[RFC PATCH v5 0/3] Convert thermal bindings to yaml

[RFC PATCH v5 0/3] Convert thermal bindings to yaml

[Amit Kucheria]

Hi all,

Here is a series splitting up the thermal bindings into 3 separate bindings
in YAML, one each of the sensor, cooling-device and the thermal zones.
Since I was learning about YAML parsers while creating these bindings,
there are bound to be some issues.

I have to add that the bindings as they exist today, don't really follow
the "describe the hardware" model of devicetree. e.g. the entire
thermal-zone binding is a software abstraction to tie arbitrary,
board-specific trip points to cooling strategies. This doesn't fit well
into the model where the same SoC in two different form-factor devices e.g.
mobile and laptop, will have fairly different thermal profiles and might
benefit from different trip points and mitigation heuristics. I've started
some experiments with moving the thermal zone data to a board-specific
platform data that is used to initialise a "thermal zone driver".

In any case, if we ever move down that path, it'll probably end up being v2
of the binding, so this series is still relevant.

Please help review.

Regards,
Amit


Amit Kucheria (3):
  dt-bindings: thermal: Add yaml bindings for thermal sensors
  dt-bindings: thermal: Add yaml bindings for thermal cooling-devices
  dt-bindings: thermal: Add yaml bindings for thermal zones

 .../thermal/thermal-cooling-devices.yaml      | 114 +++++++
 .../bindings/thermal/thermal-sensor.yaml      |  70 ++++
 .../bindings/thermal/thermal-zones.yaml       | 302 ++++++++++++++++++
 3 files changed, 486 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml
 create mode 100644 Documentation/devicetree/bindings/thermal/thermal-sensor.yaml
 create mode 100644 Documentation/devicetree/bindings/thermal/thermal-zones.yaml

-- 
2.20.1

[RFC PATCH v5 1/3] dt-bindings: thermal: Add yaml bindings for thermal sensors

[Amit Kucheria]

As part of moving the thermal bindings to YAML, split it up into 3
bindings: thermal sensors, cooling devices and thermal zones.

The property #thermal-sensor-cells is required in each device that acts
as a thermal sensor. It is used to uniquely identify the instance of the
thermal sensor inside the system.

Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
---
 .../bindings/thermal/thermal-sensor.yaml      | 70 +++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/thermal/thermal-sensor.yaml

diff --git a/Documentation/devicetree/bindings/thermal/thermal-sensor.yaml b/Documentation/devicetree/bindings/thermal/thermal-sensor.yaml
new file mode 100644
index 000000000000..ac32f54f2f98
--- /dev/null
+++ b/Documentation/devicetree/bindings/thermal/thermal-sensor.yaml
@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: (GPL-2.0 OR MIT)
+# Copyright 2020 Linaro Ltd.
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/thermal/thermal-sensor.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Thermal sensor binding
+
+maintainers:
+  - Amit Kucheria <amitk@kernel.org>
+
+description: |
+  Thermal management is achieved in devicetree by describing the sensor hardware
+  and the software abstraction of 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 artively
+   - thermal-zones: a container of the following node types used to describe all
+     thermal data for the platform
+
+  This binding describes the thermal-sensor.
+
+  Thermal sensor devices provide temperature sensing capabilities on thermal
+  zones. Typical devices are I2C ADC converters and bandgaps. Thermal sensor
+  devices may control one or more internal sensors.
+
+properties:
+  "#thermal-sensor-cells":
+    description:
+      Used to uniquely identify a thermal sensor instance within an IC. Will be
+      0 on sensor nodes with only a single sensor and at least 1 on nodes
+      containing several internal sensors.
+    enum: [0, 1]
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.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>;
+                    interrupt-names = "uplow";
+                    #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>;
+                    interrupt-names = "uplow";
+                    #thermal-sensor-cells = <1>;
+            };
+    };
+...
-- 
2.20.1

[RFC PATCH v5 2/3] dt-bindings: thermal: Add yaml bindings for thermal cooling-devices

[Amit Kucheria]

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@linaro.org>
---
 .../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 000000000000..6aafca25af9b
--- /dev/null
+++ b/Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml
@@ -0,0 +1,114 @@
+# SPDX-License-Identifier: (GPL-2.0 OR MIT)
+# 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 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.
+
+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

[RFC PATCH v5 3/3] dt-bindings: thermal: Add yaml bindings for thermal zones

[Amit Kucheria]

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       | 302 ++++++++++++++++++
 1 file changed, 302 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..bc1ce8e41324
--- /dev/null
+++ b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
@@ -0,0 +1,302 @@
+# SPDX-License-Identifier: (GPL-2.0 OR MIT)
+# 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 artively
+   - 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:
+  thermal-zones:
+    type: object
+    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.
+
+    properties:
+      $nodename:
+        pattern: "^[a-zA-Z][a-zA-Z0-9,\\-]{1,12}-thermal$"
+        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
+            minimum: 0
+            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
+            minimum: 0
+            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
+                    description:
+                      An integer expressing the trip temperature in millicelsius.
+
+                  hysteresis:
+                    $ref: /schemas/types.yaml#/definitions/uint32
+                    description:
+                      An unsigned integer expressing the hysteresis delta with
+                      respect to the trip temperature property above, also in
+                      millicelsius.
+
+                  type:
+                    oneOf:
+                      - items:
+                        - enum:
+                            - active
+                            - passive
+                            - hot
+                            - critical
+                    description: |
+                      There are four valid trip types,
+                       - active   - enable active cooling e.g. fans
+                       - passive  - enable passive cooling e.g. throttling cpu
+                       - hot      - send notification to driver if .notify
+                                    callback registered
+                       - critical - send notification to driver if .notify
+                                    callback registered and trigger a shutdown
+
+                required:
+                  - temperature
+                  - hysteresis
+                  - type
+
+          cooling-maps:
+            type: object
+            description:
+              This node describes the action to be taken when a thermal zone
+              crosses one of the temperature thresholds described in the trips
+              node. The action takes the form of a mapping relation between a
+              trip and the target cooling device state.
+
+            patternProperties:
+              "^map[0-9][-a-zA-Z0-9]*$":
+                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
+
+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>;
+                    interrupt-names = "uplow";
+                    #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>;
+                    interrupt-names = "uplow";
+                    #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

Re: [RFC PATCH v5 0/3] Convert thermal bindings to yaml

[Amit Kucheria]

Sigh, typo on my part with the version of the series. Will resend with
corrections.

On Mon, Feb 24, 2020 at 12:50 PM Amit Kucheria <amit.kucheria@linaro.org> wrote:
>
> Hi all,
>
> Here is a series splitting up the thermal bindings into 3 separate bindings
> in YAML, one each of the sensor, cooling-device and the thermal zones.
> Since I was learning about YAML parsers while creating these bindings,
> there are bound to be some issues.
>
> I have to add that the bindings as they exist today, don't really follow
> the "describe the hardware" model of devicetree. e.g. the entire
> thermal-zone binding is a software abstraction to tie arbitrary,
> board-specific trip points to cooling strategies. This doesn't fit well
> into the model where the same SoC in two different form-factor devices e.g.
> mobile and laptop, will have fairly different thermal profiles and might
> benefit from different trip points and mitigation heuristics. I've started
> some experiments with moving the thermal zone data to a board-specific
> platform data that is used to initialise a "thermal zone driver".
>
> In any case, if we ever move down that path, it'll probably end up being v2
> of the binding, so this series is still relevant.
>
> Please help review.
>
> Regards,
> Amit
>
>
> Amit Kucheria (3):
>   dt-bindings: thermal: Add yaml bindings for thermal sensors
>   dt-bindings: thermal: Add yaml bindings for thermal cooling-devices
>   dt-bindings: thermal: Add yaml bindings for thermal zones
>
>  .../thermal/thermal-cooling-devices.yaml      | 114 +++++++
>  .../bindings/thermal/thermal-sensor.yaml      |  70 ++++
>  .../bindings/thermal/thermal-zones.yaml       | 302 ++++++++++++++++++
>  3 files changed, 486 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml
>  create mode 100644 Documentation/devicetree/bindings/thermal/thermal-sensor.yaml
>  create mode 100644 Documentation/devicetree/bindings/thermal/thermal-zones.yaml
>
> --
> 2.20.1
>