[PATCH v1 1/2] dt-bindings: soc: samsung: usi: allow 64-bit address space

[Sam Protsenko]

On Wed, Jul 23, 2025 at 3:21 AM Ivaylo Ivanov
<ivo.ivanov.ivanov1 at gmail.com> wrote:
>
> On 7/23/25 11:15, Krzysztof Kozlowski wrote:
> > On Tue, Jul 22, 2025 at 03:10:36PM +0300, Ivaylo Ivanov wrote:
> >> Some device trees, like the exynos2200 one, configure the root node
> >> with #address-cells and #size-cells set to 2. However, the usi binding
> >> expects 32 bit address space only. Allow these determining properties to
> > So if USI expects 32 bit, then why do we allow 64?
> >
> > Switching this to 2 means you use 64-bit addressing for children
>
> I don't, but the main point was to avoid defining ranges for every single usi
> node, because they are a lot.
>

If all MMIO addresses in your SoC are 32-bit (they probably are), I
think it'd be neater to just make the entire "soc" bus 32-bit (so both
address and size cells = <1>), and map it to the root node's address
space with "ranges", like this:

    soc: soc at 0 {
        compatible = "simple-bus";
        #address-cells = <1>;
        #size-cells = <1>;
        ranges = <0x0 0x0 0x0 0x20000000>;
        ...

That's how it's done in exynos850 and gs101 dts for example. This way
you could drop all those extra "reg = <0x0 ...>" in the child nodes,
also avoid declaring "ranges" arrays in each USI node (just "ranges;"
would be enough), and this patch won't be needed. Maybe I'm missing
some details though?

> Best regards,
> Ivaylo
>
> >  and
> > allowing DMA for >32 bit. This should be the true reason - what is the
> > address space and DMA range for children?
> >
> > Best regards,
> > Krzysztof
> >
>