Re: [PATCHv1] rtc: bcm-iproc: Add support for Broadcom iproc rtc

[Arun Ramamurthy]

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
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