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) power_supply_get_drvdata(x)
57
58struct ds278x_info {
59	struct i2c_client	*client;
60	struct power_supply	*battery;
61	struct power_supply_desc	battery_desc;
62	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
70static DEFINE_IDR(battery_id);
71static DEFINE_MUTEX(battery_lock);
72
73static 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
87static 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
102static 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
120static 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
149static 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
165static 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
177static 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
189static 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
205static 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
218static 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
246static 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
281static 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
292static 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
302static 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
310static 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
319static 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
338static 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
347static 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
357static SIMPLE_DEV_PM_OPS(ds278x_battery_pm_ops, ds278x_suspend, ds278x_resume);
358
359enum ds278x_num_id {
360	DS2782 = 0,
361	DS2786,
362};
363
364static 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
377static 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
443fail_register:
444	kfree(info->battery_desc.name);
445fail_name:
446	kfree(info);
447fail_info:
448	mutex_lock(&battery_lock);
449	idr_remove(&battery_id, num);
450	mutex_unlock(&battery_lock);
451fail_id:
452	return ret;
453}
454
455static const struct i2c_device_id ds278x_id[] = {
456	{"ds2782", DS2782},
457	{"ds2786", DS2786},
458	{},
459};
460MODULE_DEVICE_TABLE(i2c, ds278x_id);
461
462static 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};
471module_i2c_driver(ds278x_battery_driver);
472
473MODULE_AUTHOR("Ryan Mallon");
474MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauage IC driver");
475MODULE_LICENSE("GPL");
476