drivers/power/sbs-battery.c - kernel/msm-4.19 - Gitiles

 /*
  * 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, 0x0D, 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\n",
 			__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\n",
 			__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\n", __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\n", __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\n", __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\n", __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\n");
 		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\n", 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\n", 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\n", 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\n", 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\n", __func__);
 		goto exit_psupply;
 	}

 	dev_info(&client->dev,
 		"%s: battery gas gauge device registered\n", 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,
 	},
 };
 module_i2c_driver(sbs_battery_driver);

 MODULE_DESCRIPTION("SBS battery monitor driver");
 MODULE_LICENSE("GPL");
	/*
	* 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, 0x0D, 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\n",
	__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\n",
	__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\n", __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\n", __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\n", __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\n", __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\n");
	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\n", 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\n", 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\n", 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\n", 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\n", __func__);
	goto exit_psupply;
	}

	dev_info(&client->dev,
	"%s: battery gas gauge device registered\n", 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,
	},
	};
	module_i2c_driver(sbs_battery_driver);

	MODULE_DESCRIPTION("SBS battery monitor driver");
	MODULE_LICENSE("GPL");