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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C70B2CCA480 for ; Sun, 19 Jun 2022 19:01:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236999AbiFSS7d (ORCPT ); Sun, 19 Jun 2022 14:59:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232717AbiFSS7X (ORCPT ); Sun, 19 Jun 2022 14:59:23 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B00D2BC8E for ; Sun, 19 Jun 2022 11:59:22 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4DAF961173 for ; Sun, 19 Jun 2022 18:59:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 97FCEC3411D; Sun, 19 Jun 2022 18:59:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1655665161; bh=9RQ8/CTto7dmgoaUjBzqPiKHHGY5pdftRSaci1xH7Vc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=G+LXDNpSR/662JCodU99Gpw22SjQD7vxlOP3sBz4VIlFeipu1CV/HGS19I7SyDREy TIWASi6BqvHhMLR7V1V8zr5Kbm6Jtq93ZHVatlIeHRgYREMUPqv10v3h1NHN8mjO0U qGcLFpjvMEm2Xpbc7iRVgKiy6SNAH56ozGqXEQqkunhhhKRRspUOalBeYIzIDcDX4x S3mq2HakFZhMi8RIInSjC/kky2RiLmKNoneYcQfdzlj1vZXif+s6oxOdP/h5vkvKT+ jsdVbjswA0zTfM+FANEQ9bxO0HkmNal7SMYYl+fK2ppjaujzlD7+NmgT7KKhF06+N1 2aNt8+XwZyEGQ== From: Jonathan Cameron To: linux-iio@vger.kernel.org, Andy Shevchenko , Peter Rosin Cc: Michael Hennerich , Lars-Peter Clausen , Vincent Whitchurch , Jonathan Cameron Subject: [PATCH v2 11/17] iio: core: Introduce _inputoffset for differential channels Date: Sun, 19 Jun 2022 19:58:33 +0100 Message-Id: <20220619185839.1363503-12-jic23@kernel.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220619185839.1363503-1-jic23@kernel.org> References: <20220619185839.1363503-1-jic23@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org From: Jonathan Cameron Address an ABI gap for device where the offset of both lines in a differential pair may be controlled so as to allow a wider range of inputs, but without having any direct effect of the differential measurement. _offset cannot be used as to remain in line with existing usage, userspace would be expected to apply it as (_raw + _offset) * scale whereas _inputoffset is not. Similarly calibbias is expected to tweak the measurement seen, not the adjust the two lines of the differential pair. Needed for in_capacitanceX-capacitanceY_inputoffset for the AD7746 CDC driver. Signed-off-by: Jonathan Cameron --- I''m not entirely happy with the naming on this one, so if anyone has a better idea I'm definitely open to it! --- Documentation/ABI/testing/sysfs-bus-iio | 13 +++++++++++++ drivers/iio/industrialio-core.c | 1 + include/linux/iio/types.h | 1 + 3 files changed, 15 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio index d3a0c0ef8948..132eb4e849f9 100644 --- a/Documentation/ABI/testing/sysfs-bus-iio +++ b/Documentation/ABI/testing/sysfs-bus-iio @@ -204,6 +204,19 @@ Description: is required is a consistent labeling. Units after application of scale and offset are nanofarads. +What: /sys/.../iio:deviceX/in_capacitableY-capacitanceZ_inputoffset +KernelVersion: 5.19 +Contact: linux-iio@vger.kernel.org +Description: + For differential channels, this an offset that is applied + equally to both inputs. As the reading is of the difference + between the two inputs this should not be applied to the _raw + reading by userspace (unlike _offset) and unlike calibbias + it does not affect the differential value measured because + the effect of _inputoffset cancels out across the two inputs + that make up the differential pair. It is expressed with + the same scaling as _raw. + What: /sys/bus/iio/devices/iio:deviceX/in_temp_raw What: /sys/bus/iio/devices/iio:deviceX/in_tempX_raw What: /sys/bus/iio/devices/iio:deviceX/in_temp_x_raw diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c index 6b401f63805f..ad1c2354502d 100644 --- a/drivers/iio/industrialio-core.c +++ b/drivers/iio/industrialio-core.c @@ -168,6 +168,7 @@ static const char * const iio_chan_info_postfix[] = { [IIO_CHAN_INFO_OVERSAMPLING_RATIO] = "oversampling_ratio", [IIO_CHAN_INFO_THERMOCOUPLE_TYPE] = "thermocouple_type", [IIO_CHAN_INFO_CALIBAMBIENT] = "calibambient", + [IIO_CHAN_INFO_INPUTOFFSET] = "inputoffset", }; /** * iio_device_id() - query the unique ID for the device diff --git a/include/linux/iio/types.h b/include/linux/iio/types.h index a7aa91f3a8dc..c7f79a251a14 100644 --- a/include/linux/iio/types.h +++ b/include/linux/iio/types.h @@ -63,6 +63,7 @@ enum iio_chan_info_enum { IIO_CHAN_INFO_OVERSAMPLING_RATIO, IIO_CHAN_INFO_THERMOCOUPLE_TYPE, IIO_CHAN_INFO_CALIBAMBIENT, + IIO_CHAN_INFO_INPUTOFFSET, }; #endif /* _IIO_TYPES_H_ */ -- 2.36.1