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        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 */
  57static 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 */
  81static 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
  93static 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 */
 107static 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 */
 143static 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 */
 156static 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
 192static 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
 201static 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
 225static 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
 234static 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};
 242module_platform_driver(rx51_battery_driver);
 243
 244MODULE_ALIAS("platform:rx51-battery");
 245MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
 246MODULE_DESCRIPTION("Nokia RX-51 battery driver");
 247MODULE_LICENSE("GPL");
 248
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