On Wed, May 08, 2013 at 04:50:22PM +0200, Arnd Bergmann wrote:

quoted

In many cases a single syconf register contains bits related to multiple
devices, and therefore it need to be shared across multiple drivers at
bit level. The same IP block can have different syscon mappings on
different SOCs.

My feeling is that syscon is the wrong place for this functionality,
since regmap already handles (some of?) these issues. If you need
additional synchronization, it's probably best to extend regmap
as needed so other code besides syscon can take advantage of that
as well.

This sounds like regmap_update_bits() ought to be all that's needed.