[PATCH net-next v2 0/3] net: dsa: microchip: Add strap description to set SPI as interface bus

[PATCH net-next v2 0/3] net: dsa: microchip: Add strap description to set SPI as interface bus

[Bastien Curutchet (Schneider Electric)]

Hi all,

At reset, the 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.

This small series aims to allow to configure the KSZ8463 switch at
reset when the hardware straps are missing.

PATCH 0 and 1 add new properties to the bindings that describes the GPIOs
to be set during reset in order to configure the switch properly.

PATCH 2 implements the use of these properties in the driver.

Signed-off-by: Bastien Curutchet (Schneider Electric) <bastien.curutchet@bootlin.com>
---
Changes in v2:
- Make the changes specific to the KSZ8463 both in the bindings and in
  the driver.
- Link to v1: https://lore.kernel.org/r/20250910-ksz-strap-pins-v1-0-6308bb2e139e@bootlin.com

---
Bastien Curutchet (1):
      net: dsa: microchip: Set SPI as bus interface during reset for KSZ8463

Bastien Curutchet (Schneider Electric) (2):
      dt-bindings: net: dsa: microchip: Group if clause under allOf tag
      dt-bindings: net: dsa: microchip: Add strap description to set SPI mode

 .../devicetree/bindings/net/dsa/microchip,ksz.yaml | 92 ++++++++++++++--------
 drivers/net/dsa/microchip/ksz_common.c             | 45 +++++++++++
 2 files changed, 103 insertions(+), 34 deletions(-)
---
base-commit: d0b93fbf220b2e7be093ac336eba3433cf3cd6f0
change-id: 20250904-ksz-strap-pins-2d1305441325

Best regards,
-- 
Bastien Curutchet (Schneider Electric) <bastien.curutchet@bootlin.com>

[PATCH net-next v2 1/3] dt-bindings: net: dsa: microchip: Group if clause under allOf tag

[Bastien Curutchet (Schneider Electric)]

Upcoming patch adds a new if/then clause. It requires to be grouped with
the already existing if/then clause under an 'allOf:' tag.

Move the if/then clause under the already existing 'allOf:' tag to
prepare next patch.

Signed-off-by: Bastien Curutchet (Schneider Electric) <bastien.curutchet@bootlin.com>
---
 .../devicetree/bindings/net/dsa/microchip,ksz.yaml | 68 +++++++++++-----------
 1 file changed, 34 insertions(+), 34 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml b/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml
index eb4607460db7f32a4dffd416e44b61c2674f731e..db8175b4ced6d136ba97c371b68ba993637e444a 100644
--- a/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml
+++ b/Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml
@@ -10,9 +10,6 @@ maintainers:
   - Marek Vasut <marex@denx.de>
   - Woojung Huh <Woojung.Huh@microchip.com>
 
-allOf:
-  - $ref: /schemas/spi/spi-peripheral-props.yaml#
-
 properties:
   # See Documentation/devicetree/bindings/net/dsa/dsa.yaml for a list of additional
   # required and optional properties.
@@ -107,38 +104,41 @@ required:
   - compatible
   - reg
 
-if:
-  not:
-    properties:
-      compatible:
-        enum:
-          - microchip,ksz8863
-          - microchip,ksz8873
-then:
-  $ref: dsa.yaml#/$defs/ethernet-ports
-else:
-  patternProperties:
-    "^(ethernet-)?ports$":
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+  - if:
+      not:
+        properties:
+          compatible:
+            enum:
+              - microchip,ksz8863
+              - microchip,ksz8873
+    then:
+      $ref: dsa.yaml#/$defs/ethernet-ports
+    else:
       patternProperties:
-        "^(ethernet-)?port@[0-2]$":
-          $ref: dsa-port.yaml#
-          unevaluatedProperties: false
-          properties:
-            microchip,rmii-clk-internal:
-              $ref: /schemas/types.yaml#/definitions/flag
-              description:
-                When ksz88x3 is acting as clock provier (via REFCLKO) it
-                can select between internal and external RMII reference
-                clock. Internal reference clock means that the clock for
-                the RMII of ksz88x3 is provided by the ksz88x3 internally
-                and the REFCLKI pin is unconnected. For the external
-                reference clock, the clock needs to be fed back to ksz88x3
-                via REFCLKI.
-                If microchip,rmii-clk-internal is set, ksz88x3 will provide
-                rmii reference clock internally, otherwise reference clock
-                should be provided externally.
-          dependencies:
-            microchip,rmii-clk-internal: [ethernet]
+        "^(ethernet-)?ports$":
+          patternProperties:
+            "^(ethernet-)?port@[0-2]$":
+              $ref: dsa-port.yaml#
+              unevaluatedProperties: false
+              properties:
+                microchip,rmii-clk-internal:
+                  $ref: /schemas/types.yaml#/definitions/flag
+                  description:
+                    When ksz88x3 is acting as clock provier (via REFCLKO) it
+                    can select between internal and external RMII reference
+                    clock. Internal reference clock means that the clock for
+                    the RMII of ksz88x3 is provided by the ksz88x3 internally
+                    and the REFCLKI pin is unconnected. For the external
+                    reference clock, the clock needs to be fed back to ksz88x3
+                    via REFCLKI.
+                    If microchip,rmii-clk-internal is set, ksz88x3 will provide
+                    rmii reference clock internally, otherwise reference clock
+                    should be provided externally.
+              dependencies:
+                microchip,rmii-clk-internal: [ethernet]
 
 unevaluatedProperties: false
 

-- 
2.51.0

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

[Bastien Curutchet (Schneider Electric)]

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>
---
 .../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

[PATCH net-next v2 3/3] net: dsa: microchip: Set SPI as bus interface during reset for KSZ8463

[Bastien Curutchet]

At reset, the KSZ8463 uses a strap-based configuration to set SPI as
bus interface. SPI is the only bus supported by the driver. 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.

Introduce a ksz8463_configure_straps_spi() function called during the
device reset. It relies on the 'strap-rxd*-gpios' OF properties and the
'reset' pinmux configuration to enforce SPI as bus interface.

Signed-off-by: Bastien Curutchet (Schneider Electric) <bastien.curutchet@bootlin.com>
---
 drivers/net/dsa/microchip/ksz_common.c | 45 ++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 7292bfe2f7cac3a0d88bb51339cc287f56ca1d1f..ac05dd25b4863a61b15ac1131587b2b4df11ec41 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -23,6 +23,7 @@
 #include <linux/of_mdio.h>
 #include <linux/of_net.h>
 #include <linux/micrel_phy.h>
+#include <linux/pinctrl/consumer.h>
 #include <net/dsa.h>
 #include <net/ieee8021q.h>
 #include <net/pkt_cls.h>
@@ -5338,6 +5339,38 @@ static int ksz_parse_drive_strength(struct ksz_device *dev)
 	return 0;
 }
 
+static int ksz8463_configure_straps_spi(struct ksz_device *dev)
+{
+	struct pinctrl *pinctrl;
+	struct gpio_desc *rxd0;
+	struct gpio_desc *rxd1;
+
+	rxd0 = devm_gpiod_get_optional(dev->dev, "strap-rxd0", GPIOD_OUT_LOW);
+	if (IS_ERR(rxd0))
+		return PTR_ERR(rxd0);
+
+	rxd1 = devm_gpiod_get_optional(dev->dev, "strap-rxd1", GPIOD_OUT_HIGH);
+	if (IS_ERR(rxd1))
+		return PTR_ERR(rxd1);
+
+	if (!rxd0 && !rxd1)
+		return 0;
+
+	if ((rxd0 && !rxd1) || (rxd1 && !rxd0))
+		return -EINVAL;
+
+	pinctrl = devm_pinctrl_get_select(dev->dev, "reset");
+	if (IS_ERR(pinctrl))
+		return PTR_ERR(pinctrl);
+
+	return 0;
+}
+
+static int ksz8463_release_straps_spi(struct ksz_device *dev)
+{
+	return pinctrl_select_default_state(dev->dev);
+}
+
 int ksz_switch_register(struct ksz_device *dev)
 {
 	const struct ksz_chip_data *info;
@@ -5353,10 +5386,22 @@ int ksz_switch_register(struct ksz_device *dev)
 		return PTR_ERR(dev->reset_gpio);
 
 	if (dev->reset_gpio) {
+		if (of_device_is_compatible(dev->dev->of_node, "microchip,ksz8463")) {
+			ret = ksz8463_configure_straps_spi(dev);
+			if (ret)
+				return ret;
+		}
+
 		gpiod_set_value_cansleep(dev->reset_gpio, 1);
 		usleep_range(10000, 12000);
 		gpiod_set_value_cansleep(dev->reset_gpio, 0);
 		msleep(100);
+
+		if (of_device_is_compatible(dev->dev->of_node, "microchip,ksz8463")) {
+			ret = ksz8463_release_straps_spi(dev);
+			if (ret)
+				return ret;
+		}
 	}
 
 	mutex_init(&dev->dev_mutex);

-- 
2.51.0

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

[Rob Herring]

On Fri, Sep 12, 2025 at 11:09:13AM +0200, Bastien Curutchet (Schneider Electric) wrote:
> 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>
> ---
>  .../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 ]

It would be simpler to define "strap-rxd-gpios" with a length of 2 
entries:

straps-rxd-gpios:
  minItems: 2
  maxItems: 2

Rob

Re: [PATCH net-next v2 1/3] dt-bindings: net: dsa: microchip: Group if clause under allOf tag

[Rob Herring (Arm)]

On Fri, 12 Sep 2025 11:09:12 +0200, Bastien Curutchet (Schneider Electric) wrote:
> Upcoming patch adds a new if/then clause. It requires to be grouped with
> the already existing if/then clause under an 'allOf:' tag.
> 
> Move the if/then clause under the already existing 'allOf:' tag to
> prepare next patch.
> 
> Signed-off-by: Bastien Curutchet (Schneider Electric) <bastien.curutchet@bootlin.com>
> ---
>  .../devicetree/bindings/net/dsa/microchip,ksz.yaml | 68 +++++++++++-----------
>  1 file changed, 34 insertions(+), 34 deletions(-)
> 

Acked-by: Rob Herring (Arm) <robh@kernel.org>

Re: [PATCH net-next v2 3/3] net: dsa: microchip: Set SPI as bus interface during reset for KSZ8463

[Andrew Lunn]

On Fri, Sep 12, 2025 at 11:09:14AM +0200, Bastien Curutchet wrote:
> At reset, the KSZ8463 uses a strap-based configuration to set SPI as
> bus interface. SPI is the only bus supported by the driver. 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.
> 
> Introduce a ksz8463_configure_straps_spi() function called during the
> device reset. It relies on the 'strap-rxd*-gpios' OF properties and the
> 'reset' pinmux configuration to enforce SPI as bus interface.
> 
> Signed-off-by: Bastien Curutchet (Schneider Electric) <bastien.curutchet@bootlin.com>

Thanks for updating the commit messages, it is now a lot clearer why
this is needed.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew