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Zhang Rui203d3d42008-01-17 15:51:08 +08001Generic Thermal Sysfs driver How To
Frans Pop38bb0842009-10-26 08:38:59 +01002===================================
Zhang Rui203d3d42008-01-17 15:51:08 +08003
4Written by Sujith Thomas <sujith.thomas@intel.com>, Zhang Rui <rui.zhang@intel.com>
5
6Updated: 2 January 2008
7
8Copyright (c) 2008 Intel Corporation
9
10
110. Introduction
12
Frans Pop38bb0842009-10-26 08:38:59 +010013The generic thermal sysfs provides a set of interfaces for thermal zone
14devices (sensors) and thermal cooling devices (fan, processor...) to register
15with the thermal management solution and to be a part of it.
Zhang Rui203d3d42008-01-17 15:51:08 +080016
Frans Pop38bb0842009-10-26 08:38:59 +010017This how-to focuses on enabling new thermal zone and cooling devices to
18participate in thermal management.
19This solution is platform independent and any type of thermal zone devices
20and cooling devices should be able to make use of the infrastructure.
Zhang Rui203d3d42008-01-17 15:51:08 +080021
Frans Pop38bb0842009-10-26 08:38:59 +010022The main task of the thermal sysfs driver is to expose thermal zone attributes
23as well as cooling device attributes to the user space.
24An intelligent thermal management application can make decisions based on
25inputs from thermal zone attributes (the current temperature and trip point
26temperature) and throttle appropriate devices.
Zhang Rui203d3d42008-01-17 15:51:08 +080027
28[0-*] denotes any positive number starting from 0
29[1-*] denotes any positive number starting from 1
30
311. thermal sysfs driver interface functions
32
331.1 thermal zone device interface
Zhang Rui514e6d22013-04-24 16:59:22 +0000341.1.1 struct thermal_zone_device *thermal_zone_device_register(char *type,
Durgadoss Rc56f5c02012-07-25 10:10:58 +080035 int trips, int mask, void *devdata,
Zhang Rui514e6d22013-04-24 16:59:22 +000036 struct thermal_zone_device_ops *ops,
37 const struct thermal_zone_params *tzp,
38 int passive_delay, int polling_delay))
Zhang Rui203d3d42008-01-17 15:51:08 +080039
Frans Pop38bb0842009-10-26 08:38:59 +010040 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 Rui203d3d42008-01-17 15:51:08 +080043
Zhang Rui514e6d22013-04-24 16:59:22 +000044 type: the thermal zone type.
Frans Pop38bb0842009-10-26 08:38:59 +010045 trips: the total number of trip points this thermal zone supports.
Durgadoss Rc56f5c02012-07-25 10:10:58 +080046 mask: Bit string: If 'n'th bit is set, then trip point 'n' is writeable.
Frans Pop38bb0842009-10-26 08:38:59 +010047 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 Rui8eaa8d62012-07-25 10:11:00 +080052 .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 Pop38bb0842009-10-26 08:38:59 +010055 so that user applications can take charge of thermal management.
Zhang Rui8eaa8d62012-07-25 10:11:00 +080056 .set_mode: set the mode (enabled/disabled) of the thermal zone.
Frans Pop38bb0842009-10-26 08:38:59 +010057 .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 Kachhape6e238c2013-02-04 00:30:15 +000060 .set_emul_temp: set the emulation temperature which helps in debugging
61 different threshold temperature points.
Zhang Rui514e6d22013-04-24 16:59:22 +000062 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 Rui203d3d42008-01-17 15:51:08 +080068
691.1.2 void thermal_zone_device_unregister(struct thermal_zone_device *tz)
70
Frans Pop38bb0842009-10-26 08:38:59 +010071 This interface function removes the thermal zone device.
72 It deletes the corresponding entry form /sys/class/thermal folder and
73 unbind all the thermal cooling devices it uses.
Zhang Rui203d3d42008-01-17 15:51:08 +080074
751.2 thermal cooling device interface
761.2.1 struct thermal_cooling_device *thermal_cooling_device_register(char *name,
Frans Pop38bb0842009-10-26 08:38:59 +010077 void *devdata, struct thermal_cooling_device_ops *)
Zhang Rui203d3d42008-01-17 15:51:08 +080078
Frans Pop38bb0842009-10-26 08:38:59 +010079 This interface function adds a new thermal cooling device (fan/processor/...)
80 to /sys/class/thermal/ folder as cooling_device[0-*]. It tries to bind itself
81 to all the thermal zone devices register at the same time.
82 name: the cooling device name.
83 devdata: device private data.
84 ops: thermal cooling devices call-backs.
85 .get_max_state: get the Maximum throttle state of the cooling device.
86 .get_cur_state: get the Current throttle state of the cooling device.
87 .set_cur_state: set the Current throttle state of the cooling device.
Zhang Rui203d3d42008-01-17 15:51:08 +080088
891.2.2 void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev)
90
Frans Pop38bb0842009-10-26 08:38:59 +010091 This interface function remove the thermal cooling device.
92 It deletes the corresponding entry form /sys/class/thermal folder and
93 unbind itself from all the thermal zone devices using it.
Zhang Rui203d3d42008-01-17 15:51:08 +080094
951.3 interface for binding a thermal zone device with a thermal cooling device
961.3.1 int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz,
Zhang Rui9d998422012-06-26 16:35:57 +080097 int trip, struct thermal_cooling_device *cdev,
Kapileshwar Singh6cd9e9f2015-02-18 16:04:21 +000098 unsigned long upper, unsigned long lower, unsigned int weight);
Zhang Rui203d3d42008-01-17 15:51:08 +080099
Frans Pop38bb0842009-10-26 08:38:59 +0100100 This interface function bind a thermal cooling device to the certain trip
101 point of a thermal zone device.
102 This function is usually called in the thermal zone device .bind callback.
103 tz: the thermal zone device
104 cdev: thermal cooling device
105 trip: indicates which trip point the cooling devices is associated with
106 in this thermal zone.
Zhang Rui9d998422012-06-26 16:35:57 +0800107 upper:the Maximum cooling state for this trip point.
108 THERMAL_NO_LIMIT means no upper limit,
109 and the cooling device can be in max_state.
110 lower:the Minimum cooling state can be used for this trip point.
111 THERMAL_NO_LIMIT means no lower limit,
112 and the cooling device can be in cooling state 0.
Kapileshwar Singh6cd9e9f2015-02-18 16:04:21 +0000113 weight: the influence of this cooling device in this thermal
114 zone. See 1.4.1 below for more information.
Zhang Rui203d3d42008-01-17 15:51:08 +0800115
1161.3.2 int thermal_zone_unbind_cooling_device(struct thermal_zone_device *tz,
Frans Pop38bb0842009-10-26 08:38:59 +0100117 int trip, struct thermal_cooling_device *cdev);
Zhang Rui203d3d42008-01-17 15:51:08 +0800118
Frans Pop38bb0842009-10-26 08:38:59 +0100119 This interface function unbind a thermal cooling device from the certain
120 trip point of a thermal zone device. This function is usually called in
121 the thermal zone device .unbind callback.
122 tz: the thermal zone device
123 cdev: thermal cooling device
124 trip: indicates which trip point the cooling devices is associated with
125 in this thermal zone.
Zhang Rui203d3d42008-01-17 15:51:08 +0800126
Durgadoss R6ea083b2012-09-18 11:05:06 +05301271.4 Thermal Zone Parameters
1281.4.1 struct thermal_bind_params
129 This structure defines the following parameters that are used to bind
130 a zone with a cooling device for a particular trip point.
131 .cdev: The cooling device pointer
Javi Merinobcdcbbc2015-02-18 16:04:25 +0000132 .weight: The 'influence' of a particular cooling device on this
133 zone. This is relative to the rest of the cooling
134 devices. For example, if all cooling devices have a
135 weight of 1, then they all contribute the same. You can
136 use percentages if you want, but it's not mandatory. A
137 weight of 0 means that this cooling device doesn't
138 contribute to the cooling of this zone unless all cooling
139 devices have a weight of 0. If all weights are 0, then
140 they all contribute the same.
Durgadoss R6ea083b2012-09-18 11:05:06 +0530141 .trip_mask:This is a bit mask that gives the binding relation between
142 this thermal zone and cdev, for a particular trip point.
143 If nth bit is set, then the cdev and thermal zone are bound
144 for trip point n.
Eduardo Valentina8892d832013-07-16 15:26:28 -0400145 .limits: This is an array of cooling state limits. Must have exactly
146 2 * thermal_zone.number_of_trip_points. It is an array consisting
147 of tuples <lower-state upper-state> of state limits. Each trip
148 will be associated with one state limit tuple when binding.
149 A NULL pointer means <THERMAL_NO_LIMITS THERMAL_NO_LIMITS>
150 on all trips. These limits are used when binding a cdev to a
151 trip point.
Durgadoss R6ea083b2012-09-18 11:05:06 +0530152 .match: This call back returns success(0) if the 'tz and cdev' need to
153 be bound, as per platform data.
1541.4.2 struct thermal_zone_params
155 This structure defines the platform level parameters for a thermal zone.
156 This data, for each thermal zone should come from the platform layer.
157 This is an optional feature where some platforms can choose not to
158 provide this data.
159 .governor_name: Name of the thermal governor used for this zone
Eduardo Valentinccba4ff2013-08-15 11:34:17 -0400160 .no_hwmon: a boolean to indicate if the thermal to hwmon sysfs interface
161 is required. when no_hwmon == false, a hwmon sysfs interface
162 will be created. when no_hwmon == true, nothing will be done.
163 In case the thermal_zone_params is NULL, the hwmon interface
164 will be created (for backward compatibility).
Durgadoss R6ea083b2012-09-18 11:05:06 +0530165 .num_tbps: Number of thermal_bind_params entries for this zone
166 .tbp: thermal_bind_params entries
167
Zhang Rui203d3d42008-01-17 15:51:08 +08001682. sysfs attributes structure
169
170RO read only value
171RW read/write value
172
Zhang Ruie9ae7102008-04-22 08:50:09 +0800173Thermal sysfs attributes will be represented under /sys/class/thermal.
174Hwmon sysfs I/F extension is also available under /sys/class/hwmon
175if hwmon is compiled in or built as a module.
Zhang Rui203d3d42008-01-17 15:51:08 +0800176
177Thermal zone device sys I/F, created once it's registered:
Zhang Ruie9ae7102008-04-22 08:50:09 +0800178/sys/class/thermal/thermal_zone[0-*]:
Frans Pop38bb0842009-10-26 08:38:59 +0100179 |---type: Type of the thermal zone
180 |---temp: Current temperature
181 |---mode: Working mode of the thermal zone
Durgadoss R6ea083b2012-09-18 11:05:06 +0530182 |---policy: Thermal governor used for this zone
Ni Wade25a0a5c2015-07-14 15:40:56 +0800183 |---available_policies: Available thermal governors for this zone
Frans Pop38bb0842009-10-26 08:38:59 +0100184 |---trip_point_[0-*]_temp: Trip point temperature
185 |---trip_point_[0-*]_type: Trip point type
Durgadoss R27365a62012-07-25 10:10:59 +0800186 |---trip_point_[0-*]_hyst: Hysteresis value for this trip point
Amit Daniel Kachhape6e238c2013-02-04 00:30:15 +0000187 |---emul_temp: Emulated temperature set node
Javi Merino9f382712015-03-26 15:53:02 +0000188 |---sustainable_power: Sustainable dissipatable power
189 |---k_po: Proportional term during temperature overshoot
190 |---k_pu: Proportional term during temperature undershoot
191 |---k_i: PID's integral term in the power allocator gov
192 |---k_d: PID's derivative term in the power allocator
193 |---integral_cutoff: Offset above which errors are accumulated
Eduardo Valentin9d0be7f2015-05-11 19:34:23 -0700194 |---slope: Slope constant applied as linear extrapolation
195 |---offset: Offset constant applied as linear extrapolation
Zhang Rui203d3d42008-01-17 15:51:08 +0800196
197Thermal cooling device sys I/F, created once it's registered:
Zhang Ruie9ae7102008-04-22 08:50:09 +0800198/sys/class/thermal/cooling_device[0-*]:
Frans Pop38bb0842009-10-26 08:38:59 +0100199 |---type: Type of the cooling device(processor/fan/...)
200 |---max_state: Maximum cooling state of the cooling device
201 |---cur_state: Current cooling state of the cooling device
Zhang Rui203d3d42008-01-17 15:51:08 +0800202
203
Frans Pop38bb0842009-10-26 08:38:59 +0100204Then next two dynamic attributes are created/removed in pairs. They represent
205the relationship between a thermal zone and its associated cooling device.
206They are created/removed for each successful execution of
207thermal_zone_bind_cooling_device/thermal_zone_unbind_cooling_device.
Zhang Rui203d3d42008-01-17 15:51:08 +0800208
Frans Pop38bb0842009-10-26 08:38:59 +0100209/sys/class/thermal/thermal_zone[0-*]:
210 |---cdev[0-*]: [0-*]th cooling device in current thermal zone
211 |---cdev[0-*]_trip_point: Trip point that cdev[0-*] is associated with
Javi Merinodb916512015-02-18 16:04:24 +0000212 |---cdev[0-*]_weight: Influence of the cooling device in
213 this thermal zone
Zhang Rui203d3d42008-01-17 15:51:08 +0800214
Zhang Ruie9ae7102008-04-22 08:50:09 +0800215Besides the thermal zone device sysfs I/F and cooling device sysfs I/F,
Frans Pop38bb0842009-10-26 08:38:59 +0100216the generic thermal driver also creates a hwmon sysfs I/F for each _type_
217of thermal zone device. E.g. the generic thermal driver registers one hwmon
218class device and build the associated hwmon sysfs I/F for all the registered
219ACPI thermal zones.
220
Zhang Ruie9ae7102008-04-22 08:50:09 +0800221/sys/class/hwmon/hwmon[0-*]:
Frans Pop38bb0842009-10-26 08:38:59 +0100222 |---name: The type of the thermal zone devices
223 |---temp[1-*]_input: The current temperature of thermal zone [1-*]
224 |---temp[1-*]_critical: The critical trip point of thermal zone [1-*]
225
Zhang Ruie9ae7102008-04-22 08:50:09 +0800226Please read Documentation/hwmon/sysfs-interface for additional information.
Zhang Rui203d3d42008-01-17 15:51:08 +0800227
228***************************
229* Thermal zone attributes *
230***************************
231
Frans Pop38bb0842009-10-26 08:38:59 +0100232type
233 Strings which represent the thermal zone type.
234 This is given by thermal zone driver as part of registration.
235 E.g: "acpitz" indicates it's an ACPI thermal device.
236 In order to keep it consistent with hwmon sys attribute; this should
237 be a short, lowercase string, not containing spaces nor dashes.
238 RO, Required
Zhang Rui203d3d42008-01-17 15:51:08 +0800239
Frans Pop38bb0842009-10-26 08:38:59 +0100240temp
241 Current temperature as reported by thermal zone (sensor).
242 Unit: millidegree Celsius
243 RO, Required
Zhang Rui203d3d42008-01-17 15:51:08 +0800244
Frans Pop38bb0842009-10-26 08:38:59 +0100245mode
Zhang Rui8eaa8d62012-07-25 10:11:00 +0800246 One of the predefined values in [enabled, disabled].
Frans Pop38bb0842009-10-26 08:38:59 +0100247 This file gives information about the algorithm that is currently
248 managing the thermal zone. It can be either default kernel based
249 algorithm or user space application.
Zhang Rui8eaa8d62012-07-25 10:11:00 +0800250 enabled = enable Kernel Thermal management.
251 disabled = Preventing kernel thermal zone driver actions upon
252 trip points so that user application can take full
253 charge of the thermal management.
Frans Pop38bb0842009-10-26 08:38:59 +0100254 RW, Optional
Zhang Rui203d3d42008-01-17 15:51:08 +0800255
Durgadoss R6ea083b2012-09-18 11:05:06 +0530256policy
257 One of the various thermal governors used for a particular zone.
258 RW, Required
259
Ni Wade25a0a5c2015-07-14 15:40:56 +0800260available_policies
261 Available thermal governors which can be used for a particular zone.
262 RO, Required
263
Frans Pop38bb0842009-10-26 08:38:59 +0100264trip_point_[0-*]_temp
265 The temperature above which trip point will be fired.
266 Unit: millidegree Celsius
267 RO, Optional
Zhang Rui203d3d42008-01-17 15:51:08 +0800268
Frans Pop38bb0842009-10-26 08:38:59 +0100269trip_point_[0-*]_type
270 Strings which indicate the type of the trip point.
271 E.g. it can be one of critical, hot, passive, active[0-*] for ACPI
272 thermal zone.
273 RO, Optional
Zhang Rui203d3d42008-01-17 15:51:08 +0800274
Durgadoss R27365a62012-07-25 10:10:59 +0800275trip_point_[0-*]_hyst
276 The hysteresis value for a trip point, represented as an integer
277 Unit: Celsius
278 RW, Optional
279
Frans Pop38bb0842009-10-26 08:38:59 +0100280cdev[0-*]
281 Sysfs link to the thermal cooling device node where the sys I/F
282 for cooling device throttling control represents.
283 RO, Optional
Zhang Rui203d3d42008-01-17 15:51:08 +0800284
Frans Pop38bb0842009-10-26 08:38:59 +0100285cdev[0-*]_trip_point
286 The trip point with which cdev[0-*] is associated in this thermal
287 zone; -1 means the cooling device is not associated with any trip
288 point.
289 RO, Optional
Zhang Rui203d3d42008-01-17 15:51:08 +0800290
Javi Merinodb916512015-02-18 16:04:24 +0000291cdev[0-*]_weight
292 The influence of cdev[0-*] in this thermal zone. This value
293 is relative to the rest of cooling devices in the thermal
294 zone. For example, if a cooling device has a weight double
295 than that of other, it's twice as effective in cooling the
296 thermal zone.
297 RW, Optional
298
Frans Pop29226ed2009-10-26 08:39:00 +0100299passive
300 Attribute is only present for zones in which the passive cooling
301 policy is not supported by native thermal driver. Default is zero
302 and can be set to a temperature (in millidegrees) to enable a
303 passive trip point for the zone. Activation is done by polling with
304 an interval of 1 second.
305 Unit: millidegrees Celsius
Frans Pop3d8e3ad2009-10-26 08:39:02 +0100306 Valid values: 0 (disabled) or greater than 1000
Frans Pop29226ed2009-10-26 08:39:00 +0100307 RW, Optional
308
Amit Daniel Kachhape6e238c2013-02-04 00:30:15 +0000309emul_temp
310 Interface to set the emulated temperature method in thermal zone
311 (sensor). After setting this temperature, the thermal zone may pass
312 this temperature to platform emulation function if registered or
313 cache it locally. This is useful in debugging different temperature
314 threshold and its associated cooling action. This is write only node
315 and writing 0 on this node should disable emulation.
316 Unit: millidegree Celsius
317 WO, Optional
318
Eduardo Valentin88372952013-03-26 21:38:34 +0000319 WARNING: Be careful while enabling this option on production systems,
320 because userland can easily disable the thermal policy by simply
321 flooding this sysfs node with low temperature values.
322
Javi Merino9f382712015-03-26 15:53:02 +0000323sustainable_power
324 An estimate of the sustained power that can be dissipated by
325 the thermal zone. Used by the power allocator governor. For
326 more information see Documentation/thermal/power_allocator.txt
327 Unit: milliwatts
328 RW, Optional
329
330k_po
331 The proportional term of the power allocator governor's PID
332 controller during temperature overshoot. Temperature overshoot
333 is when the current temperature is above the "desired
334 temperature" trip point. For more information see
335 Documentation/thermal/power_allocator.txt
336 RW, Optional
337
338k_pu
339 The proportional term of the power allocator governor's PID
340 controller during temperature undershoot. Temperature undershoot
341 is when the current temperature is below the "desired
342 temperature" trip point. For more information see
343 Documentation/thermal/power_allocator.txt
344 RW, Optional
345
346k_i
347 The integral term of the power allocator governor's PID
348 controller. This term allows the PID controller to compensate
349 for long term drift. For more information see
350 Documentation/thermal/power_allocator.txt
351 RW, Optional
352
353k_d
354 The derivative term of the power allocator governor's PID
355 controller. For more information see
356 Documentation/thermal/power_allocator.txt
357 RW, Optional
358
359integral_cutoff
360 Temperature offset from the desired temperature trip point
361 above which the integral term of the power allocator
362 governor's PID controller starts accumulating errors. For
363 example, if integral_cutoff is 0, then the integral term only
364 accumulates error when temperature is above the desired
365 temperature trip point. For more information see
366 Documentation/thermal/power_allocator.txt
367 RW, Optional
368
Eduardo Valentin9d0be7f2015-05-11 19:34:23 -0700369slope
370 The slope constant used in a linear extrapolation model
371 to determine a hotspot temperature based off the sensor's
372 raw readings. It is up to the device driver to determine
373 the usage of these values.
374 RW, Optional
375
376offset
377 The offset constant used in a linear extrapolation model
378 to determine a hotspot temperature based off the sensor's
379 raw readings. It is up to the device driver to determine
380 the usage of these values.
381 RW, Optional
382
Frans Pop38bb0842009-10-26 08:38:59 +0100383*****************************
384* Cooling device attributes *
385*****************************
Zhang Rui203d3d42008-01-17 15:51:08 +0800386
Frans Pop38bb0842009-10-26 08:38:59 +0100387type
388 String which represents the type of device, e.g:
389 - for generic ACPI: should be "Fan", "Processor" or "LCD"
390 - for memory controller device on intel_menlow platform:
391 should be "Memory controller".
392 RO, Required
Zhang Rui203d3d42008-01-17 15:51:08 +0800393
Frans Pop38bb0842009-10-26 08:38:59 +0100394max_state
395 The maximum permissible cooling state of this cooling device.
396 RO, Required
Zhang Rui203d3d42008-01-17 15:51:08 +0800397
Frans Pop38bb0842009-10-26 08:38:59 +0100398cur_state
399 The current cooling state of this cooling device.
400 The value can any integer numbers between 0 and max_state:
401 - cur_state == 0 means no cooling
402 - cur_state == max_state means the maximum cooling.
403 RW, Required
Zhang Rui203d3d42008-01-17 15:51:08 +0800404
4053. A simple implementation
406
Frans Pop38bb0842009-10-26 08:38:59 +0100407ACPI thermal zone may support multiple trip points like critical, hot,
408passive, active. If an ACPI thermal zone supports critical, passive,
409active[0] and active[1] at the same time, it may register itself as a
410thermal_zone_device (thermal_zone1) with 4 trip points in all.
411It has one processor and one fan, which are both registered as
Javi Merinodb916512015-02-18 16:04:24 +0000412thermal_cooling_device. Both are considered to have the same
413effectiveness in cooling the thermal zone.
Frans Pop38bb0842009-10-26 08:38:59 +0100414
415If the processor is listed in _PSL method, and the fan is listed in _AL0
416method, the sys I/F structure will be built like this:
Zhang Rui203d3d42008-01-17 15:51:08 +0800417
418/sys/class/thermal:
419
420|thermal_zone1:
Frans Pop38bb0842009-10-26 08:38:59 +0100421 |---type: acpitz
422 |---temp: 37000
Zhang Rui8eaa8d62012-07-25 10:11:00 +0800423 |---mode: enabled
Durgadoss R6ea083b2012-09-18 11:05:06 +0530424 |---policy: step_wise
Ni Wade25a0a5c2015-07-14 15:40:56 +0800425 |---available_policies: step_wise fair_share
Frans Pop38bb0842009-10-26 08:38:59 +0100426 |---trip_point_0_temp: 100000
427 |---trip_point_0_type: critical
428 |---trip_point_1_temp: 80000
429 |---trip_point_1_type: passive
430 |---trip_point_2_temp: 70000
431 |---trip_point_2_type: active0
432 |---trip_point_3_temp: 60000
433 |---trip_point_3_type: active1
434 |---cdev0: --->/sys/class/thermal/cooling_device0
435 |---cdev0_trip_point: 1 /* cdev0 can be used for passive */
Javi Merinodb916512015-02-18 16:04:24 +0000436 |---cdev0_weight: 1024
Frans Pop38bb0842009-10-26 08:38:59 +0100437 |---cdev1: --->/sys/class/thermal/cooling_device3
438 |---cdev1_trip_point: 2 /* cdev1 can be used for active[0]*/
Javi Merinodb916512015-02-18 16:04:24 +0000439 |---cdev1_weight: 1024
Zhang Rui203d3d42008-01-17 15:51:08 +0800440
441|cooling_device0:
Frans Pop38bb0842009-10-26 08:38:59 +0100442 |---type: Processor
443 |---max_state: 8
444 |---cur_state: 0
Zhang Rui203d3d42008-01-17 15:51:08 +0800445
446|cooling_device3:
Frans Pop38bb0842009-10-26 08:38:59 +0100447 |---type: Fan
448 |---max_state: 2
449 |---cur_state: 0
Zhang Ruie9ae7102008-04-22 08:50:09 +0800450
451/sys/class/hwmon:
452
453|hwmon0:
Frans Pop38bb0842009-10-26 08:38:59 +0100454 |---name: acpitz
455 |---temp1_input: 37000
456 |---temp1_crit: 100000
R.Durgadoss4cb18722010-10-27 03:33:29 +0530457
4584. Event Notification
459
460The framework includes a simple notification mechanism, in the form of a
461netlink event. Netlink socket initialization is done during the _init_
462of the framework. Drivers which intend to use the notification mechanism
Jean Delvare2d58d7e2011-11-04 10:31:04 +0100463just need to call thermal_generate_netlink_event() with two arguments viz
Eduardo Valentin8ab3e6a2013-01-02 15:29:39 +0000464(originator, event). The originator is a pointer to struct thermal_zone_device
465from where the event has been originated. An integer which represents the
466thermal zone device will be used in the message to identify the zone. The
R.Durgadoss4cb18722010-10-27 03:33:29 +0530467event will be one of:{THERMAL_AUX0, THERMAL_AUX1, THERMAL_CRITICAL,
468THERMAL_DEV_FAULT}. Notification can be sent when the current temperature
469crosses any of the configured thresholds.
Durgadoss R6ea083b2012-09-18 11:05:06 +0530470
4715. Export Symbol APIs:
472
4735.1: get_tz_trend:
474This function returns the trend of a thermal zone, i.e the rate of change
475of temperature of the thermal zone. Ideally, the thermal sensor drivers
476are supposed to implement the callback. If they don't, the thermal
477framework calculated the trend by comparing the previous and the current
478temperature values.
479
4805.2:get_thermal_instance:
481This function returns the thermal_instance corresponding to a given
482{thermal_zone, cooling_device, trip_point} combination. Returns NULL
483if such an instance does not exist.
484
Eduardo Valentin7b73c992013-04-23 21:48:14 +00004855.3:thermal_notify_framework:
Durgadoss R6ea083b2012-09-18 11:05:06 +0530486This function handles the trip events from sensor drivers. It starts
487throttling the cooling devices according to the policy configured.
488For CRITICAL and HOT trip points, this notifies the respective drivers,
489and does actual throttling for other trip points i.e ACTIVE and PASSIVE.
490The throttling policy is based on the configured platform data; if no
491platform data is provided, this uses the step_wise throttling policy.
492
4935.4:thermal_cdev_update:
494This function serves as an arbitrator to set the state of a cooling
495device. It sets the cooling device to the deepest cooling state if
496possible.