netdev - [PATCH net-next v2 2/3] dt-bindings: net: dsa: microchip: Add strap description to set SPI mode

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Message-Id: <20250912-ksz-strap-pins-v2-2-6d97270c6926@bootlin.com>
Date: Fri, 12 Sep 2025 11:09:13 +0200
From: "Bastien Curutchet (Schneider Electric)" <bastien.curutchet@...tlin.com>
To: Woojung Huh <woojung.huh@...rochip.com>, UNGLinuxDriver@...rochip.com, 
 Andrew Lunn <andrew@...n.ch>, Vladimir Oltean <olteanv@...il.com>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Marek Vasut <marex@...x.de>
Cc: Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 Miquèl Raynal <miquel.raynal@...tlin.com>, 
 Pascal Eberhard <pascal.eberhard@...com>, 
 Woojung Huh <Woojung.Huh@...rochip.com>, netdev@...r.kernel.org, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 "Bastien Curutchet (Schneider Electric)" <bastien.curutchet@...tlin.com>
Subject: [PATCH net-next v2 2/3] 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@...tlin.com>
---
 .../devicetree/bindings/net/dsa/microchip,ksz.yaml | 24 ++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml b/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml
index db8175b4ced6d136ba97c371b68ba993637e444a..099c6b373704427755c3d8cad4b1cd930219f2f2 100644
--- 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 +146,23 @@ allOf:
                     should be provided externally.
               dependencies:
                 microchip,rmii-clk-internal: [ethernet]
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: microchip,ksz8463
+    then:
+      properties:
+        strap-rxd0-gpios:
+          description:
+            RXD0 pin, used to select SPI as bus interface.
+        strap-rxd1-gpios:
+          description:
+            RXD1 pin, used to select SPI as bus interface.
+
+dependencies:
+  strap-rxd0-gpios: [ strap-rxd1-gpios ]
+  strap-rxd1-gpios: [ strap-rxd0-gpios ]

 unevaluatedProperties: false

-- 
2.51.0