[PATCH 0/3] gnss: ubx: updates to support the Renesas KingFisher board

[PATCH 0/3] gnss: ubx: updates to support the Renesas KingFisher board

[Wolfram Sang]

For that, we need "reset-gpio" support (patches 2+3). But first,
simplify regulator handling with a new helper (patch 1).

Changes since RFC v2:
* dropped DTS patch because the binding is clear now and we can upstream
  it separately
* added binding documentation
* rebased to 6.5-rc1


Wolfram Sang (3):
  gnss: ubx: use new helper to remove open coded regulator handling
  dt-bindings: gnss: u-blox: add "reset-gpios" binding
  gnss: ubx: add support for the reset gpio

 .../bindings/gnss/u-blox,neo-6m.yaml          |  7 ++++
 drivers/gnss/ubx.c                            | 35 ++++++++-----------
 2 files changed, 22 insertions(+), 20 deletions(-)

-- 
2.30.2

[PATCH 1/3] gnss: ubx: use new helper to remove open coded regulator handling

[Wolfram Sang]

v_bckp shall always be enabled as long as the device exists. We now have
a regulator helper for that, use it.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
 drivers/gnss/ubx.c | 26 ++++----------------------
 1 file changed, 4 insertions(+), 22 deletions(-)

diff --git a/drivers/gnss/ubx.c b/drivers/gnss/ubx.c
index c951be202ca2..9b76b101ba5e 100644
--- a/drivers/gnss/ubx.c
+++ b/drivers/gnss/ubx.c
@@ -17,7 +17,6 @@
 #include "serial.h"
 
 struct ubx_data {
-	struct regulator *v_bckp;
 	struct regulator *vcc;
 };
 
@@ -87,30 +86,16 @@ static int ubx_probe(struct serdev_device *serdev)
 		goto err_free_gserial;
 	}
 
-	data->v_bckp = devm_regulator_get_optional(&serdev->dev, "v-bckp");
-	if (IS_ERR(data->v_bckp)) {
-		ret = PTR_ERR(data->v_bckp);
-		if (ret == -ENODEV)
-			data->v_bckp = NULL;
-		else
-			goto err_free_gserial;
-	}
-
-	if (data->v_bckp) {
-		ret = regulator_enable(data->v_bckp);
-		if (ret)
-			goto err_free_gserial;
-	}
+	ret = devm_regulator_get_enable_optional(&serdev->dev, "v-bckp");
+	if (ret < 0 && ret != -ENODEV)
+		goto err_free_gserial;
 
 	ret = gnss_serial_register(gserial);
 	if (ret)
-		goto err_disable_v_bckp;
+		goto err_free_gserial;
 
 	return 0;
 
-err_disable_v_bckp:
-	if (data->v_bckp)
-		regulator_disable(data->v_bckp);
 err_free_gserial:
 	gnss_serial_free(gserial);
 
@@ -120,11 +105,8 @@ static int ubx_probe(struct serdev_device *serdev)
 static void ubx_remove(struct serdev_device *serdev)
 {
 	struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
-	struct ubx_data *data = gnss_serial_get_drvdata(gserial);
 
 	gnss_serial_deregister(gserial);
-	if (data->v_bckp)
-		regulator_disable(data->v_bckp);
 	gnss_serial_free(gserial);
 }
 
-- 
2.30.2

Re: [PATCH 1/3] gnss: ubx: use new helper to remove open coded regulator handling

[Geert Uytterhoeven]

On Wed, Jul 12, 2023 at 1:40 PM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
> v_bckp shall always be enabled as long as the device exists. We now have
> a regulator helper for that, use it.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

[PATCH 2/3] dt-bindings: gnss: u-blox: add "reset-gpios" binding

[Wolfram Sang]

Needed to enable this chip on a Renesas KingFisher board. Description
copied over from the Mediatek driver which already supports it.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
 Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml b/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
index 4835a280b3bf..8f6992b97ca6 100644
--- a/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
+++ b/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
@@ -41,6 +41,12 @@ properties:
     description: >
       Backup voltage regulator
 
+  reset-gpios:
+    maxItems: 1
+    description: >
+      An optional reset line, with names such as RESET or NRESET.
+      If the line is active low it should be flagged with GPIO_ACTIVE_LOW.
+
 required:
   - compatible
   - vcc-supply
@@ -54,5 +60,6 @@ examples:
             compatible = "u-blox,neo-8";
             v-bckp-supply = <&gnss_v_bckp_reg>;
             vcc-supply = <&gnss_vcc_reg>;
+            reset-gpios = <&gpio 1 GPIO_ACTIVE_LOW>;
         };
     };
-- 
2.30.2

Re: [PATCH 2/3] dt-bindings: gnss: u-blox: add "reset-gpios" binding

[Krzysztof Kozlowski]

On 12/07/2023 13:37, Wolfram Sang wrote:
> Needed to enable this chip on a Renesas KingFisher board. Description
> copied over from the Mediatek driver which already supports it.
> 
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
>  Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml b/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
> index 4835a280b3bf..8f6992b97ca6 100644
> --- a/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
> +++ b/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
> @@ -41,6 +41,12 @@ properties:
>      description: >
>        Backup voltage regulator
>  
> +  reset-gpios:
> +    maxItems: 1
> +    description: >
> +      An optional reset line, with names such as RESET or NRESET.
> +      If the line is active low it should be flagged with GPIO_ACTIVE_LOW.
> +
>  required:
>    - compatible
>    - vcc-supply
> @@ -54,5 +60,6 @@ examples:
>              compatible = "u-blox,neo-8";
>              v-bckp-supply = <&gnss_v_bckp_reg>;
>              vcc-supply = <&gnss_vcc_reg>;
> +            reset-gpios = <&gpio 1 GPIO_ACTIVE_LOW>;

This should complain with errors, because of missing header for the
defines, so usual disclaimer:

It does not look like you tested the bindings, at least after quick
look. Please run `make dt_binding_check` (see
Documentation/devicetree/bindings/writing-schema.rst for instructions).
Maybe you need to update your dtschema and yamllint.

Best regards,
Krzysztof

Re: [PATCH 2/3] dt-bindings: gnss: u-blox: add "reset-gpios" binding

[Geert Uytterhoeven]

Hi Wolfram,

On Wed, Jul 12, 2023 at 1:40 PM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
> Needed to enable this chip on a Renesas KingFisher board. Description
> copied over from the Mediatek driver which already supports it.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Thanks for your patch!

> --- a/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
> +++ b/Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml
> @@ -41,6 +41,12 @@ properties:
>      description: >
>        Backup voltage regulator
>
> +  reset-gpios:
> +    maxItems: 1
> +    description: >
> +      An optional reset line, with names such as RESET or NRESET.
> +      If the line is active low it should be flagged with GPIO_ACTIVE_LOW.

I think you can drop the description, as it describes only the obvious.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH 2/3] dt-bindings: gnss: u-blox: add "reset-gpios" binding

[Rob Herring]

On Wed, 12 Jul 2023 13:37:30 +0200, Wolfram Sang wrote:
> Needed to enable this chip on a Renesas KingFisher board. Description
> copied over from the Mediatek driver which already supports it.
> 
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
>  Documentation/devicetree/bindings/gnss/u-blox,neo-6m.yaml | 7 +++++++
>  1 file changed, 7 insertions(+)
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:

dtschema/dtc warnings/errors:
Error: Documentation/devicetree/bindings/gnss/u-blox,neo-6m.example.dts:23.40-41 syntax error
FATAL ERROR: Unable to parse input tree
make[2]: *** [scripts/Makefile.lib:419: Documentation/devicetree/bindings/gnss/u-blox,neo-6m.example.dtb] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [/builds/robherring/dt-review-ci/linux/Makefile:1500: dt_binding_check] Error 2
make: *** [Makefile:234: __sub-make] Error 2

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20230712113731.3306-3-wsa+renesas@sang-engineering.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

[PATCH 3/3] gnss: ubx: add support for the reset gpio

[Wolfram Sang]

Tested with a Renesas KingFisher board. Because my GNSS device is hooked
up via UART and I2C simultaneously, I could verify functionality by
opening/closing the GNSS device using UART and see if the corresponding
I2C device was visible on the bus.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
 drivers/gnss/ubx.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/gnss/ubx.c b/drivers/gnss/ubx.c
index 9b76b101ba5e..cb0612100644 100644
--- a/drivers/gnss/ubx.c
+++ b/drivers/gnss/ubx.c
@@ -7,6 +7,7 @@
 
 #include <linux/errno.h>
 #include <linux/gnss.h>
+#include <linux/gpio/consumer.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -18,6 +19,7 @@
 
 struct ubx_data {
 	struct regulator *vcc;
+	struct gpio_desc *reset_gpio;
 };
 
 static int ubx_set_active(struct gnss_serial *gserial)
@@ -29,6 +31,8 @@ static int ubx_set_active(struct gnss_serial *gserial)
 	if (ret)
 		return ret;
 
+	gpiod_set_value_cansleep(data->reset_gpio, 0);
+
 	return 0;
 }
 
@@ -41,6 +45,8 @@ static int ubx_set_standby(struct gnss_serial *gserial)
 	if (ret)
 		return ret;
 
+	gpiod_set_value_cansleep(data->reset_gpio, 1);
+
 	return 0;
 }
 
@@ -90,6 +96,13 @@ static int ubx_probe(struct serdev_device *serdev)
 	if (ret < 0 && ret != -ENODEV)
 		goto err_free_gserial;
 
+	/* Start with reset asserted (GPIO must be active low!) */
+	data->reset_gpio = devm_gpiod_get_optional(&serdev->dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(data->reset_gpio)) {
+		ret = PTR_ERR(data->reset_gpio);
+		goto err_free_gserial;
+	}
+
 	ret = gnss_serial_register(gserial);
 	if (ret)
 		goto err_free_gserial;
-- 
2.30.2

Re: [PATCH 3/3] gnss: ubx: add support for the reset gpio

[Geert Uytterhoeven]

Hi Wolfram,

On Wed, Jul 12, 2023 at 1:40 PM Wolfram Sang
<wsa+renesas@sang-engineering.com> wrote:
> Tested with a Renesas KingFisher board. Because my GNSS device is hooked
> up via UART and I2C simultaneously, I could verify functionality by
> opening/closing the GNSS device using UART and see if the corresponding
> I2C device was visible on the bus.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Thanks for your patch!

> --- a/drivers/gnss/ubx.c
> +++ b/drivers/gnss/ubx.c
> @@ -29,6 +31,8 @@ static int ubx_set_active(struct gnss_serial *gserial)
>         if (ret)
>                 return ret;
>
> +       gpiod_set_value_cansleep(data->reset_gpio, 0);
> +
>         return 0;
>  }
>
> @@ -41,6 +45,8 @@ static int ubx_set_standby(struct gnss_serial *gserial)
>         if (ret)
>                 return ret;
>
> +       gpiod_set_value_cansleep(data->reset_gpio, 1);

Please assert reset before disabling the regulator, for symmetry
with ubx_set_active().

> +
>         return 0;
>  }
>
> @@ -90,6 +96,13 @@ static int ubx_probe(struct serdev_device *serdev)
>         if (ret < 0 && ret != -ENODEV)
>                 goto err_free_gserial;
>
> +       /* Start with reset asserted (GPIO must be active low!) */

Does it have to be active low?
The description in your DT bindings suggest both active low and active
high are possible.

I think you just wanted to express that GPIOD_OUT_HIGH means asserted,
i.e. low for the common case of an active-low reset?

> +       data->reset_gpio = devm_gpiod_get_optional(&serdev->dev, "reset", GPIOD_OUT_HIGH);
> +       if (IS_ERR(data->reset_gpio)) {
> +               ret = PTR_ERR(data->reset_gpio);
> +               goto err_free_gserial;
> +       }
> +
>         ret = gnss_serial_register(gserial);
>         if (ret)
>                 goto err_free_gserial;

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds