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
35ThermalManager::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
61bool 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
75int32_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
89ThermalManager::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    if (!fDisabled) {
101        SkDebugf("Trip point %s base - %d trip point-%d\n", fullPath.c_str(),
102                 fBase, fPoint);
103    }
104}
105
106bool ThermalManager::TripPoint::willTrip() {
107    int32_t currentTemp = GetTemp(fThermalZoneRoot);
108    bool wouldTrip = !fDisabled && currentTemp + fThreshold >= fPoint;
109
110    if (wouldTrip) {
111        SkDebugf("%s/%s would trip {%d,%d,%d,%d}\n", fThermalZoneRoot.c_str(),
112                 fPointName.c_str(), fBase, currentTemp, fPoint, fThreshold);
113    }
114    return wouldTrip;
115}
116
117#endif
118