From patchwork Mon Sep 28 10:41:48 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bartosz Golaszewski X-Patchwork-Id: 1372513 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-gpio-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=bgdev.pl Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=bgdev-pl.20150623.gappssmtp.com header.i=@bgdev-pl.20150623.gappssmtp.com header.a=rsa-sha256 header.s=20150623 header.b=g25S92Gz; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4C0JxG429rz9s0b for ; Mon, 28 Sep 2020 20:42:10 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726630AbgI1KmJ (ORCPT ); Mon, 28 Sep 2020 06:42:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726566AbgI1KmD (ORCPT ); Mon, 28 Sep 2020 06:42:03 -0400 Received: from mail-wm1-x342.google.com (mail-wm1-x342.google.com [IPv6:2a00:1450:4864:20::342]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 13896C061755 for ; Mon, 28 Sep 2020 03:42:03 -0700 (PDT) Received: by mail-wm1-x342.google.com with SMTP id k18so621789wmj.5 for ; Mon, 28 Sep 2020 03:42:03 -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=BgQC3n53i35n7GC4c6lOV6W434EKfBGkaRy/2vzORco=; b=g25S92GzFTtlvrXh1qKrS/Vwlmclx80rOqSPIoXFYXySdro3WbP05KxXTAPR6v3exM ktTM+IJme5cRnb4LbYPLmz1mXORBY7M91DOyzGSbReyWETCpIyAfMA1stxJJLtDtxYak OdXu930qd9y3kFxYNsvMaDZN1sUYXRasTgjeflLvqROirlEIEi47pdPrdolGMO9W2Mfl saNiCjsYw3hpDcf052MHVKMu6/CP3RWUrd42qbQ+WEMUe49rppw728yuoFN9a1iTi/25 EGAsht8jzipIbdyIVTys8PMyYmtjgtrJjoL3DwTLRgFqB4fNUsT6bnABqUL1G+AtQitg uhOg== 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=BgQC3n53i35n7GC4c6lOV6W434EKfBGkaRy/2vzORco=; b=Qy3XvgPAyc3kft9hRlFBg0FxN8g/sM00aAqHSnFZ87M1KeDG3INkMyG24003gDFemX lW1tX7IgbuVsqT/0nsY6QWOyJTKDk3sedl5srXecg1Mg1Kse9e5c+a1h2Fb6FRfTTGDA VkHvzwMfUwuB4lBSA5wcoC4msx1Vvl3z8Jlwxx74eoTS47Dm/bprJX0Nc5L2DXKx6wB2 OqfbiYRPdS0AS92Q6aeB7G0bub0USy42DwYQQ98H4le6C14YEVlahJIZrC976WE5pSmS eha9l1dwyLF6IJy1FUBQLu7o3q2GzsaEuOMcguQpw8g4JKUQVJzxXEXZLR9Av1KaV6ys T9fg== X-Gm-Message-State: AOAM532VsNuGet4T6sLODHcod7FEethVntQJo8a+QAeGWTHUgzYC+XdO L/5/t7UFxOuETOPT5oJUeGpxNg== X-Google-Smtp-Source: ABdhPJzuoHu8hiPRyruz0R0GxX7FPtBX6BtsAj+v2MOxtfNzI1H20bJDYnfNZISzWIcqTHi2x057Ug== X-Received: by 2002:a1c:544c:: with SMTP id p12mr963978wmi.170.1601289721775; Mon, 28 Sep 2020 03:42:01 -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 f14sm939258wrt.53.2020.09.28.03.42.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Sep 2020 03:42:01 -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 v2 2/9] Documentation: gpio: add documentation for gpio-mockup Date: Mon, 28 Sep 2020 12:41:48 +0200 Message-Id: <20200928104155.7385-3-brgl@bgdev.pl> X-Mailer: git-send-email 2.26.1 In-Reply-To: <20200928104155.7385-1-brgl@bgdev.pl> References: <20200928104155.7385-1-brgl@bgdev.pl> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-gpio@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 Reviewed-by: Andy Shevchenko --- .../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).