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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 E42FDC433E2 for ; Tue, 9 Jun 2020 15:01:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C2F3B2078D for ; Tue, 9 Jun 2020 15:01:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=walle.cc header.i=@walle.cc header.b="euAsn1+1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730539AbgFIPBZ (ORCPT ); Tue, 9 Jun 2020 11:01:25 -0400 Received: from ssl.serverraum.org ([176.9.125.105]:41115 "EHLO ssl.serverraum.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725948AbgFIPBX (ORCPT ); Tue, 9 Jun 2020 11:01:23 -0400 Received: from ssl.serverraum.org (web.serverraum.org [172.16.0.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ssl.serverraum.org (Postfix) with ESMTPSA id ECD3222F2D; Tue, 9 Jun 2020 17:01:17 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=walle.cc; s=mail2016061301; t=1591714878; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=aMjIHhTy6QW0P3MAj5LndzKCaO3yMkaVaezROboWYDQ=; b=euAsn1+18dDVaj3N75vATYwEPsegHDppC2VkD83JeqzT2R996iBd9IREmPEKKWtU3l6Y87 FIevxYAgjKLBLJOEfvarLgLrdMoq2oGSqGMdyVuvbdXSk4KVSd+kZBW/cn+mGMxySwB626 jCO4U5VjZWc1OyJMGDZeHKyJ7fca1Ik= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 09 Jun 2020 17:01:17 +0200 From: Michael Walle To: Mark Brown Cc: Lee Jones , Andy Shevchenko , Ranjani Sridharan , david.m.ertman@intel.com, shiraz.saleem@intel.com, Rob Herring , "open list:GPIO SUBSYSTEM" , devicetree , Linux Kernel Mailing List , linux-hwmon@vger.kernel.org, linux-pwm@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-arm Mailing List , Linus Walleij , Bartosz Golaszewski , Jean Delvare , Guenter Roeck , Thierry Reding , =?UTF-8?Q?Uwe_Kleine-K?= =?UTF-8?Q?=C3=B6nig?= , Wim Van Sebroeck , Shawn Guo , Li Yang , Thomas Gleixner , Jason Cooper , Marc Zyngier , Greg Kroah-Hartman , Andy Shevchenko Subject: Re: [PATCH v4 02/11] mfd: Add support for Kontron sl28cpld management controller In-Reply-To: <20200609144201.GK4583@sirena.org.uk> References: <20200606114645.GB2055@sirena.org.uk> <20200608082827.GB3567@dell> <7d7feb374cbf5a587dc1ce65fc3ad672@walle.cc> <20200608185651.GD4106@dell> <32231f26f7028d62aeda8fdb3364faf1@walle.cc> <20200609064735.GH4106@dell> <32287ac0488f7cbd5a7d1259c284e554@walle.cc> <20200609144201.GK4583@sirena.org.uk> User-Agent: Roundcube Webmail/1.4.4 Message-ID: X-Sender: michael@walle.cc Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Am 2020-06-09 16:42, schrieb Mark Brown: > On Tue, Jun 09, 2020 at 04:38:31PM +0200, Michael Walle wrote: > >> mfd-device@10 { >> compatible = "simple-regmap", "simple-mfd"; >> reg = <10>; >> regmap,reg-bits = <8>; >> regmap,val-bits = <8>; >> sub-device@0 { >> compatible = "vendor,sub-device0"; >> reg = <0>; >> }; > > A DT binding like this is not a good idea, encoding the details of the > register map into the DT binding makes it an ABI which is begging for > trouble. I'd also suggest that any device using a generic driver like > this should have a specific compatible string for the device so we can > go back and add quirks later if we need them. Like in the spidev case, yes. But OTOH if I _just_ encode the parameters for the regmap a MFD, Lee don't agree because its just a shim. So either way I seem to be stuck here. Where should I put the code to create an i2c driver, init a regmap and populate its childen? -michael > >> ... >> }; >> >> Or if you just want the regmap: >> >> &soc { >> regmap: regmap@fff0000 { >> compatible = "simple-regmap"; >> reg = <0xfff0000>; >> regmap,reg-bits = <16>; >> regmap,val-bits = <32>; >> }; >> >> enet-which-needs-syscon-too@1000000 { >> vendor,ctrl-regmap = <®map>; >> }; >> }; >> >> Similar to the current syscon (which is MMIO only..). >> >> -michael >> >> > >> > I can't think of any reasons why not, off the top of my head. >> > >> > Does Regmap only deal with shared accesses from multiple devices >> > accessing a single register map, or can it also handle multiple >> > devices communicating over a single I2C channel? >> > >> > One for Mark perhaps. >> > >> > > > The issues I wish to resolve using 'simple-mfd' are when sub-devices >> > > > register maps overlap and intertwine. >> > >> > [...] >> > >> > > > > > > What do these bits configure? >> > > > > >> > > > > - hardware strappings which have to be there before the board powers >> > > > > up, >> > > > > like clocking mode for different SerDes settings >> > > > > - "keep-in-reset" bits for onboard peripherals if you want to save >> > > > > power >> > > > > - disable watchdog bits (there is a watchdog which is active right >> > > > > from >> > > > > the start and supervises the bootloader start and switches to >> > > > > failsafe >> > > > > mode if it wasn't successfully started) >> > > > > - special boot modes, like eMMC, etc. >> > > > > >> > > > > Think of it as a 16bit configuration word. >> > > > >> > > > And you wish for users to be able to view these at run-time? >> > > >> > > And esp. change them. >> > > >> > > > Can they adapt any of them on-the-fly or will the be RO? >> > > >> > > They are R/W but only will only affect the board behavior after a >> > > reset. >> > >> > I see. Makes sense. This is board controller territory. Perhaps >> > suitable for inclusion into drivers/soc or drivers/platform. -- -michael