of: populate of_root node if bootloader doesn't

Arch maintainers, please ack/review patches.

This is a resend of a series from Frank last year[1]. I worked in Rob's review comments to unconditionally call unflatten_device_tree() and fixup/audit calls to of_have_populated_dt() so that behavior doesn't change.

I need this series so I can add DT based tests in the clk framework. Either I can merge it through the clk tree once everyone is happy, or Rob can merge it through the DT tree and provide some branch so I can base clk patches on it.

Changes from v3 (https://lore.kernel.org/r/[email protected]):
* Made OF_UNITTEST depend on OF_EARLY_FLATREE
* Made OF_EARLY_FLATREE depend on absence of arches that don't call unflatten_device_tree()
* Added of_ prefix to dtb_ prefixed KUnit tests
* Picked up tags

Changes from v2 (https://lore.kernel.org/r/[email protected]):
* Reorder patches to have OF changes largely first
* No longer modify initial_boot_params if ACPI=y
* Put arm64 patch back to v1

Changes from v1 (https://lore.kernel.org/r/[email protected]):
* x86 patch included
* arm64 knocks out initial dtb if acpi is in use
* keep Kconfig hidden but def_bool enabled otherwise

Changes from Frank's series[1]:
* Add a DTB loaded kunit test
* Make of_have_populated_dt() return false if the DTB isn't from the bootloader
* Architecture calls made unconditional so that a root node is always made

Frank Rowand (2):
of: Create of_root if no dtb provided by firmware
of: unittest: treat missing of_root as error instead of fixing up

Stephen Boyd (5):
of: Always unflatten in unflatten_and_copy_device_tree()
um: Unconditionally call unflatten_device_tree() x86/of: Unconditionally call unflatten_and_copy_device_tree()
arm64: Unconditionally call unflatten_device_tree()
of: Add KUnit test to confirm DTB is loaded

 arch/arm64/kernel/setup.c    |  3 +-
 arch/um/kernel/dtb.c         | 14 ++++----
 arch/x86/kernel/devicetree.c | 24 +++++++-------
 drivers/of/.kunitconfig      |  3 ++
 drivers/of/Kconfig           | 14 ++++++--
 drivers/of/Makefile          |  4 ++-
 drivers/of/empty_root.dts    |  6 ++++
 drivers/of/fdt.c             | 64 +++++++++++++++++++++++++++---------
 drivers/of/of_test.c         | 57 ++++++++++++++++++++++++++++++++
 drivers/of/platform.c        |  3 --
 drivers/of/unittest.c        | 16 +++------
 include/linux/of.h           | 25 ++++++++------
 12 files changed, 168 insertions(+), 65 deletions(-)
 create mode 100644 drivers/of/.kunitconfig
 create mode 100644 drivers/of/empty_root.dts
 create mode 100644 drivers/of/of_test.c

[1] https://lore.kernel.org/r/[email protected]

base-commit: 6613476e225e090cc9aad49be7fa504e290dd33d

https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/
https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git