drivers/power/ltc2941-battery-gauge.c - kernel/quantenna - Git at Google

 /*
  * I2C client/driver for the Linear Technology LTC2941 and LTC2943
  * Battery Gas Gauge IC
  *
  * Copyright (C) 2014 Topic Embedded Systems
  *
  * Author: Auryn Verwegen
  * Author: Mike Looijmans
  */
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/types.h>
 #include <linux/errno.h>
 #include <linux/swab.h>
 #include <linux/i2c.h>
 #include <linux/delay.h>
 #include <linux/power_supply.h>
 #include <linux/slab.h>

 #define I16_MSB(x)			((x >> 8) & 0xFF)
 #define I16_LSB(x)			(x & 0xFF)

 #define LTC294X_WORK_DELAY		10	/* Update delay in seconds */

 #define LTC294X_MAX_VALUE		0xFFFF
 #define LTC294X_MID_SUPPLY		0x7FFF

 #define LTC2941_MAX_PRESCALER_EXP	7
 #define LTC2943_MAX_PRESCALER_EXP	6

 enum ltc294x_reg {
 	LTC294X_REG_STATUS		= 0x00,
 	LTC294X_REG_CONTROL		= 0x01,
 	LTC294X_REG_ACC_CHARGE_MSB	= 0x02,
 	LTC294X_REG_ACC_CHARGE_LSB	= 0x03,
 	LTC294X_REG_THRESH_HIGH_MSB	= 0x04,
 	LTC294X_REG_THRESH_HIGH_LSB	= 0x05,
 	LTC294X_REG_THRESH_LOW_MSB	= 0x06,
 	LTC294X_REG_THRESH_LOW_LSB	= 0x07,
 	LTC294X_REG_VOLTAGE_MSB	= 0x08,
 	LTC294X_REG_VOLTAGE_LSB	= 0x09,
 	LTC294X_REG_CURRENT_MSB	= 0x0E,
 	LTC294X_REG_CURRENT_LSB	= 0x0F,
 	LTC294X_REG_TEMPERATURE_MSB	= 0x14,
 	LTC294X_REG_TEMPERATURE_LSB	= 0x15,
 };

 #define LTC2943_REG_CONTROL_MODE_MASK (BIT(7) | BIT(6))
 #define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
 #define LTC294X_REG_CONTROL_PRESCALER_MASK	(BIT(5) | BIT(4) | BIT(3))
 #define LTC294X_REG_CONTROL_SHUTDOWN_MASK	(BIT(0))
 #define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
 	((x << 3) & LTC294X_REG_CONTROL_PRESCALER_MASK)
 #define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED	0

 #define LTC2941_NUM_REGS	0x08
 #define LTC2943_NUM_REGS	0x18

 struct ltc294x_info {
 	struct i2c_client *client;	/* I2C Client pointer */
 	struct power_supply *supply;	/* Supply pointer */
 	struct power_supply_desc supply_desc;	/* Supply description */
 	struct delayed_work work;	/* Work scheduler */
 	int num_regs;	/* Number of registers (chip type) */
 	int charge;	/* Last charge register content */
 	int r_sense;	/* mOhm */
 	int Qlsb;	/* nAh */
 };

 static inline int convert_bin_to_uAh(
 	const struct ltc294x_info *info, int Q)
 {
 	return ((Q * (info->Qlsb / 10))) / 100;
 }

 static inline int convert_uAh_to_bin(
 	const struct ltc294x_info *info, int uAh)
 {
 	int Q;

 	Q = (uAh * 100) / (info->Qlsb/10);
 	return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
 }

 static int ltc294x_read_regs(struct i2c_client *client,
 	enum ltc294x_reg reg, u8 *buf, int num_regs)
 {
 	int ret;
 	struct i2c_msg msgs[2] = { };
 	u8 reg_start = reg;

 	msgs[0].addr	= client->addr;
 	msgs[0].len	= 1;
 	msgs[0].buf	= &reg_start;

 	msgs[1].addr	= client->addr;
 	msgs[1].len	= num_regs;
 	msgs[1].buf	= buf;
 	msgs[1].flags	= I2C_M_RD;

 	ret = i2c_transfer(client->adapter, &msgs[0], 2);
 	if (ret < 0) {
 		dev_err(&client->dev, "ltc2941 read_reg failed!\n");
 		return ret;
 	}

 	dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
 		__func__, reg, num_regs, *buf);

 	return 0;
 }

 static int ltc294x_write_regs(struct i2c_client *client,
 	enum ltc294x_reg reg, const u8 *buf, int num_regs)
 {
 	int ret;
 	u8 reg_start = reg;

 	ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
 	if (ret < 0) {
 		dev_err(&client->dev, "ltc2941 write_reg failed!\n");
 		return ret;
 	}

 	dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
 		__func__, reg, num_regs, *buf);

 	return 0;
 }

 static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
 {
 	int ret;
 	u8 value;
 	u8 control;

 	/* Read status and control registers */
 	ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
 	if (ret < 0) {
 		dev_err(&info->client->dev,
 			"Could not read registers from device\n");
 		goto error_exit;
 	}

 	control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
 				LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
 	/* Put the 2943 into "monitor" mode, so it measures every 10 sec */
 	if (info->num_regs == LTC2943_NUM_REGS)
 		control |= LTC2943_REG_CONTROL_MODE_SCAN;

 	if (value != control) {
 		ret = ltc294x_write_regs(info->client,
 			LTC294X_REG_CONTROL, &control, 1);
 		if (ret < 0) {
 			dev_err(&info->client->dev,
 				"Could not write register\n");
 			goto error_exit;
 		}
 	}

 	return 0;

 error_exit:
 	return ret;
 }

 static int ltc294x_read_charge_register(const struct ltc294x_info *info)
 {
 	int ret;
 	u8 datar[2];

 	ret = ltc294x_read_regs(info->client,
 		LTC294X_REG_ACC_CHARGE_MSB, &datar[0], 2);
 	if (ret < 0)
 		return ret;
 	return (datar[0] << 8) + datar[1];
 }

 static int ltc294x_get_charge_now(const struct ltc294x_info *info, int *val)
 {
 	int value = ltc294x_read_charge_register(info);

 	if (value < 0)
 		return value;
 	/* When r_sense < 0, this counts up when the battery discharges */
 	if (info->Qlsb < 0)
 		value -= 0xFFFF;
 	*val = convert_bin_to_uAh(info, value);
 	return 0;
 }

 static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
 {
 	int ret;
 	u8 dataw[2];
 	u8 ctrl_reg;
 	s32 value;

 	value = convert_uAh_to_bin(info, val);
 	/* Direction depends on how sense+/- were connected */
 	if (info->Qlsb < 0)
 		value += 0xFFFF;
 	if ((value < 0) || (value > 0xFFFF)) /* input validation */
 		return -EINVAL;

 	/* Read control register */
 	ret = ltc294x_read_regs(info->client,
 		LTC294X_REG_CONTROL, &ctrl_reg, 1);
 	if (ret < 0)
 		return ret;
 	/* Disable analog section */
 	ctrl_reg |= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
 	ret = ltc294x_write_regs(info->client,
 		LTC294X_REG_CONTROL, &ctrl_reg, 1);
 	if (ret < 0)
 		return ret;
 	/* Set new charge value */
 	dataw[0] = I16_MSB(value);
 	dataw[1] = I16_LSB(value);
 	ret = ltc294x_write_regs(info->client,
 		LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
 	if (ret < 0)
 		goto error_exit;
 	/* Enable analog section */
 error_exit:
 	ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
 	ret = ltc294x_write_regs(info->client,
 		LTC294X_REG_CONTROL, &ctrl_reg, 1);

 	return ret < 0 ? ret : 0;
 }

 static int ltc294x_get_charge_counter(
 	const struct ltc294x_info *info, int *val)
 {
 	int value = ltc294x_read_charge_register(info);

 	if (value < 0)
 		return value;
 	value -= LTC294X_MID_SUPPLY;
 	*val = convert_bin_to_uAh(info, value);
 	return 0;
 }

 static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
 {
 	int ret;
 	u8 datar[2];
 	u32 value;

 	ret = ltc294x_read_regs(info->client,
 		LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
 	value = (datar[0] << 8) | datar[1];
 	*val = ((value * 23600) / 0xFFFF) * 1000; /* in uV */
 	return ret;
 }

 static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
 {
 	int ret;
 	u8 datar[2];
 	s32 value;

 	ret = ltc294x_read_regs(info->client,
 		LTC294X_REG_CURRENT_MSB, &datar[0], 2);
 	value = (datar[0] << 8) | datar[1];
 	value -= 0x7FFF;
 	/* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
 	 * the formula below keeps everything in s32 range while preserving
 	 * enough digits */
 	*val = 1000 * ((60000 * value) / (info->r_sense * 0x7FFF)); /* in uA */
 	return ret;
 }

 static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
 {
 	int ret;
 	u8 datar[2];
 	u32 value;

 	ret = ltc294x_read_regs(info->client,
 		LTC294X_REG_TEMPERATURE_MSB, &datar[0], 2);
 	value = (datar[0] << 8) | datar[1];
 	/* Full-scale is 510 Kelvin, convert to centidegrees  */
 	*val = (((51000 * value) / 0xFFFF) - 27215);
 	return ret;
 }

 static int ltc294x_get_property(struct power_supply *psy,
 				enum power_supply_property prop,
 				union power_supply_propval *val)
 {
 	struct ltc294x_info *info = power_supply_get_drvdata(psy);

 	switch (prop) {
 	case POWER_SUPPLY_PROP_CHARGE_NOW:
 		return ltc294x_get_charge_now(info, &val->intval);
 	case POWER_SUPPLY_PROP_CHARGE_COUNTER:
 		return ltc294x_get_charge_counter(info, &val->intval);
 	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
 		return ltc294x_get_voltage(info, &val->intval);
 	case POWER_SUPPLY_PROP_CURRENT_NOW:
 		return ltc294x_get_current(info, &val->intval);
 	case POWER_SUPPLY_PROP_TEMP:
 		return ltc294x_get_temperature(info, &val->intval);
 	default:
 		return -EINVAL;
 	}
 }

 static int ltc294x_set_property(struct power_supply *psy,
 	enum power_supply_property psp,
 	const union power_supply_propval *val)
 {
 	struct ltc294x_info *info = power_supply_get_drvdata(psy);

 	switch (psp) {
 	case POWER_SUPPLY_PROP_CHARGE_NOW:
 		return ltc294x_set_charge_now(info, val->intval);
 	default:
 		return -EPERM;
 	}
 }

 static int ltc294x_property_is_writeable(
 	struct power_supply *psy, enum power_supply_property psp)
 {
 	switch (psp) {
 	case POWER_SUPPLY_PROP_CHARGE_NOW:
 		return 1;
 	default:
 		return 0;
 	}
 }

 static void ltc294x_update(struct ltc294x_info *info)
 {
 	int charge = ltc294x_read_charge_register(info);

 	if (charge != info->charge) {
 		info->charge = charge;
 		power_supply_changed(info->supply);
 	}
 }

 static void ltc294x_work(struct work_struct *work)
 {
 	struct ltc294x_info *info;

 	info = container_of(work, struct ltc294x_info, work.work);
 	ltc294x_update(info);
 	schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 }

 static enum power_supply_property ltc294x_properties[] = {
 	POWER_SUPPLY_PROP_CHARGE_COUNTER,
 	POWER_SUPPLY_PROP_CHARGE_NOW,
 	POWER_SUPPLY_PROP_VOLTAGE_NOW,
 	POWER_SUPPLY_PROP_CURRENT_NOW,
 	POWER_SUPPLY_PROP_TEMP,
 };

 static int ltc294x_i2c_remove(struct i2c_client *client)
 {
 	struct ltc294x_info *info = i2c_get_clientdata(client);

 	cancel_delayed_work(&info->work);
 	power_supply_unregister(info->supply);
 	return 0;
 }

 static int ltc294x_i2c_probe(struct i2c_client *client,
 	const struct i2c_device_id *id)
 {
 	struct power_supply_config psy_cfg = {};
 	struct ltc294x_info *info;
 	int ret;
 	u32 prescaler_exp;
 	s32 r_sense;
 	struct device_node *np;

 	info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
 	if (info == NULL)
 		return -ENOMEM;

 	i2c_set_clientdata(client, info);

 	np = of_node_get(client->dev.of_node);

 	info->num_regs = id->driver_data;
 	info->supply_desc.name = np->name;

 	/* r_sense can be negative, when sense+ is connected to the battery
 	 * instead of the sense-. This results in reversed measurements. */
 	ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
 	if (ret < 0) {
 		dev_err(&client->dev,
 			"Could not find lltc,resistor-sense in devicetree\n");
 		return ret;
 	}
 	info->r_sense = r_sense;

 	ret = of_property_read_u32(np, "lltc,prescaler-exponent",
 		&prescaler_exp);
 	if (ret < 0) {
 		dev_warn(&client->dev,
 			"lltc,prescaler-exponent not in devicetree\n");
 		prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
 	}

 	if (info->num_regs == LTC2943_NUM_REGS) {
 		if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
 			prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
 		info->Qlsb = ((340 * 50000) / r_sense) /
 				(4096 / (1 << (2*prescaler_exp)));
 	} else {
 		if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
 			prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
 		info->Qlsb = ((85 * 50000) / r_sense) /
 				(128 / (1 << prescaler_exp));
 	}

 	info->client = client;
 	info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
 	info->supply_desc.properties = ltc294x_properties;
 	if (info->num_regs >= LTC294X_REG_TEMPERATURE_LSB)
 		info->supply_desc.num_properties =
 			ARRAY_SIZE(ltc294x_properties);
 	else if (info->num_regs >= LTC294X_REG_CURRENT_LSB)
 		info->supply_desc.num_properties =
 			ARRAY_SIZE(ltc294x_properties) - 1;
 	else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
 		info->supply_desc.num_properties =
 			ARRAY_SIZE(ltc294x_properties) - 2;
 	else
 		info->supply_desc.num_properties =
 			ARRAY_SIZE(ltc294x_properties) - 3;
 	info->supply_desc.get_property = ltc294x_get_property;
 	info->supply_desc.set_property = ltc294x_set_property;
 	info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
 	info->supply_desc.external_power_changed	= NULL;

 	psy_cfg.drv_data = info;

 	INIT_DELAYED_WORK(&info->work, ltc294x_work);

 	ret = ltc294x_reset(info, prescaler_exp);
 	if (ret < 0) {
 		dev_err(&client->dev, "Communication with chip failed\n");
 		return ret;
 	}

 	info->supply = power_supply_register(&client->dev, &info->supply_desc,
 					     &psy_cfg);
 	if (IS_ERR(info->supply)) {
 		dev_err(&client->dev, "failed to register ltc2941\n");
 		return PTR_ERR(info->supply);
 	} else {
 		schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 	}

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP

 static int ltc294x_suspend(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct ltc294x_info *info = i2c_get_clientdata(client);

 	cancel_delayed_work(&info->work);
 	return 0;
 }

 static int ltc294x_resume(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct ltc294x_info *info = i2c_get_clientdata(client);

 	schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 	return 0;
 }

 static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
 #define LTC294X_PM_OPS (&ltc294x_pm_ops)

 #else
 #define LTC294X_PM_OPS NULL
 #endif /* CONFIG_PM_SLEEP */


 static const struct i2c_device_id ltc294x_i2c_id[] = {
 	{"ltc2941", LTC2941_NUM_REGS},
 	{"ltc2943", LTC2943_NUM_REGS},
 	{ },
 };
 MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);

 static struct i2c_driver ltc294x_driver = {
 	.driver = {
 		.name	= "LTC2941",
 		.pm	= LTC294X_PM_OPS,
 	},
 	.probe		= ltc294x_i2c_probe,
 	.remove		= ltc294x_i2c_remove,
 	.id_table	= ltc294x_i2c_id,
 };
 module_i2c_driver(ltc294x_driver);

 MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
 MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
 MODULE_DESCRIPTION("LTC2941/LTC2943 Battery Gas Gauge IC driver");
 MODULE_LICENSE("GPL");
	/*
	* I2C client/driver for the Linear Technology LTC2941 and LTC2943
	* Battery Gas Gauge IC
	*
	* Copyright (C) 2014 Topic Embedded Systems
	*
	* Author: Auryn Verwegen
	* Author: Mike Looijmans
	*/
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/types.h>
	#include <linux/errno.h>
	#include <linux/swab.h>
	#include <linux/i2c.h>
	#include <linux/delay.h>
	#include <linux/power_supply.h>
	#include <linux/slab.h>

	#define I16_MSB(x) ((x >> 8) & 0xFF)
	#define I16_LSB(x) (x & 0xFF)

	#define LTC294X_WORK_DELAY 10 /* Update delay in seconds */

	#define LTC294X_MAX_VALUE 0xFFFF
	#define LTC294X_MID_SUPPLY 0x7FFF

	#define LTC2941_MAX_PRESCALER_EXP 7
	#define LTC2943_MAX_PRESCALER_EXP 6

	enum ltc294x_reg {
	LTC294X_REG_STATUS = 0x00,
	LTC294X_REG_CONTROL = 0x01,
	LTC294X_REG_ACC_CHARGE_MSB = 0x02,
	LTC294X_REG_ACC_CHARGE_LSB = 0x03,
	LTC294X_REG_THRESH_HIGH_MSB = 0x04,
	LTC294X_REG_THRESH_HIGH_LSB = 0x05,
	LTC294X_REG_THRESH_LOW_MSB = 0x06,
	LTC294X_REG_THRESH_LOW_LSB = 0x07,
	LTC294X_REG_VOLTAGE_MSB = 0x08,
	LTC294X_REG_VOLTAGE_LSB = 0x09,
	LTC294X_REG_CURRENT_MSB = 0x0E,
	LTC294X_REG_CURRENT_LSB = 0x0F,
	LTC294X_REG_TEMPERATURE_MSB = 0x14,
	LTC294X_REG_TEMPERATURE_LSB = 0x15,
	};

	#define LTC2943_REG_CONTROL_MODE_MASK (BIT(7) \| BIT(6))
	#define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
	#define LTC294X_REG_CONTROL_PRESCALER_MASK (BIT(5) \| BIT(4) \| BIT(3))
	#define LTC294X_REG_CONTROL_SHUTDOWN_MASK (BIT(0))
	#define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
	((x << 3) & LTC294X_REG_CONTROL_PRESCALER_MASK)
	#define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED 0

	#define LTC2941_NUM_REGS 0x08
	#define LTC2943_NUM_REGS 0x18

	struct ltc294x_info {
	struct i2c_client client; / I2C Client pointer */
	struct power_supply supply; / Supply pointer */
	struct power_supply_desc supply_desc; /* Supply description */
	struct delayed_work work; /* Work scheduler */
	int num_regs; /* Number of registers (chip type) */
	int charge; /* Last charge register content */
	int r_sense; /* mOhm */
	int Qlsb; /* nAh */
	};

	static inline int convert_bin_to_uAh(
	const struct ltc294x_info *info, int Q)
	{
	return ((Q * (info->Qlsb / 10))) / 100;
	}

	static inline int convert_uAh_to_bin(
	const struct ltc294x_info *info, int uAh)
	{
	int Q;

	Q = (uAh * 100) / (info->Qlsb/10);
	return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
	}

	static int ltc294x_read_regs(struct i2c_client *client,
	enum ltc294x_reg reg, u8 *buf, int num_regs)
	{
	int ret;
	struct i2c_msg msgs[2] = { };
	u8 reg_start = reg;

	msgs[0].addr = client->addr;
	msgs[0].len = 1;
	msgs[0].buf = &reg_start;

	msgs[1].addr = client->addr;
	msgs[1].len = num_regs;
	msgs[1].buf = buf;
	msgs[1].flags = I2C_M_RD;

	ret = i2c_transfer(client->adapter, &msgs[0], 2);
	if (ret < 0) {
	dev_err(&client->dev, "ltc2941 read_reg failed!\n");
	return ret;
	}

	dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
	__func__, reg, num_regs, *buf);

	return 0;
	}

	static int ltc294x_write_regs(struct i2c_client *client,
	enum ltc294x_reg reg, const u8 *buf, int num_regs)
	{
	int ret;
	u8 reg_start = reg;

	ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
	if (ret < 0) {
	dev_err(&client->dev, "ltc2941 write_reg failed!\n");
	return ret;
	}

	dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
	__func__, reg, num_regs, *buf);

	return 0;
	}

	static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
	{
	int ret;
	u8 value;
	u8 control;

	/* Read status and control registers */
	ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
	if (ret < 0) {
	dev_err(&info->client->dev,
	"Could not read registers from device\n");
	goto error_exit;
	}

	control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) \|
	LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
	/* Put the 2943 into "monitor" mode, so it measures every 10 sec */
	if (info->num_regs == LTC2943_NUM_REGS)
	control \|= LTC2943_REG_CONTROL_MODE_SCAN;

	if (value != control) {
	ret = ltc294x_write_regs(info->client,
	LTC294X_REG_CONTROL, &control, 1);
	if (ret < 0) {
	dev_err(&info->client->dev,
	"Could not write register\n");
	goto error_exit;
	}
	}

	return 0;

	error_exit:
	return ret;
	}

	static int ltc294x_read_charge_register(const struct ltc294x_info *info)
	{
	int ret;
	u8 datar[2];

	ret = ltc294x_read_regs(info->client,
	LTC294X_REG_ACC_CHARGE_MSB, &datar[0], 2);
	if (ret < 0)
	return ret;
	return (datar[0] << 8) + datar[1];
	}

	static int ltc294x_get_charge_now(const struct ltc294x_info info, int val)
	{
	int value = ltc294x_read_charge_register(info);

	if (value < 0)
	return value;
	/* When r_sense < 0, this counts up when the battery discharges */
	if (info->Qlsb < 0)
	value -= 0xFFFF;
	*val = convert_bin_to_uAh(info, value);
	return 0;
	}

	static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
	{
	int ret;
	u8 dataw[2];
	u8 ctrl_reg;
	s32 value;

	value = convert_uAh_to_bin(info, val);
	/* Direction depends on how sense+/- were connected */
	if (info->Qlsb < 0)
	value += 0xFFFF;
	if ((value < 0) \|\| (value > 0xFFFF)) /* input validation */
	return -EINVAL;

	/* Read control register */
	ret = ltc294x_read_regs(info->client,
	LTC294X_REG_CONTROL, &ctrl_reg, 1);
	if (ret < 0)
	return ret;
	/* Disable analog section */
	ctrl_reg \|= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
	ret = ltc294x_write_regs(info->client,
	LTC294X_REG_CONTROL, &ctrl_reg, 1);
	if (ret < 0)
	return ret;
	/* Set new charge value */
	dataw[0] = I16_MSB(value);
	dataw[1] = I16_LSB(value);
	ret = ltc294x_write_regs(info->client,
	LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
	if (ret < 0)
	goto error_exit;
	/* Enable analog section */
	error_exit:
	ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
	ret = ltc294x_write_regs(info->client,
	LTC294X_REG_CONTROL, &ctrl_reg, 1);

	return ret < 0 ? ret : 0;
	}

	static int ltc294x_get_charge_counter(
	const struct ltc294x_info info, int val)
	{
	int value = ltc294x_read_charge_register(info);

	if (value < 0)
	return value;
	value -= LTC294X_MID_SUPPLY;
	*val = convert_bin_to_uAh(info, value);
	return 0;
	}

	static int ltc294x_get_voltage(const struct ltc294x_info info, int val)
	{
	int ret;
	u8 datar[2];
	u32 value;

	ret = ltc294x_read_regs(info->client,
	LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
	value = (datar[0] << 8) \| datar[1];
	val = ((value 23600) / 0xFFFF) * 1000; /* in uV */
	return ret;
	}

	static int ltc294x_get_current(const struct ltc294x_info info, int val)
	{
	int ret;
	u8 datar[2];
	s32 value;

	ret = ltc294x_read_regs(info->client,
	LTC294X_REG_CURRENT_MSB, &datar[0], 2);
	value = (datar[0] << 8) \| datar[1];
	value -= 0x7FFF;
	/* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
	* the formula below keeps everything in s32 range while preserving
	* enough digits */
	val = 1000 ((60000 * value) / (info->r_sense * 0x7FFF)); /* in uA */
	return ret;
	}

	static int ltc294x_get_temperature(const struct ltc294x_info info, int val)
	{
	int ret;
	u8 datar[2];
	u32 value;

	ret = ltc294x_read_regs(info->client,
	LTC294X_REG_TEMPERATURE_MSB, &datar[0], 2);
	value = (datar[0] << 8) \| datar[1];
	/* Full-scale is 510 Kelvin, convert to centidegrees */
	val = (((51000 value) / 0xFFFF) - 27215);
	return ret;
	}

	static int ltc294x_get_property(struct power_supply *psy,
	enum power_supply_property prop,
	union power_supply_propval *val)
	{
	struct ltc294x_info *info = power_supply_get_drvdata(psy);

	switch (prop) {
	case POWER_SUPPLY_PROP_CHARGE_NOW:
	return ltc294x_get_charge_now(info, &val->intval);
	case POWER_SUPPLY_PROP_CHARGE_COUNTER:
	return ltc294x_get_charge_counter(info, &val->intval);
	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
	return ltc294x_get_voltage(info, &val->intval);
	case POWER_SUPPLY_PROP_CURRENT_NOW:
	return ltc294x_get_current(info, &val->intval);
	case POWER_SUPPLY_PROP_TEMP:
	return ltc294x_get_temperature(info, &val->intval);
	default:
	return -EINVAL;
	}
	}

	static int ltc294x_set_property(struct power_supply *psy,
	enum power_supply_property psp,
	const union power_supply_propval *val)
	{
	struct ltc294x_info *info = power_supply_get_drvdata(psy);

	switch (psp) {
	case POWER_SUPPLY_PROP_CHARGE_NOW:
	return ltc294x_set_charge_now(info, val->intval);
	default:
	return -EPERM;
	}
	}

	static int ltc294x_property_is_writeable(
	struct power_supply *psy, enum power_supply_property psp)
	{
	switch (psp) {
	case POWER_SUPPLY_PROP_CHARGE_NOW:
	return 1;
	default:
	return 0;
	}
	}

	static void ltc294x_update(struct ltc294x_info *info)
	{
	int charge = ltc294x_read_charge_register(info);

	if (charge != info->charge) {
	info->charge = charge;
	power_supply_changed(info->supply);
	}
	}

	static void ltc294x_work(struct work_struct *work)
	{
	struct ltc294x_info *info;

	info = container_of(work, struct ltc294x_info, work.work);
	ltc294x_update(info);
	schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
	}

	static enum power_supply_property ltc294x_properties[] = {
	POWER_SUPPLY_PROP_CHARGE_COUNTER,
	POWER_SUPPLY_PROP_CHARGE_NOW,
	POWER_SUPPLY_PROP_VOLTAGE_NOW,
	POWER_SUPPLY_PROP_CURRENT_NOW,
	POWER_SUPPLY_PROP_TEMP,
	};

	static int ltc294x_i2c_remove(struct i2c_client *client)
	{
	struct ltc294x_info *info = i2c_get_clientdata(client);

	cancel_delayed_work(&info->work);
	power_supply_unregister(info->supply);
	return 0;
	}

	static int ltc294x_i2c_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct power_supply_config psy_cfg = {};
	struct ltc294x_info *info;
	int ret;
	u32 prescaler_exp;
	s32 r_sense;
	struct device_node *np;

	info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
	if (info == NULL)
	return -ENOMEM;

	i2c_set_clientdata(client, info);

	np = of_node_get(client->dev.of_node);

	info->num_regs = id->driver_data;
	info->supply_desc.name = np->name;

	/* r_sense can be negative, when sense+ is connected to the battery
	* instead of the sense-. This results in reversed measurements. */
	ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
	if (ret < 0) {
	dev_err(&client->dev,
	"Could not find lltc,resistor-sense in devicetree\n");
	return ret;
	}
	info->r_sense = r_sense;

	ret = of_property_read_u32(np, "lltc,prescaler-exponent",
	&prescaler_exp);
	if (ret < 0) {
	dev_warn(&client->dev,
	"lltc,prescaler-exponent not in devicetree\n");
	prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
	}

	if (info->num_regs == LTC2943_NUM_REGS) {
	if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
	prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
	info->Qlsb = ((340 * 50000) / r_sense) /
	(4096 / (1 << (2*prescaler_exp)));
	} else {
	if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
	prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
	info->Qlsb = ((85 * 50000) / r_sense) /
	(128 / (1 << prescaler_exp));
	}

	info->client = client;
	info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
	info->supply_desc.properties = ltc294x_properties;
	if (info->num_regs >= LTC294X_REG_TEMPERATURE_LSB)
	info->supply_desc.num_properties =
	ARRAY_SIZE(ltc294x_properties);
	else if (info->num_regs >= LTC294X_REG_CURRENT_LSB)
	info->supply_desc.num_properties =
	ARRAY_SIZE(ltc294x_properties) - 1;
	else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
	info->supply_desc.num_properties =
	ARRAY_SIZE(ltc294x_properties) - 2;
	else
	info->supply_desc.num_properties =
	ARRAY_SIZE(ltc294x_properties) - 3;
	info->supply_desc.get_property = ltc294x_get_property;
	info->supply_desc.set_property = ltc294x_set_property;
	info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
	info->supply_desc.external_power_changed = NULL;

	psy_cfg.drv_data = info;

	INIT_DELAYED_WORK(&info->work, ltc294x_work);

	ret = ltc294x_reset(info, prescaler_exp);
	if (ret < 0) {
	dev_err(&client->dev, "Communication with chip failed\n");
	return ret;
	}

	info->supply = power_supply_register(&client->dev, &info->supply_desc,
	&psy_cfg);
	if (IS_ERR(info->supply)) {
	dev_err(&client->dev, "failed to register ltc2941\n");
	return PTR_ERR(info->supply);
	} else {
	schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
	}

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP

	static int ltc294x_suspend(struct device *dev)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct ltc294x_info *info = i2c_get_clientdata(client);

	cancel_delayed_work(&info->work);
	return 0;
	}

	static int ltc294x_resume(struct device *dev)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct ltc294x_info *info = i2c_get_clientdata(client);

	schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
	return 0;
	}

	static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
	#define LTC294X_PM_OPS (&ltc294x_pm_ops)

	#else
	#define LTC294X_PM_OPS NULL
	#endif /* CONFIG_PM_SLEEP */


	static const struct i2c_device_id ltc294x_i2c_id[] = {
	{"ltc2941", LTC2941_NUM_REGS},
	{"ltc2943", LTC2943_NUM_REGS},
	{ },
	};
	MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);

	static struct i2c_driver ltc294x_driver = {
	.driver = {
	.name = "LTC2941",
	.pm = LTC294X_PM_OPS,
	},
	.probe = ltc294x_i2c_probe,
	.remove = ltc294x_i2c_remove,
	.id_table = ltc294x_i2c_id,
	};
	module_i2c_driver(ltc294x_driver);

	MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
	MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
	MODULE_DESCRIPTION("LTC2941/LTC2943 Battery Gas Gauge IC driver");
	MODULE_LICENSE("GPL");