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Date:   Wed, 14 Jul 2021 17:10:08 +0530
From:   Viresh Kumar <viresh.kumar@linaro.org>
To:     Arnd Bergmann <arnd@kernel.org>
Cc:     Rob Herring <robh+dt@kernel.org>, Jason Wang <jasowang@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Bill Mills <bill.mills@linaro.org>,
        Alex =?utf-8?Q?Benn=C3=A9e?= <alex.bennee@linaro.org>,
        "Enrico Weigelt, metux IT consult" <info@metux.net>,
        Jie Deng <jie.deng@intel.com>,
        DTML <devicetree@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "open list:DRM DRIVER FOR QEMU'S CIRRUS DEVICE" 
        <virtualization@lists.linux-foundation.org>
Subject: Re: [PATCH 1/5] dt-bindings: virtio: mmio: Add support for device
 subnode
Message-ID: <20210714114008.kohvyz57fvrd7syu@vireshk-i7>
References: <cover.1626173013.git.viresh.kumar@linaro.org>
 <aa4bf68fdd13b885a6dc1b98f88834916d51d97d.1626173013.git.viresh.kumar@linaro.org>
 <CAL_Jsq+SiE+ciZfASHKUfLU1YMPfB43YmSciT_+gQHvL99_wUA@mail.gmail.com>
 <20210713151917.zouwfckidnjxvohn@vireshk-i7>
 <CAL_JsqL9255n5RT=Gq_uru7rEP0bSVcyfXEPRY4F0M4S2HPvTA@mail.gmail.com>
 <CAK8P3a3Gve=M9GF-E+2OJED1Hd1qngxOkVSO15wB0jVWK8D0_Q@mail.gmail.com>
 <20210714022630.d7vrazygmbooflcf@vireshk-i7>
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On 14-07-21, 07:56, Viresh Kumar wrote:
> I agree that even if the device is discoverable at runtime, we should
> still have some sort of stuff in DT to distinguish the devices, and
> "virtio,deviceDID" sounds good enough for that, considering that we
> already do it for USB, etc.
> 
> And I am fine with both the ways, a new node or just using the parent
> node. So whatever you guys decide is fine.

I tried to write and see what it would look like after using the
existing nodes for mmio/pci and here is what I got.  (I couldn't find
any virtio-pci bindings and so stayed away from adding any reference
to it here).

Does that look better ?

-- 
viresh

-------------------------8<-------------------------
diff --git a/Documentation/devicetree/bindings/virtio/mmio.yaml b/Documentation/devicetree/bindings/virtio/mmio.yaml
index d46597028cf1..324b810e51a5 100644
--- a/Documentation/devicetree/bindings/virtio/mmio.yaml
+++ b/Documentation/devicetree/bindings/virtio/mmio.yaml
@@ -15,7 +15,8 @@ title: virtio memory mapped devices
 
 properties:
   compatible:
-    const: virtio,mmio
+    contains:
+      const: virtio,mmio
 
   reg:
     maxItems: 1
@@ -36,7 +37,7 @@ title: virtio memory mapped devices
   - reg
   - interrupts
 
-additionalProperties: false
+additionalProperties: true
 
 examples:
   - |
diff --git a/Documentation/devicetree/bindings/virtio/virtio-device.yaml b/Documentation/devicetree/bindings/virtio/virtio-device.yaml
new file mode 100644
index 000000000000..9cfe090ea65f
--- /dev/null
+++ b/Documentation/devicetree/bindings/virtio/virtio-device.yaml
@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/virtio/virtio-device.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Virtio device bindings
+
+maintainers:
+  - Viresh Kumar <viresh.kumar@linaro.org>
+
+description:
+  These bindings are applicable to virtio devices irrespective of the bus they
+  are bound to, like mmio or pci.
+
+allOf:
+  - $ref: /schemas/virtio/mmio.yaml#
+
+# We need a select here so we don't match all nodes with 'virtio,mmio'
+select:
+  properties:
+    compatible:
+      contains:
+        pattern: '^virtio,[0-9]+$'
+  required:
+    - compatible
+
+properties:
+  compatible:
+    contains:
+      oneOf:
+        - items:
+          - const: virtio,mmio
+          - pattern: '^virtio,[0-9]+$'
+
+required:
+  - compatible
+
+additionalProperties: true
+
+examples:
+  - |
+    i2c: i2c-virtio@3000 {
+        compatible = "virtio,mmio", "virtio,34";
+        reg = <0x3000 0x100>;
+        interrupts = <41>;
+    };
+
+...
diff --git a/Documentation/devicetree/bindings/gpio/gpio-virtio.yaml b/Documentation/devicetree/bindings/gpio/gpio-virtio.yaml
new file mode 100644
index 000000000000..8115ba794557
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-virtio.yaml
@@ -0,0 +1,63 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/gpio-virtio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Virtio GPIO controller
+
+maintainers:
+  - Viresh Kumar <viresh.kumar@linaro.org>
+
+allOf:
+  - $ref: /schemas/gpio/gpio.yaml#
+  - $ref: /schemas/virtio/virtio-device.yaml#
+
+# We need a select here so we don't match all nodes with 'virtio,mmio'
+select:
+  properties:
+    compatible:
+      contains:
+        enum:
+          - virtio,41
+  required:
+    - compatible
+
+properties:
+  compatible:
+    oneOf:
+      - items:
+        - const: virtio,mmio
+        - const: virtio,41
+
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 2
+
+  interrupt-controller: true
+
+  "#interrupt-cells":
+    const: 2
+
+required:
+  - compatible
+  - gpio-controller
+  - "#gpio-cells"
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    gpio: gpio-virtio@3000 {
+        compatible = "virtio,mmio", "virtio,41";
+        reg = <0x3000 0x100>;
+        interrupts = <41>;
+
+        gpio-controller;
+        #gpio-cells = <2>;
+        interrupt-controller;
+        #interrupt-cells = <2>;
+    };
+
+...
diff --git a/Documentation/devicetree/bindings/i2c/i2c-virtio.yaml b/Documentation/devicetree/bindings/i2c/i2c-virtio.yaml
new file mode 100644
index 000000000000..43e9910920d6
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-virtio.yaml
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/i2c/i2c-virtio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Virtio I2C Adapter
+
+maintainers:
+  - Viresh Kumar <viresh.kumar@linaro.org>
+
+allOf:
+  - $ref: /schemas/i2c/i2c-controller.yaml#
+  - $ref: /schemas/virtio/virtio-device.yaml#
+
+# We need a select here so we don't match all nodes with 'virtio,mmio'
+select:
+  properties:
+    compatible:
+      contains:
+        enum:
+          - virtio,34
+  required:
+    - compatible
+
+properties:
+  compatible:
+    oneOf:
+      - items:
+        - const: virtio,mmio
+        - const: virtio,34
+
+required:
+  - compatible
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    i2c: i2c-virtio@3000 {
+        compatible = "virtio,mmio", "virtio,34";
+        reg = <0x3000 0x100>;
+        interrupts = <41>;
+
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        light-sensor@1c {
+            compatible = "dynaimage,al3320a";
+            reg = <0x20>;
+        };
+    };
+
+...