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

[Masahiro Yamada]

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.



Best Regards
Masahiro Yamada