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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 C12B3C4363D for ; Thu, 24 Sep 2020 11:39:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 876482344C for ; Thu, 24 Sep 2020 11:39:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=bgdev-pl.20150623.gappssmtp.com header.i=@bgdev-pl.20150623.gappssmtp.com header.b="T1YaoAIm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727533AbgIXLiz (ORCPT ); Thu, 24 Sep 2020 07:38:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59642 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727489AbgIXLiw (ORCPT ); Thu, 24 Sep 2020 07:38:52 -0400 Received: from mail-wm1-x343.google.com (mail-wm1-x343.google.com [IPv6:2a00:1450:4864:20::343]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C31EC0613D6 for ; Thu, 24 Sep 2020 04:38:52 -0700 (PDT) Received: by mail-wm1-x343.google.com with SMTP id e11so6610968wme.0 for ; Thu, 24 Sep 2020 04:38:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bgdev-pl.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=wWev9UkO42jRbRsY5byu55gJ732xfhhQhwpq7S9JN7M=; b=T1YaoAImjSA161NmXY3XnIg49iksszJrPF7tIuhTP6ZjQyLkCtUpCIVYPuM7B5gDtP Eg3r8IJ05CSZzfhRTwA/pLsKI3xrHBgyD2apE5cHKuFnn25nkfmaMBAyAYiOWzlUKWth c3aT7cK/pyohmnLEKswYslvDsnt8tlOHlpQy2lz/TU7kQKYkvUHFT2spgiiDSWWaBpUx QavhMnjVSjHbPIB//Jvm621BvjHbGi4+i2felScgwDggQP5orDoulnqo0naDgqdOT6pP gHP3EvWXmadO3h7Lb2p0rJQkv2bnb8FtTmy2Imir1TslvCtFXv8xURbZrQs8mg440P3g RbmA== 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=wWev9UkO42jRbRsY5byu55gJ732xfhhQhwpq7S9JN7M=; b=l4nEutrYudMAfYEb0R88ogO3Azb/W2xOp+b9FHy+fzcMUz/EHfLxWyEZaq4biyjAaZ CkNShcGhsJ2XZyhJqvDs/TGeD0aQWcaSY14GP4t3WbsQD0l2kPCD/1QhaHU97JhlKhd3 k3pG4X36m+Xy3ndDyv4f5pnUVP2A6Ic8rwPhTXwZEObmiSDxU+/t6NubR13vc9i9gWmR uKGvGPqRHbt9WNaJvrKn5tDGrsc4hRtN8W6wTocJVY1z850HrEGqx7MRz7M4e6QAvEXQ dUzblU274PSq7HVG69tfp44CpJe3pEgo2VxqlGo1DyUVd8UNE1to+c+M1L93guLAOIXS NWYA== X-Gm-Message-State: AOAM5312cbBXecNN53GN1yG0OL6W1xl0pG/xg2QhxWDMwpgLdF/EtGAt pvHFyHOv78PgHjOYlF5yZqEXng== X-Google-Smtp-Source: ABdhPJwrt2MlBcTP0XgtXva4MaqZyVUSBZvDLONbzEc0v8hoFE43xWtvMIUuy+87Tt9DMBZB+1SbQg== X-Received: by 2002:a1c:1902:: with SMTP id 2mr4588867wmz.26.1600947530739; Thu, 24 Sep 2020 04:38:50 -0700 (PDT) Received: from debian-brgl.home (lfbn-nic-1-68-20.w2-15.abo.wanadoo.fr. [2.15.159.20]) by smtp.gmail.com with ESMTPSA id y207sm3390133wmc.17.2020.09.24.04.38.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Sep 2020 04:38:50 -0700 (PDT) From: Bartosz Golaszewski To: Linus Walleij , Jonathan Corbet , Andy Shevchenko , Kent Gibson Cc: linux-gpio@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski Subject: [PATCH 2/9] Documentation: gpio: add documentation for gpio-mockup Date: Thu, 24 Sep 2020 13:38:35 +0200 Message-Id: <20200924113842.11670-3-brgl@bgdev.pl> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200924113842.11670-1-brgl@bgdev.pl> References: <20200924113842.11670-1-brgl@bgdev.pl> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org From: Bartosz Golaszewski There's some documentation for gpio-mockup's debugfs interface in the driver's source but it's not much. Add proper documentation for this testing module. Signed-off-by: Bartosz Golaszewski --- .../admin-guide/gpio/gpio-mockup.rst | 50 +++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 Documentation/admin-guide/gpio/gpio-mockup.rst diff --git a/Documentation/admin-guide/gpio/gpio-mockup.rst b/Documentation/admin-guide/gpio/gpio-mockup.rst new file mode 100644 index 000000000000..9fa1618b3adc --- /dev/null +++ b/Documentation/admin-guide/gpio/gpio-mockup.rst @@ -0,0 +1,50 @@ +.. SPDX-License-Identifier: GPL-2.0-only + +GPIO Testing Driver +=================== + +The GPIO Testing Driver (gpio-mockup) provides a way to create simulated GPIO +chips for testing purposes. The lines exposed by these chips can be accessed +using the standard GPIO character device interface as well as manipulated +using the dedicated debugfs directory structure. + +Creating simulated chips using module params +-------------------------------------------- + +When loading the gpio-mockup driver a number of parameters can be passed to the +module. + + gpio_mockup_ranges + + This parameter takes an argument in the form of an array of integer + pairs. Each pair defines the base GPIO number (if any) and the number + of lines exposed by the chip. If the base GPIO is -1, the gpiolib + will assign it automatically. + + Example: gpio_mockup_ranges=-1,8,-1,16,405,4 + + The line above creates three chips. The first one will expose 8 lines, + the second 16 and the third 4. The base GPIO for the third chip is set + to 405 while for two first chips it will be assigned automatically. + + gpio_named_lines + + This parameter doesn't take any arguments. It lets the driver know that + GPIO lines exposed by it should be named. + + The name format is: gpio-mockup-X-Y where X is mockup chip's ID + and Y is the line offset. + +Manipulating simulated lines +---------------------------- + +Each mockup chip creates its own subdirectory in /sys/kernel/debug/gpio-mockup/. +The directory is named after the chip's label. A symlink is also created, named +after the chip's name, which points to the label directory. + +Inside each subdirectory, there's a separate attribute for each GPIO line. The +name of the attribute represents the line's offset in the chip. + +Reading from a line attribute returns the current value. Writing to it (0 or 1) +changes the configuration of the simulated pull-up/pull-down resistor +(1 - pull-up, 0 - pull-down). -- 2.26.1