From patchwork Mon Apr 18 19:29:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 12817069 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 2A4E8C433F5 for ; Mon, 18 Apr 2022 19:21:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347673AbiDRTYP (ORCPT ); Mon, 18 Apr 2022 15:24:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44692 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347674AbiDRTYN (ORCPT ); Mon, 18 Apr 2022 15:24:13 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E1EE3586E for ; Mon, 18 Apr 2022 12:21:32 -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 45D3760E0A for ; Mon, 18 Apr 2022 19:21:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00905C385A7; Mon, 18 Apr 2022 19:21:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1650309691; bh=BDpIENFNuMlesggVJDYLo8PfT0a4928SawiqYoWIxFI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VqOr4+nKp+eIWxq8VYxYTKbPDeaX6Ig5ZMCHOd3AiXZCfw1kUXOqsTWgrWeBHByAq PMhO3BjFQfv9fHvI3+g66GTvRvmpjbeG7VYZNR/7mYk1BjypRC23lXPxX8eqvZAGY5 KhEoSt/+x7EYAH7azsUoAWoyn5r7ODrtmTpfFx9nZ8yhvop2m0KAI64ADFIcYL+Wx0 mYsq/VbN+/jiH1xqaHtxPxKk7uqQqslM7PB8jZXAQ8hcs1e7qlLyIxOYDTywq7Pp69 z2h1YU878V/syAtCsKG9A0u/9WuRqzuIZVoVF5EvgFdxKkOCyft894n6Anz73K/C2w 9HHm8iDmgPBCA== From: Jonathan Cameron To: linux-iio@vger.kernel.org Cc: Michael Hennerich , Lars-Peter Clausen , Vincent Whitchurch , Jonathan Cameron Subject: [PATCH 11/17] iio: core: Introduce _inputoffset for differential channels Date: Mon, 18 Apr 2022 20:29:01 +0100 Message-Id: <20220418192907.763933-12-jic23@kernel.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220418192907.763933-1-jic23@kernel.org> References: <20220418192907.763933-1-jic23@kernel.org> MIME-Version: 1.0 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 b19ff517e5d6..4fbb5a257ef5 100644 --- a/Documentation/ABI/testing/sysfs-bus-iio +++ b/Documentation/ABI/testing/sysfs-bus-iio @@ -199,6 +199,19 @@ 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 d831835770da..8aebef08ca1d 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_ */