
73              * more.
74              *
75              * Another approach would be to start all sensors in worst-case
76              * values, and fail-safe mode and then clear out of fail-safe mode
77              * once we start getting values.  Which I think it is a solid
78              * approach.
79              *
80              * For now this runs before it necessarily has any sensor values.
81              * For the host sensors they start out in fail-safe mode.  For the
82              * fans, they start out as 0 as input and then are adjusted once
83              * they have values.
84              *
85              * If a fan has failed, it's value will be whatever we're told or
86              * however we retrieve it.  This program disregards fan values of 0,
87              * so any code providing a fan speed can set to 0 on failure and
88              * that fan value will be effectively ignored.  The PID algorithm
89              * will be unhappy but nothing bad will happen.
90              *
91              * TODO(venture): If the fan value is 0 should that loop just be
92              * skipped? Right now, a 0 value is ignored in
93              * FanController::inputProc()
94              */
95 
96             // Check if we should just go back to sleep.
97             if (zone->getManualMode())
98             {
99                 pidControlLoop(zone, timer, false, ms100cnt);
100                 return;
101             }
102 
103             // Get the latest fan speeds.
104             zone->updateFanTelemetry();
105 
106             if (10 <= ms100cnt)
107             {
108                 ms100cnt = 0;
109 
110                 processThermals(zone);
111             }
112 
113             // Run the fan PIDs every iteration.
114             zone->processFans();
115 
116             if (loggingEnabled)
117             {
118                 zone->getLogHandle() << "," << zone->getFailSafeMode();
119                 zone->getLogHandle() << std::endl;
120             }
121 
122             ms100cnt += 1;
123 
124             pidControlLoop(zone, timer, false, ms100cnt);
125         });
126 }
127 
128 } // namespace pid_control
129