Lines Matching +full:thermal +full:- +full:sensor
2 Generic Thermal Sysfs driver How To
15 The generic thermal sysfs provides a set of interfaces for thermal zone
16 devices (sensors) and thermal cooling devices (fan, processor...) to register
17 with the thermal management solution and to be a part of it.
19 This how-to focuses on enabling new thermal zone and cooling devices to
20 participate in thermal management.
21 This solution is platform independent and any type of thermal zone devices
24 The main task of the thermal sysfs driver is to expose thermal zone attributes
26 An intelligent thermal management application can make decisions based on
27 inputs from thermal zone attributes (the current temperature and trip point
30 - `[0-*]` denotes any positive number starting from 0
31 - `[1-*]` denotes any positive number starting from 1
33 1. thermal sysfs driver interface functions
36 1.1 thermal zone device interface
37 ---------------------------------
48 This interface function adds a new thermal zone device (sensor) to
49 /sys/class/thermal folder as `thermal_zone[0-*]`. It tries to bind all the
50 thermal cooling devices registered at the same time.
53 the thermal zone type.
55 the total number of trip points this thermal zone supports.
61 thermal zone device call-backs.
64 bind the thermal zone device with a thermal cooling device.
66 unbind the thermal zone device with a thermal cooling device.
68 get the current temperature of the thermal zone.
74 get the current mode (enabled/disabled) of the thermal zone.
76 - "enabled" means the kernel thermal management is
78 - "disabled" will prevent kernel thermal driver action
80 charge of thermal management.
82 set the mode (enabled/disabled) of the thermal zone.
92 thermal zone platform parameters.
104 This interface function removes the thermal zone device.
105 It deletes the corresponding entry from /sys/class/thermal folder and
106 unbinds all the thermal cooling devices it uses.
115 This interface adds a new sensor to a DT thermal zone.
116 This function will search the list of thermal zones described in
117 device tree and look for the zone that refer to the sensor device
118 pointed by dev->of_node as temperature providers. For the zone
119 pointing to the sensor node, the sensor will be added to the DT
120 thermal zone device.
125 Device node of sensor containing valid node pointer in
126 dev->of_node.
128 a sensor identifier, in case the sensor IP has more
138 sensor temperature. This is mandatory
139 callback provided by sensor driver.
142 left the driver must inform the thermal
145 sensor temperature trend.
147 sensor emulated temperature.
150 The thermal zone temperature is provided by the get_temp() function
154 It returns error pointer if fails otherwise valid thermal zone device
163 This interface unregisters a sensor from a DT thermal zone which was
165 This function removes the sensor callbacks and private data from the
166 thermal zone device registered with thermal_zone_of_sensor_register()
168 get_trend() thermal zone device callbacks.
184 The benefit of using this interface to register sensor is that it
206 for the thermal zone device, which might be useful for platform
214 for the thermal zone device, which might be useful for platform
217 1.2 thermal cooling device interface
218 ------------------------------------
227 This interface function adds a new thermal cooling device (fan/processor/...)
228 to /sys/class/thermal/ folder as `cooling_device[0-*]`. It tries to bind itself
229 to all the thermal zone devices registered at the same time.
236 thermal cooling devices call-backs.
250 This interface function removes the thermal cooling device.
251 It deletes the corresponding entry from /sys/class/thermal folder and
252 unbinds itself from all the thermal zone devices using it.
254 1.3 interface for binding a thermal zone device with a thermal cooling device
255 -----------------------------------------------------------------------------
263 This interface function binds a thermal cooling device to a particular trip
264 point of a thermal zone device.
266 This function is usually called in the thermal zone device .bind callback.
269 the thermal zone device
271 thermal cooling device
273 indicates which trip point in this thermal zone the cooling device
284 the influence of this cooling device in this thermal
292 This interface function unbinds a thermal cooling device from a particular
293 trip point of a thermal zone device. This function is usually called in
294 the thermal zone device .unbind callback.
297 the thermal zone device
299 thermal cooling device
301 indicates which trip point in this thermal zone the cooling device
304 1.4 Thermal Zone Parameters
305 ---------------------------
311 This structure defines the platform level parameters for a thermal zone.
312 This data, for each thermal zone should come from the platform layer.
317 Name of the thermal governor used for this zone
319 a boolean to indicate if the thermal to hwmon sysfs interface
334 Thermal sysfs attributes will be represented under /sys/class/thermal.
338 Thermal zone device sys I/F, created once it's registered::
340 /sys/class/thermal/thermal_zone[0-*]:
341 |---type: Type of the thermal zone
342 |---temp: Current temperature
343 |---mode: Working mode of the thermal zone
344 |---policy: Thermal governor used for this zone
345 |---available_policies: Available thermal governors for this zone
346 |---trip_point_[0-*]_temp: Trip point temperature
347 |---trip_point_[0-*]_type: Trip point type
348 |---trip_point_[0-*]_hyst: Hysteresis value for this trip point
349 |---emul_temp: Emulated temperature set node
350 |---sustainable_power: Sustainable dissipatable power
351 |---k_po: Proportional term during temperature overshoot
352 |---k_pu: Proportional term during temperature undershoot
353 |---k_i: PID's integral term in the power allocator gov
354 |---k_d: PID's derivative term in the power allocator
355 |---integral_cutoff: Offset above which errors are accumulated
356 |---slope: Slope constant applied as linear extrapolation
357 |---offset: Offset constant applied as linear extrapolation
359 Thermal cooling device sys I/F, created once it's registered::
361 /sys/class/thermal/cooling_device[0-*]:
362 |---type: Type of the cooling device(processor/fan/...)
363 |---max_state: Maximum cooling state of the cooling device
364 |---cur_state: Current cooling state of the cooling device
365 |---stats: Directory containing cooling device's statistics
366 |---stats/reset: Writing any value resets the statistics
367 |---stats/time_in_state_ms: Time (msec) spent in various cooling states
368 |---stats/total_trans: Total number of times cooling state is changed
369 |---stats/trans_table: Cooling state transition table
373 the relationship between a thermal zone and its associated cooling device.
379 /sys/class/thermal/thermal_zone[0-*]:
380 |---cdev[0-*]: [0-*]th cooling device in current thermal zone
381 |---cdev[0-*]_trip_point: Trip point that cdev[0-*] is associated with
382 |---cdev[0-*]_weight: Influence of the cooling device in
383 this thermal zone
385 Besides the thermal zone device sysfs I/F and cooling device sysfs I/F,
386 the generic thermal driver also creates a hwmon sysfs I/F for each _type_
387 of thermal zone device. E.g. the generic thermal driver registers one hwmon
389 ACPI thermal zones.
391 Please read Documentation/ABI/testing/sysfs-class-thermal for thermal
396 /sys/class/hwmon/hwmon[0-*]:
397 |---name: The type of the thermal zone devices
398 |---temp[1-*]_input: The current temperature of thermal zone [1-*]
399 |---temp[1-*]_critical: The critical trip point of thermal zone [1-*]
401 Please read Documentation/hwmon/sysfs-interface.rst for additional information.
406 ACPI thermal zone may support multiple trip points like critical, hot,
407 passive, active. If an ACPI thermal zone supports critical, passive,
412 effectiveness in cooling the thermal zone.
417 /sys/class/thermal:
419 |---type: acpitz
420 |---temp: 37000
421 |---mode: enabled
422 |---policy: step_wise
423 |---available_policies: step_wise fair_share
424 |---trip_point_0_temp: 100000
425 |---trip_point_0_type: critical
426 |---trip_point_1_temp: 80000
427 |---trip_point_1_type: passive
428 |---trip_point_2_temp: 70000
429 |---trip_point_2_type: active0
430 |---trip_point_3_temp: 60000
431 |---trip_point_3_type: active1
432 |---cdev0: --->/sys/class/thermal/cooling_device0
433 |---cdev0_trip_point: 1 /* cdev0 can be used for passive */
434 |---cdev0_weight: 1024
435 |---cdev1: --->/sys/class/thermal/cooling_device3
436 |---cdev1_trip_point: 2 /* cdev1 can be used for active[0]*/
437 |---cdev1_weight: 1024
440 |---type: Processor
441 |---max_state: 8
442 |---cur_state: 0
445 |---type: Fan
446 |---max_state: 2
447 |---cur_state: 0
451 |---name: acpitz
452 |---temp1_input: 37000
453 |---temp1_crit: 100000
459 -----------------
461 This function returns the trend of a thermal zone, i.e the rate of change
462 of temperature of the thermal zone. Ideally, the thermal sensor drivers
463 are supposed to implement the callback. If they don't, the thermal
468 -------------------------
475 ------------------------
484 On an event of critical trip temperature crossing the thermal framework
487 but accepts a delay after which it proceeds doing a forced power-off
494 carefully profiled non-zero positive value is a must for emergency