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/iio/consumer.h>
27 #include <linux/of.h>
28
29 struct rx51_device_info {
30 struct device *dev;
31 struct power_supply *bat;
32 struct power_supply_desc bat_desc;
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 */
rx51_battery_read_adc(struct iio_channel * channel)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 */
rx51_battery_read_voltage(struct rx51_device_info * di)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 */
rx51_battery_read_temperature(struct rx51_device_info * di)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 */
rx51_battery_read_capacity(struct rx51_device_info * di)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 */
rx51_battery_get_property(struct power_supply * psy,enum power_supply_property psp,union power_supply_propval * val)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 = power_supply_get_drvdata(psy);
165
166 switch (psp) {
167 case POWER_SUPPLY_PROP_TECHNOLOGY:
168 val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
169 break;
170 case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
171 val->intval = 4200000;
172 break;
173 case POWER_SUPPLY_PROP_PRESENT:
174 val->intval = rx51_battery_read_voltage(di) ? 1 : 0;
175 break;
176 case POWER_SUPPLY_PROP_VOLTAGE_NOW:
177 val->intval = rx51_battery_read_voltage(di);
178 break;
179 case POWER_SUPPLY_PROP_TEMP:
180 val->intval = rx51_battery_read_temperature(di);
181 break;
182 case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
183 val->intval = rx51_battery_read_capacity(di);
184 break;
185 default:
186 return -EINVAL;
187 }
188
189 if (val->intval == INT_MAX || val->intval == INT_MIN)
190 return -EINVAL;
191
192 return 0;
193 }
194
195 static enum power_supply_property rx51_battery_props[] = {
196 POWER_SUPPLY_PROP_TECHNOLOGY,
197 POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
198 POWER_SUPPLY_PROP_PRESENT,
199 POWER_SUPPLY_PROP_VOLTAGE_NOW,
200 POWER_SUPPLY_PROP_TEMP,
201 POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
202 };
203
rx51_battery_probe(struct platform_device * pdev)204 static int rx51_battery_probe(struct platform_device *pdev)
205 {
206 struct power_supply_config psy_cfg = {};
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_desc.name = "rx51-battery";
218 di->bat_desc.type = POWER_SUPPLY_TYPE_BATTERY;
219 di->bat_desc.properties = rx51_battery_props;
220 di->bat_desc.num_properties = ARRAY_SIZE(rx51_battery_props);
221 di->bat_desc.get_property = rx51_battery_get_property;
222
223 psy_cfg.drv_data = di;
224
225 di->channel_temp = iio_channel_get(di->dev, "temp");
226 if (IS_ERR(di->channel_temp)) {
227 ret = PTR_ERR(di->channel_temp);
228 goto error;
229 }
230
231 di->channel_bsi = iio_channel_get(di->dev, "bsi");
232 if (IS_ERR(di->channel_bsi)) {
233 ret = PTR_ERR(di->channel_bsi);
234 goto error_channel_temp;
235 }
236
237 di->channel_vbat = iio_channel_get(di->dev, "vbat");
238 if (IS_ERR(di->channel_vbat)) {
239 ret = PTR_ERR(di->channel_vbat);
240 goto error_channel_bsi;
241 }
242
243 di->bat = power_supply_register(di->dev, &di->bat_desc, &psy_cfg);
244 if (IS_ERR(di->bat)) {
245 ret = PTR_ERR(di->bat);
246 goto error_channel_vbat;
247 }
248
249 return 0;
250
251 error_channel_vbat:
252 iio_channel_release(di->channel_vbat);
253 error_channel_bsi:
254 iio_channel_release(di->channel_bsi);
255 error_channel_temp:
256 iio_channel_release(di->channel_temp);
257 error:
258
259 return ret;
260 }
261
rx51_battery_remove(struct platform_device * pdev)262 static int rx51_battery_remove(struct platform_device *pdev)
263 {
264 struct rx51_device_info *di = platform_get_drvdata(pdev);
265
266 power_supply_unregister(di->bat);
267
268 iio_channel_release(di->channel_vbat);
269 iio_channel_release(di->channel_bsi);
270 iio_channel_release(di->channel_temp);
271
272 return 0;
273 }
274
275 #ifdef CONFIG_OF
276 static const struct of_device_id n900_battery_of_match[] = {
277 {.compatible = "nokia,n900-battery", },
278 { },
279 };
280 MODULE_DEVICE_TABLE(of, n900_battery_of_match);
281 #endif
282
283 static struct platform_driver rx51_battery_driver = {
284 .probe = rx51_battery_probe,
285 .remove = rx51_battery_remove,
286 .driver = {
287 .name = "rx51-battery",
288 .of_match_table = of_match_ptr(n900_battery_of_match),
289 },
290 };
291 module_platform_driver(rx51_battery_driver);
292
293 MODULE_ALIAS("platform:rx51-battery");
294 MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
295 MODULE_DESCRIPTION("Nokia RX-51 battery driver");
296 MODULE_LICENSE("GPL");
297
