drivers/power/rx51_battery.c

   1 /*
   2  * Nokia RX-51 battery driver
   3  *
   4  * Copyright (C) 2012  Pali Rohár <pali.rohar@gmail.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/param.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/power_supply.h>
  25 #include <linux/slab.h>
  26 #include <linux/i2c/twl4030-madc.h>
  27 #include <linux/iio/consumer.h>
  28 #include <linux/of.h>
  29
  30 struct rx51_device_info {
  31         struct device *dev;
  32         struct power_supply bat;
  33         struct iio_channel *channel_temp;
  34         struct iio_channel *channel_bsi;
  35         struct iio_channel *channel_vbat;
  36 };
  37
  38 /*
  39  * Read ADCIN channel value, code copied from maemo kernel
  40  */
  41 static int rx51_battery_read_adc(struct iio_channel *channel)
  42 {
  43         int val, err;
  44         err = iio_read_channel_average_raw(channel, &val);
  45         if (err < 0)
  46                 return err;
  47         return val;
  48 }
  49
  50 /*
  51  * Read ADCIN channel 12 (voltage) and convert RAW value to micro voltage
  52  * This conversion formula was extracted from maemo program bsi-read
  53  */
  54 static int rx51_battery_read_voltage(struct rx51_device_info *di)
  55 {
  56         int voltage = rx51_battery_read_adc(di->channel_vbat);
  57
  58         if (voltage < 0) {
  59                 dev_err(di->dev, "Could not read ADC: %d\n", voltage);
  60                 return voltage;
  61         }
  62
  63         return 1000 * (10000 * voltage / 1705);
  64 }
  65
  66 /*
  67  * Temperature look-up tables
  68  * TEMP = (1/(t1 + 1/298) - 273.15)
  69  * Where t1 = (1/B) * ln((RAW_ADC_U * 2.5)/(R * I * 255))
  70  * Formula is based on experimental data, RX-51 CAL data, maemo program bme
  71  * and formula from da9052 driver with values R = 100, B = 3380, I = 0.00671
  72  */
  73
  74 /*
  75  * Table1 (temperature for first 25 RAW values)
  76  * Usage: TEMP = rx51_temp_table1[RAW]
  77  *   RAW is between 1 and 24
  78  *   TEMP is between 201 C and 55 C
  79  */
  80 static u8 rx51_temp_table1[] = {
  81         255, 201, 159, 138, 124, 114, 106,  99,  94,  89,  85,  82,  78,  75,
  82          73,  70,  68,  66,  64,  62,  61,  59,  57,  56,  55
  83 };
  84
  85 /*
  86  * Table2 (lowest RAW value for temperature)
  87  * Usage: RAW = rx51_temp_table2[TEMP-rx51_temp_table2_first]
  88  *   TEMP is between 53 C and -32 C
  89  *   RAW is between 25 and 993
  90  */
  91 #define rx51_temp_table2_first 53
  92 static u16 rx51_temp_table2[] = {
  93          25,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35,  36,  37,  39,
  94          40,  41,  43,  44,  46,  48,  49,  51,  53,  55,  57,  59,  61,  64,
  95          66,  69,  71,  74,  77,  80,  83,  86,  90,  94,  97, 101, 106, 110,
  96         115, 119, 125, 130, 136, 141, 148, 154, 161, 168, 176, 184, 202, 211,
  97         221, 231, 242, 254, 266, 279, 293, 308, 323, 340, 357, 375, 395, 415,
  98         437, 460, 485, 511, 539, 568, 600, 633, 669, 706, 747, 790, 836, 885,
  99         937, 993, 1024
 100 };
 101
 102 /*
 103  * Read ADCIN channel 0 (battery temp) and convert value to tenths of Celsius
 104  * Use Temperature look-up tables for conversation
 105  */
 106 static int rx51_battery_read_temperature(struct rx51_device_info *di)
 107 {
 108         int min = 0;
 109         int max = ARRAY_SIZE(rx51_temp_table2) - 1;
 110         int raw = rx51_battery_read_adc(di->channel_temp);
 111
 112         if (raw < 0)
 113                 dev_err(di->dev, "Could not read ADC: %d\n", raw);
 114
 115         /* Zero and negative values are undefined */
 116         if (raw <= 0)
 117                 return INT_MAX;
 118
 119         /* ADC channels are 10 bit, higher value are undefined */
 120         if (raw >= (1 << 10))
 121                 return INT_MIN;
 122
 123         /* First check for temperature in first direct table */
 124         if (raw < ARRAY_SIZE(rx51_temp_table1))
 125                 return rx51_temp_table1[raw] * 10;
 126
 127         /* Binary search RAW value in second inverse table */
 128         while (max - min > 1) {
 129                 int mid = (max + min) / 2;
 130                 if (rx51_temp_table2[mid] <= raw)
 131                         min = mid;
 132                 else if (rx51_temp_table2[mid] > raw)
 133                         max = mid;
 134                 if (rx51_temp_table2[mid] == raw)
 135                         break;
 136         }
 137
 138         return (rx51_temp_table2_first - min) * 10;
 139 }
 140
 141 /*
 142  * Read ADCIN channel 4 (BSI) and convert RAW value to micro Ah
 143  * This conversion formula was extracted from maemo program bsi-read
 144  */
 145 static int rx51_battery_read_capacity(struct rx51_device_info *di)
 146 {
 147         int capacity = rx51_battery_read_adc(di->channel_bsi);
 148
 149         if (capacity < 0) {
 150                 dev_err(di->dev, "Could not read ADC: %d\n", capacity);
 151                 return capacity;
 152         }
 153
 154         return 1280 * (1200 * capacity)/(1024 - capacity);
 155 }
 156
 157 /*
 158  * Return power_supply property
 159  */
 160 static int rx51_battery_get_property(struct power_supply *psy,
 161                                         enum power_supply_property psp,
 162                                         union power_supply_propval *val)
 163 {
 164         struct rx51_device_info *di = container_of((psy),
 165                                 struct rx51_device_info, bat);
 166
 167         switch (psp) {
 168         case POWER_SUPPLY_PROP_TECHNOLOGY:
 169                 val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
 170                 break;
 171         case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
 172                 val->intval = 4200000;
 173                 break;
 174         case POWER_SUPPLY_PROP_PRESENT:
 175                 val->intval = rx51_battery_read_voltage(di) ? 1 : 0;
 176                 break;
 177         case POWER_SUPPLY_PROP_VOLTAGE_NOW:
 178                 val->intval = rx51_battery_read_voltage(di);
 179                 break;
 180         case POWER_SUPPLY_PROP_TEMP:
 181                 val->intval = rx51_battery_read_temperature(di);
 182                 break;
 183         case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
 184                 val->intval = rx51_battery_read_capacity(di);
 185                 break;
 186         default:
 187                 return -EINVAL;
 188         }
 189
 190         if (val->intval == INT_MAX || val->intval == INT_MIN)
 191                 return -EINVAL;
 192
 193         return 0;
 194 }
 195
 196 static enum power_supply_property rx51_battery_props[] = {
 197         POWER_SUPPLY_PROP_TECHNOLOGY,
 198         POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
 199         POWER_SUPPLY_PROP_PRESENT,
 200         POWER_SUPPLY_PROP_VOLTAGE_NOW,
 201         POWER_SUPPLY_PROP_TEMP,
 202         POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
 203 };
 204
 205 static int rx51_battery_probe(struct platform_device *pdev)
 206 {
 207         struct rx51_device_info *di;
 208         int ret;
 209
 210         di = devm_kzalloc(&pdev->dev, sizeof(*di), GFP_KERNEL);
 211         if (!di)
 212                 return -ENOMEM;
 213
 214         platform_set_drvdata(pdev, di);
 215
 216         di->dev = &pdev->dev;
 217         di->bat.name = dev_name(&pdev->dev);
 218         di->bat.type = POWER_SUPPLY_TYPE_BATTERY;
 219         di->bat.properties = rx51_battery_props;
 220         di->bat.num_properties = ARRAY_SIZE(rx51_battery_props);
 221         di->bat.get_property = rx51_battery_get_property;
 222
 223         di->channel_temp = iio_channel_get(di->dev, "temp");
 224         if (IS_ERR(di->channel_temp)) {
 225                 ret = PTR_ERR(di->channel_temp);
 226                 goto error;
 227         }
 228
 229         di->channel_bsi  = iio_channel_get(di->dev, "bsi");
 230         if (IS_ERR(di->channel_bsi)) {
 231                 ret = PTR_ERR(di->channel_bsi);
 232                 goto error_channel_temp;
 233         }
 234
 235         di->channel_vbat = iio_channel_get(di->dev, "vbat");
 236         if (IS_ERR(di->channel_vbat)) {
 237                 ret = PTR_ERR(di->channel_vbat);
 238                 goto error_channel_bsi;
 239         }
 240
 241         ret = power_supply_register(di->dev, &di->bat);
 242         if (ret)
 243                 goto error_channel_vbat;
 244
 245         return 0;
 246
 247 error_channel_vbat:
 248         iio_channel_release(di->channel_vbat);
 249 error_channel_bsi:
 250         iio_channel_release(di->channel_bsi);
 251 error_channel_temp:
 252         iio_channel_release(di->channel_temp);
 253 error:
 254
 255         return ret;
 256 }
 257
 258 static int rx51_battery_remove(struct platform_device *pdev)
 259 {
 260         struct rx51_device_info *di = platform_get_drvdata(pdev);
 261
 262         power_supply_unregister(&di->bat);
 263
 264         iio_channel_release(di->channel_vbat);
 265         iio_channel_release(di->channel_bsi);
 266         iio_channel_release(di->channel_temp);
 267
 268         return 0;
 269 }
 270
 271 #ifdef CONFIG_OF
 272 static const struct of_device_id n900_battery_of_match[] = {
 273         {.compatible = "nokia,n900-battery", },
 274         { },
 275 };
 276 MODULE_DEVICE_TABLE(of, n900_battery_of_match);
 277 #endif
 278
 279 static struct platform_driver rx51_battery_driver = {
 280         .probe = rx51_battery_probe,
 281         .remove = rx51_battery_remove,
 282         .driver = {
 283                 .name = "rx51-battery",
 284                 .of_match_table = of_match_ptr(n900_battery_of_match),
 285         },
 286 };
 287 module_platform_driver(rx51_battery_driver);
 288
 289 MODULE_ALIAS("platform:rx51-battery");
 290 MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
 291 MODULE_DESCRIPTION("Nokia RX-51 battery driver");
 292 MODULE_LICENSE("GPL");