ds2782_battery.c revision 7cee9aefda78019b6e7c42fcf3600b9fd8aeb8d5 
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
48struct ds278x_info;
49
50struct 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) container_of(x, struct ds278x_info, battery)
57
58struct ds278x_info {
59	struct i2c_client	*client;
60	struct power_supply	battery;
61	struct ds278x_battery_ops  *ops;
62	struct delayed_work	bat_work;
63	int			id;
64	int                     rsns;
65	int			capacity;
66	int			status;		/* State Of Charge */
67};
68
69static DEFINE_IDR(battery_id);
70static DEFINE_MUTEX(battery_lock);
71
72static inline int ds278x_read_reg(struct ds278x_info *info, int reg, u8 *val)
73{
74	int ret;
75
76	ret = i2c_smbus_read_byte_data(info->client, reg);
77	if (ret < 0) {
78		dev_err(&info->client->dev, "register read failed\n");
79		return ret;
80	}
81
82	*val = ret;
83	return 0;
84}
85
86static inline int ds278x_read_reg16(struct ds278x_info *info, int reg_msb,
87				    s16 *val)
88{
89	int ret;
90
91	ret = i2c_smbus_read_word_data(info->client, reg_msb);
92	if (ret < 0) {
93		dev_err(&info->client->dev, "register read failed\n");
94		return ret;
95	}
96
97	*val = swab16(ret);
98	return 0;
99}
100
101static int ds278x_get_temp(struct ds278x_info *info, int *temp)
102{
103	s16 raw;
104	int err;
105
106	/*
107	 * Temperature is measured in units of 0.125 degrees celcius, the
108	 * power_supply class measures temperature in tenths of degrees
109	 * celsius. The temperature value is stored as a 10 bit number, plus
110	 * sign in the upper bits of a 16 bit register.
111	 */
112	err = ds278x_read_reg16(info, DS278x_REG_TEMP_MSB, &raw);
113	if (err)
114		return err;
115	*temp = ((raw / 32) * 125) / 100;
116	return 0;
117}
118
119static int ds2782_get_current(struct ds278x_info *info, int *current_uA)
120{
121	int sense_res;
122	int err;
123	u8 sense_res_raw;
124	s16 raw;
125
126	/*
127	 * The units of measurement for current are dependent on the value of
128	 * the sense resistor.
129	 */
130	err = ds278x_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw);
131	if (err)
132		return err;
133	if (sense_res_raw == 0) {
134		dev_err(&info->client->dev, "sense resistor value is 0\n");
135		return -ENXIO;
136	}
137	sense_res = 1000 / sense_res_raw;
138
139	dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n",
140		sense_res);
141	err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
142	if (err)
143		return err;
144	*current_uA = raw * (DS2782_CURRENT_UNITS / sense_res);
145	return 0;
146}
147
148static int ds2782_get_voltage(struct ds278x_info *info, int *voltage_uV)
149{
150	s16 raw;
151	int err;
152
153	/*
154	 * Voltage is measured in units of 4.88mV. The voltage is stored as
155	 * a 10-bit number plus sign, in the upper bits of a 16-bit register
156	 */
157	err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
158	if (err)
159		return err;
160	*voltage_uV = (raw / 32) * 4800;
161	return 0;
162}
163
164static int ds2782_get_capacity(struct ds278x_info *info, int *capacity)
165{
166	int err;
167	u8 raw;
168
169	err = ds278x_read_reg(info, DS2782_REG_RARC, &raw);
170	if (err)
171		return err;
172	*capacity = raw;
173	return 0;
174}
175
176static int ds2786_get_current(struct ds278x_info *info, int *current_uA)
177{
178	int err;
179	s16 raw;
180
181	err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
182	if (err)
183		return err;
184	*current_uA = (raw / 16) * (DS2786_CURRENT_UNITS / info->rsns);
185	return 0;
186}
187
188static int ds2786_get_voltage(struct ds278x_info *info, int *voltage_uV)
189{
190	s16 raw;
191	int err;
192
193	/*
194	 * Voltage is measured in units of 1.22mV. The voltage is stored as
195	 * a 10-bit number plus sign, in the upper bits of a 16-bit register
196	 */
197	err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
198	if (err)
199		return err;
200	*voltage_uV = (raw / 8) * 1220;
201	return 0;
202}
203
204static int ds2786_get_capacity(struct ds278x_info *info, int *capacity)
205{
206	int err;
207	u8 raw;
208
209	err = ds278x_read_reg(info, DS2786_REG_RARC, &raw);
210	if (err)
211		return err;
212	/* Relative capacity is displayed with resolution 0.5 % */
213	*capacity = raw/2 ;
214	return 0;
215}
216
217static int ds278x_get_status(struct ds278x_info *info, int *status)
218{
219	int err;
220	int current_uA;
221	int capacity;
222
223	err = info->ops->get_battery_current(info, &current_uA);
224	if (err)
225		return err;
226
227	err = info->ops->get_battery_capacity(info, &capacity);
228	if (err)
229		return err;
230
231	info->capacity = capacity;
232
233	if (capacity == 100)
234		*status = POWER_SUPPLY_STATUS_FULL;
235	else if (current_uA == 0)
236		*status = POWER_SUPPLY_STATUS_NOT_CHARGING;
237	else if (current_uA < 0)
238		*status = POWER_SUPPLY_STATUS_DISCHARGING;
239	else
240		*status = POWER_SUPPLY_STATUS_CHARGING;
241
242	return 0;
243}
244
245static int ds278x_battery_get_property(struct power_supply *psy,
246				       enum power_supply_property prop,
247				       union power_supply_propval *val)
248{
249	struct ds278x_info *info = to_ds278x_info(psy);
250	int ret;
251
252	switch (prop) {
253	case POWER_SUPPLY_PROP_STATUS:
254		ret = ds278x_get_status(info, &val->intval);
255		break;
256
257	case POWER_SUPPLY_PROP_CAPACITY:
258		ret = info->ops->get_battery_capacity(info, &val->intval);
259		break;
260
261	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
262		ret = info->ops->get_battery_voltage(info, &val->intval);
263		break;
264
265	case POWER_SUPPLY_PROP_CURRENT_NOW:
266		ret = info->ops->get_battery_current(info, &val->intval);
267		break;
268
269	case POWER_SUPPLY_PROP_TEMP:
270		ret = ds278x_get_temp(info, &val->intval);
271		break;
272
273	default:
274		ret = -EINVAL;
275	}
276
277	return ret;
278}
279
280static void ds278x_bat_update(struct ds278x_info *info)
281{
282	int old_status = info->status;
283	int old_capacity = info->capacity;
284
285	ds278x_get_status(info, &info->status);
286
287	if ((old_status != info->status) || (old_capacity != info->capacity))
288		power_supply_changed(&info->battery);
289}
290
291static void ds278x_bat_work(struct work_struct *work)
292{
293	struct ds278x_info *info;
294
295	info = container_of(work, struct ds278x_info, bat_work.work);
296	ds278x_bat_update(info);
297
298	schedule_delayed_work(&info->bat_work, DS278x_DELAY);
299}
300
301static enum power_supply_property ds278x_battery_props[] = {
302	POWER_SUPPLY_PROP_STATUS,
303	POWER_SUPPLY_PROP_CAPACITY,
304	POWER_SUPPLY_PROP_VOLTAGE_NOW,
305	POWER_SUPPLY_PROP_CURRENT_NOW,
306	POWER_SUPPLY_PROP_TEMP,
307};
308
309static void ds278x_power_supply_init(struct power_supply *battery)
310{
311	battery->type			= POWER_SUPPLY_TYPE_BATTERY;
312	battery->properties		= ds278x_battery_props;
313	battery->num_properties		= ARRAY_SIZE(ds278x_battery_props);
314	battery->get_property		= ds278x_battery_get_property;
315	battery->external_power_changed	= NULL;
316}
317
318static int ds278x_battery_remove(struct i2c_client *client)
319{
320	struct ds278x_info *info = i2c_get_clientdata(client);
321
322	power_supply_unregister(&info->battery);
323	kfree(info->battery.name);
324
325	mutex_lock(&battery_lock);
326	idr_remove(&battery_id, info->id);
327	mutex_unlock(&battery_lock);
328
329	cancel_delayed_work(&info->bat_work);
330
331	kfree(info);
332	return 0;
333}
334
335#ifdef CONFIG_PM
336
337static int ds278x_suspend(struct i2c_client *client,
338		pm_message_t state)
339{
340	struct ds278x_info *info = i2c_get_clientdata(client);
341
342	cancel_delayed_work(&info->bat_work);
343	return 0;
344}
345
346static int ds278x_resume(struct i2c_client *client)
347{
348	struct ds278x_info *info = i2c_get_clientdata(client);
349
350	schedule_delayed_work(&info->bat_work, DS278x_DELAY);
351	return 0;
352}
353
354#else
355
356#define ds278x_suspend NULL
357#define ds278x_resume NULL
358
359#endif /* CONFIG_PM */
360
361
362enum ds278x_num_id {
363	DS2782 = 0,
364	DS2786,
365};
366
367static struct ds278x_battery_ops ds278x_ops[] = {
368	[DS2782] = {
369		.get_battery_current  = ds2782_get_current,
370		.get_battery_voltage  = ds2782_get_voltage,
371		.get_battery_capacity = ds2782_get_capacity,
372	},
373	[DS2786] = {
374		.get_battery_current  = ds2786_get_current,
375		.get_battery_voltage  = ds2786_get_voltage,
376		.get_battery_capacity = ds2786_get_capacity,
377	}
378};
379
380static int ds278x_battery_probe(struct i2c_client *client,
381				const struct i2c_device_id *id)
382{
383	struct ds278x_platform_data *pdata = client->dev.platform_data;
384	struct ds278x_info *info;
385	int ret;
386	int num;
387
388	/*
389	 * ds2786 should have the sense resistor value set
390	 * in the platform data
391	 */
392	if (id->driver_data == DS2786 && !pdata) {
393		dev_err(&client->dev, "missing platform data for ds2786\n");
394		return -EINVAL;
395	}
396
397	/* Get an ID for this battery */
398	ret = idr_pre_get(&battery_id, GFP_KERNEL);
399	if (ret == 0) {
400		ret = -ENOMEM;
401		goto fail_id;
402	}
403
404	mutex_lock(&battery_lock);
405	ret = idr_get_new(&battery_id, client, &num);
406	mutex_unlock(&battery_lock);
407	if (ret < 0)
408		goto fail_id;
409
410	info = kzalloc(sizeof(*info), GFP_KERNEL);
411	if (!info) {
412		ret = -ENOMEM;
413		goto fail_info;
414	}
415
416	info->battery.name = kasprintf(GFP_KERNEL, "%s-%d", client->name, num);
417	if (!info->battery.name) {
418		ret = -ENOMEM;
419		goto fail_name;
420	}
421
422	if (id->driver_data == DS2786)
423		info->rsns = pdata->rsns;
424
425	i2c_set_clientdata(client, info);
426	info->client = client;
427	info->id = num;
428	info->ops  = &ds278x_ops[id->driver_data];
429	ds278x_power_supply_init(&info->battery);
430
431	info->capacity = 100;
432	info->status = POWER_SUPPLY_STATUS_FULL;
433
434	INIT_DELAYED_WORK(&info->bat_work, ds278x_bat_work);
435
436	ret = power_supply_register(&client->dev, &info->battery);
437	if (ret) {
438		dev_err(&client->dev, "failed to register battery\n");
439		goto fail_register;
440	} else {
441		schedule_delayed_work(&info->bat_work, DS278x_DELAY);
442	}
443
444	return 0;
445
446fail_register:
447	kfree(info->battery.name);
448fail_name:
449	kfree(info);
450fail_info:
451	mutex_lock(&battery_lock);
452	idr_remove(&battery_id, num);
453	mutex_unlock(&battery_lock);
454fail_id:
455	return ret;
456}
457
458static const struct i2c_device_id ds278x_id[] = {
459	{"ds2782", DS2782},
460	{"ds2786", DS2786},
461	{},
462};
463MODULE_DEVICE_TABLE(i2c, ds278x_id);
464
465static struct i2c_driver ds278x_battery_driver = {
466	.driver 	= {
467		.name	= "ds2782-battery",
468	},
469	.probe		= ds278x_battery_probe,
470	.remove		= ds278x_battery_remove,
471	.suspend	= ds278x_suspend,
472	.resume		= ds278x_resume,
473	.id_table	= ds278x_id,
474};
475module_i2c_driver(ds278x_battery_driver);
476
477MODULE_AUTHOR("Ryan Mallon");
478MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauage IC driver");
479MODULE_LICENSE("GPL");
480