Add a compatible for the ST ST21NFCD NFC controller. Document optional
SYS_CLK (clocks) and VPS_IO (vdd-io-supply).

ST21NFCD is not I2C-only; the ST data brief lists I2C and SPI.
Split the spi-max-frequency if/else: forbid it for
st,st21nfcb-i2c and st,st21nfcc-i2c, require it for st,st21nfcb-spi,
and leave it optional for st,st21nfcd. Add clocks and vdd-io-supply to
the existing st,st21nfcb-i2c example instead of a second I2C example.

Signed-off-by: Kristian Brox <isyourbrainfoss@proton.me>
---
 .../devicetree/bindings/net/nfc/st,st-nci.yaml     | 49 +++++++++++++++-------
 1 file changed, 35 insertions(+), 14 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/nfc/st,st-nci.yaml b/Documentation/devicetree/bindings/net/nfc/st,st-nci.yaml
index 1dcbddbc5a74..8abafb3d8994 100644
--- a/Documentation/devicetree/bindings/net/nfc/st,st-nci.yaml
+++ b/Documentation/devicetree/bindings/net/nfc/st,st-nci.yaml
@@ -15,6 +15,7 @@ properties:
       - st,st21nfcb-i2c
       - st,st21nfcb-spi
       - st,st21nfcc-i2c
+      - st,st21nfcd
 
   reset-gpios:
     description: Output GPIO pin used for resetting the controller
@@ -36,26 +37,43 @@ properties:
       Specifies that the uicc swp signal can be physically connected to the
       controller
 
+  clocks:
+    maxItems: 1
+    description:
+      External reference clock connected to SYS_CLK.
+
+  vdd-io-supply:
+    description:
+      Digital I/O supply (VPS_IO).
+
 required:
   - compatible
   - interrupts
   - reg
   - reset-gpios
 
-if:
-  properties:
-    compatible:
-      contains:
-        enum:
-          - st,st21nfcb-i2c
-          - st,st21nfcc-i2c
-then:
-  properties:
-    spi-max-frequency: false
-else:
-  $ref: /schemas/spi/spi-peripheral-props.yaml#
-  required:
-    - spi-max-frequency
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - st,st21nfcb-i2c
+              - st,st21nfcc-i2c
+    then:
+      properties:
+        spi-max-frequency: false
+    else:
+      $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: st,st21nfcb-spi
+    then:
+      required:
+        - spi-max-frequency
 
 unevaluatedProperties: false
 
@@ -76,6 +94,9 @@ examples:
             interrupts = <2 IRQ_TYPE_LEVEL_HIGH>;
             reset-gpios = <&gpio5 29 GPIO_ACTIVE_HIGH>;
 
+            clocks = <&clk>;
+            vdd-io-supply = <&vdd_io>;
+
             ese-present;
             uicc-present;
         };

-- 
2.55.0