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Add LTC2941/LTC2943 Battery Gauge Driver

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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: Mike Looijmans <mike.looijmans@topic.nl>
[ removed .owner field ]
Signed-off-by: Sebastian Reichel <sre@kernel.org>
This commit is contained in:
Mike Looijmans 2014-10-28 08:05:12 +01:00 committed by Sebastian Reichel
parent 79969f6aaf
commit 085bc24d15
3 changed files with 556 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
drivers/power/Kconfig
View File

@ -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

1
drivers/power/Makefile
View File

@ -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

547
drivers/power/ltc2941-battery-gauge.c Normal file
View File

@ -0,0 +1,547 @@
/*
* 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");