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

[Masahiro Yamada]

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.
> 


I almost solved this problem by myself.

We can get the properties of the parent node with

((struct udevice *)dev)->parent->of_offset



Sorry for noise.