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 <vector>
31
32 namespace pid_control
33 {
34
processThermals(std::shared_ptr<ZoneInterface> zone)35 static void processThermals(std::shared_ptr<ZoneInterface> zone)
36 {
37 // Get the latest margins.
38 zone->updateSensors();
39 // Zero out the set point goals.
40 zone->clearSetPoints();
41 zone->clearRPMCeilings();
42 // Run the margin PIDs.
43 zone->processThermals();
44 // Get the maximum RPM setpoint.
45 zone->determineMaxSetPointRequest();
46 }
47
pidControlLoop(std::shared_ptr<ZoneInterface> zone,std::shared_ptr<boost::asio::steady_timer> timer,const bool * isCanceling,bool first,uint64_t cycleCnt)48 void pidControlLoop(std::shared_ptr<ZoneInterface> zone,
49 std::shared_ptr<boost::asio::steady_timer> timer,
50 const bool* isCanceling, bool first, uint64_t cycleCnt)
51 {
52 if (*isCanceling)
53 return;
54
55 std::chrono::steady_clock::time_point nextTime;
56
57 if (first)
58 {
59 if (loggingEnabled)
60 {
61 zone->initializeLog();
62 }
63
64 zone->initializeCache();
65 processThermals(zone);
66
67 nextTime = std::chrono::steady_clock::now();
68 }
69 else
70 {
71 nextTime = timer->expiry();
72 }
73
74 uint64_t msPerFanCycle = zone->getCycleIntervalTime();
75
76 // Push forward the original expiration time of timer, instead of just
77 // resetting it with expires_after() from now, to make sure the interval
78 // is of the expected duration, and not stretched out by CPU time taken.
79 nextTime += std::chrono::milliseconds(msPerFanCycle);
80 timer->expires_at(nextTime);
81 timer->async_wait([zone, timer, cycleCnt, isCanceling, msPerFanCycle](
82 const boost::system::error_code& ec) mutable {
83 if (ec == boost::asio::error::operation_aborted)
84 {
85 return; // timer being canceled, stop loop
86 }
87
88 /*
89 * This should sleep on the conditional wait for the listen thread
90 * to tell us it's in sync. But then we also need a timeout option
91 * in case phosphor-hwmon is down, we can go into some weird failure
92 * more.
93 *
94 * Another approach would be to start all sensors in worst-case
95 * values, and fail-safe mode and then clear out of fail-safe mode
96 * once we start getting values. Which I think it is a solid
97 * approach.
98 *
99 * For now this runs before it necessarily has any sensor values.
100 * For the host sensors they start out in fail-safe mode. For the
101 * fans, they start out as 0 as input and then are adjusted once
102 * they have values.
103 *
104 * If a fan has failed, it's value will be whatever we're told or
105 * however we retrieve it. This program disregards fan values of 0,
106 * so any code providing a fan speed can set to 0 on failure and
107 * that fan value will be effectively ignored. The PID algorithm
108 * will be unhappy but nothing bad will happen.
109 *
110 * TODO(venture): If the fan value is 0 should that loop just be
111 * skipped? Right now, a 0 value is ignored in
112 * FanController::inputProc()
113 */
114
115 // Check if we should just go back to sleep.
116 if (zone->getManualMode())
117 {
118 pidControlLoop(zone, timer, isCanceling, false, cycleCnt);
119 return;
120 }
121
122 // Get the latest fan speeds.
123 zone->updateFanTelemetry();
124
125 uint64_t msPerThermalCycle = zone->getUpdateThermalsCycle();
126
127 // Process thermal cycles at a rate that is less often than fan
128 // cycles. If thermal time is not an exact multiple of fan time,
129 // there will be some remainder left over, to keep the timing
130 // correct, as the intervals are staggered into one another.
131 if (cycleCnt >= msPerThermalCycle)
132 {
133 cycleCnt -= msPerThermalCycle;
134
135 processThermals(zone);
136 }
137
138 // Run the fan PIDs every iteration.
139 zone->processFans();
140
141 if (loggingEnabled)
142 {
143 std::ostringstream out;
144 out << "," << zone->getFailSafeMode() << std::endl;
145 zone->writeLog(out.str());
146 }
147
148 // Count how many milliseconds have elapsed, so we can know when
149 // to perform thermal cycles, in proper ratio with fan cycles.
150 cycleCnt += msPerFanCycle;
151
152 pidControlLoop(zone, timer, isCanceling, false, cycleCnt);
153 });
154 }
155
156 } // namespace pid_control
157