drivers/power/ds2782_battery.c

   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  * DS2786 added by Yulia Vilensky <vilensky@compulab.co.il>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  *
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/types.h>
  19 #include <linux/errno.h>
  20 #include <linux/swab.h>
  21 #include <linux/i2c.h>
  22 #include <linux/idr.h>
  23 #include <linux/power_supply.h>
  24 #include <linux/slab.h>
  25 #include <linux/ds2782_battery.h>
  26
  27 #define DS2782_REG_RARC         0x06    /* Remaining active relative capacity */
  28
  29 #define DS278x_REG_VOLT_MSB     0x0c
  30 #define DS278x_REG_TEMP_MSB     0x0a
  31 #define DS278x_REG_CURRENT_MSB  0x0e
  32
  33 /* EEPROM Block */
  34 #define DS2782_REG_RSNSP        0x69    /* Sense resistor value */
  35
  36 /* Current unit measurement in uA for a 1 milli-ohm sense resistor */
  37 #define DS2782_CURRENT_UNITS    1563
  38
  39 #define DS2786_REG_RARC         0x02    /* Remaining active relative capacity */
  40
  41 #define DS2786_CURRENT_UNITS    25
  42
  43 struct ds278x_info;
  44
  45 struct ds278x_battery_ops {
  46         int (*get_battery_current)(struct ds278x_info *info, int *current_uA);
  47         int (*get_battery_voltage)(struct ds278x_info *info, int *voltage_uV);
  48         int (*get_battery_capacity)(struct ds278x_info *info, int *capacity);
  49 };
  50
  51 #define to_ds278x_info(x) container_of(x, struct ds278x_info, battery)
  52
  53 struct ds278x_info {
  54         struct i2c_client       *client;
  55         struct power_supply     battery;
  56         struct ds278x_battery_ops  *ops;
  57         int                     id;
  58         int                     rsns;
  59 };
  60
  61 static DEFINE_IDR(battery_id);
  62 static DEFINE_MUTEX(battery_lock);
  63
  64 static inline int ds278x_read_reg(struct ds278x_info *info, int reg, u8 *val)
  65 {
  66         int ret;
  67
  68         ret = i2c_smbus_read_byte_data(info->client, reg);
  69         if (ret < 0) {
  70                 dev_err(&info->client->dev, "register read failed\n");
  71                 return ret;
  72         }
  73
  74         *val = ret;
  75         return 0;
  76 }
  77
  78 static inline int ds278x_read_reg16(struct ds278x_info *info, int reg_msb,
  79                                     s16 *val)
  80 {
  81         int ret;
  82
  83         ret = swab16(i2c_smbus_read_word_data(info->client, reg_msb));
  84         if (ret < 0) {
  85                 dev_err(&info->client->dev, "register read failed\n");
  86                 return ret;
  87         }
  88
  89         *val = ret;
  90         return 0;
  91 }
  92
  93 static int ds278x_get_temp(struct ds278x_info *info, int *temp)
  94 {
  95         s16 raw;
  96         int err;
  97
  98         /*
  99          * Temperature is measured in units of 0.125 degrees celcius, the
 100          * power_supply class measures temperature in tenths of degrees
 101          * celsius. The temperature value is stored as a 10 bit number, plus
 102          * sign in the upper bits of a 16 bit register.
 103          */
 104         err = ds278x_read_reg16(info, DS278x_REG_TEMP_MSB, &raw);
 105         if (err)
 106                 return err;
 107         *temp = ((raw / 32) * 125) / 100;
 108         return 0;
 109 }
 110
 111 static int ds2782_get_current(struct ds278x_info *info, int *current_uA)
 112 {
 113         int sense_res;
 114         int err;
 115         u8 sense_res_raw;
 116         s16 raw;
 117
 118         /*
 119          * The units of measurement for current are dependent on the value of
 120          * the sense resistor.
 121          */
 122         err = ds278x_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw);
 123         if (err)
 124                 return err;
 125         if (sense_res_raw == 0) {
 126                 dev_err(&info->client->dev, "sense resistor value is 0\n");
 127                 return -ENXIO;
 128         }
 129         sense_res = 1000 / sense_res_raw;
 130
 131         dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n",
 132                 sense_res);
 133         err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
 134         if (err)
 135                 return err;
 136         *current_uA = raw * (DS2782_CURRENT_UNITS / sense_res);
 137         return 0;
 138 }
 139
 140 static int ds2782_get_voltage(struct ds278x_info *info, int *voltage_uV)
 141 {
 142         s16 raw;
 143         int err;
 144
 145         /*
 146          * Voltage is measured in units of 4.88mV. The voltage is stored as
 147          * a 10-bit number plus sign, in the upper bits of a 16-bit register
 148          */
 149         err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
 150         if (err)
 151                 return err;
 152         *voltage_uV = (raw / 32) * 4800;
 153         return 0;
 154 }
 155
 156 static int ds2782_get_capacity(struct ds278x_info *info, int *capacity)
 157 {
 158         int err;
 159         u8 raw;
 160
 161         err = ds278x_read_reg(info, DS2782_REG_RARC, &raw);
 162         if (err)
 163                 return err;
 164         *capacity = raw;
 165         return 0;
 166 }
 167
 168 static int ds2786_get_current(struct ds278x_info *info, int *current_uA)
 169 {
 170         int err;
 171         s16 raw;
 172
 173         err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
 174         if (err)
 175                 return err;
 176         *current_uA = (raw / 16) * (DS2786_CURRENT_UNITS / info->rsns);
 177         return 0;
 178 }
 179
 180 static int ds2786_get_voltage(struct ds278x_info *info, int *voltage_uV)
 181 {
 182         s16 raw;
 183         int err;
 184
 185         /*
 186          * Voltage is measured in units of 1.22mV. The voltage is stored as
 187          * a 10-bit number plus sign, in the upper bits of a 16-bit register
 188          */
 189         err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
 190         if (err)
 191                 return err;
 192         *voltage_uV = (raw / 8) * 1220;
 193         return 0;
 194 }
 195
 196 static int ds2786_get_capacity(struct ds278x_info *info, int *capacity)
 197 {
 198         int err;
 199         u8 raw;
 200
 201         err = ds278x_read_reg(info, DS2786_REG_RARC, &raw);
 202         if (err)
 203                 return err;
 204         /* Relative capacity is displayed with resolution 0.5 % */
 205         *capacity = raw/2 ;
 206         return 0;
 207 }
 208
 209 static int ds278x_get_status(struct ds278x_info *info, int *status)
 210 {
 211         int err;
 212         int current_uA;
 213         int capacity;
 214
 215         err = info->ops->get_battery_current(info, &current_uA);
 216         if (err)
 217                 return err;
 218
 219         err = info->ops->get_battery_capacity(info, &capacity);
 220         if (err)
 221                 return err;
 222
 223         if (capacity == 100)
 224                 *status = POWER_SUPPLY_STATUS_FULL;
 225         else if (current_uA == 0)
 226                 *status = POWER_SUPPLY_STATUS_NOT_CHARGING;
 227         else if (current_uA < 0)
 228                 *status = POWER_SUPPLY_STATUS_DISCHARGING;
 229         else
 230                 *status = POWER_SUPPLY_STATUS_CHARGING;
 231
 232         return 0;
 233 }
 234
 235 static int ds278x_battery_get_property(struct power_supply *psy,
 236                                        enum power_supply_property prop,
 237                                        union power_supply_propval *val)
 238 {
 239         struct ds278x_info *info = to_ds278x_info(psy);
 240         int ret;
 241
 242         switch (prop) {
 243         case POWER_SUPPLY_PROP_STATUS:
 244                 ret = ds278x_get_status(info, &val->intval);
 245                 break;
 246
 247         case POWER_SUPPLY_PROP_CAPACITY:
 248                 ret = info->ops->get_battery_capacity(info, &val->intval);
 249                 break;
 250
 251         case POWER_SUPPLY_PROP_VOLTAGE_NOW:
 252                 ret = info->ops->get_battery_voltage(info, &val->intval);
 253                 break;
 254
 255         case POWER_SUPPLY_PROP_CURRENT_NOW:
 256                 ret = info->ops->get_battery_current(info, &val->intval);
 257                 break;
 258
 259         case POWER_SUPPLY_PROP_TEMP:
 260                 ret = ds278x_get_temp(info, &val->intval);
 261                 break;
 262
 263         default:
 264                 ret = -EINVAL;
 265         }
 266
 267         return ret;
 268 }
 269
 270 static enum power_supply_property ds278x_battery_props[] = {
 271         POWER_SUPPLY_PROP_STATUS,
 272         POWER_SUPPLY_PROP_CAPACITY,
 273         POWER_SUPPLY_PROP_VOLTAGE_NOW,
 274         POWER_SUPPLY_PROP_CURRENT_NOW,
 275         POWER_SUPPLY_PROP_TEMP,
 276 };
 277
 278 static void ds278x_power_supply_init(struct power_supply *battery)
 279 {
 280         battery->type                   = POWER_SUPPLY_TYPE_BATTERY;
 281         battery->properties             = ds278x_battery_props;
 282         battery->num_properties         = ARRAY_SIZE(ds278x_battery_props);
 283         battery->get_property           = ds278x_battery_get_property;
 284         battery->external_power_changed = NULL;
 285 }
 286
 287 static int ds278x_battery_remove(struct i2c_client *client)
 288 {
 289         struct ds278x_info *info = i2c_get_clientdata(client);
 290
 291         power_supply_unregister(&info->battery);
 292         kfree(info->battery.name);
 293
 294         mutex_lock(&battery_lock);
 295         idr_remove(&battery_id, info->id);
 296         mutex_unlock(&battery_lock);
 297
 298         kfree(info);
 299         return 0;
 300 }
 301
 302 enum ds278x_num_id {
 303         DS2782 = 0,
 304         DS2786,
 305 };
 306
 307 static struct ds278x_battery_ops ds278x_ops[] = {
 308         [DS2782] = {
 309                 .get_battery_current  = ds2782_get_current,
 310                 .get_battery_voltage  = ds2782_get_voltage,
 311                 .get_battery_capacity = ds2782_get_capacity,
 312         },
 313         [DS2786] = {
 314                 .get_battery_current  = ds2786_get_current,
 315                 .get_battery_voltage  = ds2786_get_voltage,
 316                 .get_battery_capacity = ds2786_get_capacity,
 317         }
 318 };
 319
 320 static int ds278x_battery_probe(struct i2c_client *client,
 321                                 const struct i2c_device_id *id)
 322 {
 323         struct ds278x_platform_data *pdata = client->dev.platform_data;
 324         struct ds278x_info *info;
 325         int ret;
 326         int num;
 327
 328         /*
 329          * ds2786 should have the sense resistor value set
 330          * in the platform data
 331          */
 332         if (id->driver_data == DS2786 && !pdata) {
 333                 dev_err(&client->dev, "missing platform data for ds2786\n");
 334                 return -EINVAL;
 335         }
 336
 337         /* Get an ID for this battery */
 338         ret = idr_pre_get(&battery_id, GFP_KERNEL);
 339         if (ret == 0) {
 340                 ret = -ENOMEM;
 341                 goto fail_id;
 342         }
 343
 344         mutex_lock(&battery_lock);
 345         ret = idr_get_new(&battery_id, client, &num);
 346         mutex_unlock(&battery_lock);
 347         if (ret < 0)
 348                 goto fail_id;
 349
 350         info = kzalloc(sizeof(*info), GFP_KERNEL);
 351         if (!info) {
 352                 ret = -ENOMEM;
 353                 goto fail_info;
 354         }
 355
 356         info->battery.name = kasprintf(GFP_KERNEL, "%s-%d", client->name, num);
 357         if (!info->battery.name) {
 358                 ret = -ENOMEM;
 359                 goto fail_name;
 360         }
 361
 362         if (id->driver_data == DS2786)
 363                 info->rsns = pdata->rsns;
 364
 365         i2c_set_clientdata(client, info);
 366         info->client = client;
 367         info->id = num;
 368         info->ops  = &ds278x_ops[id->driver_data];
 369         ds278x_power_supply_init(&info->battery);
 370
 371         ret = power_supply_register(&client->dev, &info->battery);
 372         if (ret) {
 373                 dev_err(&client->dev, "failed to register battery\n");
 374                 goto fail_register;
 375         }
 376
 377         return 0;
 378
 379 fail_register:
 380         kfree(info->battery.name);
 381 fail_name:
 382         kfree(info);
 383 fail_info:
 384         mutex_lock(&battery_lock);
 385         idr_remove(&battery_id, num);
 386         mutex_unlock(&battery_lock);
 387 fail_id:
 388         return ret;
 389 }
 390
 391 static const struct i2c_device_id ds278x_id[] = {
 392         {"ds2782", DS2782},
 393         {"ds2786", DS2786},
 394         {},
 395 };
 396
 397 static struct i2c_driver ds278x_battery_driver = {
 398         .driver         = {
 399                 .name   = "ds2782-battery",
 400         },
 401         .probe          = ds278x_battery_probe,
 402         .remove         = ds278x_battery_remove,
 403         .id_table       = ds278x_id,
 404 };
 405
 406 static int __init ds278x_init(void)
 407 {
 408         return i2c_add_driver(&ds278x_battery_driver);
 409 }
 410 module_init(ds278x_init);
 411
 412 static void __exit ds278x_exit(void)
 413 {
 414         i2c_del_driver(&ds278x_battery_driver);
 415 }
 416 module_exit(ds278x_exit);
 417
 418 MODULE_AUTHOR("Ryan Mallon <ryan@bluewatersys.com>");
 419 MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauage IC driver");
 420 MODULE_LICENSE("GPL");