/*
 * Fuel gauge driver for Maxim 17042 / 8966 / 8997
 *  Note that Maxim 8966 and 8997 are mfd and this is its subdevice.
 *
 * Copyright (C) 2011 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
 *
 * This driver is based on max17040_battery.c
 */

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/mod_devicetable.h>
#include <linux/power_supply.h>
#include <linux/power/max17042_battery.h>

struct max17042_chip {
	struct i2c_client *client;
	struct power_supply battery;
	struct max17042_platform_data *pdata;
};

static int max17042_write_reg(struct i2c_client *client, u8 reg, u16 value)
{
	int ret = i2c_smbus_write_word_data(client, reg, value);

	if (ret < 0)
		dev_err(&client->dev, "%s: err %d\n", __func__, ret);

	return ret;
}

static int max17042_read_reg(struct i2c_client *client, u8 reg)
{
	int ret = i2c_smbus_read_word_data(client, reg);

	if (ret < 0)
		dev_err(&client->dev, "%s: err %d\n", __func__, ret);

	return ret;
}

static void max17042_set_reg(struct i2c_client *client,
			     struct max17042_reg_data *data, int size)
{
	int i;

	for (i = 0; i < size; i++)
		max17042_write_reg(client, data[i].addr, data[i].data);
}

static enum power_supply_property max17042_battery_props[] = {
	POWER_SUPPLY_PROP_PRESENT,
	POWER_SUPPLY_PROP_CYCLE_COUNT,
	POWER_SUPPLY_PROP_VOLTAGE_MAX,
	POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN,
	POWER_SUPPLY_PROP_VOLTAGE_NOW,
	POWER_SUPPLY_PROP_VOLTAGE_AVG,
	POWER_SUPPLY_PROP_CAPACITY,
	POWER_SUPPLY_PROP_CHARGE_FULL,
	POWER_SUPPLY_PROP_TEMP,
	POWER_SUPPLY_PROP_CURRENT_NOW,
	POWER_SUPPLY_PROP_CURRENT_AVG,
};

static int max17042_get_property(struct power_supply *psy,
			    enum power_supply_property psp,
			    union power_supply_propval *val)
{
	struct max17042_chip *chip = container_of(psy,
				struct max17042_chip, battery);

	switch (psp) {
	case POWER_SUPPLY_PROP_PRESENT:
		val->intval = max17042_read_reg(chip->client,
				MAX17042_STATUS);
		if (val->intval & MAX17042_STATUS_BattAbsent)
			val->intval = 0;
		else
			val->intval = 1;
		break;
	case POWER_SUPPLY_PROP_CYCLE_COUNT:
		val->intval = max17042_read_reg(chip->client,
				MAX17042_Cycles);
		break;
	case POWER_SUPPLY_PROP_VOLTAGE_MAX:
		val->intval = max17042_read_reg(chip->client,
				MAX17042_MinMaxVolt);
		val->intval >>= 8;
		val->intval *= 20000; /* Units of LSB = 20mV */
		break;
	case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
		val->intval = max17042_read_reg(chip->client,
				MAX17042_V_empty);
		val->intval >>= 7;
		val->intval *= 10000; /* Units of LSB = 10mV */
		break;
	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
		val->intval = max17042_read_reg(chip->client,
				MAX17042_VCELL) * 83; /* 1000 / 12 = 83 */
		break;
	case POWER_SUPPLY_PROP_VOLTAGE_AVG:
		val->intval = max17042_read_reg(chip->client,
				MAX17042_AvgVCELL) * 83;
		break;
	case POWER_SUPPLY_PROP_CAPACITY:
		val->intval = max17042_read_reg(chip->client,
				MAX17042_SOC) / 256;
		break;
	case POWER_SUPPLY_PROP_CHARGE_FULL:
		val->intval = max17042_read_reg(chip->client,
				MAX17042_RepSOC);
		if ((val->intval / 256) >= MAX17042_BATTERY_FULL)
			val->intval = 1;
		else if (val->intval >= 0)
			val->intval = 0;
		break;
	case POWER_SUPPLY_PROP_TEMP:
		val->intval = max17042_read_reg(chip->client,
				MAX17042_TEMP);
		/* The value is signed. */
		if (val->intval & 0x8000) {
			val->intval = (0x7fff & ~val->intval) + 1;
			val->intval *= -1;
		}
		/* The value is converted into deci-centigrade scale */
		/* Units of LSB = 1 / 256 degree Celsius */
		val->intval = val->intval * 10 / 256;
		break;
	case POWER_SUPPLY_PROP_CURRENT_NOW:
		if (chip->pdata->enable_current_sense) {
			val->intval = max17042_read_reg(chip->client,
					MAX17042_Current);
			if (val->intval & 0x8000) {
				/* Negative */
				val->intval = ~val->intval & 0x7fff;
				val->intval++;
				val->intval *= -1;
			}
			val->intval >>= 4;
			val->intval *= 1000000 * 25 / chip->pdata->r_sns;
		} else {
			return -EINVAL;
		}
		break;
	case POWER_SUPPLY_PROP_CURRENT_AVG:
		if (chip->pdata->enable_current_sense) {
			val->intval = max17042_read_reg(chip->client,
					MAX17042_AvgCurrent);
			if (val->intval & 0x8000) {
				/* Negative */
				val->intval = ~val->intval & 0x7fff;
				val->intval++;
				val->intval *= -1;
			}
			val->intval *= 1562500 / chip->pdata->r_sns;
		} else {
			return -EINVAL;
		}
		break;
	default:
		return -EINVAL;
	}
	return 0;
}

static int __devinit max17042_probe(struct i2c_client *client,
			const struct i2c_device_id *id)
{
	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
	struct max17042_chip *chip;
	int ret;

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA))
		return -EIO;

	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
	if (!chip)
		return -ENOMEM;

	chip->client = client;
	chip->pdata = client->dev.platform_data;

	i2c_set_clientdata(client, chip);

	chip->battery.name		= "max17042_battery";
	chip->battery.type		= POWER_SUPPLY_TYPE_BATTERY;
	chip->battery.get_property	= max17042_get_property;
	chip->battery.properties	= max17042_battery_props;
	chip->battery.num_properties	= ARRAY_SIZE(max17042_battery_props);

	/* When current is not measured,
	 * CURRENT_NOW and CURRENT_AVG properties should be invisible. */
	if (!chip->pdata->enable_current_sense)
		chip->battery.num_properties -= 2;

	ret = power_supply_register(&client->dev, &chip->battery);
	if (ret) {
		dev_err(&client->dev, "failed: power supply register\n");
		kfree(chip);
		return ret;
	}

	/* Initialize registers according to values from the platform data */
	if (chip->pdata->init_data)
		max17042_set_reg(client, chip->pdata->init_data,
				 chip->pdata->num_init_data);

	if (!chip->pdata->enable_current_sense) {
		max17042_write_reg(client, MAX17042_CGAIN, 0x0000);
		max17042_write_reg(client, MAX17042_MiscCFG, 0x0003);
		max17042_write_reg(client, MAX17042_LearnCFG, 0x0007);
	} else {
		if (chip->pdata->r_sns == 0)
			chip->pdata->r_sns = MAX17042_DEFAULT_SNS_RESISTOR;
	}

	return 0;
}

static int __devexit max17042_remove(struct i2c_client *client)
{
	struct max17042_chip *chip = i2c_get_clientdata(client);

	power_supply_unregister(&chip->battery);
	kfree(chip);
	return 0;
}

static const struct i2c_device_id max17042_id[] = {
	{ "max17042", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, max17042_id);

static struct i2c_driver max17042_i2c_driver = {
	.driver	= {
		.name	= "max17042",
	},
	.probe		= max17042_probe,
	.remove		= __devexit_p(max17042_remove),
	.id_table	= max17042_id,
};

static int __init max17042_init(void)
{
	return i2c_add_driver(&max17042_i2c_driver);
}
module_init(max17042_init);

static void __exit max17042_exit(void)
{
	i2c_del_driver(&max17042_i2c_driver);
}
module_exit(max17042_exit);

MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
MODULE_DESCRIPTION("MAX17042 Fuel Gauge");
MODULE_LICENSE("GPL");