dt-bindings: thermal: qcom: add adc-thermal monitor bindings

Add bindings for thermal monitor, part of Qualcomm PMIC5 chips. It is a
close counterpart of VADC part of those PMICs.
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210205000118.493610-2-dmitry.baryshkov@linaro.org

Documentation/devicetree/bindings/thermal/qcom-spmi-adc-tm5.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/thermal/qcom-spmi-adc-tm5.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm's SPMI PMIC ADC Thermal Monitoring
+maintainers:
+  - Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
+
+properties:
+  compatible:
+    const: qcom,spmi-adc-tm5
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  "#thermal-sensor-cells":
+    const: 1
+    description:
+      Number of cells required to uniquely identify the thermal sensors. Since
+      we have multiple sensors this is set to 1
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+  qcom,avg-samples:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: Number of samples to be used for measurement.
+    enum:
+      - 1
+      - 2
+      - 4
+      - 8
+      - 16
+    default: 1
+
+  qcom,decimation:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: This parameter is used to decrease ADC sampling rate.
+            Quicker measurements can be made by reducing decimation ratio.
+    enum:
+      - 250
+      - 420
+      - 840
+    default: 840
+
+patternProperties:
+  "^([-a-z0-9]*)@[0-7]$":
+    type: object
+    description:
+      Represent one thermal sensor.
+
+    properties:
+      reg:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        description: Specify the sensor channel. There are 8 channels in PMIC5's ADC TM
+        minimum: 0
+        maximum: 7
+
+      io-channels:
+        description:
+          From common IIO binding. Used to pipe PMIC ADC channel to thermal monitor
+
+      qcom,ratiometric:
+        $ref: /schemas/types.yaml#/definitions/flag
+        description:
+          Channel calibration type.
+          If this property is specified VADC will use the VDD reference
+          (1.875V) and GND for channel calibration. If property is not found,
+          channel will be calibrated with 0V and 1.25V reference channels,
+          also known as absolute calibration.
+
+      qcom,hw-settle-time-us:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        description: Time between AMUX getting configured and the ADC starting conversion.
+        enum: [15, 100, 200, 300, 400, 500, 600, 700, 1000, 2000, 4000, 8000, 16000, 32000, 64000, 128000]
+
+      qcom,pre-scaling:
+        $ref: /schemas/types.yaml#/definitions/uint32-array
+        description: Used for scaling the channel input signal before the
+          signal is fed to VADC. The configuration for this node is to know the
+          pre-determined ratio and use it for post scaling. It is a pair of
+          integers, denoting the numerator and denominator of the fraction by
+          which input signal is multiplied. For example, <1 3> indicates the
+          signal is scaled down to 1/3 of its value before ADC measurement.  If
+          property is not found default value depending on chip will be used.
+        items:
+          - const: 1
+          - enum: [ 1, 3, 4, 6, 20, 8, 10 ]
+
+    required:
+      - reg
+      - io-channels
+
+    additionalProperties:
+      false
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - "#address-cells"
+  - "#size-cells"
+  - "#thermal-sensor-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/iio/qcom,spmi-vadc.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    spmi_bus {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        pm8150b_adc: adc@3100 {
+            reg = <0x3100>;
+            compatible = "qcom,spmi-adc5";
+            #address-cells = <1>;
+            #size-cells = <0>;
+            #io-channel-cells = <1>;
+
+            /* Other propreties are omitted */
+            conn-therm@4f {
+                reg = <ADC5_AMUX_THM3_100K_PU>;
+                qcom,ratiometric;
+                qcom,hw-settle-time = <200>;
+            };
+        };
+
+        pm8150b_adc_tm: adc-tm@3500 {
+            compatible = "qcom,spmi-adc-tm5";
+            reg = <0x3500>;
+            interrupts = <0x2 0x35 0x0 IRQ_TYPE_EDGE_RISING>;
+            #thermal-sensor-cells = <1>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            conn-therm@0 {
+                reg = <0>;
+                io-channels = <&pm8150b_adc ADC5_AMUX_THM3_100K_PU>;
+                qcom,ratiometric;
+                qcom,hw-settle-time-us = <200>;
+            };
+        };
+    };
+...