Date:   Fri, 1 Dec 2017 10:34:36 -0600
From:   Dan Murphy <dmurphy@...com>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>, <rpurdie@...ys.net>,
        <pavel@....cz>
CC:     <linux-leds@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 2/2] leds: lm3692x: Introduce LM3692x dual string
 driver

Jacek

On 11/30/2017 03:38 PM, Jacek Anaszewski wrote:
> Dan,
> 
> Thanks for addressing my remarks. LED class device name
> composition stills needs some tweaking, though.
> 
> Please refer below to the piece of code in question.
> 
> On 11/30/2017 08:22 PM, Dan Murphy wrote:
>> 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@...com>
>> ---
>> 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 | 396 ++++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 404 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..70c974e06bd7
>> --- /dev/null
>> +++ b/drivers/leds/leds-lm3692x.c
>> @@ -0,0 +1,396 @@
>> +/*
>> + * TI lm3692x LED Driver
>> + *
>> + * Copyright (C) 2017 Texas Instruments
>> + *
>> + * Author: Dan Murphy <dmurphy@...com>
>> + *
>> + * 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>
>> +
>> +#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[32];
>> +};
>> +
>> +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;
>> +	char trigger[32] = ":none";
>> +
>> +	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);
>> +
>> +		if (led->led_dev.default_trigger)
>> +			snprintf(trigger, sizeof(trigger), ":%s",
>> +				led->led_dev.default_trigger);
> 
> Let's not use trigger name for the LED function name. Trigger cannot
> define LED function, since LED class device can be assigned any
> other trigger at any time. Please drop above "if" statement.
> 
>> +
>> +		ret = of_property_read_string(child_node, "label", &name);
>> +		if (!ret)
>> +			strlcpy(led->label, name, sizeof(led->label));
>> +		else
>> +			snprintf(led->label, sizeof(led->label), "%s:white%s",
>> +				np->name, trigger);
> 
> You'll need to change label in your DT bindings example to:
> 
> label = "white:backlight_cluster"
> 
> and after that the LED class device name should be constructed like
> below. Sorry for not being precise enough.
> 
> 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:white:backlight_cluster",
> 			np->name)
> 
> You could even make this a generic LED core function e.g.
> 
> void of_led_compose_name(struct device_node *parent,
>                          struct device_node *child)
> 

New LED class API coming your way in v6 along with some other driver changes for examples

Dan

> It's up to you, I'm going to do that anyway when I'll find a moment.
> 
>> +	};
>> +
>> +	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@...com>");
>> +MODULE_LICENSE("GPL v2");
>>
> 


-- 
------------------
Dan Murphy

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