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=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 DB6C3C3F2D4 for ; Sun, 1 Mar 2020 20:15:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B426321744 for ; Sun, 1 Mar 2020 20:15:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583093709; bh=xtHhfpQG1yNXRNMNT7O6zsFDLkfakTVUMH4y2fI2GJA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=i/OlNrYFbOOEN0B66V8N8p4HBQyTRox9JwNrvr2Zov5XOsR2iV8FOVNyfMf3V5/a9 ncw3PImOdK8tvxHY5K0CTgY0GcnPc8cioEtLDbyNXBmVg+8t6FMiUmKdtuQZbtfQKJ p3GE6WL/ahGpX+HTJN1VRLwv5XdU2TOozf/IdICc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726592AbgCAUPI (ORCPT ); Sun, 1 Mar 2020 15:15:08 -0500 Received: from mail.kernel.org ([198.145.29.99]:37664 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726050AbgCAUPI (ORCPT ); Sun, 1 Mar 2020 15:15:08 -0500 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 4A80C21744; Sun, 1 Mar 2020 20:15:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583093707; bh=xtHhfpQG1yNXRNMNT7O6zsFDLkfakTVUMH4y2fI2GJA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=gxakopvh+tUV+Eu06cPEBz16rMeAWxtnUb2ghQOQszKvCG8FWytrO8Ix8JVJOJj3m 0gSKhdnXZWAxm3fqosod1nis+1uEwyiGyFBXiGcuS7koocNlsuV7RFAKQVbZS952J0 CqChhPwbbOMQO8THcMqqGo4ILvG15zZIECN74I7E= Date: Sun, 1 Mar 2020 20:14:58 +0000 From: Jonathan Cameron To: William Breathitt Gray Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] counter: 104-quad-8: Support Differential Encoder Cable Status Message-ID: <20200301201458.4dcce64c@archlinux> In-Reply-To: <20200222154340.89464-1-vilhelm.gray@gmail.com> References: <20200222154340.89464-1-vilhelm.gray@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-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 22 Feb 2020 10:43:40 -0500 William Breathitt Gray wrote: > The ACCES 104-QUAD-8 series provides status information about the > connection state of the differential encoder cable inputs. This patch > implements support to expose such information from these devices. > > Signed-off-by: William Breathitt Gray Hi William, Couple of things on the interface... > --- > .../ABI/testing/sysfs-bus-counter-104-quad-8 | 12 ++++++ > drivers/counter/104-quad-8.c | 38 +++++++++++++++++++ > 2 files changed, 50 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-bus-counter-104-quad-8 b/Documentation/ABI/testing/sysfs-bus-counter-104-quad-8 > index 46b1f33b2fce..492b3e98f369 100644 > --- a/Documentation/ABI/testing/sysfs-bus-counter-104-quad-8 > +++ b/Documentation/ABI/testing/sysfs-bus-counter-104-quad-8 > @@ -1,3 +1,15 @@ > +What: /sys/bus/counter/devices/counterX/cable_status > +KernelVersion: 5.7 > +Contact: linux-iio@vger.kernel.org > +Description: > + Differential encoder cable status; bits 0 through 7 > + correspond to channels 1 through 8. Writing a 0 to the > + corresponding bit will enable the status of the > + respective channel. I'm never personally that keen on cases where a sysfs file doesn't have inherent 'obviousness'. In this case we have a bitmap that doesn't make that clear and that also that doesn't have particularly obviously meaning either on the write or read. Hmm. So if you wanted to keep it as a bitmap perhaps something like... cable_test_bitmap So a 1 (or true) would be a successful cable test on read. However that is still not obviously something that needs an enable. It think you need to split it. *_enable *_status Next question is whether it should be a map like this? sysfs rules are usually one value to one sysfs file. It might seem wasteful but I'd like to see something like cable0_test_enable cable0_test_status cable7_test_enable cable7_test_status I haven't thought about whether this could be fit better with the counter ABI but something along those lines! > + > + Logic 0 = cable fault (not connected or loose wires) > + Logic 1 = cable connection good or cable fault disabled > + > What: /sys/bus/counter/devices/counterX/signalY/index_polarity > KernelVersion: 5.2 > Contact: linux-iio@vger.kernel.org > diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c > index 17e67a84777d..1cbaf7e100a3 100644 > --- a/drivers/counter/104-quad-8.c > +++ b/drivers/counter/104-quad-8.c > @@ -56,6 +56,7 @@ struct quad8_iio { > > #define QUAD8_REG_CHAN_OP 0x11 > #define QUAD8_REG_INDEX_INPUT_LEVELS 0x16 > +#define QUAD8_DIFF_ENCODER_CABLE_STATUS 0x17 > /* Borrow Toggle flip-flop */ > #define QUAD8_FLAG_BT BIT(0) > /* Carry Toggle flip-flop */ > @@ -1268,6 +1269,42 @@ static struct counter_count quad8_counts[] = { > QUAD8_COUNT(7, "Channel 8 Count") > }; > > +static ssize_t quad8_cable_status_read(struct counter_device *counter, > + void *private, char *buf) > +{ > + const struct quad8_iio *const priv = counter->priv; > + unsigned int status; > + > + status = inb(priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS); > + > + return sprintf(buf, "0x%X\n", status); > +} > + > +static ssize_t quad8_cable_status_write(struct counter_device *counter, > + void *private, const char *buf, > + size_t len) > +{ > + struct quad8_iio *const priv = counter->priv; > + u8 enable; > + int ret; > + > + ret = kstrtou8(buf, 0, &enable); > + if (ret) > + return ret; > + > + outb(enable, priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS); > + > + return len; > +} > + > +static const struct counter_device_ext quad8_device_ext[] = { > + { > + .name = "cable_status", > + .read = quad8_cable_status_read, > + .write = quad8_cable_status_write > + } > +}; > + > static int quad8_probe(struct device *dev, unsigned int id) > { > struct iio_dev *indio_dev; > @@ -1304,6 +1341,7 @@ static int quad8_probe(struct device *dev, unsigned int id) > quad8iio->counter.num_counts = ARRAY_SIZE(quad8_counts); > quad8iio->counter.signals = quad8_signals; > quad8iio->counter.num_signals = ARRAY_SIZE(quad8_signals); > + quad8iio->counter.ext = quad8_device_ext; > quad8iio->counter.priv = quad8iio; > quad8iio->base = base[id]; >