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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 7C505C35656 for ; Fri, 21 Feb 2020 16:35:33 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 4F7D5208E4 for ; Fri, 21 Feb 2020 16:35:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4F7D5208E4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-m68k.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:32850 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j5BH2-0004ju-FR for qemu-devel@archiver.kernel.org; Fri, 21 Feb 2020 11:35:32 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:50061) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j5BFo-0003P6-3Q for qemu-devel@nongnu.org; Fri, 21 Feb 2020 11:34:17 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j5BFm-00016r-Rb for qemu-devel@nongnu.org; Fri, 21 Feb 2020 11:34:16 -0500 Received: from mail-oi1-f196.google.com ([209.85.167.196]:36931) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1j5BFm-00016P-NQ for qemu-devel@nongnu.org; Fri, 21 Feb 2020 11:34:14 -0500 Received: by mail-oi1-f196.google.com with SMTP id q84so2155116oic.4 for ; Fri, 21 Feb 2020 08:34:14 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Q0P9tu6IOsuIOQ9cj+JFMIkV9AXW3CYPDjGH2uYPm8M=; b=VgkQ5FKw5T6havLsFdbDwyp98hOH1GPW0meFiOsFFtOiHyyzBQyJDVvuUFqQuE+xzc rQsMqIRCqWi3co+Ec8GQ+7HAOK41LZOV1wkdmEPjpmGfOaMdHrFI+eo3lgXppu0BDOpo Kv+YVQTyKhmHJTRXd66v4vzhDCySSA7LSuJdwiUuulZvA+0kAHWVwgE+7DB3YBXHeJLp r5HpTTTllU2JHTu8jlFxSDICne55mKme4t06JzxFYM5jHANl+Gcg8mzP90O99Dwtf8ql 78vAqtaXfCZsXxv7rdVBGVEd9Yw16vXlsFEWA3xFB3zfP+uYlqf5ZO7+Q7I8qNobj46J Di+Q== X-Gm-Message-State: APjAAAXdhGFFIyOq4shFaU4sOwfQVMmb+Uba+xcnkmDeWVKuH8ff3fk8 r/2fsIp9ge9FipBJdY8bJyIkhLjewZTWaUKx02Y= X-Google-Smtp-Source: APXvYqzPNoAH+zVsto1+IiOMGfW8xsdQo0YD/gttJz8Iqi71pUo1KidDfXV90s/3JMzKKHdE/I36dl+GbJbfTmLaY4E= X-Received: by 2002:aca:c4d2:: with SMTP id u201mr2773907oif.54.1582302853428; Fri, 21 Feb 2020 08:34:13 -0800 (PST) MIME-Version: 1.0 References: <20200218151812.7816-1-geert+renesas@glider.be> <20200218151812.7816-5-geert+renesas@glider.be> In-Reply-To: From: Geert Uytterhoeven Date: Fri, 21 Feb 2020 17:34:02 +0100 Message-ID: Subject: Re: [PATCH v5 4/5] docs: gpio: Add GPIO Aggregator documentation To: Randy Dunlap Content-Type: text/plain; charset="UTF-8" X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.85.167.196 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Peter Maydell , QEMU Developers , Phil Reid , Geert Uytterhoeven , Jonathan Corbet , Marc Zyngier , Linus Walleij , "open list:DOCUMENTATION" , Magnus Damm , Christoffer Dall , Linux Kernel Mailing List , Linux-Renesas , Bartosz Golaszewski , Rob Herring , Harish Jenny K N , "open list:GPIO SUBSYSTEM" , Paolo Bonzini , Alexander Graf , Eugeniu Rosca Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Randy, On Tue, Feb 18, 2020 at 7:30 PM Randy Dunlap wrote: > On 2/18/20 7:18 AM, Geert Uytterhoeven wrote: > > Document the GPIO Aggregator, and the two typical use-cases. > > > > Signed-off-by: Geert Uytterhoeven > > --- /dev/null > > +++ b/Documentation/admin-guide/gpio/gpio-aggregator.rst > > @@ -0,0 +1,102 @@ > > +.. SPDX-License-Identifier: GPL-2.0-only > > + > > +GPIO Aggregator > > +=============== > > + > > +The GPIO Aggregator allows to aggregate GPIOs, and expose them as a new > > "allows" really wants an object following the verb [although the kernel sources > and docs have many cases of it not having an object]. Something like > > allows {you, one, someone, users, a user} to aggregate Changing to: provides a mechanism to aggregate GPIOs > > +gpio_chip. This supports the following use cases. > > + > > + > > +Aggregating GPIOs using Sysfs > > +----------------------------- > > + > > +GPIO controllers are exported to userspace using /dev/gpiochip* character > > +devices. Access control to these devices is provided by standard UNIX file > > +system permissions, on an all-or-nothing basis: either a GPIO controller is > > +accessible for a user, or it is not. > > + > > +The GPIO Aggregator allows access control for individual GPIOs, by aggregating Changing to: provides access control for a set of one or more GPIOs > > +them into a new gpio_chip, which can be assigned to a group or user using > > +standard UNIX file ownership and permissions. Furthermore, this simplifies and > > +hardens exporting GPIOs to a virtual machine, as the VM can just grab the full > > +GPIO controller, and no longer needs to care about which GPIOs to grab and > > +which not, reducing the attack surface. > > +Generic GPIO Driver > > +------------------- > > + > > +The GPIO Aggregator can also be used as a generic driver for a simple > > +GPIO-operated device described in DT, without a dedicated in-kernel driver. > > +This is useful in industrial control, and is not unlike e.g. spidev, which > > +allows to communicate with an SPI device from userspace. > > allows {choose an object} to communicate Changing to: allows the user to communicate Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds