[PATCH v10 1/3] dt-bindings: i2c: Add CP2112 HID USB to SMBus Bridge

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This is a USB HID device which includes an I2C controller and 8 GPIO pins.

The binding allows describing the chip's gpio and i2c controller in DT
using the subnodes named "gpio" and "i2c", respectively. This is
intended to be used in configurations where the CP2112 is permanently
connected in hardware.

Signed-off-by: Danny Kaehn <danny.kaehn@xxxxxxxxxx>
---

Note -- Reviewed-By tags have been removed as suggested by Benjamin, since
1. It has been 6+ months since this binding was reviewed, and a lot can
change upstream in that time
2. There has been some contention between using named child nodes to
identify i2c and gpio nodes, and also making the driver implementing this
binding compatible with ACPI, since names aren't significant for ACPI
nodes, and ACPI names are always automatically uppercased. It has been
suggested that perhaps the DT binding should use child nodes with
addressable `reg` properties to identify the child nodes, instead of by
name [1].

Of course, I acknowledge that other firmware languages and kernel details
shouldn't impact DT bindings, but it also seems that there should
be some consistent way to specify sub-functions like this accross DT
and ACPI. Some additional commentary / requests for comment about the
seemingly missing glue here can be found in [2].

Any comments from Rob/Krzysztof/other DT folks would be greatly appreciated

[1] https://lore.kernel.org/all/ZBhoHzTr5l38u%2FkX@xxxxxxxxxxxxxxxxxx/
[2] https://lore.kernel.org/all/CAP+ZCCd0cD+q7=ngyEzScAte2VT9R00mqCQxB3K2TMbeg8UAfA@xxxxxxxxxxxxxx/

 .../bindings/i2c/silabs,cp2112.yaml           | 113 ++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/silabs,cp2112.yaml

diff --git a/Documentation/devicetree/bindings/i2c/silabs,cp2112.yaml b/Documentation/devicetree/bindings/i2c/silabs,cp2112.yaml
new file mode 100644
index 000000000000..a27509627804
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/silabs,cp2112.yaml
@@ -0,0 +1,113 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/i2c/silabs,cp2112.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: CP2112 HID USB to SMBus/I2C Bridge
+
+maintainers:
+  - Danny Kaehn <kaehndan@xxxxxxxxx>
+
+description:
+  The CP2112 is a USB HID device which includes an integrated I2C controller
+  and 8 GPIO pins. Its GPIO pins can each be configured as inputs, open-drain
+  outputs, or push-pull outputs.
+
+properties:
+  compatible:
+    const: usb10c4,ea90
+
+  reg:
+    maxItems: 1
+    description: The USB port number on the host controller
+
+  i2c:
+    description: The SMBus/I2C controller node for the CP2112
+    $ref: /schemas/i2c/i2c-controller.yaml#
+    unevaluatedProperties: false
+
+    properties:
+      sda-gpios:
+        maxItems: 1
+
+      scl-gpios:
+        maxItems: 1
+
+      clock-frequency:
+        minimum: 10000
+        default: 100000
+        maximum: 400000
+
+  gpio:
+    description: The GPIO controller node for the CP2112
+    type: object
+    unevaluatedProperties: false
+
+    properties:
+      interrupt-controller: true
+      "#interrupt-cells":
+        const: 2
+
+      gpio-controller: true
+      "#gpio-cells":
+        const: 2
+
+      gpio-line-names:
+        minItems: 1
+        maxItems: 8
+
+    patternProperties:
+      "-hog(-[0-9]+)?$":
+        type: object
+
+        required:
+          - gpio-hog
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/gpio/gpio.h>
+
+    usb {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      device@1 {
+        compatible = "usb10c4,ea90";
+        reg = <1>;
+
+        i2c {
+          #address-cells = <1>;
+          #size-cells = <0>;
+          sda-gpios = <&cp2112_gpio 0 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
+          scl-gpios = <&cp2112_gpio 1 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
+
+          temp@48 {
+            compatible = "national,lm75";
+            reg = <0x48>;
+          };
+        };
+
+        cp2112_gpio: gpio {
+          gpio-controller;
+          interrupt-controller;
+          #gpio-cells = <2>;
+          gpio-line-names = "CP2112_SDA", "CP2112_SCL", "TEST2",
+            "TEST3","TEST4", "TEST5", "TEST6";
+
+          fan-rst-hog {
+              gpio-hog;
+              gpios = <7 GPIO_ACTIVE_HIGH>;
+              output-high;
+              line-name = "FAN_RST";
+          };
+        };
+      };
+    };
-- 
2.25.1





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