xref: /kernel/linux/linux-6.6/Documentation/devicetree/bindings/thermal/generic-adc-thermal.yaml

# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
%YAML 1.2
---
$id: http://devicetree.org/schemas/thermal/generic-adc-thermal.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: General Purpose Analog To Digital Converter (ADC) based thermal sensor

maintainers:
  - Laxman Dewangan <ldewangan@nvidia.com>

description:
  On some of platforms, thermal sensor like thermistors are connected to
  one of ADC channel and sensor resistance is read via voltage across the
  sensor resistor. The voltage read across the sensor is mapped to
  temperature using voltage-temperature lookup table.

properties:
  compatible:
    const: generic-adc-thermal

  '#thermal-sensor-cells':
    const: 0

  io-channels:
    maxItems: 1

  io-channel-names:
    const: sensor-channel

  temperature-lookup-table:
    description: |
      Lookup table to map the relation between ADC value and temperature.
      When ADC is read, the value is looked up on the table to get the
      equivalent temperature.

      If not specified, driver assumes the ADC channel gives milliCelsius
      directly.
    $ref: /schemas/types.yaml#/definitions/int32-matrix
    items:
      items:
        - description: Temperature in milliCelsius
        - description: ADC read value

required:
  - compatible
  - '#thermal-sensor-cells'
  - io-channels
  - io-channel-names

additionalProperties: false

examples:
  - |
    #include <dt-bindings/thermal/thermal.h>

    thermal-sensor {
        compatible = "generic-adc-thermal";
        #thermal-sensor-cells = <0>;
        io-channels = <&ads1015 1>;
        io-channel-names = "sensor-channel";
        temperature-lookup-table = <
              (-40000) 2578
              (-39000) 2577
              (-38000) 2576
              (-37000) 2575
              (-36000) 2574
              (-35000) 2573
              (-34000) 2572
              (-33000) 2571
              (-32000) 2569
              (-31000) 2568
              (-30000) 2567
              /* skip */
              118000 254
              119000 247
              120000 240
              121000 233
              122000 226
              123000 220
              124000 214
              125000 208>;
    };
...