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  * UEvent sending added by Evgeny Romanov <romanov@neurosoft.ru>
11  *
12  * This program is free software; you can redistribute it and/or modify
13  * it under the terms of the GNU General Public License version 2 as
14  * published by the Free Software Foundation.
15  *
16  */
17 
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/types.h>
21 #include <linux/errno.h>
22 #include <linux/swab.h>
23 #include <linux/i2c.h>
24 #include <linux/delay.h>
25 #include <linux/idr.h>
26 #include <linux/power_supply.h>
27 #include <linux/slab.h>
28 #include <linux/ds2782_battery.h>
29 
30 #define DS2782_REG_RARC		0x06	/* Remaining active relative capacity */
31 
32 #define DS278x_REG_VOLT_MSB	0x0c
33 #define DS278x_REG_TEMP_MSB	0x0a
34 #define DS278x_REG_CURRENT_MSB	0x0e
35 
36 /* EEPROM Block */
37 #define DS2782_REG_RSNSP	0x69	/* Sense resistor value */
38 
39 /* Current unit measurement in uA for a 1 milli-ohm sense resistor */
40 #define DS2782_CURRENT_UNITS	1563
41 
42 #define DS2786_REG_RARC		0x02	/* Remaining active relative capacity */
43 
44 #define DS2786_CURRENT_UNITS	25
45 
46 #define DS278x_DELAY		1000
47 
48 struct ds278x_info;
49 
50 struct ds278x_battery_ops {
51 	int (*get_battery_current)(struct ds278x_info *info, int *current_uA);
52 	int (*get_battery_voltage)(struct ds278x_info *info, int *voltage_uV);
53 	int (*get_battery_capacity)(struct ds278x_info *info, int *capacity);
54 };
55 
56 #define to_ds278x_info(x) power_supply_get_drvdata(x)
57 
58 struct ds278x_info {
59 	struct i2c_client	*client;
60 	struct power_supply	*battery;
61 	struct power_supply_desc	battery_desc;
62 	const struct ds278x_battery_ops *ops;
63 	struct delayed_work	bat_work;
64 	int			id;
65 	int                     rsns;
66 	int			capacity;
67 	int			status;		/* State Of Charge */
68 };
69 
70 static DEFINE_IDR(battery_id);
71 static DEFINE_MUTEX(battery_lock);
72 
73 static inline int ds278x_read_reg(struct ds278x_info *info, int reg, u8 *val)
74 {
75 	int ret;
76 
77 	ret = i2c_smbus_read_byte_data(info->client, reg);
78 	if (ret < 0) {
79 		dev_err(&info->client->dev, "register read failed\n");
80 		return ret;
81 	}
82 
83 	*val = ret;
84 	return 0;
85 }
86 
87 static inline int ds278x_read_reg16(struct ds278x_info *info, int reg_msb,
88 				    s16 *val)
89 {
90 	int ret;
91 
92 	ret = i2c_smbus_read_word_data(info->client, reg_msb);
93 	if (ret < 0) {
94 		dev_err(&info->client->dev, "register read failed\n");
95 		return ret;
96 	}
97 
98 	*val = swab16(ret);
99 	return 0;
100 }
101 
102 static int ds278x_get_temp(struct ds278x_info *info, int *temp)
103 {
104 	s16 raw;
105 	int err;
106 
107 	/*
108 	 * Temperature is measured in units of 0.125 degrees celcius, the
109 	 * power_supply class measures temperature in tenths of degrees
110 	 * celsius. The temperature value is stored as a 10 bit number, plus
111 	 * sign in the upper bits of a 16 bit register.
112 	 */
113 	err = ds278x_read_reg16(info, DS278x_REG_TEMP_MSB, &raw);
114 	if (err)
115 		return err;
116 	*temp = ((raw / 32) * 125) / 100;
117 	return 0;
118 }
119 
120 static int ds2782_get_current(struct ds278x_info *info, int *current_uA)
121 {
122 	int sense_res;
123 	int err;
124 	u8 sense_res_raw;
125 	s16 raw;
126 
127 	/*
128 	 * The units of measurement for current are dependent on the value of
129 	 * the sense resistor.
130 	 */
131 	err = ds278x_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw);
132 	if (err)
133 		return err;
134 	if (sense_res_raw == 0) {
135 		dev_err(&info->client->dev, "sense resistor value is 0\n");
136 		return -ENXIO;
137 	}
138 	sense_res = 1000 / sense_res_raw;
139 
140 	dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n",
141 		sense_res);
142 	err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
143 	if (err)
144 		return err;
145 	*current_uA = raw * (DS2782_CURRENT_UNITS / sense_res);
146 	return 0;
147 }
148 
149 static int ds2782_get_voltage(struct ds278x_info *info, int *voltage_uV)
150 {
151 	s16 raw;
152 	int err;
153 
154 	/*
155 	 * Voltage is measured in units of 4.88mV. The voltage is stored as
156 	 * a 10-bit number plus sign, in the upper bits of a 16-bit register
157 	 */
158 	err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
159 	if (err)
160 		return err;
161 	*voltage_uV = (raw / 32) * 4800;
162 	return 0;
163 }
164 
165 static int ds2782_get_capacity(struct ds278x_info *info, int *capacity)
166 {
167 	int err;
168 	u8 raw;
169 
170 	err = ds278x_read_reg(info, DS2782_REG_RARC, &raw);
171 	if (err)
172 		return err;
173 	*capacity = raw;
174 	return 0;
175 }
176 
177 static int ds2786_get_current(struct ds278x_info *info, int *current_uA)
178 {
179 	int err;
180 	s16 raw;
181 
182 	err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
183 	if (err)
184 		return err;
185 	*current_uA = (raw / 16) * (DS2786_CURRENT_UNITS / info->rsns);
186 	return 0;
187 }
188 
189 static int ds2786_get_voltage(struct ds278x_info *info, int *voltage_uV)
190 {
191 	s16 raw;
192 	int err;
193 
194 	/*
195 	 * Voltage is measured in units of 1.22mV. The voltage is stored as
196 	 * a 12-bit number plus sign, in the upper bits of a 16-bit register
197 	 */
198 	err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
199 	if (err)
200 		return err;
201 	*voltage_uV = (raw / 8) * 1220;
202 	return 0;
203 }
204 
205 static int ds2786_get_capacity(struct ds278x_info *info, int *capacity)
206 {
207 	int err;
208 	u8 raw;
209 
210 	err = ds278x_read_reg(info, DS2786_REG_RARC, &raw);
211 	if (err)
212 		return err;
213 	/* Relative capacity is displayed with resolution 0.5 % */
214 	*capacity = raw/2 ;
215 	return 0;
216 }
217 
218 static int ds278x_get_status(struct ds278x_info *info, int *status)
219 {
220 	int err;
221 	int current_uA;
222 	int capacity;
223 
224 	err = info->ops->get_battery_current(info, &current_uA);
225 	if (err)
226 		return err;
227 
228 	err = info->ops->get_battery_capacity(info, &capacity);
229 	if (err)
230 		return err;
231 
232 	info->capacity = capacity;
233 
234 	if (capacity == 100)
235 		*status = POWER_SUPPLY_STATUS_FULL;
236 	else if (current_uA == 0)
237 		*status = POWER_SUPPLY_STATUS_NOT_CHARGING;
238 	else if (current_uA < 0)
239 		*status = POWER_SUPPLY_STATUS_DISCHARGING;
240 	else
241 		*status = POWER_SUPPLY_STATUS_CHARGING;
242 
243 	return 0;
244 }
245 
246 static int ds278x_battery_get_property(struct power_supply *psy,
247 				       enum power_supply_property prop,
248 				       union power_supply_propval *val)
249 {
250 	struct ds278x_info *info = to_ds278x_info(psy);
251 	int ret;
252 
253 	switch (prop) {
254 	case POWER_SUPPLY_PROP_STATUS:
255 		ret = ds278x_get_status(info, &val->intval);
256 		break;
257 
258 	case POWER_SUPPLY_PROP_CAPACITY:
259 		ret = info->ops->get_battery_capacity(info, &val->intval);
260 		break;
261 
262 	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
263 		ret = info->ops->get_battery_voltage(info, &val->intval);
264 		break;
265 
266 	case POWER_SUPPLY_PROP_CURRENT_NOW:
267 		ret = info->ops->get_battery_current(info, &val->intval);
268 		break;
269 
270 	case POWER_SUPPLY_PROP_TEMP:
271 		ret = ds278x_get_temp(info, &val->intval);
272 		break;
273 
274 	default:
275 		ret = -EINVAL;
276 	}
277 
278 	return ret;
279 }
280 
281 static void ds278x_bat_update(struct ds278x_info *info)
282 {
283 	int old_status = info->status;
284 	int old_capacity = info->capacity;
285 
286 	ds278x_get_status(info, &info->status);
287 
288 	if ((old_status != info->status) || (old_capacity != info->capacity))
289 		power_supply_changed(info->battery);
290 }
291 
292 static void ds278x_bat_work(struct work_struct *work)
293 {
294 	struct ds278x_info *info;
295 
296 	info = container_of(work, struct ds278x_info, bat_work.work);
297 	ds278x_bat_update(info);
298 
299 	schedule_delayed_work(&info->bat_work, DS278x_DELAY);
300 }
301 
302 static enum power_supply_property ds278x_battery_props[] = {
303 	POWER_SUPPLY_PROP_STATUS,
304 	POWER_SUPPLY_PROP_CAPACITY,
305 	POWER_SUPPLY_PROP_VOLTAGE_NOW,
306 	POWER_SUPPLY_PROP_CURRENT_NOW,
307 	POWER_SUPPLY_PROP_TEMP,
308 };
309 
310 static void ds278x_power_supply_init(struct power_supply_desc *battery)
311 {
312 	battery->type			= POWER_SUPPLY_TYPE_BATTERY;
313 	battery->properties		= ds278x_battery_props;
314 	battery->num_properties		= ARRAY_SIZE(ds278x_battery_props);
315 	battery->get_property		= ds278x_battery_get_property;
316 	battery->external_power_changed	= NULL;
317 }
318 
319 static int ds278x_battery_remove(struct i2c_client *client)
320 {
321 	struct ds278x_info *info = i2c_get_clientdata(client);
322 
323 	power_supply_unregister(info->battery);
324 	kfree(info->battery_desc.name);
325 
326 	mutex_lock(&battery_lock);
327 	idr_remove(&battery_id, info->id);
328 	mutex_unlock(&battery_lock);
329 
330 	cancel_delayed_work(&info->bat_work);
331 
332 	kfree(info);
333 	return 0;
334 }
335 
336 #ifdef CONFIG_PM_SLEEP
337 
338 static int ds278x_suspend(struct device *dev)
339 {
340 	struct i2c_client *client = to_i2c_client(dev);
341 	struct ds278x_info *info = i2c_get_clientdata(client);
342 
343 	cancel_delayed_work(&info->bat_work);
344 	return 0;
345 }
346 
347 static int ds278x_resume(struct device *dev)
348 {
349 	struct i2c_client *client = to_i2c_client(dev);
350 	struct ds278x_info *info = i2c_get_clientdata(client);
351 
352 	schedule_delayed_work(&info->bat_work, DS278x_DELAY);
353 	return 0;
354 }
355 #endif /* CONFIG_PM_SLEEP */
356 
357 static SIMPLE_DEV_PM_OPS(ds278x_battery_pm_ops, ds278x_suspend, ds278x_resume);
358 
359 enum ds278x_num_id {
360 	DS2782 = 0,
361 	DS2786,
362 };
363 
364 static const struct ds278x_battery_ops ds278x_ops[] = {
365 	[DS2782] = {
366 		.get_battery_current  = ds2782_get_current,
367 		.get_battery_voltage  = ds2782_get_voltage,
368 		.get_battery_capacity = ds2782_get_capacity,
369 	},
370 	[DS2786] = {
371 		.get_battery_current  = ds2786_get_current,
372 		.get_battery_voltage  = ds2786_get_voltage,
373 		.get_battery_capacity = ds2786_get_capacity,
374 	}
375 };
376 
377 static int ds278x_battery_probe(struct i2c_client *client,
378 				const struct i2c_device_id *id)
379 {
380 	struct ds278x_platform_data *pdata = client->dev.platform_data;
381 	struct power_supply_config psy_cfg = {};
382 	struct ds278x_info *info;
383 	int ret;
384 	int num;
385 
386 	/*
387 	 * ds2786 should have the sense resistor value set
388 	 * in the platform data
389 	 */
390 	if (id->driver_data == DS2786 && !pdata) {
391 		dev_err(&client->dev, "missing platform data for ds2786\n");
392 		return -EINVAL;
393 	}
394 
395 	/* Get an ID for this battery */
396 	mutex_lock(&battery_lock);
397 	ret = idr_alloc(&battery_id, client, 0, 0, GFP_KERNEL);
398 	mutex_unlock(&battery_lock);
399 	if (ret < 0)
400 		goto fail_id;
401 	num = ret;
402 
403 	info = kzalloc(sizeof(*info), GFP_KERNEL);
404 	if (!info) {
405 		ret = -ENOMEM;
406 		goto fail_info;
407 	}
408 
409 	info->battery_desc.name = kasprintf(GFP_KERNEL, "%s-%d",
410 					    client->name, num);
411 	if (!info->battery_desc.name) {
412 		ret = -ENOMEM;
413 		goto fail_name;
414 	}
415 
416 	if (id->driver_data == DS2786)
417 		info->rsns = pdata->rsns;
418 
419 	i2c_set_clientdata(client, info);
420 	info->client = client;
421 	info->id = num;
422 	info->ops  = &ds278x_ops[id->driver_data];
423 	ds278x_power_supply_init(&info->battery_desc);
424 	psy_cfg.drv_data = info;
425 
426 	info->capacity = 100;
427 	info->status = POWER_SUPPLY_STATUS_FULL;
428 
429 	INIT_DELAYED_WORK(&info->bat_work, ds278x_bat_work);
430 
431 	info->battery = power_supply_register(&client->dev,
432 					      &info->battery_desc, &psy_cfg);
433 	if (IS_ERR(info->battery)) {
434 		dev_err(&client->dev, "failed to register battery\n");
435 		ret = PTR_ERR(info->battery);
436 		goto fail_register;
437 	} else {
438 		schedule_delayed_work(&info->bat_work, DS278x_DELAY);
439 	}
440 
441 	return 0;
442 
443 fail_register:
444 	kfree(info->battery_desc.name);
445 fail_name:
446 	kfree(info);
447 fail_info:
448 	mutex_lock(&battery_lock);
449 	idr_remove(&battery_id, num);
450 	mutex_unlock(&battery_lock);
451 fail_id:
452 	return ret;
453 }
454 
455 static const struct i2c_device_id ds278x_id[] = {
456 	{"ds2782", DS2782},
457 	{"ds2786", DS2786},
458 	{},
459 };
460 MODULE_DEVICE_TABLE(i2c, ds278x_id);
461 
462 static struct i2c_driver ds278x_battery_driver = {
463 	.driver 	= {
464 		.name	= "ds2782-battery",
465 		.pm	= &ds278x_battery_pm_ops,
466 	},
467 	.probe		= ds278x_battery_probe,
468 	.remove		= ds278x_battery_remove,
469 	.id_table	= ds278x_id,
470 };
471 module_i2c_driver(ds278x_battery_driver);
472 
473 MODULE_AUTHOR("Ryan Mallon");
474 MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauge IC driver");
475 MODULE_LICENSE("GPL");
476