Date:   Wed, 29 Nov 2017 22:52:17 +0100
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Dan Murphy <dmurphy@...com>, rpurdie@...ys.net, pavel@....cz
Cc:     linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/2] leds: lm3692x: Introduce LM3692x dual string
 driver

Hi Dan,

Thanks for the update.

On 11/28/2017 09:40 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>
> ---
> 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 | 382 ++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 390 insertions(+)
>  create mode 100644 drivers/leds/leds-lm3692x.c
> 
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 318a28fd58fe..c0583f1bc8ea 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
> +	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..fcf0573fb985
> --- /dev/null
> +++ b/drivers/leds/leds-lm3692x.c
> @@ -0,0 +1,382 @@
> +/*
> + * 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

s/led class/LED class/

> + * @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;
> +	const char *label;
> +};
> +
> +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);
> +
> +	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;
> +
> +	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.name = of_get_property(child_node, "label", NULL) ? :
> +						 child_node->name;

You need also devicename segment in the LED class device name.
You can take it from the parent node name. Please follow what has been
done for drivers/leds/leds-as3645a.c, with a reservation that your
DT binding is correct, as it doesn't contain devicename segment,
which turned out to be against DT specification. So you'll need
to tweak a bit leds-as3645a.c way of composing LED class device
name to take devicename from parent DT node also for the case
when DT label property is present.

I will be convenient to create some generic LED core function
for composing LED class device name basing on DT data.

All these findings are quite recent, that's why there is no
well established approach to the problem.

> +
> +		led->led_dev.default_trigger = of_get_property(child_node,
> +						    "linux,default-trigger",
> +						    NULL);
> +	};
> +
> +	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.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;
> +
> +	led_classdev_unregister(&led->led_dev);

You don't need it if registering with devm* API.

> +
> +	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);
> +
> +#ifdef CONFIG_OF

We seem to entirely rely on OF.
Let's drop this guard and add OF dependency to Kconfig.

> +static const struct of_device_id of_lm3692x_leds_match[] = {
> +	{ .compatible = "ti,lm36922", },
> +	{ .compatible = "ti,lm36923", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, of_lm3692x_leds_match);
> +#endif
> +
> +static struct i2c_driver lm3692x_driver = {
> +	.driver = {
> +		.name	= "lm3692x",
> +		.of_match_table = of_match_ptr(of_lm3692x_leds_match),

Also of_match_ptr() will be redundant then.

> +	},
> +	.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");
> 

-- 
Best regards,
Jacek Anaszewski

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