From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.5 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A49BBC4743D for ; Sat, 5 Jun 2021 14:56:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 85AD461287 for ; Sat, 5 Jun 2021 14:56:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229989AbhFEO6q (ORCPT ); Sat, 5 Jun 2021 10:58:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:46808 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229930AbhFEO6p (ORCPT ); Sat, 5 Jun 2021 10:58:45 -0400 Received: from jic23-huawei (cpc108967-cmbg20-2-0-cust86.5-4.cable.virginm.net [81.101.6.87]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4EFF9613AC; Sat, 5 Jun 2021 14:56:55 +0000 (UTC) Date: Sat, 5 Jun 2021 15:58:42 +0100 From: Jonathan Cameron To: Rob Herring Cc: Liam Beguin , peda@axentia.se, lars@metafoo.de, pmeerw@pmeerw.net, linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, devicetree@vger.kernel.org Subject: Re: [PATCH v1 7/9] dt-bindings: iio: afe: add binding for temperature-sense-rtd Message-ID: <20210605155842.036edd94@jic23-huawei> In-Reply-To: <20210604211702.GA3925041@robh.at.kernel.org> References: <20210530005917.20953-1-liambeguin@gmail.com> <20210530005917.20953-8-liambeguin@gmail.com> <20210604211702.GA3925041@robh.at.kernel.org> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 4 Jun 2021 16:17:02 -0500 Rob Herring wrote: > On Sat, May 29, 2021 at 08:59:15PM -0400, Liam Beguin wrote: > > From: Liam Beguin > > > > An ADC is often used to measure other quantities indirectly. This > > binding describe one cases, the measurement of a temperature through > > the voltage across an RTD resistor such as a PT1000. > > > > Signed-off-by: Liam Beguin > > --- > > .../iio/afe/temperature-sense-rtd.yaml | 65 +++++++++++++++++++ > > MAINTAINERS | 1 + > > 2 files changed, 66 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml > > > > diff --git a/Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml b/Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml > > new file mode 100644 > > index 000000000000..4798eda6e533 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml > > @@ -0,0 +1,65 @@ > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) > > +%YAML 1.2 > > +--- > > +$id: http://devicetree.org/schemas/iio/afe/temperature-sense-rtd.yaml# > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > + > > +title: Temperature Sense RTD > > + > > +maintainers: > > + - Liam Beguin > > + > > +description: | > > + When an io-channel measures the output voltage across an RTD such as a > > What's an RTD? Not defined anywhere here. > > > + PT1000, the interesting measurement is almost always the corresponding > > + temperature, not the voltage output. This binding describes such a circuit. > > + > > +properties: > > + compatible: > > + const: temperature-sense-rtd > > + > > + io-channels: > > + maxItems: 1 > > + description: | > > + Channel node of a voltage io-channel. > > + > > + '#io-channel-cells': > > + const: 1 > > Doesn't this belong in the provider? Potentially this could in turn also be a provider if wired up to iio-hwmon or similar. Certainly an option for a temperature sensor. > > > + > > + excitation-current-microamp: > > + description: The current fed through the RTD sensor. > > + > > + alpha-micro-ohms-per-ohm-celsius: > > + description: | > > + Linear approximation of the resistance versus temperature relationship > > + between 0 and 100 degrees Celsius. > > + > > + Pure platinum has an alpha of 3925. Industry standards such as IEC60751 > > + and ASTM E-1137 specify an alpha of 3850. > > Is there a max and min value? > > > + > > + r-naught-ohms: > > + description: | > > + Resistance of the sensor at 0 degrees Celsius. > > + Common values are 100 for PT100 and 1000 for PT1000. > > max or min? > > > + > > +additionalProperties: false > > blank line here. > > > +required: > > + - compatible > > + - io-channels > > + - excitation-current-microamp > > + - alpha-micro-ohms-per-ohm-celsius > > + - r-naught-ohms > > + > > +examples: > > + - | > > + pt1000_1: iio-rescale0 { > > + compatible = "temperature-sense-rtd"; > > + #io-channel-cells = <1>; > > + io-channels = <&temp_adc1 0>; > > + > > + excitation-current-microamp = <1000>; > > + alpha-micro-ohms-per-ohm-celsius = <3908>; > > + r-naught-ohms = <1000>; > > + }; > > + > > +... > > diff --git a/MAINTAINERS b/MAINTAINERS > > index d3ab0ccc34ab..a7279af85adb 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-rtd.yaml > > F: Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml > > F: drivers/iio/afe/iio-rescale.c > > > > -- > > 2.30.1.489.g328c10930387