regmap-mmio and paged registers

Mark Brown broonie at
Wed Dec 16 03:38:52 PST 2015

On Wed, Dec 09, 2015 at 11:26:13PM +0100, Alexandre Belloni wrote:
> On 09/12/2015 at 22:10:36 +0000, Mark Brown wrote :

> > Honestly looking at the register I'm not even convinced it is a paged
> > regmap, it looks more like a mailbox for communication with a
> > coprocessor than anything else (the fact that the selector is named PID,
> > the fact that the bitfields include CMD...).  Are you sure that it's a
> > good idea to represent this as a regmap at all?

> Yeah, I was probably not clear enough but the regmap actually covers the
> whole PMC range and include that particular register. We have to do that
> because this range is used by multiple drivers.

I don't see how that follows?  You can layer anything you like on top of
a regmap.

> This register, PMC_PCR is also used by multiple drivers so it is
> important to properly lock between the page selection and the following
> read or write.

regmaps aren't the only way of sharing access to something - like I say
there's the mailbox API too.
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