/*
   * 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/module.h>

  #include <linux/slab.h>
  #include <linux/i2c.h>

  #include <linux/delay.h>

  #include <linux/interrupt.h>

  #include <linux/pm.h>

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

  #include <linux/of.h>

  #include <linux/regmap.h>

  /* Status register bits */
  #define STATUS_POR_BIT         (1 << 1)
  #define STATUS_BST_BIT         (1 << 3)
  #define STATUS_VMN_BIT         (1 << 8)
  #define STATUS_TMN_BIT         (1 << 9)
  #define STATUS_SMN_BIT         (1 << 10)
  #define STATUS_BI_BIT          (1 << 11)
  #define STATUS_VMX_BIT         (1 << 12)
  #define STATUS_TMX_BIT         (1 << 13)
  #define STATUS_SMX_BIT         (1 << 14)
  #define STATUS_BR_BIT          (1 << 15)

  /* Interrupt mask bits */
  #define CONFIG_ALRT_BIT_ENBL	(1 << 2)

  #define STATUS_INTR_SOCMIN_BIT	(1 << 10)
  #define STATUS_INTR_SOCMAX_BIT	(1 << 14)

  #define VFSOC0_LOCK		0x0000
  #define VFSOC0_UNLOCK		0x0080
  #define MODEL_UNLOCK1	0X0059
  #define MODEL_UNLOCK2	0X00C4
  #define MODEL_LOCK1		0X0000
  #define MODEL_LOCK2		0X0000
  
  #define dQ_ACC_DIV	0x4
  #define dP_ACC_100	0x1900
  #define dP_ACC_200	0x3200

  #define MAX17042_IC_VERSION	0x0092
  #define MAX17047_IC_VERSION	0x00AC	/* same for max17050 */

  struct max17042_chip {
  	struct i2c_client *client;

  	struct regmap *regmap;

  	struct power_supply battery;

  	enum max170xx_chip_type chip_type;

  	struct max17042_platform_data *pdata;

  	struct work_struct work;
  	int    init_complete;

  };

  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_VOLTAGE_OCV,

  	POWER_SUPPLY_PROP_CAPACITY,

  	POWER_SUPPLY_PROP_CHARGE_FULL,

  	POWER_SUPPLY_PROP_CHARGE_COUNTER,

  	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);

  	struct regmap *map = chip->regmap;

  	int ret;

  	u32 data;

  	if (!chip->init_complete)
  		return -EAGAIN;

  	switch (psp) {

  	case POWER_SUPPLY_PROP_PRESENT:

  		ret = regmap_read(map, MAX17042_STATUS, &data);

  		if (ret < 0)
  			return ret;

  		if (data & MAX17042_STATUS_BattAbsent)

  			val->intval = 0;
  		else
  			val->intval = 1;
  		break;
  	case POWER_SUPPLY_PROP_CYCLE_COUNT:

  		ret = regmap_read(map, MAX17042_Cycles, &data);

  		if (ret < 0)
  			return ret;

  		val->intval = data;

  		break;
  	case POWER_SUPPLY_PROP_VOLTAGE_MAX:

  		ret = regmap_read(map, MAX17042_MinMaxVolt, &data);

  		if (ret < 0)
  			return ret;

  		val->intval = data >> 8;

  		val->intval *= 20000; /* Units of LSB = 20mV */
  		break;
  	case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:

  		if (chip->chip_type == MAX17042)

  			ret = regmap_read(map, MAX17042_V_empty, &data);

  		else

  			ret = regmap_read(map, MAX17047_V_empty, &data);

  		if (ret < 0)
  			return ret;

  		val->intval = data >> 7;

  		val->intval *= 10000; /* Units of LSB = 10mV */
  		break;

  	case POWER_SUPPLY_PROP_VOLTAGE_NOW:

  		ret = regmap_read(map, MAX17042_VCELL, &data);

  		if (ret < 0)
  			return ret;

  		val->intval = data * 625 / 8;

  		break;
  	case POWER_SUPPLY_PROP_VOLTAGE_AVG:

  		ret = regmap_read(map, MAX17042_AvgVCELL, &data);

  		if (ret < 0)
  			return ret;

  		val->intval = data * 625 / 8;

  		break;

  	case POWER_SUPPLY_PROP_VOLTAGE_OCV:

  		ret = regmap_read(map, MAX17042_OCVInternal, &data);

  		if (ret < 0)
  			return ret;

  		val->intval = data * 625 / 8;

  		break;

  	case POWER_SUPPLY_PROP_CAPACITY:

  		ret = regmap_read(map, MAX17042_RepSOC, &data);

  		if (ret < 0)
  			return ret;

  		val->intval = data >> 8;

  		break;

  	case POWER_SUPPLY_PROP_CHARGE_FULL:

  		ret = regmap_read(map, MAX17042_FullCAP, &data);

  		if (ret < 0)
  			return ret;

  		val->intval = data * 1000 / 2;

  		break;

  	case POWER_SUPPLY_PROP_CHARGE_COUNTER:

  		ret = regmap_read(map, MAX17042_QH, &data);

  		if (ret < 0)
  			return ret;

  		val->intval = data * 1000 / 2;

  		break;

  	case POWER_SUPPLY_PROP_TEMP:

  		ret = regmap_read(map, MAX17042_TEMP, &data);

  		if (ret < 0)
  			return ret;

  		val->intval = data;

  		/* 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) {

  			ret = regmap_read(map, MAX17042_Current, &data);

  			if (ret < 0)
  				return ret;

  			val->intval = data;

  			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;
  	case POWER_SUPPLY_PROP_CURRENT_AVG:
  		if (chip->pdata->enable_current_sense) {

  			ret = regmap_read(map, MAX17042_AvgCurrent, &data);

  			if (ret < 0)
  				return ret;

  			val->intval = data;

  			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 max17042_write_verify_reg(struct regmap *map, u8 reg, u32 value)

  {
  	int retries = 8;
  	int ret;

  	u32 read_value;

  
  	do {

  		ret = regmap_write(map, reg, value);
  		regmap_read(map, reg, &read_value);

  		if (read_value != value) {
  			ret = -EIO;
  			retries--;
  		}
  	} while (retries && read_value != value);
  
  	if (ret < 0)

  		pr_err("%s: err %d
  ", __func__, ret);

  
  	return ret;
  }

  static inline void max17042_override_por(struct regmap *map,
  					 u8 reg, u16 value)

  {
  	if (value)

  		regmap_write(map, reg, value);

  }
  
  static inline void max10742_unlock_model(struct max17042_chip *chip)
  {

  	struct regmap *map = chip->regmap;
  	regmap_write(map, MAX17042_MLOCKReg1, MODEL_UNLOCK1);
  	regmap_write(map, MAX17042_MLOCKReg2, MODEL_UNLOCK2);

  }
  
  static inline void max10742_lock_model(struct max17042_chip *chip)
  {

  	struct regmap *map = chip->regmap;
  
  	regmap_write(map, MAX17042_MLOCKReg1, MODEL_LOCK1);
  	regmap_write(map, MAX17042_MLOCKReg2, MODEL_LOCK2);

  }
  
  static inline void max17042_write_model_data(struct max17042_chip *chip,
  					u8 addr, int size)
  {

  	struct regmap *map = chip->regmap;

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

  		regmap_write(map, addr + i,
  			chip->pdata->config_data->cell_char_tbl[i]);

  }
  
  static inline void max17042_read_model_data(struct max17042_chip *chip,

  					u8 addr, u32 *data, int size)

  {

  	struct regmap *map = chip->regmap;

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

  		regmap_read(map, addr + i, &data[i]);

  }
  
  static inline int max17042_model_data_compare(struct max17042_chip *chip,
  					u16 *data1, u16 *data2, int size)
  {
  	int i;
  
  	if (memcmp(data1, data2, size)) {
  		dev_err(&chip->client->dev, "%s compare failed
  ", __func__);
  		for (i = 0; i < size; i++)
  			dev_info(&chip->client->dev, "0x%x, 0x%x",
  				data1[i], data2[i]);
  		dev_info(&chip->client->dev, "
  ");
  		return -EINVAL;
  	}
  	return 0;
  }
  
  static int max17042_init_model(struct max17042_chip *chip)
  {
  	int ret;

  	int table_size = ARRAY_SIZE(chip->pdata->config_data->cell_char_tbl);

  	u32 *temp_data;

  	temp_data = kcalloc(table_size, sizeof(*temp_data), GFP_KERNEL);

  	if (!temp_data)
  		return -ENOMEM;
  
  	max10742_unlock_model(chip);
  	max17042_write_model_data(chip, MAX17042_MODELChrTbl,
  				table_size);
  	max17042_read_model_data(chip, MAX17042_MODELChrTbl, temp_data,
  				table_size);
  
  	ret = max17042_model_data_compare(
  		chip,
  		chip->pdata->config_data->cell_char_tbl,

  		(u16 *)temp_data,

  		table_size);
  
  	max10742_lock_model(chip);
  	kfree(temp_data);
  
  	return ret;
  }
  
  static int max17042_verify_model_lock(struct max17042_chip *chip)
  {
  	int i;

  	int table_size = ARRAY_SIZE(chip->pdata->config_data->cell_char_tbl);

  	u32 *temp_data;

  	int ret = 0;

  	temp_data = kcalloc(table_size, sizeof(*temp_data), GFP_KERNEL);

  	if (!temp_data)
  		return -ENOMEM;
  
  	max17042_read_model_data(chip, MAX17042_MODELChrTbl, temp_data,
  				table_size);
  	for (i = 0; i < table_size; i++)
  		if (temp_data[i])
  			ret = -EINVAL;
  
  	kfree(temp_data);
  	return ret;
  }
  
  static void max17042_write_config_regs(struct max17042_chip *chip)
  {
  	struct max17042_config_data *config = chip->pdata->config_data;

  	struct regmap *map = chip->regmap;

  	regmap_write(map, MAX17042_CONFIG, config->config);
  	regmap_write(map, MAX17042_LearnCFG, config->learn_cfg);
  	regmap_write(map, MAX17042_FilterCFG,

  			config->filter_cfg);

  	regmap_write(map, MAX17042_RelaxCFG, config->relax_cfg);

  	if (chip->chip_type == MAX17047)

  		regmap_write(map, MAX17047_FullSOCThr,

  						config->full_soc_thresh);

  }
  
  static void  max17042_write_custom_regs(struct max17042_chip *chip)
  {
  	struct max17042_config_data *config = chip->pdata->config_data;

  	struct regmap *map = chip->regmap;

  	max17042_write_verify_reg(map, MAX17042_RCOMP0, config->rcomp0);
  	max17042_write_verify_reg(map, MAX17042_TempCo,	config->tcompc0);
  	max17042_write_verify_reg(map, MAX17042_ICHGTerm, config->ichgt_term);

  	if (chip->chip_type == MAX17042) {

  		regmap_write(map, MAX17042_EmptyTempCo,	config->empty_tempco);
  		max17042_write_verify_reg(map, MAX17042_K_empty0,

  					config->kempty0);
  	} else {

  		max17042_write_verify_reg(map, MAX17047_QRTbl00,

  						config->qrtbl00);

  		max17042_write_verify_reg(map, MAX17047_QRTbl10,

  						config->qrtbl10);

  		max17042_write_verify_reg(map, MAX17047_QRTbl20,

  						config->qrtbl20);

  		max17042_write_verify_reg(map, MAX17047_QRTbl30,

  						config->qrtbl30);
  	}

  }
  
  static void max17042_update_capacity_regs(struct max17042_chip *chip)
  {
  	struct max17042_config_data *config = chip->pdata->config_data;

  	struct regmap *map = chip->regmap;

  	max17042_write_verify_reg(map, MAX17042_FullCAP,

  				config->fullcap);

  	regmap_write(map, MAX17042_DesignCap, config->design_cap);
  	max17042_write_verify_reg(map, MAX17042_FullCAPNom,

  				config->fullcapnom);
  }
  
  static void max17042_reset_vfsoc0_reg(struct max17042_chip *chip)
  {

  	unsigned int vfSoc;
  	struct regmap *map = chip->regmap;

  	regmap_read(map, MAX17042_VFSOC, &vfSoc);
  	regmap_write(map, MAX17042_VFSOC0Enable, VFSOC0_UNLOCK);
  	max17042_write_verify_reg(map, MAX17042_VFSOC0, vfSoc);
  	regmap_write(map, MAX17042_VFSOC0Enable, VFSOC0_LOCK);

  }
  
  static void max17042_load_new_capacity_params(struct max17042_chip *chip)
  {

  	u32 full_cap0, rep_cap, dq_acc, vfSoc;

  	u32 rem_cap;
  
  	struct max17042_config_data *config = chip->pdata->config_data;

  	struct regmap *map = chip->regmap;

  	regmap_read(map, MAX17042_FullCAP0, &full_cap0);
  	regmap_read(map, MAX17042_VFSOC, &vfSoc);

  
  	/* fg_vfSoc needs to shifted by 8 bits to get the
  	 * perc in 1% accuracy, to get the right rem_cap multiply
  	 * full_cap0, fg_vfSoc and devide by 100
  	 */
  	rem_cap = ((vfSoc >> 8) * full_cap0) / 100;

  	max17042_write_verify_reg(map, MAX17042_RemCap, rem_cap);

  	rep_cap = rem_cap;
  	max17042_write_verify_reg(map, MAX17042_RepCap, rep_cap);

  
  	/* Write dQ_acc to 200% of Capacity and dP_acc to 200% */
  	dq_acc = config->fullcap / dQ_ACC_DIV;

  	max17042_write_verify_reg(map, MAX17042_dQacc, dq_acc);
  	max17042_write_verify_reg(map, MAX17042_dPacc, dP_ACC_200);

  	max17042_write_verify_reg(map, MAX17042_FullCAP,

  			config->fullcap);

  	regmap_write(map, MAX17042_DesignCap,

  			config->design_cap);

  	max17042_write_verify_reg(map, MAX17042_FullCAPNom,

  			config->fullcapnom);

  	/* Update SOC register with new SOC */

  	regmap_write(map, MAX17042_RepSOC, vfSoc);

  }
  
  /*
   * Block write all the override values coming from platform data.
   * This function MUST be called before the POR initialization proceedure
   * specified by maxim.
   */
  static inline void max17042_override_por_values(struct max17042_chip *chip)
  {

  	struct regmap *map = chip->regmap;

  	struct max17042_config_data *config = chip->pdata->config_data;

  	max17042_override_por(map, MAX17042_TGAIN, config->tgain);
  	max17042_override_por(map, MAx17042_TOFF, config->toff);
  	max17042_override_por(map, MAX17042_CGAIN, config->cgain);
  	max17042_override_por(map, MAX17042_COFF, config->coff);
  
  	max17042_override_por(map, MAX17042_VALRT_Th, config->valrt_thresh);
  	max17042_override_por(map, MAX17042_TALRT_Th, config->talrt_thresh);
  	max17042_override_por(map, MAX17042_SALRT_Th,
  						config->soc_alrt_thresh);
  	max17042_override_por(map, MAX17042_CONFIG, config->config);
  	max17042_override_por(map, MAX17042_SHDNTIMER, config->shdntimer);
  
  	max17042_override_por(map, MAX17042_DesignCap, config->design_cap);
  	max17042_override_por(map, MAX17042_ICHGTerm, config->ichgt_term);
  
  	max17042_override_por(map, MAX17042_AtRate, config->at_rate);
  	max17042_override_por(map, MAX17042_LearnCFG, config->learn_cfg);
  	max17042_override_por(map, MAX17042_FilterCFG, config->filter_cfg);
  	max17042_override_por(map, MAX17042_RelaxCFG, config->relax_cfg);
  	max17042_override_por(map, MAX17042_MiscCFG, config->misc_cfg);
  	max17042_override_por(map, MAX17042_MaskSOC, config->masksoc);
  
  	max17042_override_por(map, MAX17042_FullCAP, config->fullcap);
  	max17042_override_por(map, MAX17042_FullCAPNom, config->fullcapnom);

  	if (chip->chip_type == MAX17042)

  		max17042_override_por(map, MAX17042_SOC_empty,

  						config->socempty);

  	max17042_override_por(map, MAX17042_LAvg_empty, config->lavg_empty);
  	max17042_override_por(map, MAX17042_dQacc, config->dqacc);
  	max17042_override_por(map, MAX17042_dPacc, config->dpacc);

  	if (chip->chip_type == MAX17042)

  		max17042_override_por(map, MAX17042_V_empty, config->vempty);

  	else

  		max17042_override_por(map, MAX17047_V_empty, config->vempty);
  	max17042_override_por(map, MAX17042_TempNom, config->temp_nom);
  	max17042_override_por(map, MAX17042_TempLim, config->temp_lim);
  	max17042_override_por(map, MAX17042_FCTC, config->fctc);
  	max17042_override_por(map, MAX17042_RCOMP0, config->rcomp0);
  	max17042_override_por(map, MAX17042_TempCo, config->tcompc0);

  	if (chip->chip_type) {

  		max17042_override_por(map, MAX17042_EmptyTempCo,
  						config->empty_tempco);
  		max17042_override_por(map, MAX17042_K_empty0,
  						config->kempty0);

  	}

  }
  
  static int max17042_init_chip(struct max17042_chip *chip)
  {

  	struct regmap *map = chip->regmap;

  	int ret;
  	int val;
  
  	max17042_override_por_values(chip);
  	/* After Power up, the MAX17042 requires 500mS in order
  	 * to perform signal debouncing and initial SOC reporting
  	 */
  	msleep(500);
  
  	/* Initialize configaration */
  	max17042_write_config_regs(chip);
  
  	/* write cell characterization data */
  	ret = max17042_init_model(chip);
  	if (ret) {
  		dev_err(&chip->client->dev, "%s init failed
  ",
  			__func__);
  		return -EIO;
  	}

  
  	ret = max17042_verify_model_lock(chip);

  	if (ret) {
  		dev_err(&chip->client->dev, "%s lock verify failed
  ",
  			__func__);
  		return -EIO;
  	}
  	/* write custom parameters */
  	max17042_write_custom_regs(chip);
  
  	/* update capacity params */
  	max17042_update_capacity_regs(chip);
  
  	/* delay must be atleast 350mS to allow VFSOC
  	 * to be calculated from the new configuration
  	 */
  	msleep(350);
  
  	/* reset vfsoc0 reg */
  	max17042_reset_vfsoc0_reg(chip);
  
  	/* load new capacity params */
  	max17042_load_new_capacity_params(chip);
  
  	/* Init complete, Clear the POR bit */

  	regmap_read(map, MAX17042_STATUS, &val);
  	regmap_write(map, MAX17042_STATUS, val & (~STATUS_POR_BIT));

  	return 0;
  }

  static void max17042_set_soc_threshold(struct max17042_chip *chip, u16 off)
  {

  	struct regmap *map = chip->regmap;
  	u32 soc, soc_tr;

  
  	/* program interrupt thesholds such that we should
  	 * get interrupt for every 'off' perc change in the soc
  	 */

  	regmap_read(map, MAX17042_RepSOC, &soc);
  	soc >>= 8;

  	soc_tr = (soc + off) << 8;
  	soc_tr |= (soc - off);

  	regmap_write(map, MAX17042_SALRT_Th, soc_tr);

  }

  static irqreturn_t max17042_thread_handler(int id, void *dev)
  {
  	struct max17042_chip *chip = dev;

  	u32 val;

  	regmap_read(chip->regmap, MAX17042_STATUS, &val);

  	if ((val & STATUS_INTR_SOCMIN_BIT) ||
  		(val & STATUS_INTR_SOCMAX_BIT)) {

  		dev_info(&chip->client->dev, "SOC threshold INTR
  ");
  		max17042_set_soc_threshold(chip, 1);
  	}
  
  	power_supply_changed(&chip->battery);
  	return IRQ_HANDLED;
  }

  
  static void max17042_init_worker(struct work_struct *work)
  {
  	struct max17042_chip *chip = container_of(work,
  				struct max17042_chip, work);
  	int ret;
  
  	/* Initialize registers according to values from the platform data */
  	if (chip->pdata->enable_por_init && chip->pdata->config_data) {
  		ret = max17042_init_chip(chip);
  		if (ret)
  			return;
  	}
  
  	chip->init_complete = 1;
  }

  #ifdef CONFIG_OF
  static struct max17042_platform_data *
  max17042_get_pdata(struct device *dev)
  {
  	struct device_node *np = dev->of_node;
  	u32 prop;
  	struct max17042_platform_data *pdata;
  
  	if (!np)
  		return dev->platform_data;
  
  	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
  	if (!pdata)
  		return NULL;
  
  	/*
  	 * Require current sense resistor value to be specified for
  	 * current-sense functionality to be enabled at all.
  	 */
  	if (of_property_read_u32(np, "maxim,rsns-microohm", &prop) == 0) {
  		pdata->r_sns = prop;
  		pdata->enable_current_sense = true;
  	}
  
  	return pdata;
  }
  #else
  static struct max17042_platform_data *
  max17042_get_pdata(struct device *dev)
  {
  	return dev->platform_data;
  }
  #endif

  static struct regmap_config max17042_regmap_config = {
  	.reg_bits = 8,
  	.val_bits = 16,
  	.val_format_endian = REGMAP_ENDIAN_NATIVE,
  };

  static int 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;

  	int i;
  	u32 val;

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

  	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);

  	if (!chip)
  		return -ENOMEM;
  
  	chip->client = client;

  	chip->regmap = devm_regmap_init_i2c(client, &max17042_regmap_config);
  	if (IS_ERR(chip->regmap)) {
  		dev_err(&client->dev, "Failed to initialize regmap
  ");
  		return -EINVAL;
  	}

  	chip->pdata = max17042_get_pdata(&client->dev);
  	if (!chip->pdata) {
  		dev_err(&client->dev, "no platform data provided
  ");
  		return -EINVAL;
  	}

  
  	i2c_set_clientdata(client, chip);

  	regmap_read(chip->regmap, MAX17042_DevName, &val);
  	if (val == MAX17042_IC_VERSION) {

  		dev_dbg(&client->dev, "chip type max17042 detected
  ");
  		chip->chip_type = MAX17042;

  	} else if (val == MAX17047_IC_VERSION) {

  		dev_dbg(&client->dev, "chip type max17047/50 detected
  ");
  		chip->chip_type = MAX17047;
  	} else {

  		dev_err(&client->dev, "device version mismatch: %x
  ", val);

  		return -EIO;
  	}
  
  	chip->battery.name		= "max170xx_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;

  	if (chip->pdata->r_sns == 0)
  		chip->pdata->r_sns = MAX17042_DEFAULT_SNS_RESISTOR;

  	if (chip->pdata->init_data)

  		for (i = 0; i < chip->pdata->num_init_data; i++)
  			regmap_write(chip->regmap,
  					chip->pdata->init_data[i].addr,
  					chip->pdata->init_data[i].data);

  	if (!chip->pdata->enable_current_sense) {

  		regmap_write(chip->regmap, MAX17042_CGAIN, 0x0000);
  		regmap_write(chip->regmap, MAX17042_MiscCFG, 0x0003);
  		regmap_write(chip->regmap, MAX17042_LearnCFG, 0x0007);

  	}

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

  	if (client->irq) {

  		ret = request_threaded_irq(client->irq, NULL,

  					max17042_thread_handler,
  					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
  					chip->battery.name, chip);

  		if (!ret) {

  			regmap_read(chip->regmap, MAX17042_CONFIG, &val);
  			val |= CONFIG_ALRT_BIT_ENBL;
  			regmap_write(chip->regmap, MAX17042_CONFIG, val);

  			max17042_set_soc_threshold(chip, 1);

  		} else {
  			client->irq = 0;

  			dev_err(&client->dev, "%s(): cannot get IRQ
  ",
  				__func__);

  		}

  	}

  	regmap_read(chip->regmap, MAX17042_STATUS, &val);
  	if (val & STATUS_POR_BIT) {

  		INIT_WORK(&chip->work, max17042_init_worker);
  		schedule_work(&chip->work);
  	} else {
  		chip->init_complete = 1;
  	}

  	return 0;

  }

  static int max17042_remove(struct i2c_client *client)

  {
  	struct max17042_chip *chip = i2c_get_clientdata(client);

  	if (client->irq)
  		free_irq(client->irq, chip);

  	power_supply_unregister(&chip->battery);

  	return 0;
  }

  #ifdef CONFIG_PM_SLEEP

  static int max17042_suspend(struct device *dev)
  {
  	struct max17042_chip *chip = dev_get_drvdata(dev);

  	/*
  	 * disable the irq and enable irq_wake

  	 * capability to the interrupt line.
  	 */
  	if (chip->client->irq) {
  		disable_irq(chip->client->irq);
  		enable_irq_wake(chip->client->irq);
  	}
  
  	return 0;
  }
  
  static int max17042_resume(struct device *dev)
  {
  	struct max17042_chip *chip = dev_get_drvdata(dev);
  
  	if (chip->client->irq) {
  		disable_irq_wake(chip->client->irq);
  		enable_irq(chip->client->irq);
  		/* re-program the SOC thresholds to 1% change */
  		max17042_set_soc_threshold(chip, 1);
  	}
  
  	return 0;
  }

  #endif

  static SIMPLE_DEV_PM_OPS(max17042_pm_ops, max17042_suspend,
  			max17042_resume);

  #ifdef CONFIG_OF
  static const struct of_device_id max17042_dt_match[] = {
  	{ .compatible = "maxim,max17042" },

  	{ .compatible = "maxim,max17047" },
  	{ .compatible = "maxim,max17050" },

  	{ },
  };
  MODULE_DEVICE_TABLE(of, max17042_dt_match);
  #endif

  static const struct i2c_device_id max17042_id[] = {
  	{ "max17042", 0 },

  	{ "max17047", 1 },
  	{ "max17050", 2 },

  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, max17042_id);
  
  static struct i2c_driver max17042_i2c_driver = {
  	.driver	= {
  		.name	= "max17042",

  		.of_match_table = of_match_ptr(max17042_dt_match),

  		.pm	= &max17042_pm_ops,

  	},
  	.probe		= max17042_probe,

  	.remove		= max17042_remove,

  	.id_table	= max17042_id,
  };

  module_i2c_driver(max17042_i2c_driver);

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