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