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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham 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 4FE9CC33C8C for ; Sun, 5 Jan 2020 22:50:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 071AB2072C for ; Sun, 5 Jan 2020 22:50:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727196AbgAEWuk (ORCPT ); Sun, 5 Jan 2020 17:50:40 -0500 Received: from hostingweb31-40.netsons.net ([89.40.174.40]:37787 "EHLO hostingweb31-40.netsons.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727146AbgAEWuk (ORCPT ); Sun, 5 Jan 2020 17:50:40 -0500 Received: from [37.160.42.38] (port=5507 helo=melee.fritz.box) by hostingweb31.netsons.net with esmtpa (Exim 4.92) (envelope-from ) id 1ioEjB-00GSqI-RV; Sun, 05 Jan 2020 23:50:34 +0100 From: Luca Ceresoli To: linux-doc@vger.kernel.org, linux-i2c@vger.kernel.org Cc: Luca Ceresoli , Wolfram Sang , Peter Rosin , linux-kernel@vger.kernel.org Subject: [PATCH 03/26] docs: i2c: summary: rewrite the "terminology" section Date: Sun, 5 Jan 2020 23:49:49 +0100 Message-Id: <20200105225012.11701-3-luca@lucaceresoli.net> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200105225012.11701-1-luca@lucaceresoli.net> References: <20200105224006.10321-1-luca@lucaceresoli.net> <20200105225012.11701-1-luca@lucaceresoli.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - hostingweb31.netsons.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - lucaceresoli.net X-Get-Message-Sender-Via: hostingweb31.netsons.net: authenticated_id: luca+lucaceresoli.net/only user confirmed/virtual account not confirmed X-Authenticated-Sender: hostingweb31.netsons.net: luca@lucaceresoli.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org This section, partly dating back to the pre-git era, is somewhat unclear and partly incorrect. Rewrite it almost completely including a reference figure, concise but precise definition of each term and the paths where drivers are found. Particular care has been put in clarifying the relation between adapter and algorithm, which has no correspondence in the I2C spec terminology. Signed-off-by: Luca Ceresoli --- Documentation/i2c/i2c.svg | 1341 +++++++++++++++++++++++++++++++++ Documentation/i2c/summary.rst | 35 +- 2 files changed, 1362 insertions(+), 14 deletions(-) create mode 100644 Documentation/i2c/i2c.svg diff --git a/Documentation/i2c/i2c.svg b/Documentation/i2c/i2c.svg new file mode 100644 index 000000000000..5979405ad1c3 --- /dev/null +++ b/Documentation/i2c/i2c.svg @@ -0,0 +1,1341 @@ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + image/svg+xml + + + + + Luca Ceresoli + + + 2020 + + + + + + + + + + + + + + + I2CMaster + + + I2CSlave + + SCL + SDA + + I2CSlave + + I2CSlave + + + + + + + + + + + + VDD + + diff --git a/Documentation/i2c/summary.rst b/Documentation/i2c/summary.rst index b7d3e620155b..fc69d9567d9d 100644 --- a/Documentation/i2c/summary.rst +++ b/Documentation/i2c/summary.rst @@ -31,21 +31,28 @@ implement all the common SMBus protocol semantics or messages. Terminology =========== -When we talk about I2C, we use the following terms:: +Using the terminology from the official documentation, the I2C bus connects +one or more *master* chips and one or more *slave* chips. - Bus -> Algorithm - Adapter - Device -> Driver - Client +.. kernel-figure:: i2c.svg + :alt: Simple I2C bus with one master and 3 slaves -An Algorithm driver contains general code that can be used for a whole class -of I2C adapters. Each specific adapter driver either depends on one algorithm -driver, or includes its own implementation. + Simple I2C bus -A Driver driver (yes, this sounds ridiculous, sorry) contains the general -code to access some type of device. Each detected device gets its own -data in the Client structure. Usually, Driver and Client are more closely -integrated than Algorithm and Adapter. +A **master** chip is a node that starts communications with slaves. In the +Linux kernel implementation it is called an **adapter** or bus. Adapter +drivers are in the ``drivers/i2c/busses/`` subdirectory. -For a given configuration, you will need a driver for your I2C bus, and -drivers for your I2C devices (usually one driver for each device). +An **algorithm** contains general code that can be used to implement a +whole class of I2C adapters. Each specific adapter driver either depends on +one algorithm driver, or includes its own implementation. + +A **slave** chip is a node that responds to communications when addressed +by the master. In Linux it is called a **client**. Client drivers are kept +in a directory specific to the feature they provide, for example +``drivers/media/gpio/`` for GPIO expanders and ``drivers/media/i2c/`` for +video-related chips. + +For the example configuration in figure, you will need a driver for your +I2C adapter, and drivers for your I2C devices (usually one driver for each +device). -- 2.24.1