1 /*
2 * I2C client/driver for the Maxim/Dallas DS2782 Stand-Alone Fuel Gauge IC
3 *
4 * Copyright (C) 2009 Bluewater Systems Ltd
5 *
6 * Author: Ryan Mallon
7 *
8 * DS2786 added by Yulia Vilensky <vilensky@compulab.co.il>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 *
14 */
15
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/types.h>
19 #include <linux/errno.h>
20 #include <linux/swab.h>
21 #include <linux/i2c.h>
22 #include <linux/idr.h>
23 #include <linux/power_supply.h>
24 #include <linux/slab.h>
25 #include <linux/ds2782_battery.h>
26
27 #define DS2782_REG_RARC 0x06 /* Remaining active relative capacity */
28
29 #define DS278x_REG_VOLT_MSB 0x0c
30 #define DS278x_REG_TEMP_MSB 0x0a
31 #define DS278x_REG_CURRENT_MSB 0x0e
32
33 /* EEPROM Block */
34 #define DS2782_REG_RSNSP 0x69 /* Sense resistor value */
35
36 /* Current unit measurement in uA for a 1 milli-ohm sense resistor */
37 #define DS2782_CURRENT_UNITS 1563
38
39 #define DS2786_REG_RARC 0x02 /* Remaining active relative capacity */
40
41 #define DS2786_CURRENT_UNITS 25
42
43 struct ds278x_info;
44
45 struct ds278x_battery_ops {
46 int (*get_battery_current)(struct ds278x_info *info, int *current_uA);
47 int (*get_battery_voltage)(struct ds278x_info *info, int *voltage_uV);
48 int (*get_battery_capacity)(struct ds278x_info *info, int *capacity);
49 };
50
51 #define to_ds278x_info(x) container_of(x, struct ds278x_info, battery)
52
53 struct ds278x_info {
54 struct i2c_client *client;
55 struct power_supply battery;
56 struct ds278x_battery_ops *ops;
57 int id;
58 int rsns;
59 };
60
61 static DEFINE_IDR(battery_id);
62 static DEFINE_MUTEX(battery_lock);
63
ds278x_read_reg(struct ds278x_info * info,int reg,u8 * val)64 static inline int ds278x_read_reg(struct ds278x_info *info, int reg, u8 *val)
65 {
66 int ret;
67
68 ret = i2c_smbus_read_byte_data(info->client, reg);
69 if (ret < 0) {
70 dev_err(&info->client->dev, "register read failed\n");
71 return ret;
72 }
73
74 *val = ret;
75 return 0;
76 }
77
ds278x_read_reg16(struct ds278x_info * info,int reg_msb,s16 * val)78 static inline int ds278x_read_reg16(struct ds278x_info *info, int reg_msb,
79 s16 *val)
80 {
81 int ret;
82
83 ret = swab16(i2c_smbus_read_word_data(info->client, reg_msb));
84 if (ret < 0) {
85 dev_err(&info->client->dev, "register read failed\n");
86 return ret;
87 }
88
89 *val = ret;
90 return 0;
91 }
92
ds278x_get_temp(struct ds278x_info * info,int * temp)93 static int ds278x_get_temp(struct ds278x_info *info, int *temp)
94 {
95 s16 raw;
96 int err;
97
98 /*
99 * Temperature is measured in units of 0.125 degrees celcius, the
100 * power_supply class measures temperature in tenths of degrees
101 * celsius. The temperature value is stored as a 10 bit number, plus
102 * sign in the upper bits of a 16 bit register.
103 */
104 err = ds278x_read_reg16(info, DS278x_REG_TEMP_MSB, &raw);
105 if (err)
106 return err;
107 *temp = ((raw / 32) * 125) / 100;
108 return 0;
109 }
110
ds2782_get_current(struct ds278x_info * info,int * current_uA)111 static int ds2782_get_current(struct ds278x_info *info, int *current_uA)
112 {
113 int sense_res;
114 int err;
115 u8 sense_res_raw;
116 s16 raw;
117
118 /*
119 * The units of measurement for current are dependent on the value of
120 * the sense resistor.
121 */
122 err = ds278x_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw);
123 if (err)
124 return err;
125 if (sense_res_raw == 0) {
126 dev_err(&info->client->dev, "sense resistor value is 0\n");
127 return -ENXIO;
128 }
129 sense_res = 1000 / sense_res_raw;
130
131 dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n",
132 sense_res);
133 err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
134 if (err)
135 return err;
136 *current_uA = raw * (DS2782_CURRENT_UNITS / sense_res);
137 return 0;
138 }
139
ds2782_get_voltage(struct ds278x_info * info,int * voltage_uV)140 static int ds2782_get_voltage(struct ds278x_info *info, int *voltage_uV)
141 {
142 s16 raw;
143 int err;
144
145 /*
146 * Voltage is measured in units of 4.88mV. The voltage is stored as
147 * a 10-bit number plus sign, in the upper bits of a 16-bit register
148 */
149 err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
150 if (err)
151 return err;
152 *voltage_uV = (raw / 32) * 4800;
153 return 0;
154 }
155
ds2782_get_capacity(struct ds278x_info * info,int * capacity)156 static int ds2782_get_capacity(struct ds278x_info *info, int *capacity)
157 {
158 int err;
159 u8 raw;
160
161 err = ds278x_read_reg(info, DS2782_REG_RARC, &raw);
162 if (err)
163 return err;
164 *capacity = raw;
165 return 0;
166 }
167
ds2786_get_current(struct ds278x_info * info,int * current_uA)168 static int ds2786_get_current(struct ds278x_info *info, int *current_uA)
169 {
170 int err;
171 s16 raw;
172
173 err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
174 if (err)
175 return err;
176 *current_uA = (raw / 16) * (DS2786_CURRENT_UNITS / info->rsns);
177 return 0;
178 }
179
ds2786_get_voltage(struct ds278x_info * info,int * voltage_uV)180 static int ds2786_get_voltage(struct ds278x_info *info, int *voltage_uV)
181 {
182 s16 raw;
183 int err;
184
185 /*
186 * Voltage is measured in units of 1.22mV. The voltage is stored as
187 * a 10-bit number plus sign, in the upper bits of a 16-bit register
188 */
189 err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
190 if (err)
191 return err;
192 *voltage_uV = (raw / 8) * 1220;
193 return 0;
194 }
195
ds2786_get_capacity(struct ds278x_info * info,int * capacity)196 static int ds2786_get_capacity(struct ds278x_info *info, int *capacity)
197 {
198 int err;
199 u8 raw;
200
201 err = ds278x_read_reg(info, DS2786_REG_RARC, &raw);
202 if (err)
203 return err;
204 /* Relative capacity is displayed with resolution 0.5 % */
205 *capacity = raw/2 ;
206 return 0;
207 }
208
ds278x_get_status(struct ds278x_info * info,int * status)209 static int ds278x_get_status(struct ds278x_info *info, int *status)
210 {
211 int err;
212 int current_uA;
213 int capacity;
214
215 err = info->ops->get_battery_current(info, ¤t_uA);
216 if (err)
217 return err;
218
219 err = info->ops->get_battery_capacity(info, &capacity);
220 if (err)
221 return err;
222
223 if (capacity == 100)
224 *status = POWER_SUPPLY_STATUS_FULL;
225 else if (current_uA == 0)
226 *status = POWER_SUPPLY_STATUS_NOT_CHARGING;
227 else if (current_uA < 0)
228 *status = POWER_SUPPLY_STATUS_DISCHARGING;
229 else
230 *status = POWER_SUPPLY_STATUS_CHARGING;
231
232 return 0;
233 }
234
ds278x_battery_get_property(struct power_supply * psy,enum power_supply_property prop,union power_supply_propval * val)235 static int ds278x_battery_get_property(struct power_supply *psy,
236 enum power_supply_property prop,
237 union power_supply_propval *val)
238 {
239 struct ds278x_info *info = to_ds278x_info(psy);
240 int ret;
241
242 switch (prop) {
243 case POWER_SUPPLY_PROP_STATUS:
244 ret = ds278x_get_status(info, &val->intval);
245 break;
246
247 case POWER_SUPPLY_PROP_CAPACITY:
248 ret = info->ops->get_battery_capacity(info, &val->intval);
249 break;
250
251 case POWER_SUPPLY_PROP_VOLTAGE_NOW:
252 ret = info->ops->get_battery_voltage(info, &val->intval);
253 break;
254
255 case POWER_SUPPLY_PROP_CURRENT_NOW:
256 ret = info->ops->get_battery_current(info, &val->intval);
257 break;
258
259 case POWER_SUPPLY_PROP_TEMP:
260 ret = ds278x_get_temp(info, &val->intval);
261 break;
262
263 default:
264 ret = -EINVAL;
265 }
266
267 return ret;
268 }
269
270 static enum power_supply_property ds278x_battery_props[] = {
271 POWER_SUPPLY_PROP_STATUS,
272 POWER_SUPPLY_PROP_CAPACITY,
273 POWER_SUPPLY_PROP_VOLTAGE_NOW,
274 POWER_SUPPLY_PROP_CURRENT_NOW,
275 POWER_SUPPLY_PROP_TEMP,
276 };
277
ds278x_power_supply_init(struct power_supply * battery)278 static void ds278x_power_supply_init(struct power_supply *battery)
279 {
280 battery->type = POWER_SUPPLY_TYPE_BATTERY;
281 battery->properties = ds278x_battery_props;
282 battery->num_properties = ARRAY_SIZE(ds278x_battery_props);
283 battery->get_property = ds278x_battery_get_property;
284 battery->external_power_changed = NULL;
285 }
286
ds278x_battery_remove(struct i2c_client * client)287 static int ds278x_battery_remove(struct i2c_client *client)
288 {
289 struct ds278x_info *info = i2c_get_clientdata(client);
290
291 power_supply_unregister(&info->battery);
292 kfree(info->battery.name);
293
294 mutex_lock(&battery_lock);
295 idr_remove(&battery_id, info->id);
296 mutex_unlock(&battery_lock);
297
298 kfree(info);
299 return 0;
300 }
301
302 enum ds278x_num_id {
303 DS2782 = 0,
304 DS2786,
305 };
306
307 static struct ds278x_battery_ops ds278x_ops[] = {
308 [DS2782] = {
309 .get_battery_current = ds2782_get_current,
310 .get_battery_voltage = ds2782_get_voltage,
311 .get_battery_capacity = ds2782_get_capacity,
312 },
313 [DS2786] = {
314 .get_battery_current = ds2786_get_current,
315 .get_battery_voltage = ds2786_get_voltage,
316 .get_battery_capacity = ds2786_get_capacity,
317 }
318 };
319
ds278x_battery_probe(struct i2c_client * client,const struct i2c_device_id * id)320 static int ds278x_battery_probe(struct i2c_client *client,
321 const struct i2c_device_id *id)
322 {
323 struct ds278x_platform_data *pdata = client->dev.platform_data;
324 struct ds278x_info *info;
325 int ret;
326 int num;
327
328 /*
329 * ds2786 should have the sense resistor value set
330 * in the platform data
331 */
332 if (id->driver_data == DS2786 && !pdata) {
333 dev_err(&client->dev, "missing platform data for ds2786\n");
334 return -EINVAL;
335 }
336
337 /* Get an ID for this battery */
338 ret = idr_pre_get(&battery_id, GFP_KERNEL);
339 if (ret == 0) {
340 ret = -ENOMEM;
341 goto fail_id;
342 }
343
344 mutex_lock(&battery_lock);
345 ret = idr_get_new(&battery_id, client, &num);
346 mutex_unlock(&battery_lock);
347 if (ret < 0)
348 goto fail_id;
349
350 info = kzalloc(sizeof(*info), GFP_KERNEL);
351 if (!info) {
352 ret = -ENOMEM;
353 goto fail_info;
354 }
355
356 info->battery.name = kasprintf(GFP_KERNEL, "%s-%d", client->name, num);
357 if (!info->battery.name) {
358 ret = -ENOMEM;
359 goto fail_name;
360 }
361
362 if (id->driver_data == DS2786)
363 info->rsns = pdata->rsns;
364
365 i2c_set_clientdata(client, info);
366 info->client = client;
367 info->id = num;
368 info->ops = &ds278x_ops[id->driver_data];
369 ds278x_power_supply_init(&info->battery);
370
371 ret = power_supply_register(&client->dev, &info->battery);
372 if (ret) {
373 dev_err(&client->dev, "failed to register battery\n");
374 goto fail_register;
375 }
376
377 return 0;
378
379 fail_register:
380 kfree(info->battery.name);
381 fail_name:
382 kfree(info);
383 fail_info:
384 mutex_lock(&battery_lock);
385 idr_remove(&battery_id, num);
386 mutex_unlock(&battery_lock);
387 fail_id:
388 return ret;
389 }
390
391 static const struct i2c_device_id ds278x_id[] = {
392 {"ds2782", DS2782},
393 {"ds2786", DS2786},
394 {},
395 };
396 MODULE_DEVICE_TABLE(i2c, ds278x_id);
397
398 static struct i2c_driver ds278x_battery_driver = {
399 .driver = {
400 .name = "ds2782-battery",
401 },
402 .probe = ds278x_battery_probe,
403 .remove = ds278x_battery_remove,
404 .id_table = ds278x_id,
405 };
406
ds278x_init(void)407 static int __init ds278x_init(void)
408 {
409 return i2c_add_driver(&ds278x_battery_driver);
410 }
411 module_init(ds278x_init);
412
ds278x_exit(void)413 static void __exit ds278x_exit(void)
414 {
415 i2c_del_driver(&ds278x_battery_driver);
416 }
417 module_exit(ds278x_exit);
418
419 MODULE_AUTHOR("Ryan Mallon");
420 MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauage IC driver");
421 MODULE_LICENSE("GPL");
422