dt-bindings: net: dsa: microchip: Add strap description to set SPI mode

At reset, KSZ8463 uses a strap-based configuration to set SPI as
interface bus. If the required pull-ups/pull-downs are missing (by
mistake or by design to save power) the pins may float and the
configuration can go wrong preventing any communication with the switch.

Add a 'reset' pinmux state
Add a KSZ8463 specific strap description that can be used by the driver
to drive the strap pins during reset. Two GPIOs are used. Users must
describe either both of them or none of them.

Signed-off-by: Bastien Curutchet (Schneider Electric) <bastien.curutchet@bootlin.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20250918-ksz-strap-pins-v3-2-16662e881728@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml b/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml
index db8175b4ced6d136ba97c371b68ba993637e444a..a8c8009414ae00b1a60aad715e15c23343e241ff 100644 (file)
--- a/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml
+++ b/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml
@@ -34,6 +34,13 @@ properties:
       - microchip,ksz8567
       - microchip,lan9646
 
+  pinctrl-names:
+    items:
+      - const: default
+      - const: reset
+        description:
+          Used during reset for strap configuration.
+
   reset-gpios:
     description:
       Should be a gpio specifier for a reset line.
@@ -139,6 +146,18 @@ allOf:
                     should be provided externally.
               dependencies:
                 microchip,rmii-clk-internal: [ethernet]
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: microchip,ksz8463
+    then:
+      properties:
+        straps-rxd-gpios:
+          description:
+            RXD0 and RXD1 pins, used to select SPI as bus interface.
+          minItems: 2
+          maxItems: 2
 
 unevaluatedProperties: false