[PATCH 4/6] dt-bindings: pinctrl: rt2880: add proper function muxing binding

["Arınç ÜNAL" <arinc.unal@arinc9.com>]

Not every function can be muxed to a group. Add proper binding which
documents which function can be muxed to a group or set of groups.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
---
 .../pinctrl/ralink,rt2880-pinctrl.yaml        | 85 +++++++++++++++++--
 1 file changed, 79 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/pinctrl/ralink,rt2880-pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/ralink,rt2880-pinctrl.yaml
index 56e5becabcfd..f59ddd5e6c2b 100644
--- a/Documentation/devicetree/bindings/pinctrl/ralink,rt2880-pinctrl.yaml
+++ b/Documentation/devicetree/bindings/pinctrl/ralink,rt2880-pinctrl.yaml
@@ -29,18 +29,92 @@ patternProperties:
         $ref: pinmux-node.yaml#
 
         properties:
-          groups:
-            description: The pin group to select.
-            enum: [i2c, spi, uartlite, jtag, mdio, sdram, pci]
-
           function:
-            description: The mux function to select.
+            description:
+              A string containing the name of the function to mux to the group.
             enum: [gpio, i2c, spi, uartlite, jtag, mdio, sdram, pci]
 
+          groups:
+            description:
+              An array of strings. Each string contains the name of a group.
+
         required:
           - groups
           - function
 
+        allOf:
+          - if:
+              properties:
+                function:
+                  const: gpio
+            then:
+              properties:
+                groups:
+                  enum: [i2c, spi, uartlite, jtag, mdio, sdram, pci]
+
+          - if:
+              properties:
+                function:
+                  const: i2c
+            then:
+              properties:
+                groups:
+                  enum: [i2c]
+
+          - if:
+              properties:
+                function:
+                  const: spi
+            then:
+              properties:
+                groups:
+                  enum: [spi]
+
+          - if:
+              properties:
+                function:
+                  const: uartlite
+            then:
+              properties:
+                groups:
+                  enum: [uartlite]
+
+          - if:
+              properties:
+                function:
+                  const: jtag
+            then:
+              properties:
+                groups:
+                  enum: [jtag]
+
+          - if:
+              properties:
+                function:
+                  const: mdio
+            then:
+              properties:
+                groups:
+                  enum: [mdio]
+
+          - if:
+              properties:
+                function:
+                  const: sdram
+            then:
+              properties:
+                groups:
+                  enum: [sdram]
+
+          - if:
+              properties:
+                function:
+                  const: pci
+            then:
+              properties:
+                groups:
+                  enum: [pci]
+
         additionalProperties: false
 
     additionalProperties: false
@@ -54,7 +128,6 @@ required:
 additionalProperties: false
 
 examples:
-  # Pinmux controller node
   - |
     pinctrl {
       compatible = "ralink,rt2880-pinctrl";
-- 
2.37.2