[PATCH 0/3] pmdomain: core: add support for domain hierarchies in DT

Currently, PM domains can only support hierarchy for simple
providers (e.g. ones with #power-domain-cells = 0).

Add support for oncell providers as well by adding a new property
`power-domains-child-ids` to describe the parent/child relationship.

This idea was previously discussed on the arm-scmi mailing list[1]
where this approach was proposed by Ulf, and then an initial RFC[2]
implementation was made.  From there, it was suggested by Rob[3] to
use a nexus node map instead, which led to several more versions
attempting to implement that, culminating in v5[4], where Rob and
Geert then had second thoughts about the power-domain-map approach.

Therefore, I've gone back to the approach in the initial RFC[2] to use
the child-ids approach.

Changes compared to initial RFC[2]
- dropped RFC
- rewrote the parse/add function to use iterators/helpers from of.h
- add a remove function for cleanup
- use child domain language instead of subdomain

[1] https://lore.kernel.org/arm-scmi/CAPDyKFo_P129sVirHHYjOQT+QUmpymcRJme9obzKJeRgO7B-1A@mail.gmail.com/ (local)
[2] https://lore.kernel.org/all/20250528-pmdomain-hierarchy-onecell-v1-1-851780700c68@baylibre.com/ (local)
[3] https://lore.kernel.org/all/20250528203532.GA704342-robh@kernel.org/ (local)
[4] https://lore.kernel.org/r/20260122-pmdomain-hierarchy-onecell-v5-0-76855ec856bd@baylibre.com (local)

Signed-off-by: Kevin Hilman (TI) <khilman@baylibre.com>
---
Kevin Hilman (TI) (3):
      dt-bindings: power: Add power-domains-child-ids property
      pmdomain: core: add support for power-domains-child-ids
      pmdomain: arm_scmi: add support for domain hierarchies

 Documentation/devicetree/bindings/power/power-domain.yaml |  35 ++++++++++++++++++++++++++++++++++
 drivers/pmdomain/arm/scmi_pm_domain.c                     |  14 +++++++++++++-
 drivers/pmdomain/core.c                                   | 169 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/pm_domain.h                                 |  16 ++++++++++++++++
 4 files changed, 233 insertions(+), 1 deletion(-)
---
base-commit: f7b88edb52c8dd01b7e576390d658ae6eef0e134
change-id: 20260310-topic-lpm-pmdomain-child-ids-e3d57ae57040

Best regards,
--  
Kevin Hilman (TI) [off-list ref]