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(std::shared_ptr<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(std::shared_ptr<ZoneInterface> zone,
50                     std::shared_ptr<boost::asio::steady_timer> timer,
51                     const bool* isCanceling, bool first, uint64_t cycleCnt)
52 {
53     if (*isCanceling)
54         return;
55 
56     if (first)
57     {
58         if (loggingEnabled)
59         {
60             zone->initializeLog();
61         }
62 
63         zone->initializeCache();
64         processThermals(zone);
65     }
66 
67     timer->expires_after(
68         std::chrono::milliseconds(zone->getCycleIntervalTime()));
69     timer->async_wait([zone, timer, cycleCnt, isCanceling](
70                           const boost::system::error_code& ec) mutable {
71         if (ec == boost::asio::error::operation_aborted)
72         {
73             return; // timer being canceled, stop loop
74         }
75 
76         /*
77          * This should sleep on the conditional wait for the listen thread
78          * to tell us it's in sync.  But then we also need a timeout option
79          * in case phosphor-hwmon is down, we can go into some weird failure
80          * more.
81          *
82          * Another approach would be to start all sensors in worst-case
83          * values, and fail-safe mode and then clear out of fail-safe mode
84          * once we start getting values.  Which I think it is a solid
85          * approach.
86          *
87          * For now this runs before it necessarily has any sensor values.
88          * For the host sensors they start out in fail-safe mode.  For the
89          * fans, they start out as 0 as input and then are adjusted once
90          * they have values.
91          *
92          * If a fan has failed, it's value will be whatever we're told or
93          * however we retrieve it.  This program disregards fan values of 0,
94          * so any code providing a fan speed can set to 0 on failure and
95          * that fan value will be effectively ignored.  The PID algorithm
96          * will be unhappy but nothing bad will happen.
97          *
98          * TODO(venture): If the fan value is 0 should that loop just be
99          * skipped? Right now, a 0 value is ignored in
100          * FanController::inputProc()
101          */
102 
103         // Check if we should just go back to sleep.
104         if (zone->getManualMode())
105         {
106             pidControlLoop(zone, timer, isCanceling, false, cycleCnt);
107             return;
108         }
109 
110         // Get the latest fan speeds.
111         zone->updateFanTelemetry();
112 
113         if (zone->getUpdateThermalsCycle() <= cycleCnt)
114         {
115             cycleCnt = 0;
116 
117             processThermals(zone);
118         }
119 
120         // Run the fan PIDs every iteration.
121         zone->processFans();
122 
123         if (loggingEnabled)
124         {
125             std::ostringstream out;
126             out << "," << zone->getFailSafeMode() << std::endl;
127             zone->writeLog(out.str());
128         }
129 
130         cycleCnt += 1;
131 
132         pidControlLoop(zone, timer, isCanceling, false, cycleCnt);
133     });
134 }
135 
136 } // namespace pid_control
137