dt-bindings: thermal: Add yaml bindings for thermal zones (1202a442) · Commits · 戴 / test

Documentation/devicetree/bindings/thermal/thermal-zones.yaml

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		# SPDX-License-Identifier: (GPL-2.0)
		# Copyright 2020 Linaro Ltd.
		%YAML 1.2
		---
		$id: http://devicetree.org/schemas/thermal/thermal-zones.yaml#
		$schema: http://devicetree.org/meta-schemas/base.yaml#

		title: Thermal zone 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 overloads.

		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 thermal-zones.

		The polling-delay properties of a thermal-zone are bound to the maximum dT/dt
		(temperature derivative over time) in two situations for a thermal zone:
		1. when passive cooling is activated (polling-delay-passive)
		2. when the zone just needs to be monitored (polling-delay) or when
		active cooling is activated.

		The maximum dT/dt is highly bound to hardware power consumption and
		dissipation capability. The delays should be chosen to account for said
		max dT/dt, such that a device does not cross several trip boundaries
		unexpectedly between polls. Choosing the right polling delays shall avoid
		having the device in temperature ranges that may damage the silicon structures
		and reduce silicon lifetime.

		properties:
		$nodename:
		const: thermal-zones
		description:
		A /thermal-zones node is required in order to use the thermal framework to
		manage input from the various thermal zones in the system in order to
		mitigate thermal overload conditions. It does not represent a real device
		in the system, but acts as a container to link a thermal sensor device,
		platform-data regarding temperature thresholds and the mitigation actions
		to take when the temperature crosses those thresholds.

		patternProperties:
		"^[a-zA-Z][a-zA-Z0-9\\-]{1,12}-thermal$":
		type: object
		description:
		Each thermal zone node contains information about how frequently it
		must be checked, the sensor responsible for reporting temperature for
		this zone, one sub-node containing the various trip points for this
		zone and one sub-node containing all the zone cooling-maps.

		properties:
		polling-delay:
		$ref: /schemas/types.yaml#/definitions/uint32
		description:
		The maximum number of milliseconds to wait between polls when
		checking this thermal zone. Setting this to 0 disables the polling
		timers setup by the thermal framework and assumes that the thermal
		sensors in this zone support interrupts.

		polling-delay-passive:
		$ref: /schemas/types.yaml#/definitions/uint32
		description:
		The maximum number of milliseconds to wait between polls when
		checking this thermal zone while doing passive cooling. Setting
		this to 0 disables the polling timers setup by the thermal
		framework and assumes that the thermal sensors in this zone
		support interrupts.

		thermal-sensors:
		$ref: /schemas/types.yaml#/definitions/phandle-array
		maxItems: 1
		description:
		The thermal sensor phandle and sensor specifier used to monitor this
		thermal zone.

		coefficients:
		$ref: /schemas/types.yaml#/definitions/uint32-array
		description:
		An array of integers containing the coefficients of a linear equation
		that binds all the sensors listed in this thermal zone.

		The linear equation used is as follows,
		z = c0 * x0 + c1 * x1 + ... + c(n-1) * x(n-1) + cn
		where c0, c1, .., cn are the coefficients.

		Coefficients default to 1 in case this property is not specified. The
		coefficients are ordered and are matched with sensors by means of the
		sensor ID. Additional coefficients are interpreted as constant offset.

		sustainable-power:
		$ref: /schemas/types.yaml#/definitions/uint32
		description:
		An estimate of the sustainable power (in mW) that this thermal zone
		can dissipate at the desired control temperature. For reference, the
		sustainable power of a 4-inch phone is typically 2000mW, while on a
		10-inch tablet is around 4500mW.

		trips:
		type: object
		description:
		This node describes a set of points in the temperature domain at
		which the thermal framework needs to take action. The actions to
		be taken are defined in another node called cooling-maps.

		patternProperties:
		"^[a-zA-Z][a-zA-Z0-9\\-_]{0,63}$":
		type: object

		properties:
		temperature:
		$ref: /schemas/types.yaml#/definitions/int32
		minimum: -273000
		maximum: 200000
		description:
		An integer expressing the trip temperature in millicelsius.

		hysteresis:
		$ref: /schemas/types.yaml#/definitions/uint32
		description:
		An unsigned integer expressing the hysteresis delta with
		respect to the trip temperature property above, also in
		millicelsius. Any cooling action initiated by the framework is
		maintained until the temperature falls below
		(trip temperature - hysteresis). This potentially prevents a
		situation where the trip gets constantly triggered soon after
		cooling action is removed.

		type:
		$ref: /schemas/types.yaml#/definitions/string
		enum:
		- active # enable active cooling e.g. fans
		- passive # enable passive cooling e.g. throttling cpu
		- hot # send notification to driver
		- critical # send notification to driver, trigger shutdown
		description: \|
		There are four valid trip types: active, passive, hot,
		critical.

		The critical trip type is used to set the maximum
		temperature threshold above which the HW becomes
		unstable and underlying firmware might even trigger a
		reboot. Hitting the critical threshold triggers a system
		shutdown.

		The hot trip type can be used to send a notification to
		the thermal driver (if a .notify callback is registered).
		The action to be taken is left to the driver.

		The passive trip type can be used to slow down HW e.g. run
		the CPU, GPU, bus at a lower frequency.

		The active trip type can be used to control other HW to
		help in cooling e.g. fans can be sped up or slowed down

		required:
		- temperature
		- hysteresis
		- type
		additionalProperties: false

		additionalProperties: false

		cooling-maps:
		type: object
		description:
		This node describes the action to be taken when a thermal zone
		crosses one of the temperature thresholds described in the trips
		node. The action takes the form of a mapping relation between a
		trip and the target cooling device state.

		patternProperties:
		"^map[-a-zA-Z0-9]*$":
		type: object

		properties:
		trip:
		$ref: /schemas/types.yaml#/definitions/phandle
		description:
		A phandle of a trip point node within this thermal zone.

		cooling-device:
		$ref: /schemas/types.yaml#/definitions/phandle-array
		description:
		A list of cooling device phandles along with the minimum
		and maximum cooling state specifiers for each cooling
		device. Using the THERMAL_NO_LIMIT (-1UL) constant in the
		cooling-device phandle limit specifier lets the framework
		use the minimum and maximum cooling state for that cooling
		device automatically.

		contribution:
		$ref: /schemas/types.yaml#/definitions/uint32
		minimum: 0
		maximum: 100
		description:
		The percentage contribution of the cooling devices at the
		specific trip temperature referenced in this map
		to this thermal zone

		required:
		- trip
		- cooling-device
		additionalProperties: false

		required:
		- polling-delay
		- polling-delay-passive
		- thermal-sensors
		- trips
		additionalProperties: false

		examples:
		- \|
		#include <dt-bindings/interrupt-controller/arm-gic.h>
		#include <dt-bindings/thermal/thermal.h>

		// Example 1: SDM845 TSENS
		soc: soc@0 {
		#address-cells = <2>;
		#size-cells = <2>;

		/* ... */

		tsens0: thermal-sensor@c263000 {
		compatible = "qcom,sdm845-tsens", "qcom,tsens-v2";
		reg = <0 0x0c263000 0 0x1ff>, /* TM */
		<0 0x0c222000 0 0x1ff>; /* SROT */
		#qcom,sensors = <13>;
		interrupts = <GIC_SPI 506 IRQ_TYPE_LEVEL_HIGH>,
		<GIC_SPI 508 IRQ_TYPE_LEVEL_HIGH>;
		interrupt-names = "uplow", "critical";
		#thermal-sensor-cells = <1>;
		};

		tsens1: thermal-sensor@c265000 {
		compatible = "qcom,sdm845-tsens", "qcom,tsens-v2";
		reg = <0 0x0c265000 0 0x1ff>, /* TM */
		<0 0x0c223000 0 0x1ff>; /* SROT */
		#qcom,sensors = <8>;
		interrupts = <GIC_SPI 507 IRQ_TYPE_LEVEL_HIGH>,
		<GIC_SPI 509 IRQ_TYPE_LEVEL_HIGH>;
		interrupt-names = "uplow", "critical";
		#thermal-sensor-cells = <1>;
		};
		};

		/* ... */

		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";
		};

		cpu0_alert1: trip-point1 {
		temperature = <95000>;
		hysteresis = <2000>;
		type = "passive";
		};

		cpu0_crit: cpu_crit {
		temperature = <110000>;
		hysteresis = <1000>;
		type = "critical";
		};
		};

		cooling-maps {
		map0 {
		trip = <&cpu0_alert0>;
		/* Corresponds to 1400MHz in OPP table */
		cooling-device = <&CPU0 3 3>, <&CPU1 3 3>,
		<&CPU2 3 3>, <&CPU3 3 3>;
		};

		map1 {
		trip = <&cpu0_alert1>;
		/* Corresponds to 1000MHz in OPP table */
		cooling-device = <&CPU0 5 5>, <&CPU1 5 5>,
		<&CPU2 5 5>, <&CPU3 5 5>;
		};
		};
		};

		/* ... */

		cluster0-thermal {
		polling-delay-passive = <250>;
		polling-delay = <1000>;

		thermal-sensors = <&tsens0 5>;

		trips {
		cluster0_alert0: trip-point0 {
		temperature = <90000>;
		hysteresis = <2000>;
		type = "hot";
		};
		cluster0_crit: cluster0_crit {
		temperature = <110000>;
		hysteresis = <2000>;
		type = "critical";
		};
		};
		};

		/* ... */

		gpu-top-thermal {
		polling-delay-passive = <250>;
		polling-delay = <1000>;

		thermal-sensors = <&tsens0 11>;

		trips {
		gpu1_alert0: trip-point0 {
		temperature = <90000>;
		hysteresis = <2000>;
		type = "hot";
		};
		};
		};
		};
		...

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