dt-bindings: counter: microchip-tcb-capture counter

Describe the devicetree binding for the Microchip TCB module.
Each counter blocks exposes three independent counters.

However, when configured in quadrature decoder, both channel <0> and <1>
are required for speed/position and rotation capture (yet only the
position is captured).

Signed-off-by: Kamel Bouhara <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
Signed-off-by: Jonathan Cameron <[email protected]>

Documentation/devicetree/bindings/soc/microchip/atmel,at91rm9200-tcb.yaml

@@ -52,14 +52,20 @@ properties:
 
 patternProperties:
   "^timer@[0-2]$":
-    description: The timer block channels that are used as timers.
+    description: The timer block channels that are used as timers or counters.
     type: object
     properties:
       compatible:
-        const: atmel,tcb-timer
+        items:
+          - enum:
+              - atmel,tcb-timer
+              - microchip,tcb-capture
       reg:
         description:
-          List of channels to use for this particular timer.
+          List of channels to use for this particular timer. In Microchip TCB capture
+          mode channels are registered as a counter devices, for the qdec mode TCB0's
+          channel <0> and <1> are required.
+
         minItems: 1
         maxItems: 3
 
@@ -153,3 +159,23 @@ examples:
                         reg = <1>;
                 };
         };
+    /* TCB0 Capture with QDEC: */
+        timer@f800c000 {
+                compatible = "atmel,at91rm9200-tcb", "simple-mfd", "syscon";
+                #address-cells = <1>;
+                #size-cells = <0>;
+                reg = <0xfff7c000 0x100>;
+                interrupts = <18 4>;
+                clocks = <&tcb0_clk>, <&clk32k>;
+                clock-names = "t0_clk", "slow_clk";
+
+                timer@0 {
+                        compatible = "microchip,tcb-capture";
+                        reg = <0>, <1>;
+                };
+
+                timer@2 {
+                        compatible = "atmel,tcb-timer";
+                        reg = <2>;
+                };
+        };