Re: [PATCH v2 3/3] dt-bindings: thermal: Add yaml bindings for thermal zones

[Amit Kucheria <amit.kucheria@linaro.org>]

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On Tue, Mar 24, 2020 at 2:46 AM Rob Herring <robh@kernel.org> wrote:
>
> On Mon, Mar 23, 2020 at 2:46 PM Amit Kucheria <amit.kucheria@linaro.org> wrote:
> >
> > Hi Rob,
> >
> > Thanks for the review.
> >
> > On Wed, Mar 11, 2020 at 8:19 PM Rob Herring <robh@kernel.org> wrote:
> > >
> > > On Thu, Mar 05, 2020 at 06:26:43PM +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 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.
>

[...]

>
> > > > +            /* ... */
> > > > +
> > > > +            gpu-thermal-top {
> > >
> > > This one is not going to match (which should cause an error).
> >
> > Good catch. Unfortunately, this isn't getting caught. Nor is the
> > 12-char limitation before -thermal in the thermal zone name. I can't
> > figure out why.
>
> That's because this schema has to be included by another schema which
> matches on a parent node containing 'thermal-zones'. If
> 'thermal-zones' can be at the root node, then you should rework this
> such that you have $nodename: {const: thermal-zones} as a top-level
> property.

I've done all the change requested in the review(see attached patch),
including moving to

properties:
   $nodename:
       const: thermal-zones

but that generates a bunch of errors similar to:

/home/amit/work/builds/build-aarch64/Documentation/devicetree/bindings/arm/zte.example.dt.yaml:
/: $nodename:0: 'thermal-zones' was expected
/home/amit/work/builds/build-aarch64/Documentation/devicetree/bindings/arm/psci.example.dt.yaml:
/: $nodename:0: 'thermal-zones' was expected
/home/amit/work/builds/build-aarch64/Documentation/devicetree/bindings/arm/sunxi.example.dt.yaml:
/: $nodename:0: 'thermal-zones' was expected
/home/amit/work/builds/build-aarch64/Documentation/devicetree/bindings/arm/sprd/sprd.example.dt.yaml:
/: $nodename:0: 'thermal-zones' was expected
/home/amit/work/builds/build-aarch64/Documentation/devicetree/bindings/arm/calxeda.example.dt.yaml:
/: $nodename:0: 'thermal-zones' was expected
/home/amit/work/builds/build-aarch64/Documentation/devicetree/bindings/arm/ti/ti,davinci.example.dt.yaml:
/: $nodename:0: 'thermal-zones' was expected
/home/amit/work/builds/build-aarch64/Documentation/devicetree/bindings/arm/spear.example.dt.yaml:
/: $nodename:0: 'thermal-zones' was expected
/home/amit/work/builds/build-aarch64/Documentation/devicetree/bindings/arm/ti/nspire.example.dt.yaml:
/: $nodename:0: 'thermal-zones' was expected

It seems like dtc is expecting every node to have a thermal-zones node?

Looking at other root nodes such as cpus.yaml, the main difference I
noticed was the absence of the "select: true" property. However, if I
remove that, we go back to the schema not being applied.

You mentioned that the thermal-zones schema needs to included by
another schema. What did you mean by that?

Regards,
Amit

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From 74dc9532a709259cfe89edf7d323b8a531c4c96d Mon Sep 17 00:00:00 2001
Message-Id: <74dc9532a709259cfe89edf7d323b8a531c4c96d.1585044912.git.amit.kucheria@linaro.org>
From: Amit Kucheria <amit.kucheria@linaro.org>
Date: Fri, 7 Feb 2020 00:32:26 +0530
Subject: [PATCH] dt-bindings: thermal: Add yaml bindings for thermal zones

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@linaro.org>
---
 .../bindings/thermal/thermal-zones.yaml       | 321 ++++++++++++++++++
 1 file changed, 321 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 000000000000..4840e69ab7ea
--- /dev/null
+++ b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
@@ -0,0 +1,321 @@
+# 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.
+
+select: true
+
+properties:
+  $nodename:
+    const: thermal-zones
+    description:
+      A /thermal-zones node is required in order to use the thermal framework to
+      manage input from the various thermal zones in the system in order to
+      mitigate thermal overload conditions. It does not represent a real device
+      in the system, but acts as a container to link thermal sensor devices,
+      platform-data regarding temperature thresholds and the mitigation actions
+      to take when the temperature crosses those thresholds.
+
+patternProperties:
+ "^[a-zA-Z][a-zA-Z0-9\\-]{1,12}-thermal$":
+   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:
+       $ref: /schemas/types.yaml#/definitions/phandle-array
+       description:
+         A list of thermal sensor phandles and sensor specifiers used to
+         monitor this thermal zone.
+
+     trips:
+       type: object
+       description:
+         This node describes a set of points in the temperature domain at
+         which the thermal framework needs to takes action. The actions to
+         be taken are defined in another node called cooling-maps.
+
+       patternProperties:
+         "^[a-zA-Z][a-zA-Z0-9\\-_]{0,63}$":
+           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.
+
+             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 contribution of the cooling devices at the trip
+                 temperature, both referenced in this map, to this thermal
+                 zone as a percentage.
+
+           required:
+             - trip
+             - cooling-device
+           additionalProperties: false
+
+       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>;
+                                    cooling-device = <&CPU0 THERMAL_NO_LIMIT
+                                                            THERMAL_NO_LIMIT>,
+                                                     <&CPU1 THERMAL_NO_LIMIT
+                                                            THERMAL_NO_LIMIT>,
+                                                     <&CPU2 THERMAL_NO_LIMIT
+                                                            THERMAL_NO_LIMIT>,
+                                                     <&CPU3 THERMAL_NO_LIMIT
+                                                            THERMAL_NO_LIMIT>;
+                            };
+
+                            map1 {
+                                    trip = <&cpu0_alert1>;
+                                    cooling-device = <&CPU0 THERMAL_NO_LIMIT
+                                                            THERMAL_NO_LIMIT>,
+                                                     <&CPU1 THERMAL_NO_LIMIT
+                                                            THERMAL_NO_LIMIT>,
+                                                     <&CPU2 THERMAL_NO_LIMIT
+                                                            THERMAL_NO_LIMIT>,
+                                                     <&CPU3 THERMAL_NO_LIMIT
+                                                            THERMAL_NO_LIMIT>;
+                            };
+                    };
+            };
+
+            /* ... */
+
+            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-thermal-top {
+                    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