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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 DDE4AC4360C for ; Sun, 6 Oct 2019 07:55:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B18A4214AF for ; Sun, 6 Oct 2019 07:55:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570348551; bh=cTgYkYNvEZUYhQCHpW90nyT6f6A7TtppG794I28rVTQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=XtwGOYn5sHpW4OOPGq2K7MtM3h9DIduSEvjnS+xeMEsgPdWSeYdSZNFMlpKbq5fTl 77v21yw6egHmULvyW2yj1ul4mL3nmr3QhmHYK4zQUDPMUOABwtmmDGMvOEbZ7RVKzP aVNmQjSgPhjkkSG0bcAirc6FMHDeEDwfCWHkqlVI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726257AbfJFHzv (ORCPT ); Sun, 6 Oct 2019 03:55:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:40606 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726207AbfJFHzv (ORCPT ); Sun, 6 Oct 2019 03:55:51 -0400 Received: from archlinux (cpc149474-cmbg20-2-0-cust94.5-4.cable.virginm.net [82.4.196.95]) (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 9B7CB20867; Sun, 6 Oct 2019 07:55:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570348550; bh=cTgYkYNvEZUYhQCHpW90nyT6f6A7TtppG794I28rVTQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=iEKJ+J1ZgM2slbrLYGR/XpKcffRRCaVg/tc3k8FA8k0vE1CRYhhO4sPxRJRYi7s1P VluT2TbuWcb4ec+bBPr8/ZVsYQpbvJQBmfGwoE1P2LlIe4RVDi2zJoOK7gBSM8hXjt KXZ2ozaNJvYiBSssUj/soQplrBzWHuicQvGTIs8c= Date: Sun, 6 Oct 2019 08:55:45 +0100 From: Jonathan Cameron To: Andrea Merello Cc: patrick.havelange@essensium.com, paresh.chaudhary@rockwellcollins.com, pmeerw@pmeerw.net, lars@metafoo.de, knaack.h@gmx.de, matthew.weber@rockwellcollins.com, colin.king@canonical.com, linux-iio@vger.kernel.org Subject: Re: [PATCH 2/3] iio: max31856: add support for configuring the HW averaging Message-ID: <20191006085545.2df79667@archlinux> In-Reply-To: <20190923121714.13672-3-andrea.merello@gmail.com> References: <20190923121714.13672-1-andrea.merello@gmail.com> <20190923121714.13672-3-andrea.merello@gmail.com> X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org 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. 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, > }; >