From patchwork Sat Dec 19 22:41:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Linus Walleij X-Patchwork-Id: 11983733 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 EAD7BC4361B for ; Sat, 19 Dec 2020 22:42:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AC07723426 for ; Sat, 19 Dec 2020 22:42:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726590AbgLSWmd (ORCPT ); Sat, 19 Dec 2020 17:42:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726580AbgLSWmc (ORCPT ); Sat, 19 Dec 2020 17:42:32 -0500 Received: from mail-lf1-x12a.google.com (mail-lf1-x12a.google.com [IPv6:2a00:1450:4864:20::12a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8284BC0617B0 for ; Sat, 19 Dec 2020 14:41:50 -0800 (PST) Received: by mail-lf1-x12a.google.com with SMTP id a12so14783887lfl.6 for ; Sat, 19 Dec 2020 14:41:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=82OS3pLNd8iUHESUMUxIhbTgIU37vSfj8yHnrTeu96Y=; b=TrSct3igLxzJi4/z97dqaidZkhkr01QcRXtp42P0HWxxErrIcM5M/1moUcA25uBMkf mNrdJVLAXqj09giY+T1ZqJwAIgjYCoDdPbDTKBT+4En2C9T3FbUMFEtF+9mTaMNwvxis NKO6Ff9CdJ2S54zCfljdp/ZcA5rMJaTMqwWBqmY7MzcBO6f3268Y8BN0b4KvOqnNYN1n j+eskQ8IFO79uiQ+xQqoezbn9PBNj3WA1cZU3kHwQp9OvRtgMXDDiDEdzGdeObQMMkD8 GZ/hVFflAS+6iMYqXEohsluX5AWwUloKEbcol2w2fuJGSGInIrsUT126xjVzfuczoM6g WXAA== 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:mime-version :content-transfer-encoding; bh=82OS3pLNd8iUHESUMUxIhbTgIU37vSfj8yHnrTeu96Y=; b=tPF/7umeZG7ZF62t/8D8ozf64lvq/KCkJ3qQS7d0Sb7TaKJ9LFNFOV6JfEivV+wy38 x923P2CqyrE5n5ilre6NI+oJx0iChELHAmoN9Kc9MjmpPmKse52v1GsrNsEa8WcnzH1W pPhQjYQk5gkZo7vyck2ZgL2oaDWstvubRU95eRlCRmFFGzardMiPGb7rPbTLOBT0COhd ShejuBTAcQWRqI8vxpTiryv4O5UQZPf7dH1vlhyPFaObeNKMZEjPA5yfyQVgo1uEhZqA XU32Hqx+aUJsoGKe/kC7HDr9QVhNEBZgaB8djBGR9wWEDOaiRL96IPA7nggywLYP+sIE NxtQ== X-Gm-Message-State: AOAM532Z/Q2cpOkVbW1iCeYLFg0yG5RtmIYlplOPxMcvpElUUY40IVdl 3ORSfto/SepjhU3EDqMD1VloyA== X-Google-Smtp-Source: ABdhPJyb4/OE6CfJu11wNoQYGVhclGqX8lAfSXe4t+nUc4gruT1BjchaAm8LF4hX0+js6jjOqSTVkw== X-Received: by 2002:a2e:8045:: with SMTP id p5mr4553381ljg.289.1608417708792; Sat, 19 Dec 2020 14:41:48 -0800 (PST) Received: from localhost.localdomain (c-92d7225c.014-348-6c756e10.bbcust.telenor.se. [92.34.215.146]) by smtp.gmail.com with ESMTPSA id 195sm1368982lfk.109.2020.12.19.14.41.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 19 Dec 2020 14:41:48 -0800 (PST) From: Linus Walleij To: Jean Delvare , Guenter Roeck Cc: linux-hwmon@vger.kernel.org, Linus Walleij , Peter Rosin , Chris Lesiak , Jonathan Cameron , linux-iio@vger.kernel.org Subject: [PATCH] hwmon: (ntc_thermistor): try reading processed Date: Sat, 19 Dec 2020 23:41:43 +0100 Message-Id: <20201219224143.686074-1-linus.walleij@linaro.org> X-Mailer: git-send-email 2.29.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-hwmon@vger.kernel.org Before trying the custom method of reading the sensor as raw and then converting assuming 1000 scaling, just use iio_read_channel_processed() which first tries to see if the ADC can provide a processed value directly, else reads raw and applies scaling inside of IIO using the scale attributes of the ADC. The code that hardcodes scaling to 1000 and assumes a 12bit ADC is very dubious. I keep it around here but I have a strong urge to just delete it. This gives correct readings on the AB8500 thermistor inputs used in the Ux500 HREFP520 platform for reading battery and board temperature. Cc: Peter Rosin Cc: Chris Lesiak Cc: Jonathan Cameron Cc: linux-iio@vger.kernel.org Signed-off-by: Linus Walleij --- drivers/hwmon/ntc_thermistor.c | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-) diff --git a/drivers/hwmon/ntc_thermistor.c b/drivers/hwmon/ntc_thermistor.c index 3aad62a0e661..ac0d80faddf6 100644 --- a/drivers/hwmon/ntc_thermistor.c +++ b/drivers/hwmon/ntc_thermistor.c @@ -326,18 +326,29 @@ struct ntc_data { static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata) { struct iio_channel *channel = pdata->chan; - int raw, uv, ret; + int uv, ret; - ret = iio_read_channel_raw(channel, &raw); + /* A processed voltage channel will return microvolts */ + ret = iio_read_channel_processed(channel, &uv); if (ret < 0) { - pr_err("read channel() error: %d\n", ret); - return ret; - } + int raw; - ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000); - if (ret < 0) { - /* Assume 12 bit ADC with vref at pullup_uv */ - uv = (pdata->pullup_uv * (s64)raw) >> 12; + /* + * FIXME: This fallback to using a raw read and then right + * out assume the ADC is 12 bits and hard-coding scale + * to 1000 seems a bit dangerous. Should it simply be + * deleted? + */ + ret = iio_read_channel_raw(channel, &raw); + if (ret < 0) { + pr_err("read channel() error: %d\n", ret); + return ret; + } + ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000); + if (ret < 0) { + /* Assume 12 bit ADC with vref at pullup_uv */ + uv = (pdata->pullup_uv * (s64)raw) >> 12; + } } return uv;