119 lines
4.2 KiB
YAML
119 lines
4.2 KiB
YAML
# SPDX-License-Identifier: (GPL-2.0)
|
|
# Copyright 2020 Linaro Ltd.
|
|
%YAML 1.2
|
|
---
|
|
$id: http://devicetree.org/schemas/thermal/thermal-cooling-devices.yaml#
|
|
$schema: http://devicetree.org/meta-schemas/core.yaml#
|
|
|
|
title: Thermal cooling device binding
|
|
|
|
maintainers:
|
|
- Amit Kucheria <amitk@kernel.org>
|
|
|
|
description: |
|
|
Thermal management is achieved in devicetree by describing the sensor hardware
|
|
and the software abstraction of cooling devices and thermal zones required to
|
|
take appropriate action to mitigate thermal overload.
|
|
|
|
The following node types are used to completely describe a thermal management
|
|
system in devicetree:
|
|
- thermal-sensor: device that measures temperature, has SoC-specific bindings
|
|
- cooling-device: device used to dissipate heat either passively or actively
|
|
- thermal-zones: a container of the following node types used to describe all
|
|
thermal data for the platform
|
|
|
|
This binding describes the cooling devices.
|
|
|
|
There are essentially two ways to provide control on power dissipation:
|
|
- Passive cooling: by means of regulating device performance. A typical
|
|
passive cooling mechanism is a CPU that has dynamic voltage and frequency
|
|
scaling (DVFS), and uses lower frequencies as cooling states.
|
|
- Active cooling: by means of activating devices in order to remove the
|
|
dissipated heat, e.g. regulating fan speeds.
|
|
|
|
Any cooling device has a range of cooling states (i.e. different levels of
|
|
heat dissipation). They also have a way to determine the state of cooling in
|
|
which the device is. For example, a fan's cooling states correspond to the
|
|
different fan speeds possible. Cooling states are referred to by single
|
|
unsigned integers, where larger numbers mean greater heat dissipation. The
|
|
precise set of cooling states associated with a device should be defined in
|
|
a particular device's binding.
|
|
|
|
select: true
|
|
|
|
properties:
|
|
"#cooling-cells":
|
|
description:
|
|
Must be 2, in order to specify minimum and maximum cooling state used in
|
|
the cooling-maps reference. The first cell is the minimum cooling state
|
|
and the second cell is the maximum cooling state requested.
|
|
const: 2
|
|
|
|
additionalProperties: true
|
|
|
|
examples:
|
|
- |
|
|
#include <dt-bindings/interrupt-controller/arm-gic.h>
|
|
#include <dt-bindings/thermal/thermal.h>
|
|
|
|
// Example 1: Cpufreq cooling device on CPU0
|
|
cpus {
|
|
#address-cells = <2>;
|
|
#size-cells = <0>;
|
|
|
|
CPU0: cpu@0 {
|
|
device_type = "cpu";
|
|
compatible = "qcom,kryo385";
|
|
reg = <0x0 0x0>;
|
|
enable-method = "psci";
|
|
cpu-idle-states = <&LITTLE_CPU_SLEEP_0
|
|
&LITTLE_CPU_SLEEP_1
|
|
&CLUSTER_SLEEP_0>;
|
|
capacity-dmips-mhz = <607>;
|
|
dynamic-power-coefficient = <100>;
|
|
qcom,freq-domain = <&cpufreq_hw 0>;
|
|
#cooling-cells = <2>;
|
|
next-level-cache = <&L2_0>;
|
|
L2_0: l2-cache {
|
|
compatible = "cache";
|
|
next-level-cache = <&L3_0>;
|
|
L3_0: l3-cache {
|
|
compatible = "cache";
|
|
};
|
|
};
|
|
};
|
|
|
|
/* ... */
|
|
|
|
};
|
|
|
|
/* ... */
|
|
|
|
thermal-zones {
|
|
cpu0-thermal {
|
|
polling-delay-passive = <250>;
|
|
polling-delay = <1000>;
|
|
|
|
thermal-sensors = <&tsens0 1>;
|
|
|
|
trips {
|
|
cpu0_alert0: trip-point0 {
|
|
temperature = <90000>;
|
|
hysteresis = <2000>;
|
|
type = "passive";
|
|
};
|
|
};
|
|
|
|
cooling-maps {
|
|
map0 {
|
|
trip = <&cpu0_alert0>;
|
|
/* Corresponds to 1000MHz in OPP table */
|
|
cooling-device = <&CPU0 5 5>;
|
|
};
|
|
};
|
|
};
|
|
|
|
/* ... */
|
|
};
|
|
...
|