Commit 085bc24d authored by Mike Looijmans's avatar Mike Looijmans Committed by Sebastian Reichel
Browse files

Add LTC2941/LTC2943 Battery Gauge Driver 



Both the LTC2941 and LTC2943 measure battery capacity.
The LTC2943 is compatible with the LTC2941, it adds voltage and
temperature monitoring, and uses a slightly different conversion
formula for the charge counter.

To avoid confusion with e.g. the LTC2945, the driver is called
LTC2941 instead of LTC294X.

v2: Fix units of measurement: uV, uA and centidegrees.
v3: Correctly set configuration register. Allow negative values
    for the sense resistor.
v4: Run checkpatch.pl and fix all errors and warnings.
v5: Prefix "lltc," to devicetree properties.

Signed-off-by: default avatarMike Looijmans <mike.looijmans@topic.nl>
[ removed .owner field ]
Signed-off-by: default avatarSebastian Reichel <sre@kernel.org>
parent 79969f6a

drivers/power/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -388,6 +388,14 @@ config CHARGER_TPS65090 
	 Say Y here to enable support for battery charging with TPS65090

	 PMIC chips.



config BATTERY_GAUGE_LTC2941

	tristate "LTC2941/LTC2943 Battery Gauge Driver"

	depends on I2C

	help

	  Say Y here to include support for LTC2941 and LTC2943 Battery

	  Gauge IC. The driver reports the charge count continuously, and

	  measures the voltage and temperature every 10 seconds.



config AB8500_BM

	bool "AB8500 Battery Management Driver"

	depends on AB8500_CORE && AB8500_GPADC

drivers/power/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ obj-$(CONFIG_BATTERY_DS2760) += ds2760_battery.o 
obj-$(CONFIG_BATTERY_DS2780)	+= ds2780_battery.o

obj-$(CONFIG_BATTERY_DS2781)	+= ds2781_battery.o

obj-$(CONFIG_BATTERY_DS2782)	+= ds2782_battery.o

obj-$(CONFIG_BATTERY_GAUGE_LTC2941)	+= ltc2941-battery-gauge.o

obj-$(CONFIG_BATTERY_GOLDFISH)	+= goldfish_battery.o

obj-$(CONFIG_BATTERY_PMU)	+= pmu_battery.o

obj-$(CONFIG_BATTERY_OLPC)	+= olpc_battery.o

drivers/power/ltc2941-battery-gauge.c

0 → 100644
+547 −0
Original line number Diff line number Diff line 
/*

 * 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/idr.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 delayed_work work;	/* Work scheduler */

	int num_regs;	/* Number of registers (chip type) */

	int id;		/* Identifier of ltc294x chip */

	int charge;	/* Last charge register content */

	int r_sense;	/* mOhm */

	int Qlsb;	/* nAh */

};



static DEFINE_IDR(ltc294x_id);

static DEFINE_MUTEX(ltc294x_lock);



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 =

		container_of(psy, struct ltc294x_info, supply);



	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 =

		container_of(psy, struct ltc294x_info, supply);



	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);

	kfree(info->supply.name);

	mutex_lock(&ltc294x_lock);

	idr_remove(&ltc294x_id, info->id);

	mutex_unlock(&ltc294x_lock);

	return 0;

}



static int ltc294x_i2c_probe(struct i2c_client *client,

	const struct i2c_device_id *id)

{

	struct ltc294x_info *info;

	int ret;

	int num;

	u32 prescaler_exp;

	s32 r_sense;

	struct device_node *np;



	mutex_lock(&ltc294x_lock);

	ret = idr_alloc(&ltc294x_id, client, 0, 0, GFP_KERNEL);

	mutex_unlock(&ltc294x_lock);

	if (ret < 0)

		goto fail_id;



	num = ret;



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

	if (info == NULL) {

		ret = -ENOMEM;

		goto fail_info;

	}



	i2c_set_clientdata(client, info);



	info->num_regs = id->driver_data;

	info->supply.name = kasprintf(GFP_KERNEL, "%s-%d", client->name, num);

	if (!info->supply.name) {

		ret = -ENOMEM;

		goto fail_name;

	}



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



	/* 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");

		goto fail_name;

	}

	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 = ((58 * 50000) / r_sense) /

				(128 / (1 << prescaler_exp));

	}



	info->client = client;

	info->id = num;

	info->supply.type = POWER_SUPPLY_TYPE_BATTERY;

	info->supply.properties = ltc294x_properties;

	if (info->num_regs >= LTC294X_REG_TEMPERATURE_LSB)

		info->supply.num_properties =

			ARRAY_SIZE(ltc294x_properties);

	else if (info->num_regs >= LTC294X_REG_CURRENT_LSB)

		info->supply.num_properties =

			ARRAY_SIZE(ltc294x_properties) - 1;

	else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)

		info->supply.num_properties =

			ARRAY_SIZE(ltc294x_properties) - 2;

	else

		info->supply.num_properties =

			ARRAY_SIZE(ltc294x_properties) - 3;

	info->supply.get_property = ltc294x_get_property;

	info->supply.set_property = ltc294x_set_property;

	info->supply.property_is_writeable = ltc294x_property_is_writeable;

	info->supply.external_power_changed	= NULL;



	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");

		goto fail_comm;

	}



	ret = power_supply_register(&client->dev, &info->supply);

	if (ret) {

		dev_err(&client->dev, "failed to register ltc2941\n");

		goto fail_register;

	} else {

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

	}



	return 0;



fail_register:

	kfree(info->supply.name);

fail_comm:

fail_name:

fail_info:

	mutex_lock(&ltc294x_lock);

	idr_remove(&ltc294x_id, num);

	mutex_unlock(&ltc294x_lock);

fail_id:

	return ret;

}



#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");

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