[RFC PATCH v2 0/2] Multicolor PWM LED support

[RFC PATCH v2 0/2] Multicolor PWM LED support

[sven]

From: Sven Schwermer <sven.schwermer@disruptive-technologies.com>

Hi,

As previously discussed [1] on the linux-leds list I am missing
multicolor PWM LED support. In the mean time I have put together a
working prototype for such a driver. This is my first Linux driver
so I'm hoping for some feedback. Here are some questions that came up
while putting this thing together:

  1. Currently, the max-brightness property is expected as a property to
     the multi-led node. That seems consistent with the existing
     multicolor class code, but I'm wondering whether it would make
     sense to have a max-brigthness for the individual LEDs as well?
  2. The current multi-led node definition calls for a node index which
     would in turn require the reg property to be set within the node.
     In this context, that doesn't seem to make sense. Should this
     requirement be lifted from leds-class-multicolor.yaml?
  3. I'm not currently reusing any leds-pwm code because there aren't
     too many overlaps. Does anyone have suggestions what could be
     factored out into a common source file?

I would appreciate if anyone would test this code. It runs on my
i.MX6ULL-based hardware.

Best regards,
Sven

[1]: https://www.spinics.net/lists/linux-leds/msg19988.html

Sven Schwermer (2):
  dt-bindings: leds: Add multicolor PWM LED bindings
  leds: Add PWM multicolor driver

 .../bindings/leds/leds-pwm-multicolor.yaml    |  76 ++++++++
 drivers/leds/Kconfig                          |   8 +
 drivers/leds/Makefile                         |   1 +
 drivers/leds/leds-pwm-multicolor.c            | 184 ++++++++++++++++++
 4 files changed, 269 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml
 create mode 100644 drivers/leds/leds-pwm-multicolor.c

Interdiff against v1:
diff --git a/Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml b/Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml
index 8552a5498bdd..b82b26f2e140 100644
--- a/Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml
+++ b/Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml
@@ -14,7 +14,8 @@ description: |
   LED using the multicolor LED class.
 
 properties:
-  compatible: pwm-leds-multicolor
+  compatible:
+    const: pwm-leds-multicolor
 
 patternProperties:
   '^multi-led@[0-9a-f]$':
@@ -34,10 +35,12 @@ patternProperties:
           color:
             $ref: common.yaml#/properties/color
 
+        required:
+          - pwms
+          - color
+
 required:
   - compatible
-  - pwms
-  - color
 
 additionalProperties: false
 
-- 
2.35.0

[RFC PATCH v2 1/2] dt-bindings: leds: Add multicolor PWM LED bindings

[sven]

From: Sven Schwermer <sven.schwermer@disruptive-technologies.com>

This allows to group multiple PWM-connected monochrome LEDs into
multicolor LEDs, e.g. RGB LEDs.

Signed-off-by: Sven Schwermer <sven.schwermer@disruptive-technologies.com>
---
 .../bindings/leds/leds-pwm-multicolor.yaml    | 76 +++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml

diff --git a/Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml b/Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml
new file mode 100644
index 000000000000..b82b26f2e140
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml
@@ -0,0 +1,76 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/leds-pwm-multicolor.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Multi-color LEDs connected to PWM
+
+maintainers:
+  - Sven Schwermer <sven.schwermer@disruptive-technologies.com>
+
+description: |
+  This driver combines several monochrome PWM LEDs into one multi-color
+  LED using the multicolor LED class.
+
+properties:
+  compatible:
+    const: pwm-leds-multicolor
+
+patternProperties:
+  '^multi-led@[0-9a-f]$':
+    type: object
+    allOf:
+      - $ref: leds-class-multicolor.yaml#
+
+    patternProperties:
+      "^led-[0-9a-z]+$":
+        type: object
+        properties:
+          pwms:
+            maxItems: 1
+
+          pwm-names: true
+
+          color:
+            $ref: common.yaml#/properties/color
+
+        required:
+          - pwms
+          - color
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/leds/common.h>
+
+    rgb-led {
+        compatible = "pwm-leds-multicolor";
+
+        multi-led@0 {
+          color = <LED_COLOR_ID_RGB>;
+          function = LED_FUNCTION_INDICATOR;
+          max-brightness = <65535>;
+
+          led-red {
+              pwms = <&pwm1 0 1000000>;
+              color = <LED_COLOR_ID_RED>;
+          };
+
+          led-green {
+              pwms = <&pwm2 0 1000000>;
+              color = <LED_COLOR_ID_GREEN>;
+          };
+
+          led-blue {
+              pwms = <&pwm3 0 1000000>;
+              color = <LED_COLOR_ID_BLUE>;
+          };
+        };
+    };
+
+...
-- 
2.35.0

Re: [RFC PATCH v2 1/2] dt-bindings: leds: Add multicolor PWM LED bindings

[Marek Behún]

On Tue, 25 Jan 2022 16:12:25 +0100
sven@svenschwermer.de wrote:

> From: Sven Schwermer <sven.schwermer@disruptive-technologies.com>
> 
> This allows to group multiple PWM-connected monochrome LEDs into
> multicolor LEDs, e.g. RGB LEDs.
> 
> Signed-off-by: Sven Schwermer <sven.schwermer@disruptive-technologies.com>
> ---
>  .../bindings/leds/leds-pwm-multicolor.yaml    | 76 +++++++++++++++++++
>  1 file changed, 76 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml
> 
> diff --git a/Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml b/Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml
> new file mode 100644
> index 000000000000..b82b26f2e140
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml
> @@ -0,0 +1,76 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/leds-pwm-multicolor.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Multi-color LEDs connected to PWM
> +
> +maintainers:
> +  - Sven Schwermer <sven.schwermer@disruptive-technologies.com>
> +
> +description: |
> +  This driver combines several monochrome PWM LEDs into one multi-color
> +  LED using the multicolor LED class.
> +
> +properties:
> +  compatible:
> +    const: pwm-leds-multicolor
> +
> +patternProperties:
> +  '^multi-led@[0-9a-f]$':
> +    type: object
> +    allOf:
> +      - $ref: leds-class-multicolor.yaml#
> +
> +    patternProperties:
> +      "^led-[0-9a-z]+$":
> +        type: object
> +        properties:
> +          pwms:
> +            maxItems: 1
> +
> +          pwm-names: true
> +
> +          color:
> +            $ref: common.yaml#/properties/color
> +
> +        required:
> +          - pwms
> +          - color
> +
> +required:
> +  - compatible
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/leds/common.h>
> +
> +    rgb-led {
> +        compatible = "pwm-leds-multicolor";
> +
> +        multi-led@0 {
> +          color = <LED_COLOR_ID_RGB>;
> +          function = LED_FUNCTION_INDICATOR;
> +          max-brightness = <65535>;
> +
> +          led-red {
> +              pwms = <&pwm1 0 1000000>;
> +              color = <LED_COLOR_ID_RED>;
> +          };
> +
> +          led-green {
> +              pwms = <&pwm2 0 1000000>;
> +              color = <LED_COLOR_ID_GREEN>;
> +          };
> +
> +          led-blue {
> +              pwms = <&pwm3 0 1000000>;
> +              color = <LED_COLOR_ID_BLUE>;
> +          };
> +        };

what about

	multi-led@0 {
		color = <LED_COLOR_ID_RGB>;
		function = LED_FUNCTION_INDICATOR;
		pwms = <&pwm1 0 1000000>,
		       <&pwm2 0 1000000>,
		       <&pwm3 0 1000000>;
		channels = <LED_COLOR_ID_RED>,
			   <LED_COLOR_ID_GREEN>,
			   <LED_COLOR_ID_BLUE>;
	};

I am not saying that it is necessarily better, just comenting that
maybe it is, since it saves some space. `pwms` is phandle-array, so it
can contain references to multiple pwms, and we have functions which
make getting these pwms in driver code easy...

Also this example won't compile with
   make dt_bindings_check
because you don't have pwm1, pwm2
and pwm3 defined...

Marek

Re: [RFC PATCH v2 1/2] dt-bindings: leds: Add multicolor PWM LED bindings

[Sven Schwermer]

Hi Marek,

On 1/25/22 21:27, Marek Behún wrote:

> what about
> 
> 	multi-led@0 {
> 		color = <LED_COLOR_ID_RGB>;
> 		function = LED_FUNCTION_INDICATOR;
> 		pwms = <&pwm1 0 1000000>,
> 		       <&pwm2 0 1000000>,
> 		       <&pwm3 0 1000000>;
> 		channels = <LED_COLOR_ID_RED>,
> 			   <LED_COLOR_ID_GREEN>,
> 			   <LED_COLOR_ID_BLUE>;
> 	};
> 
> I am not saying that it is necessarily better, just comenting that
> maybe it is, since it saves some space. `pwms` is phandle-array, so it
> can contain references to multiple pwms, and we have functions which
> make getting these pwms in driver code easy...

This this nice. I misunderstood the requirements by the multicolor LED 
class so I didn't think this was possible. I will change my patch.

> Also this example won't compile with
>     make dt_bindings_check
> because you don't have pwm1, pwm2
> and pwm3 defined...

Yes, it does. The checker compiles the example DTS snippets with this in 
the header: /plugin/; // silence any missing phandle references

Best regards,
Sven

Re: [RFC PATCH v2 1/2] dt-bindings: leds: Add multicolor PWM LED bindings

[Sven Schwermer]

On 1/25/22 21:27, Marek Behún wrote:

> what about
> 
> 	multi-led@0 {
> 		color = <LED_COLOR_ID_RGB>;
> 		function = LED_FUNCTION_INDICATOR;
> 		pwms = <&pwm1 0 1000000>,
> 		       <&pwm2 0 1000000>,
> 		       <&pwm3 0 1000000>;
> 		channels = <LED_COLOR_ID_RED>,
> 			   <LED_COLOR_ID_GREEN>,
> 			   <LED_COLOR_ID_BLUE>;
> 	};
> 
> I am not saying that it is necessarily better, just comenting that
> maybe it is, since it saves some space. `pwms` is phandle-array, so it
> can contain references to multiple pwms, and we have functions which
> make getting these pwms in driver code easy...

I have had another look at this. It seems like if you specify more than 
one PWM instance in the `pwms` property, the device tree must specify 
`pwm-names` in order for the driver to be able to request the correct 
instance (see `of_pwm_get`). In this case, the device tree would need to 
contain some strings in `pwm-names` that allow the driver to match them 
against the color IDs. Alternatively, I could re-implement the PWM 
instance request logic. Both options seem not ideal.

For the next version of this patch series, I'll go with my original 
approach. I'm open for alternatives :)

Best regards,
Sven

Re: [RFC PATCH v2 1/2] dt-bindings: leds: Add multicolor PWM LED bindings

[Rob Herring]

On Tue, 25 Jan 2022 16:12:25 +0100, sven@svenschwermer.de wrote:
> From: Sven Schwermer <sven.schwermer@disruptive-technologies.com>
> 
> This allows to group multiple PWM-connected monochrome LEDs into
> multicolor LEDs, e.g. RGB LEDs.
> 
> Signed-off-by: Sven Schwermer <sven.schwermer@disruptive-technologies.com>
> ---
>  .../bindings/leds/leds-pwm-multicolor.yaml    | 76 +++++++++++++++++++
>  1 file changed, 76 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml
> 

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:
Documentation/devicetree/bindings/leds/leds-pwm-multicolor.example.dts:24.25-43.15: Warning (unit_address_vs_reg): /example-0/rgb-led/multi-led@0: node has a unit name, but no reg or ranges property

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/patch/1584106

This check can fail if there are any dependencies. The base for a patch
series is generally the most recent rc1.

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.

[RFC PATCH v2 2/2] leds: Add PWM multicolor driver

[sven]

From: Sven Schwermer <sven.schwermer@disruptive-technologies.com>

By allowing to group multiple monochrome PWM LEDs into multicolor LEDs,
all involved LEDs can be controlled in-sync. This enables using effects
using triggers, etc.

Signed-off-by: Sven Schwermer <sven.schwermer@disruptive-technologies.com>
---
 drivers/leds/Kconfig               |   8 ++
 drivers/leds/Makefile              |   1 +
 drivers/leds/leds-pwm-multicolor.c | 184 +++++++++++++++++++++++++++++
 3 files changed, 193 insertions(+)
 create mode 100644 drivers/leds/leds-pwm-multicolor.c

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 6090e647daee..bae1f63f6195 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -552,6 +552,14 @@ config LEDS_PWM
 	help
 	  This option enables support for pwm driven LEDs
 
+config LEDS_PWM_MULTICOLOR
+	tristate "PWM driven multi-color LED Support"
+	depends on LEDS_CLASS_MULTICOLOR
+	depends on PWM
+	help
+	  This option enables support for PWM driven monochrome LEDs that are
+	  grouped into multicolor LEDs.
+
 config LEDS_REGULATOR
 	tristate "REGULATOR driven LED support"
 	depends on LEDS_CLASS
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index e58ecb36360f..ba2c2c1edf12 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -73,6 +73,7 @@ obj-$(CONFIG_LEDS_PCA963X)		+= leds-pca963x.o
 obj-$(CONFIG_LEDS_PM8058)		+= leds-pm8058.o
 obj-$(CONFIG_LEDS_POWERNV)		+= leds-powernv.o
 obj-$(CONFIG_LEDS_PWM)			+= leds-pwm.o
+obj-$(CONFIG_LEDS_PWM_MULTICOLOR)	+= leds-pwm-multicolor.o
 obj-$(CONFIG_LEDS_REGULATOR)		+= leds-regulator.o
 obj-$(CONFIG_LEDS_S3C24XX)		+= leds-s3c24xx.o
 obj-$(CONFIG_LEDS_SC27XX_BLTC)		+= leds-sc27xx-bltc.o
diff --git a/drivers/leds/leds-pwm-multicolor.c b/drivers/leds/leds-pwm-multicolor.c
new file mode 100644
index 000000000000..c54bed4536d3
--- /dev/null
+++ b/drivers/leds/leds-pwm-multicolor.c
@@ -0,0 +1,184 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * PWM-based multi-color LED control
+ *
+ * Copyright 2022 Sven Schwermer <sven.schwermer@disruptive-technologies.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/led-class-multicolor.h>
+#include <linux/leds.h>
+#include <linux/err.h>
+#include <linux/pwm.h>
+#include <linux/mutex.h>
+
+struct pwm_led {
+	struct pwm_device *pwm;
+	struct pwm_state pwmstate;
+};
+
+struct pwm_mc_led {
+	struct led_classdev_mc mc_cdev;
+	struct mutex lock;
+	struct pwm_led leds[];
+};
+
+static int led_pwm_mc_set(struct led_classdev *cdev,
+			  enum led_brightness brightness)
+{
+	int i;
+	unsigned long long duty;
+	int ret = 0;
+	struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
+	struct pwm_mc_led *priv = container_of(mc_cdev, struct pwm_mc_led, mc_cdev);
+
+	led_mc_calc_color_components(mc_cdev, brightness);
+
+	mutex_lock(&priv->lock);
+
+	for (i = 0; i < mc_cdev->num_colors; ++i) {
+		duty = priv->leds[i].pwmstate.period;
+		duty *= mc_cdev->subled_info[i].brightness;
+		do_div(duty, cdev->max_brightness);
+
+		priv->leds[i].pwmstate.duty_cycle = duty;
+		priv->leds[i].pwmstate.enabled = duty > 0;
+		ret = pwm_apply_state(priv->leds[i].pwm,
+				      &priv->leds[i].pwmstate);
+		if (ret)
+			break;
+	}
+
+	mutex_unlock(&priv->lock);
+
+	return ret;
+}
+
+static int led_pwm_mc_probe(struct platform_device *pdev)
+{
+	struct fwnode_handle *mcnode, *fwnode;
+	int count = 0;
+	struct pwm_mc_led *priv;
+	struct mc_subled *subled;
+	struct led_classdev *cdev;
+	struct pwm_led *pwmled;
+	u32 color;
+	int ret = 0;
+	struct led_init_data init_data = {};
+
+	mcnode = device_get_named_child_node(&pdev->dev, "multi-led");
+	if (!mcnode) {
+		dev_err(&pdev->dev, "expected multi-led node\n");
+		ret = -ENODEV;
+		goto out;
+	}
+
+	/* count the nodes inside the multi-led node */
+	fwnode_for_each_child_node(mcnode, fwnode)
+		++count;
+
+	priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
+			    GFP_KERNEL);
+	if (!priv) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	mutex_init(&priv->lock);
+
+	subled = devm_kcalloc(&pdev->dev, count, sizeof(*subled), GFP_KERNEL);
+	if (!subled) {
+		ret = -ENOMEM;
+		goto destroy_mutex;
+	}
+	priv->mc_cdev.subled_info = subled;
+
+	/* init the multicolor's LED class device */
+	cdev = &priv->mc_cdev.led_cdev;
+	fwnode_property_read_string(mcnode, "label", &cdev->name);
+	cdev->brightness = LED_OFF;
+	fwnode_property_read_u32(mcnode, "max-brightness",
+				 &cdev->max_brightness);
+	cdev->flags = LED_CORE_SUSPENDRESUME;
+	cdev->brightness_set_blocking = led_pwm_mc_set;
+
+	/* iterate over the nodes inside the multi-led node */
+	fwnode_for_each_child_node(mcnode, fwnode) {
+		pwmled = &priv->leds[priv->mc_cdev.num_colors];
+		pwmled->pwm = devm_fwnode_pwm_get(&pdev->dev, fwnode, NULL);
+		if (IS_ERR(pwmled->pwm)) {
+			ret = PTR_ERR(pwmled->pwm);
+			dev_err(&pdev->dev, "unable to request PWM: %d\n", ret);
+			goto destroy_mutex;
+		}
+		pwm_init_state(pwmled->pwm, &pwmled->pwmstate);
+
+		ret = fwnode_property_read_u32(fwnode, "color", &color);
+		if (ret) {
+			dev_err(&pdev->dev, "cannot read color: %d\n", ret);
+			goto destroy_mutex;
+		}
+
+		subled[priv->mc_cdev.num_colors].color_index = color;
+		subled[priv->mc_cdev.num_colors].channel =
+			priv->mc_cdev.num_colors;
+		++priv->mc_cdev.num_colors;
+	}
+
+	init_data.fwnode = mcnode;
+	ret = devm_led_classdev_multicolor_register_ext(&pdev->dev,
+							&priv->mc_cdev,
+							&init_data);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"failed to register multicolor PWM led for %s: %d\n",
+			cdev->name, ret);
+		goto destroy_mutex;
+	}
+
+	ret = led_pwm_mc_set(cdev, cdev->brightness);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to set led PWM value for %s: %d",
+			cdev->name, ret);
+		goto destroy_mutex;
+	}
+
+	platform_set_drvdata(pdev, priv);
+	return 0;
+
+destroy_mutex:
+	mutex_destroy(&priv->lock);
+out:
+	return ret;
+}
+
+static int led_pwm_mc_remove(struct platform_device *pdev)
+{
+	struct pwm_mc_led *priv = platform_get_drvdata(pdev);
+
+	mutex_destroy(&priv->lock);
+	return 0;
+}
+
+static const struct of_device_id of_pwm_leds_mc_match[] = {
+	{ .compatible = "pwm-leds-multicolor", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_pwm_leds_mc_match);
+
+static struct platform_driver led_pwm_mc_driver = {
+	.probe		= led_pwm_mc_probe,
+	.remove		= led_pwm_mc_remove,
+	.driver		= {
+		.name	= "leds_pwm_multicolor",
+		.of_match_table = of_pwm_leds_mc_match,
+	},
+};
+
+module_platform_driver(led_pwm_mc_driver);
+
+MODULE_AUTHOR("Sven Schwermer <sven.schwermer@disruptive-technologies.com>");
+MODULE_DESCRIPTION("multi-color PWM LED driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:leds-pwm-multicolor");
-- 
2.35.0

Re: [RFC PATCH v2 2/2] leds: Add PWM multicolor driver

[Marek Behún]

On Tue, 25 Jan 2022 16:12:26 +0100
sven@svenschwermer.de wrote:

> From: Sven Schwermer <sven.schwermer@disruptive-technologies.com>
> 
> By allowing to group multiple monochrome PWM LEDs into multicolor LEDs,
> all involved LEDs can be controlled in-sync. This enables using effects
> using triggers, etc.
> 
> Signed-off-by: Sven Schwermer <sven.schwermer@disruptive-technologies.com>
> ---
>  drivers/leds/Kconfig               |   8 ++
>  drivers/leds/Makefile              |   1 +
>  drivers/leds/leds-pwm-multicolor.c | 184 +++++++++++++++++++++++++++++
>  3 files changed, 193 insertions(+)
>  create mode 100644 drivers/leds/leds-pwm-multicolor.c
> 
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 6090e647daee..bae1f63f6195 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -552,6 +552,14 @@ config LEDS_PWM
>  	help
>  	  This option enables support for pwm driven LEDs
>  
> +config LEDS_PWM_MULTICOLOR
> +	tristate "PWM driven multi-color LED Support"
> +	depends on LEDS_CLASS_MULTICOLOR
> +	depends on PWM
> +	help
> +	  This option enables support for PWM driven monochrome LEDs that are
> +	  grouped into multicolor LEDs.
> +
>  config LEDS_REGULATOR
>  	tristate "REGULATOR driven LED support"
>  	depends on LEDS_CLASS
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index e58ecb36360f..ba2c2c1edf12 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -73,6 +73,7 @@ obj-$(CONFIG_LEDS_PCA963X)		+= leds-pca963x.o
>  obj-$(CONFIG_LEDS_PM8058)		+= leds-pm8058.o
>  obj-$(CONFIG_LEDS_POWERNV)		+= leds-powernv.o
>  obj-$(CONFIG_LEDS_PWM)			+= leds-pwm.o
> +obj-$(CONFIG_LEDS_PWM_MULTICOLOR)	+= leds-pwm-multicolor.o
>  obj-$(CONFIG_LEDS_REGULATOR)		+= leds-regulator.o
>  obj-$(CONFIG_LEDS_S3C24XX)		+= leds-s3c24xx.o
>  obj-$(CONFIG_LEDS_SC27XX_BLTC)		+= leds-sc27xx-bltc.o
> diff --git a/drivers/leds/leds-pwm-multicolor.c b/drivers/leds/leds-pwm-multicolor.c
> new file mode 100644
> index 000000000000..c54bed4536d3
> --- /dev/null
> +++ b/drivers/leds/leds-pwm-multicolor.c
> @@ -0,0 +1,184 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * PWM-based multi-color LED control
> + *
> + * Copyright 2022 Sven Schwermer <sven.schwermer@disruptive-technologies.com>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/platform_device.h>
> +#include <linux/led-class-multicolor.h>
> +#include <linux/leds.h>
> +#include <linux/err.h>
> +#include <linux/pwm.h>
> +#include <linux/mutex.h>

sort headers alphabetically

> +
> +struct pwm_led {
> +	struct pwm_device *pwm;
> +	struct pwm_state pwmstate;

maybe rename pwmstate to just state?

> +};
> +
> +struct pwm_mc_led {
> +	struct led_classdev_mc mc_cdev;
> +	struct mutex lock;
> +	struct pwm_led leds[];
> +};
> +
> +static int led_pwm_mc_set(struct led_classdev *cdev,
> +			  enum led_brightness brightness)
> +{
> +	int i;
> +	unsigned long long duty;
> +	int ret = 0;
> +	struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
> +	struct pwm_mc_led *priv = container_of(mc_cdev, struct pwm_mc_led, mc_cdev);
> +
> +	led_mc_calc_color_components(mc_cdev, brightness);
> +
> +	mutex_lock(&priv->lock);
> +
> +	for (i = 0; i < mc_cdev->num_colors; ++i) {
> +		duty = priv->leds[i].pwmstate.period;
> +		duty *= mc_cdev->subled_info[i].brightness;
> +		do_div(duty, cdev->max_brightness);
> +
> +		priv->leds[i].pwmstate.duty_cycle = duty;
> +		priv->leds[i].pwmstate.enabled = duty > 0;
> +		ret = pwm_apply_state(priv->leds[i].pwm,
> +				      &priv->leds[i].pwmstate);
> +		if (ret)
> +			break;
> +	}
> +
> +	mutex_unlock(&priv->lock);
> +
> +	return ret;
> +}
> +
> +static int led_pwm_mc_probe(struct platform_device *pdev)
> +{
> +	struct fwnode_handle *mcnode, *fwnode;
> +	int count = 0;
> +	struct pwm_mc_led *priv;
> +	struct mc_subled *subled;
> +	struct led_classdev *cdev;
> +	struct pwm_led *pwmled;
> +	u32 color;
> +	int ret = 0;
> +	struct led_init_data init_data = {};
> +
> +	mcnode = device_get_named_child_node(&pdev->dev, "multi-led");
> +	if (!mcnode) {
> +		dev_err(&pdev->dev, "expected multi-led node\n");
> +		ret = -ENODEV;
> +		goto out;
> +	}
> +
> +	/* count the nodes inside the multi-led node */
> +	fwnode_for_each_child_node(mcnode, fwnode)
> +		++count;
> +
> +	priv = devm_kzalloc(&pdev->dev, struct_size(priv, leds, count),
> +			    GFP_KERNEL);
> +	if (!priv) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +	mutex_init(&priv->lock);
> +
> +	subled = devm_kcalloc(&pdev->dev, count, sizeof(*subled), GFP_KERNEL);
> +	if (!subled) {
> +		ret = -ENOMEM;
> +		goto destroy_mutex;
> +	}
> +	priv->mc_cdev.subled_info = subled;
> +
> +	/* init the multicolor's LED class device */
> +	cdev = &priv->mc_cdev.led_cdev;
> +	fwnode_property_read_string(mcnode, "label", &cdev->name);

	label is deprecated, do not introduce in new bindings

> +	cdev->brightness = LED_OFF;

dont use this LED_OFF/LED_ON constants, they are deprecated

> +	fwnode_property_read_u32(mcnode, "max-brightness",
> +				 &cdev->max_brightness);
> +	cdev->flags = LED_CORE_SUSPENDRESUME;
> +	cdev->brightness_set_blocking = led_pwm_mc_set;
> +
> +	/* iterate over the nodes inside the multi-led node */
> +	fwnode_for_each_child_node(mcnode, fwnode) {
> +		pwmled = &priv->leds[priv->mc_cdev.num_colors];
> +		pwmled->pwm = devm_fwnode_pwm_get(&pdev->dev, fwnode, NULL);
> +		if (IS_ERR(pwmled->pwm)) {
> +			ret = PTR_ERR(pwmled->pwm);
> +			dev_err(&pdev->dev, "unable to request PWM: %d\n", ret);

you need to release the fwnode with fwnode_handle_put(fwnode) here

> +			goto destroy_mutex;
> +		}
> +		pwm_init_state(pwmled->pwm, &pwmled->pwmstate);
> +
> +		ret = fwnode_property_read_u32(fwnode, "color", &color);
> +		if (ret) {
> +			dev_err(&pdev->dev, "cannot read color: %d\n", ret);

you need to release the fwnode with fwnode_handle_put(fwnode) here

> +			goto destroy_mutex;
> +		}
> +
> +		subled[priv->mc_cdev.num_colors].color_index = color;
> +		subled[priv->mc_cdev.num_colors].channel =
> +			priv->mc_cdev.num_colors;
> +		++priv->mc_cdev.num_colors;
> +	}
> +
> +	init_data.fwnode = mcnode;
> +	ret = devm_led_classdev_multicolor_register_ext(&pdev->dev,
> +							&priv->mc_cdev,
> +							&init_data);
> +	if (ret) {
> +		dev_err(&pdev->dev,
> +			"failed to register multicolor PWM led for %s: %d\n",
> +			cdev->name, ret);
> +		goto destroy_mutex;
> +	}
> +
> +	ret = led_pwm_mc_set(cdev, cdev->brightness);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to set led PWM value for %s: %d",
> +			cdev->name, ret);
> +		goto destroy_mutex;
> +	}
> +

you need to release mcnode with fwnode_handle_put(). You increased reference
count with device_get_named_child_node()

> +	platform_set_drvdata(pdev, priv);
> +	return 0;
> +
> +destroy_mutex:
> +	mutex_destroy(&priv->lock);
> +out:

here as well you need to release mcnode with fwnode_handle_put()

> +	return ret;
> +}
> +
> +static int led_pwm_mc_remove(struct platform_device *pdev)
> +{
> +	struct pwm_mc_led *priv = platform_get_drvdata(pdev);
> +
> +	mutex_destroy(&priv->lock);
> +	return 0;
> +}
> +
> +static const struct of_device_id of_pwm_leds_mc_match[] = {
> +	{ .compatible = "pwm-leds-multicolor", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, of_pwm_leds_mc_match);
> +
> +static struct platform_driver led_pwm_mc_driver = {
> +	.probe		= led_pwm_mc_probe,
> +	.remove		= led_pwm_mc_remove,
> +	.driver		= {
> +		.name	= "leds_pwm_multicolor",
> +		.of_match_table = of_pwm_leds_mc_match,
> +	},
> +};
> +
> +module_platform_driver(led_pwm_mc_driver);
> +
> +MODULE_AUTHOR("Sven Schwermer <sven.schwermer@disruptive-technologies.com>");
> +MODULE_DESCRIPTION("multi-color PWM LED driver");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:leds-pwm-multicolor");