summaryrefslogtreecommitdiff
path: root/drivers/power/ltc2941-battery-gauge.c
blob: 4adf2ba021ceb2a2f99510d4ed28bfbae51617c4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
/*
 * I2C client/driver for the Linear Technology LTC2941 and LTC2943
 * Battery Gas Gauge IC
 *
 * Copyright (C) 2014 Topic Embedded Systems
 *
 * Author: Auryn Verwegen
 * Author: Mike Looijmans
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/swab.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/power_supply.h>
#include <linux/slab.h>

#define I16_MSB(x)			((x >> 8) & 0xFF)
#define I16_LSB(x)			(x & 0xFF)

#define LTC294X_WORK_DELAY		10	/* Update delay in seconds */

#define LTC294X_MAX_VALUE		0xFFFF
#define LTC294X_MID_SUPPLY		0x7FFF

#define LTC2941_MAX_PRESCALER_EXP	7
#define LTC2943_MAX_PRESCALER_EXP	6

enum ltc294x_reg {
	LTC294X_REG_STATUS		= 0x00,
	LTC294X_REG_CONTROL		= 0x01,
	LTC294X_REG_ACC_CHARGE_MSB	= 0x02,
	LTC294X_REG_ACC_CHARGE_LSB	= 0x03,
	LTC294X_REG_THRESH_HIGH_MSB	= 0x04,
	LTC294X_REG_THRESH_HIGH_LSB	= 0x05,
	LTC294X_REG_THRESH_LOW_MSB	= 0x06,
	LTC294X_REG_THRESH_LOW_LSB	= 0x07,
	LTC294X_REG_VOLTAGE_MSB	= 0x08,
	LTC294X_REG_VOLTAGE_LSB	= 0x09,
	LTC294X_REG_CURRENT_MSB	= 0x0E,
	LTC294X_REG_CURRENT_LSB	= 0x0F,
	LTC294X_REG_TEMPERATURE_MSB	= 0x14,
	LTC294X_REG_TEMPERATURE_LSB	= 0x15,
};

#define LTC2943_REG_CONTROL_MODE_MASK (BIT(7) | BIT(6))
#define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
#define LTC294X_REG_CONTROL_PRESCALER_MASK	(BIT(5) | BIT(4) | BIT(3))
#define LTC294X_REG_CONTROL_SHUTDOWN_MASK	(BIT(0))
#define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
	((x << 3) & LTC294X_REG_CONTROL_PRESCALER_MASK)
#define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED	0

#define LTC2941_NUM_REGS	0x08
#define LTC2943_NUM_REGS	0x18

struct ltc294x_info {
	struct i2c_client *client;	/* I2C Client pointer */
	struct power_supply *supply;	/* Supply pointer */
	struct power_supply_desc supply_desc;	/* Supply description */
	struct delayed_work work;	/* Work scheduler */
	int num_regs;	/* Number of registers (chip type) */
	int charge;	/* Last charge register content */
	int r_sense;	/* mOhm */
	int Qlsb;	/* nAh */
};

static inline int convert_bin_to_uAh(
	const struct ltc294x_info *info, int Q)
{
	return ((Q * (info->Qlsb / 10))) / 100;
}

static inline int convert_uAh_to_bin(
	const struct ltc294x_info *info, int uAh)
{
	int Q;

	Q = (uAh * 100) / (info->Qlsb/10);
	return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
}

static int ltc294x_read_regs(struct i2c_client *client,
	enum ltc294x_reg reg, u8 *buf, int num_regs)
{
	int ret;
	struct i2c_msg msgs[2] = { };
	u8 reg_start = reg;

	msgs[0].addr	= client->addr;
	msgs[0].len	= 1;
	msgs[0].buf	= &reg_start;

	msgs[1].addr	= client->addr;
	msgs[1].len	= num_regs;
	msgs[1].buf	= buf;
	msgs[1].flags	= I2C_M_RD;

	ret = i2c_transfer(client->adapter, &msgs[0], 2);
	if (ret < 0) {
		dev_err(&client->dev, "ltc2941 read_reg failed!\n");
		return ret;
	}

	dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
		__func__, reg, num_regs, *buf);

	return 0;
}

static int ltc294x_write_regs(struct i2c_client *client,
	enum ltc294x_reg reg, const u8 *buf, int num_regs)
{
	int ret;
	u8 reg_start = reg;

	ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
	if (ret < 0) {
		dev_err(&client->dev, "ltc2941 write_reg failed!\n");
		return ret;
	}

	dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
		__func__, reg, num_regs, *buf);

	return 0;
}

static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
{
	int ret;
	u8 value;
	u8 control;

	/* Read status and control registers */
	ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
	if (ret < 0) {
		dev_err(&info->client->dev,
			"Could not read registers from device\n");
		goto error_exit;
	}

	control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
				LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
	/* Put the 2943 into "monitor" mode, so it measures every 10 sec */
	if (info->num_regs == LTC2943_NUM_REGS)
		control |= LTC2943_REG_CONTROL_MODE_SCAN;

	if (value != control) {
		ret = ltc294x_write_regs(info->client,
			LTC294X_REG_CONTROL, &control, 1);
		if (ret < 0) {
			dev_err(&info->client->dev,
				"Could not write register\n");
			goto error_exit;
		}
	}

	return 0;

error_exit:
	return ret;
}

static int ltc294x_read_charge_register(const struct ltc294x_info *info)
{
	int ret;
	u8 datar[2];

	ret = ltc294x_read_regs(info->client,
		LTC294X_REG_ACC_CHARGE_MSB, &datar[0], 2);
	if (ret < 0)
		return ret;
	return (datar[0] << 8) + datar[1];
}

static int ltc294x_get_charge_now(const struct ltc294x_info *info, int *val)
{
	int value = ltc294x_read_charge_register(info);

	if (value < 0)
		return value;
	/* When r_sense < 0, this counts up when the battery discharges */
	if (info->Qlsb < 0)
		value -= 0xFFFF;
	*val = convert_bin_to_uAh(info, value);
	return 0;
}

static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
{
	int ret;
	u8 dataw[2];
	u8 ctrl_reg;
	s32 value;

	value = convert_uAh_to_bin(info, val);
	/* Direction depends on how sense+/- were connected */
	if (info->Qlsb < 0)
		value += 0xFFFF;
	if ((value < 0) || (value > 0xFFFF)) /* input validation */
		return -EINVAL;

	/* Read control register */
	ret = ltc294x_read_regs(info->client,
		LTC294X_REG_CONTROL, &ctrl_reg, 1);
	if (ret < 0)
		return ret;
	/* Disable analog section */
	ctrl_reg |= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
	ret = ltc294x_write_regs(info->client,
		LTC294X_REG_CONTROL, &ctrl_reg, 1);
	if (ret < 0)
		return ret;
	/* Set new charge value */
	dataw[0] = I16_MSB(value);
	dataw[1] = I16_LSB(value);
	ret = ltc294x_write_regs(info->client,
		LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
	if (ret < 0)
		goto error_exit;
	/* Enable analog section */
error_exit:
	ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
	ret = ltc294x_write_regs(info->client,
		LTC294X_REG_CONTROL, &ctrl_reg, 1);

	return ret < 0 ? ret : 0;
}

static int ltc294x_get_charge_counter(
	const struct ltc294x_info *info, int *val)
{
	int value = ltc294x_read_charge_register(info);

	if (value < 0)
		return value;
	value -= LTC294X_MID_SUPPLY;
	*val = convert_bin_to_uAh(info, value);
	return 0;
}

static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
{
	int ret;
	u8 datar[2];
	u32 value;

	ret = ltc294x_read_regs(info->client,
		LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
	value = (datar[0] << 8) | datar[1];
	*val = ((value * 23600) / 0xFFFF) * 1000; /* in uV */
	return ret;
}

static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
{
	int ret;
	u8 datar[2];
	s32 value;

	ret = ltc294x_read_regs(info->client,
		LTC294X_REG_CURRENT_MSB, &datar[0], 2);
	value = (datar[0] << 8) | datar[1];
	value -= 0x7FFF;
	/* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
	 * the formula below keeps everything in s32 range while preserving
	 * enough digits */
	*val = 1000 * ((60000 * value) / (info->r_sense * 0x7FFF)); /* in uA */
	return ret;
}

static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
{
	int ret;
	u8 datar[2];
	u32 value;

	ret = ltc294x_read_regs(info->client,
		LTC294X_REG_TEMPERATURE_MSB, &datar[0], 2);
	value = (datar[0] << 8) | datar[1];
	/* Full-scale is 510 Kelvin, convert to centidegrees  */
	*val = (((51000 * value) / 0xFFFF) - 27215);
	return ret;
}

static int ltc294x_get_property(struct power_supply *psy,
				enum power_supply_property prop,
				union power_supply_propval *val)
{
	struct ltc294x_info *info = power_supply_get_drvdata(psy);

	switch (prop) {
	case POWER_SUPPLY_PROP_CHARGE_NOW:
		return ltc294x_get_charge_now(info, &val->intval);
	case POWER_SUPPLY_PROP_CHARGE_COUNTER:
		return ltc294x_get_charge_counter(info, &val->intval);
	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
		return ltc294x_get_voltage(info, &val->intval);
	case POWER_SUPPLY_PROP_CURRENT_NOW:
		return ltc294x_get_current(info, &val->intval);
	case POWER_SUPPLY_PROP_TEMP:
		return ltc294x_get_temperature(info, &val->intval);
	default:
		return -EINVAL;
	}
}

static int ltc294x_set_property(struct power_supply *psy,
	enum power_supply_property psp,
	const union power_supply_propval *val)
{
	struct ltc294x_info *info = power_supply_get_drvdata(psy);

	switch (psp) {
	case POWER_SUPPLY_PROP_CHARGE_NOW:
		return ltc294x_set_charge_now(info, val->intval);
	default:
		return -EPERM;
	}
}

static int ltc294x_property_is_writeable(
	struct power_supply *psy, enum power_supply_property psp)
{
	switch (psp) {
	case POWER_SUPPLY_PROP_CHARGE_NOW:
		return 1;
	default:
		return 0;
	}
}

static void ltc294x_update(struct ltc294x_info *info)
{
	int charge = ltc294x_read_charge_register(info);

	if (charge != info->charge) {
		info->charge = charge;
		power_supply_changed(info->supply);
	}
}

static void ltc294x_work(struct work_struct *work)
{
	struct ltc294x_info *info;

	info = container_of(work, struct ltc294x_info, work.work);
	ltc294x_update(info);
	schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
}

static enum power_supply_property ltc294x_properties[] = {
	POWER_SUPPLY_PROP_CHARGE_COUNTER,
	POWER_SUPPLY_PROP_CHARGE_NOW,
	POWER_SUPPLY_PROP_VOLTAGE_NOW,
	POWER_SUPPLY_PROP_CURRENT_NOW,
	POWER_SUPPLY_PROP_TEMP,
};

static int ltc294x_i2c_remove(struct i2c_client *client)
{
	struct ltc294x_info *info = i2c_get_clientdata(client);

	cancel_delayed_work(&info->work);
	power_supply_unregister(info->supply);
	return 0;
}

static int ltc294x_i2c_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
{
	struct power_supply_config psy_cfg = {};
	struct ltc294x_info *info;
	int ret;
	u32 prescaler_exp;
	s32 r_sense;
	struct device_node *np;

	info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
	if (info == NULL)
		return -ENOMEM;

	i2c_set_clientdata(client, info);

	np = of_node_get(client->dev.of_node);

	info->num_regs = id->driver_data;
	info->supply_desc.name = np->name;

	/* r_sense can be negative, when sense+ is connected to the battery
	 * instead of the sense-. This results in reversed measurements. */
	ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
	if (ret < 0) {
		dev_err(&client->dev,
			"Could not find lltc,resistor-sense in devicetree\n");
		return ret;
	}
	info->r_sense = r_sense;

	ret = of_property_read_u32(np, "lltc,prescaler-exponent",
		&prescaler_exp);
	if (ret < 0) {
		dev_warn(&client->dev,
			"lltc,prescaler-exponent not in devicetree\n");
		prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
	}

	if (info->num_regs == LTC2943_NUM_REGS) {
		if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
			prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
		info->Qlsb = ((340 * 50000) / r_sense) /
				(4096 / (1 << (2*prescaler_exp)));
	} else {
		if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
			prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
		info->Qlsb = ((85 * 50000) / r_sense) /
				(128 / (1 << prescaler_exp));
	}

	info->client = client;
	info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
	info->supply_desc.properties = ltc294x_properties;
	if (info->num_regs >= LTC294X_REG_TEMPERATURE_LSB)
		info->supply_desc.num_properties =
			ARRAY_SIZE(ltc294x_properties);
	else if (info->num_regs >= LTC294X_REG_CURRENT_LSB)
		info->supply_desc.num_properties =
			ARRAY_SIZE(ltc294x_properties) - 1;
	else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
		info->supply_desc.num_properties =
			ARRAY_SIZE(ltc294x_properties) - 2;
	else
		info->supply_desc.num_properties =
			ARRAY_SIZE(ltc294x_properties) - 3;
	info->supply_desc.get_property = ltc294x_get_property;
	info->supply_desc.set_property = ltc294x_set_property;
	info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
	info->supply_desc.external_power_changed	= NULL;

	psy_cfg.drv_data = info;

	INIT_DELAYED_WORK(&info->work, ltc294x_work);

	ret = ltc294x_reset(info, prescaler_exp);
	if (ret < 0) {
		dev_err(&client->dev, "Communication with chip failed\n");
		return ret;
	}

	info->supply = power_supply_register(&client->dev, &info->supply_desc,
					     &psy_cfg);
	if (IS_ERR(info->supply)) {
		dev_err(&client->dev, "failed to register ltc2941\n");
		return PTR_ERR(info->supply);
	} else {
		schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
	}

	return 0;
}

#ifdef CONFIG_PM_SLEEP

static int ltc294x_suspend(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct ltc294x_info *info = i2c_get_clientdata(client);

	cancel_delayed_work(&info->work);
	return 0;
}

static int ltc294x_resume(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct ltc294x_info *info = i2c_get_clientdata(client);

	schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
	return 0;
}

static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
#define LTC294X_PM_OPS (&ltc294x_pm_ops)

#else
#define LTC294X_PM_OPS NULL
#endif /* CONFIG_PM_SLEEP */


static const struct i2c_device_id ltc294x_i2c_id[] = {
	{"ltc2941", LTC2941_NUM_REGS},
	{"ltc2943", LTC2943_NUM_REGS},
	{ },
};
MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);

static struct i2c_driver ltc294x_driver = {
	.driver = {
		.name	= "LTC2941",
		.pm	= LTC294X_PM_OPS,
	},
	.probe		= ltc294x_i2c_probe,
	.remove		= ltc294x_i2c_remove,
	.id_table	= ltc294x_i2c_id,
};
module_i2c_driver(ltc294x_driver);

MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
MODULE_DESCRIPTION("LTC2941/LTC2943 Battery Gas Gauge IC driver");
MODULE_LICENSE("GPL");