e9ae71078b
Update the documentation for the thermal driver hwmon sys I/F. Change the ACPI thermal zone type to be consistent with hwmon. Signed-off-by: Zhang Rui <rui.zhang@intel.com> Acked-by: Jean Delvare <khali@linux-fr.org> Signed-off-by: Len Brown <len.brown@intel.com>
266 lines
10 KiB
Text
266 lines
10 KiB
Text
Generic Thermal Sysfs driver How To
|
|
=========================
|
|
|
|
Written by Sujith Thomas <sujith.thomas@intel.com>, Zhang Rui <rui.zhang@intel.com>
|
|
|
|
Updated: 2 January 2008
|
|
|
|
Copyright (c) 2008 Intel Corporation
|
|
|
|
|
|
0. Introduction
|
|
|
|
The generic thermal sysfs provides a set of interfaces for thermal zone devices (sensors)
|
|
and thermal cooling devices (fan, processor...) to register with the thermal management
|
|
solution and to be a part of it.
|
|
|
|
This how-to focuses on enabling new thermal zone and cooling devices to participate
|
|
in thermal management.
|
|
This solution is platform independent and any type of thermal zone devices and
|
|
cooling devices should be able to make use of the infrastructure.
|
|
|
|
The main task of the thermal sysfs driver is to expose thermal zone attributes as well
|
|
as cooling device attributes to the user space.
|
|
An intelligent thermal management application can make decisions based on inputs
|
|
from thermal zone attributes (the current temperature and trip point temperature)
|
|
and throttle appropriate devices.
|
|
|
|
[0-*] denotes any positive number starting from 0
|
|
[1-*] denotes any positive number starting from 1
|
|
|
|
1. thermal sysfs driver interface functions
|
|
|
|
1.1 thermal zone device interface
|
|
1.1.1 struct thermal_zone_device *thermal_zone_device_register(char *name, int trips,
|
|
void *devdata, struct thermal_zone_device_ops *ops)
|
|
|
|
This interface function adds a new thermal zone device (sensor) to
|
|
/sys/class/thermal folder as thermal_zone[0-*].
|
|
It tries to bind all the thermal cooling devices registered at the same time.
|
|
|
|
name: the thermal zone name.
|
|
trips: the total number of trip points this thermal zone supports.
|
|
devdata: device private data
|
|
ops: thermal zone device call-backs.
|
|
.bind: bind the thermal zone device with a thermal cooling device.
|
|
.unbind: unbind the thermal zone device with a thermal cooling device.
|
|
.get_temp: get the current temperature of the thermal zone.
|
|
.get_mode: get the current mode (user/kernel) of the thermal zone.
|
|
"kernel" means thermal management is done in kernel.
|
|
"user" will prevent kernel thermal driver actions upon trip points
|
|
so that user applications can take charge of thermal management.
|
|
.set_mode: set the mode (user/kernel) of the thermal zone.
|
|
.get_trip_type: get the type of certain trip point.
|
|
.get_trip_temp: get the temperature above which the certain trip point
|
|
will be fired.
|
|
|
|
1.1.2 void thermal_zone_device_unregister(struct thermal_zone_device *tz)
|
|
|
|
This interface function removes the thermal zone device.
|
|
It deletes the corresponding entry form /sys/class/thermal folder and unbind all
|
|
the thermal cooling devices it uses.
|
|
|
|
1.2 thermal cooling device interface
|
|
1.2.1 struct thermal_cooling_device *thermal_cooling_device_register(char *name,
|
|
void *devdata, struct thermal_cooling_device_ops *)
|
|
|
|
This interface function adds a new thermal cooling device (fan/processor/...) to
|
|
/sys/class/thermal/ folder as cooling_device[0-*].
|
|
It tries to bind itself to all the thermal zone devices register at the same time.
|
|
name: the cooling device name.
|
|
devdata: device private data.
|
|
ops: thermal cooling devices call-backs.
|
|
.get_max_state: get the Maximum throttle state of the cooling device.
|
|
.get_cur_state: get the Current throttle state of the cooling device.
|
|
.set_cur_state: set the Current throttle state of the cooling device.
|
|
|
|
1.2.2 void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev)
|
|
|
|
This interface function remove the thermal cooling device.
|
|
It deletes the corresponding entry form /sys/class/thermal folder and unbind
|
|
itself from all the thermal zone devices using it.
|
|
|
|
1.3 interface for binding a thermal zone device with a thermal cooling device
|
|
1.3.1 int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz,
|
|
int trip, struct thermal_cooling_device *cdev);
|
|
|
|
This interface function bind a thermal cooling device to the certain trip point
|
|
of a thermal zone device.
|
|
This function is usually called in the thermal zone device .bind callback.
|
|
tz: the thermal zone device
|
|
cdev: thermal cooling device
|
|
trip: indicates which trip point the cooling devices is associated with
|
|
in this thermal zone.
|
|
|
|
1.3.2 int thermal_zone_unbind_cooling_device(struct thermal_zone_device *tz,
|
|
int trip, struct thermal_cooling_device *cdev);
|
|
|
|
This interface function unbind a thermal cooling device from the certain trip point
|
|
of a thermal zone device.
|
|
This function is usually called in the thermal zone device .unbind callback.
|
|
tz: the thermal zone device
|
|
cdev: thermal cooling device
|
|
trip: indicates which trip point the cooling devices is associated with
|
|
in this thermal zone.
|
|
|
|
2. sysfs attributes structure
|
|
|
|
RO read only value
|
|
RW read/write value
|
|
|
|
Thermal sysfs attributes will be represented under /sys/class/thermal.
|
|
Hwmon sysfs I/F extension is also available under /sys/class/hwmon
|
|
if hwmon is compiled in or built as a module.
|
|
|
|
Thermal zone device sys I/F, created once it's registered:
|
|
/sys/class/thermal/thermal_zone[0-*]:
|
|
|-----type: Type of the thermal zone
|
|
|-----temp: Current temperature
|
|
|-----mode: Working mode of the thermal zone
|
|
|-----trip_point_[0-*]_temp: Trip point temperature
|
|
|-----trip_point_[0-*]_type: Trip point type
|
|
|
|
Thermal cooling device sys I/F, created once it's registered:
|
|
/sys/class/thermal/cooling_device[0-*]:
|
|
|-----type : Type of the cooling device(processor/fan/...)
|
|
|-----max_state: Maximum cooling state of the cooling device
|
|
|-----cur_state: Current cooling state of the cooling device
|
|
|
|
|
|
These two dynamic attributes are created/removed in pairs.
|
|
They represent the relationship between a thermal zone and its associated cooling device.
|
|
They are created/removed for each
|
|
thermal_zone_bind_cooling_device/thermal_zone_unbind_cooling_device successful execution.
|
|
|
|
/sys/class/thermal/thermal_zone[0-*]
|
|
|-----cdev[0-*]: The [0-*]th cooling device in the current thermal zone
|
|
|-----cdev[0-*]_trip_point: Trip point that cdev[0-*] is associated with
|
|
|
|
Besides the thermal zone device sysfs I/F and cooling device sysfs I/F,
|
|
the generic thermal driver also creates a hwmon sysfs I/F for each _type_ 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.
|
|
/sys/class/hwmon/hwmon[0-*]:
|
|
|-----name: The type of the thermal zone devices.
|
|
|-----temp[1-*]_input: The current temperature of thermal zone [1-*].
|
|
|-----temp[1-*]_critical: The critical trip point of thermal zone [1-*].
|
|
Please read Documentation/hwmon/sysfs-interface 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.
|
|
Eg: "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 [kernel, user]
|
|
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.
|
|
RW
|
|
Optional
|
|
kernel = Thermal management in kernel thermal zone driver.
|
|
user = Preventing kernel thermal zone driver actions upon
|
|
trip points so that user application can take full
|
|
charge of the thermal management.
|
|
|
|
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
|
|
|
|
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 with which cdev[0-*] is associated in this thermal zone
|
|
-1 means the cooling device is not associated with any trip point.
|
|
RO
|
|
Optional
|
|
|
|
******************************
|
|
* Cooling device attributes *
|
|
******************************
|
|
|
|
type String which represents the type of device
|
|
eg: For generic ACPI: this should be "Fan",
|
|
"Processor" or "LCD"
|
|
eg. For memory controller device on intel_menlow platform:
|
|
this 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
|
|
|
|
3. A simple implementation
|
|
|
|
ACPI thermal zone may support multiple trip points like critical/hot/passive/active.
|
|
If an ACPI thermal zone supports critical, passive, active[0] and active[1] at the same time,
|
|
it may register itself as a thermal_zone_device (thermal_zone1) with 4 trip points in all.
|
|
It has one processor and one fan, which are both registered as thermal_cooling_device.
|
|
If the processor is listed in _PSL method, and the fan is listed in _AL0 method,
|
|
the sys I/F structure will be built like this:
|
|
|
|
/sys/class/thermal:
|
|
|
|
|thermal_zone1:
|
|
|-----type: acpitz
|
|
|-----temp: 37000
|
|
|-----mode: kernel
|
|
|-----trip_point_0_temp: 100000
|
|
|-----trip_point_0_type: critical
|
|
|-----trip_point_1_temp: 80000
|
|
|-----trip_point_1_type: passive
|
|
|-----trip_point_2_temp: 70000
|
|
|-----trip_point_2_type: active0
|
|
|-----trip_point_3_temp: 60000
|
|
|-----trip_point_3_type: active1
|
|
|-----cdev0: --->/sys/class/thermal/cooling_device0
|
|
|-----cdev0_trip_point: 1 /* cdev0 can be used for passive */
|
|
|-----cdev1: --->/sys/class/thermal/cooling_device3
|
|
|-----cdev1_trip_point: 2 /* cdev1 can be used for active[0]*/
|
|
|
|
|cooling_device0:
|
|
|-----type: Processor
|
|
|-----max_state: 8
|
|
|-----cur_state: 0
|
|
|
|
|cooling_device3:
|
|
|-----type: Fan
|
|
|-----max_state: 2
|
|
|-----cur_state: 0
|
|
|
|
/sys/class/hwmon:
|
|
|
|
|hwmon0:
|
|
|-----name: acpitz
|
|
|-----temp1_input: 37000
|
|
|-----temp1_crit: 100000
|