xref: /openbmc/linux/Documentation/ABI/testing/sysfs-class-thermal (revision 80da1b50)

What:		/sys/class/thermal/thermal_zoneX/type
Description:
		Strings which represent the thermal zone type.
		This is given by thermal zone driver as part of registration.
		E.g: "acpitz" indicates it's an ACPI thermal device.
		In order to keep it consistent with hwmon sys attribute; this
		shouldbe a short, lowercase string, not containing spaces nor
		dashes.

		RO, Required

What:		/sys/class/thermal/thermal_zoneX/temp
Description:
		Current temperature as reported by thermal zone (sensor).

		Unit: millidegree Celsius

		RO, Required

What:		/sys/class/thermal/thermal_zoneX/mode
Description:
		One of the predefined values in [enabled, disabled].
		This file gives information about the algorithm that is
		currently managing the thermal zone. It can be either default
		kernel based algorithm or user space application.

		enabled
				enable Kernel Thermal management.
		disabled
				Preventing kernel thermal zone driver actions upon
				trip points so that user application can take full
				charge of the thermal management.

		RW, Optional

What:		/sys/class/thermal/thermal_zoneX/policy
Description:
		One of the various thermal governors used for a particular zone.

		RW, Required

What:		/sys/class/thermal/thermal_zoneX/available_policies
Description:
		Available thermal governors which can be used for a
		particular zone.

		RO, Required

What:		/sys/class/thermal/thermal_zoneX/trip_point_Y_temp
Description:
		The temperature above which trip point will be fired.

		Unit: millidegree Celsius

		RO, Optional

What:		/sys/class/thermal/thermal_zoneX/trip_point_Y_type
Description:
		Strings which indicate the type of the trip point.

		E.g. it can be one of critical, hot, passive, `active[0-*]`
		for ACPI thermal zone.

		RO, Optional

What:		/sys/class/thermal/thermal_zoneX/trip_point_Y_hyst
Description:
		The hysteresis value for a trip point, represented as an
		integer.

		Unit: Celsius

		RW, Optional

What:		/sys/class/thermal/thermal_zoneX/cdevY
Description:
	Sysfs link to the thermal cooling device node where the sys I/F
	for cooling device throttling control represents.

	RO, Optional

What:		/sys/class/thermal/thermal_zoneX/cdevY_trip_point
Description:
		The trip point in this thermal zone which `cdev[0-*]` is
		associated with; -1 means the cooling device is not
		associated with any trip point.

		RO, Optional

What:		/sys/class/thermal/thermal_zoneX/cdevY_weight
Description:
		The influence of `cdev[0-*]` in this thermal zone. This value
		is relative to the rest of cooling devices in the thermal
		zone. For example, if a cooling device has a weight double
		than that of other, it's twice as effective in cooling the
		thermal zone.

		RW, Optional

What:		/sys/class/thermal/thermal_zoneX/emul_temp
Description:
		Interface to set the emulated temperature method in thermal zone
		(sensor). After setting this temperature, the thermal zone may
		pass this temperature to platform emulation function if
		registered or cache it locally. This is useful in debugging
		different temperature threshold and its associated cooling
		action. This is write only node and writing 0 on this node
		should disable emulation.

		Unit: millidegree Celsius

		WO, Optional

		WARNING:
		    Be careful while enabling this option on production systems,
		    because userland can easily disable the thermal policy by simply
		    flooding this sysfs node with low temperature values.


What:		/sys/class/thermal/thermal_zoneX/k_d
Description:
		The derivative term of the power allocator governor's PID
		controller. For more information see
		Documentation/driver-api/thermal/power_allocator.rst

		RW, Optional

What:		/sys/class/thermal/thermal_zoneX/k_i
Description:
		The integral term of the power allocator governor's PID
		controller. This term allows the PID controller to compensate
		for long term drift. For more information see
		Documentation/driver-api/thermal/power_allocator.rst

		RW, Optional

What:		/sys/class/thermal/thermal_zoneX/k_po
Description:
		The proportional term of the power allocator governor's PID
		controller during temperature overshoot. Temperature overshoot
		is when the current temperature is above the "desired
		temperature" trip point. For more information see
		Documentation/driver-api/thermal/power_allocator.rst

		RW, Optional

What:		/sys/class/thermal/thermal_zoneX/k_pu
Description:
		The proportional term of the power allocator governor's PID
		controller during temperature undershoot. Temperature undershoot
		is when the current temperature is below the "desired
		temperature" trip point. For more information see
		Documentation/driver-api/thermal/power_allocator.rst

		RW, Optional

What:		/sys/class/thermal/thermal_zoneX/integral_cutoff
Description:
		Temperature offset from the desired temperature trip point
		above which the integral term of the power allocator
		governor's PID controller starts accumulating errors. For
		example, if integral_cutoff is 0, then the integral term only
		accumulates error when temperature is above the desired
		temperature trip point. For more information see
		Documentation/driver-api/thermal/power_allocator.rst

		Unit: millidegree Celsius

		RW, Optional

What:		/sys/class/thermal/thermal_zoneX/slope
Description:
		The slope constant used in a linear extrapolation model
		to determine a hotspot temperature based off the sensor's
		raw readings. It is up to the device driver to determine
		the usage of these values.

		RW, Optional

What:		/sys/class/thermal/thermal_zoneX/offset
Description:
		The offset constant used in a linear extrapolation model
		to determine a hotspot temperature based off the sensor's
		raw readings. It is up to the device driver to determine
		the usage of these values.

		RW, Optional

What:		/sys/class/thermal/thermal_zoneX/sustainable_power
Description:
		An estimate of the sustained power that can be dissipated by
		the thermal zone. Used by the power allocator governor. For
		more information see
		Documentation/driver-api/thermal/power_allocator.rst

		Unit: milliwatts

		RW, Optional

What:		/sys/class/thermal/cooling_deviceX/type
Description:
		String which represents the type of device, e.g:

		- for generic ACPI: should be "Fan", "Processor" or "LCD"
		- for memory controller device on intel_menlow platform:
		should be "Memory controller".

		RO, Required

What:		/sys/class/thermal/cooling_deviceX/max_state
Description:
		The maximum permissible cooling state of this cooling device.

		RO, Required

What:		/sys/class/thermal/cooling_deviceX/cur_state
Description:
		The current cooling state of this cooling device.
		The value can any integer numbers between 0 and max_state:

		- cur_state == 0 means no cooling
		- cur_state == max_state means the maximum cooling.

		RW, Required

What:		/sys/class/thermal/cooling_deviceX/stats/reset
Description:
		Writing any value resets the cooling device's statistics.

		WO, Required

What:		/sys/class/thermal/cooling_deviceX/stats/time_in_state_ms:
Description:
		The amount of time spent by the cooling device in various
		cooling states. The output will have "<state> <time>" pair
		in each line, which will mean this cooling device spent <time>
		msec of time at <state>.

		Output will have one line for each of the supported states.

		RO, Required

What:		/sys/class/thermal/cooling_deviceX/stats/total_trans
Description:
		A single positive value showing the total number of times
		the state of a cooling device is changed.

		RO, Required

What:		/sys/class/thermal/cooling_deviceX/stats/trans_table
Description:
		This gives fine grained information about all the cooling state
		transitions. The cat output here is a two dimensional matrix,
		where an entry <i,j> (row i, column j) represents the number
		of transitions from State_i to State_j. If the transition
		table is bigger than PAGE_SIZE, reading this will return
		an -EFBIG error.

		RO, Required