cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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temperature-sense-rtd.yaml (2709B)

      1# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
      2%YAML 1.2
      3---
      4$id: http://devicetree.org/schemas/iio/afe/temperature-sense-rtd.yaml#
      5$schema: http://devicetree.org/meta-schemas/core.yaml#
      6
      7title: Temperature Sense RTD
      8
      9maintainers:
     10  - Liam Beguin <liambeguin@gmail.com>
     11
     12description: |
     13  RTDs (Resistance Temperature Detectors) are a kind of temperature sensors
     14  used to get a linear voltage to temperature reading within a give range
     15  (usually 0 to 100 degrees Celsius).
     16
     17  When an io-channel measures the output voltage across an RTD such as a
     18  PT1000, the interesting measurement is almost always the corresponding
     19  temperature, not the voltage output. This binding describes such a circuit.
     20
     21  The general transfer function here is (using SI units)
     22
     23    V = R(T) * iexc
     24    R(T) = r0 * (1 + alpha * T)
     25    T = 1 / (alpha * r0 * iexc) * (V - r0 * iexc)
     26
     27  The following circuit matches what's in the examples section.
     28
     29           5V0
     30          -----
     31            |
     32        +---+----+
     33        |  R 5k  |
     34        +---+----+
     35            |
     36            V 1mA
     37            |
     38            +---- Vout
     39            |
     40        +---+----+
     41        | PT1000 |
     42        +---+----+
     43            |
     44          -----
     45           GND
     46
     47properties:
     48  compatible:
     49    const: temperature-sense-rtd
     50
     51  io-channels:
     52    maxItems: 1
     53    description: |
     54      Channel node of a voltage io-channel.
     55
     56  '#io-channel-cells':
     57    const: 0
     58
     59  excitation-current-microamp:
     60    description: The current fed through the RTD sensor.
     61
     62  alpha-ppm-per-celsius:
     63    description: |
     64      alpha can also be expressed in micro-ohms per ohm Celsius. It's a linear
     65      approximation of the resistance versus temperature relationship
     66      between 0 and 100 degrees Celsius.
     67
     68      alpha = (R_100 - R_0) / (100 * R_0)
     69
     70      Where, R_100 is the resistance of the sensor at 100 degrees Celsius, and
     71      R_0 (or r-naught-ohms) is the resistance of the sensor at 0 degrees
     72      Celsius.
     73
     74      Pure platinum has an alpha of 3925. Industry standards such as IEC60751
     75      and ASTM E-1137 specify an alpha of 3850.
     76
     77  r-naught-ohms:
     78    description: |
     79      Resistance of the sensor at 0 degrees Celsius.
     80      Common values are 100 for PT100, 500 for PT500, and 1000 for PT1000
     81
     82additionalProperties: false
     83required:
     84  - compatible
     85  - io-channels
     86  - excitation-current-microamp
     87  - alpha-ppm-per-celsius
     88  - r-naught-ohms
     89
     90examples:
     91  - |
     92    pt1000_1: temperature-sensor0 {
     93        compatible = "temperature-sense-rtd";
     94        #io-channel-cells = <0>;
     95        io-channels = <&temp_adc1 0>;
     96
     97        excitation-current-microamp = <1000>; /* i = U/R = 5 / 5000 */
     98        alpha-ppm-per-celsius = <3908>;
     99        r-naught-ohms = <1000>;
    100    };
    101...