[PATCH v3 0/4] Add a multicolor LED driver for groups of monochromatic LEDs

[PATCH v3 0/4] Add a multicolor LED driver for groups of monochromatic LEDs

[Jean-Jacques Hiblot]

Some HW design implement multicolor LEDs with several monochromatic LEDs.
Grouping the monochromatic LEDs allows to configure them in sync and use
the triggers.
The PWM multicolor LED driver implements such grouping but only for
PWM-based LEDs. As this feature is also desirable for the other types of
LEDs, this series implements it for any kind of LED device.

changes v2->v3, only minor changes:
 - rephrased the Kconfig descritpion
 - make the sysfs interface of underlying LEDs read-only only if the probe
   is successful.
 - sanitize the header files
 - removed the useless call to dev_set_drvdata()
 - use dev_fwnode() to get the fwnode to the device.

Jean-Jacques Hiblot (4):
  leds: class: simplify the implementation of devm_of_led_get()
  leds: class: store the color index in struct led_classdev
  dt-bindings: leds: Add binding for a multicolor group of LEDs
  leds: Add a multicolor LED driver to group monochromatic LEDs

 .../bindings/leds/leds-group-multicolor.yaml  |  61 +++++++
 drivers/leds/led-class.c                      |  27 ++--
 drivers/leds/rgb/Kconfig                      |   6 +
 drivers/leds/rgb/Makefile                     |   1 +
 drivers/leds/rgb/leds-group-multicolor.c      | 153 ++++++++++++++++++
 include/linux/leds.h                          |   1 +
 6 files changed, 235 insertions(+), 14 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-group-multicolor.yaml
 create mode 100644 drivers/leds/rgb/leds-group-multicolor.c

-- 
2.25.1

[PATCH v3 1/4] leds: class: simplify the implementation of devm_of_led_get()

[Jean-Jacques Hiblot]

Use the devm_add_action_or_reset() helper.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
---
 drivers/leds/led-class.c | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 6a8ea94834fa..2c0d979d0c8a 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -258,11 +258,9 @@ void led_put(struct led_classdev *led_cdev)
 }
 EXPORT_SYMBOL_GPL(led_put);
 
-static void devm_led_release(struct device *dev, void *res)
+static void devm_led_release(void *cdev)
 {
-	struct led_classdev **p = res;
-
-	led_put(*p);
+	led_put(cdev);
 }
 
 /**
@@ -280,7 +278,7 @@ struct led_classdev *__must_check devm_of_led_get(struct device *dev,
 						  int index)
 {
 	struct led_classdev *led;
-	struct led_classdev **dr;
+	int ret;
 
 	if (!dev)
 		return ERR_PTR(-EINVAL);
@@ -289,15 +287,9 @@ struct led_classdev *__must_check devm_of_led_get(struct device *dev,
 	if (IS_ERR(led))
 		return led;
 
-	dr = devres_alloc(devm_led_release, sizeof(struct led_classdev *),
-			  GFP_KERNEL);
-	if (!dr) {
-		led_put(led);
-		return ERR_PTR(-ENOMEM);
-	}
-
-	*dr = led;
-	devres_add(dev, dr);
+	ret = devm_add_action_or_reset(dev, devm_led_release, led);
+	if (ret)
+		return ERR_PTR(ret);
 
 	return led;
 }
-- 
2.25.1

[PATCH v3 2/4] leds: class: store the color index in struct led_classdev

[Jean-Jacques Hiblot]

This information might be useful for more than only deriving the led's
name.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
---
 drivers/leds/led-class.c | 7 +++++++
 include/linux/leds.h     | 1 +
 2 files changed, 8 insertions(+)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 2c0d979d0c8a..537379f09801 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -350,6 +350,10 @@ int led_classdev_register_ext(struct device *parent,
 			if (fwnode_property_present(init_data->fwnode,
 						    "retain-state-shutdown"))
 				led_cdev->flags |= LED_RETAIN_AT_SHUTDOWN;
+
+			if (fwnode_property_present(init_data->fwnode, "color"))
+				fwnode_property_read_u32(init_data->fwnode, "color",
+							 &led_cdev->color);
 		}
 	} else {
 		proposed_name = led_cdev->name;
@@ -359,6 +363,9 @@ int led_classdev_register_ext(struct device *parent,
 	if (ret < 0)
 		return ret;
 
+	if (led_cdev->color >= LED_COLOR_ID_MAX)
+		dev_warn(parent, "LED %s color identifier out of range\n", final_name);
+
 	mutex_init(&led_cdev->led_access);
 	mutex_lock(&led_cdev->led_access);
 	led_cdev->dev = device_create_with_groups(leds_class, parent, 0,
diff --git a/include/linux/leds.h b/include/linux/leds.h
index ba4861ec73d3..fe6346604e36 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -71,6 +71,7 @@ struct led_classdev {
 	const char		*name;
 	unsigned int brightness;
 	unsigned int max_brightness;
+	unsigned int color;
 	int			 flags;
 
 	/* Lower 16 bits reflect status */
-- 
2.25.1

[PATCH v3 3/4] dt-bindings: leds: Add binding for a multicolor group of LEDs

[Jean-Jacques Hiblot]

This allows to group multiple monochromatic LEDs into a multicolor
LED, e.g. RGB LEDs.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../bindings/leds/leds-group-multicolor.yaml  | 61 +++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-group-multicolor.yaml

diff --git a/Documentation/devicetree/bindings/leds/leds-group-multicolor.yaml b/Documentation/devicetree/bindings/leds/leds-group-multicolor.yaml
new file mode 100644
index 000000000000..79e5882a08e2
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/leds-group-multicolor.yaml
@@ -0,0 +1,61 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/leds-group-multicolor.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Multi-color LED built with monochromatic LEDs
+
+maintainers:
+  - Jean-Jacques Hiblot <jjhiblot@traphandler.com>
+
+description: |
+  This driver combines several monochromatic LEDs into one multi-color
+  LED using the multicolor LED class.
+
+properties:
+  compatible:
+    const: leds-group-multicolor
+
+  leds:
+    description:
+      An aray of monochromatic leds
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+
+required:
+  - leds
+
+allOf:
+  - $ref: leds-class-multicolor.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/leds/common.h>
+
+    monochromatic-leds {
+        compatible = "gpio-leds";
+
+        led0: led-0 {
+            gpios = <&mcu_pio 0 GPIO_ACTIVE_LOW>;
+        };
+
+        led1: led-1 {
+            gpios = <&mcu_pio 1 GPIO_ACTIVE_HIGH>;
+        };
+
+        led2: led-2 {
+            gpios = <&mcu_pio 1 GPIO_ACTIVE_HIGH>;
+        };
+    };
+
+    multi-led {
+        compatible = "leds-group-multicolor";
+        color = <LED_COLOR_ID_RGB>;
+        function = LED_FUNCTION_INDICATOR;
+        leds = <&led0>, <&led1>, <&led2>;
+    };
+
+...
-- 
2.25.1

[PATCH v3 4/4] leds: Add a multicolor LED driver to group monochromatic LEDs

[Jean-Jacques Hiblot]

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

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
---
 drivers/leds/rgb/Kconfig                 |   6 +
 drivers/leds/rgb/Makefile                |   1 +
 drivers/leds/rgb/leds-group-multicolor.c | 153 +++++++++++++++++++++++
 3 files changed, 160 insertions(+)
 create mode 100644 drivers/leds/rgb/leds-group-multicolor.c

diff --git a/drivers/leds/rgb/Kconfig b/drivers/leds/rgb/Kconfig
index 204cf470beae..c2610c47a82d 100644
--- a/drivers/leds/rgb/Kconfig
+++ b/drivers/leds/rgb/Kconfig
@@ -2,6 +2,12 @@
 
 if LEDS_CLASS_MULTICOLOR
 
+config LEDS_GRP_MULTICOLOR
+	tristate "Multi-color LED grouping support"
+	help
+	  This option enables support for monochrome LEDs that are
+	  grouped into multicolor LEDs.
+
 config LEDS_PWM_MULTICOLOR
 	tristate "PWM driven multi-color LED Support"
 	depends on PWM
diff --git a/drivers/leds/rgb/Makefile b/drivers/leds/rgb/Makefile
index 0675bc0f6e18..4de087ad79bc 100644
--- a/drivers/leds/rgb/Makefile
+++ b/drivers/leds/rgb/Makefile
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
 
+obj-$(CONFIG_LEDS_GRP_MULTICOLOR)	+= leds-group-multicolor.o
 obj-$(CONFIG_LEDS_PWM_MULTICOLOR)	+= leds-pwm-multicolor.o
 obj-$(CONFIG_LEDS_QCOM_LPG)		+= leds-qcom-lpg.o
diff --git a/drivers/leds/rgb/leds-group-multicolor.c b/drivers/leds/rgb/leds-group-multicolor.c
new file mode 100644
index 000000000000..61f9e1954fc4
--- /dev/null
+++ b/drivers/leds/rgb/leds-group-multicolor.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * multi-color LED built with monochromatic LED devices
+ *
+ * Copyright 2022 Jean-Jacques Hiblot <jjhiblot@traphandler.com>
+ */
+
+#include <linux/err.h>
+#include <linux/leds.h>
+#include <linux/led-class-multicolor.h>
+#include <linux/math.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+
+struct led_mcg_priv {
+	struct led_classdev_mc mc_cdev;
+	struct led_classdev **monochromatics;
+};
+
+static int led_mcg_set(struct led_classdev *cdev,
+			  enum led_brightness brightness)
+{
+	struct led_classdev_mc *mc_cdev = lcdev_to_mccdev(cdev);
+	struct led_mcg_priv *priv =
+		container_of(mc_cdev, struct led_mcg_priv, mc_cdev);
+	int i;
+
+	led_mc_calc_color_components(mc_cdev, brightness);
+
+	for (i = 0; i < mc_cdev->num_colors; i++) {
+		struct led_classdev *mono = priv->monochromatics[i];
+		int actual_led_brightness;
+
+		/*
+		 * Scale the intensity according the max brightness of the
+		 * monochromatic LED
+		 */
+		actual_led_brightness = DIV_ROUND_CLOSEST(
+			mono->max_brightness * mc_cdev->subled_info[i].brightness,
+			mc_cdev->led_cdev.max_brightness);
+
+		led_set_brightness(mono, actual_led_brightness);
+	}
+
+	return 0;
+}
+
+static int led_mcg_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct led_init_data init_data = {};
+	struct led_classdev *cdev;
+	struct mc_subled *subled;
+	struct led_mcg_priv *priv;
+	int i, count, ret;
+	unsigned int max_brightness;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	count = 0;
+	max_brightness = 0;
+	for (;;) {
+		struct led_classdev *led_cdev;
+
+		led_cdev = devm_of_led_get(dev, count);
+		if (IS_ERR(led_cdev)) {
+			/* Reached the end of the list ? */
+			if (PTR_ERR(led_cdev) == -ENOENT)
+				break;
+			return dev_err_probe(dev, PTR_ERR(led_cdev),
+					     "Unable to get led #%d", count);
+		}
+		count++;
+
+		priv->monochromatics = devm_krealloc(dev, priv->monochromatics,
+					count * sizeof(*priv->monochromatics),
+					GFP_KERNEL);
+		if (!priv->monochromatics)
+			return -ENOMEM;
+
+		priv->monochromatics[count - 1] = led_cdev;
+
+		max_brightness = max(max_brightness, led_cdev->max_brightness);
+	}
+
+	subled = devm_kzalloc(dev, count * sizeof(*subled), GFP_KERNEL);
+	if (!subled)
+		return -ENOMEM;
+	priv->mc_cdev.subled_info = subled;
+
+	for (i = 0; i < count; i++) {
+		struct led_classdev *led_cdev = priv->monochromatics[i];
+
+		subled[i].color_index = led_cdev->color;
+		/* configure the LED intensity to its maximum */
+		subled[i].intensity = max_brightness;
+	}
+
+	/* init the multicolor's LED class device */
+	cdev = &priv->mc_cdev.led_cdev;
+	cdev->flags = LED_CORE_SUSPENDRESUME;
+	cdev->brightness_set_blocking = led_mcg_set;
+	cdev->max_brightness = max_brightness;
+	cdev->color = LED_COLOR_ID_MULTI;
+	priv->mc_cdev.num_colors = count;
+
+	init_data.fwnode = dev_fwnode(dev);
+	ret = devm_led_classdev_multicolor_register_ext(dev, &priv->mc_cdev,
+							&init_data);
+	if (ret)
+		return dev_err_probe(dev, ret,
+			"failed to register multicolor led for %s.\n",
+			cdev->name);
+
+	ret = led_mcg_set(cdev, cdev->brightness);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "failed to set led value for %s.",
+				     cdev->name);
+
+	for (i = 0; i < count; i++) {
+		struct led_classdev *led_cdev = priv->monochromatics[i];
+
+		/* Make the sysfs of the monochromatic LED read-only */
+		led_cdev->flags |= LED_SYSFS_DISABLE;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id of_led_mcg_match[] = {
+	{ .compatible = "leds-group-multicolor" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, of_led_mcg_match);
+
+static struct platform_driver led_mcg_driver = {
+	.probe		= led_mcg_probe,
+	.driver		= {
+		.name	= "leds_group_multicolor",
+		.of_match_table = of_led_mcg_match,
+	}
+};
+module_platform_driver(led_mcg_driver);
+
+MODULE_AUTHOR("Jean-Jacques Hiblot <jjhiblot@traphandler.com>");
+MODULE_DESCRIPTION("multi-color LED group driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:leds-group-multicolor");
-- 
2.25.1

Re: [PATCH v3 3/4] dt-bindings: leds: Add binding for a multicolor group of LEDs

[Sascha Hauer]

On Wed, Aug 24, 2022 at 12:30:31PM +0200, Jean-Jacques Hiblot wrote:
> This allows to group multiple monochromatic LEDs into a multicolor
> LED, e.g. RGB LEDs.
> 
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
> Reviewed-by: Rob Herring <robh@kernel.org>
> ---
>  .../bindings/leds/leds-group-multicolor.yaml  | 61 +++++++++++++++++++
>  1 file changed, 61 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/leds-group-multicolor.yaml
> 
> diff --git a/Documentation/devicetree/bindings/leds/leds-group-multicolor.yaml b/Documentation/devicetree/bindings/leds/leds-group-multicolor.yaml
> new file mode 100644
> index 000000000000..79e5882a08e2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/leds-group-multicolor.yaml
> @@ -0,0 +1,61 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/leds-group-multicolor.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Multi-color LED built with monochromatic LEDs
> +
> +maintainers:
> +  - Jean-Jacques Hiblot <jjhiblot@traphandler.com>
> +
> +description: |
> +  This driver combines several monochromatic LEDs into one multi-color
> +  LED using the multicolor LED class.
> +
> +properties:
> +  compatible:
> +    const: leds-group-multicolor
> +
> +  leds:
> +    description:
> +      An aray of monochromatic leds
> +    $ref: /schemas/types.yaml#/definitions/phandle-array
> +
> +required:
> +  - leds
> +
> +allOf:
> +  - $ref: leds-class-multicolor.yaml#
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    #include <dt-bindings/leds/common.h>
> +
> +    monochromatic-leds {
> +        compatible = "gpio-leds";
> +
> +        led0: led-0 {
> +            gpios = <&mcu_pio 0 GPIO_ACTIVE_LOW>;
> +        };
> +
> +        led1: led-1 {
> +            gpios = <&mcu_pio 1 GPIO_ACTIVE_HIGH>;
> +        };
> +
> +        led2: led-2 {
> +            gpios = <&mcu_pio 1 GPIO_ACTIVE_HIGH>;
> +        };

led-2 has the same GPIO as led-1, should likely be <&mcu_pio 2 GPIO_ACTIVE_HIGH>;

> +    };
> +
> +    multi-led {
> +        compatible = "leds-group-multicolor";
> +        color = <LED_COLOR_ID_RGB>;
> +        function = LED_FUNCTION_INDICATOR;
> +        leds = <&led0>, <&led1>, <&led2>;
> +    };

When reading this I wondered how the driver knows which LED has which
color. Should you assign colors to the individual LEDs to make that
clear in the example?

Sascha

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Re: [PATCH v3 3/4] dt-bindings: leds: Add binding for a multicolor group of LEDs

[Jean-Jacques Hiblot]

On 24/08/2022 14:21, Sascha Hauer wrote:
> On Wed, Aug 24, 2022 at 12:30:31PM +0200, Jean-Jacques Hiblot wrote:
>> This allows to group multiple monochromatic LEDs into a multicolor
>> LED, e.g. RGB LEDs.
>>
>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com>
>> Reviewed-by: Rob Herring <robh@kernel.org>
>> ---
>>   .../bindings/leds/leds-group-multicolor.yaml  | 61 +++++++++++++++++++
>>   1 file changed, 61 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/leds/leds-group-multicolor.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/leds/leds-group-multicolor.yaml b/Documentation/devicetree/bindings/leds/leds-group-multicolor.yaml
>> new file mode 100644
>> index 000000000000..79e5882a08e2
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/leds/leds-group-multicolor.yaml
>> @@ -0,0 +1,61 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/leds/leds-group-multicolor.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Multi-color LED built with monochromatic LEDs
>> +
>> +maintainers:
>> +  - Jean-Jacques Hiblot <jjhiblot@traphandler.com>
>> +
>> +description: |
>> +  This driver combines several monochromatic LEDs into one multi-color
>> +  LED using the multicolor LED class.
>> +
>> +properties:
>> +  compatible:
>> +    const: leds-group-multicolor
>> +
>> +  leds:
>> +    description:
>> +      An aray of monochromatic leds
>> +    $ref: /schemas/types.yaml#/definitions/phandle-array
>> +
>> +required:
>> +  - leds
>> +
>> +allOf:
>> +  - $ref: leds-class-multicolor.yaml#
>> +
>> +unevaluatedProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/gpio/gpio.h>
>> +    #include <dt-bindings/leds/common.h>
>> +
>> +    monochromatic-leds {
>> +        compatible = "gpio-leds";
>> +
>> +        led0: led-0 {
>> +            gpios = <&mcu_pio 0 GPIO_ACTIVE_LOW>;
>> +        };
>> +
>> +        led1: led-1 {
>> +            gpios = <&mcu_pio 1 GPIO_ACTIVE_HIGH>;
>> +        };
>> +
>> +        led2: led-2 {
>> +            gpios = <&mcu_pio 1 GPIO_ACTIVE_HIGH>;
>> +        };
> led-2 has the same GPIO as led-1, should likely be <&mcu_pio 2 GPIO_ACTIVE_HIGH>;
ok.
>
>> +    };
>> +
>> +    multi-led {
>> +        compatible = "leds-group-multicolor";
>> +        color = <LED_COLOR_ID_RGB>;
>> +        function = LED_FUNCTION_INDICATOR;
>> +        leds = <&led0>, <&led1>, <&led2>;
>> +    };
> When reading this I wondered how the driver knows which LED has which
> color. Should you assign colors to the individual LEDs to make that
> clear in the example?

Good point. I'll add this to the example. Thanks.

JJ

>
> Sascha
>