2 * I2C client/driver for the Maxim/Dallas DS2782 Stand-Alone Fuel Gauge IC
4 * Copyright (C) 2009 Bluewater Systems Ltd
6 * Author: Ryan Mallon <ryan@bluewatersys.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/types.h>
17 #include <linux/errno.h>
18 #include <linux/swab.h>
19 #include <linux/i2c.h>
20 #include <linux/idr.h>
21 #include <linux/power_supply.h>
22 #include <linux/slab.h>
24 #define DS2782_REG_RARC 0x06 /* Remaining active relative capacity */
26 #define DS2782_REG_VOLT_MSB 0x0c
27 #define DS2782_REG_TEMP_MSB 0x0a
28 #define DS2782_REG_CURRENT_MSB 0x0e
31 #define DS2782_REG_RSNSP 0x69 /* Sense resistor value */
33 /* Current unit measurement in uA for a 1 milli-ohm sense resistor */
34 #define DS2782_CURRENT_UNITS 1563
36 #define to_ds2782_info(x) container_of(x, struct ds2782_info, battery)
39 struct i2c_client *client;
40 struct power_supply battery;
44 static DEFINE_IDR(battery_id);
45 static DEFINE_MUTEX(battery_lock);
47 static inline int ds2782_read_reg(struct ds2782_info *info, int reg, u8 *val)
51 ret = i2c_smbus_read_byte_data(info->client, reg);
53 dev_err(&info->client->dev, "register read failed\n");
61 static inline int ds2782_read_reg16(struct ds2782_info *info, int reg_msb,
66 ret = swab16(i2c_smbus_read_word_data(info->client, reg_msb));
68 dev_err(&info->client->dev, "register read failed\n");
76 static int ds2782_get_temp(struct ds2782_info *info, int *temp)
82 * Temperature is measured in units of 0.125 degrees celcius, the
83 * power_supply class measures temperature in tenths of degrees
84 * celsius. The temperature value is stored as a 10 bit number, plus
85 * sign in the upper bits of a 16 bit register.
87 err = ds2782_read_reg16(info, DS2782_REG_TEMP_MSB, &raw);
90 *temp = ((raw / 32) * 125) / 100;
94 static int ds2782_get_current(struct ds2782_info *info, int *current_uA)
102 * The units of measurement for current are dependent on the value of
103 * the sense resistor.
105 err = ds2782_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw);
108 if (sense_res_raw == 0) {
109 dev_err(&info->client->dev, "sense resistor value is 0\n");
112 sense_res = 1000 / sense_res_raw;
114 dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n",
116 err = ds2782_read_reg16(info, DS2782_REG_CURRENT_MSB, &raw);
119 *current_uA = raw * (DS2782_CURRENT_UNITS / sense_res);
123 static int ds2782_get_voltage(struct ds2782_info *info, int *voltage_uA)
129 * Voltage is measured in units of 4.88mV. The voltage is stored as
130 * a 10-bit number plus sign, in the upper bits of a 16-bit register
132 err = ds2782_read_reg16(info, DS2782_REG_VOLT_MSB, &raw);
135 *voltage_uA = (raw / 32) * 4800;
139 static int ds2782_get_capacity(struct ds2782_info *info, int *capacity)
144 err = ds2782_read_reg(info, DS2782_REG_RARC, &raw);
151 static int ds2782_get_status(struct ds2782_info *info, int *status)
157 err = ds2782_get_current(info, ¤t_uA);
161 err = ds2782_get_capacity(info, &capacity);
166 *status = POWER_SUPPLY_STATUS_FULL;
167 else if (current_uA == 0)
168 *status = POWER_SUPPLY_STATUS_NOT_CHARGING;
169 else if (current_uA < 0)
170 *status = POWER_SUPPLY_STATUS_DISCHARGING;
172 *status = POWER_SUPPLY_STATUS_CHARGING;
177 static int ds2782_battery_get_property(struct power_supply *psy,
178 enum power_supply_property prop,
179 union power_supply_propval *val)
181 struct ds2782_info *info = to_ds2782_info(psy);
185 case POWER_SUPPLY_PROP_STATUS:
186 ret = ds2782_get_status(info, &val->intval);
189 case POWER_SUPPLY_PROP_CAPACITY:
190 ret = ds2782_get_capacity(info, &val->intval);
193 case POWER_SUPPLY_PROP_VOLTAGE_NOW:
194 ret = ds2782_get_voltage(info, &val->intval);
197 case POWER_SUPPLY_PROP_CURRENT_NOW:
198 ret = ds2782_get_current(info, &val->intval);
201 case POWER_SUPPLY_PROP_TEMP:
202 ret = ds2782_get_temp(info, &val->intval);
212 static enum power_supply_property ds2782_battery_props[] = {
213 POWER_SUPPLY_PROP_STATUS,
214 POWER_SUPPLY_PROP_CAPACITY,
215 POWER_SUPPLY_PROP_VOLTAGE_NOW,
216 POWER_SUPPLY_PROP_CURRENT_NOW,
217 POWER_SUPPLY_PROP_TEMP,
220 static void ds2782_power_supply_init(struct power_supply *battery)
222 battery->type = POWER_SUPPLY_TYPE_BATTERY;
223 battery->properties = ds2782_battery_props;
224 battery->num_properties = ARRAY_SIZE(ds2782_battery_props);
225 battery->get_property = ds2782_battery_get_property;
226 battery->external_power_changed = NULL;
229 static int ds2782_battery_remove(struct i2c_client *client)
231 struct ds2782_info *info = i2c_get_clientdata(client);
233 power_supply_unregister(&info->battery);
234 kfree(info->battery.name);
236 mutex_lock(&battery_lock);
237 idr_remove(&battery_id, info->id);
238 mutex_unlock(&battery_lock);
240 i2c_set_clientdata(client, info);
246 static int ds2782_battery_probe(struct i2c_client *client,
247 const struct i2c_device_id *id)
249 struct ds2782_info *info;
253 /* Get an ID for this battery */
254 ret = idr_pre_get(&battery_id, GFP_KERNEL);
260 mutex_lock(&battery_lock);
261 ret = idr_get_new(&battery_id, client, &num);
262 mutex_unlock(&battery_lock);
266 info = kzalloc(sizeof(*info), GFP_KERNEL);
272 info->battery.name = kasprintf(GFP_KERNEL, "ds2782-%d", num);
273 if (!info->battery.name) {
278 i2c_set_clientdata(client, info);
279 info->client = client;
280 ds2782_power_supply_init(&info->battery);
282 ret = power_supply_register(&client->dev, &info->battery);
284 dev_err(&client->dev, "failed to register battery\n");
291 kfree(info->battery.name);
293 i2c_set_clientdata(client, info);
296 mutex_lock(&battery_lock);
297 idr_remove(&battery_id, num);
298 mutex_unlock(&battery_lock);
303 static const struct i2c_device_id ds2782_id[] = {
308 static struct i2c_driver ds2782_battery_driver = {
310 .name = "ds2782-battery",
312 .probe = ds2782_battery_probe,
313 .remove = ds2782_battery_remove,
314 .id_table = ds2782_id,
317 static int __init ds2782_init(void)
319 return i2c_add_driver(&ds2782_battery_driver);
321 module_init(ds2782_init);
323 static void __exit ds2782_exit(void)
325 i2c_del_driver(&ds2782_battery_driver);
327 module_exit(ds2782_exit);
329 MODULE_AUTHOR("Ryan Mallon <ryan@bluewatersys.com>");
330 MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauage IC driver");
331 MODULE_LICENSE("GPL");