Re: [PATCHv3] gpio-generic: add support for device tree probing

[Jamie Iles <jamie-wmLquQDDieKakBO8gow8eQ@public.gmane.org>]

On Sat, Jul 30, 2011 at 09:06:11PM -0600, Grant Likely wrote:
> On Fri, Jul 29, 2011 at 05:49:40PM +0100, Jamie Iles wrote:
> > On Fri, Jul 29, 2011 at 10:24:53AM -0600, Grant Likely wrote:
> > > I really do think that the compatible property can be dropped from the
> > > child nodes... although thinking further.  It doesn't have much value
> > > for specifying the exact controller, but maybe it should be used to
> > > specify the specific type of bank.  Right now the generic code uses a
> > > heuristic to figure out which set of accessor ops to use which strikes
> > > me as rather fragile.  I think it would be better to identify the
> > > major types of gpio controllers and name them.
> > 
> > I did think of doing this originally but I felt it could get a bit too 
> > unwieldy to describe all of the combinations (both in the compatible 
> > string and parsing code).  I guess in the driver we could have a list of 
> > templates that have a mask of the required registers for a given 
> > compatible string.
> 
> Yes, I was thinking along those lines.  The devil is in the
> implementation details of course.

OK.  I'll try prototyping something over the next couple of days but 
initially I was thinking something along the lines of a bitmask for all 
required registers for a given compatible string.  Then at probe time, 
for now just check that we have all of the required regoffset-* 
properties (and none that we shouldn't have).  We could still use the 
heuristics for working out the accessors for now but add accessors to 
the templates later if needed.

Jamie