From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arun Ramamurthy Subject: Re: [PATCHv1] rtc: bcm-iproc: Add support for Broadcom iproc rtc Date: Wed, 4 Mar 2015 14:40:13 -0800 Message-ID: <54F789CD.5030504@broadcom.com> References: <1418757750-3628-1-git-send-email-arun.ramamurthy@broadcom.com> <1603624.EMYvBCWhuM@wuerfel> <54DD2685.6020207@broadcom.com> <3699327.0G6ZNxn8QA@wuerfel> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <3699327.0G6ZNxn8QA@wuerfel> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Arnd Bergmann Cc: Ray Jui , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, a.zummo-BfzFCNDTiLLj+vYz1yj4TQ@public.gmane.org, sbranden-dY08KVG/lbpWk0Htik3J/w@public.gmane.org, pawel.moll-5wv7dgnIgG8@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org, Arun Ramamurthy , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, bcm-kernel-feedback-list-dY08KVG/lbpWk0Htik3J/w@public.gmane.org, galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, rtc-linux-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org List-Id: devicetree@vger.kernel.org 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. > >> On 14-12-17 06:31 AM, Arnd Bergmann wrote: >>> On Tuesday 16 December 2014 13:54:04 Arun Ramamurthy wrote: >>>> On 14-12-16 12:27 PM, Ray Jui wrote: >>>>> On 12/16/2014 12:19 PM, Arnd Bergmann wrote: >>>>>> >>>>>> It sounds like CRMU is some other unit aside from the RTC. Could this >>>>>> be something like a generic system controller? I think it should >>>>>> either have its own driver or use the syscon logic if that is what >>>>>> this is. >>>>>> >>>>> Giving that CRMU has scattered, miscellaneous control logic for multiple >>>>> different peripherals, it probably makes more sense to use the syscon >>>>> logic here. >>>>> >>>> Arnd, thanks for the feedback. If I was to write a separate driver for >>>> the CRMU, I would have to export certain functions and create an api >>>> that only this RTC driver would use. I am not sure that is efficient or >>>> required. What is your opinion? >>>> Would it be better if I use the syson api in my current driver and move >>>> the CRMU registers to separate syscon device tree entry? >>>> >>> >>> This is something that's normally up to the platform maintainers, depending >>> on what works best for a given SoC. If you have a control block that >>> wants to export the same high-level API for multiple drivers, that's >>> fine, but if literally every register does something different, a syscon >>> driver works best. >>> >>> It's also possible that some of the functions of the CRMU already have >>> abstractions, like system-reset, device-reset, regulator or clock support. >>> In that case, you can still use syscon but have the more other drivers >>> use that for accessing the registers. >>> >>> Arnd >>> >> -- >> 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 > -- 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