On Wed, Dec 14, 2016 at 12:40 PM, Russell King - ARM Linux
[off-list ref] wrote:

Looking at this more, it's a SPI driver, presumably because the first
case where it appeared was on a SPI bus.

However, it's not a SPI device as such, it's a piece of standard,
general purpose logic that's been around for many years, pre-dating
the SPI bus.

Indeed.

I think a much more sensible approach would be to turn the GPIO side
of the 74x164 driver into a library, which can be re-used by multiple
bus-specific drivers - one for SPI which allows it to be used in its
current form, one for our platform bus which takes the GPIO lines for
the data, clock and clear signals.

I also don't see why they shouldn't use the same compatible - they're
the same _device_ at the end of the day, just wired up differently.
It makes the binding documentation a little fun wrt what are required
and optional properties, but nothing that shouldn't be too difficult.

I agree on both accounts.

Sorry for not seeing this in the first place, I was well aware that this
is a standard component and may be connected in a myriad of ways,
so I should have known better :(

Yours,
Linus Walleij