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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,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 7D3AAC47093 for ; Tue, 1 Jun 2021 16:43:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 58A64613B6 for ; Tue, 1 Jun 2021 16:43:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234505AbhFAQpR (ORCPT ); Tue, 1 Jun 2021 12:45:17 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]:3127 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232490AbhFAQpP (ORCPT ); Tue, 1 Jun 2021 12:45:15 -0400 Received: from fraeml709-chm.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Fvd6F3rKXz6V03Q; Wed, 2 Jun 2021 00:34:29 +0800 (CST) Received: from lhreml710-chm.china.huawei.com (10.201.108.61) by fraeml709-chm.china.huawei.com (10.206.15.37) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 1 Jun 2021 18:43:32 +0200 Received: from localhost (10.52.121.71) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Tue, 1 Jun 2021 17:43:31 +0100 Date: Tue, 1 Jun 2021 17:43:25 +0100 From: Jonathan Cameron To: Liam Beguin CC: , , , , , , , Subject: Re: [PATCH v1 7/9] dt-bindings: iio: afe: add binding for temperature-sense-rtd Message-ID: <20210601174325.00000ca2@Huawei.com> In-Reply-To: <20210530005917.20953-8-liambeguin@gmail.com> References: <20210530005917.20953-1-liambeguin@gmail.com> <20210530005917.20953-8-liambeguin@gmail.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.52.121.71] X-ClientProxiedBy: lhreml738-chm.china.huawei.com (10.201.108.188) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 29 May 2021 20:59:15 -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 Just one nit pick inline. Hmm. these devices use some 'special' units for their coefficients. Ah well, guess we copy the industry standard. > --- > .../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 > + 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 > + > + 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. > + > + r-naught-ohms: > + description: | > + Resistance of the sensor at 0 degrees Celsius. > + Common values are 100 for PT100 and 1000 for PT1000. > + > +additionalProperties: false > +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>; > + }; > + Drop this blank line. Doesn't add anything ;) > +... > 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 >