1 /* 2 * Copyright (C) 2020 The Android Open Source Project 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 /** 18 * @addtogroup Thermal 19 * @{ 20 */ 21 22 /** 23 * @file thermal.h 24 */ 25 26 #ifndef _ANDROID_THERMAL_H 27 #define _ANDROID_THERMAL_H 28 29 #include <sys/cdefs.h> 30 31 /****************************************************************** 32 * 33 * IMPORTANT NOTICE: 34 * 35 * This file is part of Android's set of stable system headers 36 * exposed by the Android NDK (Native Development Kit). 37 * 38 * Third-party source AND binary code relies on the definitions 39 * here to be FROZEN ON ALL UPCOMING PLATFORM RELEASES. 40 * 41 * - DO NOT MODIFY ENUMS (EXCEPT IF YOU ADD NEW 32-BIT VALUES) 42 * - DO NOT MODIFY CONSTANTS OR FUNCTIONAL MACROS 43 * - DO NOT CHANGE THE SIGNATURE OF FUNCTIONS IN ANY WAY 44 * - DO NOT CHANGE THE LAYOUT OR SIZE OF STRUCTURES 45 */ 46 47 /* 48 * Structures and functions to access thermal status and register/unregister 49 * thermal status listener in native code. 50 */ 51 52 #include <stdint.h> 53 #include <sys/types.h> 54 55 #if !defined(__INTRODUCED_IN) 56 #define __INTRODUCED_IN(__api_level) /* nothing */ 57 #endif 58 59 #ifdef __cplusplus 60 extern "C" { 61 #endif 62 63 /** 64 * Thermal status used in function {@link AThermal_getCurrentThermalStatus} and 65 * {@link AThermal_StatusCallback}. 66 */ 67 enum AThermalStatus { 68 /** Error in thermal status. */ 69 ATHERMAL_STATUS_ERROR = -1, 70 /** Not under throttling. */ 71 ATHERMAL_STATUS_NONE = 0, 72 /** Light throttling where UX is not impacted. */ 73 ATHERMAL_STATUS_LIGHT = 1, 74 /** Moderate throttling where UX is not largely impacted. */ 75 ATHERMAL_STATUS_MODERATE = 2, 76 /** Severe throttling where UX is largely impacted. */ 77 ATHERMAL_STATUS_SEVERE = 3, 78 /** Platform has done everything to reduce power. */ 79 ATHERMAL_STATUS_CRITICAL = 4, 80 /** 81 * Key components in platform are shutting down due to thermal condition. 82 * Device functionalities will be limited. 83 */ 84 ATHERMAL_STATUS_EMERGENCY = 5, 85 /** Need shutdown immediately. */ 86 ATHERMAL_STATUS_SHUTDOWN = 6, 87 }; 88 89 /** 90 * An opaque type representing a handle to a thermal manager. 91 * An instance of thermal manager must be acquired prior to 92 * using thermal status APIs and must be released after use. 93 * 94 * <p>To use:<ul> 95 * <li>Create a new thermal manager instance by calling the 96 * {@link AThermal_acquireManager} function.</li> 97 * <li>Get current thermal status with 98 * {@link AThermal_getCurrentThermalStatus}.</li> 99 * <li>Register a thermal status listener with 100 * {@link AThermal_registerThermalStatusListener}.</li> 101 * <li>Unregister a thermal status listener with 102 * {@link AThermal_unregisterThermalStatusListener}.</li> 103 * <li>Release the thermal manager instance with 104 * {@link AThermal_releaseManager}.</li></ul></p> 105 * 106 */ 107 typedef struct AThermalManager AThermalManager; 108 109 /** 110 * Prototype of the function that is called when thermal status changes. 111 * It's passed the updated thermal status as parameter, as well as the 112 * pointer provided by the client that registered a callback. 113 */ 114 typedef void (*AThermal_StatusCallback)(void* _Nullable data, AThermalStatus status); 115 116 /** 117 * Acquire an instance of the thermal manager. This must be freed using 118 * {@link AThermal_releaseManager}. 119 * 120 * Available since API level 30. 121 * 122 * @return manager instance on success, nullptr on failure. 123 */ 124 AThermalManager* _Nonnull AThermal_acquireManager() __INTRODUCED_IN(30); 125 126 /** 127 * Release the thermal manager pointer acquired via 128 * {@link AThermal_acquireManager}. 129 * 130 * Available since API level 30. 131 * 132 * @param manager The manager to be released. 133 */ 134 void AThermal_releaseManager(AThermalManager* _Nonnull manager) __INTRODUCED_IN(30); 135 136 /** 137 * Gets the current thermal status. 138 * 139 * Available since API level 30. 140 * 141 * @param manager The manager instance to use to query the thermal status. 142 * Acquired via {@link AThermal_acquireManager}. 143 * 144 * @return current thermal status, ATHERMAL_STATUS_ERROR on failure. 145 */ 146 AThermalStatus 147 AThermal_getCurrentThermalStatus(AThermalManager* _Nonnull manager) __INTRODUCED_IN(30); 148 149 /** 150 * Register the thermal status listener for thermal status change. 151 * 152 * Available since API level 30. 153 * 154 * @param manager The manager instance to use to register. 155 * Acquired via {@link AThermal_acquireManager}. 156 * @param callback The callback function to be called when thermal status updated. 157 * @param data The data pointer to be passed when callback is called. 158 * 159 * @return 0 on success 160 * EINVAL if the listener and data pointer were previously added and not removed. 161 * EPERM if the required permission is not held. 162 * EPIPE if communication with the system service has failed. 163 */ 164 int AThermal_registerThermalStatusListener(AThermalManager* _Nonnull manager, 165 AThermal_StatusCallback _Nullable callback, 166 void* _Nullable data) __INTRODUCED_IN(30); 167 168 /** 169 * Unregister the thermal status listener previously resgistered. 170 * 171 * Available since API level 30. 172 * 173 * @param manager The manager instance to use to unregister. 174 * Acquired via {@link AThermal_acquireManager}. 175 * @param callback The callback function to be called when thermal status updated. 176 * @param data The data pointer to be passed when callback is called. 177 * 178 * @return 0 on success 179 * EINVAL if the listener and data pointer were not previously added. 180 * EPERM if the required permission is not held. 181 * EPIPE if communication with the system service has failed. 182 */ 183 int AThermal_unregisterThermalStatusListener(AThermalManager* _Nonnull manager, 184 AThermal_StatusCallback _Nullable callback, 185 void* _Nullable data) __INTRODUCED_IN(30); 186 187 /** 188 * Provides an estimate of how much thermal headroom the device currently has before 189 * hitting severe throttling. 190 * 191 * Note that this only attempts to track the headroom of slow-moving sensors, such as 192 * the skin temperature sensor. This means that there is no benefit to calling this function 193 * more frequently than about once per second, and attempted to call significantly 194 * more frequently may result in the function returning `NaN`. 195 * 196 * In addition, in order to be able to provide an accurate forecast, the system does 197 * not attempt to forecast until it has multiple temperature samples from which to 198 * extrapolate. This should only take a few seconds from the time of the first call, 199 * but during this time, no forecasting will occur, and the current headroom will be 200 * returned regardless of the value of `forecastSeconds`. 201 * 202 * The value returned is a non-negative float that represents how much of the thermal envelope 203 * is in use (or is forecasted to be in use). A value of 1.0 indicates that the device is 204 * (or will be) throttled at {@link #ATHERMAL_STATUS_SEVERE}. Such throttling can affect the 205 * CPU, GPU, and other subsystems. Values may exceed 1.0, but there is no implied mapping 206 * to specific thermal levels beyond that point. This means that values greater than 1.0 207 * may correspond to {@link #ATHERMAL_STATUS_SEVERE}, but may also represent heavier throttling. 208 * 209 * A value of 0.0 corresponds to a fixed distance from 1.0, but does not correspond to any 210 * particular thermal status or temperature. Values on (0.0, 1.0] may be expected to scale 211 * linearly with temperature, though temperature changes over time are typically not linear. 212 * Negative values will be clamped to 0.0 before returning. 213 * 214 * Available since API level 31. 215 * 216 * @param manager The manager instance to use. 217 * Acquired via {@link AThermal_acquireManager}. 218 * @param forecastSeconds how many seconds into the future to forecast. Given that device 219 * conditions may change at any time, forecasts from further in the 220 * future will likely be less accurate than forecasts in the near future. 221 * @return a value greater than equal to 0.0, where 1.0 indicates the SEVERE throttling threshold, 222 * as described above. Returns NaN if the device does not support this functionality or 223 * if this function is called significantly faster than once per second. 224 */ 225 float AThermal_getThermalHeadroom(AThermalManager* _Nonnull manager, 226 int forecastSeconds) __INTRODUCED_IN(31); 227 228 /** 229 * This struct defines an instance of headroom threshold value and its status. 230 * <p> 231 * The value should be monotonically non-decreasing as the thermal status increases. 232 * For {@link ATHERMAL_STATUS_SEVERE}, its headroom threshold is guaranteed to 233 * be 1.0f. For status below severe status, the value should be lower or equal 234 * to 1.0f, and for status above severe, the value should be larger or equal to 1.0f. 235 * <p> 236 * Also see {@link AThermal_getThermalHeadroom} for explanation on headroom, and 237 * {@link AThermal_getThermalHeadroomThresholds} for how to use this. 238 */ 239 struct AThermalHeadroomThreshold { 240 float headroom; 241 AThermalStatus thermalStatus; 242 }; 243 244 /** 245 * Gets the thermal headroom thresholds for all available thermal status. 246 * 247 * A thermal status will only exist in output if the device manufacturer has the 248 * corresponding threshold defined for at least one of its slow-moving skin temperature 249 * sensors. If it's set, one should also expect to get it from 250 * {@link #AThermal_getCurrentThermalStatus} or {@link AThermal_StatusCallback}. 251 * <p> 252 * The headroom threshold is used to interpret the possible thermal throttling status based on 253 * the headroom prediction. For example, if the headroom threshold for 254 * {@link ATHERMAL_STATUS_LIGHT} is 0.7, and a headroom prediction in 10s returns 0.75 255 * (or {@code AThermal_getThermalHeadroom(10)=0.75}), one can expect that in 10 seconds the system 256 * could be in lightly throttled state if the workload remains the same. The app can consider 257 * taking actions according to the nearest throttling status the difference between the headroom and 258 * the threshold. 259 * <p> 260 * For new devices it's guaranteed to have a single sensor, but for older devices with multiple 261 * sensors reporting different threshold values, the minimum threshold is taken to be conservative 262 * on predictions. Thus, when reading real-time headroom, it's not guaranteed that a real-time value 263 * of 0.75 (or {@code AThermal_getThermalHeadroom(0)}=0.75) exceeding the threshold of 0.7 above 264 * will always come with lightly throttled state 265 * (or {@code AThermal_getCurrentThermalStatus()=ATHERMAL_STATUS_LIGHT}) but it can be lower 266 * (or {@code AThermal_getCurrentThermalStatus()=ATHERMAL_STATUS_NONE}). 267 * While it's always guaranteed that the device won't be throttled heavier than the unmet 268 * threshold's state, so a real-time headroom of 0.75 will never come with 269 * {@link #ATHERMAL_STATUS_MODERATE} but always lower, and 0.65 will never come with 270 * {@link ATHERMAL_STATUS_LIGHT} but {@link #ATHERMAL_STATUS_NONE}. 271 * <p> 272 * The returned list of thresholds is cached on first successful query and owned by the thermal 273 * manager, which will not change between calls to this function. The caller should only need to 274 * free the manager with {@link AThermal_releaseManager}. 275 * 276 * @param manager The manager instance to use. 277 * Acquired via {@link AThermal_acquireManager}. 278 * @param outThresholds non-null output pointer to null AThermalHeadroomThreshold pointer, which 279 * will be set to the cached array of thresholds if thermal thresholds are supported 280 * by the system or device, otherwise nullptr or unmodified. 281 * @param size non-null output pointer whose value will be set to the size of the threshold array 282 * or 0 if it's not supported. 283 * @return 0 on success 284 * EINVAL if outThresholds or size_t is nullptr, or *outThresholds is not nullptr. 285 * EPIPE if communication with the system service has failed. 286 * ENOSYS if the feature is disabled by the current system. 287 */ 288 int AThermal_getThermalHeadroomThresholds(AThermalManager* _Nonnull manager, 289 const AThermalHeadroomThreshold* _Nonnull 290 * _Nullable outThresholds, 291 size_t* _Nonnull size) __INTRODUCED_IN(35); 292 293 #ifdef __cplusplus 294 } 295 #endif 296 297 #endif // _ANDROID_THERMAL_H 298 299 /** @} */ 300