[PATCH v2 0/2] Add support for safeboot pin to UBlox GNSS driver

[PATCH v2 0/2] Add support for safeboot pin to UBlox GNSS driver

[Alejandro Enrique via B4 Relay]

U-Blox 8/M8 and M9 chips have a pin to start it in safeboot mode, to
be used to recover from situations where the flash content has become
corrupted and needs to be restored. If this pin is asserted at power
up or reset, the receiver starts in safeboot mode and GNSS operation
is disabled.

If this pin is wired to a GPIO in the host it should be deasserted
before powering up or resetting the GNSS.

This series adds support for handling the safeboot pin when probing
the driver.

Signed-off-by: Alejandro Enrique <alejandroe1@geotab.com>
---
Changes in v2:
- Add if/then to dt binding to disallow safeboot-gpios property for neo-6m
- Link to v1: https://lore.kernel.org/r/20250514-ubx-safeboot-v1-0-1ae771335356@geotab.com

---
Alejandro Enrique (2):
      dt-bindings: gnss: u-blox: add "safeboot-gpios" binding
      gnss: ubx: add support for the safeboot gpio

 Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml | 20 ++++++++++++++++----
 drivers/gnss/ubx.c                                        |  8 ++++++++
 2 files changed, 24 insertions(+), 4 deletions(-)
---
base-commit: 9c32cda43eb78f78c73aee4aa344b777714e259b
change-id: 20250514-ubx-safeboot-3758f22225ec

Best regards,
-- 
Alejandro Enrique <alejandroe1@geotab.com>

[PATCH v2 1/2] dt-bindings: gnss: u-blox: add "safeboot-gpios" binding

[Alejandro Enrique via B4 Relay]

From: Alejandro Enrique <alejandroe1@geotab.com>

U-Blox 8/M8/M9 chip have a pin to start it in safeboot mode, to be
used to recover from situations where the flash content has become
corrupted and needs to be restored. Introduce a binding to support
this safeboot pin.

Signed-off-by: Alejandro Enrique <alejandroe1@geotab.com>
---
 Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml b/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
index 7d4b6d49e5eea2201ac05ba6d54b1c1721172f26..7589327a77da5c70bfebe57685e2a4bbfd95934c 100644
--- a/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
+++ b/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
@@ -6,10 +6,6 @@ $schema: http://devicetree.org/meta-schemas/core.yaml#
 
 title: U-blox GNSS Receiver
 
-allOf:
-  - $ref: gnss-common.yaml#
-  - $ref: /schemas/serial/serial-peripheral-props.yaml#
-
 maintainers:
   - Johan Hovold <johan@kernel.org>
 
@@ -32,6 +28,9 @@ properties:
   reset-gpios:
     maxItems: 1
 
+  safeboot-gpios:
+    maxItems: 1
+
   vcc-supply:
     description: >
       Main voltage regulator
@@ -49,6 +48,18 @@ required:
   - compatible
   - vcc-supply
 
+allOf:
+  - $ref: gnss-common.yaml#
+  - $ref: /schemas/serial/serial-peripheral-props.yaml#
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: u-blox,neo-6m
+    then:
+      properties:
+        safeboot-gpios: false
+
 unevaluatedProperties: false
 
 examples:
@@ -61,5 +72,6 @@ examples:
             v-bckp-supply = <&gnss_v_bckp_reg>;
             vcc-supply = <&gnss_vcc_reg>;
             reset-gpios = <&gpio 1 GPIO_ACTIVE_LOW>;
+            safeboot-gpios = <&gpio 2 GPIO_ACTIVE_LOW>;
         };
     };

-- 
2.34.1

[PATCH v2 2/2] gnss: ubx: add support for the safeboot gpio

[Alejandro Enrique via B4 Relay]

From: Alejandro Enrique <alejandroe1@geotab.com>

U-Blox 8/M8/M9 chip have a pin to start it in safeboot mode, to be
used to recover from situations where the flash content has become
corrupted and needs to be restored. If this pin is asserted at power
up/reset, the receiver starts in safeboot mode and GNSS operation is
disabled.

Deassert the safeboot pin when probing this driver.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Alejandro Enrique <alejandroe1@geotab.com>
---
 drivers/gnss/ubx.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gnss/ubx.c b/drivers/gnss/ubx.c
index 92402f6082c415c7b9051338eef5406b09e09455..1d6acace84f76f8d5d2eacdbbf5ab7a934b33486 100644
--- a/drivers/gnss/ubx.c
+++ b/drivers/gnss/ubx.c
@@ -67,6 +67,7 @@ static int ubx_probe(struct serdev_device *serdev)
 {
 	struct gnss_serial *gserial;
 	struct gpio_desc *reset;
+	struct gpio_desc *safeboot;
 	struct ubx_data *data;
 	int ret;
 
@@ -82,6 +83,13 @@ static int ubx_probe(struct serdev_device *serdev)
 
 	data = gnss_serial_get_drvdata(gserial);
 
+	/* Deassert safeboot */
+	safeboot = devm_gpiod_get_optional(&serdev->dev, "safeboot", GPIOD_OUT_LOW);
+	if (IS_ERR(safeboot)) {
+		ret = PTR_ERR(safeboot);
+		goto err_free_gserial;
+	}
+
 	data->vcc = devm_regulator_get(&serdev->dev, "vcc");
 	if (IS_ERR(data->vcc)) {
 		ret = PTR_ERR(data->vcc);

-- 
2.34.1

Re: [PATCH v2 1/2] dt-bindings: gnss: u-blox: add "safeboot-gpios" binding

[Krzysztof Kozlowski]

On 22/05/2025 18:51, Alejandro Enrique via B4 Relay wrote:
> From: Alejandro Enrique <alejandroe1@geotab.com>
> 
> U-Blox 8/M8/M9 chip have a pin to start it in safeboot mode, to be
> used to recover from situations where the flash content has become
> corrupted and needs to be restored. Introduce a binding to support
> this safeboot pin.
> 
> Signed-off-by: Alejandro Enrique <alejandroe1@geotab.com>
> ---
>  Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml | 20 +++++++++++++++



Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>


Best regards,
Krzysztof