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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 4AE1AC433E0 for ; Thu, 11 Mar 2021 10:18:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DD65864FC0 for ; Thu, 11 Mar 2021 10:18:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232224AbhCKKRc (ORCPT ); Thu, 11 Mar 2021 05:17:32 -0500 Received: from mout.kundenserver.de ([212.227.17.13]:37371 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232246AbhCKKRY (ORCPT ); Thu, 11 Mar 2021 05:17:24 -0500 Received: from [192.168.1.155] ([77.4.9.157]) by mrelayeu.kundenserver.de (mreue109 [212.227.15.183]) with ESMTPSA (Nemesis) id 1N2V8T-1ljcBP3SEp-013tag; Thu, 11 Mar 2021 11:17:16 +0100 Subject: Re: [RFC PATCH 07/12] gpio: amd-fch: add oftree probing support To: Linus Walleij , "Enrico Weigelt, metux IT consult" Cc: "linux-kernel@vger.kernel.org" , "Rafael J. Wysocki" , Bartosz Golaszewski , Rob Herring , Frank Rowand , Pantelis Antoniou , "open list:GPIO SUBSYSTEM" , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" References: <20210208222203.22335-1-info@metux.net> <20210208222203.22335-8-info@metux.net> From: "Enrico Weigelt, metux IT consult" Message-ID: Date: Thu, 11 Mar 2021 11:17:15 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: tl Content-Transfer-Encoding: 8bit X-Provags-ID: V03:K1:Da5Wubz3qht31qNBK8msWmU8qQAtD6bVMmtMsHo+GTkYRtzJd6S 7Ol0A9BMSURMyP2Yu/miLKao45Xa13V5Kb3BWeOh7wqOEc9fB8UxguLXHW+rTwNElnvCzcu +qpaJRemDCDtrAaZOZQ5+Gu/dhQwzmDA7FyAhxa7HUfrSGX1sP4JjxG5OioUUIq6gZE/v1R 6pjZgNAue4tF/Ksqv6lMg== X-UI-Out-Filterresults: notjunk:1;V03:K0:dWRgG5/anZU=:mP3bijunZIqP6TdOJBFCjd lHZxNgzlXuBEB0VIBDHth7kTL6LMYPRRTQ52DA93xCrbGNJNi4kLNwAdPZ6PcgZPAj0TS1d8x h+ht1TtF3bSY7yGmoTNlC0fSTlEtSH+Z6kxjkSsxPYp1x2nP9dMcDYJxGPGoZEPM8FC0u+G6f NFIkuE8riEmyELmYA5E+/dp5cUTyS3L/m0fVi8Ot/6IbEQA3xS+ynsf3TfcrpUS9J/B9T2lwO NJW87RP3heEWl/BJOoASlUdkcpObwHGg1QfSGsazWc5rDoIyEhr3utt5bqyVvhGwmBqeLjM9b vIXZUExk23HQDuZu58Po5Ht0rzNl8nOMMGp3jslfcTbrqQTl9yymho/pX0hGnjSkrRsPe0xOU dIUcCuFU0RD1oPHjrquHUIc+5etomd9WggZjqUamxsNng/EbwXCRoVWZzKMyq Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01.03.21 15:51, Linus Walleij wrote: Hi, > I don't know what the idea is with this but register are not normally defined > in the DTS files. The registers are determined from the compatible value. The idea is basically replacing the pdata struct by oftree node. (subsequent patches in this queue use this by doing the board setup via compiled-in dtb, instead of the currently hardcoded tables). On these SoCs, the gpio setup is a little bit more complex than just having a fixed range of registers (one per pin): the actual meaning depends und Soc model and board type - some regs aren't even gpios. (I'm still in progress of RE'ing the bios blob, to find out more, eg. pinmux setups, etc). Writing to the wrong regs can cause weird effects (actually not even sure whether it could lead to damage) In essence: only a specific subset of the register range can be used for GPIOs - the others shouldn't ever be touched. And this specific subset is soc/board specific. --mtx -- --- Hinweis: unverschlüsselte E-Mails können leicht abgehört und manipuliert werden ! Für eine vertrauliche Kommunikation senden Sie bitte ihren GPG/PGP-Schlüssel zu. --- Enrico Weigelt, metux IT consult Free software and Linux embedded engineering info@metux.net -- +49-151-27565287