[PATCH v4 0/7] gpio: add pinctrl based generic gpio driver

[PATCH v4 0/7] gpio: add pinctrl based generic gpio driver

[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/

v4: Addressed Andy's comments about kernel-doc
    Addressed Rob's comments on the spec file
v3: Forward ported Takahiro's patches and added some fixes ups to make
    it work on current kernels.

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       |  59 +++++++++
 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                        |  31 +++++
 drivers/pinctrl/pinctrl-scmi.c                |  46 +++++--
 include/linux/pinctrl/consumer.h              |   9 ++
 8 files changed, 266 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 v4 1/7] pinctrl: introduce pinctrl_gpio_get_config()

[Dan Carpenter]

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

This is a counterpart of pinctrl_gpio_set_config(), which will be used
to implement the ->get() interface in a GPIO driver for SCMI.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
---
v4: Fix kernel-doc (Andy)

 drivers/pinctrl/core.c           | 31 +++++++++++++++++++++++++++++++
 include/linux/pinctrl/consumer.h |  9 +++++++++
 2 files changed, 40 insertions(+)

diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index 2edc9bdad183..c471f3fbd035 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -30,6 +30,7 @@
 #include <linux/pinctrl/consumer.h>
 #include <linux/pinctrl/devinfo.h>
 #include <linux/pinctrl/machine.h>
+#include <linux/pinctrl/pinconf.h>
 #include <linux/pinctrl/pinctrl.h>
 
 #include "core.h"
@@ -938,6 +939,36 @@ int pinctrl_gpio_set_config(struct gpio_chip *gc, unsigned int offset,
 }
 EXPORT_SYMBOL_GPL(pinctrl_gpio_set_config);
 
+/**
+ * pinctrl_gpio_get_config() - Get the config for a given GPIO pin
+ * @gc: GPIO chip structure from the GPIO subsystem
+ * @offset: hardware offset of the GPIO relative to the controller
+ * @config: the configuration to query.  On success it holds the result
+ * Return: 0 on success, negative errno otherwise
+ */
+int pinctrl_gpio_get_config(struct gpio_chip *gc, unsigned int offset, unsigned long *config)
+{
+	struct pinctrl_gpio_range *range;
+	struct pinctrl_dev *pctldev;
+	int ret, pin;
+
+	ret = pinctrl_get_device_gpio_range(gc, offset, &pctldev, &range);
+	if (ret)
+		return ret;
+
+	mutex_lock(&pctldev->mutex);
+	pin = gpio_to_pin(range, gc, offset);
+	ret = pin_config_get_for_pin(pctldev, pin, config);
+	mutex_unlock(&pctldev->mutex);
+
+	if (ret)
+		return ret;
+
+	*config = pinconf_to_config_argument(*config);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(pinctrl_gpio_get_config);
+
 static struct pinctrl_state *find_state(struct pinctrl *p,
 					const char *name)
 {
diff --git a/include/linux/pinctrl/consumer.h b/include/linux/pinctrl/consumer.h
index 63ce16191eb9..11b8f0b8da0c 100644
--- a/include/linux/pinctrl/consumer.h
+++ b/include/linux/pinctrl/consumer.h
@@ -35,6 +35,8 @@ int pinctrl_gpio_direction_output(struct gpio_chip *gc,
 				  unsigned int offset);
 int pinctrl_gpio_set_config(struct gpio_chip *gc, unsigned int offset,
 				unsigned long config);
+int pinctrl_gpio_get_config(struct gpio_chip *gc, unsigned int offset,
+			    unsigned long *config);
 
 struct pinctrl * __must_check pinctrl_get(struct device *dev);
 void pinctrl_put(struct pinctrl *p);
@@ -101,6 +103,13 @@ pinctrl_gpio_direction_output(struct gpio_chip *gc, unsigned int offset)
 	return 0;
 }
 
+static inline int
+pinctrl_gpio_get_config(struct gpio_chip *gc, unsigned int offset,
+			unsigned long *config)
+{
+	return 0;
+}
+
 static inline int
 pinctrl_gpio_set_config(struct gpio_chip *gc, unsigned int offset,
 			    unsigned long config)
-- 
2.51.0

Re: [PATCH v4 1/7] pinctrl: introduce pinctrl_gpio_get_config()

[Andy Shevchenko]

On Tue, Mar 17, 2026 at 05:40:20PM +0300, Dan Carpenter wrote:

> This is a counterpart of pinctrl_gpio_set_config(), which will be used
> to implement the ->get() interface in a GPIO driver for SCMI.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>

-- 
With Best Regards,
Andy Shevchenko

[PATCH v4 2/7] pinctrl: scmi: Add SCMI_PIN_INPUT_VALUE

[Dan Carpenter]

The PIN_CONFIG_LEVEL parameter represents the value of the pin, whether
reading or writing to the pin.  In SCMI, the parameter is represented by
two different values SCMI_PIN_OUTPUT_VALUE for writing to a pin and
SCMI_PIN_INPUT_VALUE for reading.  The current code translates
PIN_CONFIG_LEVEL as SCMI_PIN_OUTPUT_VALUE (writing).

Add a function to translate it to either INPUT or OUTPUT depending on
whether it is called from a _get or _set() operation.

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Acked-by: Sudeep Holla <sudeep.holla@kernel.org>
---
 drivers/pinctrl/pinctrl-scmi.c | 33 ++++++++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/drivers/pinctrl/pinctrl-scmi.c b/drivers/pinctrl/pinctrl-scmi.c
index f4f296e07be5..5d347e6b2e4c 100644
--- a/drivers/pinctrl/pinctrl-scmi.c
+++ b/drivers/pinctrl/pinctrl-scmi.c
@@ -251,9 +251,6 @@ static int pinctrl_scmi_map_pinconf_type(enum pin_config_param param,
 	case PIN_CONFIG_MODE_LOW_POWER:
 		*type = SCMI_PIN_LOW_POWER_MODE;
 		break;
-	case PIN_CONFIG_LEVEL:
-		*type = SCMI_PIN_OUTPUT_VALUE;
-		break;
 	case PIN_CONFIG_OUTPUT_ENABLE:
 		*type = SCMI_PIN_OUTPUT_MODE;
 		break;
@@ -276,6 +273,28 @@ static int pinctrl_scmi_map_pinconf_type(enum pin_config_param param,
 	return 0;
 }
 
+static int pinctrl_scmi_map_pinconf_type_get(enum pin_config_param param,
+					     enum scmi_pinctrl_conf_type *type)
+{
+	if (param == PIN_CONFIG_LEVEL) {
+		*type = SCMI_PIN_INPUT_VALUE;
+		return 0;
+	}
+
+	return pinctrl_scmi_map_pinconf_type(param, type);
+}
+
+static int pinctrl_scmi_map_pinconf_type_set(enum pin_config_param param,
+					     enum scmi_pinctrl_conf_type *type)
+{
+	if (param == PIN_CONFIG_LEVEL) {
+		*type = SCMI_PIN_OUTPUT_VALUE;
+		return 0;
+	}
+
+	return pinctrl_scmi_map_pinconf_type(param, type);
+}
+
 static int pinctrl_scmi_pinconf_get(struct pinctrl_dev *pctldev,
 				    unsigned int pin, unsigned long *config)
 {
@@ -290,7 +309,7 @@ static int pinctrl_scmi_pinconf_get(struct pinctrl_dev *pctldev,
 
 	config_type = pinconf_to_config_param(*config);
 
-	ret = pinctrl_scmi_map_pinconf_type(config_type, &type);
+	ret = pinctrl_scmi_map_pinconf_type_get(config_type, &type);
 	if (ret)
 		return ret;
 
@@ -363,7 +382,7 @@ static int pinctrl_scmi_pinconf_set(struct pinctrl_dev *pctldev,
 
 	for (i = 0; i < num_configs; i++) {
 		param = pinconf_to_config_param(configs[i]);
-		ret = pinctrl_scmi_map_pinconf_type(param, &p_config_type[i]);
+		ret = pinctrl_scmi_map_pinconf_type_set(param, &p_config_type[i]);
 		if (ret) {
 			dev_err(pmx->dev, "Error map pinconf_type %d\n", ret);
 			goto free_config;
@@ -405,7 +424,7 @@ static int pinctrl_scmi_pinconf_group_set(struct pinctrl_dev *pctldev,
 
 	for (i = 0; i < num_configs; i++) {
 		param = pinconf_to_config_param(configs[i]);
-		ret = pinctrl_scmi_map_pinconf_type(param, &p_config_type[i]);
+		ret = pinctrl_scmi_map_pinconf_type_set(param, &p_config_type[i]);
 		if (ret) {
 			dev_err(pmx->dev, "Error map pinconf_type %d\n", ret);
 			goto free_config;
@@ -440,7 +459,7 @@ static int pinctrl_scmi_pinconf_group_get(struct pinctrl_dev *pctldev,
 		return -EINVAL;
 
 	config_type = pinconf_to_config_param(*config);
-	ret = pinctrl_scmi_map_pinconf_type(config_type, &type);
+	ret = pinctrl_scmi_map_pinconf_type_get(config_type, &type);
 	if (ret) {
 		dev_err(pmx->dev, "Error map pinconf_type %d\n", ret);
 		return ret;
-- 
2.51.0

Re: [PATCH v4 2/7] pinctrl: scmi: Add SCMI_PIN_INPUT_VALUE

[Andy Shevchenko]

On Tue, Mar 17, 2026 at 05:40:27PM +0300, Dan Carpenter wrote:
> The PIN_CONFIG_LEVEL parameter represents the value of the pin, whether
> reading or writing to the pin.  In SCMI, the parameter is represented by
> two different values SCMI_PIN_OUTPUT_VALUE for writing to a pin and
> SCMI_PIN_INPUT_VALUE for reading.  The current code translates
> PIN_CONFIG_LEVEL as SCMI_PIN_OUTPUT_VALUE (writing).
> 
> Add a function to translate it to either INPUT or OUTPUT depending on
> whether it is called from a _get or _set() operation.

In three consecutive patches against the same file you have three (!) different
prefixes. Please, align with what is being used most in the driver and/or subsystem
(the driver seems has no consensus with itself, so subsystem then, something like
 "pinctrl: scmi: ").

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v4 2/7] pinctrl: scmi: Add SCMI_PIN_INPUT_VALUE

[Dan Carpenter]

On Tue, Mar 17, 2026 at 05:38:36PM +0200, Andy Shevchenko wrote:
> On Tue, Mar 17, 2026 at 05:40:27PM +0300, Dan Carpenter wrote:
> > The PIN_CONFIG_LEVEL parameter represents the value of the pin, whether
> > reading or writing to the pin.  In SCMI, the parameter is represented by
> > two different values SCMI_PIN_OUTPUT_VALUE for writing to a pin and
> > SCMI_PIN_INPUT_VALUE for reading.  The current code translates
> > PIN_CONFIG_LEVEL as SCMI_PIN_OUTPUT_VALUE (writing).
> > 
> > Add a function to translate it to either INPUT or OUTPUT depending on
> > whether it is called from a _get or _set() operation.
> 
> In three consecutive patches against the same file you have three (!) different
> prefixes. Please, align with what is being used most in the driver and/or subsystem
> (the driver seems has no consensus with itself, so subsystem then, something like
>  "pinctrl: scmi: ").

Oops.  Crud.  You're right.

regards,
dan carpenter

[PATCH v4 3/7] pinctrl: Delete PIN_CONFIG_OUTPUT_IMPEDANCE_OHMS support

[Dan Carpenter]

The argument for PIN_CONFIG_OUTPUT_IMPEDANCE_OHMS is supposed to
be expressed in terms of ohms.  But the pinctrl-scmi driver was
implementing it the same as PIN_CONFIG_OUTPUT and writing either a
zero or one to the pin.

The SCMI protocol doesn't have an support configuration type so just
delete this code instead of replacing it.

Cc: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
---
 drivers/pinctrl/pinctrl-scmi.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/pinctrl/pinctrl-scmi.c b/drivers/pinctrl/pinctrl-scmi.c
index 5d347e6b2e4c..de8c113bc61d 100644
--- a/drivers/pinctrl/pinctrl-scmi.c
+++ b/drivers/pinctrl/pinctrl-scmi.c
@@ -254,9 +254,6 @@ static int pinctrl_scmi_map_pinconf_type(enum pin_config_param param,
 	case PIN_CONFIG_OUTPUT_ENABLE:
 		*type = SCMI_PIN_OUTPUT_MODE;
 		break;
-	case PIN_CONFIG_OUTPUT_IMPEDANCE_OHMS:
-		*type = SCMI_PIN_OUTPUT_VALUE;
-		break;
 	case PIN_CONFIG_POWER_SOURCE:
 		*type = SCMI_PIN_POWER_SOURCE;
 		break;
-- 
2.51.0

[PATCH v4 4/7] pinctrl-scmi: ignore PIN_CONFIG_PERSIST_STATE

[Dan Carpenter]

The PIN_CONFIG_PERSIST_STATE setting ensures that the pin state persists
across a sleep or controller reset.  The SCMI spec does not have an
equivalent command to this so just ignore it.

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
---
 drivers/pinctrl/pinctrl-scmi.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/pinctrl/pinctrl-scmi.c b/drivers/pinctrl/pinctrl-scmi.c
index de8c113bc61d..f22be6b7b82a 100644
--- a/drivers/pinctrl/pinctrl-scmi.c
+++ b/drivers/pinctrl/pinctrl-scmi.c
@@ -361,7 +361,7 @@ static int pinctrl_scmi_pinconf_set(struct pinctrl_dev *pctldev,
 				    unsigned long *configs,
 				    unsigned int num_configs)
 {
-	int i, ret;
+	int i, cnt, ret;
 	struct scmi_pinctrl *pmx = pinctrl_dev_get_drvdata(pctldev);
 	enum scmi_pinctrl_conf_type config_type[SCMI_NUM_CONFIGS];
 	u32 config_value[SCMI_NUM_CONFIGS];
@@ -377,17 +377,21 @@ static int pinctrl_scmi_pinconf_set(struct pinctrl_dev *pctldev,
 	if (ret)
 		return ret;
 
+	cnt = 0;
 	for (i = 0; i < num_configs; i++) {
 		param = pinconf_to_config_param(configs[i]);
-		ret = pinctrl_scmi_map_pinconf_type_set(param, &p_config_type[i]);
+		if (param == PIN_CONFIG_PERSIST_STATE)
+			continue;
+		ret = pinctrl_scmi_map_pinconf_type_set(param, &p_config_type[cnt]);
 		if (ret) {
 			dev_err(pmx->dev, "Error map pinconf_type %d\n", ret);
 			goto free_config;
 		}
-		p_config_value[i] = pinconf_to_config_argument(configs[i]);
+		p_config_value[cnt] = pinconf_to_config_argument(configs[i]);
+		cnt++;
 	}
 
-	ret = pinctrl_ops->settings_conf(pmx->ph, pin, PIN_TYPE, num_configs,
+	ret = pinctrl_ops->settings_conf(pmx->ph, pin, PIN_TYPE, cnt,
 					 p_config_type,  p_config_value);
 	if (ret)
 		dev_err(pmx->dev, "Error parsing config %d\n", ret);
-- 
2.51.0

[PATCH v4 5/7] arm_scmi: pinctrl: allow PINCTRL_REQUEST to return EOPNOTSUPP

[Dan Carpenter]

The SCMI protocol specification says that the PINCTRL_REQUEST and
PINCTRL_RELEASE commands are optional.  So if the SCMI server returns
-EOPNOTSUPP, then treat that as success and continue.

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Reviewed-by: Sudeep Holla <sudeep.holla@kernel.org>
---
 drivers/firmware/arm_scmi/pinctrl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/firmware/arm_scmi/pinctrl.c b/drivers/firmware/arm_scmi/pinctrl.c
index a020e23d7c49..42cb1aef1fe1 100644
--- a/drivers/firmware/arm_scmi/pinctrl.c
+++ b/drivers/firmware/arm_scmi/pinctrl.c
@@ -578,6 +578,8 @@ static int scmi_pinctrl_request_free(const struct scmi_protocol_handle *ph,
 	tx->flags = cpu_to_le32(type);
 
 	ret = ph->xops->do_xfer(ph, t);
+	if (ret == -EOPNOTSUPP)
+		ret = 0;
 	ph->xops->xfer_put(ph, t);
 
 	return ret;
-- 
2.51.0

Re: [PATCH v4 5/7] arm_scmi: pinctrl: allow PINCTRL_REQUEST to return EOPNOTSUPP

[Cristian Marussi]

On Tue, Mar 17, 2026 at 05:40:50PM +0300, Dan Carpenter wrote:
> The SCMI protocol specification says that the PINCTRL_REQUEST and
> PINCTRL_RELEASE commands are optional.  So if the SCMI server returns
> -EOPNOTSUPP, then treat that as success and continue.

Hi

a nitpick, this should be

	firmware: arm_scmi: Allow PINCTRL_REQUEST to return EOPNOTSUPP

Thanks,
Cristian

> 
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> Reviewed-by: Linus Walleij <linusw@kernel.org>
> Reviewed-by: Sudeep Holla <sudeep.holla@kernel.org>
> ---
>  drivers/firmware/arm_scmi/pinctrl.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/firmware/arm_scmi/pinctrl.c b/drivers/firmware/arm_scmi/pinctrl.c
> index a020e23d7c49..42cb1aef1fe1 100644
> --- a/drivers/firmware/arm_scmi/pinctrl.c
> +++ b/drivers/firmware/arm_scmi/pinctrl.c
> @@ -578,6 +578,8 @@ static int scmi_pinctrl_request_free(const struct scmi_protocol_handle *ph,
>  	tx->flags = cpu_to_le32(type);
>  
>  	ret = ph->xops->do_xfer(ph, t);
> +	if (ret == -EOPNOTSUPP)
> +		ret = 0;
>  	ph->xops->xfer_put(ph, t);
>  
>  	return ret;
> -- 
> 2.51.0
> 

[PATCH v4 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>
Reviewed-by: Linus Walleij <linusw@kernel.org>
---
v4: Changed additionalProperties: true to false.

    My concern here was that there might be a lot of gpio properties
    which I wasn't familiar with.  To check I did:
        grep :$ Documentation/devicetree/bindings/gpio/* | \
          cut -d : -f 2- | perl -ne 's/[\       ]*//g; print "$_\n"' | \
          sort | uniq -c
    The only property that I decided to add was gpio-line-names.

    Deleted the extra bonus example.

 .../bindings/gpio/pin-control-gpio.yaml       | 59 +++++++++++++++++++
 1 file changed, 59 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..ebc3fdd039fd
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
@@ -0,0 +1,59 @@
+# 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-line-names: true
+
+  gpio-ranges: true
+
+  ngpios: true
+
+patternProperties:
+  "^.+-hog(-[0-9]+)?$":
+    type: object
+
+    required:
+      - gpio-hog
+
+required:
+  - compatible
+  - gpio-controller
+  - "#gpio-cells"
+  - gpio-ranges
+  - ngpios
+
+additionalProperties: false
+
+examples:
+  - |
+    gpio {
+        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 v4 6/7] dt-bindings: gpio: Add bindings for pinctrl based generic gpio driver

[Krzysztof Kozlowski]

On Tue, Mar 17, 2026 at 05:40:57PM +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

Drop all references to the driver. Describe the
device/hardware/firmware/interface, not driver. Same for subject.

> 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.

There is no such thing there as pin-mux, so I don't understand above
sentence.

Describe the hardware/firmware/interface, not the patch, because we
easily see which properties are mandatory. Schema tells that.

> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> Reviewed-by: Linus Walleij <linusw@kernel.org>

A nit, subject: drop second/last, redundant "bindings for". The
"dt-bindings" prefix is already stating that these are bindings.
See also:
https://elixir.bootlin.com/linux/v6.17-rc3/source/Documentation/devicetree/bindings/submitting-patches.rst#L18

> ---
> v4: Changed additionalProperties: true to false.
> 
>     My concern here was that there might be a lot of gpio properties
>     which I wasn't familiar with.  To check I did:
>         grep :$ Documentation/devicetree/bindings/gpio/* | \
>           cut -d : -f 2- | perl -ne 's/[\       ]*//g; print "$_\n"' | \
>           sort | uniq -c
>     The only property that I decided to add was gpio-line-names.
> 
>     Deleted the extra bonus example.
> 
>  .../bindings/gpio/pin-control-gpio.yaml       | 59 +++++++++++++++++++
>  1 file changed, 59 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
> 
> diff --git a/Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml b/Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
> new file mode 100644
> index 000000000000..ebc3fdd039fd
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/gpio/pin-control-gpio.yaml
> @@ -0,0 +1,59 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/gpio/pin-control-gpio.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Pin control based generic GPIO controller
> +
> +description:
> +  The pin control-based GPIO will facilitate a pin controller's ability
> +  to drive electric lines high/low and other generic properties of a
> +  pin controller to perform general-purpose one-bit binary I/O.
> +
> +maintainers:
> +  - Dan Carpenter <dan.carpenter@linaro.og>
> +
> +properties:
> +  compatible:
> +    const: scmi-pinctrl-gpio
> +
> +  gpio-controller: true
> +
> +  "#gpio-cells":
> +    const: 2
> +
> +  gpio-line-names: true
> +
> +  gpio-ranges: true
> +
> +  ngpios: true
> +
> +patternProperties:
> +  "^.+-hog(-[0-9]+)?$":
> +    type: object
> +
> +    required:
> +      - gpio-hog
> +
> +required:
> +  - compatible
> +  - gpio-controller
> +  - "#gpio-cells"
> +  - gpio-ranges
> +  - ngpios
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    gpio {
> +        compatible = "scmi-pinctrl-gpio";
> +        gpio-controller;
> +        #gpio-cells = <2>;
> +        ngpios = <3>;

Three pins here

> +        gpio-line-names = "gpio_5_17", "gpio_5_20", "gpio_5_22", "gpio_2_1";

... four here

> +        gpio-ranges = <&scmi_pinctrl 0 30 4>;

... and four here, so it feels inconsistent. I guess ngpios = 4?

Best regards,
Krzysztof

[PATCH v4 7/7] gpio: add pinctrl based generic gpio driver

[Dan Carpenter]

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

The ARM SCMI pinctrl protocol allows GPIO access.  Instead of creating
a new SCMI gpio driver, this driver is a generic GPIO driver that uses
standard pinctrl interfaces.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
 drivers/gpio/Kconfig           |   7 ++
 drivers/gpio/Makefile          |   1 +
 drivers/gpio/gpio-by-pinctrl.c | 124 +++++++++++++++++++++++++++++++++
 3 files changed, 132 insertions(+)
 create mode 100644 drivers/gpio/gpio-by-pinctrl.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index b45fb799e36c..4c8d2589c412 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -246,6 +246,13 @@ config GPIO_BRCMSTB
 	help
 	  Say yes here to enable GPIO support for Broadcom STB (BCM7XXX) SoCs.
 
+config GPIO_BY_PINCTRL
+	tristate "GPIO support based on a pure pin control backend"
+	depends on GPIOLIB
+	help
+	  Select this option to support GPIO devices based solely on pin
+	  control.  This is used to do GPIO over the ARM SCMI protocol.
+
 config GPIO_CADENCE
 	tristate "Cadence GPIO support"
 	depends on OF_GPIO
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index c05f7d795c43..20d4a57afdaa 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -51,6 +51,7 @@ obj-$(CONFIG_GPIO_BD9571MWV)		+= gpio-bd9571mwv.o
 obj-$(CONFIG_GPIO_BLZP1600)		+= gpio-blzp1600.o
 obj-$(CONFIG_GPIO_BRCMSTB)		+= gpio-brcmstb.o
 obj-$(CONFIG_GPIO_BT8XX)		+= gpio-bt8xx.o
+obj-$(CONFIG_GPIO_BY_PINCTRL)		+= gpio-by-pinctrl.o
 obj-$(CONFIG_GPIO_CADENCE)		+= gpio-cadence.o
 obj-$(CONFIG_GPIO_CGBC)			+= gpio-cgbc.o
 obj-$(CONFIG_GPIO_CLPS711X)		+= gpio-clps711x.o
diff --git a/drivers/gpio/gpio-by-pinctrl.c b/drivers/gpio/gpio-by-pinctrl.c
new file mode 100644
index 000000000000..51d99723d3ca
--- /dev/null
+++ b/drivers/gpio/gpio-by-pinctrl.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (C) 2023 Linaro Inc.
+//   Author: AKASHI takahiro <takahiro.akashi@linaro.org>
+
+#include <linux/gpio/driver.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include "gpiolib.h"
+
+struct pin_control_gpio_priv {
+	struct gpio_chip chip;
+};
+
+static int pin_control_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+	unsigned long config;
+	bool in, out;
+	int ret;
+
+	config = PIN_CONFIG_INPUT_ENABLE;
+	ret = pinctrl_gpio_get_config(gc, offset, &config);
+	if (ret)
+		return ret;
+	in = config;
+
+	config = PIN_CONFIG_OUTPUT_ENABLE;
+	ret = pinctrl_gpio_get_config(gc, offset, &config);
+	if (ret)
+		return ret;
+	out = config;
+
+	/* Consistency check - in theory both can be enabled! */
+	if (in && !out)
+		return GPIO_LINE_DIRECTION_IN;
+	if (!in && out)
+		return GPIO_LINE_DIRECTION_OUT;
+
+	return -EINVAL;
+}
+
+static int pin_control_gpio_direction_output(struct gpio_chip *chip,
+					     unsigned int offset, int val)
+{
+	return pinctrl_gpio_direction_output(chip, offset);
+}
+
+static int pin_control_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	unsigned long config;
+	int ret;
+
+	config = PIN_CONFIG_LEVEL;
+	ret = pinctrl_gpio_get_config(chip, offset, &config);
+	if (ret)
+		return ret;
+
+	return !!config;
+}
+
+static int pin_control_gpio_set(struct gpio_chip *chip, unsigned int offset,
+				int val)
+{
+	unsigned long config;
+
+	config = PIN_CONF_PACKED(PIN_CONFIG_LEVEL, val);
+	return pinctrl_gpio_set_config(chip, offset, config);
+}
+
+static int pin_control_gpio_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct pin_control_gpio_priv *priv;
+	struct gpio_chip *chip;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	chip = &priv->chip;
+	chip->label = dev_name(dev);
+	chip->parent = dev;
+	chip->base = -1;
+
+	chip->request = gpiochip_generic_request;
+	chip->free = gpiochip_generic_free;
+	chip->get_direction = pin_control_gpio_get_direction;
+	chip->direction_input = pinctrl_gpio_direction_input;
+	chip->direction_output = pin_control_gpio_direction_output;
+	chip->get = pin_control_gpio_get;
+	chip->set = pin_control_gpio_set;
+	chip->set_config = gpiochip_generic_config;
+
+	ret = devm_gpiochip_add_data(dev, chip, priv);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, priv);
+
+	return 0;
+}
+
+static const struct of_device_id pin_control_gpio_match[] = {
+	{ .compatible = "scmi-pinctrl-gpio" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, pin_control_gpio_match);
+
+static struct platform_driver pin_control_gpio_driver = {
+	.probe = pin_control_gpio_probe,
+	.driver = {
+		.name = "pin-control-gpio",
+		.of_match_table = pin_control_gpio_match,
+	},
+};
+module_platform_driver(pin_control_gpio_driver);
+
+MODULE_AUTHOR("AKASHI Takahiro <takahiro.akashi@linaro.org>");
+MODULE_DESCRIPTION("Pinctrl based GPIO driver");
+MODULE_LICENSE("GPL");
-- 
2.51.0

Re: [PATCH v4 7/7] gpio: add pinctrl based generic gpio driver

[Andy Shevchenko]

On Tue, Mar 17, 2026 at 05:41:02PM +0300, Dan Carpenter wrote:

> The ARM SCMI pinctrl protocol allows GPIO access.  Instead of creating
> a new SCMI gpio driver, this driver is a generic GPIO driver that uses

GPIO

> standard pinctrl interfaces.

...

> +config GPIO_BY_PINCTRL
> +	tristate "GPIO support based on a pure pin control backend"
> +	depends on GPIOLIB
> +	help
> +	  Select this option to support GPIO devices based solely on pin
> +	  control.  This is used to do GPIO over the ARM SCMI protocol.

This is not enough to understand (as discussion in previous round showed).
Can we have added a Documentation/driver-api/gpio/... (to the existing one
or a new one)?

...

> +// Copyright (C) 2023 Linaro Inc.

2026 (as well)?

...

+ errno.h // -ENOMEM, et cetera

> +#include <linux/gpio/driver.h>

> +#include <linux/list.h>

?! Cargo cult?

+ mod_devicetable.h // of_device_id

> +#include <linux/module.h>
> +#include <linux/pinctrl/consumer.h>
> +#include <linux/platform_device.h>
> +#include <linux/types.h>

+ blank line.

> +#include "gpiolib.h"

...

> +struct pin_control_gpio_priv {
> +	struct gpio_chip chip;
> +};

Unneeded, you can use struct gpio_chip directly. No?

...

> +static int pin_control_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
> +{
> +	unsigned long config;
> +	bool in, out;
> +	int ret;
> +
> +	config = PIN_CONFIG_INPUT_ENABLE;
> +	ret = pinctrl_gpio_get_config(gc, offset, &config);
> +	if (ret)
> +		return ret;
> +	in = config;
> +
> +	config = PIN_CONFIG_OUTPUT_ENABLE;
> +	ret = pinctrl_gpio_get_config(gc, offset, &config);
> +	if (ret)
> +		return ret;
> +	out = config;

> +	/* Consistency check - in theory both can be enabled! */
> +	if (in && !out)
> +		return GPIO_LINE_DIRECTION_IN;
> +	if (!in && out)
> +		return GPIO_LINE_DIRECTION_OUT;
> +
> +	return -EINVAL;

When both are enabled it's out direction, so the entire piece
can be simplified to

	if (out)
		return GPIO_LINE_DIRECTION_OUT;

	if (in)
		return GPIO_LINE_DIRECTION_IN;

	return ...something...; ideally it should be HiZ.

So, even more simplified will be just

	if (out)
		return GPIO_LINE_DIRECTION_OUT;
	else
		return GPIO_LINE_DIRECTION_IN;

> +}

...

> +	ret = devm_gpiochip_add_data(dev, chip, priv);
> +	if (ret)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, priv);

Not used.

> +	return 0;

Hence, the entire piece is just

	return devm_gpiochip_add_data(dev, chip, priv);

-- 
With Best Regards,
Andy Shevchenko