[PATCH 00/23] RFC: exynos multiplatform support

[Thierry Reding]

On Thu, Mar 07, 2013 at 03:02:46AM +0000, Arnd Bergmann wrote:
> On Wednesday 06 March 2013, Thierry Reding wrote:
> > > Option 2 would probably come down to having a trivial MFD driver exposing
> > > a regmap. You can probably reuse drivers/mfd/syscon.c for this and make
> > > the node compatible with "syscon" to designate the clock registers as
> > > a system-wide resource, making the other device nodes register-less.
> > 
> > I think option 2 is the standard method if one hardware block provides
> > several logical devices. I find it to be a pretty nice solution to this
> > problem. We also have precedent in the PWM subsystem. The TWL chips for
> > instance use it to create a platform device which is later driven by a
> > PWM driver.
> 
> One difference though is that the TWL chip is a heterogenous MFD that has
> a lot of different sub-devices, where in case of Exynos the timer device
> has a set of identical units, each of which can be used either as a PWM or
> as a clocksource or other timer.

I didn't know that. However I still making this an MFD driver is a good
fit because it'll move the logic of defining the mode of each unit is
kept in a parent driver which can instantiate the proper child devices
for the corresponding subsystems.

One big disadvantage of this approach is that if this is continued there
is a risk that MFD will turn into a dump for all kinds of devices that
provide more than a single service.

So if people prefer option 3 I'm fine with it as well.

Thierry
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