Re: Point-to-point bus in device tree

Stephen Warren
2012-04-05T19:23:50Z

On 04/05/2012 12:15 PM, David Brown wrote:
> Some MSM SoCs have a small serial-type "bus" that is used to
> communicate with the PMIC devices. This interface is always
> point-to-point. I'm doing a device-tree conversion of the driver that
> Ken Heitke posted last year <https://lkml.org/lkml/2011/2/17/503>.
>
> A naive conversion to device tree, would result in something like
> this:
>
> qcom,ssbi@500000 {
> compatible = "qcom,ssbi";
> reg = <0x500000 0x1000>;
> qcom,controller-type = "ssbi";
>
> qcom,pmic8058@0 {
> reg = <0x0 0x01>;
> ...
> }
> }
>
> There would end up being an extraneous register for the device on the
> other end (there are no addresses), and there would need to be code in
> the ssbi driver to traverse this small tree to find these nodes.

Isn't that extra code simply:

of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);

That seems like pretty low overhead.