ds2782_battery.c revision a009d29ea104c1bd8805a20018469897c2c2263c
1/* 2 * I2C client/driver for the Maxim/Dallas DS2782 Stand-Alone Fuel Gauge IC 3 * 4 * Copyright (C) 2009 Bluewater Systems Ltd 5 * 6 * Author: Ryan Mallon <ryan@bluewatersys.com> 7 * 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. 11 * 12 */ 13 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 23#define DS2782_REG_RARC 0x06 /* Remaining active relative capacity */ 24 25#define DS2782_REG_VOLT_MSB 0x0c 26#define DS2782_REG_TEMP_MSB 0x0a 27#define DS2782_REG_CURRENT_MSB 0x0e 28 29/* EEPROM Block */ 30#define DS2782_REG_RSNSP 0x69 /* Sense resistor value */ 31 32/* Current unit measurement in uA for a 1 milli-ohm sense resistor */ 33#define DS2782_CURRENT_UNITS 1563 34 35#define to_ds2782_info(x) container_of(x, struct ds2782_info, battery) 36 37struct ds2782_info { 38 struct i2c_client *client; 39 struct power_supply battery; 40 int id; 41}; 42 43static DEFINE_IDR(battery_id); 44static DEFINE_MUTEX(battery_lock); 45 46static inline int ds2782_read_reg(struct ds2782_info *info, int reg, u8 *val) 47{ 48 int ret; 49 50 ret = i2c_smbus_read_byte_data(info->client, reg); 51 if (ret < 0) { 52 dev_err(&info->client->dev, "register read failed\n"); 53 return ret; 54 } 55 56 *val = ret; 57 return 0; 58} 59 60static inline int ds2782_read_reg16(struct ds2782_info *info, int reg_msb, 61 s16 *val) 62{ 63 int ret; 64 65 ret = swab16(i2c_smbus_read_word_data(info->client, reg_msb)); 66 if (ret < 0) { 67 dev_err(&info->client->dev, "register read failed\n"); 68 return ret; 69 } 70 71 *val = ret; 72 return 0; 73} 74 75static int ds2782_get_temp(struct ds2782_info *info, int *temp) 76{ 77 s16 raw; 78 int err; 79 80 /* 81 * Temperature is measured in units of 0.125 degrees celcius, the 82 * power_supply class measures temperature in tenths of degrees 83 * celsius. The temperature value is stored as a 10 bit number, plus 84 * sign in the upper bits of a 16 bit register. 85 */ 86 err = ds2782_read_reg16(info, DS2782_REG_TEMP_MSB, &raw); 87 if (err) 88 return err; 89 *temp = ((raw / 32) * 125) / 100; 90 return 0; 91} 92 93static int ds2782_get_current(struct ds2782_info *info, int *current_uA) 94{ 95 int sense_res; 96 int err; 97 u8 sense_res_raw; 98 s16 raw; 99 100 /* 101 * The units of measurement for current are dependent on the value of 102 * the sense resistor. 103 */ 104 err = ds2782_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw); 105 if (err) 106 return err; 107 if (sense_res_raw == 0) { 108 dev_err(&info->client->dev, "sense resistor value is 0\n"); 109 return -ENXIO; 110 } 111 sense_res = 1000 / sense_res_raw; 112 113 dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n", 114 sense_res); 115 err = ds2782_read_reg16(info, DS2782_REG_CURRENT_MSB, &raw); 116 if (err) 117 return err; 118 *current_uA = raw * (DS2782_CURRENT_UNITS / sense_res); 119 return 0; 120} 121 122static int ds2782_get_voltage(struct ds2782_info *info, int *voltage_uA) 123{ 124 s16 raw; 125 int err; 126 127 /* 128 * Voltage is measured in units of 4.88mV. The voltage is stored as 129 * a 10-bit number plus sign, in the upper bits of a 16-bit register 130 */ 131 err = ds2782_read_reg16(info, DS2782_REG_VOLT_MSB, &raw); 132 if (err) 133 return err; 134 *voltage_uA = (raw / 32) * 4800; 135 return 0; 136} 137 138static int ds2782_get_capacity(struct ds2782_info *info, int *capacity) 139{ 140 int err; 141 u8 raw; 142 143 err = ds2782_read_reg(info, DS2782_REG_RARC, &raw); 144 if (err) 145 return err; 146 *capacity = raw; 147 return raw; 148} 149 150static int ds2782_get_status(struct ds2782_info *info, int *status) 151{ 152 int err; 153 int current_uA; 154 int capacity; 155 156 err = ds2782_get_current(info, ¤t_uA); 157 if (err) 158 return err; 159 160 err = ds2782_get_capacity(info, &capacity); 161 if (err) 162 return err; 163 164 if (capacity == 100) 165 *status = POWER_SUPPLY_STATUS_FULL; 166 else if (current_uA == 0) 167 *status = POWER_SUPPLY_STATUS_NOT_CHARGING; 168 else if (current_uA < 0) 169 *status = POWER_SUPPLY_STATUS_DISCHARGING; 170 else 171 *status = POWER_SUPPLY_STATUS_CHARGING; 172 173 return 0; 174} 175 176static int ds2782_battery_get_property(struct power_supply *psy, 177 enum power_supply_property prop, 178 union power_supply_propval *val) 179{ 180 struct ds2782_info *info = to_ds2782_info(psy); 181 int ret; 182 183 switch (prop) { 184 case POWER_SUPPLY_PROP_STATUS: 185 ret = ds2782_get_status(info, &val->intval); 186 break; 187 188 case POWER_SUPPLY_PROP_CAPACITY: 189 ret = ds2782_get_capacity(info, &val->intval); 190 break; 191 192 case POWER_SUPPLY_PROP_VOLTAGE_NOW: 193 ret = ds2782_get_voltage(info, &val->intval); 194 break; 195 196 case POWER_SUPPLY_PROP_CURRENT_NOW: 197 ret = ds2782_get_current(info, &val->intval); 198 break; 199 200 case POWER_SUPPLY_PROP_TEMP: 201 ret = ds2782_get_temp(info, &val->intval); 202 break; 203 204 default: 205 ret = -EINVAL; 206 } 207 208 return ret; 209} 210 211static enum power_supply_property ds2782_battery_props[] = { 212 POWER_SUPPLY_PROP_STATUS, 213 POWER_SUPPLY_PROP_CAPACITY, 214 POWER_SUPPLY_PROP_VOLTAGE_NOW, 215 POWER_SUPPLY_PROP_CURRENT_NOW, 216 POWER_SUPPLY_PROP_TEMP, 217}; 218 219static void ds2782_power_supply_init(struct power_supply *battery) 220{ 221 battery->type = POWER_SUPPLY_TYPE_BATTERY; 222 battery->properties = ds2782_battery_props; 223 battery->num_properties = ARRAY_SIZE(ds2782_battery_props); 224 battery->get_property = ds2782_battery_get_property; 225 battery->external_power_changed = NULL; 226} 227 228static int ds2782_battery_remove(struct i2c_client *client) 229{ 230 struct ds2782_info *info = i2c_get_clientdata(client); 231 232 power_supply_unregister(&info->battery); 233 kfree(info->battery.name); 234 235 mutex_lock(&battery_lock); 236 idr_remove(&battery_id, info->id); 237 mutex_unlock(&battery_lock); 238 239 kfree(info); 240 return 0; 241} 242 243static int ds2782_battery_probe(struct i2c_client *client, 244 const struct i2c_device_id *id) 245{ 246 struct ds2782_info *info; 247 int ret; 248 int num; 249 250 /* Get an ID for this battery */ 251 ret = idr_pre_get(&battery_id, GFP_KERNEL); 252 if (ret == 0) { 253 ret = -ENOMEM; 254 goto fail_id; 255 } 256 257 mutex_lock(&battery_lock); 258 ret = idr_get_new(&battery_id, client, &num); 259 mutex_unlock(&battery_lock); 260 if (ret < 0) 261 goto fail_id; 262 263 info = kzalloc(sizeof(*info), GFP_KERNEL); 264 if (!info) { 265 ret = -ENOMEM; 266 goto fail_info; 267 } 268 269 info->battery.name = kasprintf(GFP_KERNEL, "ds2782-%d", num); 270 if (!info->battery.name) { 271 ret = -ENOMEM; 272 goto fail_name; 273 } 274 275 i2c_set_clientdata(client, info); 276 info->client = client; 277 ds2782_power_supply_init(&info->battery); 278 279 ret = power_supply_register(&client->dev, &info->battery); 280 if (ret) { 281 dev_err(&client->dev, "failed to register battery\n"); 282 goto fail_register; 283 } 284 285 return 0; 286 287fail_register: 288 kfree(info->battery.name); 289fail_name: 290 kfree(info); 291fail_info: 292 mutex_lock(&battery_lock); 293 idr_remove(&battery_id, num); 294 mutex_unlock(&battery_lock); 295fail_id: 296 return ret; 297} 298 299static const struct i2c_device_id ds2782_id[] = { 300 {"ds2782", 0}, 301 {}, 302}; 303 304static struct i2c_driver ds2782_battery_driver = { 305 .driver = { 306 .name = "ds2782-battery", 307 }, 308 .probe = ds2782_battery_probe, 309 .remove = ds2782_battery_remove, 310 .id_table = ds2782_id, 311}; 312 313static int __init ds2782_init(void) 314{ 315 return i2c_add_driver(&ds2782_battery_driver); 316} 317module_init(ds2782_init); 318 319static void __exit ds2782_exit(void) 320{ 321 i2c_del_driver(&ds2782_battery_driver); 322} 323module_exit(ds2782_exit); 324 325MODULE_AUTHOR("Ryan Mallon <ryan@bluewatersys.com>"); 326MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauage IC driver"); 327MODULE_LICENSE("GPL"); 328