dt-bindings: virtio: Convert virtio,pci-iommu to DT schema

Convert the binding that describes the virtio-pci based IOMMU to DT
schema. Change the compatible string to "pci<vendor>,<device>", which is
defined by the PCI Bus Binding, but keep "virtio,pci-iommu" as an option
for backward compatibility.

Signed-off-by: Jean-Philippe Brucker <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Rob Herring <[e-mail]>

Documentation/devicetree/bindings/virtio/iommu.txt

···
-* virtio IOMMU PCI device
-
-When virtio-iommu uses the PCI transport, its programming interface is
-discovered dynamically by the PCI probing infrastructure. However the
-device tree statically describes the relation between IOMMU and DMA
-masters. Therefore, the PCI root complex that hosts the virtio-iommu
-contains a child node representing the IOMMU device explicitly.
-
-Required properties:
-
-- compatible:	Should be "virtio,pci-iommu"
-- reg:		PCI address of the IOMMU. As defined in the PCI Bus
-		Binding reference [1], the reg property is a five-cell
-		address encoded as (phys.hi phys.mid phys.lo size.hi
-		size.lo). phys.hi should contain the device's BDF as
-		0b00000000 bbbbbbbb dddddfff 00000000. The other cells
-		should be zero.
-- #iommu-cells:	Each platform DMA master managed by the IOMMU is assigned
-		an endpoint ID, described by the "iommus" property [2].
-		For virtio-iommu, #iommu-cells must be 1.
-
-Notes:
-
-- DMA from the IOMMU device isn't managed by another IOMMU. Therefore the
-  virtio-iommu node doesn't have an "iommus" property, and is omitted from
-  the iommu-map property of the root complex.
-
-Example:
-
-pcie@10000000 {
-	compatible = "pci-host-ecam-generic";
-	...
-
-	/* The IOMMU programming interface uses slot 00:01.0 */
-	iommu0: iommu@0008 {
-		compatible = "virtio,pci-iommu";
-		reg = <0x00000800 0 0 0 0>;
-		#iommu-cells = <1>;
-	};
-
-	/*
-	 * The IOMMU manages all functions in this PCI domain except
-	 * itself. Omit BDF 00:01.0.
-	 */
-	iommu-map = <0x0 &iommu0 0x0 0x8>
-		    <0x9 &iommu0 0x9 0xfff7>;
-};
-
-pcie@20000000 {
-	compatible = "pci-host-ecam-generic";
-	...
-	/*
-	 * The IOMMU also manages all functions from this domain,
-	 * with endpoint IDs 0x10000 - 0x1ffff
-	 */
-	iommu-map = <0x0 &iommu0 0x10000 0x10000>;
-};
-
-ethernet@fe001000 {
-	...
-	/* The IOMMU manages this platform device with endpoint ID 0x20000 */
-	iommus = <&iommu0 0x20000>;
-};
-
-[1] Documentation/devicetree/bindings/pci/pci.txt
-[2] Documentation/devicetree/bindings/iommu/iommu.txt

Documentation/devicetree/bindings/virtio/pci-iommu.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/virtio/pci-iommu.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: virtio-iommu device using the virtio-pci transport
+
+maintainers:
+  - Jean-Philippe Brucker <[e-mail]>
+
+description: |
+  When virtio-iommu uses the PCI transport, its programming interface is
+  discovered dynamically by the PCI probing infrastructure. However the
+  device tree statically describes the relation between IOMMU and DMA
+  masters. Therefore, the PCI root complex that hosts the virtio-iommu
+  contains a child node representing the IOMMU device explicitly.
+
+  DMA from the IOMMU device isn't managed by another IOMMU. Therefore the
+  virtio-iommu node doesn't have an "iommus" property, and is omitted from
+  the iommu-map property of the root complex.
+
+properties:
+  # If compatible is present, it should contain the vendor and device ID
+  # according to the PCI Bus Binding specification. Since PCI provides
+  # built-in identification methods, compatible is not actually required.
+  compatible:
+    oneOf:
+      - items:
+          - const: virtio,pci-iommu
+          - const: pci1af4,1057
+      - items:
+          - const: pci1af4,1057
+
+  reg:
+    description: |
+      PCI address of the IOMMU. As defined in the PCI Bus Binding
+      reference, the reg property is a five-cell address encoded as (phys.hi
+      phys.mid phys.lo size.hi size.lo). phys.hi should contain the device's
+      BDF as 0b00000000 bbbbbbbb dddddfff 00000000. The other cells should be
+      zero. See Documentation/devicetree/bindings/pci/pci.txt
+
+  '#iommu-cells':
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - '#iommu-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    bus {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        pcie@40000000 {
+            device_type = "pci";
+            #address-cells = <3>;
+            #size-cells = <2>;
+            reg = <0x0 0x40000000  0x0 0x1000000>;
+            ranges = <0x02000000 0x0 0x41000000  0x0 0x41000000  0x0 0x0f000000>;
+
+            /*
+             * The IOMMU manages all functions in this PCI domain except
+             * itself. Omit BDF 00:01.0.
+             */
+            iommu-map = <0x0 &iommu0 0x0 0x8
+                         0x9 &iommu0 0x9 0xfff7>;
+
+            /* The IOMMU programming interface uses slot 00:01.0 */
+            iommu0: iommu@1,0 {
+                compatible = "pci1af4,1057";
+                reg = <0x800 0 0 0 0>;
+                #iommu-cells = <1>;
+            };
+        };
+
+        pcie@50000000 {
+            device_type = "pci";
+            #address-cells = <3>;
+            #size-cells = <2>;
+            reg = <0x0 0x50000000  0x0 0x1000000>;
+            ranges = <0x02000000 0x0 0x51000000  0x0 0x51000000  0x0 0x0f000000>;
+
+            /*
+             * The IOMMU also manages all functions from this domain,
+             * with endpoint IDs 0x10000 - 0x1ffff
+             */
+            iommu-map = <0x0 &iommu0 0x10000 0x10000>;
+        };
+
+        ethernet {
+            /* The IOMMU manages this platform device with endpoint ID 0x20000 */
+            iommus = <&iommu0 0x20000>;
+        };
+    };
+
+...