drivers/leds/leds-lp3944.c - kernel/msm-4.9 - Gitiles

 /*
  * leds-lp3944.c - driver for National Semiconductor LP3944 Funlight Chip
  *
  * Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
  *
  * 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.
  *
  */

 /*
  * I2C driver for National Semiconductor LP3944 Funlight Chip
  * http://www.national.com/pf/LP/LP3944.html
  *
  * This helper chip can drive up to 8 leds, with two programmable DIM modes;
  * it could even be used as a gpio expander but this driver assumes it is used
  * as a led controller.
  *
  * The DIM modes are used to set _blink_ patterns for leds, the pattern is
  * specified supplying two parameters:
  *   - period: from 0s to 1.6s
  *   - duty cycle: percentage of the period the led is on, from 0 to 100
  *
  * LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
  * leds, the camera flash light and the displays backlights.
  */

 #include <linux/module.h>
 #include <linux/i2c.h>
 #include <linux/slab.h>
 #include <linux/leds.h>
 #include <linux/mutex.h>
 #include <linux/workqueue.h>
 #include <linux/leds-lp3944.h>

 /* Read Only Registers */
 #define LP3944_REG_INPUT1     0x00 /* LEDs 0-7 InputRegister (Read Only) */
 #define LP3944_REG_REGISTER1  0x01 /* None (Read Only) */

 #define LP3944_REG_PSC0       0x02 /* Frequency Prescaler 0 (R/W) */
 #define LP3944_REG_PWM0       0x03 /* PWM Register 0 (R/W) */
 #define LP3944_REG_PSC1       0x04 /* Frequency Prescaler 1 (R/W) */
 #define LP3944_REG_PWM1       0x05 /* PWM Register 1 (R/W) */
 #define LP3944_REG_LS0        0x06 /* LEDs 0-3 Selector (R/W) */
 #define LP3944_REG_LS1        0x07 /* LEDs 4-7 Selector (R/W) */

 /* These registers are not used to control leds in LP3944, they can store
  * arbitrary values which the chip will ignore.
  */
 #define LP3944_REG_REGISTER8  0x08
 #define LP3944_REG_REGISTER9  0x09

 #define LP3944_DIM0 0
 #define LP3944_DIM1 1

 /* period in ms */
 #define LP3944_PERIOD_MIN 0
 #define LP3944_PERIOD_MAX 1600

 /* duty cycle is a percentage */
 #define LP3944_DUTY_CYCLE_MIN 0
 #define LP3944_DUTY_CYCLE_MAX 100

 #define ldev_to_led(c)       container_of(c, struct lp3944_led_data, ldev)

 /* Saved data */
 struct lp3944_led_data {
 	u8 id;
 	enum lp3944_type type;
 	enum lp3944_status status;
 	struct led_classdev ldev;
 	struct i2c_client *client;
 	struct work_struct work;
 };

 struct lp3944_data {
 	struct mutex lock;
 	struct i2c_client *client;
 	struct lp3944_led_data leds[LP3944_LEDS_MAX];
 };

 static int lp3944_reg_read(struct i2c_client *client, u8 reg, u8 *value)
 {
 	int tmp;

 	tmp = i2c_smbus_read_byte_data(client, reg);
 	if (tmp < 0)
 		return -EINVAL;

 	*value = tmp;

 	return 0;
 }

 static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value)
 {
 	return i2c_smbus_write_byte_data(client, reg, value);
 }

 /**
  * Set the period for DIM status
  *
  * @client: the i2c client
  * @dim: either LP3944_DIM0 or LP3944_DIM1
  * @period: period of a blink, that is a on/off cycle, expressed in ms.
  */
 static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period)
 {
 	u8 psc_reg;
 	u8 psc_value;
 	int err;

 	if (dim == LP3944_DIM0)
 		psc_reg = LP3944_REG_PSC0;
 	else if (dim == LP3944_DIM1)
 		psc_reg = LP3944_REG_PSC1;
 	else
 		return -EINVAL;

 	/* Convert period to Prescaler value */
 	if (period > LP3944_PERIOD_MAX)
 		return -EINVAL;

 	psc_value = (period * 255) / LP3944_PERIOD_MAX;

 	err = lp3944_reg_write(client, psc_reg, psc_value);

 	return err;
 }

 /**
  * Set the duty cycle for DIM status
  *
  * @client: the i2c client
  * @dim: either LP3944_DIM0 or LP3944_DIM1
  * @duty_cycle: percentage of a period during which a led is ON
  */
 static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim,
 				    u8 duty_cycle)
 {
 	u8 pwm_reg;
 	u8 pwm_value;
 	int err;

 	if (dim == LP3944_DIM0)
 		pwm_reg = LP3944_REG_PWM0;
 	else if (dim == LP3944_DIM1)
 		pwm_reg = LP3944_REG_PWM1;
 	else
 		return -EINVAL;

 	/* Convert duty cycle to PWM value */
 	if (duty_cycle > LP3944_DUTY_CYCLE_MAX)
 		return -EINVAL;

 	pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX;

 	err = lp3944_reg_write(client, pwm_reg, pwm_value);

 	return err;
 }

 /**
  * Set the led status
  *
  * @led: a lp3944_led_data structure
  * @status: one of LP3944_LED_STATUS_OFF
  *                 LP3944_LED_STATUS_ON
  *                 LP3944_LED_STATUS_DIM0
  *                 LP3944_LED_STATUS_DIM1
  */
 static int lp3944_led_set(struct lp3944_led_data *led, u8 status)
 {
 	struct lp3944_data *data = i2c_get_clientdata(led->client);
 	u8 id = led->id;
 	u8 reg;
 	u8 val = 0;
 	int err;

 	dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n",
 		__func__, led->ldev.name, status);

 	switch (id) {
 	case LP3944_LED0:
 	case LP3944_LED1:
 	case LP3944_LED2:
 	case LP3944_LED3:
 		reg = LP3944_REG_LS0;
 		break;
 	case LP3944_LED4:
 	case LP3944_LED5:
 	case LP3944_LED6:
 	case LP3944_LED7:
 		id -= LP3944_LED4;
 		reg = LP3944_REG_LS1;
 		break;
 	default:
 		return -EINVAL;
 	}

 	if (status > LP3944_LED_STATUS_DIM1)
 		return -EINVAL;

 	/* invert only 0 and 1, leave unchanged the other values,
 	 * remember we are abusing status to set blink patterns
 	 */
 	if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2)
 		status = 1 - status;

 	mutex_lock(&data->lock);
 	lp3944_reg_read(led->client, reg, &val);

 	val &= ~(LP3944_LED_STATUS_MASK << (id << 1));
 	val |= (status << (id << 1));

 	dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n",
 		__func__, led->ldev.name, reg, id, status, val);

 	/* set led status */
 	err = lp3944_reg_write(led->client, reg, val);
 	mutex_unlock(&data->lock);

 	return err;
 }

 static int lp3944_led_set_blink(struct led_classdev *led_cdev,
 				unsigned long *delay_on,
 				unsigned long *delay_off)
 {
 	struct lp3944_led_data *led = ldev_to_led(led_cdev);
 	u16 period;
 	u8 duty_cycle;
 	int err;

 	/* units are in ms */
 	if (*delay_on + *delay_off > LP3944_PERIOD_MAX)
 		return -EINVAL;

 	if (*delay_on == 0 && *delay_off == 0) {
 		/* Special case: the leds subsystem requires a default user
 		 * friendly blink pattern for the LED.  Let's blink the led
 		 * slowly (1Hz).
 		 */
 		*delay_on = 500;
 		*delay_off = 500;
 	}

 	period = (*delay_on) + (*delay_off);

 	/* duty_cycle is the percentage of period during which the led is ON */
 	duty_cycle = 100 * (*delay_on) / period;

 	/* invert duty cycle for inverted leds, this has the same effect of
 	 * swapping delay_on and delay_off
 	 */
 	if (led->type == LP3944_LED_TYPE_LED_INVERTED)
 		duty_cycle = 100 - duty_cycle;

 	/* NOTE: using always the first DIM mode, this means that all leds
 	 * will have the same blinking pattern.
 	 *
 	 * We could find a way later to have two leds blinking in hardware
 	 * with different patterns at the same time, falling back to software
 	 * control for the other ones.
 	 */
 	err = lp3944_dim_set_period(led->client, LP3944_DIM0, period);
 	if (err)
 		return err;

 	err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle);
 	if (err)
 		return err;

 	dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n",
 		__func__);

 	led->status = LP3944_LED_STATUS_DIM0;
 	schedule_work(&led->work);

 	return 0;
 }

 static void lp3944_led_set_brightness(struct led_classdev *led_cdev,
 				      enum led_brightness brightness)
 {
 	struct lp3944_led_data *led = ldev_to_led(led_cdev);

 	dev_dbg(&led->client->dev, "%s: %s, %d\n",
 		__func__, led_cdev->name, brightness);

 	led->status = brightness;
 	schedule_work(&led->work);
 }

 static void lp3944_led_work(struct work_struct *work)
 {
 	struct lp3944_led_data *led;

 	led = container_of(work, struct lp3944_led_data, work);
 	lp3944_led_set(led, led->status);
 }

 static int lp3944_configure(struct i2c_client *client,
 			    struct lp3944_data *data,
 			    struct lp3944_platform_data *pdata)
 {
 	int i, err = 0;

 	for (i = 0; i < pdata->leds_size; i++) {
 		struct lp3944_led *pled = &pdata->leds[i];
 		struct lp3944_led_data *led = &data->leds[i];
 		led->client = client;
 		led->id = i;

 		switch (pled->type) {

 		case LP3944_LED_TYPE_LED:
 		case LP3944_LED_TYPE_LED_INVERTED:
 			led->type = pled->type;
 			led->status = pled->status;
 			led->ldev.name = pled->name;
 			led->ldev.max_brightness = 1;
 			led->ldev.brightness_set = lp3944_led_set_brightness;
 			led->ldev.blink_set = lp3944_led_set_blink;
 			led->ldev.flags = LED_CORE_SUSPENDRESUME;

 			INIT_WORK(&led->work, lp3944_led_work);
 			err = led_classdev_register(&client->dev, &led->ldev);
 			if (err < 0) {
 				dev_err(&client->dev,
 					"couldn't register LED %s\n",
 					led->ldev.name);
 				goto exit;
 			}

 			/* to expose the default value to userspace */
 			led->ldev.brightness = led->status;

 			/* Set the default led status */
 			err = lp3944_led_set(led, led->status);
 			if (err < 0) {
 				dev_err(&client->dev,
 					"%s couldn't set STATUS %d\n",
 					led->ldev.name, led->status);
 				goto exit;
 			}
 			break;

 		case LP3944_LED_TYPE_NONE:
 		default:
 			break;

 		}
 	}
 	return 0;

 exit:
 	if (i > 0)
 		for (i = i - 1; i >= 0; i--)
 			switch (pdata->leds[i].type) {

 			case LP3944_LED_TYPE_LED:
 			case LP3944_LED_TYPE_LED_INVERTED:
 				led_classdev_unregister(&data->leds[i].ldev);
 				cancel_work_sync(&data->leds[i].work);
 				break;

 			case LP3944_LED_TYPE_NONE:
 			default:
 				break;
 			}

 	return err;
 }

 static int __devinit lp3944_probe(struct i2c_client *client,
 				  const struct i2c_device_id *id)
 {
 	struct lp3944_platform_data *lp3944_pdata = client->dev.platform_data;
 	struct lp3944_data *data;
 	int err;

 	if (lp3944_pdata == NULL) {
 		dev_err(&client->dev, "no platform data\n");
 		return -EINVAL;
 	}

 	/* Let's see whether this adapter can support what we need. */
 	if (!i2c_check_functionality(client->adapter,
 				I2C_FUNC_SMBUS_BYTE_DATA)) {
 		dev_err(&client->dev, "insufficient functionality!\n");
 		return -ENODEV;
 	}

 	data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data),
 			GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	data->client = client;
 	i2c_set_clientdata(client, data);

 	mutex_init(&data->lock);

 	err = lp3944_configure(client, data, lp3944_pdata);
 	if (err < 0)
 		return err;

 	dev_info(&client->dev, "lp3944 enabled\n");
 	return 0;
 }

 static int __devexit lp3944_remove(struct i2c_client *client)
 {
 	struct lp3944_platform_data *pdata = client->dev.platform_data;
 	struct lp3944_data *data = i2c_get_clientdata(client);
 	int i;

 	for (i = 0; i < pdata->leds_size; i++)
 		switch (data->leds[i].type) {
 		case LP3944_LED_TYPE_LED:
 		case LP3944_LED_TYPE_LED_INVERTED:
 			led_classdev_unregister(&data->leds[i].ldev);
 			cancel_work_sync(&data->leds[i].work);
 			break;

 		case LP3944_LED_TYPE_NONE:
 		default:
 			break;
 		}

 	return 0;
 }

 /* lp3944 i2c driver struct */
 static const struct i2c_device_id lp3944_id[] = {
 	{"lp3944", 0},
 	{}
 };

 MODULE_DEVICE_TABLE(i2c, lp3944_id);

 static struct i2c_driver lp3944_driver = {
 	.driver   = {
 		   .name = "lp3944",
 	},
 	.probe    = lp3944_probe,
 	.remove   = __devexit_p(lp3944_remove),
 	.id_table = lp3944_id,
 };

 module_i2c_driver(lp3944_driver);

 MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
 MODULE_DESCRIPTION("LP3944 Fun Light Chip");
 MODULE_LICENSE("GPL");
	/*
	* leds-lp3944.c - driver for National Semiconductor LP3944 Funlight Chip
	*
	* Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
	*
	* 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.
	*
	*/

	/*
	* I2C driver for National Semiconductor LP3944 Funlight Chip
	* http://www.national.com/pf/LP/LP3944.html
	*
	* This helper chip can drive up to 8 leds, with two programmable DIM modes;
	* it could even be used as a gpio expander but this driver assumes it is used
	* as a led controller.
	*
	* The DIM modes are used to set _blink_ patterns for leds, the pattern is
	* specified supplying two parameters:
	* - period: from 0s to 1.6s
	* - duty cycle: percentage of the period the led is on, from 0 to 100
	*
	* LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
	* leds, the camera flash light and the displays backlights.
	*/

	#include <linux/module.h>
	#include <linux/i2c.h>
	#include <linux/slab.h>
	#include <linux/leds.h>
	#include <linux/mutex.h>
	#include <linux/workqueue.h>
	#include <linux/leds-lp3944.h>

	/* Read Only Registers */
	#define LP3944_REG_INPUT1 0x00 /* LEDs 0-7 InputRegister (Read Only) */
	#define LP3944_REG_REGISTER1 0x01 /* None (Read Only) */

	#define LP3944_REG_PSC0 0x02 /* Frequency Prescaler 0 (R/W) */
	#define LP3944_REG_PWM0 0x03 /* PWM Register 0 (R/W) */
	#define LP3944_REG_PSC1 0x04 /* Frequency Prescaler 1 (R/W) */
	#define LP3944_REG_PWM1 0x05 /* PWM Register 1 (R/W) */
	#define LP3944_REG_LS0 0x06 /* LEDs 0-3 Selector (R/W) */
	#define LP3944_REG_LS1 0x07 /* LEDs 4-7 Selector (R/W) */

	/* These registers are not used to control leds in LP3944, they can store
	* arbitrary values which the chip will ignore.
	*/
	#define LP3944_REG_REGISTER8 0x08
	#define LP3944_REG_REGISTER9 0x09

	#define LP3944_DIM0 0
	#define LP3944_DIM1 1

	/* period in ms */
	#define LP3944_PERIOD_MIN 0
	#define LP3944_PERIOD_MAX 1600

	/* duty cycle is a percentage */
	#define LP3944_DUTY_CYCLE_MIN 0
	#define LP3944_DUTY_CYCLE_MAX 100

	#define ldev_to_led(c) container_of(c, struct lp3944_led_data, ldev)

	/* Saved data */
	struct lp3944_led_data {
	u8 id;
	enum lp3944_type type;
	enum lp3944_status status;
	struct led_classdev ldev;
	struct i2c_client *client;
	struct work_struct work;
	};

	struct lp3944_data {
	struct mutex lock;
	struct i2c_client *client;
	struct lp3944_led_data leds[LP3944_LEDS_MAX];
	};

	static int lp3944_reg_read(struct i2c_client client, u8 reg, u8 value)
	{
	int tmp;

	tmp = i2c_smbus_read_byte_data(client, reg);
	if (tmp < 0)
	return -EINVAL;

	*value = tmp;

	return 0;
	}

	static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value)
	{
	return i2c_smbus_write_byte_data(client, reg, value);
	}

	/**
	* Set the period for DIM status
	*
	* @client: the i2c client
	* @dim: either LP3944_DIM0 or LP3944_DIM1
	* @period: period of a blink, that is a on/off cycle, expressed in ms.
	*/
	static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period)
	{
	u8 psc_reg;
	u8 psc_value;
	int err;

	if (dim == LP3944_DIM0)
	psc_reg = LP3944_REG_PSC0;
	else if (dim == LP3944_DIM1)
	psc_reg = LP3944_REG_PSC1;
	else
	return -EINVAL;

	/* Convert period to Prescaler value */
	if (period > LP3944_PERIOD_MAX)
	return -EINVAL;

	psc_value = (period * 255) / LP3944_PERIOD_MAX;

	err = lp3944_reg_write(client, psc_reg, psc_value);

	return err;
	}

	/**
	* Set the duty cycle for DIM status
	*
	* @client: the i2c client
	* @dim: either LP3944_DIM0 or LP3944_DIM1
	* @duty_cycle: percentage of a period during which a led is ON
	*/
	static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim,
	u8 duty_cycle)
	{
	u8 pwm_reg;
	u8 pwm_value;
	int err;

	if (dim == LP3944_DIM0)
	pwm_reg = LP3944_REG_PWM0;
	else if (dim == LP3944_DIM1)
	pwm_reg = LP3944_REG_PWM1;
	else
	return -EINVAL;

	/* Convert duty cycle to PWM value */
	if (duty_cycle > LP3944_DUTY_CYCLE_MAX)
	return -EINVAL;

	pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX;

	err = lp3944_reg_write(client, pwm_reg, pwm_value);

	return err;
	}

	/**
	* Set the led status
	*
	* @led: a lp3944_led_data structure
	* @status: one of LP3944_LED_STATUS_OFF
	* LP3944_LED_STATUS_ON
	* LP3944_LED_STATUS_DIM0
	* LP3944_LED_STATUS_DIM1
	*/
	static int lp3944_led_set(struct lp3944_led_data *led, u8 status)
	{
	struct lp3944_data *data = i2c_get_clientdata(led->client);
	u8 id = led->id;
	u8 reg;
	u8 val = 0;
	int err;

	dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n",
	__func__, led->ldev.name, status);

	switch (id) {
	case LP3944_LED0:
	case LP3944_LED1:
	case LP3944_LED2:
	case LP3944_LED3:
	reg = LP3944_REG_LS0;
	break;
	case LP3944_LED4:
	case LP3944_LED5:
	case LP3944_LED6:
	case LP3944_LED7:
	id -= LP3944_LED4;
	reg = LP3944_REG_LS1;
	break;
	default:
	return -EINVAL;
	}

	if (status > LP3944_LED_STATUS_DIM1)
	return -EINVAL;

	/* invert only 0 and 1, leave unchanged the other values,
	* remember we are abusing status to set blink patterns
	*/
	if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2)
	status = 1 - status;

	mutex_lock(&data->lock);
	lp3944_reg_read(led->client, reg, &val);

	val &= ~(LP3944_LED_STATUS_MASK << (id << 1));
	val \|= (status << (id << 1));

	dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n",
	__func__, led->ldev.name, reg, id, status, val);

	/* set led status */
	err = lp3944_reg_write(led->client, reg, val);
	mutex_unlock(&data->lock);

	return err;
	}

	static int lp3944_led_set_blink(struct led_classdev *led_cdev,
	unsigned long *delay_on,
	unsigned long *delay_off)
	{
	struct lp3944_led_data *led = ldev_to_led(led_cdev);
	u16 period;
	u8 duty_cycle;
	int err;

	/* units are in ms */
	if (delay_on + delay_off > LP3944_PERIOD_MAX)
	return -EINVAL;

	if (delay_on == 0 && delay_off == 0) {
	/* Special case: the leds subsystem requires a default user
	* friendly blink pattern for the LED. Let's blink the led
	* slowly (1Hz).
	*/
	*delay_on = 500;
	*delay_off = 500;
	}

	period = (delay_on) + (delay_off);

	/* duty_cycle is the percentage of period during which the led is ON */
	duty_cycle = 100 * (*delay_on) / period;

	/* invert duty cycle for inverted leds, this has the same effect of
	* swapping delay_on and delay_off
	*/
	if (led->type == LP3944_LED_TYPE_LED_INVERTED)
	duty_cycle = 100 - duty_cycle;

	/* NOTE: using always the first DIM mode, this means that all leds
	* will have the same blinking pattern.
	*
	* We could find a way later to have two leds blinking in hardware
	* with different patterns at the same time, falling back to software
	* control for the other ones.
	*/
	err = lp3944_dim_set_period(led->client, LP3944_DIM0, period);
	if (err)
	return err;

	err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle);
	if (err)
	return err;

	dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n",
	__func__);

	led->status = LP3944_LED_STATUS_DIM0;
	schedule_work(&led->work);

	return 0;
	}

	static void lp3944_led_set_brightness(struct led_classdev *led_cdev,
	enum led_brightness brightness)
	{
	struct lp3944_led_data *led = ldev_to_led(led_cdev);

	dev_dbg(&led->client->dev, "%s: %s, %d\n",
	__func__, led_cdev->name, brightness);

	led->status = brightness;
	schedule_work(&led->work);
	}

	static void lp3944_led_work(struct work_struct *work)
	{
	struct lp3944_led_data *led;

	led = container_of(work, struct lp3944_led_data, work);
	lp3944_led_set(led, led->status);
	}

	static int lp3944_configure(struct i2c_client *client,
	struct lp3944_data *data,
	struct lp3944_platform_data *pdata)
	{
	int i, err = 0;

	for (i = 0; i < pdata->leds_size; i++) {
	struct lp3944_led *pled = &pdata->leds[i];
	struct lp3944_led_data *led = &data->leds[i];
	led->client = client;
	led->id = i;

	switch (pled->type) {

	case LP3944_LED_TYPE_LED:
	case LP3944_LED_TYPE_LED_INVERTED:
	led->type = pled->type;
	led->status = pled->status;
	led->ldev.name = pled->name;
	led->ldev.max_brightness = 1;
	led->ldev.brightness_set = lp3944_led_set_brightness;
	led->ldev.blink_set = lp3944_led_set_blink;
	led->ldev.flags = LED_CORE_SUSPENDRESUME;

	INIT_WORK(&led->work, lp3944_led_work);
	err = led_classdev_register(&client->dev, &led->ldev);
	if (err < 0) {
	dev_err(&client->dev,
	"couldn't register LED %s\n",
	led->ldev.name);
	goto exit;
	}

	/* to expose the default value to userspace */
	led->ldev.brightness = led->status;

	/* Set the default led status */
	err = lp3944_led_set(led, led->status);
	if (err < 0) {
	dev_err(&client->dev,
	"%s couldn't set STATUS %d\n",
	led->ldev.name, led->status);
	goto exit;
	}
	break;

	case LP3944_LED_TYPE_NONE:
	default:
	break;

	}
	}
	return 0;

	exit:
	if (i > 0)
	for (i = i - 1; i >= 0; i--)
	switch (pdata->leds[i].type) {

	case LP3944_LED_TYPE_LED:
	case LP3944_LED_TYPE_LED_INVERTED:
	led_classdev_unregister(&data->leds[i].ldev);
	cancel_work_sync(&data->leds[i].work);
	break;

	case LP3944_LED_TYPE_NONE:
	default:
	break;
	}

	return err;
	}

	static int __devinit lp3944_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct lp3944_platform_data *lp3944_pdata = client->dev.platform_data;
	struct lp3944_data *data;
	int err;

	if (lp3944_pdata == NULL) {
	dev_err(&client->dev, "no platform data\n");
	return -EINVAL;
	}

	/* Let's see whether this adapter can support what we need. */
	if (!i2c_check_functionality(client->adapter,
	I2C_FUNC_SMBUS_BYTE_DATA)) {
	dev_err(&client->dev, "insufficient functionality!\n");
	return -ENODEV;
	}

	data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data),
	GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	data->client = client;
	i2c_set_clientdata(client, data);

	mutex_init(&data->lock);

	err = lp3944_configure(client, data, lp3944_pdata);
	if (err < 0)
	return err;

	dev_info(&client->dev, "lp3944 enabled\n");
	return 0;
	}

	static int __devexit lp3944_remove(struct i2c_client *client)
	{
	struct lp3944_platform_data *pdata = client->dev.platform_data;
	struct lp3944_data *data = i2c_get_clientdata(client);
	int i;

	for (i = 0; i < pdata->leds_size; i++)
	switch (data->leds[i].type) {
	case LP3944_LED_TYPE_LED:
	case LP3944_LED_TYPE_LED_INVERTED:
	led_classdev_unregister(&data->leds[i].ldev);
	cancel_work_sync(&data->leds[i].work);
	break;

	case LP3944_LED_TYPE_NONE:
	default:
	break;
	}

	return 0;
	}

	/* lp3944 i2c driver struct */
	static const struct i2c_device_id lp3944_id[] = {
	{"lp3944", 0},
	{}
	};

	MODULE_DEVICE_TABLE(i2c, lp3944_id);

	static struct i2c_driver lp3944_driver = {
	.driver = {
	.name = "lp3944",
	},
	.probe = lp3944_probe,
	.remove = __devexit_p(lp3944_remove),
	.id_table = lp3944_id,
	};

	module_i2c_driver(lp3944_driver);

	MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
	MODULE_DESCRIPTION("LP3944 Fun Light Chip");
	MODULE_LICENSE("GPL");