1 /*
2 * Copyright 2016 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include "ThermalManager.h"
9
10 #include "SkOSFile.h"
11
12 #include <stdio.h>
13
14 #ifndef SK_BUILD_FOR_WIN32
15 #include <unistd.h>
16 #endif
17
18 #ifdef THERMAL_MANAGER_SUPPORTED
19
20 /*
21 * ThermalManager is completely dependent on sysfs to monitor thermal temperatures. In sysfs
22 * thermal management is controlled by a number of thermal zones. They are laid out as follows:
23 * /sys/class/thermal/thermal_zoneN where N is the number of the thermal zone starting at 0.
24 *
25 * Inside each thermal_zone folder is a file called 'temp,' which has the current temperature
26 * reading from the sensor in that zone, as well as 0 or more files called 'trip_point_N_temp.'
27 *
28 * When the reading in temp is greater than one of the numbers in the trip_point files, then the
29 * kernel will take some kind of action. This is all documented online.
30 *
31 * In any case, the goal of this class is to sleep right before a trip point is about to be
32 * triggered, thus naturally cooling the system and preventing thermal throttling.
33 */
34
ThermalManager(int32_t threshold,uint32_t sleepIntervalMs,uint32_t timeoutMs)35 ThermalManager::ThermalManager(int32_t threshold, uint32_t sleepIntervalMs, uint32_t timeoutMs)
36 : fSleepIntervalMs(sleepIntervalMs)
37 , fTimeoutMs(timeoutMs) {
38 static const char* kThermalZonePath = "/sys/class/thermal/";
39 SkOSFile::Iter it(kThermalZonePath);
40 SkString path;
41 while (it.next(&path, true)) {
42 if (!path.contains("thermal_zone")) {
43 continue;
44 }
45
46 SkString fullPath(kThermalZonePath);
47 fullPath.append(path);
48 SkOSFile::Iter thermalZoneIt(fullPath.c_str());
49
50 SkString filename;
51 while (thermalZoneIt.next(&filename)) {
52 if (!(filename.contains("trip_point") && filename.contains("temp"))) {
53 continue;
54 }
55
56 fTripPoints.push_back(TripPoint(fullPath, filename, threshold));
57 }
58 }
59 }
60
coolOffIfNecessary()61 bool ThermalManager::coolOffIfNecessary() {
62 uint32_t i = 0, totalTimeSleptMs = 0;
63 while (i < (uint32_t)fTripPoints.count() && totalTimeSleptMs < fTimeoutMs) {
64 if (fTripPoints[i].willTrip()) {
65 sleep(fSleepIntervalMs);
66 totalTimeSleptMs += fSleepIntervalMs;
67 } else {
68 i++;
69 }
70 }
71
72 return totalTimeSleptMs < fTimeoutMs;
73 }
74
OpenFileAndReadInt32(const char * path)75 int32_t ThermalManager::OpenFileAndReadInt32(const char* path) {
76 FILE* tempFile = fopen(path, "r");
77 SkASSERT(tempFile);
78 int32_t value;
79 int ret = fscanf(tempFile, "%d", &value);
80 if (!ret) {
81 SkDebugf("Could not read temperature\n");
82 SkASSERT(false);
83 }
84
85 fclose(tempFile);
86 return value;
87 }
88
TripPoint(SkString thermalZoneRoot,SkString pointName,int32_t threshold)89 ThermalManager::TripPoint::TripPoint(SkString thermalZoneRoot, SkString pointName,
90 int32_t threshold)
91 : fThermalZoneRoot(thermalZoneRoot)
92 , fPointName(pointName) {
93 SkString fullPath(thermalZoneRoot);
94 fullPath.appendf("/%s", pointName.c_str());
95 fPoint = OpenFileAndReadInt32(fullPath.c_str());
96 fBase = GetTemp(fThermalZoneRoot);
97 fThreshold = threshold;
98 fDisabled = fBase + fThreshold >= fPoint; // We disable any trip point which start off
99 // triggered
100 }
101
willTrip()102 bool ThermalManager::TripPoint::willTrip() {
103 int32_t currentTemp = GetTemp(fThermalZoneRoot);
104 bool wouldTrip = !fDisabled && currentTemp + fThreshold >= fPoint;
105
106 if (wouldTrip) {
107 SkDebugf("%s/%s would trip {%d,%d,%d,%d}\n", fThermalZoneRoot.c_str(),
108 fPointName.c_str(), fBase, currentTemp, fPoint, fThreshold);
109 }
110 return wouldTrip;
111 }
112
113 #endif
114