dt-bindings: pmem: Convert binding to YAML

Convert the PMEM device tree binding from text to YAML. This will allow
device trees with pmem-region nodes to pass dtbs_check.

[iweiny: fix ups from Rob/Drew]

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Drew Fustini <drew@pdp7.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/20250606184405.359812-4-drew@pdp7.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

Author: pdp7

Documentation/devicetree/bindings/pmem/pmem-region.txt

@@ -0,0 +1,48 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pmem-region.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+maintainers:
+  - Oliver O'Halloran <oohall@gmail.com>
+
+title: Persistent Memory Regions
+
+description: |
+  Persistent memory refers to a class of memory devices that are:
+
+    a) Usable as main system memory (i.e. cacheable), and
+    b) Retain their contents across power failure.
+
+  Given b) it is best to think of persistent memory as a kind of memory mapped
+  storage device. To ensure data integrity the operating system needs to manage
+  persistent regions separately to the normal memory pool. To aid with that this
+  binding provides a standardised interface for discovering where persistent
+  memory regions exist inside the physical address space.
+
+properties:
+  compatible:
+    const: pmem-region
+
+  reg:
+    maxItems: 1
+
+  volatile:
+    description:
+      Indicates the region is volatile (non-persistent) and the OS can skip
+      cache flushes for writes
+    type: boolean
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    pmem@5000 {
+        compatible = "pmem-region";
+        reg = <0x00005000 0x00001000>;
+    };

Documentation/devicetree/bindings/pmem/pmem-region.yaml

@@ -13798,7 +13798,7 @@ M:	Oliver O'Halloran <oohall@gmail.com>
 L:	nvdimm@lists.linux.dev
 S:	Supported
 Q:	https://patchwork.kernel.org/project/linux-nvdimm/list/
-F:	Documentation/devicetree/bindings/pmem/pmem-region.txt
+F:	Documentation/devicetree/bindings/pmem/pmem-region.yaml
 F:	drivers/nvdimm/of_pmem.c
 
 LIBNVDIMM: NON-VOLATILE MEMORY DEVICE SUBSYSTEM