[RFC PATCH 3/6] dt-bindings: xen: Add xen,dev-domid property description for xen-virtio layer

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>

Introduce Xen specific binding for the virtio-mmio device to be used
by Xen virtio support driver in a subsequent commit.

This binding specifies the ID of Xen domain where the corresponding
device (backend) resides. This is needed for the option to restrict
memory access using Xen grant mappings to work.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
---
 .../devicetree/bindings/virtio/xen,dev-domid.yaml  | 39 ++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/virtio/xen,dev-domid.yaml

diff --git a/Documentation/devicetree/bindings/virtio/xen,dev-domid.yaml 
b/Documentation/devicetree/bindings/virtio/xen,dev-domid.yaml
new file mode 100644
index 00000000..78be993
--- /dev/null
+++ b/Documentation/devicetree/bindings/virtio/xen,dev-domid.yaml
@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/virtio/xen,dev-domid.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Xen specific binding for the virtio device
+
+maintainers:
+  - Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
+
+select: true
+
+description:
+  This binding specifies the ID of Xen domain where the corresponding device
+  (backend) resides. This is needed for the option to restrict memory access
+  using Xen grant mappings to work.
+
+  Note that current and generic "iommus" bindings are mutually exclusive, since
+  the restricted memory access model on Xen behaves as a kind of software 
IOMMU.
+
+properties:
+  xen,dev-domid:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Should contain the ID of device's domain.
+
+additionalProperties: true
+
+examples:
+  - |
+    virtio_block@3000 {
+            compatible = "virtio,mmio";
+            reg = <0x3000 0x100>;
+            interrupts = <41>;
+
+            /* The device is located in Xen domain with ID 1 */
+            xen,dev-domid = <1>;
+    };
-- 
2.7.4