[PATCH v9 1/2] dt: bindings: lm3692x: Add bindings for lm3692x LED driver

[PATCH v9 1/2] dt: bindings: lm3692x: Add bindings for lm3692x LED driver

[Dan Murphy]

This adds the devicetree bindings for the LM3692x
I2C LED string driver.

Acked-by: Pavel Machek <pavel-+ZI9xUNit7I@public.gmane.org>
Signed-off-by: Dan Murphy <dmurphy-l0cyMroinI0@public.gmane.org>
---

v9 - Moved 2 nodes to Optional Child and renamed node names to device type
https://patchwork.kernel.org/patch/10093757/

v8 - Added address-cells and size-cells as well as child node reg - https://patchwork.kernel.org/patch/10091259/
v7 - No changes - https://patchwork.kernel.org/patch/10087475/
v6 - No changes -https://patchwork.kernel.org/patch/10085567/
v5 - No Changes - https://patchwork.kernel.org/patch/10081071/
v4 - Fix example node, added trigger entry, removed ambiguous x for compatible and
added common.txt pointer for label - https://patchwork.kernel.org/patch/10060107
v3 - No changes
v2 - No changes - https://patchwork.kernel.org/patch/10056677/

 .../devicetree/bindings/leds/leds-lm3692x.txt      | 49 ++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-lm3692x.txt

diff --git a/Documentation/devicetree/bindings/leds/leds-lm3692x.txt b/Documentation/devicetree/bindings/leds/leds-lm3692x.txt
new file mode 100644
index 000000000000..a93e19edfb42
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/leds-lm3692x.txt
@@ -0,0 +1,49 @@
+* Texas Instruments - LM3692x Highly Efficient White LED Driver
+
+The LM3692x is an ultra-compact, highly efficient,
+white-LED driver designed for LCD display backlighting.
+
+The main difference between the LM36922 and LM36923 is the number of
+LED strings it supports.  The LM36922 supports two strings while the LM36923
+supports three strings.
+
+Required properties:
+	- compatible:
+		"ti,lm36922"
+		"ti,lm36923"
+	- reg :  I2C slave address
+	- #address-cells : 1
+	- #size-cells : 0
+
+Optional properties:
+	- enable-gpios : gpio pin to enable/disable the device.
+	- vled-supply : LED supply
+
+Required child properties:
+	- reg : 0
+
+Optional child properties:
+	- label : see Documentation/devicetree/bindings/leds/common.txt
+	- linux,default-trigger :
+	   see Documentation/devicetree/bindings/leds/common.txt
+
+Example:
+
+led-controller@36 {
+	compatible = "ti,lm3692x";
+	reg = <0x36>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	enable-gpios = <&gpio1 28 GPIO_ACTIVE_HIGH>;
+	vled-supply = <&vbatt>;
+
+	led@0 {
+		reg = <0>;
+		label = "backlight_cluster";
+		linux,default-trigger = "backlight";
+	};
+}
+
+For more product information please see the link below:
+http://www.ti.com/lit/ds/snvsa29/snvsa29.pdf
-- 
2.15.0.124.g7668cbc60

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[PATCH v9 2/2] leds: lm3692x: Introduce LM3692x dual string driver

[Dan Murphy]

Introducing the LM3692x Dual-String white LED driver.

Data sheet is located
http://www.ti.com/lit/ds/snvsa29/snvsa29.pdf

Signed-off-by: Dan Murphy <dmurphy-l0cyMroinI0@public.gmane.org>
---

v9 - Change the no DT label case to pull the device name from the i2c_id struct
so that the device name can be part of the sysfs node - https://patchwork.kernel.org/patch/10093759/

v8 - No changes
v7 - Reverted back to creating the LED label within the driver -
https://patchwork.kernel.org/patch/10087473/
v6 - Use new LED API to compose LED label as opposed to creating it. -
https://patchwork.kernel.org/patch/10085565/
v5 - Added OF dependency in Kconfig, added extra fault flag read to ensure that
if a fault exists and it is not a artifact, fixed LED class label to be derived
from either the DT child "label" node or create a label based on 
parent_node_name:led color:trigger, removed ifdef for CONFIG_OF and removed
of_match_ptr - https://patchwork.kernel.org/patch/10081073/
v4 - Converted to devm led class register, changed MODULE_LICENSE to GPL v2, 
set the led name based on child node name or label entry, removed fault and
returned read_buf for fault checking, added mutex_destroy to remove function,
and removed LED_FULL - https://patchwork.kernel.org/patch/10060109/
v3 - Add missing Makefile and Kconfig from v1 and v2 - https://patchwork.kernel.org/patch/10060075/
v2 - Added data sheet link, fixed linuxdoc format, returned on failure in init
routine, return on fault_check failure, updated brightness calculation and
fixed capitalization issue - https://patchwork.kernel.org/patch/10056675/

 drivers/leds/Kconfig        |   7 +
 drivers/leds/Makefile       |   1 +
 drivers/leds/leds-lm3692x.c | 393 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 401 insertions(+)
 create mode 100644 drivers/leds/leds-lm3692x.c

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 318a28fd58fe..1d215b39cefd 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -137,6 +137,13 @@ config LEDS_LM3642
 	  converter plus 1.5A constant current driver for a high-current
 	  white LED.
 
+config LEDS_LM3692X
+	tristate "LED support for LM3692x Chips"
+	depends on LEDS_CLASS && I2C && OF
+	select REGMAP_I2C
+	help
+	  This option enables support for the TI LM3692x family
+	  of white LED string drivers used for backlighting.
 
 config LEDS_LOCOMO
 	tristate "LED Support for Locomo device"
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index a2a6b5a4f86d..987884a5b9a5 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -74,6 +74,7 @@ obj-$(CONFIG_LEDS_PM8058)		+= leds-pm8058.o
 obj-$(CONFIG_LEDS_MLXCPLD)		+= leds-mlxcpld.o
 obj-$(CONFIG_LEDS_NIC78BX)		+= leds-nic78bx.o
 obj-$(CONFIG_LEDS_MT6323)		+= leds-mt6323.o
+obj-$(CONFIG_LEDS_LM3692X)		+= leds-lm3692x.o
 
 # LED SPI Drivers
 obj-$(CONFIG_LEDS_DAC124S085)		+= leds-dac124s085.o
diff --git a/drivers/leds/leds-lm3692x.c b/drivers/leds/leds-lm3692x.c
new file mode 100644
index 000000000000..7077f9459bce
--- /dev/null
+++ b/drivers/leds/leds-lm3692x.c
@@ -0,0 +1,393 @@
+/*
+ * TI lm3692x LED Driver
+ *
+ * Copyright (C) 2017 Texas Instruments
+ *
+ * Author: Dan Murphy <dmurphy-l0cyMroinI0@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * Data sheet is located
+ * http://www.ti.com/lit/ds/snvsa29/snvsa29.pdf
+ */
+
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/leds.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/slab.h>
+#include <uapi/linux/uleds.h>
+
+#define LM3692X_REV		0x0
+#define LM3692X_RESET		0x1
+#define LM3692X_EN		0x10
+#define LM3692X_BRT_CTRL	0x11
+#define LM3692X_PWM_CTRL	0x12
+#define LM3692X_BOOST_CTRL	0x13
+#define LM3692X_AUTO_FREQ_HI	0x15
+#define LM3692X_AUTO_FREQ_LO	0x16
+#define LM3692X_BL_ADJ_THRESH	0x17
+#define LM3692X_BRT_LSB		0x18
+#define LM3692X_BRT_MSB		0x19
+#define LM3692X_FAULT_CTRL	0x1e
+#define LM3692X_FAULT_FLAGS	0x1f
+
+#define LM3692X_SW_RESET	BIT(0)
+#define LM3692X_DEVICE_EN	BIT(0)
+#define LM3692X_LED1_EN		BIT(1)
+#define LM3692X_LED2_EN		BIT(2)
+
+/* Brightness Control Bits */
+#define LM3692X_BL_ADJ_POL	BIT(0)
+#define LM3692X_RAMP_RATE_125us	0x00
+#define LM3692X_RAMP_RATE_250us	BIT(1)
+#define LM3692X_RAMP_RATE_500us BIT(2)
+#define LM3692X_RAMP_RATE_1ms	(BIT(1) | BIT(2))
+#define LM3692X_RAMP_RATE_2ms	BIT(3)
+#define LM3692X_RAMP_RATE_4ms	(BIT(3) | BIT(1))
+#define LM3692X_RAMP_RATE_8ms	(BIT(2) | BIT(3))
+#define LM3692X_RAMP_RATE_16ms	(BIT(1) | BIT(2) | BIT(3))
+#define LM3692X_RAMP_EN		BIT(4)
+#define LM3692X_BRHT_MODE_REG	0x00
+#define LM3692X_BRHT_MODE_PWM	BIT(5)
+#define LM3692X_BRHT_MODE_MULTI_RAMP BIT(6)
+#define LM3692X_BRHT_MODE_RAMP_MULTI (BIT(5) | BIT(6))
+#define LM3692X_MAP_MODE_EXP	BIT(7)
+
+/* PWM Register Bits */
+#define LM3692X_PWM_FILTER_100	BIT(0)
+#define LM3692X_PWM_FILTER_150	BIT(1)
+#define LM3692X_PWM_FILTER_200	(BIT(0) | BIT(1))
+#define LM3692X_PWM_HYSTER_1LSB BIT(2)
+#define LM3692X_PWM_HYSTER_2LSB	BIT(3)
+#define LM3692X_PWM_HYSTER_3LSB (BIT(3) | BIT(2))
+#define LM3692X_PWM_HYSTER_4LSB BIT(4)
+#define LM3692X_PWM_HYSTER_5LSB (BIT(4) | BIT(2))
+#define LM3692X_PWM_HYSTER_6LSB (BIT(4) | BIT(3))
+#define LM3692X_PWM_POLARITY	BIT(5)
+#define LM3692X_PWM_SAMP_4MHZ	BIT(6)
+#define LM3692X_PWM_SAMP_24MHZ	BIT(7)
+
+/* Boost Control Bits */
+#define LM3692X_OCP_PROT_1A	BIT(0)
+#define LM3692X_OCP_PROT_1_25A	BIT(1)
+#define LM3692X_OCP_PROT_1_5A	(BIT(0) | BIT(1))
+#define LM3692X_OVP_21V		BIT(2)
+#define LM3692X_OVP_25V		BIT(3)
+#define LM3692X_OVP_29V		(BIT(2) | BIT(3))
+#define LM3692X_MIN_IND_22UH	BIT(4)
+#define LM3692X_BOOST_SW_1MHZ	BIT(5)
+#define LM3692X_BOOST_SW_NO_SHIFT	BIT(6)
+
+/* Fault Control Bits */
+#define LM3692X_FAULT_CTRL_OVP BIT(0)
+#define LM3692X_FAULT_CTRL_OCP BIT(1)
+#define LM3692X_FAULT_CTRL_TSD BIT(2)
+#define LM3692X_FAULT_CTRL_OPEN BIT(3)
+
+/* Fault Flag Bits */
+#define LM3692X_FAULT_FLAG_OVP BIT(0)
+#define LM3692X_FAULT_FLAG_OCP BIT(1)
+#define LM3692X_FAULT_FLAG_TSD BIT(2)
+#define LM3692X_FAULT_FLAG_SHRT BIT(3)
+#define LM3692X_FAULT_FLAG_OPEN BIT(4)
+
+/**
+ * struct lm3692x_led -
+ * @lock - Lock for reading/writing the device
+ * @client - Pointer to the I2C client
+ * @led_dev - LED class device pointer
+ * @regmap - Devices register map
+ * @enable_gpio - VDDIO/EN gpio to enable communication interface
+ * @regulator - LED supply regulator pointer
+ * @label - LED label
+ */
+struct lm3692x_led {
+	struct mutex lock;
+	struct i2c_client *client;
+	struct led_classdev led_dev;
+	struct regmap *regmap;
+	struct gpio_desc *enable_gpio;
+	struct regulator *regulator;
+	char label[LED_MAX_NAME_SIZE];
+};
+
+static const struct reg_default lm3692x_reg_defs[] = {
+	{LM3692X_EN, 0xf},
+	{LM3692X_BRT_CTRL, 0x61},
+	{LM3692X_PWM_CTRL, 0x73},
+	{LM3692X_BOOST_CTRL, 0x6f},
+	{LM3692X_AUTO_FREQ_HI, 0x0},
+	{LM3692X_AUTO_FREQ_LO, 0x0},
+	{LM3692X_BL_ADJ_THRESH, 0x0},
+	{LM3692X_BRT_LSB, 0x7},
+	{LM3692X_BRT_MSB, 0xff},
+	{LM3692X_FAULT_CTRL, 0x7},
+};
+
+static const struct regmap_config lm3692x_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.max_register = LM3692X_FAULT_FLAGS,
+	.reg_defaults = lm3692x_reg_defs,
+	.num_reg_defaults = ARRAY_SIZE(lm3692x_reg_defs),
+	.cache_type = REGCACHE_RBTREE,
+};
+
+static int lm3692x_fault_check(struct lm3692x_led *led)
+{
+	int ret;
+	unsigned int read_buf;
+
+	ret = regmap_read(led->regmap, LM3692X_FAULT_FLAGS, &read_buf);
+	if (ret)
+		return ret;
+
+	if (read_buf)
+		dev_err(&led->client->dev, "Detected a fault 0x%X\n", read_buf);
+
+	/* The first read may clear the fault.  Check again to see if the fault
+	 * still exits and return that value.
+	 */
+	regmap_read(led->regmap, LM3692X_FAULT_FLAGS, &read_buf);
+	if (read_buf)
+		dev_err(&led->client->dev, "Second read of fault flags 0x%X\n",
+			read_buf);
+
+	return read_buf;
+}
+
+static int lm3692x_brightness_set(struct led_classdev *led_cdev,
+				enum led_brightness brt_val)
+{
+	struct lm3692x_led *led =
+			container_of(led_cdev, struct lm3692x_led, led_dev);
+	int ret;
+	int led_brightness_lsb = (brt_val >> 5);
+
+	mutex_lock(&led->lock);
+
+	ret = lm3692x_fault_check(led);
+	if (ret) {
+		dev_err(&led->client->dev, "Cannot read/clear faults\n");
+		goto out;
+	}
+
+	ret = regmap_write(led->regmap, LM3692X_BRT_MSB, brt_val);
+	if (ret) {
+		dev_err(&led->client->dev, "Cannot write MSB\n");
+		goto out;
+	}
+
+	ret = regmap_write(led->regmap, LM3692X_BRT_LSB, led_brightness_lsb);
+	if (ret) {
+		dev_err(&led->client->dev, "Cannot write LSB\n");
+		goto out;
+	}
+out:
+	mutex_unlock(&led->lock);
+	return ret;
+}
+
+static int lm3692x_init(struct lm3692x_led *led)
+{
+	int ret;
+
+	if (led->regulator) {
+		ret = regulator_enable(led->regulator);
+		if (ret) {
+			dev_err(&led->client->dev,
+				"Failed to enable regulator\n");
+			return ret;
+		}
+	}
+
+	if (led->enable_gpio)
+		gpiod_direction_output(led->enable_gpio, 1);
+
+	ret = lm3692x_fault_check(led);
+	if (ret) {
+		dev_err(&led->client->dev, "Cannot read/clear faults\n");
+		goto out;
+	}
+
+	ret = regmap_write(led->regmap, LM3692X_BRT_CTRL, 0x00);
+	if (ret)
+		goto out;
+
+	/*
+	 * For glitch free operation, the following data should
+	 * only be written while device enable bit is 0
+	 * per Section 7.5.14 of the data sheet
+	 */
+	ret = regmap_write(led->regmap, LM3692X_PWM_CTRL,
+		LM3692X_PWM_FILTER_100 | LM3692X_PWM_SAMP_24MHZ);
+	if (ret)
+		goto out;
+
+	ret = regmap_write(led->regmap, LM3692X_BOOST_CTRL,
+			LM3692X_BRHT_MODE_RAMP_MULTI |
+			LM3692X_BL_ADJ_POL |
+			LM3692X_RAMP_RATE_250us);
+	if (ret)
+		goto out;
+
+	ret = regmap_write(led->regmap, LM3692X_AUTO_FREQ_HI, 0x00);
+	if (ret)
+		goto out;
+
+	ret = regmap_write(led->regmap, LM3692X_AUTO_FREQ_LO, 0x00);
+	if (ret)
+		goto out;
+
+	ret = regmap_write(led->regmap, LM3692X_BL_ADJ_THRESH, 0x00);
+	if (ret)
+		goto out;
+
+	ret = regmap_write(led->regmap, LM3692X_BRT_CTRL,
+			LM3692X_BL_ADJ_POL | LM3692X_PWM_HYSTER_4LSB);
+	if (ret)
+		goto out;
+
+	return ret;
+out:
+	dev_err(&led->client->dev, "Fail writing initialization values\n");
+
+	if (led->enable_gpio)
+		gpiod_direction_output(led->enable_gpio, 0);
+
+	if (led->regulator) {
+		ret = regulator_disable(led->regulator);
+		if (ret)
+			dev_err(&led->client->dev,
+				"Failed to disable regulator\n");
+	}
+
+	return ret;
+}
+
+static int lm3692x_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	int ret;
+	struct lm3692x_led *led;
+	struct device_node *np = client->dev.of_node;
+	struct device_node *child_node;
+	const char *name;
+
+	led = devm_kzalloc(&client->dev, sizeof(*led), GFP_KERNEL);
+	if (!led)
+		return -ENOMEM;
+
+	for_each_available_child_of_node(np, child_node) {
+		led->led_dev.default_trigger = of_get_property(child_node,
+						    "linux,default-trigger",
+						    NULL);
+
+		ret = of_property_read_string(child_node, "label", &name);
+		if (!ret)
+		    snprintf(led->label, sizeof(led->label), "%s:%s",
+					np->name, name);
+		else
+		    snprintf(led->label, sizeof(led->label),
+			     "%s::backlight_cluster", id->name);
+	};
+
+	led->enable_gpio = devm_gpiod_get_optional(&client->dev,
+						   "enable", GPIOD_OUT_LOW);
+	if (IS_ERR(led->enable_gpio)) {
+		ret = PTR_ERR(led->enable_gpio);
+		dev_err(&client->dev, "Failed to get enable gpio: %d\n", ret);
+		return ret;
+	}
+
+	led->regulator = devm_regulator_get(&client->dev, "vled");
+	if (IS_ERR(led->regulator))
+		led->regulator = NULL;
+
+	led->client = client;
+	led->led_dev.name = led->label;
+	led->led_dev.brightness_set_blocking = lm3692x_brightness_set;
+
+	mutex_init(&led->lock);
+
+	i2c_set_clientdata(client, led);
+
+	led->regmap = devm_regmap_init_i2c(client, &lm3692x_regmap_config);
+	if (IS_ERR(led->regmap)) {
+		ret = PTR_ERR(led->regmap);
+		dev_err(&client->dev, "Failed to allocate register map: %d\n",
+			ret);
+		return ret;
+	}
+
+	ret = lm3692x_init(led);
+	if (ret)
+		return ret;
+
+	ret = devm_led_classdev_register(&client->dev, &led->led_dev);
+	if (ret) {
+		dev_err(&client->dev, "led register err: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int lm3692x_remove(struct i2c_client *client)
+{
+	struct lm3692x_led *led = i2c_get_clientdata(client);
+	int ret;
+
+	if (led->enable_gpio)
+		gpiod_direction_output(led->enable_gpio, 0);
+
+	if (led->regulator) {
+		ret = regulator_disable(led->regulator);
+		if (ret)
+			dev_err(&led->client->dev,
+				"Failed to disable regulator\n");
+	}
+
+	mutex_destroy(&led->lock);
+
+	return 0;
+}
+
+static const struct i2c_device_id lm3692x_id[] = {
+	{ "lm36922", 0 },
+	{ "lm36923", 1 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, lm3692x_id);
+
+static const struct of_device_id of_lm3692x_leds_match[] = {
+	{ .compatible = "ti,lm36922", },
+	{ .compatible = "ti,lm36923", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_lm3692x_leds_match);
+
+static struct i2c_driver lm3692x_driver = {
+	.driver = {
+		.name	= "lm3692x",
+		.of_match_table = of_lm3692x_leds_match,
+	},
+	.probe		= lm3692x_probe,
+	.remove		= lm3692x_remove,
+	.id_table	= lm3692x_id,
+};
+module_i2c_driver(lm3692x_driver);
+
+MODULE_DESCRIPTION("Texas Instruments LM3692X LED driver");
+MODULE_AUTHOR("Dan Murphy <dmurphy-l0cyMroinI0@public.gmane.org>");
+MODULE_LICENSE("GPL v2");
-- 
2.15.0.124.g7668cbc60

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Re: [PATCH v9 1/2] dt: bindings: lm3692x: Add bindings for lm3692x LED driver

[Jacek Anaszewski]

Dan,

On 12/11/2017 07:26 PM, Dan Murphy wrote:
> This adds the devicetree bindings for the LM3692x
> I2C LED string driver.
> 
> Acked-by: Pavel Machek <pavel-+ZI9xUNit7I@public.gmane.org>
> Signed-off-by: Dan Murphy <dmurphy-l0cyMroinI0@public.gmane.org>
> ---
> 
> v9 - Moved 2 nodes to Optional Child and renamed node names to device type
> https://patchwork.kernel.org/patch/10093757/
> 
> v8 - Added address-cells and size-cells as well as child node reg - https://patchwork.kernel.org/patch/10091259/
> v7 - No changes - https://patchwork.kernel.org/patch/10087475/
> v6 - No changes -https://patchwork.kernel.org/patch/10085567/
> v5 - No Changes - https://patchwork.kernel.org/patch/10081071/
> v4 - Fix example node, added trigger entry, removed ambiguous x for compatible and
> added common.txt pointer for label - https://patchwork.kernel.org/patch/10060107
> v3 - No changes
> v2 - No changes - https://patchwork.kernel.org/patch/10056677/
> 
>  .../devicetree/bindings/leds/leds-lm3692x.txt      | 49 ++++++++++++++++++++++
>  1 file changed, 49 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/leds-lm3692x.txt
> 
> diff --git a/Documentation/devicetree/bindings/leds/leds-lm3692x.txt b/Documentation/devicetree/bindings/leds/leds-lm3692x.txt
> new file mode 100644
> index 000000000000..a93e19edfb42
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/leds-lm3692x.txt
> @@ -0,0 +1,49 @@
> +* Texas Instruments - LM3692x Highly Efficient White LED Driver
> +
> +The LM3692x is an ultra-compact, highly efficient,
> +white-LED driver designed for LCD display backlighting.
> +
> +The main difference between the LM36922 and LM36923 is the number of
> +LED strings it supports.  The LM36922 supports two strings while the LM36923
> +supports three strings.
> +
> +Required properties:
> +	- compatible:
> +		"ti,lm36922"
> +		"ti,lm36923"
> +	- reg :  I2C slave address
> +	- #address-cells : 1
> +	- #size-cells : 0
> +
> +Optional properties:
> +	- enable-gpios : gpio pin to enable/disable the device.
> +	- vled-supply : LED supply
> +
> +Required child properties:
> +	- reg : 0
> +
> +Optional child properties:
> +	- label : see Documentation/devicetree/bindings/leds/common.txt
> +	- linux,default-trigger :
> +	   see Documentation/devicetree/bindings/leds/common.txt
> +
> +Example:
> +
> +led-controller@36 {
> +	compatible = "ti,lm3692x";
> +	reg = <0x36>;
> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +
> +	enable-gpios = <&gpio1 28 GPIO_ACTIVE_HIGH>;
> +	vled-supply = <&vbatt>;
> +
> +	led@0 {
> +		reg = <0>;
> +		label = "backlight_cluster";

We need to consequently adhere to LED class device naming
convention, so:

label = "white:backlight_cluster";

> +		linux,default-trigger = "backlight";
> +	};
> +}
> +
> +For more product information please see the link below:
> +http://www.ti.com/lit/ds/snvsa29/snvsa29.pdf
> 

-- 
Best regards,
Jacek Anaszewski
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