On Wed, Dec 12, 2007 at 03:47:32PM +0300, Anton Vorontsov wrote:
> On Tue, Dec 11, 2007 at 11:36:47AM +1100, David Gibson wrote:
> [...]
> > > > > OF device tree GPIOs bindings are similar to IRQs:
> > > > >
> > > > > node {
> > > > > gpios = <bank pin bank pin bank pin>;
> > > > > gpio-parent = <&par_io_controller>;
> > > > > };
> > > > >
> > > > > "bank pin" scheme is controller specific, so controllers that want
> > > > > to implement flat mappings or any other could do so.
> > > >
> > > > It might be safest to do as is done for interrupts, and not define the
> > > > internal format at all.
> > >
> > > This is how it is done already. Take a look into second and third patches:
> > >
> > > +static int par_io_xlate(struct device_node *np, int index)
> > > +{
> > > + return __of_parse_gpio_bank_pin(np, index, 32, num_par_io_ports);
> > > +}
> > > +
> > > +static struct of_gpio_chip of_gpio_chip = {
> > > + .xlate = par_io_xlate,
> > > +};
> > >
> > > __of_parse_gpio_bank_pin() is helper function, I just factored
> > > it out, because both QE and CPM2 using same format.
> > >
> > > But generally, controllers are encouraged to do their own xlates.
> > >
> > > Or am I missing the point?
> >
> > Right, but you are assuming a fixed size (2 cells?)
>
> Nope, of_get_gpio() doesn't assume that, but per-controller's .xlate()
> is free to assume (and check) that, right.
Ah, ok, I see. I think doing this without an explicit '#gpio-cells'
is not a great idea, though. It would be nice to be able to sanity
check the "gpio descriptors" without having to deduce the correct
format from the controller's "compatible" property.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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