port-arm/59680: Add Device Tree Support for armv5

[yuri.honegger%icloud.com@localhost]

>Number:         59680
>Category:       port-arm
>Synopsis:       Add Device Tree Support for armv5
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    port-arm-maintainer
>State:          open
>Class:          change-request
>Submitter-Id:   net
>Arrival-Date:   Tue Sep 30 19:00:01 +0000 2025
>Originator:     Yuri Honegger
>Release:        11.99.2
>Organization:
>Environment:
>Description:
There is no support for device trees (FDT) on armv5 boards. I've been working on adding support and have been told to open a bug here.

See: https://mail-index.netbsd.org/port-arm/2025/09/27/msg009420.html
>How-To-Repeat:

>Fix:
I've prepared the following patch:

github link: https://github.com/NetBSD/src/compare/trunk...recursivetree:netbsd-src:armv5-fdt-upstreamable-v2

patch: https://github.com/NetBSD/src/compare/trunk...recursivetree:netbsd-src:armv5-fdt-upstreamable-v2.patch

There are two parts to it:
- the general changes required to boot an armv5 CPU using device trees. This adds a GENERIC_V5 configuration, the MMU initialization code and some ifdefs around platform-specific stuff.
- device tree based drivers for the NXP i.MX23 SOC on the olinuxino board. I've used this board for development because it is an armv5 board already supported by NetBSD. For now, I've only converted the absolute minimum to boot NetBSD (interrupt and timer drivers).