drivers/power/bq20z75.c - pub/scm/linux/kernel/git/horms/ipvs-next - Git at Google

 /*
  * Gas Gauge driver for TI's BQ20Z75
  *
  * 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>

 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_FULL_CHARGE_CAPACITY,
 	REG_DESIGN_CAPACITY,
 	REG_DESIGN_VOLTAGE,
 };

 /* 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 BQ20Z75_DATA(_psp, _addr, _min_value, _max_value) { \
 	.psp = _psp, \
 	.addr = _addr, \
 	.min_value = _min_value, \
 	.max_value = _max_value, \
 }

 static const struct bq20z75_device_data {
 	enum power_supply_property psp;
 	u8 addr;
 	int min_value;
 	int max_value;
 } bq20z75_data[] = {
 	[REG_MANUFACTURER_DATA] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_PRESENT, 0x00, 0, 65535),
 	[REG_TEMPERATURE] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_TEMP, 0x08, 0, 65535),
 	[REG_VOLTAGE] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_VOLTAGE_NOW, 0x09, 0, 20000),
 	[REG_CURRENT] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_CURRENT_NOW, 0x0A, -32768,
 			32767),
 	[REG_CAPACITY] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_CAPACITY, 0x0E, 0, 100),
 	[REG_REMAINING_CAPACITY] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_ENERGY_NOW, 0x0F, 0, 65535),
 	[REG_FULL_CHARGE_CAPACITY] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_ENERGY_FULL, 0x10, 0, 65535),
 	[REG_TIME_TO_EMPTY] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG, 0x12, 0,
 			65535),
 	[REG_TIME_TO_FULL] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_TIME_TO_FULL_AVG, 0x13, 0,
 			65535),
 	[REG_STATUS] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_STATUS, 0x16, 0, 65535),
 	[REG_CYCLE_COUNT] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_CYCLE_COUNT, 0x17, 0, 65535),
 	[REG_DESIGN_CAPACITY] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN, 0x18, 0,
 			65535),
 	[REG_DESIGN_VOLTAGE] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN, 0x19, 0,
 			65535),
 	[REG_SERIAL_NUMBER] =
 		BQ20Z75_DATA(POWER_SUPPLY_PROP_SERIAL_NUMBER, 0x1C, 0, 65535),
 };

 static enum power_supply_property bq20z75_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,
 };

 struct bq20z75_info {
 	struct i2c_client	*client;
 	struct power_supply	power_supply;
 };

 static int bq20z75_read_word_data(struct i2c_client *client, u8 address)
 {
 	s32 ret;

 	ret = i2c_smbus_read_word_data(client, address);
 	if (ret < 0) {
 		dev_err(&client->dev,
 			"%s: i2c read at address 0x%x failed\n",
 			__func__, address);
 		return ret;
 	}
 	return le16_to_cpu(ret);
 }

 static int bq20z75_write_word_data(struct i2c_client *client, u8 address,
 	u16 value)
 {
 	s32 ret;

 	ret = i2c_smbus_write_word_data(client, address, le16_to_cpu(value));
 	if (ret < 0) {
 		dev_err(&client->dev,
 			"%s: i2c write to address 0x%x failed\n",
 			__func__, address);
 		return ret;
 	}
 	return 0;
 }

 static int bq20z75_get_battery_presence_and_health(
 	struct i2c_client *client, enum power_supply_property psp,
 	union power_supply_propval *val)
 {
 	s32 ret;

 	/* Write to ManufacturerAccess with
 	 * ManufacturerAccess command and then
 	 * read the status */
 	ret = bq20z75_write_word_data(client,
 		bq20z75_data[REG_MANUFACTURER_DATA].addr,
 		MANUFACTURER_ACCESS_STATUS);
 	if (ret < 0)
 		return ret;


 	ret = bq20z75_read_word_data(client,
 		bq20z75_data[REG_MANUFACTURER_DATA].addr);
 	if (ret < 0)
 		return ret;

 	if (ret < bq20z75_data[REG_MANUFACTURER_DATA].min_value ||
 	    ret > bq20z75_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 bq20z75_get_battery_property(struct i2c_client *client,
 	int reg_offset, enum power_supply_property psp,
 	union power_supply_propval *val)
 {
 	s32 ret;

 	ret = bq20z75_read_word_data(client,
 		bq20z75_data[reg_offset].addr);
 	if (ret < 0)
 		return ret;

 	/* returned values are 16 bit */
 	if (bq20z75_data[reg_offset].min_value < 0)
 		ret = (s16)ret;

 	if (ret >= bq20z75_data[reg_offset].min_value &&
 	    ret <= bq20z75_data[reg_offset].max_value) {
 		val->intval = ret;
 		if (psp == POWER_SUPPLY_PROP_STATUS) {
 			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;
 		}
 	} else {
 		if (psp == POWER_SUPPLY_PROP_STATUS)
 			val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
 		else
 			val->intval = 0;
 	}

 	return 0;
 }

 static void  bq20z75_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		600
 #define TEMP_KELVIN_TO_CELCIUS		2731
 	switch (psp) {
 	case POWER_SUPPLY_PROP_ENERGY_NOW:
 	case POWER_SUPPLY_PROP_ENERGY_FULL:
 	case POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN:
 		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:
 		val->intval *= BASE_UNIT_CONVERSION;
 		break;

 	case POWER_SUPPLY_PROP_TEMP:
 		/* bq20z75 provides battery tempreture in 0.1°K
 		 * so convert it to 0.1°C */
 		val->intval -= TEMP_KELVIN_TO_CELCIUS;
 		val->intval *= 10;
 		break;

 	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG:
 	case POWER_SUPPLY_PROP_TIME_TO_FULL_AVG:
 		val->intval *= TIME_UNIT_CONVERSION;
 		break;

 	default:
 		dev_dbg(&client->dev,
 			"%s: no need for unit conversion %d\n", __func__, psp);
 	}
 }

 static int bq20z75_get_battery_capacity(struct i2c_client *client,
 	int reg_offset, enum power_supply_property psp,
 	union power_supply_propval *val)
 {
 	s32 ret;

 	ret = bq20z75_read_word_data(client, bq20z75_data[reg_offset].addr);
 	if (ret < 0)
 		return ret;

 	if (psp == POWER_SUPPLY_PROP_CAPACITY) {
 		/* bq20z75 spec says that this can be >100 %
 		* even if max value is 100 % */
 		val->intval = min(ret, 100);
 	} else
 		val->intval = ret;

 	return 0;
 }

 static char bq20z75_serial[5];
 static int bq20z75_get_battery_serial_number(struct i2c_client *client,
 	union power_supply_propval *val)
 {
 	int ret;

 	ret = bq20z75_read_word_data(client,
 		bq20z75_data[REG_SERIAL_NUMBER].addr);
 	if (ret < 0)
 		return ret;

 	ret = sprintf(bq20z75_serial, "%04x", ret);
 	val->strval = bq20z75_serial;

 	return 0;
 }

 static int bq20z75_get_property(struct power_supply *psy,
 	enum power_supply_property psp,
 	union power_supply_propval *val)
 {
 	int count;
 	int ret;
 	struct bq20z75_info *bq20z75_device = container_of(psy,
 				struct bq20z75_info, power_supply);
 	struct i2c_client *client = bq20z75_device->client;

 	switch (psp) {
 	case POWER_SUPPLY_PROP_PRESENT:
 	case POWER_SUPPLY_PROP_HEALTH:
 		ret = bq20z75_get_battery_presence_and_health(client, psp, val);
 		if (ret)
 			return ret;
 		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_CAPACITY:
 		for (count = 0; count < ARRAY_SIZE(bq20z75_data); count++) {
 			if (psp == bq20z75_data[count].psp)
 				break;
 		}

 		ret = bq20z75_get_battery_capacity(client, count, psp, val);
 		if (ret)
 			return ret;

 		break;

 	case POWER_SUPPLY_PROP_SERIAL_NUMBER:
 		ret = bq20z75_get_battery_serial_number(client, val);
 		if (ret)
 			return ret;
 		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:
 		for (count = 0; count < ARRAY_SIZE(bq20z75_data); count++) {
 			if (psp == bq20z75_data[count].psp)
 				break;
 		}

 		ret = bq20z75_get_battery_property(client, count, psp, val);
 		if (ret)
 			return ret;

 		break;

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

 	/* Convert units to match requirements for power supply class */
 	bq20z75_unit_adjustment(client, psp, val);

 	dev_dbg(&client->dev,
 		"%s: property = %d, value = %d\n", __func__, psp, val->intval);

 	return 0;
 }

 static int bq20z75_probe(struct i2c_client *client,
 	const struct i2c_device_id *id)
 {
 	struct bq20z75_info *bq20z75_device;
 	int rc;

 	bq20z75_device = kzalloc(sizeof(struct bq20z75_info), GFP_KERNEL);
 	if (!bq20z75_device)
 		return -ENOMEM;

 	bq20z75_device->client = client;
 	bq20z75_device->power_supply.name = "battery";
 	bq20z75_device->power_supply.type = POWER_SUPPLY_TYPE_BATTERY;
 	bq20z75_device->power_supply.properties = bq20z75_properties;
 	bq20z75_device->power_supply.num_properties =
 		ARRAY_SIZE(bq20z75_properties);
 	bq20z75_device->power_supply.get_property = bq20z75_get_property;

 	i2c_set_clientdata(client, bq20z75_device);

 	rc = power_supply_register(&client->dev, &bq20z75_device->power_supply);
 	if (rc) {
 		dev_err(&client->dev,
 			"%s: Failed to register power supply\n", __func__);
 		kfree(bq20z75_device);
 		return rc;
 	}

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

 	return 0;
 }

 static int bq20z75_remove(struct i2c_client *client)
 {
 	struct bq20z75_info *bq20z75_device = i2c_get_clientdata(client);

 	power_supply_unregister(&bq20z75_device->power_supply);
 	kfree(bq20z75_device);
 	bq20z75_device = NULL;

 	return 0;
 }

 #if defined CONFIG_PM
 static int bq20z75_suspend(struct i2c_client *client,
 	pm_message_t state)
 {
 	s32 ret;

 	/* write to manufacturer access with sleep command */
 	ret = bq20z75_write_word_data(client,
 		bq20z75_data[REG_MANUFACTURER_DATA].addr,
 		MANUFACTURER_ACCESS_SLEEP);
 	if (ret < 0)
 		return ret;

 	return 0;
 }
 #else
 #define bq20z75_suspend		NULL
 #endif
 /* any smbus transaction will wake up bq20z75 */
 #define bq20z75_resume		NULL

 static const struct i2c_device_id bq20z75_id[] = {
 	{ "bq20z75", 0 },
 	{}
 };

 static struct i2c_driver bq20z75_battery_driver = {
 	.probe		= bq20z75_probe,
 	.remove		= bq20z75_remove,
 	.suspend	= bq20z75_suspend,
 	.resume		= bq20z75_resume,
 	.id_table	= bq20z75_id,
 	.driver = {
 		.name	= "bq20z75-battery",
 	},
 };

 static int __init bq20z75_battery_init(void)
 {
 	return i2c_add_driver(&bq20z75_battery_driver);
 }
 module_init(bq20z75_battery_init);

 static void __exit bq20z75_battery_exit(void)
 {
 	i2c_del_driver(&bq20z75_battery_driver);
 }
 module_exit(bq20z75_battery_exit);

 MODULE_DESCRIPTION("BQ20z75 battery monitor driver");
 MODULE_LICENSE("GPL");
	/*
	* Gas Gauge driver for TI's BQ20Z75
	*
	* 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>

	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_FULL_CHARGE_CAPACITY,
	REG_DESIGN_CAPACITY,
	REG_DESIGN_VOLTAGE,
	};

	/* 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 BQ20Z75_DATA(_psp, _addr, _min_value, _max_value) { \
	.psp = _psp, \
	.addr = _addr, \
	.min_value = _min_value, \
	.max_value = _max_value, \
	}

	static const struct bq20z75_device_data {
	enum power_supply_property psp;
	u8 addr;
	int min_value;
	int max_value;
	} bq20z75_data[] = {
	[REG_MANUFACTURER_DATA] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_PRESENT, 0x00, 0, 65535),
	[REG_TEMPERATURE] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_TEMP, 0x08, 0, 65535),
	[REG_VOLTAGE] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_VOLTAGE_NOW, 0x09, 0, 20000),
	[REG_CURRENT] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_CURRENT_NOW, 0x0A, -32768,
	32767),
	[REG_CAPACITY] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_CAPACITY, 0x0E, 0, 100),
	[REG_REMAINING_CAPACITY] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_ENERGY_NOW, 0x0F, 0, 65535),
	[REG_FULL_CHARGE_CAPACITY] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_ENERGY_FULL, 0x10, 0, 65535),
	[REG_TIME_TO_EMPTY] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG, 0x12, 0,
	65535),
	[REG_TIME_TO_FULL] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_TIME_TO_FULL_AVG, 0x13, 0,
	65535),
	[REG_STATUS] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_STATUS, 0x16, 0, 65535),
	[REG_CYCLE_COUNT] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_CYCLE_COUNT, 0x17, 0, 65535),
	[REG_DESIGN_CAPACITY] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN, 0x18, 0,
	65535),
	[REG_DESIGN_VOLTAGE] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN, 0x19, 0,
	65535),
	[REG_SERIAL_NUMBER] =
	BQ20Z75_DATA(POWER_SUPPLY_PROP_SERIAL_NUMBER, 0x1C, 0, 65535),
	};

	static enum power_supply_property bq20z75_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,
	};

	struct bq20z75_info {
	struct i2c_client *client;
	struct power_supply power_supply;
	};

	static int bq20z75_read_word_data(struct i2c_client *client, u8 address)
	{
	s32 ret;

	ret = i2c_smbus_read_word_data(client, address);
	if (ret < 0) {
	dev_err(&client->dev,
	"%s: i2c read at address 0x%x failed\n",
	__func__, address);
	return ret;
	}
	return le16_to_cpu(ret);
	}

	static int bq20z75_write_word_data(struct i2c_client *client, u8 address,
	u16 value)
	{
	s32 ret;

	ret = i2c_smbus_write_word_data(client, address, le16_to_cpu(value));
	if (ret < 0) {
	dev_err(&client->dev,
	"%s: i2c write to address 0x%x failed\n",
	__func__, address);
	return ret;
	}
	return 0;
	}

	static int bq20z75_get_battery_presence_and_health(
	struct i2c_client *client, enum power_supply_property psp,
	union power_supply_propval *val)
	{
	s32 ret;

	/* Write to ManufacturerAccess with
	* ManufacturerAccess command and then
	* read the status */
	ret = bq20z75_write_word_data(client,
	bq20z75_data[REG_MANUFACTURER_DATA].addr,
	MANUFACTURER_ACCESS_STATUS);
	if (ret < 0)
	return ret;


	ret = bq20z75_read_word_data(client,
	bq20z75_data[REG_MANUFACTURER_DATA].addr);
	if (ret < 0)
	return ret;

	if (ret < bq20z75_data[REG_MANUFACTURER_DATA].min_value \|\|
	ret > bq20z75_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 bq20z75_get_battery_property(struct i2c_client *client,
	int reg_offset, enum power_supply_property psp,
	union power_supply_propval *val)
	{
	s32 ret;

	ret = bq20z75_read_word_data(client,
	bq20z75_data[reg_offset].addr);
	if (ret < 0)
	return ret;

	/* returned values are 16 bit */
	if (bq20z75_data[reg_offset].min_value < 0)
	ret = (s16)ret;

	if (ret >= bq20z75_data[reg_offset].min_value &&
	ret <= bq20z75_data[reg_offset].max_value) {
	val->intval = ret;
	if (psp == POWER_SUPPLY_PROP_STATUS) {
	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;
	}
	} else {
	if (psp == POWER_SUPPLY_PROP_STATUS)
	val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
	else
	val->intval = 0;
	}

	return 0;
	}

	static void bq20z75_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 600
	#define TEMP_KELVIN_TO_CELCIUS 2731
	switch (psp) {
	case POWER_SUPPLY_PROP_ENERGY_NOW:
	case POWER_SUPPLY_PROP_ENERGY_FULL:
	case POWER_SUPPLY_PROP_ENERGY_FULL_DESIGN:
	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:
	val->intval *= BASE_UNIT_CONVERSION;
	break;

	case POWER_SUPPLY_PROP_TEMP:
	/* bq20z75 provides battery tempreture in 0.1°K
	* so convert it to 0.1°C */
	val->intval -= TEMP_KELVIN_TO_CELCIUS;
	val->intval *= 10;
	break;

	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG:
	case POWER_SUPPLY_PROP_TIME_TO_FULL_AVG:
	val->intval *= TIME_UNIT_CONVERSION;
	break;

	default:
	dev_dbg(&client->dev,
	"%s: no need for unit conversion %d\n", __func__, psp);
	}
	}

	static int bq20z75_get_battery_capacity(struct i2c_client *client,
	int reg_offset, enum power_supply_property psp,
	union power_supply_propval *val)
	{
	s32 ret;

	ret = bq20z75_read_word_data(client, bq20z75_data[reg_offset].addr);
	if (ret < 0)
	return ret;

	if (psp == POWER_SUPPLY_PROP_CAPACITY) {
	/* bq20z75 spec says that this can be >100 %
	* even if max value is 100 % */
	val->intval = min(ret, 100);
	} else
	val->intval = ret;

	return 0;
	}

	static char bq20z75_serial[5];
	static int bq20z75_get_battery_serial_number(struct i2c_client *client,
	union power_supply_propval *val)
	{
	int ret;

	ret = bq20z75_read_word_data(client,
	bq20z75_data[REG_SERIAL_NUMBER].addr);
	if (ret < 0)
	return ret;

	ret = sprintf(bq20z75_serial, "%04x", ret);
	val->strval = bq20z75_serial;

	return 0;
	}

	static int bq20z75_get_property(struct power_supply *psy,
	enum power_supply_property psp,
	union power_supply_propval *val)
	{
	int count;
	int ret;
	struct bq20z75_info *bq20z75_device = container_of(psy,
	struct bq20z75_info, power_supply);
	struct i2c_client *client = bq20z75_device->client;

	switch (psp) {
	case POWER_SUPPLY_PROP_PRESENT:
	case POWER_SUPPLY_PROP_HEALTH:
	ret = bq20z75_get_battery_presence_and_health(client, psp, val);
	if (ret)
	return ret;
	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_CAPACITY:
	for (count = 0; count < ARRAY_SIZE(bq20z75_data); count++) {
	if (psp == bq20z75_data[count].psp)
	break;
	}

	ret = bq20z75_get_battery_capacity(client, count, psp, val);
	if (ret)
	return ret;

	break;

	case POWER_SUPPLY_PROP_SERIAL_NUMBER:
	ret = bq20z75_get_battery_serial_number(client, val);
	if (ret)
	return ret;
	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:
	for (count = 0; count < ARRAY_SIZE(bq20z75_data); count++) {
	if (psp == bq20z75_data[count].psp)
	break;
	}

	ret = bq20z75_get_battery_property(client, count, psp, val);
	if (ret)
	return ret;

	break;

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

	/* Convert units to match requirements for power supply class */
	bq20z75_unit_adjustment(client, psp, val);

	dev_dbg(&client->dev,
	"%s: property = %d, value = %d\n", __func__, psp, val->intval);

	return 0;
	}

	static int bq20z75_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct bq20z75_info *bq20z75_device;
	int rc;

	bq20z75_device = kzalloc(sizeof(struct bq20z75_info), GFP_KERNEL);
	if (!bq20z75_device)
	return -ENOMEM;

	bq20z75_device->client = client;
	bq20z75_device->power_supply.name = "battery";
	bq20z75_device->power_supply.type = POWER_SUPPLY_TYPE_BATTERY;
	bq20z75_device->power_supply.properties = bq20z75_properties;
	bq20z75_device->power_supply.num_properties =
	ARRAY_SIZE(bq20z75_properties);
	bq20z75_device->power_supply.get_property = bq20z75_get_property;

	i2c_set_clientdata(client, bq20z75_device);

	rc = power_supply_register(&client->dev, &bq20z75_device->power_supply);
	if (rc) {
	dev_err(&client->dev,
	"%s: Failed to register power supply\n", __func__);
	kfree(bq20z75_device);
	return rc;
	}

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

	return 0;
	}

	static int bq20z75_remove(struct i2c_client *client)
	{
	struct bq20z75_info *bq20z75_device = i2c_get_clientdata(client);

	power_supply_unregister(&bq20z75_device->power_supply);
	kfree(bq20z75_device);
	bq20z75_device = NULL;

	return 0;
	}

	#if defined CONFIG_PM
	static int bq20z75_suspend(struct i2c_client *client,
	pm_message_t state)
	{
	s32 ret;

	/* write to manufacturer access with sleep command */
	ret = bq20z75_write_word_data(client,
	bq20z75_data[REG_MANUFACTURER_DATA].addr,
	MANUFACTURER_ACCESS_SLEEP);
	if (ret < 0)
	return ret;

	return 0;
	}
	#else
	#define bq20z75_suspend NULL
	#endif
	/* any smbus transaction will wake up bq20z75 */
	#define bq20z75_resume NULL

	static const struct i2c_device_id bq20z75_id[] = {
	{ "bq20z75", 0 },
	{}
	};

	static struct i2c_driver bq20z75_battery_driver = {
	.probe = bq20z75_probe,
	.remove = bq20z75_remove,
	.suspend = bq20z75_suspend,
	.resume = bq20z75_resume,
	.id_table = bq20z75_id,
	.driver = {
	.name = "bq20z75-battery",
	},
	};

	static int __init bq20z75_battery_init(void)
	{
	return i2c_add_driver(&bq20z75_battery_driver);
	}
	module_init(bq20z75_battery_init);

	static void __exit bq20z75_battery_exit(void)
	{
	i2c_del_driver(&bq20z75_battery_driver);
	}
	module_exit(bq20z75_battery_exit);

	MODULE_DESCRIPTION("BQ20z75 battery monitor driver");
	MODULE_LICENSE("GPL");