From patchwork Mon Sep 23 12:17:12 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrea Merello X-Patchwork-Id: 11156665 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3F48E17D4 for ; Mon, 23 Sep 2019 12:17:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E0E4214DA for ; Mon, 23 Sep 2019 12:17:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="YlLIxetR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732114AbfIWMRu (ORCPT ); Mon, 23 Sep 2019 08:17:50 -0400 Received: from mail-wr1-f65.google.com ([209.85.221.65]:34537 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732154AbfIWMRu (ORCPT ); Mon, 23 Sep 2019 08:17:50 -0400 Received: by mail-wr1-f65.google.com with SMTP id a11so13734893wrx.1 for ; Mon, 23 Sep 2019 05:17:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=tuV3QwoICkxsxXj6MRCa5YPaGE02cRujJRq5EjeTc48=; b=YlLIxetRqPNhHoOE5I9RCGCWOtjZ+cKWOL+PJWEQtF+eN+FadhWpBsZTIb6/lyvfSw f7jpawcytfDP+47riAdSKBpbqRysMlUvLdNAM8qHzWAtODdSw1LUepuk1ohQVthJQ9x0 t6Ws6oRerRSjp+JhJWjgK8eGEo1FdouM3cZr2ynS4CJJ9NbDnwcsB2tEtoXeStPlypug 2VIZ4dOo8g7t71Pm7TgUhygPVzRGH8rv0l1UNnU5M7gSjCnnLF9ALf4UGtJqRDrWz5vw t81PgE+GelISzO7se72YTwU4WmudItIY+Moib2FOjIH3wwwqe2eS7AMIOHcOt98DcrAQ U9Jw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=tuV3QwoICkxsxXj6MRCa5YPaGE02cRujJRq5EjeTc48=; b=Q4wQgdcfwM73lpWTDsNdVknHCytKOeSwHkvQl6xelmy5gW8Bs5RKgr0NyxqhvjwOhq 28eaO4z2hYg1Nkb2Zk6YTwqY80VjgdWWmGtBtf9RZ8opK55M2wtGPNcXaCAc111IsSnD SwS5GjJj82RMSYSeo+zaxHDeiTJ0nAiIBW2Qt1AJlMBHDiAPLPrOIxU9OGDCqqLunURo AkjNvs/vxDNs8dEssjyOeKm1L/G5nHBU/5mv2Cvq9+w34MGks11lCKb8f13BDauDeIR7 ZGIcwR7yJQX1SthoZ8pGKJBxg3zPRm1qPftc8Tugtz1FDmASay/v5YZeD1aRlnE7uSbQ 23wg== X-Gm-Message-State: APjAAAUhXpWEFAvmJmvOfhLZ0JM+oga4XtS/ooMAtPo1ih3TWsRelIZe n4TYhAHsEylPfuq0xG9ao4M= X-Google-Smtp-Source: APXvYqysgyKmGI6lMl+vW8RghRiq24OIIX5NDvdzEBFX1zBrsL5zbWEMPUV1VY/kQFevZJg9gZAsCw== X-Received: by 2002:adf:e390:: with SMTP id e16mr21570355wrm.29.1569241067423; Mon, 23 Sep 2019 05:17:47 -0700 (PDT) Received: from NewMoon.iit.local ([90.147.180.254]) by smtp.gmail.com with ESMTPSA id a7sm11342836wra.43.2019.09.23.05.17.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Sep 2019 05:17:46 -0700 (PDT) From: Andrea Merello To: jic23@kernel.org, patrick.havelange@essensium.com, paresh.chaudhary@rockwellcollins.com, pmeerw@pmeerw.net, lars@metafoo.de, knaack.h@gmx.de, matthew.weber@rockwellcollins.com Cc: colin.king@canonical.com, linux-iio@vger.kernel.org, Andrea Merello Subject: [PATCH 1/3] iio: max31856: add option for setting mains filter rejection frequency Date: Mon, 23 Sep 2019 14:17:12 +0200 Message-Id: <20190923121714.13672-2-andrea.merello@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190923121714.13672-1-andrea.merello@gmail.com> References: <20190923121714.13672-1-andrea.merello@gmail.com> Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org This sensor has an embedded notch filter for reducing interferences caused by the power mains. This filter can be tuned to reject either 50Hz or 60Hz (and harmonics). Currently the said setting is left alone (the sensor defaults to 60Hz). This patch introduces a IIO attribute that allows the user to set the said filter to the desired frequency. NOTE: this has been intentionally not tied to any DT property to allow the configuration of this setting from userspace, e.g. with a GUI or by reading a configuration file, or maybe reading a GPIO tied to a physical switch or accessing some device that can autodetect the line frequency. Signed-off-by: Andrea Merello --- drivers/iio/temperature/max31856.c | 49 ++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) diff --git a/drivers/iio/temperature/max31856.c b/drivers/iio/temperature/max31856.c index 73ed550e3fc9..d12613f7ba3c 100644 --- a/drivers/iio/temperature/max31856.c +++ b/drivers/iio/temperature/max31856.c @@ -23,6 +23,7 @@ #define MAX31856_CR0_1SHOT BIT(6) #define MAX31856_CR0_OCFAULT BIT(4) #define MAX31856_CR0_OCFAULT_MASK GENMASK(5, 4) +#define MAX31856_CR0_FILTER_50HZ BIT(0) #define MAX31856_TC_TYPE_MASK GENMASK(3, 0) #define MAX31856_FAULT_OVUV BIT(1) #define MAX31856_FAULT_OPEN BIT(0) @@ -63,6 +64,7 @@ static const struct iio_chan_spec max31856_channels[] = { struct max31856_data { struct spi_device *spi; u32 thermocouple_type; + bool filter_50hz; }; static int max31856_read(struct max31856_data *data, u8 reg, @@ -123,6 +125,11 @@ static int max31856_init(struct max31856_data *data) reg_cr0_val &= ~MAX31856_CR0_1SHOT; reg_cr0_val |= MAX31856_CR0_AUTOCONVERT; + if (data->filter_50hz) + reg_cr0_val |= MAX31856_CR0_FILTER_50HZ; + else + reg_cr0_val &= ~MAX31856_CR0_FILTER_50HZ; + return max31856_write(data, MAX31856_CR0_REG, reg_cr0_val); } @@ -249,12 +256,53 @@ static ssize_t show_fault_oc(struct device *dev, return show_fault(dev, MAX31856_FAULT_OPEN, buf); } +static ssize_t show_filter(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", data->filter_50hz ? 50 : 60); +} + +static ssize_t set_filter(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 freq; + int ret; + + ret = kstrtouint(buf, 10, &freq); + if (ret) + return ret; + + switch (freq) { + case 50: + data->filter_50hz = true; + break; + case 60: + data->filter_50hz = false; + break; + default: + return -EINVAL; + } + + 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 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, NULL, }; @@ -280,6 +328,7 @@ static int max31856_probe(struct spi_device *spi) data = iio_priv(indio_dev); data->spi = spi; + data->filter_50hz = false; spi_set_drvdata(spi, indio_dev);