/*

   * Gas Gauge driver for SBS Compliant Batteries

   *
   * Copyright (c) 2010, NVIDIA Corporation.
   *
   * 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.,
   * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
   */
  
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/err.h>
  #include <linux/power_supply.h>
  #include <linux/i2c.h>
  #include <linux/slab.h>

  #include <linux/interrupt.h>
  #include <linux/gpio.h>

  #include <linux/power/sbs-battery.h>

  
  enum {
  	REG_MANUFACTURER_DATA,
  	REG_TEMPERATURE,
  	REG_VOLTAGE,
  	REG_CURRENT,
  	REG_CAPACITY,
  	REG_TIME_TO_EMPTY,
  	REG_TIME_TO_FULL,
  	REG_STATUS,
  	REG_CYCLE_COUNT,

  	REG_SERIAL_NUMBER,
  	REG_REMAINING_CAPACITY,

  	REG_REMAINING_CAPACITY_CHARGE,

  	REG_FULL_CHARGE_CAPACITY,

  	REG_FULL_CHARGE_CAPACITY_CHARGE,

  	REG_DESIGN_CAPACITY,

  	REG_DESIGN_CAPACITY_CHARGE,

  	REG_DESIGN_VOLTAGE,

  };

  /* Battery Mode defines */
  #define BATTERY_MODE_OFFSET		0x03
  #define BATTERY_MODE_MASK		0x8000

  enum sbs_battery_mode {

  	BATTERY_MODE_AMPS,
  	BATTERY_MODE_WATTS
  };

  /* manufacturer access defines */
  #define MANUFACTURER_ACCESS_STATUS	0x0006
  #define MANUFACTURER_ACCESS_SLEEP	0x0011
  
  /* battery status value bits */

  #define BATTERY_DISCHARGING		0x40

  #define BATTERY_FULL_CHARGED		0x20
  #define BATTERY_FULL_DISCHARGED		0x10

  #define SBS_DATA(_psp, _addr, _min_value, _max_value) { \

  	.psp = _psp, \
  	.addr = _addr, \
  	.min_value = _min_value, \
  	.max_value = _max_value, \
  }

  static const struct chip_data {

  	enum power_supply_property psp;
  	u8 addr;
  	int min_value;
  	int max_value;

  } sbs_data[] = {

  	[REG_MANUFACTURER_DATA] =

  		SBS_DATA(POWER_SUPPLY_PROP_PRESENT, 0x00, 0, 65535),

  	[REG_TEMPERATURE] =

  		SBS_DATA(POWER_SUPPLY_PROP_TEMP, 0x08, 0, 65535),

  	[REG_VOLTAGE] =

  		SBS_DATA(POWER_SUPPLY_PROP_VOLTAGE_NOW, 0x09, 0, 20000),

  	[REG_CURRENT] =

  		SBS_DATA(POWER_SUPPLY_PROP_CURRENT_NOW, 0x0A, -32768, 32767),

  	[REG_CAPACITY] =

  		SBS_DATA(POWER_SUPPLY_PROP_CAPACITY, 0x0E, 0, 100),

  	[REG_REMAINING_CAPACITY] =

  		SBS_DATA(POWER_SUPPLY_PROP_ENERGY_NOW, 0x0F, 0, 65535),

  	[REG_REMAINING_CAPACITY_CHARGE] =

  		SBS_DATA(POWER_SUPPLY_PROP_CHARGE_NOW, 0x0F, 0, 65535),

  	[REG_FULL_CHARGE_CAPACITY] =

  		SBS_DATA(POWER_SUPPLY_PROP_ENERGY_FULL, 0x10, 0, 65535),

  	[REG_FULL_CHARGE_CAPACITY_CHARGE] =

  		SBS_DATA(POWER_SUPPLY_PROP_CHARGE_FULL, 0x10, 0, 65535),

  	[REG_TIME_TO_EMPTY] =

  		SBS_DATA(POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG, 0x12, 0, 65535),

  	[REG_TIME_TO_FULL] =

  		SBS_DATA(POWER_SUPPLY_PROP_TIME_TO_FULL_AVG, 0x13, 0, 65535),

  	[REG_STATUS] =

  		SBS_DATA(POWER_SUPPLY_PROP_STATUS, 0x16, 0, 65535),

  	[REG_CYCLE_COUNT] =

  		SBS_DATA(POWER_SUPPLY_PROP_CYCLE_COUNT, 0x17, 0, 65535),

  	[REG_DESIGN_CAPACITY] =

  		SBS_DATA(POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN, 0x18, 0, 65535),

  	[REG_DESIGN_CAPACITY_CHARGE] =

  		SBS_DATA(POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN, 0x18, 0, 65535),

  	[REG_DESIGN_VOLTAGE] =

  		SBS_DATA(POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN, 0x19, 0, 65535),

  	[REG_SERIAL_NUMBER] =

  		SBS_DATA(POWER_SUPPLY_PROP_SERIAL_NUMBER, 0x1C, 0, 65535),

  };

  static enum power_supply_property sbs_properties[] = {

  	POWER_SUPPLY_PROP_STATUS,
  	POWER_SUPPLY_PROP_HEALTH,
  	POWER_SUPPLY_PROP_PRESENT,
  	POWER_SUPPLY_PROP_TECHNOLOGY,
  	POWER_SUPPLY_PROP_CYCLE_COUNT,
  	POWER_SUPPLY_PROP_VOLTAGE_NOW,
  	POWER_SUPPLY_PROP_CURRENT_NOW,
  	POWER_SUPPLY_PROP_CAPACITY,
  	POWER_SUPPLY_PROP_TEMP,
  	POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG,
  	POWER_SUPPLY_PROP_TIME_TO_FULL_AVG,
  	POWER_SUPPLY_PROP_SERIAL_NUMBER,

  	POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
  	POWER_SUPPLY_PROP_ENERGY_NOW,
  	POWER_SUPPLY_PROP_ENERGY_FULL,
  	POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN,

  	POWER_SUPPLY_PROP_CHARGE_NOW,
  	POWER_SUPPLY_PROP_CHARGE_FULL,
  	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,

  };

  struct sbs_info {

  	struct i2c_client		*client;
  	struct power_supply		power_supply;

  	struct sbs_platform_data	*pdata;

  	bool				is_present;
  	bool				gpio_detect;
  	bool				enable_detection;
  	int				irq;

  	int				last_state;
  	int				poll_time;
  	struct delayed_work		work;
  	int				ignore_changes;

  };

  static int sbs_read_word_data(struct i2c_client *client, u8 address)

  {

  	struct sbs_info *chip = i2c_get_clientdata(client);

  	s32 ret = 0;
  	int retries = 1;

  	if (chip->pdata)
  		retries = max(chip->pdata->i2c_retry_count + 1, 1);

  
  	while (retries > 0) {
  		ret = i2c_smbus_read_word_data(client, address);
  		if (ret >= 0)
  			break;
  		retries--;
  	}

  	if (ret < 0) {

  		dev_dbg(&client->dev,

  			"%s: i2c read at address 0x%x failed
  ",
  			__func__, address);
  		return ret;
  	}

  	return le16_to_cpu(ret);
  }

  static int sbs_write_word_data(struct i2c_client *client, u8 address,

  	u16 value)
  {

  	struct sbs_info *chip = i2c_get_clientdata(client);

  	s32 ret = 0;
  	int retries = 1;

  	if (chip->pdata)
  		retries = max(chip->pdata->i2c_retry_count + 1, 1);

  
  	while (retries > 0) {
  		ret = i2c_smbus_write_word_data(client, address,
  			le16_to_cpu(value));
  		if (ret >= 0)
  			break;
  		retries--;
  	}

  	if (ret < 0) {

  		dev_dbg(&client->dev,

  			"%s: i2c write to address 0x%x failed
  ",
  			__func__, address);
  		return ret;
  	}

  	return 0;
  }

  static int sbs_get_battery_presence_and_health(

  	struct i2c_client *client, enum power_supply_property psp,
  	union power_supply_propval *val)
  {
  	s32 ret;

  	struct sbs_info *chip = i2c_get_clientdata(client);

  
  	if (psp == POWER_SUPPLY_PROP_PRESENT &&

  		chip->gpio_detect) {
  		ret = gpio_get_value(chip->pdata->battery_detect);
  		if (ret == chip->pdata->battery_detect_present)

  			val->intval = 1;
  		else
  			val->intval = 0;

  		chip->is_present = val->intval;

  		return ret;
  	}

  
  	/* Write to ManufacturerAccess with
  	 * ManufacturerAccess command and then
  	 * read the status */

  	ret = sbs_write_word_data(client, sbs_data[REG_MANUFACTURER_DATA].addr,
  					MANUFACTURER_ACCESS_STATUS);

  	if (ret < 0) {
  		if (psp == POWER_SUPPLY_PROP_PRESENT)
  			val->intval = 0; /* battery removed */

  		return ret;

  	}

  	ret = sbs_read_word_data(client, sbs_data[REG_MANUFACTURER_DATA].addr);

  	if (ret < 0)
  		return ret;

  	if (ret < sbs_data[REG_MANUFACTURER_DATA].min_value ||
  	    ret > sbs_data[REG_MANUFACTURER_DATA].max_value) {

  		val->intval = 0;
  		return 0;
  	}
  
  	/* Mask the upper nibble of 2nd byte and
  	 * lower byte of response then
  	 * shift the result by 8 to get status*/
  	ret &= 0x0F00;
  	ret >>= 8;
  	if (psp == POWER_SUPPLY_PROP_PRESENT) {
  		if (ret == 0x0F)
  			/* battery removed */
  			val->intval = 0;
  		else
  			val->intval = 1;
  	} else if (psp == POWER_SUPPLY_PROP_HEALTH) {
  		if (ret == 0x09)
  			val->intval = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
  		else if (ret == 0x0B)
  			val->intval = POWER_SUPPLY_HEALTH_OVERHEAT;
  		else if (ret == 0x0C)
  			val->intval = POWER_SUPPLY_HEALTH_DEAD;
  		else
  			val->intval = POWER_SUPPLY_HEALTH_GOOD;
  	}
  
  	return 0;
  }

  static int sbs_get_battery_property(struct i2c_client *client,

  	int reg_offset, enum power_supply_property psp,
  	union power_supply_propval *val)
  {

  	struct sbs_info *chip = i2c_get_clientdata(client);

  	s32 ret;

  	ret = sbs_read_word_data(client, sbs_data[reg_offset].addr);

  	if (ret < 0)
  		return ret;
  
  	/* returned values are 16 bit */

  	if (sbs_data[reg_offset].min_value < 0)

  		ret = (s16)ret;

  	if (ret >= sbs_data[reg_offset].min_value &&
  	    ret <= sbs_data[reg_offset].max_value) {

  		val->intval = ret;

  		if (psp != POWER_SUPPLY_PROP_STATUS)
  			return 0;
  
  		if (ret & BATTERY_FULL_CHARGED)
  			val->intval = POWER_SUPPLY_STATUS_FULL;
  		else if (ret & BATTERY_FULL_DISCHARGED)
  			val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
  		else if (ret & BATTERY_DISCHARGING)
  			val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
  		else
  			val->intval = POWER_SUPPLY_STATUS_CHARGING;

  		if (chip->poll_time == 0)
  			chip->last_state = val->intval;
  		else if (chip->last_state != val->intval) {
  			cancel_delayed_work_sync(&chip->work);
  			power_supply_changed(&chip->power_supply);
  			chip->poll_time = 0;

  		}

  	} else {
  		if (psp == POWER_SUPPLY_PROP_STATUS)
  			val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
  		else
  			val->intval = 0;
  	}
  
  	return 0;
  }

  static void  sbs_unit_adjustment(struct i2c_client *client,

  	enum power_supply_property psp, union power_supply_propval *val)
  {
  #define BASE_UNIT_CONVERSION		1000
  #define BATTERY_MODE_CAP_MULT_WATT	(10 * BASE_UNIT_CONVERSION)

  #define TIME_UNIT_CONVERSION		60
  #define TEMP_KELVIN_TO_CELSIUS		2731

  	switch (psp) {
  	case POWER_SUPPLY_PROP_ENERGY_NOW:
  	case POWER_SUPPLY_PROP_ENERGY_FULL:
  	case POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN:

  		/* sbs provides energy in units of 10mWh.

  		 * Convert to µWh
  		 */

  		val->intval *= BATTERY_MODE_CAP_MULT_WATT;
  		break;
  
  	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
  	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
  	case POWER_SUPPLY_PROP_CURRENT_NOW:

  	case POWER_SUPPLY_PROP_CHARGE_NOW:
  	case POWER_SUPPLY_PROP_CHARGE_FULL:
  	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:

  		val->intval *= BASE_UNIT_CONVERSION;
  		break;
  
  	case POWER_SUPPLY_PROP_TEMP:

  		/* sbs provides battery temperature in 0.1K

  		 * so convert it to 0.1°C
  		 */
  		val->intval -= TEMP_KELVIN_TO_CELSIUS;

  		break;
  
  	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG:
  	case POWER_SUPPLY_PROP_TIME_TO_FULL_AVG:

  		/* sbs provides time to empty and time to full in minutes.

  		 * Convert to seconds
  		 */

  		val->intval *= TIME_UNIT_CONVERSION;
  		break;
  
  	default:
  		dev_dbg(&client->dev,
  			"%s: no need for unit conversion %d
  ", __func__, psp);
  	}
  }

  static enum sbs_battery_mode sbs_set_battery_mode(struct i2c_client *client,
  	enum sbs_battery_mode mode)

  {
  	int ret, original_val;

  	original_val = sbs_read_word_data(client, BATTERY_MODE_OFFSET);

  	if (original_val < 0)
  		return original_val;
  
  	if ((original_val & BATTERY_MODE_MASK) == mode)
  		return mode;
  
  	if (mode == BATTERY_MODE_AMPS)
  		ret = original_val & ~BATTERY_MODE_MASK;
  	else
  		ret = original_val | BATTERY_MODE_MASK;

  	ret = sbs_write_word_data(client, BATTERY_MODE_OFFSET, ret);

  	if (ret < 0)
  		return ret;
  
  	return original_val & BATTERY_MODE_MASK;
  }

  static int sbs_get_battery_capacity(struct i2c_client *client,

  	int reg_offset, enum power_supply_property psp,

  	union power_supply_propval *val)
  {
  	s32 ret;

  	enum sbs_battery_mode mode = BATTERY_MODE_WATTS;

  
  	if (power_supply_is_amp_property(psp))
  		mode = BATTERY_MODE_AMPS;

  	mode = sbs_set_battery_mode(client, mode);

  	if (mode < 0)
  		return mode;

  	ret = sbs_read_word_data(client, sbs_data[reg_offset].addr);

  	if (ret < 0)
  		return ret;

  	if (psp == POWER_SUPPLY_PROP_CAPACITY) {

  		/* sbs spec says that this can be >100 %

  		* even if max value is 100 % */
  		val->intval = min(ret, 100);
  	} else
  		val->intval = ret;

  	ret = sbs_set_battery_mode(client, mode);

  	if (ret < 0)
  		return ret;

  	return 0;
  }

  static char sbs_serial[5];
  static int sbs_get_battery_serial_number(struct i2c_client *client,

  	union power_supply_propval *val)
  {
  	int ret;

  	ret = sbs_read_word_data(client, sbs_data[REG_SERIAL_NUMBER].addr);

  	if (ret < 0)
  		return ret;

  	ret = sprintf(sbs_serial, "%04x", ret);
  	val->strval = sbs_serial;

  
  	return 0;
  }

  static int sbs_get_property_index(struct i2c_client *client,

  	enum power_supply_property psp)
  {
  	int count;

  	for (count = 0; count < ARRAY_SIZE(sbs_data); count++)
  		if (psp == sbs_data[count].psp)

  			return count;
  
  	dev_warn(&client->dev,
  		"%s: Invalid Property - %d
  ", __func__, psp);
  
  	return -EINVAL;
  }

  static int sbs_get_property(struct power_supply *psy,

  	enum power_supply_property psp,
  	union power_supply_propval *val)
  {

  	int ret = 0;

  	struct sbs_info *chip = container_of(psy,
  				struct sbs_info, power_supply);
  	struct i2c_client *client = chip->client;

  
  	switch (psp) {
  	case POWER_SUPPLY_PROP_PRESENT:
  	case POWER_SUPPLY_PROP_HEALTH:

  		ret = sbs_get_battery_presence_and_health(client, psp, val);

  		if (psp == POWER_SUPPLY_PROP_PRESENT)
  			return 0;

  		break;
  
  	case POWER_SUPPLY_PROP_TECHNOLOGY:
  		val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
  		break;

  	case POWER_SUPPLY_PROP_ENERGY_NOW:
  	case POWER_SUPPLY_PROP_ENERGY_FULL:
  	case POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN:

  	case POWER_SUPPLY_PROP_CHARGE_NOW:
  	case POWER_SUPPLY_PROP_CHARGE_FULL:
  	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:

  	case POWER_SUPPLY_PROP_CAPACITY:

  		ret = sbs_get_property_index(client, psp);

  		if (ret < 0)
  			break;

  		ret = sbs_get_battery_capacity(client, ret, psp, val);

  		break;
  
  	case POWER_SUPPLY_PROP_SERIAL_NUMBER:

  		ret = sbs_get_battery_serial_number(client, val);

  		break;
  
  	case POWER_SUPPLY_PROP_STATUS:
  	case POWER_SUPPLY_PROP_CYCLE_COUNT:
  	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
  	case POWER_SUPPLY_PROP_CURRENT_NOW:
  	case POWER_SUPPLY_PROP_TEMP:
  	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG:
  	case POWER_SUPPLY_PROP_TIME_TO_FULL_AVG:

  	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:

  		ret = sbs_get_property_index(client, psp);

  		if (ret < 0)
  			break;

  		ret = sbs_get_battery_property(client, ret, psp, val);

  		break;
  
  	default:
  		dev_err(&client->dev,
  			"%s: INVALID property
  ", __func__);
  		return -EINVAL;
  	}

  	if (!chip->enable_detection)

  		goto done;

  	if (!chip->gpio_detect &&
  		chip->is_present != (ret >= 0)) {
  		chip->is_present = (ret >= 0);
  		power_supply_changed(&chip->power_supply);

  	}
  
  done:
  	if (!ret) {
  		/* Convert units to match requirements for power supply class */

  		sbs_unit_adjustment(client, psp, val);

  	}

  	dev_dbg(&client->dev,

  		"%s: property = %d, value = %x
  ", __func__, psp, val->intval);

  	if (ret && chip->is_present)

  		return ret;
  
  	/* battery not present, so return NODATA for properties */
  	if (ret)
  		return -ENODATA;

  	return 0;

  }

  static irqreturn_t sbs_irq(int irq, void *devid)

  {
  	struct power_supply *battery = devid;
  
  	power_supply_changed(battery);
  
  	return IRQ_HANDLED;
  }

  static void sbs_external_power_changed(struct power_supply *psy)

  {

  	struct sbs_info *chip;

  	chip = container_of(psy, struct sbs_info, power_supply);

  	if (chip->ignore_changes > 0) {
  		chip->ignore_changes--;

  		return;
  	}
  
  	/* cancel outstanding work */

  	cancel_delayed_work_sync(&chip->work);

  	schedule_delayed_work(&chip->work, HZ);
  	chip->poll_time = chip->pdata->poll_retry_count;

  }

  static void sbs_delayed_work(struct work_struct *work)

  {

  	struct sbs_info *chip;

  	s32 ret;

  	chip = container_of(work, struct sbs_info, work.work);

  	ret = sbs_read_word_data(chip->client, sbs_data[REG_STATUS].addr);

  	/* if the read failed, give up on this work */
  	if (ret < 0) {

  		chip->poll_time = 0;

  		return;
  	}
  
  	if (ret & BATTERY_FULL_CHARGED)
  		ret = POWER_SUPPLY_STATUS_FULL;
  	else if (ret & BATTERY_FULL_DISCHARGED)
  		ret = POWER_SUPPLY_STATUS_NOT_CHARGING;
  	else if (ret & BATTERY_DISCHARGING)
  		ret = POWER_SUPPLY_STATUS_DISCHARGING;
  	else
  		ret = POWER_SUPPLY_STATUS_CHARGING;

  	if (chip->last_state != ret) {
  		chip->poll_time = 0;
  		power_supply_changed(&chip->power_supply);

  		return;
  	}

  	if (chip->poll_time > 0) {
  		schedule_delayed_work(&chip->work, HZ);
  		chip->poll_time--;

  		return;
  	}
  }

  #if defined(CONFIG_OF)
  
  #include <linux/of_device.h>
  #include <linux/of_gpio.h>

  static const struct of_device_id sbs_dt_ids[] = {
  	{ .compatible = "sbs,sbs-battery" },

  	{ .compatible = "ti,bq20z75" },
  	{ }
  };

  MODULE_DEVICE_TABLE(of, sbs_dt_ids);

  static struct sbs_platform_data *sbs_of_populate_pdata(

  		struct i2c_client *client)
  {
  	struct device_node *of_node = client->dev.of_node;

  	struct sbs_platform_data *pdata = client->dev.platform_data;

  	enum of_gpio_flags gpio_flags;
  	int rc;
  	u32 prop;
  
  	/* verify this driver matches this device */
  	if (!of_node)
  		return NULL;
  
  	/* if platform data is set, honor it */
  	if (pdata)
  		return pdata;
  
  	/* first make sure at least one property is set, otherwise
  	 * it won't change behavior from running without pdata.
  	 */

  	if (!of_get_property(of_node, "sbs,i2c-retry-count", NULL) &&
  		!of_get_property(of_node, "sbs,poll-retry-count", NULL) &&
  		!of_get_property(of_node, "sbs,battery-detect-gpios", NULL))

  		goto of_out;

  	pdata = devm_kzalloc(&client->dev, sizeof(struct sbs_platform_data),

  				GFP_KERNEL);
  	if (!pdata)
  		goto of_out;

  	rc = of_property_read_u32(of_node, "sbs,i2c-retry-count", &prop);

  	if (!rc)
  		pdata->i2c_retry_count = prop;

  	rc = of_property_read_u32(of_node, "sbs,poll-retry-count", &prop);

  	if (!rc)
  		pdata->poll_retry_count = prop;

  	if (!of_get_property(of_node, "sbs,battery-detect-gpios", NULL)) {

  		pdata->battery_detect = -1;
  		goto of_out;
  	}
  
  	pdata->battery_detect = of_get_named_gpio_flags(of_node,

  			"sbs,battery-detect-gpios", 0, &gpio_flags);

  
  	if (gpio_flags & OF_GPIO_ACTIVE_LOW)
  		pdata->battery_detect_present = 0;
  	else
  		pdata->battery_detect_present = 1;
  
  of_out:
  	return pdata;
  }
  #else

  #define sbs_dt_ids NULL
  static struct sbs_platform_data *sbs_of_populate_pdata(

  	struct i2c_client *client)
  {
  	return client->dev.platform_data;
  }
  #endif

  static int __devinit sbs_probe(struct i2c_client *client,

  	const struct i2c_device_id *id)
  {

  	struct sbs_info *chip;
  	struct sbs_platform_data *pdata = client->dev.platform_data;

  	int rc;

  	int irq;

  	char *name;

  	name = kasprintf(GFP_KERNEL, "sbs-%s", dev_name(&client->dev));
  	if (!name) {
  		dev_err(&client->dev, "Failed to allocate device name
  ");

  		return -ENOMEM;

  	}
  
  	chip = kzalloc(sizeof(struct sbs_info), GFP_KERNEL);
  	if (!chip) {
  		rc = -ENOMEM;
  		goto exit_free_name;
  	}

  	chip->client = client;
  	chip->enable_detection = false;
  	chip->gpio_detect = false;

  	chip->power_supply.name = name;

  	chip->power_supply.type = POWER_SUPPLY_TYPE_BATTERY;
  	chip->power_supply.properties = sbs_properties;
  	chip->power_supply.num_properties = ARRAY_SIZE(sbs_properties);
  	chip->power_supply.get_property = sbs_get_property;

  	/* ignore first notification of external change, it is generated
  	 * from the power_supply_register call back
  	 */

  	chip->ignore_changes = 1;
  	chip->last_state = POWER_SUPPLY_STATUS_UNKNOWN;
  	chip->power_supply.external_power_changed = sbs_external_power_changed;

  	pdata = sbs_of_populate_pdata(client);

  	if (pdata) {

  		chip->gpio_detect = gpio_is_valid(pdata->battery_detect);
  		chip->pdata = pdata;

  	}

  	i2c_set_clientdata(client, chip);

  	if (!chip->gpio_detect)

  		goto skip_gpio;
  
  	rc = gpio_request(pdata->battery_detect, dev_name(&client->dev));
  	if (rc) {
  		dev_warn(&client->dev, "Failed to request gpio: %d
  ", rc);

  		chip->gpio_detect = false;

  		goto skip_gpio;
  	}
  
  	rc = gpio_direction_input(pdata->battery_detect);
  	if (rc) {
  		dev_warn(&client->dev, "Failed to get gpio as input: %d
  ", rc);
  		gpio_free(pdata->battery_detect);

  		chip->gpio_detect = false;

  		goto skip_gpio;
  	}
  
  	irq = gpio_to_irq(pdata->battery_detect);
  	if (irq <= 0) {
  		dev_warn(&client->dev, "Failed to get gpio as irq: %d
  ", irq);
  		gpio_free(pdata->battery_detect);

  		chip->gpio_detect = false;

  		goto skip_gpio;
  	}

  	rc = request_irq(irq, sbs_irq,

  		IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,

  		dev_name(&client->dev), &chip->power_supply);

  	if (rc) {
  		dev_warn(&client->dev, "Failed to request irq: %d
  ", rc);
  		gpio_free(pdata->battery_detect);

  		chip->gpio_detect = false;

  		goto skip_gpio;
  	}

  	chip->irq = irq;

  
  skip_gpio:

  	rc = power_supply_register(&client->dev, &chip->power_supply);

  	if (rc) {
  		dev_err(&client->dev,
  			"%s: Failed to register power supply
  ", __func__);

  		goto exit_psupply;

  	}
  
  	dev_info(&client->dev,
  		"%s: battery gas gauge device registered
  ", client->name);

  	INIT_DELAYED_WORK(&chip->work, sbs_delayed_work);

  	chip->enable_detection = true;

  	return 0;

  
  exit_psupply:

  	if (chip->irq)
  		free_irq(chip->irq, &chip->power_supply);
  	if (chip->gpio_detect)

  		gpio_free(pdata->battery_detect);

  	kfree(chip);

  exit_free_name:
  	kfree(name);

  	return rc;

  }

  static int __devexit sbs_remove(struct i2c_client *client)

  {

  	struct sbs_info *chip = i2c_get_clientdata(client);

  	if (chip->irq)
  		free_irq(chip->irq, &chip->power_supply);
  	if (chip->gpio_detect)
  		gpio_free(chip->pdata->battery_detect);

  	power_supply_unregister(&chip->power_supply);

  	cancel_delayed_work_sync(&chip->work);

  	kfree(chip->power_supply.name);

  	kfree(chip);
  	chip = NULL;

  
  	return 0;
  }
  
  #if defined CONFIG_PM

  static int sbs_suspend(struct i2c_client *client,

  	pm_message_t state)
  {

  	struct sbs_info *chip = i2c_get_clientdata(client);

  	s32 ret;

  	if (chip->poll_time > 0)
  		cancel_delayed_work_sync(&chip->work);

  	/* write to manufacturer access with sleep command */

  	ret = sbs_write_word_data(client, sbs_data[REG_MANUFACTURER_DATA].addr,

  		MANUFACTURER_ACCESS_SLEEP);

  	if (chip->is_present && ret < 0)

  		return ret;

  
  	return 0;
  }
  #else

  #define sbs_suspend		NULL

  #endif

  /* any smbus transaction will wake up sbs */
  #define sbs_resume		NULL

  static const struct i2c_device_id sbs_id[] = {

  	{ "bq20z75", 0 },

  	{ "sbs-battery", 1 },

  	{}
  };

  MODULE_DEVICE_TABLE(i2c, sbs_id);
  
  static struct i2c_driver sbs_battery_driver = {
  	.probe		= sbs_probe,
  	.remove		= __devexit_p(sbs_remove),
  	.suspend	= sbs_suspend,
  	.resume		= sbs_resume,
  	.id_table	= sbs_id,

  	.driver = {

  		.name	= "sbs-battery",
  		.of_match_table = sbs_dt_ids,

  	},
  };

  static int __init sbs_battery_init(void)

  {

  	return i2c_add_driver(&sbs_battery_driver);

  }

  module_init(sbs_battery_init);

  static void __exit sbs_battery_exit(void)

  {

  	i2c_del_driver(&sbs_battery_driver);

  }

  module_exit(sbs_battery_exit);

  MODULE_DESCRIPTION("SBS battery monitor driver");

  MODULE_LICENSE("GPL");