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
  28 struct rx51_device_info {
  29         struct device *dev;
  30         struct power_supply bat;
  31 };
  32
  33 /*
  34  * Read ADCIN channel value, code copied from maemo kernel
  35  */
  36 static int rx51_battery_read_adc(int channel)
  37 {
  38         struct twl4030_madc_request req;
  39
  40         req.channels = 1 << channel;
  41         req.do_avg = 1;
  42         req.method = TWL4030_MADC_SW1;
  43         req.func_cb = NULL;
  44         req.type = TWL4030_MADC_WAIT;
  45         req.raw = true;
  46
  47         if (twl4030_madc_conversion(&req) <= 0)
  48                 return -ENODATA;
  49
  50         return req.rbuf[channel];
  51 }
  52
  53 /*
  54  * Read ADCIN channel 12 (voltage) and convert RAW value to micro voltage
  55  * This conversion formula was extracted from maemo program bsi-read
  56  */
  57 static int rx51_battery_read_voltage(struct rx51_device_info *di)
  58 {
  59         int voltage = rx51_battery_read_adc(12);
  60
  61         if (voltage < 0)
  62                 return voltage;
  63
  64         return 1000 * (10000 * voltage / 1705);
  65 }
  66
  67 /*
  68  * Temperature look-up tables
  69  * TEMP = (1/(t1 + 1/298) - 273.15)
  70  * Where t1 = (1/B) * ln((RAW_ADC_U * 2.5)/(R * I * 255))
  71  * Formula is based on experimental data, RX-51 CAL data, maemo program bme
  72  * and formula from da9052 driver with values R = 100, B = 3380, I = 0.00671
  73  */
  74
  75 /*
  76  * Table1 (temperature for first 25 RAW values)
  77  * Usage: TEMP = rx51_temp_table1[RAW]
  78  *   RAW is between 1 and 24
  79  *   TEMP is between 201 C and 55 C
  80  */
  81 static u8 rx51_temp_table1[] = {
  82         255, 201, 159, 138, 124, 114, 106,  99,  94,  89,  85,  82,  78,  75,
  83          73,  70,  68,  66,  64,  62,  61,  59,  57,  56,  55
  84 };
  85
  86 /*
  87  * Table2 (lowest RAW value for temperature)
  88  * Usage: RAW = rx51_temp_table2[TEMP-rx51_temp_table2_first]
  89  *   TEMP is between 53 C and -32 C
  90  *   RAW is between 25 and 993
  91  */
  92 #define rx51_temp_table2_first 53
  93 static u16 rx51_temp_table2[] = {
  94          25,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35,  36,  37,  39,
  95          40,  41,  43,  44,  46,  48,  49,  51,  53,  55,  57,  59,  61,  64,
  96          66,  69,  71,  74,  77,  80,  83,  86,  90,  94,  97, 101, 106, 110,
  97         115, 119, 125, 130, 136, 141, 148, 154, 161, 168, 176, 184, 202, 211,
  98         221, 231, 242, 254, 266, 279, 293, 308, 323, 340, 357, 375, 395, 415,
  99         437, 460, 485, 511, 539, 568, 600, 633, 669, 706, 747, 790, 836, 885,
 100         937, 993, 1024
 101 };
 102
 103 /*
 104  * Read ADCIN channel 0 (battery temp) and convert value to tenths of Celsius
 105  * Use Temperature look-up tables for conversation
 106  */
 107 static int rx51_battery_read_temperature(struct rx51_device_info *di)
 108 {
 109         int min = 0;
 110         int max = ARRAY_SIZE(rx51_temp_table2) - 1;
 111         int raw = rx51_battery_read_adc(0);
 112
 113         /* Zero and negative values are undefined */
 114         if (raw <= 0)
 115                 return INT_MAX;
 116
 117         /* ADC channels are 10 bit, higher value are undefined */
 118         if (raw >= (1 << 10))
 119                 return INT_MIN;
 120
 121         /* First check for temperature in first direct table */
 122         if (raw < ARRAY_SIZE(rx51_temp_table1))
 123                 return rx51_temp_table1[raw] * 10;
 124
 125         /* Binary search RAW value in second inverse table */
 126         while (max - min > 1) {
 127                 int mid = (max + min) / 2;
 128                 if (rx51_temp_table2[mid] <= raw)
 129                         min = mid;
 130                 else if (rx51_temp_table2[mid] > raw)
 131                         max = mid;
 132                 if (rx51_temp_table2[mid] == raw)
 133                         break;
 134         }
 135
 136         return (rx51_temp_table2_first - min) * 10;
 137 }
 138
 139 /*
 140  * Read ADCIN channel 4 (BSI) and convert RAW value to micro Ah
 141  * This conversion formula was extracted from maemo program bsi-read
 142  */
 143 static int rx51_battery_read_capacity(struct rx51_device_info *di)
 144 {
 145         int capacity = rx51_battery_read_adc(4);
 146
 147         if (capacity < 0)
 148                 return capacity;
 149
 150         return 1280 * (1200 * capacity)/(1024 - capacity);
 151 }
 152
 153 /*
 154  * Return power_supply property
 155  */
 156 static int rx51_battery_get_property(struct power_supply *psy,
 157                                         enum power_supply_property psp,
 158                                         union power_supply_propval *val)
 159 {
 160         struct rx51_device_info *di = container_of((psy),
 161                                 struct rx51_device_info, bat);
 162
 163         switch (psp) {
 164         case POWER_SUPPLY_PROP_TECHNOLOGY:
 165                 val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
 166                 break;
 167         case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
 168                 val->intval = 4200000;
 169                 break;
 170         case POWER_SUPPLY_PROP_PRESENT:
 171                 val->intval = rx51_battery_read_voltage(di) ? 1 : 0;
 172                 break;
 173         case POWER_SUPPLY_PROP_VOLTAGE_NOW:
 174                 val->intval = rx51_battery_read_voltage(di);
 175                 break;
 176         case POWER_SUPPLY_PROP_TEMP:
 177                 val->intval = rx51_battery_read_temperature(di);
 178                 break;
 179         case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
 180                 val->intval = rx51_battery_read_capacity(di);
 181                 break;
 182         default:
 183                 return -EINVAL;
 184         }
 185
 186         if (val->intval == INT_MAX || val->intval == INT_MIN)
 187                 return -EINVAL;
 188
 189         return 0;
 190 }
 191
 192 static enum power_supply_property rx51_battery_props[] = {
 193         POWER_SUPPLY_PROP_TECHNOLOGY,
 194         POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
 195         POWER_SUPPLY_PROP_PRESENT,
 196         POWER_SUPPLY_PROP_VOLTAGE_NOW,
 197         POWER_SUPPLY_PROP_TEMP,
 198         POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
 199 };
 200
 201 static int rx51_battery_probe(struct platform_device *pdev)
 202 {
 203         struct rx51_device_info *di;
 204         int ret;
 205
 206         di = devm_kzalloc(&pdev->dev, sizeof(*di), GFP_KERNEL);
 207         if (!di)
 208                 return -ENOMEM;
 209
 210         platform_set_drvdata(pdev, di);
 211
 212         di->bat.name = dev_name(&pdev->dev);
 213         di->bat.type = POWER_SUPPLY_TYPE_BATTERY;
 214         di->bat.properties = rx51_battery_props;
 215         di->bat.num_properties = ARRAY_SIZE(rx51_battery_props);
 216         di->bat.get_property = rx51_battery_get_property;
 217
 218         ret = power_supply_register(di->dev, &di->bat);
 219         if (ret)
 220                 return ret;
 221
 222         return 0;
 223 }
 224
 225 static int rx51_battery_remove(struct platform_device *pdev)
 226 {
 227         struct rx51_device_info *di = platform_get_drvdata(pdev);
 228
 229         power_supply_unregister(&di->bat);
 230
 231         return 0;
 232 }
 233
 234 static struct platform_driver rx51_battery_driver = {
 235         .probe = rx51_battery_probe,
 236         .remove = rx51_battery_remove,
 237         .driver = {
 238                 .name = "rx51-battery",
 239                 .owner = THIS_MODULE,
 240         },
 241 };
 242 module_platform_driver(rx51_battery_driver);
 243
 244 MODULE_ALIAS("platform:rx51-battery");
 245 MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
 246 MODULE_DESCRIPTION("Nokia RX-51 battery driver");
 247 MODULE_LICENSE("GPL");