dt-bindings:iio:temperature:maxim_thermocouple.txt to maxim,max31855k.yaml

Given we already have another maxim thermocouple driver that isn't
covered by this binding it seems a better idea to chose to name it
after a specific part.

I added an additional example for the maxim,max6755 to illustrate
the need for spi-cpha for that part.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Matt Ranostay <matt.ranostay@konsulko.com>
Link: https://lore.kernel.org/r/20201031134110.724233-29-jic23@kernel.org

Documentation/devicetree/bindings/iio/temperature/maxim,max31855k.yaml

@@ -0,0 +1,76 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/temperature/maxim,max31855k.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim MAX31855 and similar thermocouples
+
+maintainers:
+  - Matt Ranostay <matt.ranostay@konsulko.com>
+
+description: |
+  https://datasheets.maximintegrated.com/en/ds/MAX6675.pdf
+  https://datasheets.maximintegrated.com/en/ds/MAX31855.pdf
+
+properties:
+  compatible:
+    description:
+      The generic maxim,max31855 compatible is deprecated in favour of
+      the thermocouple type specific variants.
+    enum:
+      - maxim,max6675
+      - maxim,max31855
+      - maxim,max31855k
+      - maxim,max31855j
+      - maxim,max31855n
+      - maxim,max31855s
+      - maxim,max31855t
+      - maxim,max31855e
+      - maxim,max31855r
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency: true
+  spi-cpha: true
+
+required:
+  - compatible
+  - reg
+
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - maxim,max6675
+    then:
+      required:
+        - spi-cpha
+    else:
+      properties:
+        spi-cpha: false
+
+additionalProperties: false
+
+examples:
+  - |
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        temp-sensor@0 {
+            compatible = "maxim,max31855k";
+            reg = <0>;
+            spi-max-frequency = <4300000>;
+        };
+        temp-sensor@1 {
+            compatible = "maxim,max6675";
+            reg = <1>;
+            spi-max-frequency = <4300000>;
+            spi-cpha;
+        };
+    };
+...