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/*
* I2C client/driver for the Maxim/Dallas DS2782 Stand-Alone Fuel Gauge IC
*
* Copyright (C) 2009 Bluewater Systems Ltd
*
* Author: Ryan Mallon <ryan@bluewatersys.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#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/idr.h>
#include <linux/power_supply.h>
#define DS2782_REG_RARC 0x06 /* Remaining active relative capacity */
#define DS2782_REG_VOLT_MSB 0x0c
#define DS2782_REG_TEMP_MSB 0x0a
#define DS2782_REG_CURRENT_MSB 0x0e
/* EEPROM Block */
#define DS2782_REG_RSNSP 0x69 /* Sense resistor value */
/* Current unit measurement in uA for a 1 milli-ohm sense resistor */
#define DS2782_CURRENT_UNITS 1563
#define to_ds2782_info(x) container_of(x, struct ds2782_info, battery)
struct ds2782_info {
struct i2c_client *client;
struct power_supply battery;
int id;
};
static DEFINE_IDR(battery_id);
static DEFINE_MUTEX(battery_lock);
static inline int ds2782_read_reg(struct ds2782_info *info, int reg, u8 *val)
{
int ret;
ret = i2c_smbus_read_byte_data(info->client, reg);
if (ret < 0) {
dev_err(&info->client->dev, "register read failed\n");
return ret;
}
*val = ret;
return 0;
}
static inline int ds2782_read_reg16(struct ds2782_info *info, int reg_msb,
s16 *val)
{
int ret;
ret = swab16(i2c_smbus_read_word_data(info->client, reg_msb));
if (ret < 0) {
dev_err(&info->client->dev, "register read failed\n");
return ret;
}
*val = ret;
return 0;
}
static int ds2782_get_temp(struct ds2782_info *info, int *temp)
{
s16 raw;
int err;
/*
* Temperature is measured in units of 0.125 degrees celcius, the
* power_supply class measures temperature in tenths of degrees
* celsius. The temperature value is stored as a 10 bit number, plus
* sign in the upper bits of a 16 bit register.
*/
err = ds2782_read_reg16(info, DS2782_REG_TEMP_MSB, &raw);
if (err)
return err;
*temp = ((raw / 32) * 125) / 100;
return 0;
}
static int ds2782_get_current(struct ds2782_info *info, int *current_uA)
{
int sense_res;
int err;
u8 sense_res_raw;
s16 raw;
/*
* The units of measurement for current are dependent on the value of
* the sense resistor.
*/
err = ds2782_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw);
if (err)
return err;
if (sense_res_raw == 0) {
dev_err(&info->client->dev, "sense resistor value is 0\n");
return -ENXIO;
}
sense_res = 1000 / sense_res_raw;
dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n",
sense_res);
err = ds2782_read_reg16(info, DS2782_REG_CURRENT_MSB, &raw);
if (err)
return err;
*current_uA = raw * (DS2782_CURRENT_UNITS / sense_res);
return 0;
}
static int ds2782_get_voltage(struct ds2782_info *info, int *voltage_uA)
{
s16 raw;
int err;
/*
* Voltage is measured in units of 4.88mV. The voltage is stored as
* a 10-bit number plus sign, in the upper bits of a 16-bit register
*/
err = ds2782_read_reg16(info, DS2782_REG_VOLT_MSB, &raw);
if (err)
return err;
*voltage_uA = (raw / 32) * 4800;
return 0;
}
static int ds2782_get_capacity(struct ds2782_info *info, int *capacity)
{
int err;
u8 raw;
err = ds2782_read_reg(info, DS2782_REG_RARC, &raw);
if (err)
return err;
*capacity = raw;
return raw;
}
static int ds2782_get_status(struct ds2782_info *info, int *status)
{
int err;
int current_uA;
int capacity;
err = ds2782_get_current(info, ¤t_uA);
if (err)
return err;
err = ds2782_get_capacity(info, &capacity);
if (err)
return err;
if (capacity == 100)
*status = POWER_SUPPLY_STATUS_FULL;
else if (current_uA == 0)
*status = POWER_SUPPLY_STATUS_NOT_CHARGING;
else if (current_uA < 0)
*status = POWER_SUPPLY_STATUS_DISCHARGING;
else
*status = POWER_SUPPLY_STATUS_CHARGING;
return 0;
}
static int ds2782_battery_get_property(struct power_supply *psy,
enum power_supply_property prop,
union power_supply_propval *val)
{
struct ds2782_info *info = to_ds2782_info(psy);
int ret;
switch (prop) {
case POWER_SUPPLY_PROP_STATUS:
ret = ds2782_get_status(info, &val->intval);
break;
case POWER_SUPPLY_PROP_CAPACITY:
ret = ds2782_get_capacity(info, &val->intval);
break;
case POWER_SUPPLY_PROP_VOLTAGE_NOW:
ret = ds2782_get_voltage(info, &val->intval);
break;
case POWER_SUPPLY_PROP_CURRENT_NOW:
ret = ds2782_get_current(info, &val->intval);
break;
case POWER_SUPPLY_PROP_TEMP:
ret = ds2782_get_temp(info, &val->intval);
break;
default:
ret = -EINVAL;
}
return ret;
}
static enum power_supply_property ds2782_battery_props[] = {
POWER_SUPPLY_PROP_STATUS,
POWER_SUPPLY_PROP_CAPACITY,
POWER_SUPPLY_PROP_VOLTAGE_NOW,
POWER_SUPPLY_PROP_CURRENT_NOW,
POWER_SUPPLY_PROP_TEMP,
};
static void ds2782_power_supply_init(struct power_supply *battery)
{
battery->type = POWER_SUPPLY_TYPE_BATTERY;
battery->properties = ds2782_battery_props;
battery->num_properties = ARRAY_SIZE(ds2782_battery_props);
battery->get_property = ds2782_battery_get_property;
battery->external_power_changed = NULL;
}
static int ds2782_battery_remove(struct i2c_client *client)
{
struct ds2782_info *info = i2c_get_clientdata(client);
power_supply_unregister(&info->battery);
kfree(info->battery.name);
mutex_lock(&battery_lock);
idr_remove(&battery_id, info->id);
mutex_unlock(&battery_lock);
kfree(info);
return 0;
}
static int ds2782_battery_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct ds2782_info *info;
int ret;
int num;
/* Get an ID for this battery */
ret = idr_pre_get(&battery_id, GFP_KERNEL);
if (ret == 0) {
ret = -ENOMEM;
goto fail_id;
}
mutex_lock(&battery_lock);
ret = idr_get_new(&battery_id, client, &num);
mutex_unlock(&battery_lock);
if (ret < 0)
goto fail_id;
info = kzalloc(sizeof(*info), GFP_KERNEL);
if (!info) {
ret = -ENOMEM;
goto fail_info;
}
info->battery.name = kasprintf(GFP_KERNEL, "ds2782-%d", num);
if (!info->battery.name) {
ret = -ENOMEM;
goto fail_name;
}
i2c_set_clientdata(client, info);
info->client = client;
ds2782_power_supply_init(&info->battery);
ret = power_supply_register(&client->dev, &info->battery);
if (ret) {
dev_err(&client->dev, "failed to register battery\n");
goto fail_register;
}
return 0;
fail_register:
kfree(info->battery.name);
fail_name:
kfree(info);
fail_info:
mutex_lock(&battery_lock);
idr_remove(&battery_id, num);
mutex_unlock(&battery_lock);
fail_id:
return ret;
}
static const struct i2c_device_id ds2782_id[] = {
{"ds2782", 0},
{},
};
static struct i2c_driver ds2782_battery_driver = {
.driver = {
.name = "ds2782-battery",
},
.probe = ds2782_battery_probe,
.remove = ds2782_battery_remove,
.id_table = ds2782_id,
};
static int __init ds2782_init(void)
{
return i2c_add_driver(&ds2782_battery_driver);
}
module_init(ds2782_init);
static void __exit ds2782_exit(void)
{
i2c_del_driver(&ds2782_battery_driver);
}
module_exit(ds2782_exit);
MODULE_AUTHOR("Ryan Mallon <ryan@bluewatersys.com>");
MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauage IC driver");
MODULE_LICENSE("GPL");
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