/*
   * Voltage and current regulation for AD5398 and AD5821
   *
   * Copyright 2010 Analog Devices Inc.
   *
   * Enter bugs at http://blackfin.uclinux.org/
   *
   * Licensed under the GPL-2 or later.
   */
  
  #include <linux/module.h>
  #include <linux/err.h>
  #include <linux/i2c.h>
  #include <linux/slab.h>
  #include <linux/platform_device.h>
  #include <linux/regulator/driver.h>
  #include <linux/regulator/machine.h>
  
  #define AD5398_CURRENT_EN_MASK	0x8000
  
  struct ad5398_chip_info {
  	struct i2c_client *client;
  	int min_uA;
  	int max_uA;
  	unsigned int current_level;
  	unsigned int current_mask;
  	unsigned int current_offset;
  	struct regulator_dev *rdev;
  };
  
  static int ad5398_calc_current(struct ad5398_chip_info *chip,
  	unsigned selector)
  {
  	unsigned range_uA = chip->max_uA - chip->min_uA;
  
  	return chip->min_uA + (selector * range_uA / chip->current_level);
  }
  
  static int ad5398_read_reg(struct i2c_client *client, unsigned short *data)
  {
  	unsigned short val;
  	int ret;
  
  	ret = i2c_master_recv(client, (char *)&val, 2);
  	if (ret < 0) {
  		dev_err(&client->dev, "I2C read error
  ");
  		return ret;
  	}
  	*data = be16_to_cpu(val);
  
  	return ret;
  }
  
  static int ad5398_write_reg(struct i2c_client *client, const unsigned short data)
  {
  	unsigned short val;
  	int ret;
  
  	val = cpu_to_be16(data);
  	ret = i2c_master_send(client, (char *)&val, 2);
  	if (ret < 0)
  		dev_err(&client->dev, "I2C write error
  ");
  
  	return ret;
  }
  
  static int ad5398_get_current_limit(struct regulator_dev *rdev)
  {
  	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
  	struct i2c_client *client = chip->client;
  	unsigned short data;
  	int ret;
  
  	ret = ad5398_read_reg(client, &data);
  	if (ret < 0)
  		return ret;
  
  	ret = (data & chip->current_mask) >> chip->current_offset;
  
  	return ad5398_calc_current(chip, ret);
  }
  
  static int ad5398_set_current_limit(struct regulator_dev *rdev, int min_uA, int max_uA)
  {
  	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
  	struct i2c_client *client = chip->client;
  	unsigned range_uA = chip->max_uA - chip->min_uA;
  	unsigned selector;
  	unsigned short data;
  	int ret;
  
  	if (min_uA < chip->min_uA)
  		min_uA = chip->min_uA;
  	if (max_uA > chip->max_uA)
  		max_uA = chip->max_uA;
  
  	if (min_uA > chip->max_uA || max_uA < chip->min_uA)
  		return -EINVAL;
  
  	selector = DIV_ROUND_UP((min_uA - chip->min_uA) * chip->current_level,
  				range_uA);
  	if (ad5398_calc_current(chip, selector) > max_uA)
  		return -EINVAL;
  
  	dev_dbg(&client->dev, "changing current %duA
  ",
  		ad5398_calc_current(chip, selector));
  
  	/* read chip enable bit */
  	ret = ad5398_read_reg(client, &data);
  	if (ret < 0)
  		return ret;
  
  	/* prepare register data */
  	selector = (selector << chip->current_offset) & chip->current_mask;
  	data = (unsigned short)selector | (data & AD5398_CURRENT_EN_MASK);
  
  	/* write the new current value back as well as enable bit */
  	ret = ad5398_write_reg(client, data);
  
  	return ret;
  }
  
  static int ad5398_is_enabled(struct regulator_dev *rdev)
  {
  	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
  	struct i2c_client *client = chip->client;
  	unsigned short data;
  	int ret;
  
  	ret = ad5398_read_reg(client, &data);
  	if (ret < 0)
  		return ret;
  
  	if (data & AD5398_CURRENT_EN_MASK)
  		return 1;
  	else
  		return 0;
  }
  
  static int ad5398_enable(struct regulator_dev *rdev)
  {
  	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
  	struct i2c_client *client = chip->client;
  	unsigned short data;
  	int ret;
  
  	ret = ad5398_read_reg(client, &data);
  	if (ret < 0)
  		return ret;
  
  	if (data & AD5398_CURRENT_EN_MASK)
  		return 0;
  
  	data |= AD5398_CURRENT_EN_MASK;
  
  	ret = ad5398_write_reg(client, data);
  
  	return ret;
  }
  
  static int ad5398_disable(struct regulator_dev *rdev)
  {
  	struct ad5398_chip_info *chip = rdev_get_drvdata(rdev);
  	struct i2c_client *client = chip->client;
  	unsigned short data;
  	int ret;
  
  	ret = ad5398_read_reg(client, &data);
  	if (ret < 0)
  		return ret;
  
  	if (!(data & AD5398_CURRENT_EN_MASK))
  		return 0;
  
  	data &= ~AD5398_CURRENT_EN_MASK;
  
  	ret = ad5398_write_reg(client, data);
  
  	return ret;
  }
  
  static struct regulator_ops ad5398_ops = {
  	.get_current_limit = ad5398_get_current_limit,
  	.set_current_limit = ad5398_set_current_limit,
  	.enable = ad5398_enable,
  	.disable = ad5398_disable,
  	.is_enabled = ad5398_is_enabled,
  };
  
  static const struct regulator_desc ad5398_reg = {
  	.name = "isink",
  	.id = 0,
  	.ops = &ad5398_ops,
  	.type = REGULATOR_CURRENT,
  	.owner = THIS_MODULE,
  };
  
  struct ad5398_current_data_format {
  	int current_bits;
  	int current_offset;
  	int min_uA;
  	int max_uA;
  };
  
  static const struct ad5398_current_data_format df_10_4_120 = {10, 4, 0, 120000};
  
  static const struct i2c_device_id ad5398_id[] = {
  	{ "ad5398", (kernel_ulong_t)&df_10_4_120 },
  	{ "ad5821", (kernel_ulong_t)&df_10_4_120 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, ad5398_id);
  
  static int ad5398_probe(struct i2c_client *client,
  				const struct i2c_device_id *id)
  {
  	struct regulator_init_data *init_data = dev_get_platdata(&client->dev);
  	struct regulator_config config = { };
  	struct ad5398_chip_info *chip;
  	const struct ad5398_current_data_format *df =
  			(struct ad5398_current_data_format *)id->driver_data;
  
  	if (!init_data)
  		return -EINVAL;
  
  	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
  	if (!chip)
  		return -ENOMEM;
  
  	config.dev = &client->dev;
  	config.init_data = init_data;
  	config.driver_data = chip;
  
  	chip->client = client;
  
  	chip->min_uA = df->min_uA;
  	chip->max_uA = df->max_uA;
  	chip->current_level = 1 << df->current_bits;
  	chip->current_offset = df->current_offset;
  	chip->current_mask = (chip->current_level - 1) << chip->current_offset;
  
  	chip->rdev = devm_regulator_register(&client->dev, &ad5398_reg,
  					     &config);
  	if (IS_ERR(chip->rdev)) {
  		dev_err(&client->dev, "failed to register %s %s
  ",
  			id->name, ad5398_reg.name);
  		return PTR_ERR(chip->rdev);
  	}
  
  	i2c_set_clientdata(client, chip);
  	dev_dbg(&client->dev, "%s regulator driver is registered.
  ", id->name);
  	return 0;
  }
  
  static struct i2c_driver ad5398_driver = {
  	.probe = ad5398_probe,
  	.driver		= {
  		.name	= "ad5398",
  	},
  	.id_table	= ad5398_id,
  };
  
  static int __init ad5398_init(void)
  {
  	return i2c_add_driver(&ad5398_driver);
  }
  subsys_initcall(ad5398_init);
  
  static void __exit ad5398_exit(void)
  {
  	i2c_del_driver(&ad5398_driver);
  }
  module_exit(ad5398_exit);
  
  MODULE_DESCRIPTION("AD5398 and AD5821 current regulator driver");
  MODULE_AUTHOR("Sonic Zhang");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("i2c:ad5398-regulator");