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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham 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 4CC86FA372B for ; Wed, 16 Oct 2019 13:33:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 162E921D7A for ; Wed, 16 Oct 2019 13:33:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="kuJmsIwx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405388AbfJPNd6 (ORCPT ); Wed, 16 Oct 2019 09:33:58 -0400 Received: from mail-wm1-f67.google.com ([209.85.128.67]:53757 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405404AbfJPNd4 (ORCPT ); Wed, 16 Oct 2019 09:33:56 -0400 Received: by mail-wm1-f67.google.com with SMTP id i16so2953230wmd.3 for ; Wed, 16 Oct 2019 06:33:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:reply-to:from:date:message-id :subject:to:cc; bh=AYq2N2yEzQH1HjpxxmEeXqbt30IDy6qCih3rZuvrbBo=; b=kuJmsIwxhcDk12Qhi+jjnG3VISYs2cmQLedBqa44+pU9Q3QcxbB/q8/gGnQ3YT3+N4 JBcafTIvBkZtrvqVawGm0imvEn34920vkcFdC9bwedaJZe12oWjDOaxeDhMcRwqHU4B4 H1WWBqu0lVv+OQmSfXw7e1NrKGkK2n+wj1Tt+9pZjx8x6gRYGubtAmNsAZyGr6k/KFQI xrR15SLl6gJQTblye2208ucXr5jK0KW+gavggAAca5q8srF0zXJMTRkUBA7DvekxBDrM BxTTCfBk1oxab2unXDfQp9abC9BTgKNSQDMOUamBFovmmBhlqLf1WRImHptfBpjYUfuO gs2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:reply-to :from:date:message-id:subject:to:cc; bh=AYq2N2yEzQH1HjpxxmEeXqbt30IDy6qCih3rZuvrbBo=; b=hgJtr3mkn65PZmo96nujCFjPoEiPn/eMs8u6U+0f87uovWlRSYQN42Gv57z6CAr8lw bli8DsREuJa3+5kbLfZFiUB+WLlqqPd0jFbPj7oQZWjxjCnd/3yJ5tth0CYtstv+MJDq t/iPDfaJH9Bs+aVtq+C/16HS7IWJEXs5qLUfJoYCzRm3Ha5jbRaLMBgCFymozXxnkhJI LMUHSWCbiTvo362k60zs8wGyrkF6s3/MbAknLDES6BDDW8FojjFJIX1iIJYhOMrPAz1F RUb4rXxAIMgO1GgRyrT0R4cnl0TM45xQJgNPcFqPfzRMeNuf664W7cCO2MNAtMOWo07q lNBg== X-Gm-Message-State: APjAAAWUbt00GId01StTeM5j6sMdzwlkPKAd9ZUOF1u68BvvMghIlw/0 nDUh5hzXCoEoK4wQqXgXvhUzZvuYcZXhQiDf3bO0Rkmf X-Google-Smtp-Source: APXvYqy2AtTWdLiz35MFiNyM4ycc/XC9eWmml2Djpws8xt66XX+q0ikR7AIFMzbLfaZpRdlC3ltEFR1jEtBXJq7yFX0= X-Received: by 2002:a1c:2407:: with SMTP id k7mr3275299wmk.99.1571232834249; Wed, 16 Oct 2019 06:33:54 -0700 (PDT) MIME-Version: 1.0 References: <20190923121714.13672-1-andrea.merello@gmail.com> <20190923121714.13672-3-andrea.merello@gmail.com> <20191006085545.2df79667@archlinux> In-Reply-To: <20191006085545.2df79667@archlinux> Reply-To: andrea.merello@gmail.com From: Andrea Merello Date: Wed, 16 Oct 2019 15:33:42 +0200 Message-ID: Subject: Re: [PATCH 2/3] iio: max31856: add support for configuring the HW averaging To: Jonathan Cameron Cc: patrick.havelange@essensium.com, paresh.chaudhary@rockwellcollins.com, pmeerw@pmeerw.net, lars@metafoo.de, knaack.h@gmx.de, Matthew Weber , Colin King , linux-iio@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org Il giorno dom 6 ott 2019 alle ore 09:55 Jonathan Cameron ha scritto: > > On Mon, 23 Sep 2019 14:17:13 +0200 > Andrea Merello wrote: > > > This sensor can perform samples averaging in hardware, but currently the > > driver leaves this setting alone (default is no averaging). > > > > This patch introduces a new IIO attribute that allows the user to set the > > averaging as desired (the HW supports averaging of 2, 5, 8 or 16 samples) > > > > Signed-off-by: Andrea Merello > > Sounds like oversampling combined with a lower sampling frequency, so > there is standard ABI for that. OK. Do you refer to "oversampling_ratio"? The datasheet says this applies to thermocouple measure, but by doing some testing with real HW, it seems that this setting affects both thermocouple and cold-junction measures, so I guess it shouldn't be in the form "in_temp_raw_oversampling_ratio"; does this sound right to you? > Jonathan > > > --- > > drivers/iio/temperature/max31856.c | 43 ++++++++++++++++++++++++++++++ > > 1 file changed, 43 insertions(+) > > > > diff --git a/drivers/iio/temperature/max31856.c b/drivers/iio/temperature/max31856.c > > index d12613f7ba3c..8b2e0102fa5c 100644 > > --- a/drivers/iio/temperature/max31856.c > > +++ b/drivers/iio/temperature/max31856.c > > @@ -24,6 +24,8 @@ > > #define MAX31856_CR0_OCFAULT BIT(4) > > #define MAX31856_CR0_OCFAULT_MASK GENMASK(5, 4) > > #define MAX31856_CR0_FILTER_50HZ BIT(0) > > +#define MAX31856_AVERAGING_MASK GENMASK(6, 4) > > +#define MAX31856_AVERAGING_SHIFT 4 > > #define MAX31856_TC_TYPE_MASK GENMASK(3, 0) > > #define MAX31856_FAULT_OVUV BIT(1) > > #define MAX31856_FAULT_OPEN BIT(0) > > @@ -65,6 +67,7 @@ struct max31856_data { > > struct spi_device *spi; > > u32 thermocouple_type; > > bool filter_50hz; > > + int averaging; > > }; > > > > static int max31856_read(struct max31856_data *data, u8 reg, > > @@ -109,6 +112,10 @@ static int max31856_init(struct max31856_data *data) > > > > reg_cr1_val &= ~MAX31856_TC_TYPE_MASK; > > reg_cr1_val |= data->thermocouple_type; > > + > > + reg_cr1_val &= ~MAX31856_AVERAGING_MASK; > > + reg_cr1_val |= data->averaging << MAX31856_AVERAGING_SHIFT; > > + > > ret = max31856_write(data, MAX31856_CR1_REG, reg_cr1_val); > > if (ret) > > return ret; > > @@ -295,14 +302,50 @@ static ssize_t set_filter(struct device *dev, > > return len; > > } > > > > +static ssize_t show_averaging(struct device *dev, > > + struct device_attribute *attr, > > + char *buf) > > +{ > > + struct iio_dev *indio_dev = dev_to_iio_dev(dev); > > + struct max31856_data *data = iio_priv(indio_dev); > > + > > + return sprintf(buf, "%d\n", 1 << data->averaging); > > +} > > + > > +static ssize_t set_averaging(struct device *dev, > > + struct device_attribute *attr, > > + const char *buf, > > + size_t len) > > +{ > > + struct iio_dev *indio_dev = dev_to_iio_dev(dev); > > + struct max31856_data *data = iio_priv(indio_dev); > > + unsigned int nsamples; > > + int shift; > > + int ret; > > + > > + ret = kstrtouint(buf, 10, &nsamples); > > + if (ret) > > + return ret; > > + > > + shift = fls(nsamples) - 1; > > + if (nsamples > 16 || BIT(shift) != nsamples) > > + return -EINVAL; > > + > > + data->averaging = shift; > > + max31856_init(data); > > + return len; > > +} > > + > > static IIO_DEVICE_ATTR(fault_ovuv, 0444, show_fault_ovuv, NULL, 0); > > static IIO_DEVICE_ATTR(fault_oc, 0444, show_fault_oc, NULL, 0); > > static IIO_DEVICE_ATTR(filter, 0644, show_filter, set_filter, 0); > > +static IIO_DEVICE_ATTR(averaging, 0644, show_averaging, set_averaging, 0); > > > > static struct attribute *max31856_attributes[] = { > > &iio_dev_attr_fault_ovuv.dev_attr.attr, > > &iio_dev_attr_fault_oc.dev_attr.attr, > > &iio_dev_attr_filter.dev_attr.attr, > > + &iio_dev_attr_averaging.dev_attr.attr, > > NULL, > > }; > > >