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Linux/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                 .owner = THIS_MODULE,
285                 .of_match_table = of_match_ptr(n900_battery_of_match),
286         },
287 };
288 module_platform_driver(rx51_battery_driver);
289 
290 MODULE_ALIAS("platform:rx51-battery");
291 MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
292 MODULE_DESCRIPTION("Nokia RX-51 battery driver");
293 MODULE_LICENSE("GPL");
294 

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