From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Wahren Subject: Re: [PATCH 1/2] DT: add binding for mxs regulator Date: Mon, 29 Sep 2014 15:10:07 +0200 Message-ID: <54295A2F.3070700@i2se.com> References: <1411779588-22031-1-git-send-email-stefan.wahren@i2se.com> <1411779588-22031-2-git-send-email-stefan.wahren@i2se.com> <20140929110919.GB2432@leverpostej> <54294832.8000702@i2se.com> <20140929124137.GD2432@leverpostej> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140929124137.GD2432@leverpostej> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mark Rutland Cc: "lgirdwood-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" , "broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , "shawn.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , "robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , Pawel Moll , "ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org" , "galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org" , "festevam-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org" List-Id: devicetree@vger.kernel.org Hi, Am 29.09.2014 um 14:41 schrieb Mark Rutland: > Well, the simple-bus will cause the children to be probed. But it looks > like you care about properties of the parent. I don't think that > simple-bus is appropriate because it's not being handled as a > transparent bridge from the PoV of the children. actually i need the address of the power status register. In this version i get the base address from the parent node add an offset. Do you prefer to define the address of the power status register like a second address cell: reg_vddd: regulator@80044040 { reg = <0x80044040 0x10 0x800440c0 0x01>; ... }; or do i need special properties like this: reg_vddd: regulator@80044040 { reg = <0x80044040 0x10>; fsl,mxs-status-reg = <0x800440c0>; ... }; >> Do we need a extra driver? > Perhaps, but it's relatively simple to match on a compatible string and > probe children if you just wantto start small for now. Okay. Would be great if someone has a good example. At first, i thought of power/anatop. > >>>> +- #address-cells: Number of cells required to define regulator register, >>>> + must be 1 >>>> +- #size-cells: Number of cells required to define register size, must be 1 >>> Why must this be the case, given that the child node expects an absolute >>> physical address? >> I need a property to define the control register for the regulators >> without defining vendor specific properties like "fsl,mxs-control-reg" >> or something. > You misunderstand me. I was querying the "must be 1" rather than the > proeprties themselves. > >>> What's wrong with #address-cells = <2>, for example? >> Nothing > Then we shouldn't specify "must be 1", no? Right, must be at least 1. >>>> +- reg: Absolute physical address and size of the register set for the device >>> Why is this here _and_ in the child node(s)? >> The parent of the power node is also a simple bus. I use this to >> calculate the power status register per offset. >> >>> What is the difference between this node and its children? >> The parent node represent the power sub system and the regulators are >> part of this sub system. >> >>> Can there be more than one sub-node? >> In the i.MX28 are at least 4 voltage regulators, 1 current regulator and >> many more. At first, the driver should implement only 3 voltage >> regulators (vddd, vdda, vddio). > Ok. > > I think you need a binding for the power subsystem, and a trivial driver > that can match on that and probe the child regulators. Are there > components other than voltage or current regulators in the sub system? Yes, according to the reference manual there is a dc-dc converter, a battery charger, battery monitor, ... In short a lot of developing time ;-) > Mark. Best regards Stefan -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html