[PATCH v3 0/7] gpio: introduce a gpio driver for SCMI

[PATCH v3 0/7] gpio: introduce a gpio driver for SCMI

[Dan Carpenter]

This basically abandons my earlier attempts and goes back to Takahiro
Akashi's driver.  Here is the link to Takahiro's patchset:

https://lore.kernel.org/all/20231005025843.508689-1-takahiro.akashi@linaro.org/

In the review comments, to that patchset we had discussed putting the
gpio section inside the pinctrl section.  The ordering problems are a
bit tricky because you want the pinctrl driver to finish probing before
you start probing the gpio driver.  To me it seems nicer to put the
pinctrl things such as pinmuxing in the pinctrl block and the gpio things
in the gpio block.

I updated Takahiro's patch to work on current kernels.  I've had added a
few other patches to make things work on current kernels.  The most
noteworthy change is that instead of calculating the ngpios, I changed
it so you have to specify the ngpios in the device tree.

I updated the device tree spec file to address review comments.  I
changed the compatible to scmi-pinctrl-gpio.  I also updated the
examples to show how pinmuxing works.  I didn't know how to include all
the potential GPIO configuration options so I set
"additionalProperties: true".  Hopefully, that's okay.

AKASHI Takahiro (3):
  pinctrl: introduce pinctrl_gpio_get_config()
  dt-bindings: gpio: Add bindings for pinctrl based generic gpio driver
  gpio: add pinctrl based generic gpio driver

Dan Carpenter (4):
  pinctrl: scmi: Add SCMI_PIN_INPUT_VALUE
  pinctrl: Delete PIN_CONFIG_OUTPUT_IMPEDANCE_OHMS support
  pinctrl-scmi: ignore PIN_CONFIG_PERSIST_STATE
  arm_scmi: pinctrl: allow PINCTRL_REQUEST to return EOPNOTSUPP

 .../bindings/gpio/pin-control-gpio.yaml       |  70 ++++++++++
 drivers/firmware/arm_scmi/pinctrl.c           |   2 +
 drivers/gpio/Kconfig                          |   7 +
 drivers/gpio/Makefile                         |   1 +
 drivers/gpio/gpio-by-pinctrl.c                | 124 ++++++++++++++++++
 drivers/pinctrl/core.c                        |  30 +++++
 drivers/pinctrl/pinctrl-scmi.c                |  46 +++++--
 include/linux/pinctrl/consumer.h              |   9 ++
 8 files changed, 276 insertions(+), 13 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
 create mode 100644 drivers/gpio/gpio-by-pinctrl.c

-- 
2.51.0

[PATCH v3 6/7] dt-bindings: gpio: Add bindings for pinctrl based generic gpio driver

[Dan Carpenter]

From: AKASHI Takahiro <takahiro.akashi@linaro.org>

Add a dt binding for the gpio-by-pinctrl driver.  The driver is used
for doing GPIO over the SCMI pinctrl protocol.  There are a few
mandatory properties such as gpio-ranges and ngpios, but it's not
mandatory to specify the pin-mux.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 .../bindings/gpio/pin-control-gpio.yaml       | 70 +++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml

diff --git a/Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml b/Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
new file mode 100644
index 000000000000..81c68579df6e
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/gpio/pin-control-gpio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Pin control based generic GPIO controller
+
+description:
+  The pin control-based GPIO will facilitate a pin controller's ability
+  to drive electric lines high/low and other generic properties of a
+  pin controller to perform general-purpose one-bit binary I/O.
+
+maintainers:
+  - Dan Carpenter <dan.carpenter@linaro.og>
+
+properties:
+  compatible:
+    const: scmi-pinctrl-gpio
+
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 2
+
+  gpio-ranges: true
+
+  ngpios: true
+
+patternProperties:
+  "^.+-hog(-[0-9]+)?$":
+    type: object
+
+    required:
+      - gpio-hog
+
+required:
+  - compatible
+  - gpio-controller
+  - "#gpio-cells"
+  - gpio-ranges
+  - ngpios
+
+additionalProperties: true
+
+examples:
+  - |
+    gpio1 {
+        compatible = "scmi-pinctrl-gpio";
+        gpio-controller;
+        #gpio-cells = <2>;
+        ngpios = <10>;
+        gpio-ranges = <&scmi_pinctrl 0 8 4>,
+                      <&scmi_pinctrl 4 12 1>,
+                      <&scmi_pinctrl 5 15 1>,
+                      <&scmi_pinctrl 6 17 4>;
+        pinctrl-names = "default";
+        pinctrl-0 = <&i2c2_pins>;
+    };
+
+    gpio2 {
+        compatible = "scmi-pinctrl-gpio";
+        gpio-controller;
+        #gpio-cells = <2>;
+        ngpios = <3>;
+        gpio-line-names = "gpio_5_17", "gpio_5_20", "gpio_5_22", "gpio_2_1";
+        gpio-ranges = <&scmi_pinctrl 0 30 4>;
+        pinctrl-names = "default";
+        pinctrl-0 = <&keys_pins>;
+    };
-- 
2.51.0

Re: [PATCH v3 6/7] dt-bindings: gpio: Add bindings for pinctrl based generic gpio driver

[Linus Walleij]

On Wed, Mar 11, 2026 at 8:39 PM Dan Carpenter <dan.carpenter@linaro.org> wrote:

> From: AKASHI Takahiro <takahiro.akashi@linaro.org>
>
> Add a dt binding for the gpio-by-pinctrl driver.  The driver is used
> for doing GPIO over the SCMI pinctrl protocol.  There are a few
> mandatory properties such as gpio-ranges and ngpios, but it's not
> mandatory to specify the pin-mux.
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>

I think Takashi's original idea is sound now that we clarified
the level read/set semantics!
Reviewed-by: Linus Walleij <linusw@kernel.org>

Yours,
Linus Walleij

Re: [PATCH v3 6/7] dt-bindings: gpio: Add bindings for pinctrl based generic gpio driver

[Rob Herring]

On Wed, Mar 11, 2026 at 10:39:17PM +0300, Dan Carpenter wrote:
> From: AKASHI Takahiro <takahiro.akashi@linaro.org>
> 
> Add a dt binding for the gpio-by-pinctrl driver.  The driver is used
> for doing GPIO over the SCMI pinctrl protocol.  There are a few
> mandatory properties such as gpio-ranges and ngpios, but it's not
> mandatory to specify the pin-mux.
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> ---
>  .../bindings/gpio/pin-control-gpio.yaml       | 70 +++++++++++++++++++
>  1 file changed, 70 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
> 
> diff --git a/Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml b/Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
> new file mode 100644
> index 000000000000..81c68579df6e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
> @@ -0,0 +1,70 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/gpio/pin-control-gpio.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Pin control based generic GPIO controller
> +
> +description:
> +  The pin control-based GPIO will facilitate a pin controller's ability
> +  to drive electric lines high/low and other generic properties of a
> +  pin controller to perform general-purpose one-bit binary I/O.
> +
> +maintainers:
> +  - Dan Carpenter <dan.carpenter@linaro.og>
> +
> +properties:
> +  compatible:
> +    const: scmi-pinctrl-gpio
> +
> +  gpio-controller: true
> +
> +  "#gpio-cells":
> +    const: 2
> +
> +  gpio-ranges: true
> +
> +  ngpios: true
> +
> +patternProperties:
> +  "^.+-hog(-[0-9]+)?$":
> +    type: object
> +
> +    required:
> +      - gpio-hog
> +
> +required:
> +  - compatible
> +  - gpio-controller
> +  - "#gpio-cells"
> +  - gpio-ranges
> +  - ngpios
> +
> +additionalProperties: true

That's only valid for common (incomplete) schemas. It must be false.

> +
> +examples:
> +  - |
> +    gpio1 {
> +        compatible = "scmi-pinctrl-gpio";
> +        gpio-controller;
> +        #gpio-cells = <2>;
> +        ngpios = <10>;
> +        gpio-ranges = <&scmi_pinctrl 0 8 4>,
> +                      <&scmi_pinctrl 4 12 1>,
> +                      <&scmi_pinctrl 5 15 1>,
> +                      <&scmi_pinctrl 6 17 4>;
> +        pinctrl-names = "default";
> +        pinctrl-0 = <&i2c2_pins>;
> +    };
> +
> +    gpio2 {
> +        compatible = "scmi-pinctrl-gpio";
> +        gpio-controller;
> +        #gpio-cells = <2>;
> +        ngpios = <3>;
> +        gpio-line-names = "gpio_5_17", "gpio_5_20", "gpio_5_22", "gpio_2_1";
> +        gpio-ranges = <&scmi_pinctrl 0 30 4>;
> +        pinctrl-names = "default";
> +        pinctrl-0 = <&keys_pins>;
> +    };

I think 1 example is enough.

> -- 
> 2.51.0
>