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=-15.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, 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 4F54EC433E0 for ; Wed, 30 Dec 2020 14:43:34 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E82D421919 for ; Wed, 30 Dec 2020 14:43:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E82D421919 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=zBqNmintvZi1G0OVe+bejJBKKWmgZpwSPZuWfiSehk8=; b=wD79n20qb5q2+jYyDa3tZ1/2s Z11wjhTE7aRc+q4tV82IcaHCW2HZdZfTlqnMOdL4jWimMf5tb/EmdYMVkt6oV5yr+GKFT2jSJO7JU +J7hw25+l9QoBcqbF99X2ui52pbq1aY0WI2/AfOd1OaOnMqqaX3xgN2ufHur+S1doMVtd6finQMNo I6YfYkkga0gUcudWhSilkM0dgmq9JPS/JoglPZ9GTyVNrmwQqp23BAH8LPoqfYjjsHyefqifzaHGH uViRxvcSPXfE8QbTnRFGFaOS9siVMLghS3kGDJGj+/cCPNUQlWIMS8dKXzX7Fz03v6mDZLu0J83lF CeGAYh+0w==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kucfq-0007X8-5K; Wed, 30 Dec 2020 14:42:02 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kucfn-0007Wk-PP for linux-arm-kernel@lists.infradead.org; Wed, 30 Dec 2020 14:42:01 +0000 Received: from archlinux (cpc108967-cmbg20-2-0-cust86.5-4.cable.virginm.net [81.101.6.87]) (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 11B4421919; Wed, 30 Dec 2020 14:41:55 +0000 (UTC) Date: Wed, 30 Dec 2020 14:41:52 +0000 From: Jonathan Cameron To: William Breathitt Gray Subject: Re: [PATCH v7 2/5] docs: counter: Update to reflect sysfs internalization Message-ID: <20201230144152.7800399d@archlinux> In-Reply-To: <4a1bdcdea3826d9b1a8af3d9318ac952693f400c.1608935587.git.vilhelm.gray@gmail.com> References: <4a1bdcdea3826d9b1a8af3d9318ac952693f400c.1608935587.git.vilhelm.gray@gmail.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201230_094159_994949_F52A708A X-CRM114-Status: GOOD ( 39.88 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kamel.bouhara@bootlin.com, gwendal@chromium.org, a.fatoum@pengutronix.de, david@lechnology.com, linux-iio@vger.kernel.org, patrick.havelange@essensium.com, alexandre.belloni@bootlin.com, mcoquelin.stm32@gmail.com, linux-kernel@vger.kernel.org, kernel@pengutronix.de, fabrice.gasnier@st.com, syednwaris@gmail.com, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, alexandre.torgue@st.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 25 Dec 2020 19:15:35 -0500 William Breathitt Gray wrote: > The Counter subsystem architecture and driver implementations have > changed in order to handle Counter sysfs interactions in a more > consistent way. This patch updates the Generic Counter interface > documentation to reflect the changes. > > Signed-off-by: William Breathitt Gray > --- > Documentation/ABI/testing/sysfs-bus-counter | 9 +- > Documentation/driver-api/generic-counter.rst | 242 ++++++++++++++----- > 2 files changed, 184 insertions(+), 67 deletions(-) > > diff --git a/Documentation/ABI/testing/sysfs-bus-counter b/Documentation/ABI/testing/sysfs-bus-counter > index 566bd99fe0a5..1820ce2f9183 100644 > --- a/Documentation/ABI/testing/sysfs-bus-counter > +++ b/Documentation/ABI/testing/sysfs-bus-counter > @@ -219,7 +219,14 @@ What: /sys/bus/counter/devices/counterX/signalY/signal > KernelVersion: 5.2 > Contact: linux-iio@vger.kernel.org > Description: > - Signal data of Signal Y represented as a string. > + Signal level state of Signal Y. The following signal level > + states are available: > + > + low: > + Low level state. > + > + high: > + High level state. > > What: /sys/bus/counter/devices/counterX/signalY/name > KernelVersion: 5.2 > diff --git a/Documentation/driver-api/generic-counter.rst b/Documentation/driver-api/generic-counter.rst > index b02c52cd69d6..b842ddbbd8a0 100644 > --- a/Documentation/driver-api/generic-counter.rst > +++ b/Documentation/driver-api/generic-counter.rst > @@ -250,8 +250,8 @@ for defining a counter device. > .. kernel-doc:: drivers/counter/counter.c > :export: > > -Implementation > -============== > +Driver Implementation > +===================== > > To support a counter device, a driver must first allocate the available > Counter Signals via counter_signal structures. These Signals should > @@ -267,25 +267,59 @@ respective counter_count structure. These counter_count structures are > set to the counts array member of an allocated counter_device structure > before the Counter is registered to the system. > > -Driver callbacks should be provided to the counter_device structure via > -a constant counter_ops structure in order to communicate with the > -device: to read and write various Signals and Counts, and to set and get > -the "action mode" and "function mode" for various Synapses and Counts > -respectively. > +Driver callbacks must be provided to the counter_device structure in > +order to communicate with the device: to read and write various Signals > +and Counts, and to set and get the "action mode" and "function mode" for > +various Synapses and Counts respectively. > > A defined counter_device structure may be registered to the system by > passing it to the counter_register function, and unregistered by passing > it to the counter_unregister function. Similarly, the > -devm_counter_register and devm_counter_unregister functions may be used > -if device memory-managed registration is desired. > - > -Extension sysfs attributes can be created for auxiliary functionality > -and data by passing in defined counter_device_ext, counter_count_ext, > -and counter_signal_ext structures. In these cases, the > -counter_device_ext structure is used for global/miscellaneous exposure > -and configuration of the respective Counter device, while the > -counter_count_ext and counter_signal_ext structures allow for auxiliary > -exposure and configuration of a specific Count or Signal respectively. > +devm_counter_register function may be used if device memory-managed > +registration is desired. > + > +The struct counter_comp structure is used to define counter extensions > +for Signals, Synapses, and Counts. > + > +The "type" member specifies the type of high-level data (e.g. BOOL, > +COUNT_DIRECTION, etc.) handled by this extension. The "`*_read`" and > +"`*_write`" members can then be set by the counter device driver with > +callbacks to handle that data using native C data types (i.e. u8, u64, > +etc.). > + > +Convenience macros such as `COUNTER_COMP_COUNT_U64` are provided for use > +by driver authors. In particular, driver authors are expected to use > +the provided macros for standard Counter subsystem attributes in order > +to maintain a consistent interface for userspace. For example, a counter > +device driver may define several standard attributes like so:: > + > + struct counter_comp count_ext[] = { > + COUNTER_COMP_DIRECTION(count_direction_read), > + COUNTER_COMP_ENABLE(count_enable_read, count_enable_write), > + COUNTER_COMP_CEILING(count_ceiling_read, count_ceiling_write), > + }; > + > +This makes it simple to see, add, and modify the attributes that are > +supported by this driver ("direction", "enable", and "ceiling") and to > +maintain this code without getting lost in a web of struct braces. > + > +Callbacks must match the function type expected for the respective > +component or extension. These function types are defined in the struct > +counter_comp structure as the "`*_read`" and "`*_write`" union members. > + > +The corresponding callback prototypes for the extensions mentioned in > +the previous example above would be:: > + > + int count_direction_read(struct counter_device *counter, > + struct counter_count *count, u8 *direction); > + int count_enable_read(struct counter_device *counter, > + struct counter_count *count, u8 *enable); > + int count_enable_write(struct counter_device *counter, > + struct counter_count *count, u8 enable); > + int count_ceiling_read(struct counter_device *counter, > + struct counter_count *count, u64 *ceiling); > + int count_ceiling_write(struct counter_device *counter, > + struct counter_count *count, u64 ceiling); > > Determining the type of extension to create is a matter of scope. > > @@ -313,52 +347,128 @@ Determining the type of extension to create is a matter of scope. > chip overheated via a device extension called "error_overtemp": > /sys/bus/counter/devices/counterX/error_overtemp > > -Architecture > -============ > - > -When the Generic Counter interface counter module is loaded, the > -counter_init function is called which registers a bus_type named > -"counter" to the system. Subsequently, when the module is unloaded, the > -counter_exit function is called which unregisters the bus_type named > -"counter" from the system. > - > -Counter devices are registered to the system via the counter_register > -function, and later removed via the counter_unregister function. The > -counter_register function establishes a unique ID for the Counter > -device and creates a respective sysfs directory, where X is the > -mentioned unique ID: > - > - /sys/bus/counter/devices/counterX > - > -Sysfs attributes are created within the counterX directory to expose > -functionality, configurations, and data relating to the Counts, Signals, > -and Synapses of the Counter device, as well as options and information > -for the Counter device itself. > - > -Each Signal has a directory created to house its relevant sysfs > -attributes, where Y is the unique ID of the respective Signal: > - > - /sys/bus/counter/devices/counterX/signalY > - > -Similarly, each Count has a directory created to house its relevant > -sysfs attributes, where Y is the unique ID of the respective Count: > - > - /sys/bus/counter/devices/counterX/countY > - > -For a more detailed breakdown of the available Generic Counter interface > -sysfs attributes, please refer to the > -Documentation/ABI/testing/sysfs-bus-counter file. > - > -The Signals and Counts associated with the Counter device are registered > -to the system as well by the counter_register function. The > -signal_read/signal_write driver callbacks are associated with their > -respective Signal attributes, while the count_read/count_write and > -function_get/function_set driver callbacks are associated with their > -respective Count attributes; similarly, the same is true for the > -action_get/action_set driver callbacks and their respective Synapse > -attributes. If a driver callback is left undefined, then the respective > -read/write permission is left disabled for the relevant attributes. > - > -Similarly, extension sysfs attributes are created for the defined > -counter_device_ext, counter_count_ext, and counter_signal_ext > -structures that are passed in. > +Subsystem Architecture > +====================== > + > +Counter drivers pass and take data natively (i.e. `u8`, `u64`, etc.) and > +the shared counter module handles the translation between the sysfs > +interface. Same point as raised in previous patch description. > This gurantees a standard userspace interface for all counter Spell check this file. guarantees > +drivers, and helps generalize the Generic Counter driver ABI in order to > +support the Generic Counter chrdev interface without significant changes > +to the existing counter drivers. I would modify this to assume you've already done the chrdev interface. "and enables a Generic Counter chrdev interface without..." > + > +A high-level view of how a count value is passed down from a counter > +driver is exemplified by the following. The driver callbacks are first > +registered to the Counter core component for use by the Counter > +userspace interface components:: > + > + Driver callbacks registration: > + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > + +----------------------------+ > + | Counter device driver | That tab again ;) > + +----------------------------+ > + | Processes data from device | > + +----------------------------+ > + | > + ------------------- > + / driver callbacks / > + ------------------- > + | > + V > + +----------------------+ > + | Counter core | > + +----------------------+ > + | Routes device driver | > + | callbacks to the | > + | userspace interfaces | > + +----------------------+ > + | > + ------------------- > + / driver callbacks / > + ------------------- > + | > + +---------------+ > + | > + V > + +--------------------+ > + | Counter sysfs | > + +--------------------+ > + | Translates to the | > + | standard Counter | > + | sysfs output | > + +--------------------+ > + > +Thereafter, data can be transferred directly between the Counter device > +driver and Counter userspace interface:: > + > + Count data request: > + ~~~~~~~~~~~~~~~~~~~ > + ---------------------- > + / Counter device \ > + +----------------------+ > + | Count register: 0x28 | > + +----------------------+ > + | > + ----------------- > + / raw count data / > + ----------------- > + | > + V > + +----------------------------+ > + | Counter device driver | > + +----------------------------+ > + | Processes data from device | > + |----------------------------| > + | Type: u64 | > + | Value: 42 | > + +----------------------------+ > + | > + ---------- > + / u64 / > + ---------- > + | > + +---------------+ > + | > + V > + +--------------------+ > + | Counter sysfs | > + +--------------------+ > + | Translates to the | > + | standard Counter | > + | sysfs output | > + |--------------------| > + | Type: const char * | > + | Value: "42" | > + +--------------------+ > + | > + --------------- > + / const char * / > + --------------- > + | > + V > + +--------------------------------------------------+ > + | `/sys/bus/counter/devices/counterX/countY/count` | > + +--------------------------------------------------+ > + \ Count: "42" / > + -------------------------------------------------- > + > +There are three primary components involved: > + > +Counter device driver > +--------------------- > +Communicates with the hardware device to read/write data; e.g. counter > +drivers for quadrature encoders, timers, etc. > + > +Counter core > +------------ > +Registers the counter device driver to the system so that the respective > +callbacks are called during userspace interaction. > + > +Counter sysfs > +------------- > +Translates counter data to the standard Counter sysfs interface format > +and vice versa. > + > +Please refer to the `Documentation/ABI/testing/sysfs-bus-counter` file > +for a detailed breakdown of the available Generic Counter interface > +sysfs attributes. Otherwise LGTM. Thanks, Jonathan _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel