[PATCH v2] thermal: Move ABI documentation do Documentation/ABI
From: Mauro Carvalho Chehab
Date: Thu Oct 07 2021 - 04:25:53 EST
The thermal ABI is described, together with the internal
development details at:
Documentation/driver-api/thermal/sysfs-api.rst
Move the sysfs API description to Documentation/ABI,
ensuring that scripts/get_abi.pl will properly parse it.
While here, also update MAINTAINERS for it to point to
the documentation.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
---
Documentation/ABI/testing/sysfs-class-thermal | 259 ++++++++++++++++++
.../driver-api/thermal/sysfs-api.rst | 225 +--------------
MAINTAINERS | 2 +
3 files changed, 264 insertions(+), 222 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-class-thermal
diff --git a/Documentation/ABI/testing/sysfs-class-thermal b/Documentation/ABI/testing/sysfs-class-thermal
new file mode 100644
index 000000000000..2c52bb1f864c
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-thermal
@@ -0,0 +1,259 @@
+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
diff --git a/Documentation/driver-api/thermal/sysfs-api.rst b/Documentation/driver-api/thermal/sysfs-api.rst
index c93fa5e961a0..2e0f79a9e2ee 100644
--- a/Documentation/driver-api/thermal/sysfs-api.rst
+++ b/Documentation/driver-api/thermal/sysfs-api.rst
@@ -428,6 +428,9 @@ of thermal zone device. E.g. the generic thermal driver registers one hwmon
class device and build the associated hwmon sysfs I/F for all the registered
ACPI thermal zones.
+Please read Documentation/ABI/testing/sysfs-class-thermal for thermal
+zone and cooling device attribute details.
+
::
/sys/class/hwmon/hwmon[0-*]:
@@ -437,228 +440,6 @@ ACPI thermal zones.
Please read Documentation/hwmon/sysfs-interface.rst for additional information.
-Thermal zone attributes
------------------------
-
-type
- 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 should
- be a short, lowercase string, not containing spaces nor dashes.
- RO, Required
-
-temp
- Current temperature as reported by thermal zone (sensor).
- Unit: millidegree Celsius
- RO, Required
-
-mode
- 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
-
-policy
- One of the various thermal governors used for a particular zone.
-
- RW, Required
-
-available_policies
- Available thermal governors which can be used for a particular zone.
-
- RO, Required
-
-`trip_point_[0-*]_temp`
- The temperature above which trip point will be fired.
-
- Unit: millidegree Celsius
-
- RO, Optional
-
-`trip_point_[0-*]_type`
- 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
-
-`trip_point_[0-*]_hyst`
- The hysteresis value for a trip point, represented as an integer
- Unit: Celsius
- RW, Optional
-
-`cdev[0-*]`
- Sysfs link to the thermal cooling device node where the sys I/F
- for cooling device throttling control represents.
-
- RO, Optional
-
-`cdev[0-*]_trip_point`
- 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
-
-`cdev[0-*]_weight`
- 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
-
-emul_temp
- 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.
-
-sustainable_power
- 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
-
-k_po
- 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
-
-k_pu
- 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
-
-k_i
- 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
-
-k_d
- The derivative term of the power allocator governor's PID
- controller. For more information see
- Documentation/driver-api/thermal/power_allocator.rst
-
- RW, Optional
-
-integral_cutoff
- 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
-
-slope
- 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
-
-offset
- 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
-
-Cooling device attributes
--------------------------
-
-type
- 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
-
-max_state
- The maximum permissible cooling state of this cooling device.
-
- RO, Required
-
-cur_state
- 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
-
-stats/reset
- Writing any value resets the cooling device's statistics.
- WO, Required
-
-stats/time_in_state_ms:
- 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
-
-
-stats/total_trans:
- A single positive value showing the total number of times the state of a
- cooling device is changed.
-
- RO, Required
-
-stats/trans_table:
- 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
-
3. A simple implementation
==========================
diff --git a/MAINTAINERS b/MAINTAINERS
index 7cfd63ce7122..a8fa66402b05 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18697,7 +18697,9 @@ L: linux-pm@xxxxxxxxxxxxxxx
S: Supported
Q: https://patchwork.kernel.org/project/linux-pm/list/
T: git git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git thermal
+F: Documentation/ABI/testing/sysfs-class-thermal
F: Documentation/devicetree/bindings/thermal/
+F: Documentation/driver-api/thermal/
F: drivers/thermal/
F: include/linux/cpu_cooling.h
F: include/linux/thermal.h
--
2.31.1