[PATCH 0/2] New multiple GPIOs LED driver

[PATCH 0/2] New multiple GPIOs LED driver

[Hermes Zhang]

From: Hermes Zhang <chenhuiz@axis.com>

*** BLURB HERE ***

New multiple GPIOs LED driver


Hermes Zhang (2):
  leds: leds-multi-gpio: Add multiple GPIOs LED driver
  dt-binding: leds: Document leds-multi-gpio bindings

 .../bindings/leds/leds-multi-gpio.yaml        |  50 +++++++
 drivers/leds/Kconfig                          |  12 ++
 drivers/leds/Makefile                         |   1 +
 drivers/leds/leds-multi-gpio.c                | 140 ++++++++++++++++++
 4 files changed, 203 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-multi-gpio.yaml
 create mode 100644 drivers/leds/leds-multi-gpio.c

-- 
2.20.1

[PATCH 1/2] leds: leds-multi-gpio: Add multiple GPIOs LED driver

[Hermes Zhang]

From: Hermes Zhang <chenhuiz@axis.com>

Introduce a new multiple GPIOs LED driver. This LED will made of
multiple GPIOs (up to 8) and will map different brightness to different
GPIOs states which defined in dts file.

Signed-off-by: Hermes Zhang <chenhuiz@axis.com>
---
 drivers/leds/Kconfig           |  12 +++
 drivers/leds/Makefile          |   1 +
 drivers/leds/leds-multi-gpio.c | 140 +++++++++++++++++++++++++++++++++
 3 files changed, 153 insertions(+)
 create mode 100644 drivers/leds/leds-multi-gpio.c

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index b6742b4231bf..e3ff84080192 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -370,6 +370,18 @@ config LEDS_GPIO
 	  defined as platform devices and/or OpenFirmware platform devices.
 	  The code to use these bindings can be selected below.
 
+config LEDS_MULTI_GPIO
+	tristate "LED Support for multiple GPIOs LED"
+	depends on LEDS_CLASS
+	depends on GPIOLIB
+	help
+	  This option enables support for a multiple GPIOs LED. Such LED is made
+	  of multiple GPIOs and could change the brightness by setting different
+	  states of the GPIOs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called leds-multi-gpio.
+
 config LEDS_LP3944
 	tristate "LED Support for N.S. LP3944 (Fun Light) I2C chip"
 	depends on LEDS_CLASS
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 2a698df9da57..984201ec5375 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_LEDS_DA903X)		+= leds-da903x.o
 obj-$(CONFIG_LEDS_DA9052)		+= leds-da9052.o
 obj-$(CONFIG_LEDS_FSG)			+= leds-fsg.o
 obj-$(CONFIG_LEDS_GPIO)			+= leds-gpio.o
+obj-$(CONFIG_LEDS_MULTI_GPIO)		+= leds-multi-gpio.o
 obj-$(CONFIG_LEDS_GPIO_REGISTER)	+= leds-gpio-register.o
 obj-$(CONFIG_LEDS_HP6XX)		+= leds-hp6xx.o
 obj-$(CONFIG_LEDS_INTEL_SS4200)		+= leds-ss4200.o
diff --git a/drivers/leds/leds-multi-gpio.c b/drivers/leds/leds-multi-gpio.c
new file mode 100644
index 000000000000..54d92c81a476
--- /dev/null
+++ b/drivers/leds/leds-multi-gpio.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Axis Communications AB
+ */
+
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/kernel.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+
+#define MAX_GPIO_NUM  8
+
+struct multi_gpio_led_priv {
+	struct led_classdev cdev;
+
+	struct gpio_descs *gpios;
+
+	u8 *states;
+	int nr_states;
+};
+
+
+static void multi_gpio_led_set(struct led_classdev *led_cdev,
+	enum led_brightness value)
+{
+	struct multi_gpio_led_priv *priv;
+	int idx;
+
+	DECLARE_BITMAP(values, MAX_GPIO_NUM);
+
+	priv = container_of(led_cdev, struct multi_gpio_led_priv, cdev);
+
+	idx = (value - LED_OFF) * priv->nr_states / (LED_FULL + 1);
+
+	values[0] = priv->states[idx];
+
+	gpiod_set_array_value(priv->gpios->ndescs, priv->gpios->desc,
+	    priv->gpios->info, values);
+}
+
+static int multi_gpio_led_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node;
+	struct multi_gpio_led_priv *priv = NULL;
+	int ret;
+	const char *state = NULL;
+	struct led_init_data init_data = {};
+
+	priv = devm_kzalloc(dev, sizeof(struct multi_gpio_led_priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->gpios = devm_gpiod_get_array(dev, "led", GPIOD_OUT_LOW);
+	if (IS_ERR(priv->gpios))
+		return PTR_ERR(priv->gpios);
+
+	if (priv->gpios->ndescs >= MAX_GPIO_NUM) {
+		dev_err(dev, "Too many GPIOs\n");
+		return -EINVAL;
+	}
+
+	ret = of_property_count_u8_elems(node, "led-states");
+	if (ret < 0)
+		return ret;
+
+	priv->nr_states = ret;
+	priv->states = devm_kzalloc(dev, sizeof(*priv->states) * priv->nr_states, GFP_KERNEL);
+	if (!priv->states)
+		return -ENOMEM;
+
+	ret = of_property_read_u8_array(node, "led-states", priv->states, priv->nr_states);
+	if (ret)
+		return ret;
+
+	priv->cdev.max_brightness = LED_FULL;
+	priv->cdev.default_trigger = of_get_property(node, "linux,default-trigger", NULL);
+	priv->cdev.brightness_set = multi_gpio_led_set;
+
+	init_data.fwnode = of_fwnode_handle(node);
+
+	ret = devm_led_classdev_register_ext(dev, &priv->cdev, &init_data);
+	if (ret < 0)
+		return ret;
+
+	of_property_read_string(node, "default-state", &state);
+	if (!strcmp(state, "on"))
+		multi_gpio_led_set(&priv->cdev, LED_FULL);
+	else
+		multi_gpio_led_set(&priv->cdev, LED_OFF);
+
+	platform_set_drvdata(pdev, priv);
+
+	return 0;
+}
+
+static void multi_gpio_led_shutdown(struct platform_device *pdev)
+{
+	struct multi_gpio_led_priv *priv = platform_get_drvdata(pdev);
+
+	multi_gpio_led_set(&priv->cdev, LED_OFF);
+}
+
+static int multi_gpio_led_remove(struct platform_device *pdev)
+{
+	multi_gpio_led_shutdown(pdev);
+
+	return 0;
+}
+
+static const struct of_device_id of_multi_gpio_led_match[] = {
+	{ .compatible = "multi-gpio-led", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, of_multi_gpio_led_match);
+
+static struct platform_driver multi_gpio_led_driver = {
+	.probe		= multi_gpio_led_probe,
+	.remove		= multi_gpio_led_remove,
+	.shutdown	= multi_gpio_led_shutdown,
+	.driver		= {
+		.name	= "multi-gpio-led",
+		.of_match_table = of_multi_gpio_led_match,
+	},
+};
+
+module_platform_driver(multi_gpio_led_driver);
+
+MODULE_AUTHOR("Hermes Zhang <chenhui.zhang@axis.com>");
+MODULE_DESCRIPTION("Multiple GPIOs LED driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:leds-multi-gpio");
-- 
2.20.1

Re: [PATCH 1/2] leds: leds-multi-gpio: Add multiple GPIOs LED driver

[Marek Behun]

On Wed, 24 Mar 2021 15:56:30 +0800
Hermes Zhang <chenhui.zhang@axis.com> wrote:

> From: Hermes Zhang <chenhuiz@axis.com>
> 
> Introduce a new multiple GPIOs LED driver. This LED will made of
> multiple GPIOs (up to 8) and will map different brightness to different
> GPIOs states which defined in dts file.

I wonder how many boards have such LEDs.

Also if it wouldn't be better to expand the original leds-gpio driver.
Probably depends on how much larger would such expansion make the
leds-gpio driver.

> +#include <linux/err.h>
> +#include <linux/gpio.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/kernel.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_gpio.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +#include <linux/slab.h>

Why do you include slab.h?

> +
> +#define MAX_GPIO_NUM  8
> +
> +struct multi_gpio_led_priv {
> +	struct led_classdev cdev;
> +
> +	struct gpio_descs *gpios;
> +
> +	u8 *states;
> +	int nr_states;
> +};

Use flexible array members. Allocate with
  devm_kzalloc(dev, struct_size(priv, states, priv->nr_states),
               GFP_KERNEL)

> +
> +
> +static void multi_gpio_led_set(struct led_classdev *led_cdev,
> +	enum led_brightness value)
> +{
> +	struct multi_gpio_led_priv *priv;
> +	int idx;
> +
> +	DECLARE_BITMAP(values, MAX_GPIO_NUM);
> +
> +	priv = container_of(led_cdev, struct multi_gpio_led_priv, cdev);
> +
> +	idx = (value - LED_OFF) * priv->nr_states / (LED_FULL + 1);

LED_FULL / LED_OFF are deprecated, don't use them.

> +
> +	values[0] = priv->states[idx];
> +
> +	gpiod_set_array_value(priv->gpios->ndescs, priv->gpios->desc,
> +	    priv->gpios->info, values);
> +}
> +
> +static int multi_gpio_led_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *node = dev->of_node;
> +	struct multi_gpio_led_priv *priv = NULL;
> +	int ret;
> +	const char *state = NULL;
> +	struct led_init_data init_data = {};
> +
> +	priv = devm_kzalloc(dev, sizeof(struct multi_gpio_led_priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->gpios = devm_gpiod_get_array(dev, "led", GPIOD_OUT_LOW);
> +	if (IS_ERR(priv->gpios))
> +		return PTR_ERR(priv->gpios);
> +
> +	if (priv->gpios->ndescs >= MAX_GPIO_NUM) {
> +		dev_err(dev, "Too many GPIOs\n");
> +		return -EINVAL;
> +	}
> +
> +	ret = of_property_count_u8_elems(node, "led-states");
> +	if (ret < 0)
> +		return ret;
> +
> +	priv->nr_states = ret;
> +	priv->states = devm_kzalloc(dev, sizeof(*priv->states) * priv->nr_states, GFP_KERNEL);
> +	if (!priv->states)
> +		return -ENOMEM;
> +
> +	ret = of_property_read_u8_array(node, "led-states", priv->states, priv->nr_states);
> +	if (ret)
> +		return ret;
> +
> +	priv->cdev.max_brightness = LED_FULL;

???? max_brightness is not 255 (= LED_FULL). max_brightness must be
derived from the led-states property.


> +	priv->cdev.default_trigger = of_get_property(node, "linux,default-trigger", NULL);
> +	priv->cdev.brightness_set = multi_gpio_led_set;
> +
> +	init_data.fwnode = of_fwnode_handle(node);
> +
> +	ret = devm_led_classdev_register_ext(dev, &priv->cdev, &init_data);
> +	if (ret < 0)
> +		return ret;
> +
> +	of_property_read_string(node, "default-state", &state);
> +	if (!strcmp(state, "on"))
> +		multi_gpio_led_set(&priv->cdev, LED_FULL);
> +	else
> +		multi_gpio_led_set(&priv->cdev, LED_OFF);

Again LED_FULL and LED_OFF...
What about default-state = "keep" ?

Hermes, do you actually have a device that controls LEDs this way? How
many brightness options do they have?

Also I think this functionality could be easily incorporated into the
existing leds-gpio driver, instead of creating new driver.

Moreover your driver can control only one LED, so it needs to be
probed multiple times for multiple LEDs. Meanwhile the leds-gpio driver
can register multiple LEDs in one probe...

Marek

Re: [PATCH 1/2] leds: leds-multi-gpio: Add multiple GPIOs LED driver

[Pavel Machek]

[-- Attachment #1: Type: text/plain, Size: 1410 bytes --]

Hi!

> > From: Hermes Zhang <chenhuiz@axis.com>
> > 
> > Introduce a new multiple GPIOs LED driver. This LED will made of
> > multiple GPIOs (up to 8) and will map different brightness to different
> > GPIOs states which defined in dts file.
> 
> I wonder how many boards have such LEDs.
> 
> Also if it wouldn't be better to expand the original leds-gpio driver.
> Probably depends on how much larger would such expansion make the
> leds-gpio driver.

Let's start with separate.

> Use flexible array members. Allocate with
>   devm_kzalloc(dev, struct_size(priv, states, priv->nr_states),
>                GFP_KERNEL)

Better yet, assume the brightness is 0..2^(num leds) and avoid this
complexity.

> Again LED_FULL and LED_OFF...
> What about default-state = "keep" ?
> 
> Hermes, do you actually have a device that controls LEDs this way? How
> many brightness options do they have?

He has two bits.

> Also I think this functionality could be easily incorporated into the
> existing leds-gpio driver, instead of creating new driver.

> Moreover your driver can control only one LED, so it needs to be
> probed multiple times for multiple LEDs. Meanwhile the leds-gpio driver
> can register multiple LEDs in one probe...

The current version is mostly fine. Let's not overcomplicate it.

Best regards,
								Pavel
-- 
http://www.livejournal.com/~pavelmachek

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Re: [PATCH 1/2] leds: leds-multi-gpio: Add multiple GPIOs LED driver

[Pavel Machek]

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Hi!

> > +	of_property_read_string(node, "default-state", &state);
> > +	if (!strcmp(state, "on"))
> > +		multi_gpio_led_set(&priv->cdev, LED_FULL);
> > +	else
> > +		multi_gpio_led_set(&priv->cdev, LED_OFF);
> 
> Again LED_FULL and LED_OFF...
> What about default-state = "keep" ?

Let's not support default-state unless you need it.

Best regards,
							Pavel
-- 
http://www.livejournal.com/~pavelmachek

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Re: [PATCH 1/2] leds: leds-multi-gpio: Add multiple GPIOs LED driver

[Hermes Zhang]

Hi Marek,

On 3/24/21 5:34 PM, Marek Behun wrote:
>> +#include <linux/err.h>
>> +#include <linux/gpio.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/kernel.h>
>> +#include <linux/leds.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_gpio.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/property.h>
>> +#include <linux/slab.h>
> Why do you include slab.h?
Yeah, I will clean it in next commit.
>> +
>> +
>> +static void multi_gpio_led_set(struct led_classdev *led_cdev,
>> +	enum led_brightness value)
>> +{
>> +	struct multi_gpio_led_priv *priv;
>> +	int idx;
>> +
>> +	DECLARE_BITMAP(values, MAX_GPIO_NUM);
>> +
>> +	priv = container_of(led_cdev, struct multi_gpio_led_priv, cdev);
>> +
>> +	idx = (value - LED_OFF) * priv->nr_states / (LED_FULL + 1);
> LED_FULL / LED_OFF are deprecated, don't use them.

Then could I use just 0 (instead LED_OFF) and led_cdev->max_brightness

(instead of LED_FULL) here? The idea here is map the states defined in dts

to the full brightness range.

> +
> +	priv->nr_states = ret;
> +	priv->states = devm_kzalloc(dev, sizeof(*priv->states) * priv->nr_states, GFP_KERNEL);
> +	if (!priv->states)
> +		return -ENOMEM;
> +
> +	ret = of_property_read_u8_array(node, "led-states", priv->states, priv->nr_states);
> +	if (ret)
> +		return ret;
> +
> +	priv->cdev.max_brightness = LED_FULL;
> ???? max_brightness is not 255 (= LED_FULL). max_brightness must be
> derived from the led-states property.

Yeah, I will fix this. the max-brightness should for the whole LED,
right? So

it will at same level with led-states.

Re: [PATCH 1/2] leds: leds-multi-gpio: Add multiple GPIOs LED driver

[Marek Behun]

On Thu, 25 Mar 2021 06:04:43 +0000
Hermes Zhang <Hermes.Zhang@axis.com> wrote:

> > LED_FULL / LED_OFF are deprecated, don't use them.  
> 
> Then could I use just 0 (instead LED_OFF) and led_cdev->max_brightness
> 
> (instead of LED_FULL) here? The idea here is map the states defined in dts
> 
> to the full brightness range.

Yes, you can and should use 0 insted of LED_OFF.

> > +	priv->cdev.max_brightness = LED_FULL;
> > ???? max_brightness is not 255 (= LED_FULL). max_brightness must be
> > derived from the led-states property.  
> 
> Yeah, I will fix this. the max-brightness should for the whole LED,
> right? So
> 
> it will at same level with led-states.

max_brightness should be (the number of states - 1). I.e. if you have 4
gpios and the LED supports full 2^4 = 16 states, max brightness should
be 15.

Marek

Re: [PATCH 1/2] leds: leds-multi-gpio: Add multiple GPIOs LED driver

[Pavel Machek]

[-- Attachment #1: Type: text/plain, Size: 746 bytes --]

On Wed 2021-03-24 15:56:30, Hermes Zhang wrote:
> From: Hermes Zhang <chenhuiz@axis.com>
> 
> Introduce a new multiple GPIOs LED driver. This LED will made of
> multiple GPIOs (up to 8) and will map different brightness to different
> GPIOs states which defined in dts file.
> 
> Signed-off-by: Hermes Zhang <chenhuiz@axis.com>
> ---
>  drivers/leds/Kconfig           |  12 +++
>  drivers/leds/Makefile          |   1 +
>  drivers/leds/leds-multi-gpio.c | 140 +++++++++++++++++++++++++++++++++
>  3 files changed, 153 insertions(+)
>  create mode 100644 drivers/leds/leds-multi-gpio.c

Let's put it into drivers/leds/simple. You may need to create it.

Best regards,
								Pavel
-- 
http://www.livejournal.com/~pavelmachek

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[PATCH 2/2] dt-binding: leds: Document leds-multi-gpio bindings

[Hermes Zhang]

From: Hermes Zhang <chenhuiz@axis.com>

Document the device tree bindings of the multiple GPIOs LED driver
Documentation/devicetree/bindings/leds/leds-multi-gpio.yaml.

Signed-off-by: Hermes Zhang <chenhuiz@axis.com>
---
 .../bindings/leds/leds-multi-gpio.yaml        | 50 +++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-multi-gpio.yaml

diff --git a/Documentation/devicetree/bindings/leds/leds-multi-gpio.yaml b/Documentation/devicetree/bindings/leds/leds-multi-gpio.yaml
new file mode 100644
index 000000000000..6f2b47487b90
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/leds-multi-gpio.yaml
@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/leds-multi-gpio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Multiple GPIOs LED driver
+
+maintainers:
+  - Hermes Zhang <chenhuiz@axis.com>
+
+description:
+  This will support some LED made of multiple GPIOs and the brightness of the
+  LED could map to different states of the GPIOs.
+
+properties:
+  compatible:
+    const: multi-gpio-led
+
+  led-gpios:
+    description: Array of one or more GPIOs pins used to control the LED.
+    minItems: 1
+    maxItems: 8  # Should be enough
+
+  led-states:
+    description: |
+      The array list the supported states here which will map to brightness
+      from 0 to maximum. Each item in the array will present all the GPIOs
+      value by bit.
+    $ref: /schemas/types.yaml#/definitions/uint8-array
+    minItems: 1
+    maxItems: 16 # Should be enough
+
+required:
+  - compatible
+  - led-gpios
+  - led-states
+
+additionalProperties: false
+
+examples:
+  - |
+    gpios-led {
+      compatible = "multi-gpio-led";
+
+      led-gpios = <&gpio0 23 0x1>,
+                  <&gpio0 24 0x1>;
+      led-states = /bits/ 8 <0x00 0x01 0x02 0x03>;
+    };
+...
-- 
2.20.1

Re: [PATCH 2/2] dt-binding: leds: Document leds-multi-gpio bindings

[Marek Behun]

On Wed, 24 Mar 2021 15:56:31 +0800
Hermes Zhang <chenhui.zhang@axis.com> wrote:

> From: Hermes Zhang <chenhuiz@axis.com>
> 
> Document the device tree bindings of the multiple GPIOs LED driver
> Documentation/devicetree/bindings/leds/leds-multi-gpio.yaml.

The dt-binding should come before the actual driver. Otherwise there
will be a commit with the driver existing but no documentation for its
bindings.

> +description:
> +  This will support some LED made of multiple GPIOs and the brightness of the
> +  LED could map to different states of the GPIOs.

Don't use future tense. Don't mention drivers in device tree
binding documentation, if it can be helped. The device tree binding
documentation should describe devices and their nodes... (and I see
that I did a similar mistake for the cznic,turris-omnia-leds.yaml
binding, I will have to fix that).

Instead the description should be something like this:
  This binding represents LED devices which are controller with
  multiple GPIO lines in order to achieve more than two brightness
  states.
  

> +
> +properties:
> +  compatible:
> +    const: multi-gpio-led
> +
> +  led-gpios:
> +    description: Array of one or more GPIOs pins used to control the LED.
> +    minItems: 1
> +    maxItems: 8  # Should be enough
> +
> +  led-states:
> +    description: |
> +      The array list the supported states here which will map to brightness
> +      from 0 to maximum. Each item in the array will present all the GPIOs
> +      value by bit.

Again future tense...

> +    $ref: /schemas/types.yaml#/definitions/uint8-array
> +    minItems: 1
> +    maxItems: 16 # Should be enough
> +
> +required:
> +  - compatible
> +  - led-gpios
> +  - led-states
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    gpios-led {
> +      compatible = "multi-gpio-led";
> +
> +      led-gpios = <&gpio0 23 0x1>,
> +                  <&gpio0 24 0x1>;
> +      led-states = /bits/ 8 <0x00 0x01 0x02 0x03>;
> +    };
> +...

Re: [PATCH 2/2] dt-binding: leds: Document leds-multi-gpio bindings

[Vesa Jääskeläinen]

Hi,

See below.

On 24.3.2021 9.56, Hermes Zhang wrote:
> From: Hermes Zhang <chenhuiz@axis.com>
> 
> Document the device tree bindings of the multiple GPIOs LED driver
> Documentation/devicetree/bindings/leds/leds-multi-gpio.yaml.
> 
> Signed-off-by: Hermes Zhang <chenhuiz@axis.com>
> ---
>   .../bindings/leds/leds-multi-gpio.yaml        | 50 +++++++++++++++++++
>   1 file changed, 50 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/leds/leds-multi-gpio.yaml
> 
> diff --git a/Documentation/devicetree/bindings/leds/leds-multi-gpio.yaml b/Documentation/devicetree/bindings/leds/leds-multi-gpio.yaml
> new file mode 100644
> index 000000000000..6f2b47487b90
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/leds-multi-gpio.yaml
> @@ -0,0 +1,50 @@
> +# SPDX-License-Identifier: GPL-2.0
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/leds-multi-gpio.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Multiple GPIOs LED driver
> +
> +maintainers:
> +  - Hermes Zhang <chenhuiz@axis.com>
> +
> +description:
> +  This will support some LED made of multiple GPIOs and the brightness of the
> +  LED could map to different states of the GPIOs.
> +
> +properties:
> +  compatible:
> +    const: multi-gpio-led
> +
> +  led-gpios:
> +    description: Array of one or more GPIOs pins used to control the LED.
> +    minItems: 1
> +    maxItems: 8  # Should be enough

We also have a case with multi color LEDs (which is probably a more 
common than multi intensity LED. So I am wondering how these both could 
co-exist.

From: 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/leds/leds-gpio.yaml?h=v5.12-rc4#n58

         led-0 {
             gpios = <&mcu_pio 0 GPIO_ACTIVE_LOW>;
             linux,default-trigger = "disk-activity";
             function = LED_FUNCTION_DISK;
         };

Now 'gpios' (and in LED context) and 'led-gpios' is very close to each 
other and could easily be confused.

Perhaps this could be something like:

intensity-gpios = ...

or even simplified then just to gpios = <...>

> +
> +  led-states:
> +    description: |
> +      The array list the supported states here which will map to brightness
> +      from 0 to maximum. Each item in the array will present all the GPIOs
> +      value by bit.
> +    $ref: /schemas/types.yaml#/definitions/uint8-array
> +    minItems: 1
> +    maxItems: 16 # Should be enough
> +
> +required:
> +  - compatible
> +  - led-gpios
> +  - led-states
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    gpios-led {
> +      compatible = "multi-gpio-led";
> +
> +      led-gpios = <&gpio0 23 0x1>,
> +                  <&gpio0 24 0x1>;
> +      led-states = /bits/ 8 <0x00 0x01 0x02 0x03>;
> +    };
> +...
> 

From: 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/leds/leds-lp55xx.yaml?h=v5.12-rc4#n196

There is example of multi color LED configuration. In example below I 
used two-color LED with red and green as an example (which what we seem 
to have most in use).

Then if try to combine these into something like:

# Multi color LED with single GPIO line per color
multi-led@2 {
   compatible = "gpio-leds";
   color = <LED_COLOR_ID_MULTICOLOR>;
   led@0 {
     color = <LED_COLOR_ID_GREEN>;
     gpios = <&mcu_pio 0 GPIO_ACTIVE_LOW>;
   };

   led@1 {
     color = <LED_COLOR_ID_RED>;
     gpios = <&mcu_pio 1 GPIO_ACTIVE_LOW>;
   };
};

# And with intensity GPIOs:
multi-led@2 {
   compatible = "gpio-leds";
   color = <LED_COLOR_ID_MULTICOLOR>;

   led@0 {
     color = <LED_COLOR_ID_GREEN>;
     gpios = <&gpio0 23 0x1>,
             <&gpio0 24 0x1>;
     ... see below
   };

   led@1 {
     color = <LED_COLOR_ID_RED>;
     gpios = <&gpio0 25 0x1>,
             <&gpio0 26 0x1>;
     ... see below
   };
};

# And then single GPIO with intensity GPIOs:
led@2 {
   compatible = "gpio-leds";
   gpios = <&gpio0 23 0x1>,
           <&gpio0 24 0x1>;
   gpios-brightness-levels = <0 1 2 3>
};

I changed 'led-states' to 'gpios-brightness-levels' as it describe more 
that this is about brightness and not some other state information.

How would this sound?

Thanks,
Vesa Jääskeläinen

Re: [PATCH 2/2] dt-binding: leds: Document leds-multi-gpio bindings

[Pavel Machek]

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Hi!

> See below.

Please trim.

> > +  led-gpios:
> > +    description: Array of one or more GPIOs pins used to control the LED.
> > +    minItems: 1
> > +    maxItems: 8  # Should be enough
> 
> We also have a case with multi color LEDs (which is probably a more common
> than multi intensity LED. So I am wondering how these both could co-exist.
> 
> From: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/leds/leds-gpio.yaml?h=v5.12-rc4#n58
> 
>         led-0 {
>             gpios = <&mcu_pio 0 GPIO_ACTIVE_LOW>;
>             linux,default-trigger = "disk-activity";
>             function = LED_FUNCTION_DISK;
>         };
> 
> Now 'gpios' (and in LED context) and 'led-gpios' is very close to each other
> and could easily be confused.
> 
> Perhaps this could be something like:
> 
> intensity-gpios = ...
> 
> or even simplified then just to gpios = <...>

...
> How would this sound?

Well, not too bad on a quick look.

Are you willing to implement such multi-color-multi-bit-multi-gpio
driver?

Best regards,
								Pavel
-- 
http://www.livejournal.com/~pavelmachek

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Re: [PATCH 2/2] dt-binding: leds: Document leds-multi-gpio bindings

[Vesa Jääskeläinen]

Hi,

On 25.3.2021 20.41, Pavel Machek wrote:
>>> +  led-gpios:
>>> +    description: Array of one or more GPIOs pins used to control the LED.
>>> +    minItems: 1
>>> +    maxItems: 8  # Should be enough
>>
>> We also have a case with multi color LEDs (which is probably a more common
>> than multi intensity LED. So I am wondering how these both could co-exist.
>>
>> From: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/leds/leds-gpio.yaml?h=v5.12-rc4#n58
>>
>>          led-0 {
>>              gpios = <&mcu_pio 0 GPIO_ACTIVE_LOW>;
>>              linux,default-trigger = "disk-activity";
>>              function = LED_FUNCTION_DISK;
>>          };
>>
>> Now 'gpios' (and in LED context) and 'led-gpios' is very close to each other
>> and could easily be confused.
>>
>> Perhaps this could be something like:
>>
>> intensity-gpios = ...
>>
>> or even simplified then just to gpios = <...>
> 
> ...
>> How would this sound?
> 
> Well, not too bad on a quick look.
> 
> Are you willing to implement such multi-color-multi-bit-multi-gpio
> driver?

We have a need for multi color GPIO LED support so I can work on that if 
no one else gets there before me -- I do not have hardware with multiple 
GPIO lines controlling the brightness so that needs a bit more effort in 
order to test that out.

At some point of time I could also revive the PWM stuff if no one else 
beats me to it -- but probably the GPIO variant is easier to get done as 
binary states are easier.

Thanks,
Vesa Jääskeläinen

Re: [PATCH 0/2] New multiple GPIOs LED driver

[Marek Behun]

On Wed, 24 Mar 2021 15:56:29 +0800
Hermes Zhang <chenhui.zhang@axis.com> wrote:

> From: Hermes Zhang <chenhuiz@axis.com>
> 
> *** BLURB HERE ***

"*** BLURB HERE ***" is meant to be substituted with your text :)

All in all I think you are adding functionality which can be
incorporated simply into the existing leds-gpio driver instead of new
driver.

Marek