dt: build overlays

Hi,

This patchset makes necessary changes to the kernel to add support for building overlays (%.dtbo) and the required fdtoverlay tool. This also builds static_test.dtb using most of the existing overlay tests present in drivers/of/unittest-data/ for better test coverage.

Note that in order for anyone to test this stuff, you need to manually run the ./update-dtc-source.sh script once to fetch the necessary changes from the external DTC project (i.e. fdtoverlay.c and this[1] patch).

I have tested this patchset for static and runtime testing (on Hikey board) and no issues were reported.

V7:
- Add a comment in scripts/dtc/Makefile
- Add Ack from Masahiro for patch 4/6.
- Drop word "merge" from commit log of 2/6.
- Split apply_static_overlay, static_test.dtb, and static_base.dts into two parts to handle overlay_base.dts and testcases.dts separately.

V6:
- Create separate rules for dtbo-s and separate entries in .gitignore in 4/6 (Masahiro).
- A new file layout for handling all overlays for existing and new tests 5/6 (Frank).
- Include overlay.dts as well now in 6/6 (Frank).

V5:

- Don't reuse DTC_SOURCE for fdtoverlay.c in patch 1/5 (Frank).

- Update .gitignore and scripts/Makefile.dtbinst, drop dtbo-y syntax and DTC_FLAGS += -@ in patch 4/5 (Masahiro).

- Remove the intermediate dtb, rename output to static_test.dtb, don't use overlay.dtb and overlay_base.dtb for static builds, improved layout/comments in Makefile for patch 5/5 (Frank).

--
Viresh

[1] https://github.com/dgibson/dtc/commit/163f0469bf2ed8b2fe5aa15bc796b93c70243ddc
[2] https://lore.kernel.org/lkml/[email protected]/

Viresh Kumar (6):
scripts: dtc: Fetch fdtoverlay.c from external DTC project
scripts: dtc: Build fdtoverlay tool
scripts: dtc: Remove the unused fdtdump.c file
kbuild: Add support to build overlays (%.dtbo)
of: unittest: Create overlay_common.dtsi and testcases_common.dtsi
of: unittest: Statically apply overlays using fdtoverlay

 .gitignore                                    |   1 +
 Makefile                                      |   5 +-
 drivers/of/unittest-data/Makefile             |  56 ++++++
 drivers/of/unittest-data/overlay_base.dts     |  90 +---------
 drivers/of/unittest-data/overlay_common.dtsi  |  91 ++++++++++
 drivers/of/unittest-data/static_base_1.dts    |   4 +
 drivers/of/unittest-data/static_base_2.dts    |   4 +
 drivers/of/unittest-data/testcases.dts        |  18 +-
 .../of/unittest-data/testcases_common.dtsi    |  19 ++
 .../of/unittest-data/tests-interrupts.dtsi    |   7 -
 scripts/Makefile.dtbinst                      |   3 +
 scripts/Makefile.lib                          |   5 +
 scripts/dtc/Makefile                          |   8 +-
 scripts/dtc/fdtdump.c                         | 163 ------------------
 scripts/dtc/update-dtc-source.sh              |   3 +-
 15 files changed, 204 insertions(+), 273 deletions(-)
 create mode 100644 drivers/of/unittest-data/overlay_common.dtsi
 create mode 100644 drivers/of/unittest-data/static_base_1.dts
 create mode 100644 drivers/of/unittest-data/static_base_2.dts
 create mode 100644 drivers/of/unittest-data/testcases_common.dtsi
 delete mode 100644 scripts/dtc/fdtdump.c

base-commit: 6ee1d745b7c9fd573fba142a2efdad76a9f1cb04

2.25.0.rc1.19.g042ed3e048af