dt-bindings: iio: adc: adi,ad7606: add conditions

Since the driver supports several parts that present differences in
their layout and behaviour, it is necessary to describe the differences
from one chip to another.
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Guillaume Stols <gstols@baylibre.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/adi,ad7606.yaml

@@ -52,10 +52,11 @@ properties:
 
   adi,conversion-start-gpios:
     description:
-      Must be the device tree identifier of the CONVST pin. This logic input is
-      used to initiate conversions on the analog input channels. As the line is
-      active high, it should be marked GPIO_ACTIVE_HIGH.
-    maxItems: 1
+      Must be the device tree identifier of the CONVST pin(s). This logic input
+      is used to initiate conversions on the analog input channels. As the line
+      is active high, it should be marked GPIO_ACTIVE_HIGH.
+    minItems: 1
+    maxItems: 2
 
   reset-gpios:
     description:
@@ -88,8 +89,11 @@ properties:
       is tied to a logic high, the analog input range is ±10V for all channels.
       On the AD760X, if this pin is tied to a logic low, the analog input range
       is ±5V for all channels. As the line is active high, it should be marked
-      GPIO_ACTIVE_HIGH.
-    maxItems: 1
+      GPIO_ACTIVE_HIGH. On the AD7616, there are 2 pins, and if the 2 pins are
+      tied to a logic high, software mode is enabled, otherwise one of the 3
+      possible range values is selected.
+    minItems: 1
+    maxItems: 2
 
   adi,oversampling-ratio-gpios:
     description:
@@ -122,6 +126,50 @@ required:
 allOf:
   - $ref: /schemas/spi/spi-peripheral-props.yaml#
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: adi,ad7616
+    then:
+      properties:
+        adi,first-data-gpios: false
+        standby-gpios: false
+        adi,range-gpios:
+          maxItems: 2
+    else:
+      properties:
+        adi,range-gpios:
+          maxItems: 1
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - adi,ad7605-4
+              - adi,ad7616
+    then:
+      properties:
+        adi,oversampling-ratio-gpios: false
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - adi,ad7605-4
+              - adi,ad7606-4
+              - adi,ad7606-6
+              - adi,ad7606-8
+    then:
+      properties:
+        adi,sw-mode: false
+    else:
+      properties:
+        adi,conversion-start-gpios:
+          maxItems: 1
+
 unevaluatedProperties: false
 
 examples: