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                     bool first, int ms100cnt)
52 {
53     if (first)
54     {
55         if (loggingEnabled)
56         {
57             zone->initializeLog();
58         }
59 
60         zone->initializeCache();
61         processThermals(zone);
62     }
63 
64     timer->expires_after(std::chrono::milliseconds(100));
65     timer->async_wait(
66         [zone, timer, ms100cnt](const boost::system::error_code& ec) mutable {
67             if (ec == boost::asio::error::operation_aborted)
68             {
69                 return; // timer being canceled, stop loop
70             }
71 
72             /*
73              * This should sleep on the conditional wait for the listen thread
74              * to tell us it's in sync.  But then we also need a timeout option
75              * in case phosphor-hwmon is down, we can go into some weird failure
76              * more.
77              *
78              * Another approach would be to start all sensors in worst-case
79              * values, and fail-safe mode and then clear out of fail-safe mode
80              * once we start getting values.  Which I think it is a solid
81              * approach.
82              *
83              * For now this runs before it necessarily has any sensor values.
84              * For the host sensors they start out in fail-safe mode.  For the
85              * fans, they start out as 0 as input and then are adjusted once
86              * they have values.
87              *
88              * If a fan has failed, it's value will be whatever we're told or
89              * however we retrieve it.  This program disregards fan values of 0,
90              * so any code providing a fan speed can set to 0 on failure and
91              * that fan value will be effectively ignored.  The PID algorithm
92              * will be unhappy but nothing bad will happen.
93              *
94              * TODO(venture): If the fan value is 0 should that loop just be
95              * skipped? Right now, a 0 value is ignored in
96              * FanController::inputProc()
97              */
98 
99             // Check if we should just go back to sleep.
100             if (zone->getManualMode())
101             {
102                 pidControlLoop(zone, timer, false, ms100cnt);
103                 return;
104             }
105 
106             // Get the latest fan speeds.
107             zone->updateFanTelemetry();
108 
109             if (10 <= ms100cnt)
110             {
111                 ms100cnt = 0;
112 
113                 processThermals(zone);
114             }
115 
116             // Run the fan PIDs every iteration.
117             zone->processFans();
118 
119             if (loggingEnabled)
120             {
121                 std::ostringstream out;
122                 out << "," << zone->getFailSafeMode() << std::endl;
123                 zone->writeLog(out.str());
124             }
125 
126             ms100cnt += 1;
127 
128             pidControlLoop(zone, timer, false, ms100cnt);
129         });
130 }
131 
132 } // namespace pid_control
133