linux/drivers/power/rx51_battery.c
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   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
  28struct 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 */
  36static 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
  46        if (twl4030_madc_conversion(&req) <= 0)
  47                return -ENODATA;
  48
  49        return req.rbuf[channel];
  50}
  51
  52/*
  53 * Read ADCIN channel 12 (voltage) and convert RAW value to micro voltage
  54 * This conversion formula was extracted from maemo program bsi-read
  55 */
  56static int rx51_battery_read_voltage(struct rx51_device_info *di)
  57{
  58        int voltage = rx51_battery_read_adc(12);
  59
  60        if (voltage < 0)
  61                return voltage;
  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 */
  80static 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
  92static 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 */
 106static 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(0);
 111
 112        /* Zero and negative values are undefined */
 113        if (raw <= 0)
 114                return INT_MAX;
 115
 116        /* ADC channels are 10 bit, higher value are undefined */
 117        if (raw >= (1 << 10))
 118                return INT_MIN;
 119
 120        /* First check for temperature in first direct table */
 121        if (raw < ARRAY_SIZE(rx51_temp_table1))
 122                return rx51_temp_table1[raw] * 100;
 123
 124        /* Binary search RAW value in second inverse table */
 125        while (max - min > 1) {
 126                int mid = (max + min) / 2;
 127                if (rx51_temp_table2[mid] <= raw)
 128                        min = mid;
 129                else if (rx51_temp_table2[mid] > raw)
 130                        max = mid;
 131                if (rx51_temp_table2[mid] == raw)
 132                        break;
 133        }
 134
 135        return (rx51_temp_table2_first - min) * 100;
 136}
 137
 138/*
 139 * Read ADCIN channel 4 (BSI) and convert RAW value to micro Ah
 140 * This conversion formula was extracted from maemo program bsi-read
 141 */
 142static int rx51_battery_read_capacity(struct rx51_device_info *di)
 143{
 144        int capacity = rx51_battery_read_adc(4);
 145
 146        if (capacity < 0)
 147                return capacity;
 148
 149        return 1280 * (1200 * capacity)/(1024 - capacity);
 150}
 151
 152/*
 153 * Return power_supply property
 154 */
 155static int rx51_battery_get_property(struct power_supply *psy,
 156                                        enum power_supply_property psp,
 157                                        union power_supply_propval *val)
 158{
 159        struct rx51_device_info *di = container_of((psy),
 160                                struct rx51_device_info, bat);
 161
 162        switch (psp) {
 163        case POWER_SUPPLY_PROP_TECHNOLOGY:
 164                val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
 165                break;
 166        case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
 167                val->intval = 4200000;
 168                break;
 169        case POWER_SUPPLY_PROP_PRESENT:
 170                val->intval = rx51_battery_read_voltage(di) ? 1 : 0;
 171                break;
 172        case POWER_SUPPLY_PROP_VOLTAGE_NOW:
 173                val->intval = rx51_battery_read_voltage(di);
 174                break;
 175        case POWER_SUPPLY_PROP_TEMP:
 176                val->intval = rx51_battery_read_temperature(di);
 177                break;
 178        case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
 179                val->intval = rx51_battery_read_capacity(di);
 180                break;
 181        default:
 182                return -EINVAL;
 183        }
 184
 185        if (val->intval == INT_MAX || val->intval == INT_MIN)
 186                return -EINVAL;
 187
 188        return 0;
 189}
 190
 191static enum power_supply_property rx51_battery_props[] = {
 192        POWER_SUPPLY_PROP_TECHNOLOGY,
 193        POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
 194        POWER_SUPPLY_PROP_PRESENT,
 195        POWER_SUPPLY_PROP_VOLTAGE_NOW,
 196        POWER_SUPPLY_PROP_TEMP,
 197        POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
 198};
 199
 200static int rx51_battery_probe(struct platform_device *pdev)
 201{
 202        struct rx51_device_info *di;
 203        int ret;
 204
 205        di = kzalloc(sizeof(*di), GFP_KERNEL);
 206        if (!di)
 207                return -ENOMEM;
 208
 209        platform_set_drvdata(pdev, di);
 210
 211        di->bat.name = dev_name(&pdev->dev);
 212        di->bat.type = POWER_SUPPLY_TYPE_BATTERY;
 213        di->bat.properties = rx51_battery_props;
 214        di->bat.num_properties = ARRAY_SIZE(rx51_battery_props);
 215        di->bat.get_property = rx51_battery_get_property;
 216
 217        ret = power_supply_register(di->dev, &di->bat);
 218        if (ret) {
 219                platform_set_drvdata(pdev, NULL);
 220                kfree(di);
 221                return ret;
 222        }
 223
 224        return 0;
 225}
 226
 227static int rx51_battery_remove(struct platform_device *pdev)
 228{
 229        struct rx51_device_info *di = platform_get_drvdata(pdev);
 230
 231        power_supply_unregister(&di->bat);
 232        platform_set_drvdata(pdev, NULL);
 233        kfree(di);
 234
 235        return 0;
 236}
 237
 238static struct platform_driver rx51_battery_driver = {
 239        .probe = rx51_battery_probe,
 240        .remove = rx51_battery_remove,
 241        .driver = {
 242                .name = "rx51-battery",
 243                .owner = THIS_MODULE,
 244        },
 245};
 246module_platform_driver(rx51_battery_driver);
 247
 248MODULE_ALIAS("platform:rx51-battery");
 249MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
 250MODULE_DESCRIPTION("Nokia RX-51 battery driver");
 251MODULE_LICENSE("GPL");
 252
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