[v4,1/4] Add reserved-memory

diff --git a/dtschema/schemas/reserved-memory/reserved-memory.yaml b/dtschema/schemas/reserved-memory/reserved-memory.yaml
new file mode 100644
index 0000000..c680e39
--- /dev/null
+++ b/dtschema/schemas/reserved-memory/reserved-memory.yaml
@@ -0,0 +1,181 @@ 
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/reserved-memory/reserved-memory.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: /reserved-memory Child Node Common
+
+maintainers:
+  - devicetree-spec@vger.kernel.org
+
+description: >
+  Reserved memory is specified as a node under the /reserved-memory node. The
+  operating system shall exclude reserved memory from normal usage one can
+  create child nodes describing particular reserved (excluded from normal use)
+  memory regions. Such memory regions are usually designed for the special
+  usage by various device drivers.
+
+  Each child of the reserved-memory node specifies one or more regions
+  of reserved memory. Each child node may either use a 'reg' property to
+  specify a specific range of reserved memory, or a 'size' property with
+  optional constraints to request a dynamically allocated block of
+  memory.
+
+  Following the generic-names recommended practice, node names should
+  reflect the purpose of the node (ie. "framebuffer" or "dma-pool").
+  Unit address (@<address>) should be appended to the name if the node
+  is a static allocation.
+
+properties:
+  reg: true
+
+  size:
+    oneOf:
+      - $ref: /schemas/types.yaml#/definitions/uint32
+      - $ref: /schemas/types.yaml#/definitions/uint64
+    description: >
+      Length based on parent's \#size-cells. Size in bytes of memory to
+      reserve.
+
+  alignment:
+    oneOf:
+      - $ref: /schemas/types.yaml#/definitions/uint32
+      - $ref: /schemas/types.yaml#/definitions/uint64
+    description: >
+      Length based on parent's \#size-cells. Address boundary for
+      alignment of allocation.
+
+  alloc-ranges:
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    description: >
+      Address and Length pairs. Specifies regions of memory that are
+      acceptable to allocate from.
+
+  iommu-addresses:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    description: >
+      A list of phandle and specifier pairs that describe static IO virtual
+      address space mappings and carveouts associated with a given reserved
+      memory region. The phandle in the first cell refers to the device for
+      which the mapping or carveout is to be created.
+
+      The specifier consists of an address/size pair and denotes the IO
+      virtual address range of the region for the given device. The exact
+      format depends on the values of the "#address-cells" and "#size-cells"
+      properties of the device referenced via the phandle.
+
+      When used in combination with a "reg" property, an IOVA mapping is to
+      be established for this memory region. One example where this can be
+      useful is to create an identity mapping for physical memory that the
+      firmware has configured some hardware to access (such as a bootsplash
+      framebuffer).
+
+      If no "reg" property is specified, the "iommu-addresses" property
+      defines carveout regions in the IOVA space for the given device. This
+      can be useful if a certain memory region should not be mapped through
+      the IOMMU.
+
+  no-map:
+    type: boolean
+    description: >
+      Indicates the operating system must not create a virtual mapping
+      of the region as part of its standard mapping of system memory,
+      nor permit speculative access to it under any circumstances other
+      than under the control of the device driver using the region.
+
+  reusable:
+    type: boolean
+    description: >
+      The operating system can use the memory in this region with the
+      limitation that the device driver(s) owning the region need to be
+      able to reclaim it back. Typically that means that the operating
+      system can use that region to store volatile or cached data that
+      can be otherwise regenerated or migrated elsewhere.
+
+allOf:
+  - if:
+      required:
+        - no-map
+
+    then:
+      not:
+        required:
+          - reusable
+
+  - if:
+      required:
+        - reusable
+
+    then:
+      not:
+        required:
+          - no-map
+
+oneOf:
+  - oneOf:
+      - required:
+          - reg
+
+      - required:
+          - size
+
+  - oneOf:
+      # IOMMU reservations
+      - required:
+          - iommu-addresses
+
+      # IOMMU mappings
+      - required:
+          - reg
+          - iommu-addresses
+
+additionalProperties: true
+
+examples:
+  - |
+    / {
+      compatible = "foo";
+      model = "foo";
+
+      #address-cells = <2>;
+      #size-cells = <2>;
+
+      reserved-memory {
+        #address-cells = <2>;
+        #size-cells = <2>;
+        ranges;
+
+        adsp_resv: reservation-adsp {
+          /*
+           * Restrict IOVA mappings for ADSP buffers to the 512 MiB region
+           * from 0x40000000 - 0x5fffffff. Anything outside is reserved by
+           * the ADSP for I/O memory and private memory allocations.
+           */
+          iommu-addresses = <&adsp 0x0 0x00000000 0x00 0x40000000>,
+                            <&adsp 0x0 0x60000000 0xff 0xa0000000>;
+        };
+
+        fb: framebuffer@90000000 {
+          reg = <0x0 0x90000000 0x0 0x00800000>;
+          iommu-addresses = <&dc0 0x0 0x90000000 0x0 0x00800000>;
+        };
+      };
+
+      bus@0 {
+        #address-cells = <1>;
+        #size-cells = <1>;
+        ranges = <0x0 0x0 0x0 0x40000000>;
+
+        adsp: adsp@2990000 {
+          reg = <0x2990000 0x2000>;
+          memory-region = <&adsp_resv>;
+        };
+
+        dc0: display@15200000 {
+          reg = <0x15200000 0x10000>;
+          memory-region = <&fb>;
+        };
+      };
+    };
+...