[PATCH v3 1/2] dt-bindings: spi: add spi-virtio

[Francesco Valla <francesco@valla.it>]

Add bindings for spi-virtio based on virtio-device, allowing proper
validation of SPI controller nodes declared as children of virtio
transports (e.g.: virtio-mmio). Such nodes are not used to instantiate
devices, which are registered by the virtio transport, but to define
their properties and establish dependencies with other nodes.

The compatible follows what the virtio framework already searches for,
"2d" being the hexadecimal representation of the SPI controller device
ID defined by the virtio specification [1].

[1] https://docs.oasis-open.org/virtio/virtio/v1.4/virtio-v1.4.html

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Francesco Valla <francesco@valla.it>
---
 .../devicetree/bindings/spi/spi-virtio.yaml        | 46 ++++++++++++++++++++++
 MAINTAINERS                                        |  1 +
 2 files changed, 47 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/spi-virtio.yaml b/Documentation/devicetree/bindings/spi/spi-virtio.yaml
new file mode 100644
index 000000000000..5fc04a9c62cc
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/spi-virtio.yaml
@@ -0,0 +1,46 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/spi/spi-virtio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Virtio SPI controller device
+
+maintainers:
+  - Francesco Valla <francesco@valla.it>
+
+allOf:
+  - $ref: /schemas/spi/spi-controller.yaml#
+  - $ref: /schemas/virtio/virtio-device.yaml#
+
+properties:
+  compatible:
+    const: virtio,device2d
+
+required:
+  - compatible
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    virtio@3000 {
+        compatible = "virtio,mmio";
+        reg = <0x3000 0x100>;
+        interrupts = <41>;
+
+        spi {
+            compatible = "virtio,device2d";
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            sram@0 {
+                compatible = "microchip,mchp23k256";
+                reg = <0>;
+                spi-max-frequency = <20000000>;
+            };
+        };
+    };
+
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 03649f08c7c7..5724645bf703 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -29675,6 +29675,7 @@ VIRTIO SPI DRIVER
 M:	Haixu Cui <quic_haixcui@quicinc.com>
 L:	virtualization@lists.linux.dev
 S:	Maintained
+F:	Documentation/devicetree/bindings/spi/spi-virtio.yaml
 F:	drivers/spi/spi-virtio.c
 F:	include/uapi/linux/virtio_spi.h
 

-- 
2.56.0