dt-bindings: hwmon: Add nuvoton,nct6775

These Super I/O chips have an i2c interface that some systems expose
to a BMC; the BMC's device tree can now describe that via this
binding.
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220428012707.24921-2-zev@bewilderbeest.netSigned-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/devicetree/bindings/hwmon/nuvoton,nct6775.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+
+$id: http://devicetree.org/schemas/hwmon/nuvoton,nct6775.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Nuvoton NCT6775 and compatible Super I/O chips
+
+maintainers:
+  - Zev Weiss <zev@bewilderbeest.net>
+
+properties:
+  compatible:
+    enum:
+      - nuvoton,nct6106
+      - nuvoton,nct6116
+      - nuvoton,nct6775
+      - nuvoton,nct6776
+      - nuvoton,nct6779
+      - nuvoton,nct6791
+      - nuvoton,nct6792
+      - nuvoton,nct6793
+      - nuvoton,nct6795
+      - nuvoton,nct6796
+      - nuvoton,nct6797
+      - nuvoton,nct6798
+
+  reg:
+    maxItems: 1
+
+  nuvoton,tsi-channel-mask:
+    description:
+      Bitmask indicating which TSI temperature sensor channels are
+      active.  LSB is TSI0, bit 1 is TSI1, etc.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 0xff
+    default: 0
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        superio@4d {
+            compatible = "nuvoton,nct6779";
+            reg = <0x4d>;
+            nuvoton,tsi-channel-mask = <0x03>;
+        };
+    };