[U-Boot] [RFC] How to get "#address-cells" in U-Boot?

[Simon Glass]

Hi Masahiro,

On 17 November 2014 11:02, Masahiro Yamada <yamada.m at jp.panasonic.com> wrote:
>
> Hi.
>
> >
> > Another question.
> >
> > Can U-boot handle the address transformation?
> >
> > If the upper "bus" node has "ranges" property,
> > it must also be checked to get the correct base address, I think.
>
>
> I take this question back too.
> Sorry for noise.

OK no problem! Also see fdt_address_cells() and fdt_size_cells() which
are in libfdt now.

- Simon

>
>
>
> >
> > On Mon, 17 Nov 2014 19:38:41 +0900
> > Masahiro Yamada <yamada.m at jp.panasonic.com> wrote:
> >
> > > Hi.
> > >
> > >
> > > I want to decode the base address of device nodes of my device trees.
> > >
> > > For example, drivers/serial/ns16550.c uses fdtdec_get_addr() function
> > > to decode the "reg" property, but it is not very nice because
> > > it does not check "#address-cells".
> > >
> > > Precisely, we need to check the parent node to get "#address-cells".
> > > (If the parent does not have it, we need to search for it towards the root node.)
> > >
> > >
> > > I am looking for something like of_n_addr_cells() and of_n_size_cells() functions
> > > of Linux Kernel.
> > >
> > >
> > > I don't think it is feasible in U-Boot because
> > > U-Boot handles device tree blobs as they are (as flattened binaries).
> > >
> > > If we want to get properties of the parenet node, we must parse the DTB from the
> > > beginning.  Yes, U-Boot actually parses the same DTB over and over again.
> > >
> > > Any advice?   Import drivers/of/* from Linux??
> > >
> > >
> > >
> > > Simon, do you have any good idea to solve this problem by DM?
> > > For example, add "address_cells" and "size_cells" members to struct udevice
> > > and then  modify drivers/core/simple-bus.c to parse "#address-cells" and "#size-cells"
> > > and pass them to children.
> > >
> > >
> >
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>