From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752301AbbCKUAU (ORCPT ); Wed, 11 Mar 2015 16:00:20 -0400 Received: from mail-gw1-out.broadcom.com ([216.31.210.62]:41140 "EHLO mail-gw1-out.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750820AbbCKUAQ (ORCPT ); Wed, 11 Mar 2015 16:00:16 -0400 X-IronPort-AV: E=Sophos;i="5.11,383,1422950400"; d="scan'208";a="59363226" Message-ID: <55009ED6.4050205@broadcom.com> Date: Wed, 11 Mar 2015 13:00:22 -0700 From: Arun Ramamurthy User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Arnd Bergmann CC: Ray Jui , , , , , , , , Arun Ramamurthy , , , , , , Subject: Re: [PATCHv1] rtc: bcm-iproc: Add support for Broadcom iproc rtc References: <1418757750-3628-1-git-send-email-arun.ramamurthy@broadcom.com> <2569223.1gDQjv8f8j@wuerfel> <54F78CF4.9040108@broadcom.com> <2216310.NqXA88JvvL@wuerfel> In-Reply-To: <2216310.NqXA88JvvL@wuerfel> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15-03-04 02:58 PM, Arnd Bergmann wrote: > On Wednesday 04 March 2015 14:53:40 Arun Ramamurthy wrote: >> On 15-03-04 02:50 PM, Arnd Bergmann wrote: >>> On Wednesday 04 March 2015 14:40:13 Arun Ramamurthy wrote: >>>> On 15-03-04 02:21 PM, Arnd Bergmann wrote: >>>>> On Thursday 12 February 2015 14:17:41 Arun Ramamurthy wrote: >>>>>> Hi Arnd >>>>>> >>>>>> My apologies for the late reply, I was moved to other work items. I >>>>>> wanted to get more clarification on the syscon issue so that I can >>>>>> submit the next patch set. If I understand correctly, you would like >>>>>> me to move the CRMU logic to a new driver under mfd/ and use the syscon >>>>>> api calls in my rtc driver? Thanks >>>>> >>>>> It depends a lot on what's in there, I can best advise you if you >>>>> have some form of register list. >>>>> >>>>> A common approach would be to not have a driver for the crmu at all, >>>>> but just mark it as syscon, and have the other drivers either reference >>>>> the syscon node through a phandle, or create them as childrem of >>>>> the syscon node. The latter case makes most sense if all uses of >>>>> the crmu have no other MMIO registers. >>>>> >>>> >>>> Thank you Arnd, I am going to follow the approach of adding a child node >>>> to the syscon node. Several other driver use other registers in the CRMU >>>> so I think the child node approach makes the most sense. >>> >>> Just to be sure we have the same understanding: of those other drivers, >>> do you think that they would use only CRMU registers, or could there >>> be drivers that have both CRMU as well as other MMIO registers? >>> >> The other drivers have both CRMU and other MMIO registers. So I thought >> they could also switch to using the syscon child nodes. >> > > No, in this case, better not use child nodes at all. When other platforms > use child nodes of a syscon, the common case is that they use the 'reg' > property to refer to syscon registers, which are in a different address > space from other MMIO, and you can't easily mix the two. > Arnd, this is the device tree entry that I would end up with and I plan to use syscon_regmap_lookup_by_phandle in the rtc driver. Does this look acceptable? rtc: iproc_rtc@0x03026000 { compatible = "brcm,iproc-rtc"; reg = <0x03026000 0xC>, iso_cell_syscon = <&crmu_iso_cell_control>; bbl_auth_syscon = <&crmu_bbl_auth> status = "okay"; crmu_iso_cell_control:crmu@0x0301C02C { compatible = "syscon"; reg = <0x0301C038 0x8> } crmu_bbl_auth:crmu@0x03024C74 { compatible = "syscon"; reg = <0x03024C74 0x8>; } Thanks > Arnd >