/*
   * 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 tmp;
  
  	*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
  ",
  		__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
  ",
  		__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!
  ",
  		__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
  ",
  		__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
  ",
  					led->ldev.name);
  				goto exit;
  			}
  
  			/* to expose the default value to userspace */
  			led->ldev.brightness =
  					(enum led_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
  ",
  					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 lp3944_probe(struct i2c_client *client,
  				  const struct i2c_device_id *id)
  {
  	struct lp3944_platform_data *lp3944_pdata =
  			dev_get_platdata(&client->dev);
  	struct lp3944_data *data;
  	int err;
  
  	if (lp3944_pdata == NULL) {
  		dev_err(&client->dev, "no platform data
  ");
  		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!
  ");
  		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
  ");
  	return 0;
  }
  
  static int lp3944_remove(struct i2c_client *client)
  {
  	struct lp3944_platform_data *pdata = dev_get_platdata(&client->dev);
  	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   = 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");