Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 1 | Generic Thermal Sysfs driver How To |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 2 | =================================== |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 3 | |
| 4 | Written by Sujith Thomas <sujith.thomas@intel.com>, Zhang Rui <rui.zhang@intel.com> |
| 5 | |
| 6 | Updated: 2 January 2008 |
| 7 | |
| 8 | Copyright (c) 2008 Intel Corporation |
| 9 | |
| 10 | |
| 11 | 0. Introduction |
| 12 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 13 | The generic thermal sysfs provides a set of interfaces for thermal zone |
| 14 | devices (sensors) and thermal cooling devices (fan, processor...) to register |
| 15 | with the thermal management solution and to be a part of it. |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 16 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 17 | This how-to focuses on enabling new thermal zone and cooling devices to |
| 18 | participate in thermal management. |
| 19 | This solution is platform independent and any type of thermal zone devices |
| 20 | and cooling devices should be able to make use of the infrastructure. |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 21 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 22 | The main task of the thermal sysfs driver is to expose thermal zone attributes |
| 23 | as well as cooling device attributes to the user space. |
| 24 | An intelligent thermal management application can make decisions based on |
| 25 | inputs from thermal zone attributes (the current temperature and trip point |
| 26 | temperature) and throttle appropriate devices. |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 27 | |
| 28 | [0-*] denotes any positive number starting from 0 |
| 29 | [1-*] denotes any positive number starting from 1 |
| 30 | |
| 31 | 1. thermal sysfs driver interface functions |
| 32 | |
| 33 | 1.1 thermal zone device interface |
Zhang Rui | 514e6d2 | 2013-04-24 16:59:22 +0000 | [diff] [blame] | 34 | 1.1.1 struct thermal_zone_device *thermal_zone_device_register(char *type, |
Durgadoss R | c56f5c0 | 2012-07-25 10:10:58 +0800 | [diff] [blame] | 35 | int trips, int mask, void *devdata, |
Zhang Rui | 514e6d2 | 2013-04-24 16:59:22 +0000 | [diff] [blame] | 36 | struct thermal_zone_device_ops *ops, |
| 37 | const struct thermal_zone_params *tzp, |
| 38 | int passive_delay, int polling_delay)) |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 39 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 40 | This interface function adds a new thermal zone device (sensor) to |
| 41 | /sys/class/thermal folder as thermal_zone[0-*]. It tries to bind all the |
| 42 | thermal cooling devices registered at the same time. |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 43 | |
Zhang Rui | 514e6d2 | 2013-04-24 16:59:22 +0000 | [diff] [blame] | 44 | type: the thermal zone type. |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 45 | trips: the total number of trip points this thermal zone supports. |
Durgadoss R | c56f5c0 | 2012-07-25 10:10:58 +0800 | [diff] [blame] | 46 | mask: Bit string: If 'n'th bit is set, then trip point 'n' is writeable. |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 47 | devdata: device private data |
| 48 | ops: thermal zone device call-backs. |
| 49 | .bind: bind the thermal zone device with a thermal cooling device. |
| 50 | .unbind: unbind the thermal zone device with a thermal cooling device. |
| 51 | .get_temp: get the current temperature of the thermal zone. |
Zhang Rui | 8eaa8d6 | 2012-07-25 10:11:00 +0800 | [diff] [blame] | 52 | .get_mode: get the current mode (enabled/disabled) of the thermal zone. |
| 53 | - "enabled" means the kernel thermal management is enabled. |
| 54 | - "disabled" will prevent kernel thermal driver action upon trip points |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 55 | so that user applications can take charge of thermal management. |
Zhang Rui | 8eaa8d6 | 2012-07-25 10:11:00 +0800 | [diff] [blame] | 56 | .set_mode: set the mode (enabled/disabled) of the thermal zone. |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 57 | .get_trip_type: get the type of certain trip point. |
| 58 | .get_trip_temp: get the temperature above which the certain trip point |
| 59 | will be fired. |
Amit Daniel Kachhap | e6e238c | 2013-02-04 00:30:15 +0000 | [diff] [blame] | 60 | .set_emul_temp: set the emulation temperature which helps in debugging |
| 61 | different threshold temperature points. |
Zhang Rui | 514e6d2 | 2013-04-24 16:59:22 +0000 | [diff] [blame] | 62 | tzp: thermal zone platform parameters. |
| 63 | passive_delay: number of milliseconds to wait between polls when |
| 64 | performing passive cooling. |
| 65 | polling_delay: number of milliseconds to wait between polls when checking |
| 66 | whether trip points have been crossed (0 for interrupt driven systems). |
| 67 | |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 68 | |
| 69 | 1.1.2 void thermal_zone_device_unregister(struct thermal_zone_device *tz) |
| 70 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 71 | This interface function removes the thermal zone device. |
Andy Champ | c212ed9 | 2016-03-22 12:37:25 +0000 | [diff] [blame] | 72 | It deletes the corresponding entry from /sys/class/thermal folder and |
| 73 | unbinds all the thermal cooling devices it uses. |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 74 | |
Laxman Dewangan | 3a7fd9c | 2016-03-09 18:40:05 +0530 | [diff] [blame] | 75 | 1.1.3 struct thermal_zone_device *thermal_zone_of_sensor_register( |
| 76 | struct device *dev, int sensor_id, void *data, |
| 77 | const struct thermal_zone_of_device_ops *ops) |
| 78 | |
| 79 | This interface adds a new sensor to a DT thermal zone. |
| 80 | This function will search the list of thermal zones described in |
| 81 | device tree and look for the zone that refer to the sensor device |
| 82 | pointed by dev->of_node as temperature providers. For the zone |
| 83 | pointing to the sensor node, the sensor will be added to the DT |
| 84 | thermal zone device. |
| 85 | |
| 86 | The parameters for this interface are: |
| 87 | dev: Device node of sensor containing valid node pointer in |
| 88 | dev->of_node. |
| 89 | sensor_id: a sensor identifier, in case the sensor IP has more |
| 90 | than one sensors |
| 91 | data: a private pointer (owned by the caller) that will be |
| 92 | passed back, when a temperature reading is needed. |
| 93 | ops: struct thermal_zone_of_device_ops *. |
| 94 | |
| 95 | get_temp: a pointer to a function that reads the |
| 96 | sensor temperature. This is mandatory |
| 97 | callback provided by sensor driver. |
| 98 | get_trend: a pointer to a function that reads the |
| 99 | sensor temperature trend. |
| 100 | set_emul_temp: a pointer to a function that sets |
| 101 | sensor emulated temperature. |
| 102 | The thermal zone temperature is provided by the get_temp() function |
| 103 | pointer of thermal_zone_of_device_ops. When called, it will |
| 104 | have the private pointer @data back. |
| 105 | |
| 106 | It returns error pointer if fails otherwise valid thermal zone device |
| 107 | handle. Caller should check the return handle with IS_ERR() for finding |
| 108 | whether success or not. |
| 109 | |
| 110 | 1.1.4 void thermal_zone_of_sensor_unregister(struct device *dev, |
| 111 | struct thermal_zone_device *tzd) |
| 112 | |
| 113 | This interface unregisters a sensor from a DT thermal zone which was |
| 114 | successfully added by interface thermal_zone_of_sensor_register(). |
| 115 | This function removes the sensor callbacks and private data from the |
| 116 | thermal zone device registered with thermal_zone_of_sensor_register() |
| 117 | interface. It will also silent the zone by remove the .get_temp() and |
| 118 | get_trend() thermal zone device callbacks. |
| 119 | |
Laxman Dewangan | 61f846f | 2016-03-09 18:40:08 +0530 | [diff] [blame] | 120 | 1.1.5 struct thermal_zone_device *devm_thermal_zone_of_sensor_register( |
| 121 | struct device *dev, int sensor_id, |
| 122 | void *data, const struct thermal_zone_of_device_ops *ops) |
| 123 | |
| 124 | This interface is resource managed version of |
| 125 | thermal_zone_of_sensor_register(). |
| 126 | All details of thermal_zone_of_sensor_register() described in |
| 127 | section 1.1.3 is applicable here. |
| 128 | The benefit of using this interface to register sensor is that it |
| 129 | is not require to explicitly call thermal_zone_of_sensor_unregister() |
| 130 | in error path or during driver unbinding as this is done by driver |
| 131 | resource manager. |
| 132 | |
| 133 | 1.1.6 void devm_thermal_zone_of_sensor_unregister(struct device *dev, |
| 134 | struct thermal_zone_device *tzd) |
| 135 | |
| 136 | This interface is resource managed version of |
| 137 | thermal_zone_of_sensor_unregister(). |
| 138 | All details of thermal_zone_of_sensor_unregister() described in |
| 139 | section 1.1.4 is applicable here. |
| 140 | Normally this function will not need to be called and the resource |
| 141 | management code will ensure that the resource is freed. |
| 142 | |
Rajendra Nayak | 4a7069a | 2016-05-05 14:21:42 +0530 | [diff] [blame^] | 143 | 1.1.7 int thermal_zone_get_slope(struct thermal_zone_device *tz) |
| 144 | |
| 145 | This interface is used to read the slope attribute value |
| 146 | for the thermal zone device, which might be useful for platform |
| 147 | drivers for temperature calculations. |
| 148 | |
| 149 | 1.1.8 int thermal_zone_get_offset(struct thermal_zone_device *tz) |
| 150 | |
| 151 | This interface is used to read the offset attribute value |
| 152 | for the thermal zone device, which might be useful for platform |
| 153 | drivers for temperature calculations. |
| 154 | |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 155 | 1.2 thermal cooling device interface |
| 156 | 1.2.1 struct thermal_cooling_device *thermal_cooling_device_register(char *name, |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 157 | void *devdata, struct thermal_cooling_device_ops *) |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 158 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 159 | This interface function adds a new thermal cooling device (fan/processor/...) |
| 160 | to /sys/class/thermal/ folder as cooling_device[0-*]. It tries to bind itself |
Andy Champ | c212ed9 | 2016-03-22 12:37:25 +0000 | [diff] [blame] | 161 | to all the thermal zone devices registered at the same time. |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 162 | name: the cooling device name. |
| 163 | devdata: device private data. |
| 164 | ops: thermal cooling devices call-backs. |
| 165 | .get_max_state: get the Maximum throttle state of the cooling device. |
Andy Champ | c212ed9 | 2016-03-22 12:37:25 +0000 | [diff] [blame] | 166 | .get_cur_state: get the Currently requested throttle state of the cooling device. |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 167 | .set_cur_state: set the Current throttle state of the cooling device. |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 168 | |
| 169 | 1.2.2 void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev) |
| 170 | |
Andy Champ | c212ed9 | 2016-03-22 12:37:25 +0000 | [diff] [blame] | 171 | This interface function removes the thermal cooling device. |
| 172 | It deletes the corresponding entry from /sys/class/thermal folder and |
| 173 | unbinds itself from all the thermal zone devices using it. |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 174 | |
| 175 | 1.3 interface for binding a thermal zone device with a thermal cooling device |
| 176 | 1.3.1 int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz, |
Zhang Rui | 9d99842 | 2012-06-26 16:35:57 +0800 | [diff] [blame] | 177 | int trip, struct thermal_cooling_device *cdev, |
Kapileshwar Singh | 6cd9e9f | 2015-02-18 16:04:21 +0000 | [diff] [blame] | 178 | unsigned long upper, unsigned long lower, unsigned int weight); |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 179 | |
Andy Champ | c212ed9 | 2016-03-22 12:37:25 +0000 | [diff] [blame] | 180 | This interface function binds a thermal cooling device to a particular trip |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 181 | point of a thermal zone device. |
| 182 | This function is usually called in the thermal zone device .bind callback. |
| 183 | tz: the thermal zone device |
| 184 | cdev: thermal cooling device |
Andy Champ | c212ed9 | 2016-03-22 12:37:25 +0000 | [diff] [blame] | 185 | trip: indicates which trip point in this thermal zone the cooling device |
| 186 | is associated with. |
Zhang Rui | 9d99842 | 2012-06-26 16:35:57 +0800 | [diff] [blame] | 187 | upper:the Maximum cooling state for this trip point. |
| 188 | THERMAL_NO_LIMIT means no upper limit, |
| 189 | and the cooling device can be in max_state. |
| 190 | lower:the Minimum cooling state can be used for this trip point. |
| 191 | THERMAL_NO_LIMIT means no lower limit, |
| 192 | and the cooling device can be in cooling state 0. |
Kapileshwar Singh | 6cd9e9f | 2015-02-18 16:04:21 +0000 | [diff] [blame] | 193 | weight: the influence of this cooling device in this thermal |
| 194 | zone. See 1.4.1 below for more information. |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 195 | |
| 196 | 1.3.2 int thermal_zone_unbind_cooling_device(struct thermal_zone_device *tz, |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 197 | int trip, struct thermal_cooling_device *cdev); |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 198 | |
Andy Champ | c212ed9 | 2016-03-22 12:37:25 +0000 | [diff] [blame] | 199 | This interface function unbinds a thermal cooling device from a particular |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 200 | trip point of a thermal zone device. This function is usually called in |
| 201 | the thermal zone device .unbind callback. |
| 202 | tz: the thermal zone device |
| 203 | cdev: thermal cooling device |
Andy Champ | c212ed9 | 2016-03-22 12:37:25 +0000 | [diff] [blame] | 204 | trip: indicates which trip point in this thermal zone the cooling device |
| 205 | is associated with. |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 206 | |
Durgadoss R | 6ea083b | 2012-09-18 11:05:06 +0530 | [diff] [blame] | 207 | 1.4 Thermal Zone Parameters |
| 208 | 1.4.1 struct thermal_bind_params |
| 209 | This structure defines the following parameters that are used to bind |
| 210 | a zone with a cooling device for a particular trip point. |
| 211 | .cdev: The cooling device pointer |
Javi Merino | bcdcbbc | 2015-02-18 16:04:25 +0000 | [diff] [blame] | 212 | .weight: The 'influence' of a particular cooling device on this |
| 213 | zone. This is relative to the rest of the cooling |
| 214 | devices. For example, if all cooling devices have a |
| 215 | weight of 1, then they all contribute the same. You can |
| 216 | use percentages if you want, but it's not mandatory. A |
| 217 | weight of 0 means that this cooling device doesn't |
| 218 | contribute to the cooling of this zone unless all cooling |
| 219 | devices have a weight of 0. If all weights are 0, then |
| 220 | they all contribute the same. |
Durgadoss R | 6ea083b | 2012-09-18 11:05:06 +0530 | [diff] [blame] | 221 | .trip_mask:This is a bit mask that gives the binding relation between |
| 222 | this thermal zone and cdev, for a particular trip point. |
| 223 | If nth bit is set, then the cdev and thermal zone are bound |
| 224 | for trip point n. |
Andy Champ | c212ed9 | 2016-03-22 12:37:25 +0000 | [diff] [blame] | 225 | .binding_limits: This is an array of cooling state limits. Must have |
| 226 | exactly 2 * thermal_zone.number_of_trip_points. It is an |
| 227 | array consisting of tuples <lower-state upper-state> of |
| 228 | state limits. Each trip will be associated with one state |
| 229 | limit tuple when binding. A NULL pointer means |
| 230 | <THERMAL_NO_LIMITS THERMAL_NO_LIMITS> on all trips. |
| 231 | These limits are used when binding a cdev to a trip point. |
Durgadoss R | 6ea083b | 2012-09-18 11:05:06 +0530 | [diff] [blame] | 232 | .match: This call back returns success(0) if the 'tz and cdev' need to |
| 233 | be bound, as per platform data. |
| 234 | 1.4.2 struct thermal_zone_params |
| 235 | This structure defines the platform level parameters for a thermal zone. |
| 236 | This data, for each thermal zone should come from the platform layer. |
| 237 | This is an optional feature where some platforms can choose not to |
| 238 | provide this data. |
| 239 | .governor_name: Name of the thermal governor used for this zone |
Eduardo Valentin | ccba4ff | 2013-08-15 11:34:17 -0400 | [diff] [blame] | 240 | .no_hwmon: a boolean to indicate if the thermal to hwmon sysfs interface |
| 241 | is required. when no_hwmon == false, a hwmon sysfs interface |
| 242 | will be created. when no_hwmon == true, nothing will be done. |
| 243 | In case the thermal_zone_params is NULL, the hwmon interface |
| 244 | will be created (for backward compatibility). |
Durgadoss R | 6ea083b | 2012-09-18 11:05:06 +0530 | [diff] [blame] | 245 | .num_tbps: Number of thermal_bind_params entries for this zone |
| 246 | .tbp: thermal_bind_params entries |
| 247 | |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 248 | 2. sysfs attributes structure |
| 249 | |
| 250 | RO read only value |
| 251 | RW read/write value |
| 252 | |
Zhang Rui | e9ae710 | 2008-04-22 08:50:09 +0800 | [diff] [blame] | 253 | Thermal sysfs attributes will be represented under /sys/class/thermal. |
| 254 | Hwmon sysfs I/F extension is also available under /sys/class/hwmon |
| 255 | if hwmon is compiled in or built as a module. |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 256 | |
| 257 | Thermal zone device sys I/F, created once it's registered: |
Zhang Rui | e9ae710 | 2008-04-22 08:50:09 +0800 | [diff] [blame] | 258 | /sys/class/thermal/thermal_zone[0-*]: |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 259 | |---type: Type of the thermal zone |
| 260 | |---temp: Current temperature |
| 261 | |---mode: Working mode of the thermal zone |
Durgadoss R | 6ea083b | 2012-09-18 11:05:06 +0530 | [diff] [blame] | 262 | |---policy: Thermal governor used for this zone |
Ni Wade | 25a0a5c | 2015-07-14 15:40:56 +0800 | [diff] [blame] | 263 | |---available_policies: Available thermal governors for this zone |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 264 | |---trip_point_[0-*]_temp: Trip point temperature |
| 265 | |---trip_point_[0-*]_type: Trip point type |
Durgadoss R | 27365a6 | 2012-07-25 10:10:59 +0800 | [diff] [blame] | 266 | |---trip_point_[0-*]_hyst: Hysteresis value for this trip point |
Amit Daniel Kachhap | e6e238c | 2013-02-04 00:30:15 +0000 | [diff] [blame] | 267 | |---emul_temp: Emulated temperature set node |
Javi Merino | 9f38271 | 2015-03-26 15:53:02 +0000 | [diff] [blame] | 268 | |---sustainable_power: Sustainable dissipatable power |
| 269 | |---k_po: Proportional term during temperature overshoot |
| 270 | |---k_pu: Proportional term during temperature undershoot |
| 271 | |---k_i: PID's integral term in the power allocator gov |
| 272 | |---k_d: PID's derivative term in the power allocator |
| 273 | |---integral_cutoff: Offset above which errors are accumulated |
Eduardo Valentin | 9d0be7f | 2015-05-11 19:34:23 -0700 | [diff] [blame] | 274 | |---slope: Slope constant applied as linear extrapolation |
| 275 | |---offset: Offset constant applied as linear extrapolation |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 276 | |
| 277 | Thermal cooling device sys I/F, created once it's registered: |
Zhang Rui | e9ae710 | 2008-04-22 08:50:09 +0800 | [diff] [blame] | 278 | /sys/class/thermal/cooling_device[0-*]: |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 279 | |---type: Type of the cooling device(processor/fan/...) |
| 280 | |---max_state: Maximum cooling state of the cooling device |
| 281 | |---cur_state: Current cooling state of the cooling device |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 282 | |
| 283 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 284 | Then next two dynamic attributes are created/removed in pairs. They represent |
| 285 | the relationship between a thermal zone and its associated cooling device. |
| 286 | They are created/removed for each successful execution of |
| 287 | thermal_zone_bind_cooling_device/thermal_zone_unbind_cooling_device. |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 288 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 289 | /sys/class/thermal/thermal_zone[0-*]: |
| 290 | |---cdev[0-*]: [0-*]th cooling device in current thermal zone |
| 291 | |---cdev[0-*]_trip_point: Trip point that cdev[0-*] is associated with |
Javi Merino | db91651 | 2015-02-18 16:04:24 +0000 | [diff] [blame] | 292 | |---cdev[0-*]_weight: Influence of the cooling device in |
| 293 | this thermal zone |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 294 | |
Zhang Rui | e9ae710 | 2008-04-22 08:50:09 +0800 | [diff] [blame] | 295 | Besides the thermal zone device sysfs I/F and cooling device sysfs I/F, |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 296 | the generic thermal driver also creates a hwmon sysfs I/F for each _type_ |
| 297 | of thermal zone device. E.g. the generic thermal driver registers one hwmon |
| 298 | class device and build the associated hwmon sysfs I/F for all the registered |
| 299 | ACPI thermal zones. |
| 300 | |
Zhang Rui | e9ae710 | 2008-04-22 08:50:09 +0800 | [diff] [blame] | 301 | /sys/class/hwmon/hwmon[0-*]: |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 302 | |---name: The type of the thermal zone devices |
| 303 | |---temp[1-*]_input: The current temperature of thermal zone [1-*] |
| 304 | |---temp[1-*]_critical: The critical trip point of thermal zone [1-*] |
| 305 | |
Zhang Rui | e9ae710 | 2008-04-22 08:50:09 +0800 | [diff] [blame] | 306 | Please read Documentation/hwmon/sysfs-interface for additional information. |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 307 | |
| 308 | *************************** |
| 309 | * Thermal zone attributes * |
| 310 | *************************** |
| 311 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 312 | type |
| 313 | Strings which represent the thermal zone type. |
| 314 | This is given by thermal zone driver as part of registration. |
| 315 | E.g: "acpitz" indicates it's an ACPI thermal device. |
| 316 | In order to keep it consistent with hwmon sys attribute; this should |
| 317 | be a short, lowercase string, not containing spaces nor dashes. |
| 318 | RO, Required |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 319 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 320 | temp |
| 321 | Current temperature as reported by thermal zone (sensor). |
| 322 | Unit: millidegree Celsius |
| 323 | RO, Required |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 324 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 325 | mode |
Zhang Rui | 8eaa8d6 | 2012-07-25 10:11:00 +0800 | [diff] [blame] | 326 | One of the predefined values in [enabled, disabled]. |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 327 | This file gives information about the algorithm that is currently |
| 328 | managing the thermal zone. It can be either default kernel based |
| 329 | algorithm or user space application. |
Zhang Rui | 8eaa8d6 | 2012-07-25 10:11:00 +0800 | [diff] [blame] | 330 | enabled = enable Kernel Thermal management. |
| 331 | disabled = Preventing kernel thermal zone driver actions upon |
| 332 | trip points so that user application can take full |
| 333 | charge of the thermal management. |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 334 | RW, Optional |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 335 | |
Durgadoss R | 6ea083b | 2012-09-18 11:05:06 +0530 | [diff] [blame] | 336 | policy |
| 337 | One of the various thermal governors used for a particular zone. |
| 338 | RW, Required |
| 339 | |
Ni Wade | 25a0a5c | 2015-07-14 15:40:56 +0800 | [diff] [blame] | 340 | available_policies |
| 341 | Available thermal governors which can be used for a particular zone. |
| 342 | RO, Required |
| 343 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 344 | trip_point_[0-*]_temp |
| 345 | The temperature above which trip point will be fired. |
| 346 | Unit: millidegree Celsius |
| 347 | RO, Optional |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 348 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 349 | trip_point_[0-*]_type |
| 350 | Strings which indicate the type of the trip point. |
| 351 | E.g. it can be one of critical, hot, passive, active[0-*] for ACPI |
| 352 | thermal zone. |
| 353 | RO, Optional |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 354 | |
Durgadoss R | 27365a6 | 2012-07-25 10:10:59 +0800 | [diff] [blame] | 355 | trip_point_[0-*]_hyst |
| 356 | The hysteresis value for a trip point, represented as an integer |
| 357 | Unit: Celsius |
| 358 | RW, Optional |
| 359 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 360 | cdev[0-*] |
| 361 | Sysfs link to the thermal cooling device node where the sys I/F |
| 362 | for cooling device throttling control represents. |
| 363 | RO, Optional |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 364 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 365 | cdev[0-*]_trip_point |
Andy Champ | c212ed9 | 2016-03-22 12:37:25 +0000 | [diff] [blame] | 366 | The trip point in this thermal zone which cdev[0-*] is associated |
| 367 | with; -1 means the cooling device is not associated with any trip |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 368 | point. |
| 369 | RO, Optional |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 370 | |
Javi Merino | db91651 | 2015-02-18 16:04:24 +0000 | [diff] [blame] | 371 | cdev[0-*]_weight |
| 372 | The influence of cdev[0-*] in this thermal zone. This value |
| 373 | is relative to the rest of cooling devices in the thermal |
| 374 | zone. For example, if a cooling device has a weight double |
| 375 | than that of other, it's twice as effective in cooling the |
| 376 | thermal zone. |
| 377 | RW, Optional |
| 378 | |
Frans Pop | 29226ed | 2009-10-26 08:39:00 +0100 | [diff] [blame] | 379 | passive |
| 380 | Attribute is only present for zones in which the passive cooling |
| 381 | policy is not supported by native thermal driver. Default is zero |
| 382 | and can be set to a temperature (in millidegrees) to enable a |
| 383 | passive trip point for the zone. Activation is done by polling with |
| 384 | an interval of 1 second. |
| 385 | Unit: millidegrees Celsius |
Frans Pop | 3d8e3ad | 2009-10-26 08:39:02 +0100 | [diff] [blame] | 386 | Valid values: 0 (disabled) or greater than 1000 |
Frans Pop | 29226ed | 2009-10-26 08:39:00 +0100 | [diff] [blame] | 387 | RW, Optional |
| 388 | |
Amit Daniel Kachhap | e6e238c | 2013-02-04 00:30:15 +0000 | [diff] [blame] | 389 | emul_temp |
| 390 | Interface to set the emulated temperature method in thermal zone |
| 391 | (sensor). After setting this temperature, the thermal zone may pass |
| 392 | this temperature to platform emulation function if registered or |
| 393 | cache it locally. This is useful in debugging different temperature |
| 394 | threshold and its associated cooling action. This is write only node |
| 395 | and writing 0 on this node should disable emulation. |
| 396 | Unit: millidegree Celsius |
| 397 | WO, Optional |
| 398 | |
Eduardo Valentin | 8837295 | 2013-03-26 21:38:34 +0000 | [diff] [blame] | 399 | WARNING: Be careful while enabling this option on production systems, |
| 400 | because userland can easily disable the thermal policy by simply |
| 401 | flooding this sysfs node with low temperature values. |
| 402 | |
Javi Merino | 9f38271 | 2015-03-26 15:53:02 +0000 | [diff] [blame] | 403 | sustainable_power |
| 404 | An estimate of the sustained power that can be dissipated by |
| 405 | the thermal zone. Used by the power allocator governor. For |
| 406 | more information see Documentation/thermal/power_allocator.txt |
| 407 | Unit: milliwatts |
| 408 | RW, Optional |
| 409 | |
| 410 | k_po |
| 411 | The proportional term of the power allocator governor's PID |
| 412 | controller during temperature overshoot. Temperature overshoot |
| 413 | is when the current temperature is above the "desired |
| 414 | temperature" trip point. For more information see |
| 415 | Documentation/thermal/power_allocator.txt |
| 416 | RW, Optional |
| 417 | |
| 418 | k_pu |
| 419 | The proportional term of the power allocator governor's PID |
| 420 | controller during temperature undershoot. Temperature undershoot |
| 421 | is when the current temperature is below the "desired |
| 422 | temperature" trip point. For more information see |
| 423 | Documentation/thermal/power_allocator.txt |
| 424 | RW, Optional |
| 425 | |
| 426 | k_i |
| 427 | The integral term of the power allocator governor's PID |
| 428 | controller. This term allows the PID controller to compensate |
| 429 | for long term drift. For more information see |
| 430 | Documentation/thermal/power_allocator.txt |
| 431 | RW, Optional |
| 432 | |
| 433 | k_d |
| 434 | The derivative term of the power allocator governor's PID |
| 435 | controller. For more information see |
| 436 | Documentation/thermal/power_allocator.txt |
| 437 | RW, Optional |
| 438 | |
| 439 | integral_cutoff |
| 440 | Temperature offset from the desired temperature trip point |
| 441 | above which the integral term of the power allocator |
| 442 | governor's PID controller starts accumulating errors. For |
| 443 | example, if integral_cutoff is 0, then the integral term only |
| 444 | accumulates error when temperature is above the desired |
| 445 | temperature trip point. For more information see |
| 446 | Documentation/thermal/power_allocator.txt |
Leo Yan | ec3fc58 | 2016-01-13 15:21:05 +0800 | [diff] [blame] | 447 | Unit: millidegree Celsius |
Javi Merino | 9f38271 | 2015-03-26 15:53:02 +0000 | [diff] [blame] | 448 | RW, Optional |
| 449 | |
Eduardo Valentin | 9d0be7f | 2015-05-11 19:34:23 -0700 | [diff] [blame] | 450 | slope |
| 451 | The slope constant used in a linear extrapolation model |
| 452 | to determine a hotspot temperature based off the sensor's |
| 453 | raw readings. It is up to the device driver to determine |
| 454 | the usage of these values. |
| 455 | RW, Optional |
| 456 | |
| 457 | offset |
| 458 | The offset constant used in a linear extrapolation model |
| 459 | to determine a hotspot temperature based off the sensor's |
| 460 | raw readings. It is up to the device driver to determine |
| 461 | the usage of these values. |
| 462 | RW, Optional |
| 463 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 464 | ***************************** |
| 465 | * Cooling device attributes * |
| 466 | ***************************** |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 467 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 468 | type |
| 469 | String which represents the type of device, e.g: |
| 470 | - for generic ACPI: should be "Fan", "Processor" or "LCD" |
| 471 | - for memory controller device on intel_menlow platform: |
| 472 | should be "Memory controller". |
| 473 | RO, Required |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 474 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 475 | max_state |
| 476 | The maximum permissible cooling state of this cooling device. |
| 477 | RO, Required |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 478 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 479 | cur_state |
| 480 | The current cooling state of this cooling device. |
| 481 | The value can any integer numbers between 0 and max_state: |
| 482 | - cur_state == 0 means no cooling |
| 483 | - cur_state == max_state means the maximum cooling. |
| 484 | RW, Required |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 485 | |
| 486 | 3. A simple implementation |
| 487 | |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 488 | ACPI thermal zone may support multiple trip points like critical, hot, |
| 489 | passive, active. If an ACPI thermal zone supports critical, passive, |
| 490 | active[0] and active[1] at the same time, it may register itself as a |
| 491 | thermal_zone_device (thermal_zone1) with 4 trip points in all. |
| 492 | It has one processor and one fan, which are both registered as |
Javi Merino | db91651 | 2015-02-18 16:04:24 +0000 | [diff] [blame] | 493 | thermal_cooling_device. Both are considered to have the same |
| 494 | effectiveness in cooling the thermal zone. |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 495 | |
| 496 | If the processor is listed in _PSL method, and the fan is listed in _AL0 |
| 497 | method, the sys I/F structure will be built like this: |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 498 | |
| 499 | /sys/class/thermal: |
| 500 | |
| 501 | |thermal_zone1: |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 502 | |---type: acpitz |
| 503 | |---temp: 37000 |
Zhang Rui | 8eaa8d6 | 2012-07-25 10:11:00 +0800 | [diff] [blame] | 504 | |---mode: enabled |
Durgadoss R | 6ea083b | 2012-09-18 11:05:06 +0530 | [diff] [blame] | 505 | |---policy: step_wise |
Ni Wade | 25a0a5c | 2015-07-14 15:40:56 +0800 | [diff] [blame] | 506 | |---available_policies: step_wise fair_share |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 507 | |---trip_point_0_temp: 100000 |
| 508 | |---trip_point_0_type: critical |
| 509 | |---trip_point_1_temp: 80000 |
| 510 | |---trip_point_1_type: passive |
| 511 | |---trip_point_2_temp: 70000 |
| 512 | |---trip_point_2_type: active0 |
| 513 | |---trip_point_3_temp: 60000 |
| 514 | |---trip_point_3_type: active1 |
| 515 | |---cdev0: --->/sys/class/thermal/cooling_device0 |
| 516 | |---cdev0_trip_point: 1 /* cdev0 can be used for passive */ |
Javi Merino | db91651 | 2015-02-18 16:04:24 +0000 | [diff] [blame] | 517 | |---cdev0_weight: 1024 |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 518 | |---cdev1: --->/sys/class/thermal/cooling_device3 |
| 519 | |---cdev1_trip_point: 2 /* cdev1 can be used for active[0]*/ |
Javi Merino | db91651 | 2015-02-18 16:04:24 +0000 | [diff] [blame] | 520 | |---cdev1_weight: 1024 |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 521 | |
| 522 | |cooling_device0: |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 523 | |---type: Processor |
| 524 | |---max_state: 8 |
| 525 | |---cur_state: 0 |
Zhang Rui | 203d3d4 | 2008-01-17 15:51:08 +0800 | [diff] [blame] | 526 | |
| 527 | |cooling_device3: |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 528 | |---type: Fan |
| 529 | |---max_state: 2 |
| 530 | |---cur_state: 0 |
Zhang Rui | e9ae710 | 2008-04-22 08:50:09 +0800 | [diff] [blame] | 531 | |
| 532 | /sys/class/hwmon: |
| 533 | |
| 534 | |hwmon0: |
Frans Pop | 38bb084 | 2009-10-26 08:38:59 +0100 | [diff] [blame] | 535 | |---name: acpitz |
| 536 | |---temp1_input: 37000 |
| 537 | |---temp1_crit: 100000 |
R.Durgadoss | 4cb1872 | 2010-10-27 03:33:29 +0530 | [diff] [blame] | 538 | |
| 539 | 4. Event Notification |
| 540 | |
| 541 | The framework includes a simple notification mechanism, in the form of a |
| 542 | netlink event. Netlink socket initialization is done during the _init_ |
| 543 | of the framework. Drivers which intend to use the notification mechanism |
Jean Delvare | 2d58d7e | 2011-11-04 10:31:04 +0100 | [diff] [blame] | 544 | just need to call thermal_generate_netlink_event() with two arguments viz |
Eduardo Valentin | 8ab3e6a | 2013-01-02 15:29:39 +0000 | [diff] [blame] | 545 | (originator, event). The originator is a pointer to struct thermal_zone_device |
| 546 | from where the event has been originated. An integer which represents the |
| 547 | thermal zone device will be used in the message to identify the zone. The |
R.Durgadoss | 4cb1872 | 2010-10-27 03:33:29 +0530 | [diff] [blame] | 548 | event will be one of:{THERMAL_AUX0, THERMAL_AUX1, THERMAL_CRITICAL, |
| 549 | THERMAL_DEV_FAULT}. Notification can be sent when the current temperature |
| 550 | crosses any of the configured thresholds. |
Durgadoss R | 6ea083b | 2012-09-18 11:05:06 +0530 | [diff] [blame] | 551 | |
| 552 | 5. Export Symbol APIs: |
| 553 | |
| 554 | 5.1: get_tz_trend: |
| 555 | This function returns the trend of a thermal zone, i.e the rate of change |
| 556 | of temperature of the thermal zone. Ideally, the thermal sensor drivers |
| 557 | are supposed to implement the callback. If they don't, the thermal |
| 558 | framework calculated the trend by comparing the previous and the current |
| 559 | temperature values. |
| 560 | |
| 561 | 5.2:get_thermal_instance: |
| 562 | This function returns the thermal_instance corresponding to a given |
| 563 | {thermal_zone, cooling_device, trip_point} combination. Returns NULL |
| 564 | if such an instance does not exist. |
| 565 | |
Eduardo Valentin | 7b73c99 | 2013-04-23 21:48:14 +0000 | [diff] [blame] | 566 | 5.3:thermal_notify_framework: |
Durgadoss R | 6ea083b | 2012-09-18 11:05:06 +0530 | [diff] [blame] | 567 | This function handles the trip events from sensor drivers. It starts |
| 568 | throttling the cooling devices according to the policy configured. |
| 569 | For CRITICAL and HOT trip points, this notifies the respective drivers, |
| 570 | and does actual throttling for other trip points i.e ACTIVE and PASSIVE. |
| 571 | The throttling policy is based on the configured platform data; if no |
| 572 | platform data is provided, this uses the step_wise throttling policy. |
| 573 | |
| 574 | 5.4:thermal_cdev_update: |
| 575 | This function serves as an arbitrator to set the state of a cooling |
| 576 | device. It sets the cooling device to the deepest cooling state if |
| 577 | possible. |