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docs: thermal: convert to ReST 

Rename the thermal documentation files to ReST, add an
index for them and adjust in order to produce a nice html
output via the Sphinx build system.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
This commit is contained in:
Mauro Carvalho Chehab 2019-06-18 18:05:28 -03:00 committed by Zhang Rui
parent 57c5b2ec90
commit 6bbe6f5732
12 changed files with 695 additions and 430 deletions
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39
Documentation/thermal/cpu-cooling-api.txt → Documentation/thermal/cpu-cooling-api.rst
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@ -1,5 +1,6 @@
=======================
CPU cooling APIs How To
===================================
=======================
Written by Amit Daniel Kachhap <amit.kachhap@linaro.org>
@ -8,40 +9,54 @@ Updated: 6 Jan 2015
Copyright (c) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
0. Introduction
===============
The generic cpu cooling(freq clipping) provides registration/unregistration APIs
to the caller. The binding of the cooling devices to the trip point is left for
the user. The registration APIs returns the cooling device pointer.
1. cpu cooling APIs
===================
1.1 cpufreq registration/unregistration APIs
1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
struct cpumask *clip_cpus)
--------------------------------------------
::
struct thermal_cooling_device
*cpufreq_cooling_register(struct cpumask *clip_cpus)
This interface function registers the cpufreq cooling device with the name
"thermal-cpufreq-%x". This api can support multiple instances of cpufreq
cooling devices.
clip_cpus: cpumask of cpus where the frequency constraints will happen.
clip_cpus:
cpumask of cpus where the frequency constraints will happen.
1.1.2 struct thermal_cooling_device *of_cpufreq_cooling_register(
struct cpufreq_policy *policy)
::
struct thermal_cooling_device
*of_cpufreq_cooling_register(struct cpufreq_policy *policy)
This interface function registers the cpufreq cooling device with
the name "thermal-cpufreq-%x" linking it with a device tree node, in
order to bind it via the thermal DT code. This api can support multiple
instances of cpufreq cooling devices.
policy: CPUFreq policy.
policy:
CPUFreq policy.
1.1.3 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
::
void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
This interface function unregisters the "thermal-cpufreq-%x" cooling device.
cdev: Cooling device pointer which has to be unregistered.
2. Power models
===============
The power API registration functions provide a simple power model for
CPUs. The current power is calculated as dynamic power (static power isn't
@ -65,9 +80,9 @@ For a given processor implementation the primary factors are:
variation. In pathological cases this variation can be significant,
but typically it is of a much lesser impact than the factors above.
A high level dynamic power consumption model may then be represented as:
A high level dynamic power consumption model may then be represented as::
Pdyn = f(run) * Voltage^2 * Frequency * Utilisation
Pdyn = f(run) * Voltage^2 * Frequency * Utilisation
f(run) here represents the described execution behaviour and its
result has a units of Watts/Hz/Volt^2 (this often expressed in
@ -80,9 +95,9 @@ factors. Therefore, in initial implementation that contribution is
represented as a constant coefficient. This is a simplification
consistent with the relative contribution to overall power variation.
In this simplified representation our model becomes:
In this simplified representation our model becomes::
Pdyn = Capacitance * Voltage^2 * Frequency * Utilisation
Pdyn = Capacitance * Voltage^2 * Frequency * Utilisation
Where `capacitance` is a constant that represents an indicative
running time dynamic power coefficient in fundamental units of

47
Documentation/thermal/exynos_thermal → Documentation/thermal/exynos_thermal.rst
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@ -1,8 +1,11 @@
========================
Kernel driver exynos_tmu
=================
========================
Supported chips:
* ARM SAMSUNG EXYNOS4, EXYNOS5 series of SoC
Datasheet: Not publicly available
Authors: Donggeun Kim <dg77.kim@samsung.com>
@ -19,32 +22,39 @@ Temperature can be taken from the temperature code.
There are three equations converting from temperature to temperature code.
The three equations are:
1. Two point trimming
1. Two point trimming::
Tc = (T - 25) * (TI2 - TI1) / (85 - 25) + TI1
2. One point trimming
2. One point trimming::
Tc = T + TI1 - 25
3. No trimming
3. No trimming::
Tc = T + 50
Tc: Temperature code, T: Temperature,
TI1: Trimming info for 25 degree Celsius (stored at TRIMINFO register)
Tc:
Temperature code, T: Temperature,
TI1:
Trimming info for 25 degree Celsius (stored at TRIMINFO register)
Temperature code measured at 25 degree Celsius which is unchanged
TI2: Trimming info for 85 degree Celsius (stored at TRIMINFO register)
TI2:
Trimming info for 85 degree Celsius (stored at TRIMINFO register)
Temperature code measured at 85 degree Celsius which is unchanged
TMU(Thermal Management Unit) in EXYNOS4/5 generates interrupt
when temperature exceeds pre-defined levels.
The maximum number of configurable threshold is five.
The threshold levels are defined as follows:
The threshold levels are defined as follows::
Level_0: current temperature > trigger_level_0 + threshold
Level_1: current temperature > trigger_level_1 + threshold
Level_2: current temperature > trigger_level_2 + threshold
Level_3: current temperature > trigger_level_3 + threshold
The threshold and each trigger_level are set
through the corresponding registers.
The threshold and each trigger_level are set
through the corresponding registers.
When an interrupt occurs, this driver notify kernel thermal framework
with the function exynos_report_trigger.
@ -54,24 +64,27 @@ it can be used to synchronize the cooling action.
TMU driver description:
-----------------------
The exynos thermal driver is structured as,
The exynos thermal driver is structured as::
Kernel Core thermal framework
(thermal_core.c, step_wise.c, cpu_cooling.c)
^
|
|
TMU configuration data -------> TMU Driver <------> Exynos Core thermal wrapper
(exynos_tmu_data.c) (exynos_tmu.c) (exynos_thermal_common.c)
(exynos_tmu_data.h) (exynos_tmu.h) (exynos_thermal_common.h)
TMU configuration data -----> TMU Driver <----> Exynos Core thermal wrapper
(exynos_tmu_data.c) (exynos_tmu.c) (exynos_thermal_common.c)
(exynos_tmu_data.h) (exynos_tmu.h) (exynos_thermal_common.h)
a) TMU configuration data: This consist of TMU register offsets/bitfields
a) TMU configuration data:
This consist of TMU register offsets/bitfields
described through structure exynos_tmu_registers. Also several
other platform data (struct exynos_tmu_platform_data) members
are used to configure the TMU.
b) TMU driver: This component initialises the TMU controller and sets different
b) TMU driver:
This component initialises the TMU controller and sets different
thresholds. It invokes core thermal implementation with the call
exynos_report_trigger.
c) Exynos Core thermal wrapper: This provides 3 wrapper function to use the
c) Exynos Core thermal wrapper:
This provides 3 wrapper function to use the
Kernel core thermal framework. They are exynos_unregister_thermal,
exynos_register_thermal and exynos_report_trigger.

53
Documentation/thermal/exynos_thermal_emulation
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@ -1,53 +0,0 @@
EXYNOS EMULATION MODE
========================
Copyright (C) 2012 Samsung Electronics
Written by Jonghwa Lee <jonghwa3.lee@samsung.com>
Description
-----------
Exynos 4x12 (4212, 4412) and 5 series provide emulation mode for thermal management unit.
Thermal emulation mode supports software debug for TMU's operation. User can set temperature
manually with software code and TMU will read current temperature from user value not from
sensor's value.
Enabling CONFIG_THERMAL_EMULATION option will make this support available.
When it's enabled, sysfs node will be created as
/sys/devices/virtual/thermal/thermal_zone'zone id'/emul_temp.
The sysfs node, 'emul_node', will contain value 0 for the initial state. When you input any
temperature you want to update to sysfs node, it automatically enable emulation mode and
current temperature will be changed into it.
(Exynos also supports user changeable delay time which would be used to delay of
changing temperature. However, this node only uses same delay of real sensing time, 938us.)
Exynos emulation mode requires synchronous of value changing and enabling. It means when you
want to update the any value of delay or next temperature, then you have to enable emulation
mode at the same time. (Or you have to keep the mode enabling.) If you don't, it fails to
change the value to updated one and just use last succeessful value repeatedly. That's why
this node gives users the right to change termerpature only. Just one interface makes it more
simply to use.
Disabling emulation mode only requires writing value 0 to sysfs node.
TEMP 120 |
|
100 |
|
80 |
| +-----------
60 | | |
| +-------------| |
40 | | | |
| | | |
20 | | | +----------
| | | | |
0 |______________|_____________|__________|__________|_________
A A A A TIME
|<----->| |<----->| |<----->| |
| 938us | | | | | |
emulation : 0 50 | 70 | 20 | 0
current temp : sensor 50 70 20 sensor

61
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@ -0,0 +1,61 @@
=====================
Exynos Emulation Mode
=====================
Copyright (C) 2012 Samsung Electronics
Written by Jonghwa Lee <jonghwa3.lee@samsung.com>
Description
-----------
Exynos 4x12 (4212, 4412) and 5 series provide emulation mode for thermal
management unit. Thermal emulation mode supports software debug for
TMU's operation. User can set temperature manually with software code
and TMU will read current temperature from user value not from sensor's
value.
Enabling CONFIG_THERMAL_EMULATION option will make this support
available. When it's enabled, sysfs node will be created as
/sys/devices/virtual/thermal/thermal_zone'zone id'/emul_temp.
The sysfs node, 'emul_node', will contain value 0 for the initial state.
When you input any temperature you want to update to sysfs node, it
automatically enable emulation mode and current temperature will be
changed into it.
(Exynos also supports user changeable delay time which would be used to
delay of changing temperature. However, this node only uses same delay
of real sensing time, 938us.)
Exynos emulation mode requires synchronous of value changing and
enabling. It means when you want to update the any value of delay or
next temperature, then you have to enable emulation mode at the same
time. (Or you have to keep the mode enabling.) If you don't, it fails to
change the value to updated one and just use last succeessful value
repeatedly. That's why this node gives users the right to change
termerpature only. Just one interface makes it more simply to use.
Disabling emulation mode only requires writing value 0 to sysfs node.
::
TEMP 120 |
|
100 |
|
80 |
| +-----------
60 | | |
| +-------------| |
40 | | | |
| | | |
20 | | | +----------
| | | | |
0 |______________|_____________|__________|__________|_________
A A A A TIME
|<----->| |<----->| |<----->| |
| 938us | | | | | |
emulation : 0 50 | 70 | 20 | 0
current temp: sensor 50 70 20 sensor

18
Documentation/thermal/index.rst Normal file
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@ -0,0 +1,18 @@
:orphan:
=======
Thermal
=======
.. toctree::
:maxdepth: 1
cpu-cooling-api
sysfs-api
power_allocator
exynos_thermal
exynos_thermal_emulation
intel_powerclamp
nouveau_thermal
x86_pkg_temperature_thermal

177
Documentation/thermal/intel_powerclamp.txt → Documentation/thermal/intel_powerclamp.rst
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@ -1,10 +1,13 @@
=======================
INTEL POWERCLAMP DRIVER
=======================
By: Arjan van de Ven <arjan@linux.intel.com>
Jacob Pan <jacob.jun.pan@linux.intel.com>
=======================
Intel Powerclamp Driver
=======================
By:
- Arjan van de Ven <arjan@linux.intel.com>
- Jacob Pan <jacob.jun.pan@linux.intel.com>
.. Contents:
Contents:
(*) Introduction
- Goals and Objectives
@ -23,7 +26,6 @@ Contents:
- Generic Thermal Layer (sysfs)
- Kernel APIs (TBD)
============
INTRODUCTION
============
@ -47,7 +49,6 @@ scalability, and user experience. In many cases, clear advantage is
shown over taking the CPU offline or modulating the CPU clock.
===================
THEORY OF OPERATION
===================
@ -57,11 +58,12 @@ Idle Injection
On modern Intel processors (Nehalem or later), package level C-state
residency is available in MSRs, thus also available to the kernel.
These MSRs are:
#define MSR_PKG_C2_RESIDENCY 0x60D
#define MSR_PKG_C3_RESIDENCY 0x3F8
#define MSR_PKG_C6_RESIDENCY 0x3F9
#define MSR_PKG_C7_RESIDENCY 0x3FA
These MSRs are::
#define MSR_PKG_C2_RESIDENCY 0x60D
#define MSR_PKG_C3_RESIDENCY 0x3F8
#define MSR_PKG_C6_RESIDENCY 0x3F9
#define MSR_PKG_C7_RESIDENCY 0x3FA
If the kernel can also inject idle time to the system, then a
closed-loop control system can be established that manages package
@ -96,19 +98,21 @@ are not masked. Tests show that the extra wakeups from scheduler tick
have a dramatic impact on the effectiveness of the powerclamp driver
on large scale systems (Westmere system with 80 processors).
CPU0
____________ ____________
kidle_inject/0 | sleep | mwait | sleep |
_________| |________| |_______
duration
CPU1
____________ ____________
kidle_inject/1 | sleep | mwait | sleep |
_________| |________| |_______
^
|
|
roundup(jiffies, interval)
::
CPU0
____________ ____________
kidle_inject/0 | sleep | mwait | sleep |
_________| |________| |_______
duration
CPU1
____________ ____________
kidle_inject/1 | sleep | mwait | sleep |
_________| |________| |_______
^
|
|
roundup(jiffies, interval)
Only one CPU is allowed to collect statistics and update global
control parameters. This CPU is referred to as the controlling CPU in
@ -148,7 +152,7 @@ b) determine the amount of compensation needed at each target ratio
Compensation to each target ratio consists of two parts:
a) steady state error compensation
a) steady state error compensation
This is to offset the error occurring when the system can
enter idle without extra wakeups (such as external interrupts).
@ -158,41 +162,42 @@ Compensation to each target ratio consists of two parts:
slowing down CPU activities.
A debugfs file is provided for the user to examine compensation
progress and results, such as on a Westmere system.
[jacob@nex01 ~]$ cat
/sys/kernel/debug/intel_powerclamp/powerclamp_calib
controlling cpu: 0
pct confidence steady dynamic (compensation)
0 0 0 0
1 1 0 0
2 1 1 0
3 3 1 0
4 3 1 0
5 3 1 0
6 3 1 0
7 3 1 0
8 3 1 0
...
30 3 2 0
31 3 2 0
32 3 1 0
33 3 2 0
34 3 1 0
35 3 2 0
36 3 1 0
37 3 2 0
38 3 1 0
39 3 2 0
40 3 3 0
41 3 1 0
42 3 2 0
43 3 1 0
44 3 1 0
45 3 2 0
46 3 3 0
47 3 0 0
48 3 2 0
49 3 3 0
progress and results, such as on a Westmere system::
[jacob@nex01 ~]$ cat
/sys/kernel/debug/intel_powerclamp/powerclamp_calib
controlling cpu: 0
pct confidence steady dynamic (compensation)
0 0 0 0
1 1 0 0
2 1 1 0
3 3 1 0
4 3 1 0
5 3 1 0
6 3 1 0
7 3 1 0
8 3 1 0
...
30 3 2 0
31 3 2 0
32 3 1 0
33 3 2 0
34 3 1 0
35 3 2 0
36 3 1 0
37 3 2 0
38 3 1 0
39 3 2 0
40 3 3 0
41 3 1 0
42 3 2 0
43 3 1 0
44 3 1 0
45 3 2 0
46 3 3 0
47 3 0 0
48 3 2 0
49 3 3 0
Calibration occurs during runtime. No offline method is available.
Steady state compensation is used only when confidence levels of all
@ -217,9 +222,8 @@ keeps track of clamping kernel threads, even after they are migrated
to other CPUs, after a CPU offline event.
=====================
Performance Analysis
=====================
====================
This section describes the general performance data collected on
multiple systems, including Westmere (80P) and Ivy Bridge (4P, 8P).
@ -257,16 +261,15 @@ achieve up to 40% better performance per watt. (measured by a spin
counter summed over per CPU counting threads spawned for all running
CPUs).
====================
Usage and Interfaces
====================
The powerclamp driver is registered to the generic thermal layer as a
cooling device. Currently, it’s not bound to any thermal zones.
cooling device. Currently, it’s not bound to any thermal zones::
jacob@chromoly:/sys/class/thermal/cooling_device14$ grep . *
cur_state:0
max_state:50
type:intel_powerclamp
jacob@chromoly:/sys/class/thermal/cooling_device14$ grep . *
cur_state:0
max_state:50
type:intel_powerclamp
cur_state allows user to set the desired idle percentage. Writing 0 to
cur_state will stop idle injection. Writing a value between 1 and
@ -278,9 +281,9 @@ cur_state returns value -1 instead of 0 which is to avoid confusing
100% busy state with the disabled state.
Example usage:
- To inject 25% idle time
$ sudo sh -c "echo 25 > /sys/class/thermal/cooling_device80/cur_state
"
- To inject 25% idle time::
$ sudo sh -c "echo 25 > /sys/class/thermal/cooling_device80/cur_state
If the system is not busy and has more than 25% idle time already,
then the powerclamp driver will not start idle injection. Using Top
@ -292,23 +295,23 @@ idle time is accounted as normal idle in that common code path is
taken as the idle task.
In this example, 24.1% idle is shown. This helps the system admin or
user determine the cause of slowdown, when a powerclamp driver is in action.
user determine the cause of slowdown, when a powerclamp driver is in action::
Tasks: 197 total, 1 running, 196 sleeping, 0 stopped, 0 zombie
Cpu(s): 71.2%us, 4.7%sy, 0.0%ni, 24.1%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 3943228k total, 1689632k used, 2253596k free, 74960k buffers
Swap: 4087804k total, 0k used, 4087804k free, 945336k cached
Tasks: 197 total, 1 running, 196 sleeping, 0 stopped, 0 zombie
Cpu(s): 71.2%us, 4.7%sy, 0.0%ni, 24.1%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 3943228k total, 1689632k used, 2253596k free, 74960k buffers
Swap: 4087804k total, 0k used, 4087804k free, 945336k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
3352 jacob 20 0 262m 644 428 S 286 0.0 0:17.16 spin
3341 root -51 0 0 0 0 D 25 0.0 0:01.62 kidle_inject/0
3344 root -51 0 0 0 0 D 25 0.0 0:01.60 kidle_inject/3
3342 root -51 0 0 0 0 D 25 0.0 0:01.61 kidle_inject/1
3343 root -51 0 0 0 0 D 25 0.0 0:01.60 kidle_inject/2
2935 jacob 20 0 696m 125m 35m S 5 3.3 0:31.11 firefox
1546 root 20 0 158m 20m 6640 S 3 0.5 0:26.97 Xorg
2100 jacob 20 0 1223m 88m 30m S 3 2.3 0:23.68 compiz
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
3352 jacob 20 0 262m 644 428 S 286 0.0 0:17.16 spin
3341 root -51 0 0 0 0 D 25 0.0 0:01.62 kidle_inject/0
3344 root -51 0 0 0 0 D 25 0.0 0:01.60 kidle_inject/3
3342 root -51 0 0 0 0 D 25 0.0 0:01.61 kidle_inject/1
3343 root -51 0 0 0 0 D 25 0.0 0:01.60 kidle_inject/2
2935 jacob 20 0 696m 125m 35m S 5 3.3 0:31.11 firefox
1546 root 20 0 158m 20m 6640 S 3 0.5 0:26.97 Xorg
2100 jacob 20 0 1223m 88m 30m S 3 2.3 0:23.68 compiz
Tests have shown that by using the powerclamp driver as a cooling
device, a PID based userspace thermal controller can manage to

54
Documentation/thermal/nouveau_thermal → Documentation/thermal/nouveau_thermal.rst
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@ -1,13 +1,15 @@
=====================
Kernel driver nouveau
===================
=====================
Supported chips:
* NV43+
Authors: Martin Peres (mupuf) <martin.peres@free.fr>
Description
---------
-----------
This driver allows to read the GPU core temperature, drive the GPU fan and
set temperature alarms.
@ -19,20 +21,25 @@ interface is likely not to work. This document may then not cover your situation
entirely.
Temperature management
--------------------
----------------------
Temperature is exposed under as a read-only HWMON attribute temp1_input.
In order to protect the GPU from overheating, Nouveau supports 4 configurable
temperature thresholds:
* Fan_boost: Fan speed is set to 100% when reaching this temperature;
* Downclock: The GPU will be downclocked to reduce its power dissipation;
* Critical: The GPU is put on hold to further lower power dissipation;
* Shutdown: Shut the computer down to protect your GPU.
* Fan_boost:
Fan speed is set to 100% when reaching this temperature;
* Downclock:
The GPU will be downclocked to reduce its power dissipation;
* Critical:
The GPU is put on hold to further lower power dissipation;
* Shutdown:
Shut the computer down to protect your GPU.
WARNING: Some of these thresholds may not be used by Nouveau depending
on your chipset.
WARNING:
Some of these thresholds may not be used by Nouveau depending
on your chipset.
The default value for these thresholds comes from the GPU's vbios. These
thresholds can be configured thanks to the following HWMON attributes:
@ -46,19 +53,24 @@ NOTE: Remember that the values are stored as milli degrees Celsius. Don't forget
to multiply!
Fan management
------------
--------------
Not all cards have a drivable fan. If you do, then the following HWMON
attributes should be available:
* pwm1_enable: Current fan management mode (NONE, MANUAL or AUTO);
* pwm1: Current PWM value (power percentage);
* pwm1_min: The minimum PWM speed allowed;
* pwm1_max: The maximum PWM speed allowed (bypassed when hitting Fan_boost);
* pwm1_enable:
Current fan management mode (NONE, MANUAL or AUTO);
* pwm1:
Current PWM value (power percentage);
* pwm1_min:
The minimum PWM speed allowed;
* pwm1_max:
The maximum PWM speed allowed (bypassed when hitting Fan_boost);
You may also have the following attribute:
* fan1_input: Speed in RPM of your fan.
* fan1_input:
Speed in RPM of your fan.
Your fan can be driven in different modes:
@ -66,14 +78,16 @@ Your fan can be driven in different modes:
* 1: The fan can be driven in manual (use pwm1 to change the speed);
* 2; The fan is driven automatically depending on the temperature.
NOTE: Be sure to use the manual mode if you want to drive the fan speed manually
NOTE:
Be sure to use the manual mode if you want to drive the fan speed manually
NOTE2: When operating in manual mode outside the vbios-defined
[PWM_min, PWM_max] range, the reported fan speed (RPM) may not be accurate
depending on your hardware.
NOTE2:
When operating in manual mode outside the vbios-defined
[PWM_min, PWM_max] range, the reported fan speed (RPM) may not be accurate
depending on your hardware.
Bug reports
---------
-----------
Thermal management on Nouveau is new and may not work on all cards. If you have
inquiries, please ping mupuf on IRC (#nouveau, freenode).

142
Documentation/thermal/power_allocator.txt → Documentation/thermal/power_allocator.rst
View File

@ -1,3 +1,4 @@
=================================
Power allocator governor tunables
=================================
@ -25,36 +26,36 @@ temperature as the control input and power as the controlled output:
P_max = k_p * e + k_i * err_integral + k_d * diff_err + sustainable_power
where
e = desired_temperature - current_temperature
err_integral is the sum of previous errors
diff_err = e - previous_error
- e = desired_temperature - current_temperature
- err_integral is the sum of previous errors
- diff_err = e - previous_error
It is similar to the one depicted below:
It is similar to the one depicted below::
k_d
|
current_temp |
| v
| +----------+ +---+
| +----->| diff_err |-->| X |------+
| | +----------+ +---+ |
| | | tdp actor
| | k_i | | get_requested_power()
| | | | | | |
| | | | | | | ...
v | v v v v v
+---+ | +-------+ +---+ +---+ +---+ +----------+
| S |-------+----->| sum e |----->| X |--->| S |-->| S |-->|power |
+---+ | +-------+ +---+ +---+ +---+ |allocation|
^ | ^ +----------+
| | | | |
| | +---+ | | |
| +------->| X |-------------------+ v v
| +---+ granted performance
desired_temperature ^
|
|
k_po/k_pu
k_d
|
current_temp |
| v
| +----------+ +---+
| +----->| diff_err |-->| X |------+
| | +----------+ +---+ |
| | | tdp actor
| | k_i | | get_requested_power()
| | | | | | |
| | | | | | | ...
v | v v v v v
+---+ | +-------+ +---+ +---+ +---+ +----------+
| S |-----+----->| sum e |----->| X |--->| S |-->| S |-->|power |
+---+ | +-------+ +---+ +---+ +---+ |allocation|
^ | ^ +----------+
| | | | |
| | +---+ | | |
| +------->| X |-------------------+ v v
| +---+ granted performance
desired_temperature ^
|
|
k_po/k_pu
Sustainable power
-----------------
@ -73,7 +74,7 @@ is typically 2000mW, while on a 10" tablet is around 4500mW (may vary
depending on screen size).
If you are using device tree, do add it as a property of the
thermal-zone. For example:
thermal-zone. For example::
thermal-zones {
soc_thermal {
@ -85,7 +86,7 @@ thermal-zone. For example:
Instead, if the thermal zone is registered from the platform code, pass a
`thermal_zone_params` that has a `sustainable_power`. If no
`thermal_zone_params` were being passed, then something like below
will suffice:
will suffice::
static const struct thermal_zone_params tz_params = {
.sustainable_power = 3500,
@ -112,18 +113,18 @@ available capacity at a low temperature. On the other hand, a high
value of `k_pu` will result in the governor granting very high power
while temperature is low, and may lead to temperature overshooting.
The default value for `k_pu` is:
The default value for `k_pu` is::
2 * sustainable_power / (desired_temperature - switch_on_temp)
This means that at `switch_on_temp` the output of the controller's
proportional term will be 2 * `sustainable_power`. The default value
for `k_po` is:
for `k_po` is::
sustainable_power / (desired_temperature - switch_on_temp)
Focusing on the proportional and feed forward values of the PID
controller equation we have:
controller equation we have::
P_max = k_p * e + sustainable_power
@ -134,21 +135,23 @@ is the desired one, then the proportional component is zero and
thermal equilibrium under constant load. `sustainable_power` is only
an estimate, which is the reason for closed-loop control such as this.
Expanding `k_pu` we get:
P_max = 2 * sustainable_power * (T_set - T) / (T_set - T_on) +
sustainable_power
Expanding `k_pu` we get::
where
T_set is the desired temperature
T is the current temperature
T_on is the switch on temperature
P_max = 2 * sustainable_power * (T_set - T) / (T_set - T_on) +
sustainable_power
where:
- T_set is the desired temperature
- T is the current temperature
- T_on is the switch on temperature
When the current temperature is the switch_on temperature, the above
formula becomes:
formula becomes::
P_max = 2 * sustainable_power * (T_set - T_on) / (T_set - T_on) +
sustainable_power = 2 * sustainable_power + sustainable_power =
3 * sustainable_power
sustainable_power = 2 * sustainable_power + sustainable_power =
3 * sustainable_power
Therefore, the proportional term alone linearly decreases power from
3 * `sustainable_power` to `sustainable_power` as the temperature
@ -178,11 +181,18 @@ Cooling device power API
Cooling devices controlled by this governor must supply the additional
"power" API in their `cooling_device_ops`. It consists on three ops:
1. int get_requested_power(struct thermal_cooling_device *cdev,
struct thermal_zone_device *tz, u32 *power);
@cdev: The `struct thermal_cooling_device` pointer
@tz: thermal zone in which we are currently operating
@power: pointer in which to store the calculated power
1. ::
int get_requested_power(struct thermal_cooling_device *cdev,
struct thermal_zone_device *tz, u32 *power);
@cdev:
The `struct thermal_cooling_device` pointer
@tz:
thermal zone in which we are currently operating
@power:
pointer in which to store the calculated power
`get_requested_power()` calculates the power requested by the device
in milliwatts and stores it in @power . It should return 0 on
@ -190,23 +200,37 @@ success, -E* on failure. This is currently used by the power
allocator governor to calculate how much power to give to each cooling
device.
2. int state2power(struct thermal_cooling_device *cdev, struct
thermal_zone_device *tz, unsigned long state, u32 *power);
@cdev: The `struct thermal_cooling_device` pointer
@tz: thermal zone in which we are currently operating
@state: A cooling device state
@power: pointer in which to store the equivalent power
2. ::
int state2power(struct thermal_cooling_device *cdev, struct
thermal_zone_device *tz, unsigned long state,
u32 *power);
@cdev:
The `struct thermal_cooling_device` pointer
@tz:
thermal zone in which we are currently operating
@state:
A cooling device state
@power:
pointer in which to store the equivalent power
Convert cooling device state @state into power consumption in
milliwatts and store it in @power. It should return 0 on success, -E*
on failure. This is currently used by thermal core to calculate the
maximum power that an actor can consume.
3. int power2state(struct thermal_cooling_device *cdev, u32 power,
unsigned long *state);
@cdev: The `struct thermal_cooling_device` pointer
@power: power in milliwatts
@state: pointer in which to store the resulting state
3. ::
int power2state(struct thermal_cooling_device *cdev, u32 power,
unsigned long *state);
@cdev:
The `struct thermal_cooling_device` pointer
@power:
power in milliwatts
@state:
pointer in which to store the resulting state
Calculate a cooling device state that would make the device consume at
most @power mW and store it in @state. It should return 0 on success,

500
Documentation/thermal/sysfs-api.txt → Documentation/thermal/sysfs-api.rst
View File

@ -1,3 +1,4 @@
===================================
Generic Thermal Sysfs driver How To
===================================
@ -9,6 +10,7 @@ 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
@ -25,59 +27,90 @@ 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
- `[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 *type,
int trips, int mask, void *devdata,
struct thermal_zone_device_ops *ops,
const struct thermal_zone_params *tzp,
int passive_delay, int polling_delay))
---------------------------------
::
struct thermal_zone_device
*thermal_zone_device_register(char *type,
int trips, int mask, void *devdata,
struct thermal_zone_device_ops *ops,
const struct thermal_zone_params *tzp,
int passive_delay, int polling_delay))
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
/sys/class/thermal folder as `thermal_zone[0-*]`. It tries to bind all the
thermal cooling devices registered at the same time.
type: the thermal zone type.
trips: the total number of trip points this thermal zone supports.
mask: Bit string: If 'n'th bit is set, then trip point 'n' is writeable.
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.
.set_trips: set the trip points window. Whenever the current temperature
type:
the thermal zone type.
trips:
the total number of trip points this thermal zone supports.
mask:
Bit string: If 'n'th bit is set, then trip point 'n' is writeable.
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.
.set_trips:
set the trip points window. Whenever the current temperature
is updated, the trip points immediately below and above the
current temperature are found.
.get_mode: get the current mode (enabled/disabled) of the thermal zone.
- "enabled" means the kernel thermal management is enabled.
- "disabled" will prevent kernel thermal driver action upon trip points
so that user applications can take charge of thermal management.
.set_mode: set the mode (enabled/disabled) 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
.get_mode:
get the current mode (enabled/disabled) of the thermal zone.
- "enabled" means the kernel thermal management is
enabled.
- "disabled" will prevent kernel thermal driver action
upon trip points so that user applications can take
charge of thermal management.
.set_mode:
set the mode (enabled/disabled) 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.
.set_emul_temp: set the emulation temperature which helps in debugging
.set_emul_temp:
set the emulation temperature which helps in debugging
different threshold temperature points.
tzp: thermal zone platform parameters.
passive_delay: number of milliseconds to wait between polls when
tzp:
thermal zone platform parameters.
passive_delay:
number of milliseconds to wait between polls when
performing passive cooling.
polling_delay: number of milliseconds to wait between polls when checking
polling_delay:
number of milliseconds to wait between polls when checking
whether trip points have been crossed (0 for interrupt driven systems).
::
1.1.2 void thermal_zone_device_unregister(struct thermal_zone_device *tz)
void thermal_zone_device_unregister(struct thermal_zone_device *tz)
This interface function removes the thermal zone device.
It deletes the corresponding entry from /sys/class/thermal folder and
unbinds all the thermal cooling devices it uses.
1.1.3 struct thermal_zone_device *thermal_zone_of_sensor_register(
struct device *dev, int sensor_id, void *data,
const struct thermal_zone_of_device_ops *ops)
::
struct thermal_zone_device
*thermal_zone_of_sensor_register(struct device *dev, int sensor_id,
void *data,
const struct thermal_zone_of_device_ops *ops)
This interface adds a new sensor to a DT thermal zone.
This function will search the list of thermal zones described in
@ -87,25 +120,33 @@ temperature) and throttle appropriate devices.
thermal zone device.
The parameters for this interface are:
dev: Device node of sensor containing valid node pointer in
dev->of_node.
sensor_id: a sensor identifier, in case the sensor IP has more
than one sensors
data: a private pointer (owned by the caller) that will be
passed back, when a temperature reading is needed.
ops: struct thermal_zone_of_device_ops *.
get_temp: a pointer to a function that reads the
dev:
Device node of sensor containing valid node pointer in
dev->of_node.
sensor_id:
a sensor identifier, in case the sensor IP has more
than one sensors
data:
a private pointer (owned by the caller) that will be
passed back, when a temperature reading is needed.
ops:
`struct thermal_zone_of_device_ops *`.
============== =======================================
get_temp a pointer to a function that reads the
sensor temperature. This is mandatory
callback provided by sensor driver.
set_trips: a pointer to a function that sets a
set_trips a pointer to a function that sets a
temperature window. When this window is
left the driver must inform the thermal
core via thermal_zone_device_update.
get_trend: a pointer to a function that reads the
get_trend a pointer to a function that reads the
sensor temperature trend.
set_emul_temp: a pointer to a function that sets
set_emul_temp a pointer to a function that sets
sensor emulated temperature.
============== =======================================
The thermal zone temperature is provided by the get_temp() function
pointer of thermal_zone_of_device_ops. When called, it will
have the private pointer @data back.
@ -114,8 +155,10 @@ temperature) and throttle appropriate devices.
handle. Caller should check the return handle with IS_ERR() for finding
whether success or not.
1.1.4 void thermal_zone_of_sensor_unregister(struct device *dev,
struct thermal_zone_device *tzd)
::
void thermal_zone_of_sensor_unregister(struct device *dev,
struct thermal_zone_device *tzd)
This interface unregisters a sensor from a DT thermal zone which was
successfully added by interface thermal_zone_of_sensor_register().
@ -124,21 +167,29 @@ temperature) and throttle appropriate devices.
interface. It will also silent the zone by remove the .get_temp() and
get_trend() thermal zone device callbacks.
1.1.5 struct thermal_zone_device *devm_thermal_zone_of_sensor_register(
struct device *dev, int sensor_id,
void *data, const struct thermal_zone_of_device_ops *ops)
::
struct thermal_zone_device
*devm_thermal_zone_of_sensor_register(struct device *dev,
int sensor_id,
void *data,
const struct thermal_zone_of_device_ops *ops)
This interface is resource managed version of
thermal_zone_of_sensor_register().
All details of thermal_zone_of_sensor_register() described in
section 1.1.3 is applicable here.
The benefit of using this interface to register sensor is that it
is not require to explicitly call thermal_zone_of_sensor_unregister()
in error path or during driver unbinding as this is done by driver
resource manager.
1.1.6 void devm_thermal_zone_of_sensor_unregister(struct device *dev,
struct thermal_zone_device *tzd)
::
void devm_thermal_zone_of_sensor_unregister(struct device *dev,
struct thermal_zone_device *tzd)
This interface is resource managed version of
thermal_zone_of_sensor_unregister().
@ -147,123 +198,186 @@ temperature) and throttle appropriate devices.
Normally this function will not need to be called and the resource
management code will ensure that the resource is freed.
1.1.7 int thermal_zone_get_slope(struct thermal_zone_device *tz)
::
int thermal_zone_get_slope(struct thermal_zone_device *tz)
This interface is used to read the slope attribute value
for the thermal zone device, which might be useful for platform
drivers for temperature calculations.
1.1.8 int thermal_zone_get_offset(struct thermal_zone_device *tz)
::
int thermal_zone_get_offset(struct thermal_zone_device *tz)
This interface is used to read the offset attribute value
for the thermal zone device, which might be useful for platform
drivers for temperature calculations.
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 *)
------------------------------------
::
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 /sys/class/thermal/ folder as `cooling_device[0-*]`. It tries to bind itself
to all the thermal zone devices registered 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 Currently requested 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)
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 Currently requested throttle state of the
cooling device.
.set_cur_state:
set the Current throttle state of the cooling device.
::
void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev)
This interface function removes the thermal cooling device.
It deletes the corresponding entry from /sys/class/thermal folder and
unbinds 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,
unsigned long upper, unsigned long lower, unsigned int weight);
-----------------------------------------------------------------------------
::
int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz,
int trip, struct thermal_cooling_device *cdev,
unsigned long upper, unsigned long lower, unsigned int weight);
This interface function binds a thermal cooling device to a particular 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 in this thermal zone the cooling device
is associated with.
upper:the Maximum cooling state for this trip point.
THERMAL_NO_LIMIT means no upper limit,
and the cooling device can be in max_state.
lower:the Minimum cooling state can be used for this trip point.
THERMAL_NO_LIMIT means no lower limit,
and the cooling device can be in cooling state 0.
weight: the influence of this cooling device in this thermal
zone. See 1.4.1 below for more information.
1.3.2 int thermal_zone_unbind_cooling_device(struct thermal_zone_device *tz,
int trip, struct thermal_cooling_device *cdev);
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 in this thermal zone the cooling device
is associated with.
upper:
the Maximum cooling state for this trip point.
THERMAL_NO_LIMIT means no upper limit,
and the cooling device can be in max_state.
lower:
the Minimum cooling state can be used for this trip point.
THERMAL_NO_LIMIT means no lower limit,
and the cooling device can be in cooling state 0.
weight:
the influence of this cooling device in this thermal
zone. See 1.4.1 below for more information.
::
int thermal_zone_unbind_cooling_device(struct thermal_zone_device *tz,
int trip, struct thermal_cooling_device *cdev);
This interface function unbinds a thermal cooling device from a particular
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 in this thermal zone the cooling device
is associated with.
tz:
the thermal zone device
cdev:
thermal cooling device
trip:
indicates which trip point in this thermal zone the cooling device
is associated with.
1.4 Thermal Zone Parameters
1.4.1 struct thermal_bind_params
---------------------------
::
struct thermal_bind_params
This structure defines the following parameters that are used to bind
a zone with a cooling device for a particular trip point.
.cdev: The cooling device pointer
.weight: The 'influence' of a particular cooling device on this
zone. This is relative to the rest of the cooling
devices. For example, if all cooling devices have a
weight of 1, then they all contribute the same. You can
use percentages if you want, but it's not mandatory. A
weight of 0 means that this cooling device doesn't
contribute to the cooling of this zone unless all cooling
devices have a weight of 0. If all weights are 0, then
they all contribute the same.
.trip_mask:This is a bit mask that gives the binding relation between
this thermal zone and cdev, for a particular trip point.
If nth bit is set, then the cdev and thermal zone are bound
for trip point n.
.binding_limits: This is an array of cooling state limits. Must have
exactly 2 * thermal_zone.number_of_trip_points. It is an
array consisting of tuples <lower-state upper-state> of
state limits. Each trip will be associated with one state
limit tuple when binding. A NULL pointer means
<THERMAL_NO_LIMITS THERMAL_NO_LIMITS> on all trips.
These limits are used when binding a cdev to a trip point.
.match: This call back returns success(0) if the 'tz and cdev' need to
.cdev:
The cooling device pointer
.weight:
The 'influence' of a particular cooling device on this
zone. This is relative to the rest of the cooling
devices. For example, if all cooling devices have a
weight of 1, then they all contribute the same. You can
use percentages if you want, but it's not mandatory. A
weight of 0 means that this cooling device doesn't
contribute to the cooling of this zone unless all cooling
devices have a weight of 0. If all weights are 0, then
they all contribute the same.
.trip_mask:
This is a bit mask that gives the binding relation between
this thermal zone and cdev, for a particular trip point.
If nth bit is set, then the cdev and thermal zone are bound
for trip point n.
.binding_limits:
This is an array of cooling state limits. Must have
exactly 2 * thermal_zone.number_of_trip_points. It is an
array consisting of tuples <lower-state upper-state> of
state limits. Each trip will be associated with one state
limit tuple when binding. A NULL pointer means
<THERMAL_NO_LIMITS THERMAL_NO_LIMITS> on all trips.
These limits are used when binding a cdev to a trip point.
.match:
This call back returns success(0) if the 'tz and cdev' need to
be bound, as per platform data.
1.4.2 struct thermal_zone_params
::
struct thermal_zone_params
This structure defines the platform level parameters for a thermal zone.
This data, for each thermal zone should come from the platform layer.
This is an optional feature where some platforms can choose not to
provide this data.
.governor_name: Name of the thermal governor used for this zone
.no_hwmon: a boolean to indicate if the thermal to hwmon sysfs interface
is required. when no_hwmon == false, a hwmon sysfs interface
will be created. when no_hwmon == true, nothing will be done.
In case the thermal_zone_params is NULL, the hwmon interface
will be created (for backward compatibility).
.num_tbps: Number of thermal_bind_params entries for this zone
.tbp: thermal_bind_params entries
.governor_name:
Name of the thermal governor used for this zone
.no_hwmon:
a boolean to indicate if the thermal to hwmon sysfs interface
is required. when no_hwmon == false, a hwmon sysfs interface
will be created. when no_hwmon == true, nothing will be done.
In case the thermal_zone_params is NULL, the hwmon interface
will be created (for backward compatibility).
.num_tbps:
Number of thermal_bind_params entries for this zone
.tbp:
thermal_bind_params entries
2. sysfs attributes structure
=============================
== ================
RO read only value
WO write 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-*]:
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
@ -282,8 +396,9 @@ Thermal zone device sys I/F, created once it's registered:
|---slope: Slope constant applied as linear extrapolation
|---offset: Offset constant applied as linear extrapolation
Thermal cooling device sys I/F, created once it's registered:
/sys/class/thermal/cooling_device[0-*]:
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
@ -299,11 +414,13 @@ the relationship between a thermal zone and its associated cooling device.
They are created/removed for each successful execution of
thermal_zone_bind_cooling_device/thermal_zone_unbind_cooling_device.
/sys/class/thermal/thermal_zone[0-*]:
::
/sys/class/thermal/thermal_zone[0-*]:
|---cdev[0-*]: [0-*]th cooling device in current thermal zone
|---cdev[0-*]_trip_point: Trip point that cdev[0-*] is associated with
|---cdev[0-*]_weight: Influence of the cooling device in
this thermal zone
this thermal zone
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_
@ -311,16 +428,17 @@ 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-*]:
::
/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.rst for additional information.
***************************
* Thermal zone attributes *
***************************
Thermal zone attributes
-----------------------
type
Strings which represent the thermal zone type.
@ -340,54 +458,67 @@ mode
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
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
`trip_point_[0-*]_temp`
The temperature above which trip point will be fired.
Unit: millidegree Celsius
RO, Optional
trip_point_[0-*]_type
`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
E.g. it can be one of critical, hot, passive, `active[0-*]` for ACPI
thermal zone.
RO, Optional
trip_point_[0-*]_hyst
`trip_point_[0-*]_hyst`
The hysteresis value for a trip point, represented as an integer
Unit: Celsius
RW, Optional
cdev[0-*]
`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
`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
`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
passive
Attribute is only present for zones in which the passive cooling
@ -395,8 +526,11 @@ passive
and can be set to a temperature (in millidegrees) to enable a
passive trip point for the zone. Activation is done by polling with
an interval of 1 second.
Unit: millidegrees Celsius
Valid values: 0 (disabled) or greater than 1000
RW, Optional
emul_temp
@ -407,17 +541,21 @@ emul_temp
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.
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/thermal/power_allocator.txt
more information see Documentation/thermal/power_allocator.rst
Unit: milliwatts
RW, Optional
k_po
@ -425,7 +563,8 @@ k_po
controller during temperature overshoot. Temperature overshoot
is when the current temperature is above the "desired
temperature" trip point. For more information see
Documentation/thermal/power_allocator.txt
Documentation/thermal/power_allocator.rst
RW, Optional
k_pu
@ -433,20 +572,23 @@ k_pu
controller during temperature undershoot. Temperature undershoot
is when the current temperature is below the "desired
temperature" trip point. For more information see
Documentation/thermal/power_allocator.txt
Documentation/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/thermal/power_allocator.txt
Documentation/thermal/power_allocator.rst
RW, Optional
k_d
The derivative term of the power allocator governor's PID
controller. For more information see
Documentation/thermal/power_allocator.txt
Documentation/thermal/power_allocator.rst
RW, Optional
integral_cutoff
@ -456,8 +598,10 @@ integral_cutoff
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/thermal/power_allocator.txt
Documentation/thermal/power_allocator.rst
Unit: millidegree Celsius
RW, Optional
slope
@ -465,6 +609,7 @@ slope
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
@ -472,28 +617,33 @@ offset
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 *
*****************************
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
@ -508,9 +658,11 @@ stats/time_in_state_ms:
units here is 10mS (similar to other time exported in /proc).
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:
@ -522,6 +674,7 @@ stats/trans_table:
RO, 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,
@ -532,11 +685,10 @@ thermal_cooling_device. Both are considered to have the same
effectiveness in cooling the thermal zone.
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:
method, the sys I/F structure will be built like this::
/sys/class/thermal:
|thermal_zone1:
/sys/class/thermal:
|thermal_zone1:
|---type: acpitz
|---temp: 37000
|---mode: enabled
@ -557,24 +709,24 @@ method, the sys I/F structure will be built like this:
|---cdev1_trip_point: 2 /* cdev1 can be used for active[0]*/
|---cdev1_weight: 1024
|cooling_device0:
|cooling_device0:
|---type: Processor
|---max_state: 8
|---cur_state: 0
|cooling_device3:
|cooling_device3:
|---type: Fan
|---max_state: 2
|---cur_state: 0
/sys/class/hwmon:
|hwmon0:
/sys/class/hwmon:
|hwmon0:
|---name: acpitz
|---temp1_input: 37000
|---temp1_crit: 100000
4. Event Notification
=====================
The framework includes a simple notification mechanism, in the form of a
netlink event. Netlink socket initialization is done during the _init_
@ -587,21 +739,28 @@ event will be one of:{THERMAL_AUX0, THERMAL_AUX1, THERMAL_CRITICAL,
THERMAL_DEV_FAULT}. Notification can be sent when the current temperature
crosses any of the configured thresholds.
5. Export Symbol APIs:
5. Export Symbol APIs
=====================
5.1. get_tz_trend
-----------------
5.1: get_tz_trend:
This function returns the trend of a thermal zone, i.e the rate of change
of temperature of the thermal zone. Ideally, the thermal sensor drivers
are supposed to implement the callback. If they don't, the thermal
framework calculated the trend by comparing the previous and the current
temperature values.
5.2:get_thermal_instance:
5.2. get_thermal_instance
-------------------------
This function returns the thermal_instance corresponding to a given
{thermal_zone, cooling_device, trip_point} combination. Returns NULL
if such an instance does not exist.
5.3:thermal_notify_framework:
5.3. thermal_notify_framework
-----------------------------
This function handles the trip events from sensor drivers. It starts
throttling the cooling devices according to the policy configured.
For CRITICAL and HOT trip points, this notifies the respective drivers,
@ -609,12 +768,15 @@ and does actual throttling for other trip points i.e ACTIVE and PASSIVE.
The throttling policy is based on the configured platform data; if no
platform data is provided, this uses the step_wise throttling policy.
5.4:thermal_cdev_update:
5.4. thermal_cdev_update
------------------------
This function serves as an arbitrator to set the state of a cooling
device. It sets the cooling device to the deepest cooling state if
possible.
6. thermal_emergency_poweroff:
6. thermal_emergency_poweroff
=============================
On an event of critical trip temperature crossing. Thermal framework
allows the system to shutdown gracefully by calling orderly_poweroff().

28
Documentation/thermal/x86_pkg_temperature_thermal → Documentation/thermal/x86_pkg_temperature_thermal.rst
View File

@ -1,19 +1,23 @@
===================================
Kernel driver: x86_pkg_temp_thermal
===================
===================================
Supported chips:
* x86: with package level thermal management
(Verify using: CPUID.06H:EAX[bit 6] =1)
Authors: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Reference
---
---------
Intel® 64 and IA-32 Architectures Software Developer’s Manual (Jan, 2013):
Chapter 14.6: PACKAGE LEVEL THERMAL MANAGEMENT
Description
---------
-----------
This driver register CPU digital temperature package level sensor as a thermal
zone with maximum two user mode configurable trip points. Number of trip points
@ -25,23 +29,27 @@ take any action to control temperature.
Threshold management
--------------------
Each package will register as a thermal zone under /sys/class/thermal.
Example:
/sys/class/thermal/thermal_zone1
Example::
/sys/class/thermal/thermal_zone1
This contains two trip points:
- trip_point_0_temp
- trip_point_1_temp
User can set any temperature between 0 to TJ-Max temperature. Temperature units
are in milli-degree Celsius. Refer to "Documentation/thermal/sysfs-api.txt" for
are in milli-degree Celsius. Refer to "Documentation/thermal/sysfs-api.rst" for
thermal sys-fs details.
Any value other than 0 in these trip points, can trigger thermal notifications.
Setting 0, stops sending thermal notifications.
Thermal notifications: To get kobject-uevent notifications, set the thermal zone
policy to "user_space". For example: echo -n "user_space" > policy
Thermal notifications:
To get kobject-uevent notifications, set the thermal zone
policy to "user_space".
For example::
echo -n "user_space" > policy

2
MAINTAINERS
View File

@ -15618,7 +15618,7 @@ M: Viresh Kumar <viresh.kumar@linaro.org>
M: Javi Merino <javi.merino@kernel.org>
L: linux-pm@vger.kernel.org
S: Supported
F: Documentation/thermal/cpu-cooling-api.txt
F: Documentation/thermal/cpu-cooling-api.rst
F: drivers/thermal/cpu_cooling.c
F: include/linux/cpu_cooling.h

4
include/linux/thermal.h
View File

@ -251,7 +251,7 @@ struct thermal_bind_params {
* platform characterization. This value is relative to the
* rest of the weights so a cooling device whose weight is
* double that of another cooling device is twice as
* effective. See Documentation/thermal/sysfs-api.txt for more
* effective. See Documentation/thermal/sysfs-api.rst for more
* information.
*/
int weight;
@ -259,7 +259,7 @@ struct thermal_bind_params {
/*
* This is a bit mask that gives the binding relation between this
* thermal zone and cdev, for a particular trip point.
* See Documentation/thermal/sysfs-api.txt for more information.
* See Documentation/thermal/sysfs-api.rst for more information.
*/
int trip_mask;