From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753549AbaLIIYc (ORCPT ); Tue, 9 Dec 2014 03:24:32 -0500 Received: from mout.kundenserver.de ([212.227.126.187]:54930 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751487AbaLIIYa (ORCPT ); Tue, 9 Dec 2014 03:24:30 -0500 From: Arnd Bergmann To: Flora Fu Cc: Matthias Brugger , linux-arm-kernel@lists.infradead.org, Rob Herring , Samuel Ortiz , Lee Jones , Liam Girdwood , Mark Brown , arm@kernel.org, Mark Rutland , devicetree@vger.kernel.org, Russell King , srv_heupstream@mediatek.com, Pawel Moll , Ian Campbell , linux-kernel@vger.kernel.org, HenryC Chen , Menghui Lin , Olof Johansson , Sascha Hauer , Kumar Gala , Grant Likely , Yingjoe Chen , Eddie Huang , Dongdong Cheng Subject: Re: [PATCH v3 1/8] soc: mediatek: Add PMIC wrapper for MT8135 and MT6397 SoC Date: Tue, 09 Dec 2014 09:23:18 +0100 Message-ID: <2248330.M654Toyebg@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1418091337.5663.9.camel@mtksdaap41> References: <1417752479-4749-1-git-send-email-flora.fu@mediatek.com> <2751641.o51TuZRl88@wuerfel> <1418091337.5663.9.camel@mtksdaap41> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:V8bdBfzjvrGEk4k/cfVjEGD2Vutx7fbqV8e6v6tWaRD/u/a3G7u Y9ZISUceHrgsdxJLex+sb5ScaiHmQA+RN5cbC8BDkkOnk7FTtRKrNesKSQ5umx1rWhLIbvE /ofkoawZ+b25VawRqCe6YEX8CtBD0Qn98iGrYAZNP/gmrScGCctfMe3MjM0vgVSpCb6HHx/ Va1N08Jjy5hmOI86NRJdQ== X-UI-Out-Filterresults: notjunk:1; Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 09 December 2014 10:15:37 Flora Fu wrote: > Hi, Arnd, > > On Fri, 2014-12-05 at 11:13 +0100, Arnd Bergmann wrote: > > On Friday 05 December 2014 12:07:52 Flora Fu wrote: > > > Add PMIC wrapper of MT8135 to access MT6397 MFD. > > > > > > Signed-off-by: Flora Fu > > > > > > > Please explain what a PMIC wrapper is and why you need one for MT8135. > > I don't understand the purpose of this code at all. Is this just another > > way of accessing the MT6397 when not using i2c or spi like other > > PMIC drivers do? > > > > Yes, MT8135 uses a proprietary hardware to communicate with MT6397. > The hardware is called PMIC Wrapper or PWRAP. > Since it is not standard i2c or spi protocols, a soc related software > driver is implemented to handle access protocols in AP side. > > +-----------------+ +---------------+ > | | | | > | Mediatek AP SoC | | | > | (ex. MT8135) | | MT6397 | > | | | | > | +--------+ | (SPI bus) | +--------+ | > | | | |-----------| | | | > | | PMIC | |-----------| | PMIC | | > | | Wrapper| |-----------| | Wrapper| | > | | | |-----------| | | | > | +--------+ | | +--------+ | > | | | | > +-----------------+ +---------------+ > I think we have had a similar case recently where a controller wasn't actually using I2C, but the sofware protocol was close enough so we decided to make it appear as i2c in Linux. Would that work for you, i.e. register the pmic wrapper as a fake spi master driver in drivers/spi/ and register the rtc/regulator/codec as SPI clients from DT? Arnd