/*
   * max1586.c  --  Voltage and current regulation for the Maxim 1586
   *
   * Copyright (C) 2008 Robert Jarzmik
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  #include <linux/module.h>
  #include <linux/err.h>
  #include <linux/i2c.h>
  #include <linux/platform_device.h>
  #include <linux/regulator/driver.h>

  #include <linux/slab.h>

  #include <linux/regulator/max1586.h>
  
  #define MAX1586_V3_MAX_VSEL 31
  #define MAX1586_V6_MAX_VSEL 3
  
  #define MAX1586_V3_MIN_UV   700000
  #define MAX1586_V3_MAX_UV  1475000

  
  #define MAX1586_V6_MIN_UV        0
  #define MAX1586_V6_MAX_UV  3000000
  
  #define I2C_V3_SELECT (0 << 5)
  #define I2C_V6_SELECT (1 << 5)

  struct max1586_data {
  	struct i2c_client *client;
  
  	/* min/max V3 voltage */

  	unsigned int min_uV;
  	unsigned int max_uV;

  
  	struct regulator_dev *rdev[0];
  };

  /*
   * V3 voltage
   * On I2C bus, sending a "x" byte to the max1586 means :
   *   set V3 to 0.700V + (x & 0x1f) * 0.025V

   * This voltage can be increased by external resistors
   * R24 and R25=100kOhm as described in the data sheet.
   * The gain is approximately: 1 + R24/R25 + R24/185.5kOhm

   */

  static int max1586_v3_calc_voltage(struct max1586_data *max1586,
  	unsigned selector)

  {

  	unsigned range_uV = max1586->max_uV - max1586->min_uV;
  
  	return max1586->min_uV + (selector * range_uV / MAX1586_V3_MAX_VSEL);

  }

  static int max1586_v3_set(struct regulator_dev *rdev, int min_uV, int max_uV,
  			  unsigned *selector)

  {

  	struct max1586_data *max1586 = rdev_get_drvdata(rdev);
  	struct i2c_client *client = max1586->client;
  	unsigned range_uV = max1586->max_uV - max1586->min_uV;

  	u8 v3_prog;

  	if (min_uV > max1586->max_uV || max_uV < max1586->min_uV)

  		return -EINVAL;

  	if (min_uV < max1586->min_uV)
  		min_uV = max1586->min_uV;

  	*selector = ((min_uV - max1586->min_uV) * MAX1586_V3_MAX_VSEL +

  			range_uV - 1) / range_uV;

  	if (max1586_v3_calc_voltage(max1586, *selector) > max_uV)

  		return -EINVAL;
  
  	dev_dbg(&client->dev, "changing voltage v3 to %dmv
  ",

  		max1586_v3_calc_voltage(max1586, *selector) / 1000);

  	v3_prog = I2C_V3_SELECT | (u8) *selector;

  	return i2c_smbus_write_byte(client, v3_prog);
  }
  
  static int max1586_v3_list(struct regulator_dev *rdev, unsigned selector)
  {

  	struct max1586_data *max1586 = rdev_get_drvdata(rdev);

  	if (selector > MAX1586_V3_MAX_VSEL)
  		return -EINVAL;

  	return max1586_v3_calc_voltage(max1586, selector);

  }
  
  /*
   * V6 voltage
   * On I2C bus, sending a "x" byte to the max1586 means :
   *   set V6 to either 0V, 1.8V, 2.5V, 3V depending on (x & 0x3)
   * As regulator framework doesn't accept voltages to be 0V, we use 1uV.
   */
  static int max1586_v6_calc_voltage(unsigned selector)
  {
  	static int voltages_uv[] = { 1, 1800000, 2500000, 3000000 };
  
  	return voltages_uv[selector];
  }

  static int max1586_v6_set(struct regulator_dev *rdev, int min_uV, int max_uV,
  			  unsigned int *selector)

  {
  	struct i2c_client *client = rdev_get_drvdata(rdev);

  	u8 v6_prog;
  
  	if (min_uV < MAX1586_V6_MIN_UV || min_uV > MAX1586_V6_MAX_UV)
  		return -EINVAL;
  	if (max_uV < MAX1586_V6_MIN_UV || max_uV > MAX1586_V6_MAX_UV)
  		return -EINVAL;

  	if (min_uV < 1800000)

  		*selector = 0;

  	else if (min_uV < 2500000)

  		*selector = 1;

  	else if (min_uV < 3000000)

  		*selector = 2;

  	else if (min_uV >= 3000000)

  		*selector = 3;

  	if (max1586_v6_calc_voltage(*selector) > max_uV)

  		return -EINVAL;
  
  	dev_dbg(&client->dev, "changing voltage v6 to %dmv
  ",

  		max1586_v6_calc_voltage(*selector) / 1000);

  	v6_prog = I2C_V6_SELECT | (u8) *selector;

  	return i2c_smbus_write_byte(client, v6_prog);
  }
  
  static int max1586_v6_list(struct regulator_dev *rdev, unsigned selector)
  {
  	if (selector > MAX1586_V6_MAX_VSEL)
  		return -EINVAL;
  	return max1586_v6_calc_voltage(selector);
  }
  
  /*
   * The Maxim 1586 controls V3 and V6 voltages, but offers no way of reading back
   * the set up value.
   */
  static struct regulator_ops max1586_v3_ops = {
  	.set_voltage = max1586_v3_set,
  	.list_voltage = max1586_v3_list,
  };
  
  static struct regulator_ops max1586_v6_ops = {
  	.set_voltage = max1586_v6_set,
  	.list_voltage = max1586_v6_list,
  };
  
  static struct regulator_desc max1586_reg[] = {
  	{
  		.name = "Output_V3",
  		.id = MAX1586_V3,
  		.ops = &max1586_v3_ops,
  		.type = REGULATOR_VOLTAGE,
  		.n_voltages = MAX1586_V3_MAX_VSEL + 1,
  		.owner = THIS_MODULE,
  	},
  	{
  		.name = "Output_V6",
  		.id = MAX1586_V6,
  		.ops = &max1586_v6_ops,
  		.type = REGULATOR_VOLTAGE,
  		.n_voltages = MAX1586_V6_MAX_VSEL + 1,
  		.owner = THIS_MODULE,
  	},
  };

  static int __devinit max1586_pmic_probe(struct i2c_client *client,
  					const struct i2c_device_id *i2c_id)

  {
  	struct regulator_dev **rdev;
  	struct max1586_platform_data *pdata = client->dev.platform_data;

  	struct max1586_data *max1586;
  	int i, id, ret = -ENOMEM;
  
  	max1586 = kzalloc(sizeof(struct max1586_data) +
  			sizeof(struct regulator_dev *) * (MAX1586_V6 + 1),
  			GFP_KERNEL);
  	if (!max1586)
  		goto out;

  	max1586->client = client;

  	if (!pdata->v3_gain) {
  		ret = -EINVAL;
  		goto out_unmap;
  	}

  	max1586->min_uV = MAX1586_V3_MIN_UV / 1000 * pdata->v3_gain / 1000;
  	max1586->max_uV = MAX1586_V3_MAX_UV / 1000 * pdata->v3_gain / 1000;

  
  	rdev = max1586->rdev;

  	for (i = 0; i < pdata->num_subdevs && i <= MAX1586_V6; i++) {
  		id = pdata->subdevs[i].id;
  		if (!pdata->subdevs[i].platform_data)
  			continue;
  		if (id < MAX1586_V3 || id > MAX1586_V6) {
  			dev_err(&client->dev, "invalid regulator id %d
  ", id);
  			goto err;
  		}
  		rdev[i] = regulator_register(&max1586_reg[id], &client->dev,
  					     pdata->subdevs[i].platform_data,

  					     max1586);

  		if (IS_ERR(rdev[i])) {
  			ret = PTR_ERR(rdev[i]);
  			dev_err(&client->dev, "failed to register %s
  ",
  				max1586_reg[id].name);
  			goto err;
  		}
  	}

  	i2c_set_clientdata(client, max1586);

  	dev_info(&client->dev, "Maxim 1586 regulator driver loaded
  ");
  	return 0;
  
  err:
  	while (--i >= 0)
  		regulator_unregister(rdev[i]);

  out_unmap:
  	kfree(max1586);
  out:

  	return ret;
  }

  static int __devexit max1586_pmic_remove(struct i2c_client *client)

  {

  	struct max1586_data *max1586 = i2c_get_clientdata(client);

  	int i;
  
  	for (i = 0; i <= MAX1586_V6; i++)

  		if (max1586->rdev[i])
  			regulator_unregister(max1586->rdev[i]);
  	kfree(max1586);

  
  	return 0;
  }
  
  static const struct i2c_device_id max1586_id[] = {
  	{ "max1586", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, max1586_id);
  
  static struct i2c_driver max1586_pmic_driver = {
  	.probe = max1586_pmic_probe,

  	.remove = __devexit_p(max1586_pmic_remove),

  	.driver		= {
  		.name	= "max1586",

  		.owner	= THIS_MODULE,

  	},
  	.id_table	= max1586_id,
  };
  
  static int __init max1586_pmic_init(void)
  {
  	return i2c_add_driver(&max1586_pmic_driver);
  }
  subsys_initcall(max1586_pmic_init);
  
  static void __exit max1586_pmic_exit(void)
  {
  	i2c_del_driver(&max1586_pmic_driver);
  }
  module_exit(max1586_pmic_exit);
  
  /* Module information */
  MODULE_DESCRIPTION("MAXIM 1586 voltage regulator driver");
  MODULE_AUTHOR("Robert Jarzmik");
  MODULE_LICENSE("GPL");