Re: [PATCH v1 8/9] dt-bindings: iio: afe: add binding for temperature-sense-current
From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
Date: 2021-06-01 16:47:26
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linux-iio, lkml
On Sat, 29 May 2021 20:59:16 -0400 Liam Beguin [off-list ref] wrote:
quoted hunk ↗ jump to hunk
From: Liam Beguin <redacted> An ADC is often used to measure other quantities indirectly. This binding describe one cases, the measurement of a temperature through a current sense amplifier (such as an AD590) and a sense resistor. Signed-off-by: Liam Beguin <redacted> --- .../iio/afe/temperature-sense-current.yaml | 61 +++++++++++++++++++ MAINTAINERS | 1 + 2 files changed, 62 insertions(+) create mode 100644 Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yamldiff --git a/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml b/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml new file mode 100644 index 000000000000..1bac74486102 --- /dev/null +++ b/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml@@ -0,0 +1,61 @@ +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/iio/afe/temperature-sense-current.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Temperature Sense Current + +maintainers: + - Liam Beguin <lvb@xiphos.com> + +description: | + When an io-channel measures the output voltage for a temperature current + sense amplifier such as the AD950, the interesting measurement is almost + always the corresponding temperature, not the voltage output. + This binding describes such a circuit. + +properties: + compatible: + const: temperature-sense-current
What about such a sensor connected to a current ADC? That was what I was immediately expecting when I saw the naming. You could daisy chain this with the current-sense-resistor AFE though that does seem overly messy. Anyhow this should be called something that reflects the presence of that sense resitor.
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+ + io-channels: + maxItems: 1 + description: | + Channel node of a voltage io-channel. + + '#io-channel-cells': + const: 1 + + sense-resistor-ohms: + description: The sense resistance. + + alpha-micro-amps-per-degree: + description: | + Linear output current gain of the temperature IC. + + use-kelvin-scale: + type: boolean + description: | + Boolean indicating if alpha uses Kelvin degrees instead of Celsius. + +additionalProperties: false +required: + - compatible + - io-channels + - sense-resistor-ohms + - alpha-micro-amps-per-degree + +examples: + - | + ad590: iio-rescale0 { + compatible = "temperature-sense-current"; + #io-channel-cells = <1>; + io-channels = <&temp_adc 2>; + + sense-resistor-ohms = <8060>; + use-kelvin-scale; + alpha-micro-amps-per-degree = <1>; + }; + +...diff --git a/MAINTAINERS b/MAINTAINERS index a7279af85adb..0eb7fcd94b66 100644 --- a/MAINTAINERS +++ b/MAINTAINERS@@ -8721,6 +8721,7 @@ L: linux-iio@vger.kernel.org S: Maintained F: Documentation/devicetree/bindings/iio/afe/current-sense-amplifier.yaml F: Documentation/devicetree/bindings/iio/afe/current-sense-shunt.yaml +F: Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml F: Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml F: Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml F: drivers/iio/afe/iio-rescale.c