On Thu, Mar 05, 2020 at 06:26:42PM +0530, Amit Kucheria wrote: > As part of moving the thermal bindings to YAML, split it up into 3 > bindings: thermal sensors, cooling devices and thermal zones. > > The property #cooling-cells is required in each device that acts as a > cooling device - whether active or passive. So any device that can > throttle its performance to passively reduce heat dissipation (e.g. > cpus, gpus) and any device that can actively dissipate heat at different > levels (e.g. fans) will contain this property. > > Signed-off-by: Amit Kucheria <amit.kucheria@xxxxxxxxxx> > --- > .../thermal/thermal-cooling-devices.yaml | 114 ++++++++++++++++++ > 1 file changed, 114 insertions(+) > create mode 100644 Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml > > diff --git a/Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml b/Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml > new file mode 100644 > index 0000000000000..4745ea4b41ae7 > --- /dev/null > +++ b/Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml > @@ -0,0 +1,114 @@ > +# 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@xxxxxxxxxx> > + > +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 artively > + - 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. > + This and patch 1 should have a 'select: true' so that this schema is applied to all nodes (it does nothing if #cooling-cells is not present). > +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 > + > +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>; > + cooling-device = <&CPU0 THERMAL_NO_LIMIT > + THERMAL_NO_LIMIT>; > + }; > + }; > + }; > + > + /* ... */ > + }; > +... > -- > 2.20.1 >
