leds: LED driver for National Semiconductor LP3944 Funlight Chip

Kernel driver lp3944

====================

  * National Semiconductor LP3944 Fun-light Chip

    Prefix: 'lp3944'

    Addresses scanned: None (see the Notes section below)

    Datasheet: Publicly available at the National Semiconductor website

               http://www.national.com/pf/LP/LP3944.html

Authors:

        Antonio Ospite <ospite@studenti.unina.it>

Description

-----------

The LP3944 is a helper chip that 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

Setting a led in DIM0 or DIM1 mode makes it blink according to the pattern.

See the datasheet for details.

LP3944 can be found on Motorola A910 smartphone, where it drives the rgb

leds, the camera flash light and the lcds power.

Notes

-----

The chip is used mainly in embedded contexts, so this driver expects it is

registered using the i2c_board_info mechanism.

To register the chip at address 0x60 on adapter 0, set the platform data

according to include/linux/leds-lp3944.h, set the i2c board info:

	static struct i2c_board_info __initdata a910_i2c_board_info[] = {

		{

			I2C_BOARD_INFO("lp3944", 0x60),

			.platform_data = &a910_lp3944_leds,

		},

	};

and register it in the platform init function

	i2c_register_board_info(0, a910_i2c_board_info,

			ARRAY_SIZE(a910_i2c_board_info));

	  of_platform devices.  For instance, LEDs which are listed in a "dts"

	  file.

config LEDS_LP3944

	tristate "LED Support for N.S. LP3944 (Fun Light) I2C chip"

	depends on LEDS_CLASS && I2C

	help

    This option enables support for LEDs connected to the National

    Semiconductor LP3944 Lighting Management Unit (LMU) also known as

    Fun Light Chip.

	  To compile this driver as a module, choose M here: the

	  module will be called leds-lp3944.

config LEDS_CLEVO_MAIL

	tristate "Mail LED on Clevo notebook"

	depends on LEDS_CLASS && X86 && SERIO_I8042 && DMI

obj-$(CONFIG_LEDS_SUNFIRE)		+= leds-sunfire.o

obj-$(CONFIG_LEDS_PCA9532)		+= leds-pca9532.o

obj-$(CONFIG_LEDS_GPIO)			+= leds-gpio.o

obj-$(CONFIG_LEDS_LP3944)		+= leds-lp3944.o

obj-$(CONFIG_LEDS_CLEVO_MAIL)		+= leds-clevo-mail.o

obj-$(CONFIG_LEDS_HP6XX)		+= leds-hp6xx.o

obj-$(CONFIG_LEDS_FSG)			+= leds-fsg.o

/*

 * 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/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;

	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 = kzalloc(sizeof(struct lp3944_data), GFP_KERNEL);

	if (!data)

		return -ENOMEM;

	data->client = client;

	i2c_set_clientdata(client, data);

	mutex_init(&data->lock);

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

	lp3944_configure(client, data, lp3944_pdata);

	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;

		}

	kfree(data);

	i2c_set_clientdata(client, NULL);

	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,

};

static int __init lp3944_module_init(void)

{

	return i2c_add_driver(&lp3944_driver);

}

static void __exit lp3944_module_exit(void)

{

	i2c_del_driver(&lp3944_driver);

}

module_init(lp3944_module_init);

module_exit(lp3944_module_exit);

MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");

MODULE_DESCRIPTION("LP3944 Fun Light Chip");

MODULE_LICENSE("GPL");

/*

 * leds-lp3944.h - platform data structure for lp3944 led controller

 *

 * 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.

 *

 */

#ifndef __LINUX_LEDS_LP3944_H

#define __LINUX_LEDS_LP3944_H

#include <linux/leds.h>

#include <linux/workqueue.h>

#define LP3944_LED0 0

#define LP3944_LED1 1

#define LP3944_LED2 2

#define LP3944_LED3 3

#define LP3944_LED4 4

#define LP3944_LED5 5

#define LP3944_LED6 6

#define LP3944_LED7 7

#define LP3944_LEDS_MAX 8

#define LP3944_LED_STATUS_MASK	0x03

enum lp3944_status {

	LP3944_LED_STATUS_OFF  = 0x0,

	LP3944_LED_STATUS_ON   = 0x1,

	LP3944_LED_STATUS_DIM0 = 0x2,

	LP3944_LED_STATUS_DIM1 = 0x3

};

enum lp3944_type {

	LP3944_LED_TYPE_NONE,

	LP3944_LED_TYPE_LED,

	LP3944_LED_TYPE_LED_INVERTED,

};

struct lp3944_led {

	char *name;

	enum lp3944_type type;

	enum lp3944_status status;

};

struct lp3944_platform_data {

	struct lp3944_led leds[LP3944_LEDS_MAX];

	u8 leds_size;

};

#endif /* __LINUX_LEDS_LP3944_H */