/*
   * max8952.c - Voltage and current regulation for the Maxim 8952
   *
   * Copyright (C) 2010 Samsung Electronics
   * MyungJoo Ham <myungjoo.ham@samsung.com>
   *
   * 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/init.h>
  #include <linux/i2c.h>
  #include <linux/err.h>
  #include <linux/platform_device.h>
  #include <linux/regulator/driver.h>
  #include <linux/regulator/max8952.h>

  #include <linux/gpio.h>
  #include <linux/io.h>
  #include <linux/slab.h>
  
  /* Registers */
  enum {
  	MAX8952_REG_MODE0,
  	MAX8952_REG_MODE1,
  	MAX8952_REG_MODE2,
  	MAX8952_REG_MODE3,
  	MAX8952_REG_CONTROL,
  	MAX8952_REG_SYNC,
  	MAX8952_REG_RAMP,
  	MAX8952_REG_CHIP_ID1,
  	MAX8952_REG_CHIP_ID2,
  };
  
  struct max8952_data {
  	struct i2c_client	*client;
  	struct device		*dev;

  	struct max8952_platform_data *pdata;
  	struct regulator_dev	*rdev;
  
  	bool vid0;
  	bool vid1;
  	bool en;
  };
  
  static int max8952_read_reg(struct max8952_data *max8952, u8 reg)
  {
  	int ret = i2c_smbus_read_byte_data(max8952->client, reg);
  	if (ret > 0)
  		ret &= 0xff;
  
  	return ret;
  }
  
  static int max8952_write_reg(struct max8952_data *max8952,
  		u8 reg, u8 value)
  {
  	return i2c_smbus_write_byte_data(max8952->client, reg, value);
  }
  
  static int max8952_voltage(struct max8952_data *max8952, u8 mode)
  {
  	return (max8952->pdata->dvs_mode[mode] * 10 + 770) * 1000;
  }
  
  static int max8952_list_voltage(struct regulator_dev *rdev,
  		unsigned int selector)
  {
  	struct max8952_data *max8952 = rdev_get_drvdata(rdev);
  
  	if (rdev_get_id(rdev) != 0)
  		return -EINVAL;
  
  	return max8952_voltage(max8952, selector);
  }
  
  static int max8952_is_enabled(struct regulator_dev *rdev)
  {
  	struct max8952_data *max8952 = rdev_get_drvdata(rdev);
  	return max8952->en;
  }
  
  static int max8952_enable(struct regulator_dev *rdev)
  {
  	struct max8952_data *max8952 = rdev_get_drvdata(rdev);
  
  	/* If not valid, assume "ALWAYS_HIGH" */
  	if (gpio_is_valid(max8952->pdata->gpio_en))
  		gpio_set_value(max8952->pdata->gpio_en, 1);
  
  	max8952->en = true;
  	return 0;
  }
  
  static int max8952_disable(struct regulator_dev *rdev)
  {
  	struct max8952_data *max8952 = rdev_get_drvdata(rdev);
  
  	/* If not valid, assume "ALWAYS_HIGH" -> not permitted */
  	if (gpio_is_valid(max8952->pdata->gpio_en))
  		gpio_set_value(max8952->pdata->gpio_en, 0);
  	else
  		return -EPERM;
  
  	max8952->en = false;
  	return 0;
  }
  
  static int max8952_get_voltage(struct regulator_dev *rdev)
  {
  	struct max8952_data *max8952 = rdev_get_drvdata(rdev);
  	u8 vid = 0;
  
  	if (max8952->vid0)
  		vid += 1;
  	if (max8952->vid1)
  		vid += 2;
  
  	return max8952_voltage(max8952, vid);
  }
  
  static int max8952_set_voltage(struct regulator_dev *rdev,

  			       int min_uV, int max_uV, unsigned *selector)

  {
  	struct max8952_data *max8952 = rdev_get_drvdata(rdev);

  	s8 vid = -1, i;

  
  	if (!gpio_is_valid(max8952->pdata->gpio_vid0) ||

  			!gpio_is_valid(max8952->pdata->gpio_vid1)) {

  		/* DVS not supported */
  		return -EPERM;
  	}
  
  	for (i = 0; i < MAX8952_NUM_DVS_MODE; i++) {
  		int volt = max8952_voltage(max8952, i);
  
  		/* Set the voltage as low as possible within the range */
  		if (volt <= max_uV && volt >= min_uV)
  			if (vid == -1 || max8952_voltage(max8952, vid) > volt)
  				vid = i;
  	}
  
  	if (vid >= 0 && vid < MAX8952_NUM_DVS_MODE) {
  		max8952->vid0 = (vid % 2 == 1);
  		max8952->vid1 = (((vid >> 1) % 2) == 1);

  		*selector = vid;

  		gpio_set_value(max8952->pdata->gpio_vid0, max8952->vid0);
  		gpio_set_value(max8952->pdata->gpio_vid1, max8952->vid1);
  	} else
  		return -EINVAL;
  
  	return 0;
  }
  
  static struct regulator_ops max8952_ops = {
  	.list_voltage		= max8952_list_voltage,
  	.is_enabled		= max8952_is_enabled,
  	.enable			= max8952_enable,
  	.disable		= max8952_disable,
  	.get_voltage		= max8952_get_voltage,
  	.set_voltage		= max8952_set_voltage,
  	.set_suspend_disable	= max8952_disable,
  };
  
  static struct regulator_desc regulator = {
  	.name		= "MAX8952_VOUT",
  	.id		= 0,
  	.n_voltages	= MAX8952_NUM_DVS_MODE,
  	.ops		= &max8952_ops,
  	.type		= REGULATOR_VOLTAGE,
  	.owner		= THIS_MODULE,
  };
  
  static int __devinit max8952_pmic_probe(struct i2c_client *client,
  		const struct i2c_device_id *i2c_id)
  {
  	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
  	struct max8952_platform_data *pdata = client->dev.platform_data;
  	struct max8952_data *max8952;
  
  	int ret = 0, err = 0;
  
  	if (!pdata) {
  		dev_err(&client->dev, "Require the platform data
  ");
  		return -EINVAL;
  	}
  
  	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
  		return -EIO;
  
  	max8952 = kzalloc(sizeof(struct max8952_data), GFP_KERNEL);
  	if (!max8952)
  		return -ENOMEM;
  
  	max8952->client = client;
  	max8952->dev = &client->dev;
  	max8952->pdata = pdata;

  
  	max8952->rdev = regulator_register(&regulator, max8952->dev,

  			&pdata->reg_data, max8952, NULL);

  	if (IS_ERR(max8952->rdev)) {
  		ret = PTR_ERR(max8952->rdev);

  		dev_err(max8952->dev, "regulator init failed (%d)
  ", ret);

  		goto err_reg;
  	}

  
  	max8952->en = !!(pdata->reg_data.constraints.boot_on);
  	max8952->vid0 = (pdata->default_mode % 2) == 1;
  	max8952->vid1 = ((pdata->default_mode >> 1) % 2) == 1;
  
  	if (gpio_is_valid(pdata->gpio_en)) {
  		if (!gpio_request(pdata->gpio_en, "MAX8952 EN"))
  			gpio_direction_output(pdata->gpio_en, max8952->en);
  		else
  			err = 1;
  	} else
  		err = 2;
  
  	if (err) {
  		dev_info(max8952->dev, "EN gpio invalid: assume that EN"
  				"is always High
  ");
  		max8952->en = 1;
  		pdata->gpio_en = -1; /* Mark invalid */
  	}
  
  	err = 0;
  
  	if (gpio_is_valid(pdata->gpio_vid0) &&
  			gpio_is_valid(pdata->gpio_vid1)) {
  		if (!gpio_request(pdata->gpio_vid0, "MAX8952 VID0"))
  			gpio_direction_output(pdata->gpio_vid0,
  					(pdata->default_mode) % 2);
  		else
  			err = 1;
  
  		if (!gpio_request(pdata->gpio_vid1, "MAX8952 VID1"))
  			gpio_direction_output(pdata->gpio_vid1,
  				(pdata->default_mode >> 1) % 2);
  		else {
  			if (!err)
  				gpio_free(pdata->gpio_vid0);
  			err = 2;
  		}
  
  	} else
  		err = 3;
  
  	if (err) {
  		dev_warn(max8952->dev, "VID0/1 gpio invalid: "

  				"DVS not available.
  ");

  		max8952->vid0 = 0;
  		max8952->vid1 = 0;
  		/* Mark invalid */
  		pdata->gpio_vid0 = -1;
  		pdata->gpio_vid1 = -1;
  
  		/* Disable Pulldown of EN only */
  		max8952_write_reg(max8952, MAX8952_REG_CONTROL, 0x60);
  
  		dev_err(max8952->dev, "DVS modes disabled because VID0 and VID1"
  				" do not have proper controls.
  ");
  	} else {
  		/*
  		 * Disable Pulldown on EN, VID0, VID1 to reduce
  		 * leakage current of MAX8952 assuming that MAX8952
  		 * is turned on (EN==1). Note that without having VID0/1
  		 * properly connected, turning pulldown off can be
  		 * problematic. Thus, turn this off only when they are
  		 * controllable by GPIO.
  		 */
  		max8952_write_reg(max8952, MAX8952_REG_CONTROL, 0x0);
  	}
  
  	max8952_write_reg(max8952, MAX8952_REG_MODE0,
  			(max8952_read_reg(max8952,
  					  MAX8952_REG_MODE0) & 0xC0) |
  			(pdata->dvs_mode[0] & 0x3F));
  	max8952_write_reg(max8952, MAX8952_REG_MODE1,
  			(max8952_read_reg(max8952,
  					  MAX8952_REG_MODE1) & 0xC0) |
  			(pdata->dvs_mode[1] & 0x3F));
  	max8952_write_reg(max8952, MAX8952_REG_MODE2,
  			(max8952_read_reg(max8952,
  					  MAX8952_REG_MODE2) & 0xC0) |
  			(pdata->dvs_mode[2] & 0x3F));
  	max8952_write_reg(max8952, MAX8952_REG_MODE3,
  			(max8952_read_reg(max8952,
  					  MAX8952_REG_MODE3) & 0xC0) |
  			(pdata->dvs_mode[3] & 0x3F));
  
  	max8952_write_reg(max8952, MAX8952_REG_SYNC,
  			(max8952_read_reg(max8952, MAX8952_REG_SYNC) & 0x3F) |
  			((pdata->sync_freq & 0x3) << 6));
  	max8952_write_reg(max8952, MAX8952_REG_RAMP,
  			(max8952_read_reg(max8952, MAX8952_REG_RAMP) & 0x1F) |
  			((pdata->ramp_speed & 0x7) << 5));
  
  	i2c_set_clientdata(client, max8952);

  	return 0;
  
  err_reg:
  	kfree(max8952);

  	return ret;
  }
  
  static int __devexit max8952_pmic_remove(struct i2c_client *client)
  {
  	struct max8952_data *max8952 = i2c_get_clientdata(client);
  	struct max8952_platform_data *pdata = max8952->pdata;
  	struct regulator_dev *rdev = max8952->rdev;
  
  	regulator_unregister(rdev);
  
  	gpio_free(pdata->gpio_vid0);
  	gpio_free(pdata->gpio_vid1);
  	gpio_free(pdata->gpio_en);
  
  	kfree(max8952);
  	return 0;
  }
  
  static const struct i2c_device_id max8952_ids[] = {
  	{ "max8952", 0 },
  	{ },
  };
  MODULE_DEVICE_TABLE(i2c, max8952_ids);
  
  static struct i2c_driver max8952_pmic_driver = {
  	.probe		= max8952_pmic_probe,
  	.remove		= __devexit_p(max8952_pmic_remove),
  	.driver		= {
  		.name	= "max8952",
  	},
  	.id_table	= max8952_ids,
  };
  
  static int __init max8952_pmic_init(void)
  {
  	return i2c_add_driver(&max8952_pmic_driver);
  }
  subsys_initcall(max8952_pmic_init);
  
  static void __exit max8952_pmic_exit(void)
  {
  	i2c_del_driver(&max8952_pmic_driver);
  }
  module_exit(max8952_pmic_exit);
  
  MODULE_DESCRIPTION("MAXIM 8952 voltage regulator driver");
  MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
  MODULE_LICENSE("GPL");