As part of moving the thermal bindings to YAML, split it up into 3 bindings: thermal sensors, cooling devices and thermal zones. The thermal-zone binding is a software abstraction to capture the properties of each zone - how often they should be checked, the temperature thresholds (trips) at which mitigation actions need to be taken and the level of mitigation needed at those thresholds. Signed-off-by: Amit Kucheria <amit.kucheria@xxxxxxxxxx> Reviewed-by: Rob Herring <robh@xxxxxxxxxx> --- Changes since v3: - Clarify example by using cooling state numbers and a comment - Restrict thermal-sensors to a single reference to reflect actual code where there is a one-to-one mapping between sensors and thermal zones - Add two optional properties that were missed in earlier submissions: coefficients and sustainable-power - Improve description of hysteresis and contribution properties .../bindings/thermal/thermal-zones.yaml | 341 ++++++++++++++++++ 1 file changed, 341 insertions(+) create mode 100644 Documentation/devicetree/bindings/thermal/thermal-zones.yaml diff --git a/Documentation/devicetree/bindings/thermal/thermal-zones.yaml b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml new file mode 100644 index 0000000000000..302170d79fe94 --- /dev/null +++ b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml @@ -0,0 +1,341 @@ +# 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@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 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 1400MHz 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"; + }; + }; + }; + }; +... -- 2.20.1
