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, int ms100cnt)
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(std::chrono::milliseconds(100));
68     timer->async_wait([zone, timer, ms100cnt, isCanceling](
69                           const boost::system::error_code& ec) mutable {
70         if (ec == boost::asio::error::operation_aborted)
71         {
72             return; // timer being canceled, stop loop
73         }
74 
75         /*
76          * This should sleep on the conditional wait for the listen thread
77          * to tell us it's in sync.  But then we also need a timeout option
78          * in case phosphor-hwmon is down, we can go into some weird failure
79          * more.
80          *
81          * Another approach would be to start all sensors in worst-case
82          * values, and fail-safe mode and then clear out of fail-safe mode
83          * once we start getting values.  Which I think it is a solid
84          * approach.
85          *
86          * For now this runs before it necessarily has any sensor values.
87          * For the host sensors they start out in fail-safe mode.  For the
88          * fans, they start out as 0 as input and then are adjusted once
89          * they have values.
90          *
91          * If a fan has failed, it's value will be whatever we're told or
92          * however we retrieve it.  This program disregards fan values of 0,
93          * so any code providing a fan speed can set to 0 on failure and
94          * that fan value will be effectively ignored.  The PID algorithm
95          * will be unhappy but nothing bad will happen.
96          *
97          * TODO(venture): If the fan value is 0 should that loop just be
98          * skipped? Right now, a 0 value is ignored in
99          * FanController::inputProc()
100          */
101 
102         // Check if we should just go back to sleep.
103         if (zone->getManualMode())
104         {
105             pidControlLoop(zone, timer, isCanceling, false, ms100cnt);
106             return;
107         }
108 
109         // Get the latest fan speeds.
110         zone->updateFanTelemetry();
111 
112         if (10 <= ms100cnt)
113         {
114             ms100cnt = 0;
115 
116             processThermals(zone);
117         }
118 
119         // Run the fan PIDs every iteration.
120         zone->processFans();
121 
122         if (loggingEnabled)
123         {
124             std::ostringstream out;
125             out << "," << zone->getFailSafeMode() << std::endl;
126             zone->writeLog(out.str());
127         }
128 
129         ms100cnt += 1;
130 
131         pidControlLoop(zone, timer, isCanceling, false, ms100cnt);
132     });
133 }
134 
135 } // namespace pid_control
136