[PATCH] of: support an enumerated-bus compatible value

[Grant Likely]

On Sun, Jul 1, 2012 at 1:36 PM, Rob Herring <robherring2 at gmail.com> wrote:
> On 06/28/2012 06:05 PM, Stephen Warren wrote:
>> From: Stephen Warren <swarren at nvidia.com>
>>
>> An "enumerated" bus is one that is not memory-mapped, hence hence
>> typically has #address-cells=1, and #size-cells=0. Such buses would be
>> used to group related non-memory-mapped nodes together, often just under
>> the top-level of the device tree. The ability to group nodes into a non-
>> memory-mapped subnode of the root is important, since if nodes exist to
>> describe multiple entities of the same type, the nodes will have the
>> same name, and hence require a unit address to differentiate them. It
>> doesn't make sense to assign bogus unit addresses from the CPU's own
>> address space for this purpose. An example:
>>
>>       regulators {
>>               compatible = "enumerated-bus";
>>               #address-cells = <1>;
>>               #size-cells = <0>;
>>
>>               regulator at 0 {
>>                       compatible = "regulator-fixed";
>>                       reg = <0>;
>>               };
>>
>>               regulator at 1 {
>>                       compatible = "regulator-fixed";
>>                       reg = <1>;
>>               };
>>       };
>>
>> Finally, because such buses are not memory-mapped, we avoid creating
>> any IO/memory resources for the device.
>
> This seems like a work-around to use reg instead of using cell-index
> (which is discouraged). reg in this case is really not a hardware
> description. Do you have an intended use or just trying to fix the error
> messages?

Besides; if they are enumerated, non-memory mapped devices, then is it
really appropriate to use platform_{device,driver}? I don't think it
is.

g.