[PATCH v2 0/3] MTD physmap: Adding reserved RAM support and fixing reserved_mem limitations

[Gregory CLEMENT <gregory.clement@bootlin.com>]

Hello,

While working on adding reserved RAM support to the MTD physmap
driver, I encountered a limitation in the kernel's reserved memory
support: although the Device Tree specification allows multiple reg
entries for a memory-region node, the kernel only processed the first
one. This limitation prevented proper support for reserved RAM regions
in MTD.

This series addresses both issues:

First, the reserved memory support is extended to fully support
multiple reg entries per memory-region node, ensuring compliance with
the Device Tree specification.

Then, with this foundation in place, the series updates the MTD
physmap driver to support reserved RAM regions. The DT bindings are
extended to allow memory-region phandles for RAM access, and the
physmap driver is modified to use these regions.

Gregory

Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
---
Changes in v2:

- Properly managed cases where register entries used by the memory
  region are out of order, particularly when one or more register
  entries are mixed with memory region entries in an other node.
- Used "memlog" as the node name instead of "sram," which was misleading.
- Link to v1: https://lore.kernel.org/r/20251117-mtd-memregion-v1-0-7b35611c79a6@bootlin.com

---
Gregory CLEMENT (3):
      of: reserved_mem: Support multiple 'reg' entries for memory-region
      dt-bindings: mtd: physmap: Allow using memory-region to access memory resources
      mtd: physmap: Add support for RAM reserved memory regions

 .../devicetree/bindings/mtd/mtd-physmap.yaml       |  59 ++++++---
 drivers/mtd/maps/physmap-core.c                    |  56 +++++++--
 drivers/of/of_reserved_mem.c                       | 139 +++++++++++++++++++--
 include/linux/of_reserved_mem.h                    |   4 +
 4 files changed, 218 insertions(+), 40 deletions(-)
---
base-commit: b55d426c390f2a4762b2a88b113cc44c37e08e46
change-id: 20251117-mtd-memregion-8830c1dd70ce

Best regards,
-- 
Grégory CLEMENT, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com