1/*
2 * I2C client/driver for the Linear Technology LTC2941 and LTC2943
3 * Battery Gas Gauge IC
4 *
5 * Copyright (C) 2014 Topic Embedded Systems
6 *
7 * Author: Auryn Verwegen
8 * Author: Mike Looijmans
9 */
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/types.h>
13#include <linux/errno.h>
14#include <linux/swab.h>
15#include <linux/i2c.h>
16#include <linux/delay.h>
17#include <linux/idr.h>
18#include <linux/power_supply.h>
19#include <linux/slab.h>
20
21#define I16_MSB(x)			((x >> 8) & 0xFF)
22#define I16_LSB(x)			(x & 0xFF)
23
24#define LTC294X_WORK_DELAY		10	/* Update delay in seconds */
25
26#define LTC294X_MAX_VALUE		0xFFFF
27#define LTC294X_MID_SUPPLY		0x7FFF
28
29#define LTC2941_MAX_PRESCALER_EXP	7
30#define LTC2943_MAX_PRESCALER_EXP	6
31
32enum ltc294x_reg {
33	LTC294X_REG_STATUS		= 0x00,
34	LTC294X_REG_CONTROL		= 0x01,
35	LTC294X_REG_ACC_CHARGE_MSB	= 0x02,
36	LTC294X_REG_ACC_CHARGE_LSB	= 0x03,
37	LTC294X_REG_THRESH_HIGH_MSB	= 0x04,
38	LTC294X_REG_THRESH_HIGH_LSB	= 0x05,
39	LTC294X_REG_THRESH_LOW_MSB	= 0x06,
40	LTC294X_REG_THRESH_LOW_LSB	= 0x07,
41	LTC294X_REG_VOLTAGE_MSB	= 0x08,
42	LTC294X_REG_VOLTAGE_LSB	= 0x09,
43	LTC294X_REG_CURRENT_MSB	= 0x0E,
44	LTC294X_REG_CURRENT_LSB	= 0x0F,
45	LTC294X_REG_TEMPERATURE_MSB	= 0x14,
46	LTC294X_REG_TEMPERATURE_LSB	= 0x15,
47};
48
49#define LTC2943_REG_CONTROL_MODE_MASK (BIT(7) | BIT(6))
50#define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
51#define LTC294X_REG_CONTROL_PRESCALER_MASK	(BIT(5) | BIT(4) | BIT(3))
52#define LTC294X_REG_CONTROL_SHUTDOWN_MASK	(BIT(0))
53#define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
54	((x << 3) & LTC294X_REG_CONTROL_PRESCALER_MASK)
55#define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED	0
56
57#define LTC2941_NUM_REGS	0x08
58#define LTC2943_NUM_REGS	0x18
59
60struct ltc294x_info {
61	struct i2c_client *client;	/* I2C Client pointer */
62	struct power_supply *supply;	/* Supply pointer */
63	struct power_supply_desc supply_desc;	/* Supply description */
64	struct delayed_work work;	/* Work scheduler */
65	int num_regs;	/* Number of registers (chip type) */
66	int id;		/* Identifier of ltc294x chip */
67	int charge;	/* Last charge register content */
68	int r_sense;	/* mOhm */
69	int Qlsb;	/* nAh */
70};
71
72static DEFINE_IDR(ltc294x_id);
73static DEFINE_MUTEX(ltc294x_lock);
74
75static inline int convert_bin_to_uAh(
76	const struct ltc294x_info *info, int Q)
77{
78	return ((Q * (info->Qlsb / 10))) / 100;
79}
80
81static inline int convert_uAh_to_bin(
82	const struct ltc294x_info *info, int uAh)
83{
84	int Q;
85
86	Q = (uAh * 100) / (info->Qlsb/10);
87	return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
88}
89
90static int ltc294x_read_regs(struct i2c_client *client,
91	enum ltc294x_reg reg, u8 *buf, int num_regs)
92{
93	int ret;
94	struct i2c_msg msgs[2] = { };
95	u8 reg_start = reg;
96
97	msgs[0].addr	= client->addr;
98	msgs[0].len	= 1;
99	msgs[0].buf	= &reg_start;
100
101	msgs[1].addr	= client->addr;
102	msgs[1].len	= num_regs;
103	msgs[1].buf	= buf;
104	msgs[1].flags	= I2C_M_RD;
105
106	ret = i2c_transfer(client->adapter, &msgs[0], 2);
107	if (ret < 0) {
108		dev_err(&client->dev, "ltc2941 read_reg failed!\n");
109		return ret;
110	}
111
112	dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
113		__func__, reg, num_regs, *buf);
114
115	return 0;
116}
117
118static int ltc294x_write_regs(struct i2c_client *client,
119	enum ltc294x_reg reg, const u8 *buf, int num_regs)
120{
121	int ret;
122	u8 reg_start = reg;
123
124	ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
125	if (ret < 0) {
126		dev_err(&client->dev, "ltc2941 write_reg failed!\n");
127		return ret;
128	}
129
130	dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
131		__func__, reg, num_regs, *buf);
132
133	return 0;
134}
135
136static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
137{
138	int ret;
139	u8 value;
140	u8 control;
141
142	/* Read status and control registers */
143	ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
144	if (ret < 0) {
145		dev_err(&info->client->dev,
146			"Could not read registers from device\n");
147		goto error_exit;
148	}
149
150	control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
151				LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
152	/* Put the 2943 into "monitor" mode, so it measures every 10 sec */
153	if (info->num_regs == LTC2943_NUM_REGS)
154		control |= LTC2943_REG_CONTROL_MODE_SCAN;
155
156	if (value != control) {
157		ret = ltc294x_write_regs(info->client,
158			LTC294X_REG_CONTROL, &control, 1);
159		if (ret < 0) {
160			dev_err(&info->client->dev,
161				"Could not write register\n");
162			goto error_exit;
163		}
164	}
165
166	return 0;
167
168error_exit:
169	return ret;
170}
171
172static int ltc294x_read_charge_register(const struct ltc294x_info *info)
173{
174	int ret;
175	u8 datar[2];
176
177	ret = ltc294x_read_regs(info->client,
178		LTC294X_REG_ACC_CHARGE_MSB, &datar[0], 2);
179	if (ret < 0)
180		return ret;
181	return (datar[0] << 8) + datar[1];
182}
183
184static int ltc294x_get_charge_now(const struct ltc294x_info *info, int *val)
185{
186	int value = ltc294x_read_charge_register(info);
187
188	if (value < 0)
189		return value;
190	/* When r_sense < 0, this counts up when the battery discharges */
191	if (info->Qlsb < 0)
192		value -= 0xFFFF;
193	*val = convert_bin_to_uAh(info, value);
194	return 0;
195}
196
197static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
198{
199	int ret;
200	u8 dataw[2];
201	u8 ctrl_reg;
202	s32 value;
203
204	value = convert_uAh_to_bin(info, val);
205	/* Direction depends on how sense+/- were connected */
206	if (info->Qlsb < 0)
207		value += 0xFFFF;
208	if ((value < 0) || (value > 0xFFFF)) /* input validation */
209		return -EINVAL;
210
211	/* Read control register */
212	ret = ltc294x_read_regs(info->client,
213		LTC294X_REG_CONTROL, &ctrl_reg, 1);
214	if (ret < 0)
215		return ret;
216	/* Disable analog section */
217	ctrl_reg |= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
218	ret = ltc294x_write_regs(info->client,
219		LTC294X_REG_CONTROL, &ctrl_reg, 1);
220	if (ret < 0)
221		return ret;
222	/* Set new charge value */
223	dataw[0] = I16_MSB(value);
224	dataw[1] = I16_LSB(value);
225	ret = ltc294x_write_regs(info->client,
226		LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
227	if (ret < 0)
228		goto error_exit;
229	/* Enable analog section */
230error_exit:
231	ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
232	ret = ltc294x_write_regs(info->client,
233		LTC294X_REG_CONTROL, &ctrl_reg, 1);
234
235	return ret < 0 ? ret : 0;
236}
237
238static int ltc294x_get_charge_counter(
239	const struct ltc294x_info *info, int *val)
240{
241	int value = ltc294x_read_charge_register(info);
242
243	if (value < 0)
244		return value;
245	value -= LTC294X_MID_SUPPLY;
246	*val = convert_bin_to_uAh(info, value);
247	return 0;
248}
249
250static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
251{
252	int ret;
253	u8 datar[2];
254	u32 value;
255
256	ret = ltc294x_read_regs(info->client,
257		LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
258	value = (datar[0] << 8) | datar[1];
259	*val = ((value * 23600) / 0xFFFF) * 1000; /* in uV */
260	return ret;
261}
262
263static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
264{
265	int ret;
266	u8 datar[2];
267	s32 value;
268
269	ret = ltc294x_read_regs(info->client,
270		LTC294X_REG_CURRENT_MSB, &datar[0], 2);
271	value = (datar[0] << 8) | datar[1];
272	value -= 0x7FFF;
273	/* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
274	 * the formula below keeps everything in s32 range while preserving
275	 * enough digits */
276	*val = 1000 * ((60000 * value) / (info->r_sense * 0x7FFF)); /* in uA */
277	return ret;
278}
279
280static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
281{
282	int ret;
283	u8 datar[2];
284	u32 value;
285
286	ret = ltc294x_read_regs(info->client,
287		LTC294X_REG_TEMPERATURE_MSB, &datar[0], 2);
288	value = (datar[0] << 8) | datar[1];
289	/* Full-scale is 510 Kelvin, convert to centidegrees  */
290	*val = (((51000 * value) / 0xFFFF) - 27215);
291	return ret;
292}
293
294static int ltc294x_get_property(struct power_supply *psy,
295				enum power_supply_property prop,
296				union power_supply_propval *val)
297{
298	struct ltc294x_info *info = power_supply_get_drvdata(psy);
299
300	switch (prop) {
301	case POWER_SUPPLY_PROP_CHARGE_NOW:
302		return ltc294x_get_charge_now(info, &val->intval);
303	case POWER_SUPPLY_PROP_CHARGE_COUNTER:
304		return ltc294x_get_charge_counter(info, &val->intval);
305	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
306		return ltc294x_get_voltage(info, &val->intval);
307	case POWER_SUPPLY_PROP_CURRENT_NOW:
308		return ltc294x_get_current(info, &val->intval);
309	case POWER_SUPPLY_PROP_TEMP:
310		return ltc294x_get_temperature(info, &val->intval);
311	default:
312		return -EINVAL;
313	}
314}
315
316static int ltc294x_set_property(struct power_supply *psy,
317	enum power_supply_property psp,
318	const union power_supply_propval *val)
319{
320	struct ltc294x_info *info = power_supply_get_drvdata(psy);
321
322	switch (psp) {
323	case POWER_SUPPLY_PROP_CHARGE_NOW:
324		return ltc294x_set_charge_now(info, val->intval);
325	default:
326		return -EPERM;
327	}
328}
329
330static int ltc294x_property_is_writeable(
331	struct power_supply *psy, enum power_supply_property psp)
332{
333	switch (psp) {
334	case POWER_SUPPLY_PROP_CHARGE_NOW:
335		return 1;
336	default:
337		return 0;
338	}
339}
340
341static void ltc294x_update(struct ltc294x_info *info)
342{
343	int charge = ltc294x_read_charge_register(info);
344
345	if (charge != info->charge) {
346		info->charge = charge;
347		power_supply_changed(info->supply);
348	}
349}
350
351static void ltc294x_work(struct work_struct *work)
352{
353	struct ltc294x_info *info;
354
355	info = container_of(work, struct ltc294x_info, work.work);
356	ltc294x_update(info);
357	schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
358}
359
360static enum power_supply_property ltc294x_properties[] = {
361	POWER_SUPPLY_PROP_CHARGE_COUNTER,
362	POWER_SUPPLY_PROP_CHARGE_NOW,
363	POWER_SUPPLY_PROP_VOLTAGE_NOW,
364	POWER_SUPPLY_PROP_CURRENT_NOW,
365	POWER_SUPPLY_PROP_TEMP,
366};
367
368static int ltc294x_i2c_remove(struct i2c_client *client)
369{
370	struct ltc294x_info *info = i2c_get_clientdata(client);
371
372	cancel_delayed_work(&info->work);
373	power_supply_unregister(info->supply);
374	kfree(info->supply_desc.name);
375	mutex_lock(&ltc294x_lock);
376	idr_remove(&ltc294x_id, info->id);
377	mutex_unlock(&ltc294x_lock);
378	return 0;
379}
380
381static int ltc294x_i2c_probe(struct i2c_client *client,
382	const struct i2c_device_id *id)
383{
384	struct power_supply_config psy_cfg = {};
385	struct ltc294x_info *info;
386	int ret;
387	int num;
388	u32 prescaler_exp;
389	s32 r_sense;
390	struct device_node *np;
391
392	mutex_lock(&ltc294x_lock);
393	ret = idr_alloc(&ltc294x_id, client, 0, 0, GFP_KERNEL);
394	mutex_unlock(&ltc294x_lock);
395	if (ret < 0)
396		goto fail_id;
397
398	num = ret;
399
400	info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
401	if (info == NULL) {
402		ret = -ENOMEM;
403		goto fail_info;
404	}
405
406	i2c_set_clientdata(client, info);
407
408	info->num_regs = id->driver_data;
409	info->supply_desc.name = kasprintf(GFP_KERNEL, "%s-%d", client->name,
410					   num);
411	if (!info->supply_desc.name) {
412		ret = -ENOMEM;
413		goto fail_name;
414	}
415
416	np = of_node_get(client->dev.of_node);
417
418	/* r_sense can be negative, when sense+ is connected to the battery
419	 * instead of the sense-. This results in reversed measurements. */
420	ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
421	if (ret < 0) {
422		dev_err(&client->dev,
423			"Could not find lltc,resistor-sense in devicetree\n");
424		goto fail_name;
425	}
426	info->r_sense = r_sense;
427
428	ret = of_property_read_u32(np, "lltc,prescaler-exponent",
429		&prescaler_exp);
430	if (ret < 0) {
431		dev_warn(&client->dev,
432			"lltc,prescaler-exponent not in devicetree\n");
433		prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
434	}
435
436	if (info->num_regs == LTC2943_NUM_REGS) {
437		if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
438			prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
439		info->Qlsb = ((340 * 50000) / r_sense) /
440				(4096 / (1 << (2*prescaler_exp)));
441	} else {
442		if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
443			prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
444		info->Qlsb = ((85 * 50000) / r_sense) /
445				(128 / (1 << prescaler_exp));
446	}
447
448	info->client = client;
449	info->id = num;
450	info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
451	info->supply_desc.properties = ltc294x_properties;
452	if (info->num_regs >= LTC294X_REG_TEMPERATURE_LSB)
453		info->supply_desc.num_properties =
454			ARRAY_SIZE(ltc294x_properties);
455	else if (info->num_regs >= LTC294X_REG_CURRENT_LSB)
456		info->supply_desc.num_properties =
457			ARRAY_SIZE(ltc294x_properties) - 1;
458	else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
459		info->supply_desc.num_properties =
460			ARRAY_SIZE(ltc294x_properties) - 2;
461	else
462		info->supply_desc.num_properties =
463			ARRAY_SIZE(ltc294x_properties) - 3;
464	info->supply_desc.get_property = ltc294x_get_property;
465	info->supply_desc.set_property = ltc294x_set_property;
466	info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
467	info->supply_desc.external_power_changed	= NULL;
468
469	psy_cfg.drv_data = info;
470
471	INIT_DELAYED_WORK(&info->work, ltc294x_work);
472
473	ret = ltc294x_reset(info, prescaler_exp);
474	if (ret < 0) {
475		dev_err(&client->dev, "Communication with chip failed\n");
476		goto fail_comm;
477	}
478
479	info->supply = power_supply_register(&client->dev, &info->supply_desc,
480					     &psy_cfg);
481	if (IS_ERR(info->supply)) {
482		dev_err(&client->dev, "failed to register ltc2941\n");
483		ret = PTR_ERR(info->supply);
484		goto fail_register;
485	} else {
486		schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
487	}
488
489	return 0;
490
491fail_register:
492	kfree(info->supply_desc.name);
493fail_comm:
494fail_name:
495fail_info:
496	mutex_lock(&ltc294x_lock);
497	idr_remove(&ltc294x_id, num);
498	mutex_unlock(&ltc294x_lock);
499fail_id:
500	return ret;
501}
502
503#ifdef CONFIG_PM_SLEEP
504
505static int ltc294x_suspend(struct device *dev)
506{
507	struct i2c_client *client = to_i2c_client(dev);
508	struct ltc294x_info *info = i2c_get_clientdata(client);
509
510	cancel_delayed_work(&info->work);
511	return 0;
512}
513
514static int ltc294x_resume(struct device *dev)
515{
516	struct i2c_client *client = to_i2c_client(dev);
517	struct ltc294x_info *info = i2c_get_clientdata(client);
518
519	schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
520	return 0;
521}
522
523static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
524#define LTC294X_PM_OPS (&ltc294x_pm_ops)
525
526#else
527#define LTC294X_PM_OPS NULL
528#endif /* CONFIG_PM_SLEEP */
529
530
531static const struct i2c_device_id ltc294x_i2c_id[] = {
532	{"ltc2941", LTC2941_NUM_REGS},
533	{"ltc2943", LTC2943_NUM_REGS},
534	{ },
535};
536MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);
537
538static struct i2c_driver ltc294x_driver = {
539	.driver = {
540		.name	= "LTC2941",
541		.pm	= LTC294X_PM_OPS,
542	},
543	.probe		= ltc294x_i2c_probe,
544	.remove		= ltc294x_i2c_remove,
545	.id_table	= ltc294x_i2c_id,
546};
547module_i2c_driver(ltc294x_driver);
548
549MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
550MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
551MODULE_DESCRIPTION("LTC2941/LTC2943 Battery Gas Gauge IC driver");
552MODULE_LICENSE("GPL");
553