Re: [PATCH 00/55]: ARM: OMAP2+: PRCM move to drivers

[Tony Lindgren <tony@atomide.com>]

* Tero Kristo <t-kristo@ti.com> [140401 01:38]:
> On 04/01/2014 01:09 AM, Tony Lindgren wrote:
> >
> >We don't want to make access to these registers available without
> >proper frameworks as that will lead into misuse by various drivers.
> >And cleaning up that mess later in is a huge pain.
> 
> Currently, only thing that requires access to the register offsets
> is basically all the legacy clock data still in the kernel (when can
> we get rid of this, I have posted patches for it already?) and also
> the clockdomain / powerdomain data. I can work on getting
> clockdomain + powerdomain data to DT format if this would be
> preferred, then we can remove these data files also. Alternatively I
> can just move all these defines to the C files which actually use
> them.

With display support getting merged hopefully we can retry
dropping omap3 legacy booting as long as we get the missing
boards working.

I don't know how urgent of an issue the clock and power domains
are for the data compared to clocks and muxes. But if it allows us
to easily add support for new SoC variants, then yes it makes sense.

But in any case the defines should be private to the code claiming
the PRCM register area.

> So, basically you are proposing to add a regmap or regmap like API
> for the PRCM, which would provide access to a subset of registers
> only outside the PRCM driver? Some functions provided by PRCM spawn
> to multiple registers (like clocks), and the ranges have holes, and
> would require finetuning a register / bit level access map (some
> registers may contain functions for several drivers.)

Yeah something like that as that allows implementing the Linux
generic frameworks where the code really should be. And does not
require exporting tons of custom functions.
 
> >2. Have the core PRCM driver(s) claim some of the regmap ranges
> >
> >Some PRCM features can potentially be implemented using existing
> >Linux generic frameworks where possible for clocks, regulators, reset
> >drivers etc. That way you can keep the register defines for these
> >ranges private to the core PRCM driver(s). Ideally with no need
> >to add _any_ custom exported functions here.
> 
> There is separate work ongoing for reset driver, and for VC/VP,
> there has been some regulator related work. But yes, mostly this
> approach should be fine.

OK cool.
 
> >3. Have the other drivers claim some regmap ranges
> >
> >The register ranges that are clearly owned by some driver should
> >be claimed by those drivers. Then the defines for those registers
> >can stay private to that driver. Some drivers that can probably
> >own some PRCM ranges are clock drivers and voltage related drivers.
> 
> Yeah, this sounds reasonable.

OK

Tony