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linux/drivers/power/bq27x00_battery.c
Lars-Peter Clausen 0e9f30497e bq27x00: Improve temperature property precession 
This patch improves the precession of the temperature property of the
bq27x00 driver.
By dividing before multiplying the current code effectively cuts of the
last decimal digit. This patch fixes it by multiplying before dividing.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Rodolfo Giometti <giometti@linux.it>
Tested-by: Grazvydas Ignotas <notasas@gmail.com>
2011-02-22 11:02:39 +01:00

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/*
* BQ27x00 battery driver
*
* Copyright (C) 2008 Rodolfo Giometti <giometti@linux.it>
* Copyright (C) 2008 Eurotech S.p.A. <info@eurotech.it>
*
* Based on a previous work by Copyright (C) 2008 Texas Instruments, Inc.
*
* This package 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.
*
* THIS PACKAGE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
*/
#include <linux/module.h>
#include <linux/param.h>
#include <linux/jiffies.h>
#include <linux/workqueue.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/power_supply.h>
#include <linux/idr.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <asm/unaligned.h>
#define DRIVER_VERSION "1.1.0"
#define BQ27x00_REG_TEMP 0x06
#define BQ27x00_REG_VOLT 0x08
#define BQ27x00_REG_AI 0x14
#define BQ27x00_REG_FLAGS 0x0A
#define BQ27x00_REG_TTE 0x16
#define BQ27x00_REG_TTF 0x18
#define BQ27x00_REG_TTECP 0x26
#define BQ27000_REG_RSOC 0x0B /* Relative State-of-Charge */
#define BQ27000_FLAG_CHGS BIT(7)
#define BQ27500_REG_SOC 0x2c
#define BQ27500_FLAG_DSC BIT(0)
#define BQ27500_FLAG_FC BIT(9)
/* If the system has several batteries we need a different name for each
* of them...
*/
static DEFINE_IDR(battery_id);
static DEFINE_MUTEX(battery_mutex);
struct bq27x00_device_info;
struct bq27x00_access_methods {
int (*read)(u8 reg, int *rt_value, int b_single,
struct bq27x00_device_info *di);
};
enum bq27x00_chip { BQ27000, BQ27500 };
struct bq27x00_device_info {
struct device *dev;
int id;
struct bq27x00_access_methods *bus;
struct power_supply bat;
enum bq27x00_chip chip;
struct i2c_client *client;
};
static enum power_supply_property bq27x00_battery_props[] = {
POWER_SUPPLY_PROP_STATUS,
POWER_SUPPLY_PROP_PRESENT,
POWER_SUPPLY_PROP_VOLTAGE_NOW,
POWER_SUPPLY_PROP_CURRENT_NOW,
POWER_SUPPLY_PROP_CAPACITY,
POWER_SUPPLY_PROP_TEMP,
POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW,
POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG,
POWER_SUPPLY_PROP_TIME_TO_FULL_NOW,
POWER_SUPPLY_PROP_TECHNOLOGY,
};
/*
* Common code for BQ27x00 devices
*/
static int bq27x00_read(u8 reg, int *rt_value, int b_single,
struct bq27x00_device_info *di)
{
return di->bus->read(reg, rt_value, b_single, di);
}
/*
* Return the battery temperature in tenths of degree Celsius
* Or < 0 if something fails.
*/
static int bq27x00_battery_temperature(struct bq27x00_device_info *di)
{
int ret;
int temp = 0;
ret = bq27x00_read(BQ27x00_REG_TEMP, &temp, 0, di);
if (ret) {
dev_err(di->dev, "error reading temperature\n");
return ret;
}
if (di->chip == BQ27500)
return temp - 2731;
else
return ((temp * 5) - 5463) / 2;
}
/*
* Return the battery Voltage in milivolts
* Or < 0 if something fails.
*/
static int bq27x00_battery_voltage(struct bq27x00_device_info *di)
{
int ret;
int volt = 0;
ret = bq27x00_read(BQ27x00_REG_VOLT, &volt, 0, di);
if (ret) {
dev_err(di->dev, "error reading voltage\n");
return ret;
}
return volt * 1000;
}
/*
* Return the battery average current
* Note that current can be negative signed as well
* Or 0 if something fails.
*/
static int bq27x00_battery_current(struct bq27x00_device_info *di)
{
int ret;
int curr = 0;
int flags = 0;
ret = bq27x00_read(BQ27x00_REG_AI, &curr, 0, di);
if (ret) {
dev_err(di->dev, "error reading current\n");
return 0;
}
if (di->chip == BQ27500) {
/* bq27500 returns signed value */
curr = (int)(s16)curr;
} else {
ret = bq27x00_read(BQ27x00_REG_FLAGS, &flags, 0, di);
if (ret < 0) {
dev_err(di->dev, "error reading flags\n");
return 0;
}
if (flags & BQ27000_FLAG_CHGS) {
dev_dbg(di->dev, "negative current!\n");
curr = -curr;
}
}
return curr * 1000;
}
/*
* Return the battery Relative State-of-Charge
* Or < 0 if something fails.
*/
static int bq27x00_battery_rsoc(struct bq27x00_device_info *di)
{
int ret;
int rsoc = 0;
if (di->chip == BQ27500)
ret = bq27x00_read(BQ27500_REG_SOC, &rsoc, 0, di);
else
ret = bq27x00_read(BQ27000_REG_RSOC, &rsoc, 1, di);
if (ret) {
dev_err(di->dev, "error reading relative State-of-Charge\n");
return ret;
}
return rsoc;
}
static int bq27x00_battery_status(struct bq27x00_device_info *di,
union power_supply_propval *val)
{
int flags = 0;
int status;
int ret;
ret = bq27x00_read(BQ27x00_REG_FLAGS, &flags, 0, di);
if (ret < 0) {
dev_err(di->dev, "error reading flags\n");
return ret;
}
if (di->chip == BQ27500) {
if (flags & BQ27500_FLAG_FC)
status = POWER_SUPPLY_STATUS_FULL;
else if (flags & BQ27500_FLAG_DSC)
status = POWER_SUPPLY_STATUS_DISCHARGING;
else
status = POWER_SUPPLY_STATUS_CHARGING;
} else {
if (flags & BQ27000_FLAG_CHGS)
status = POWER_SUPPLY_STATUS_CHARGING;
else
status = POWER_SUPPLY_STATUS_DISCHARGING;
}
val->intval = status;
return 0;
}
/*
* Read a time register.
* Return < 0 if something fails.
*/
static int bq27x00_battery_time(struct bq27x00_device_info *di, int reg,
union power_supply_propval *val)
{
int tval = 0;
int ret;
ret = bq27x00_read(reg, &tval, 0, di);
if (ret) {
dev_err(di->dev, "error reading register %02x\n", reg);
return ret;
}
if (tval == 65535)
return -ENODATA;
val->intval = tval * 60;
return 0;
}
#define to_bq27x00_device_info(x) container_of((x), \
struct bq27x00_device_info, bat);
static int bq27x00_battery_get_property(struct power_supply *psy,
enum power_supply_property psp,
union power_supply_propval *val)
{
int ret = 0;
struct bq27x00_device_info *di = to_bq27x00_device_info(psy);
switch (psp) {
case POWER_SUPPLY_PROP_STATUS:
ret = bq27x00_battery_status(di, val);
break;
case POWER_SUPPLY_PROP_VOLTAGE_NOW:
case POWER_SUPPLY_PROP_PRESENT:
val->intval = bq27x00_battery_voltage(di);
if (psp == POWER_SUPPLY_PROP_PRESENT)
val->intval = val->intval <= 0 ? 0 : 1;
break;
case POWER_SUPPLY_PROP_CURRENT_NOW:
val->intval = bq27x00_battery_current(di);
break;
case POWER_SUPPLY_PROP_CAPACITY:
val->intval = bq27x00_battery_rsoc(di);
break;
case POWER_SUPPLY_PROP_TEMP:
val->intval = bq27x00_battery_temperature(di);
break;
case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
ret = bq27x00_battery_time(di, BQ27x00_REG_TTE, val);
break;
case POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG:
ret = bq27x00_battery_time(di, BQ27x00_REG_TTECP, val);
break;
case POWER_SUPPLY_PROP_TIME_TO_FULL_NOW:
ret = bq27x00_battery_time(di, BQ27x00_REG_TTF, val);
break;
case POWER_SUPPLY_PROP_TECHNOLOGY:
val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
break;
default:
return -EINVAL;
}
return ret;
}
static void bq27x00_powersupply_init(struct bq27x00_device_info *di)
{
di->bat.type = POWER_SUPPLY_TYPE_BATTERY;
di->bat.properties = bq27x00_battery_props;
di->bat.num_properties = ARRAY_SIZE(bq27x00_battery_props);
di->bat.get_property = bq27x00_battery_get_property;
di->bat.external_power_changed = NULL;
}
/*
* i2c specific code
*/
static int bq27x00_read_i2c(u8 reg, int *rt_value, int b_single,
struct bq27x00_device_info *di)
{
struct i2c_client *client = di->client;
struct i2c_msg msg[1];
unsigned char data[2];
int err;
if (!client->adapter)
return -ENODEV;
msg->addr = client->addr;
msg->flags = 0;
msg->len = 1;
msg->buf = data;
data[0] = reg;
err = i2c_transfer(client->adapter, msg, 1);
if (err >= 0) {
if (!b_single)
msg->len = 2;
else
msg->len = 1;
msg->flags = I2C_M_RD;
err = i2c_transfer(client->adapter, msg, 1);
if (err >= 0) {
if (!b_single)
*rt_value = get_unaligned_le16(data);
else
*rt_value = data[0];
return 0;
}
}
return err;
}
static int bq27x00_battery_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
char *name;
struct bq27x00_device_info *di;
struct bq27x00_access_methods *bus;
int num;
int retval = 0;
/* Get new ID for the new battery device */
retval = idr_pre_get(&battery_id, GFP_KERNEL);
if (retval == 0)
return -ENOMEM;
mutex_lock(&battery_mutex);
retval = idr_get_new(&battery_id, client, &num);
mutex_unlock(&battery_mutex);
if (retval < 0)
return retval;
name = kasprintf(GFP_KERNEL, "%s-%d", id->name, num);
if (!name) {
dev_err(&client->dev, "failed to allocate device name\n");
retval = -ENOMEM;
goto batt_failed_1;
}
di = kzalloc(sizeof(*di), GFP_KERNEL);
if (!di) {
dev_err(&client->dev, "failed to allocate device info data\n");
retval = -ENOMEM;
goto batt_failed_2;
}
di->id = num;
di->chip = id->driver_data;
bus = kzalloc(sizeof(*bus), GFP_KERNEL);
if (!bus) {
dev_err(&client->dev, "failed to allocate access method "
"data\n");
retval = -ENOMEM;
goto batt_failed_3;
}
i2c_set_clientdata(client, di);
di->dev = &client->dev;
di->bat.name = name;
bus->read = &bq27x00_read_i2c;
di->bus = bus;
di->client = client;
bq27x00_powersupply_init(di);
retval = power_supply_register(&client->dev, &di->bat);
if (retval) {
dev_err(&client->dev, "failed to register battery\n");
goto batt_failed_4;
}
dev_info(&client->dev, "support ver. %s enabled\n", DRIVER_VERSION);
return 0;
batt_failed_4:
kfree(bus);
batt_failed_3:
kfree(di);
batt_failed_2:
kfree(name);
batt_failed_1:
mutex_lock(&battery_mutex);
idr_remove(&battery_id, num);
mutex_unlock(&battery_mutex);
return retval;
}
static int bq27x00_battery_remove(struct i2c_client *client)
{
struct bq27x00_device_info *di = i2c_get_clientdata(client);
power_supply_unregister(&di->bat);
kfree(di->bus);
kfree(di->bat.name);
mutex_lock(&battery_mutex);
idr_remove(&battery_id, di->id);
mutex_unlock(&battery_mutex);
kfree(di);
return 0;
}
/*
* Module stuff
*/
static const struct i2c_device_id bq27x00_id[] = {
{ "bq27200", BQ27000 }, /* bq27200 is same as bq27000, but with i2c */
{ "bq27500", BQ27500 },
{},
};
static struct i2c_driver bq27x00_battery_driver = {
.driver = {
.name = "bq27x00-battery",
},
.probe = bq27x00_battery_probe,
.remove = bq27x00_battery_remove,
.id_table = bq27x00_id,
};
static int __init bq27x00_battery_init(void)
{
int ret;
ret = i2c_add_driver(&bq27x00_battery_driver);
if (ret)
printk(KERN_ERR "Unable to register BQ27x00 driver\n");
return ret;
}
module_init(bq27x00_battery_init);
static void __exit bq27x00_battery_exit(void)
{
i2c_del_driver(&bq27x00_battery_driver);
}
module_exit(bq27x00_battery_exit);
MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
MODULE_DESCRIPTION("BQ27x00 battery monitor driver");
MODULE_LICENSE("GPL");
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