1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * I2C client/driver for the Linear Technology LTC2941, LTC2942, LTC2943
4  * and LTC2944 Battery Gas Gauge IC
5  *
6  * Copyright (C) 2014 Topic Embedded Systems
7  *
8  * Author: Auryn Verwegen
9  * Author: Mike Looijmans
10  */
11 #include <linux/devm-helpers.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/of_device.h>
15 #include <linux/types.h>
16 #include <linux/errno.h>
17 #include <linux/swab.h>
18 #include <linux/i2c.h>
19 #include <linux/delay.h>
20 #include <linux/power_supply.h>
21 #include <linux/slab.h>
22 
23 #define I16_MSB(x)			((x >> 8) & 0xFF)
24 #define I16_LSB(x)			(x & 0xFF)
25 
26 #define LTC294X_WORK_DELAY		10	/* Update delay in seconds */
27 
28 #define LTC294X_MAX_VALUE		0xFFFF
29 #define LTC294X_MID_SUPPLY		0x7FFF
30 
31 #define LTC2941_MAX_PRESCALER_EXP	7
32 #define LTC2943_MAX_PRESCALER_EXP	6
33 
34 enum ltc294x_reg {
35 	LTC294X_REG_STATUS		= 0x00,
36 	LTC294X_REG_CONTROL		= 0x01,
37 	LTC294X_REG_ACC_CHARGE_MSB	= 0x02,
38 	LTC294X_REG_ACC_CHARGE_LSB	= 0x03,
39 	LTC294X_REG_CHARGE_THR_HIGH_MSB	= 0x04,
40 	LTC294X_REG_CHARGE_THR_HIGH_LSB	= 0x05,
41 	LTC294X_REG_CHARGE_THR_LOW_MSB	= 0x06,
42 	LTC294X_REG_CHARGE_THR_LOW_LSB	= 0x07,
43 	LTC294X_REG_VOLTAGE_MSB		= 0x08,
44 	LTC294X_REG_VOLTAGE_LSB		= 0x09,
45 	LTC2942_REG_TEMPERATURE_MSB	= 0x0C,
46 	LTC2942_REG_TEMPERATURE_LSB	= 0x0D,
47 	LTC2943_REG_CURRENT_MSB		= 0x0E,
48 	LTC2943_REG_CURRENT_LSB		= 0x0F,
49 	LTC2943_REG_TEMPERATURE_MSB	= 0x14,
50 	LTC2943_REG_TEMPERATURE_LSB	= 0x15,
51 };
52 
53 enum ltc294x_id {
54 	LTC2941_ID,
55 	LTC2942_ID,
56 	LTC2943_ID,
57 	LTC2944_ID,
58 };
59 
60 #define LTC2941_REG_STATUS_CHIP_ID	BIT(7)
61 
62 #define LTC2942_REG_CONTROL_MODE_SCAN	(BIT(7) | BIT(6))
63 #define LTC2943_REG_CONTROL_MODE_SCAN	BIT(7)
64 #define LTC294X_REG_CONTROL_PRESCALER_MASK	(BIT(5) | BIT(4) | BIT(3))
65 #define LTC294X_REG_CONTROL_SHUTDOWN_MASK	(BIT(0))
66 #define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
67 	((x << 3) & LTC294X_REG_CONTROL_PRESCALER_MASK)
68 #define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED	0
69 #define LTC294X_REG_CONTROL_ADC_DISABLE(x)	((x) & ~(BIT(7) | BIT(6)))
70 
71 struct ltc294x_info {
72 	struct i2c_client *client;	/* I2C Client pointer */
73 	struct power_supply *supply;	/* Supply pointer */
74 	struct power_supply_desc supply_desc;	/* Supply description */
75 	struct delayed_work work;	/* Work scheduler */
76 	enum ltc294x_id id;		/* Chip type */
77 	int charge;	/* Last charge register content */
78 	int r_sense;	/* mOhm */
79 	int Qlsb;	/* nAh */
80 };
81 
convert_bin_to_uAh(const struct ltc294x_info * info,int Q)82 static inline int convert_bin_to_uAh(
83 	const struct ltc294x_info *info, int Q)
84 {
85 	return ((Q * (info->Qlsb / 10))) / 100;
86 }
87 
convert_uAh_to_bin(const struct ltc294x_info * info,int uAh)88 static inline int convert_uAh_to_bin(
89 	const struct ltc294x_info *info, int uAh)
90 {
91 	int Q;
92 
93 	Q = (uAh * 100) / (info->Qlsb/10);
94 	return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
95 }
96 
ltc294x_read_regs(struct i2c_client * client,enum ltc294x_reg reg,u8 * buf,int num_regs)97 static int ltc294x_read_regs(struct i2c_client *client,
98 	enum ltc294x_reg reg, u8 *buf, int num_regs)
99 {
100 	int ret;
101 	struct i2c_msg msgs[2] = { };
102 	u8 reg_start = reg;
103 
104 	msgs[0].addr	= client->addr;
105 	msgs[0].len	= 1;
106 	msgs[0].buf	= &reg_start;
107 
108 	msgs[1].addr	= client->addr;
109 	msgs[1].len	= num_regs;
110 	msgs[1].buf	= buf;
111 	msgs[1].flags	= I2C_M_RD;
112 
113 	ret = i2c_transfer(client->adapter, &msgs[0], 2);
114 	if (ret < 0) {
115 		dev_err(&client->dev, "ltc2941 read_reg failed!\n");
116 		return ret;
117 	}
118 
119 	dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
120 		__func__, reg, num_regs, *buf);
121 
122 	return 0;
123 }
124 
ltc294x_write_regs(struct i2c_client * client,enum ltc294x_reg reg,const u8 * buf,int num_regs)125 static int ltc294x_write_regs(struct i2c_client *client,
126 	enum ltc294x_reg reg, const u8 *buf, int num_regs)
127 {
128 	int ret;
129 	u8 reg_start = reg;
130 
131 	ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
132 	if (ret < 0) {
133 		dev_err(&client->dev, "ltc2941 write_reg failed!\n");
134 		return ret;
135 	}
136 
137 	dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
138 		__func__, reg, num_regs, *buf);
139 
140 	return 0;
141 }
142 
ltc294x_reset(const struct ltc294x_info * info,int prescaler_exp)143 static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
144 {
145 	int ret;
146 	u8 value;
147 	u8 control;
148 
149 	/* Read status and control registers */
150 	ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
151 	if (ret < 0) {
152 		dev_err(&info->client->dev,
153 			"Could not read registers from device\n");
154 		goto error_exit;
155 	}
156 
157 	control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
158 				LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
159 	/* Put device into "monitor" mode */
160 	switch (info->id) {
161 	case LTC2942_ID:	/* 2942 measures every 2 sec */
162 		control |= LTC2942_REG_CONTROL_MODE_SCAN;
163 		break;
164 	case LTC2943_ID:
165 	case LTC2944_ID:	/* 2943 and 2944 measure every 10 sec */
166 		control |= LTC2943_REG_CONTROL_MODE_SCAN;
167 		break;
168 	default:
169 		break;
170 	}
171 
172 	if (value != control) {
173 		ret = ltc294x_write_regs(info->client,
174 			LTC294X_REG_CONTROL, &control, 1);
175 		if (ret < 0) {
176 			dev_err(&info->client->dev,
177 				"Could not write register\n");
178 			goto error_exit;
179 		}
180 	}
181 
182 	return 0;
183 
184 error_exit:
185 	return ret;
186 }
187 
ltc294x_read_charge_register(const struct ltc294x_info * info,enum ltc294x_reg reg)188 static int ltc294x_read_charge_register(const struct ltc294x_info *info,
189 					enum ltc294x_reg reg)
190  {
191 	int ret;
192 	u8 datar[2];
193 
194 	ret = ltc294x_read_regs(info->client, reg, &datar[0], 2);
195 	if (ret < 0)
196 		return ret;
197 	return (datar[0] << 8) + datar[1];
198 }
199 
ltc294x_get_charge(const struct ltc294x_info * info,enum ltc294x_reg reg,int * val)200 static int ltc294x_get_charge(const struct ltc294x_info *info,
201 				enum ltc294x_reg reg, int *val)
202 {
203 	int value = ltc294x_read_charge_register(info, reg);
204 
205 	if (value < 0)
206 		return value;
207 	/* When r_sense < 0, this counts up when the battery discharges */
208 	if (info->Qlsb < 0)
209 		value -= 0xFFFF;
210 	*val = convert_bin_to_uAh(info, value);
211 	return 0;
212 }
213 
ltc294x_set_charge_now(const struct ltc294x_info * info,int val)214 static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
215 {
216 	int ret;
217 	u8 dataw[2];
218 	u8 ctrl_reg;
219 	s32 value;
220 
221 	value = convert_uAh_to_bin(info, val);
222 	/* Direction depends on how sense+/- were connected */
223 	if (info->Qlsb < 0)
224 		value += 0xFFFF;
225 	if ((value < 0) || (value > 0xFFFF)) /* input validation */
226 		return -EINVAL;
227 
228 	/* Read control register */
229 	ret = ltc294x_read_regs(info->client,
230 		LTC294X_REG_CONTROL, &ctrl_reg, 1);
231 	if (ret < 0)
232 		return ret;
233 	/* Disable analog section */
234 	ctrl_reg |= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
235 	ret = ltc294x_write_regs(info->client,
236 		LTC294X_REG_CONTROL, &ctrl_reg, 1);
237 	if (ret < 0)
238 		return ret;
239 	/* Set new charge value */
240 	dataw[0] = I16_MSB(value);
241 	dataw[1] = I16_LSB(value);
242 	ret = ltc294x_write_regs(info->client,
243 		LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
244 	if (ret < 0)
245 		goto error_exit;
246 	/* Enable analog section */
247 error_exit:
248 	ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
249 	ret = ltc294x_write_regs(info->client,
250 		LTC294X_REG_CONTROL, &ctrl_reg, 1);
251 
252 	return ret < 0 ? ret : 0;
253 }
254 
ltc294x_set_charge_thr(const struct ltc294x_info * info,enum ltc294x_reg reg,int val)255 static int ltc294x_set_charge_thr(const struct ltc294x_info *info,
256 					enum ltc294x_reg reg, int val)
257 {
258 	u8 dataw[2];
259 	s32 value;
260 
261 	value = convert_uAh_to_bin(info, val);
262 	/* Direction depends on how sense+/- were connected */
263 	if (info->Qlsb < 0)
264 		value += 0xFFFF;
265 	if ((value < 0) || (value > 0xFFFF)) /* input validation */
266 		return -EINVAL;
267 
268 	/* Set new charge value */
269 	dataw[0] = I16_MSB(value);
270 	dataw[1] = I16_LSB(value);
271 	return ltc294x_write_regs(info->client, reg, &dataw[0], 2);
272 }
273 
ltc294x_get_charge_counter(const struct ltc294x_info * info,int * val)274 static int ltc294x_get_charge_counter(
275 	const struct ltc294x_info *info, int *val)
276 {
277 	int value = ltc294x_read_charge_register(info, LTC294X_REG_ACC_CHARGE_MSB);
278 
279 	if (value < 0)
280 		return value;
281 	value -= LTC294X_MID_SUPPLY;
282 	*val = convert_bin_to_uAh(info, value);
283 	return 0;
284 }
285 
ltc294x_get_voltage(const struct ltc294x_info * info,int * val)286 static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
287 {
288 	int ret;
289 	u8 datar[2];
290 	u32 value;
291 
292 	ret = ltc294x_read_regs(info->client,
293 		LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
294 	value = (datar[0] << 8) | datar[1];
295 	switch (info->id) {
296 	case LTC2943_ID:
297 		value *= 23600 * 2;
298 		value /= 0xFFFF;
299 		value *= 1000 / 2;
300 		break;
301 	case LTC2944_ID:
302 		value *= 70800 / 5*4;
303 		value /= 0xFFFF;
304 		value *= 1000 * 5/4;
305 		break;
306 	default:
307 		value *= 6000 * 10;
308 		value /= 0xFFFF;
309 		value *= 1000 / 10;
310 		break;
311 	}
312 	*val = value;
313 	return ret;
314 }
315 
ltc294x_get_current(const struct ltc294x_info * info,int * val)316 static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
317 {
318 	int ret;
319 	u8 datar[2];
320 	s32 value;
321 
322 	ret = ltc294x_read_regs(info->client,
323 		LTC2943_REG_CURRENT_MSB, &datar[0], 2);
324 	value = (datar[0] << 8) | datar[1];
325 	value -= 0x7FFF;
326 	if (info->id == LTC2944_ID)
327 		value *= 64000;
328 	else
329 		value *= 60000;
330 	/* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
331 	 * the formula below keeps everything in s32 range while preserving
332 	 * enough digits */
333 	*val = 1000 * (value / (info->r_sense * 0x7FFF)); /* in uA */
334 	return ret;
335 }
336 
ltc294x_get_temperature(const struct ltc294x_info * info,int * val)337 static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
338 {
339 	enum ltc294x_reg reg;
340 	int ret;
341 	u8 datar[2];
342 	u32 value;
343 
344 	if (info->id == LTC2942_ID) {
345 		reg = LTC2942_REG_TEMPERATURE_MSB;
346 		value = 6000;	/* Full-scale is 600 Kelvin */
347 	} else {
348 		reg = LTC2943_REG_TEMPERATURE_MSB;
349 		value = 5100;	/* Full-scale is 510 Kelvin */
350 	}
351 	ret = ltc294x_read_regs(info->client, reg, &datar[0], 2);
352 	value *= (datar[0] << 8) | datar[1];
353 	/* Convert to tenths of degree Celsius */
354 	*val = value / 0xFFFF - 2722;
355 	return ret;
356 }
357 
ltc294x_get_property(struct power_supply * psy,enum power_supply_property prop,union power_supply_propval * val)358 static int ltc294x_get_property(struct power_supply *psy,
359 				enum power_supply_property prop,
360 				union power_supply_propval *val)
361 {
362 	struct ltc294x_info *info = power_supply_get_drvdata(psy);
363 
364 	switch (prop) {
365 	case POWER_SUPPLY_PROP_CHARGE_FULL:
366 		return ltc294x_get_charge(info, LTC294X_REG_CHARGE_THR_HIGH_MSB,
367 						&val->intval);
368 	case POWER_SUPPLY_PROP_CHARGE_EMPTY:
369 		return ltc294x_get_charge(info, LTC294X_REG_CHARGE_THR_LOW_MSB,
370 						&val->intval);
371 	case POWER_SUPPLY_PROP_CHARGE_NOW:
372 		return ltc294x_get_charge(info, LTC294X_REG_ACC_CHARGE_MSB,
373 						&val->intval);
374 	case POWER_SUPPLY_PROP_CHARGE_COUNTER:
375 		return ltc294x_get_charge_counter(info, &val->intval);
376 	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
377 		return ltc294x_get_voltage(info, &val->intval);
378 	case POWER_SUPPLY_PROP_CURRENT_NOW:
379 		return ltc294x_get_current(info, &val->intval);
380 	case POWER_SUPPLY_PROP_TEMP:
381 		return ltc294x_get_temperature(info, &val->intval);
382 	default:
383 		return -EINVAL;
384 	}
385 }
386 
ltc294x_set_property(struct power_supply * psy,enum power_supply_property psp,const union power_supply_propval * val)387 static int ltc294x_set_property(struct power_supply *psy,
388 	enum power_supply_property psp,
389 	const union power_supply_propval *val)
390 {
391 	struct ltc294x_info *info = power_supply_get_drvdata(psy);
392 
393 	switch (psp) {
394 	case POWER_SUPPLY_PROP_CHARGE_FULL:
395 		return ltc294x_set_charge_thr(info,
396 			LTC294X_REG_CHARGE_THR_HIGH_MSB, val->intval);
397 	case POWER_SUPPLY_PROP_CHARGE_EMPTY:
398 		return ltc294x_set_charge_thr(info,
399 			LTC294X_REG_CHARGE_THR_LOW_MSB, val->intval);
400 	case POWER_SUPPLY_PROP_CHARGE_NOW:
401 		return ltc294x_set_charge_now(info, val->intval);
402 	default:
403 		return -EPERM;
404 	}
405 }
406 
ltc294x_property_is_writeable(struct power_supply * psy,enum power_supply_property psp)407 static int ltc294x_property_is_writeable(
408 	struct power_supply *psy, enum power_supply_property psp)
409 {
410 	switch (psp) {
411 	case POWER_SUPPLY_PROP_CHARGE_FULL:
412 	case POWER_SUPPLY_PROP_CHARGE_EMPTY:
413 	case POWER_SUPPLY_PROP_CHARGE_NOW:
414 		return 1;
415 	default:
416 		return 0;
417 	}
418 }
419 
ltc294x_update(struct ltc294x_info * info)420 static void ltc294x_update(struct ltc294x_info *info)
421 {
422 	int charge = ltc294x_read_charge_register(info, LTC294X_REG_ACC_CHARGE_MSB);
423 
424 	if (charge != info->charge) {
425 		info->charge = charge;
426 		power_supply_changed(info->supply);
427 	}
428 }
429 
ltc294x_work(struct work_struct * work)430 static void ltc294x_work(struct work_struct *work)
431 {
432 	struct ltc294x_info *info;
433 
434 	info = container_of(work, struct ltc294x_info, work.work);
435 	ltc294x_update(info);
436 	schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
437 }
438 
439 static enum power_supply_property ltc294x_properties[] = {
440 	POWER_SUPPLY_PROP_CHARGE_COUNTER,
441 	POWER_SUPPLY_PROP_CHARGE_FULL,
442 	POWER_SUPPLY_PROP_CHARGE_EMPTY,
443 	POWER_SUPPLY_PROP_CHARGE_NOW,
444 	POWER_SUPPLY_PROP_VOLTAGE_NOW,
445 	POWER_SUPPLY_PROP_TEMP,
446 	POWER_SUPPLY_PROP_CURRENT_NOW,
447 };
448 
ltc294x_i2c_probe(struct i2c_client * client,const struct i2c_device_id * id)449 static int ltc294x_i2c_probe(struct i2c_client *client,
450 	const struct i2c_device_id *id)
451 {
452 	struct power_supply_config psy_cfg = {};
453 	struct ltc294x_info *info;
454 	struct device_node *np;
455 	int ret;
456 	u32 prescaler_exp;
457 	s32 r_sense;
458 	u8 status;
459 
460 	info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
461 	if (info == NULL)
462 		return -ENOMEM;
463 
464 	i2c_set_clientdata(client, info);
465 
466 	np = of_node_get(client->dev.of_node);
467 
468 	info->id = (enum ltc294x_id) (uintptr_t) of_device_get_match_data(
469 							&client->dev);
470 	info->supply_desc.name = np->name;
471 
472 	/* r_sense can be negative, when sense+ is connected to the battery
473 	 * instead of the sense-. This results in reversed measurements. */
474 	ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
475 	if (ret < 0) {
476 		dev_err(&client->dev,
477 			"Could not find lltc,resistor-sense in devicetree\n");
478 		return ret;
479 	}
480 	info->r_sense = r_sense;
481 
482 	ret = of_property_read_u32(np, "lltc,prescaler-exponent",
483 		&prescaler_exp);
484 	if (ret < 0) {
485 		dev_warn(&client->dev,
486 			"lltc,prescaler-exponent not in devicetree\n");
487 		prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
488 	}
489 
490 	if (info->id == LTC2943_ID) {
491 		if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
492 			prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
493 		info->Qlsb = ((340 * 50000) / r_sense) /
494 				(4096 / (1 << (2*prescaler_exp)));
495 	} else {
496 		if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
497 			prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
498 		info->Qlsb = ((85 * 50000) / r_sense) /
499 				(128 / (1 << prescaler_exp));
500 	}
501 
502 	/* Read status register to check for LTC2942 */
503 	if (info->id == LTC2941_ID || info->id == LTC2942_ID) {
504 		ret = ltc294x_read_regs(client, LTC294X_REG_STATUS, &status, 1);
505 		if (ret < 0) {
506 			dev_err(&client->dev,
507 				"Could not read status register\n");
508 			return ret;
509 		}
510 		if (status & LTC2941_REG_STATUS_CHIP_ID)
511 			info->id = LTC2941_ID;
512 		else
513 			info->id = LTC2942_ID;
514 	}
515 
516 	info->client = client;
517 	info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
518 	info->supply_desc.properties = ltc294x_properties;
519 	switch (info->id) {
520 	case LTC2944_ID:
521 	case LTC2943_ID:
522 		info->supply_desc.num_properties =
523 			ARRAY_SIZE(ltc294x_properties);
524 		break;
525 	case LTC2942_ID:
526 		info->supply_desc.num_properties =
527 			ARRAY_SIZE(ltc294x_properties) - 1;
528 		break;
529 	case LTC2941_ID:
530 	default:
531 		info->supply_desc.num_properties =
532 			ARRAY_SIZE(ltc294x_properties) - 3;
533 		break;
534 	}
535 	info->supply_desc.get_property = ltc294x_get_property;
536 	info->supply_desc.set_property = ltc294x_set_property;
537 	info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
538 	info->supply_desc.external_power_changed	= NULL;
539 
540 	psy_cfg.drv_data = info;
541 
542 	ret = devm_delayed_work_autocancel(&client->dev, &info->work,
543 					   ltc294x_work);
544 	if (ret)
545 		return ret;
546 
547 	ret = ltc294x_reset(info, prescaler_exp);
548 	if (ret < 0) {
549 		dev_err(&client->dev, "Communication with chip failed\n");
550 		return ret;
551 	}
552 
553 	info->supply = devm_power_supply_register(&client->dev,
554 						  &info->supply_desc, &psy_cfg);
555 	if (IS_ERR(info->supply)) {
556 		dev_err(&client->dev, "failed to register ltc2941\n");
557 		return PTR_ERR(info->supply);
558 	} else {
559 		schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
560 	}
561 
562 	return 0;
563 }
564 
ltc294x_i2c_shutdown(struct i2c_client * client)565 static void ltc294x_i2c_shutdown(struct i2c_client *client)
566 {
567 	struct ltc294x_info *info = i2c_get_clientdata(client);
568 	int ret;
569 	u8 value;
570 	u8 control;
571 
572 	/* The LTC2941 does not need any special handling */
573 	if (info->id == LTC2941_ID)
574 		return;
575 
576 	/* Read control register */
577 	ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
578 	if (ret < 0)
579 		return;
580 
581 	/* Disable continuous ADC conversion as this drains the battery */
582 	control = LTC294X_REG_CONTROL_ADC_DISABLE(value);
583 	if (control != value)
584 		ltc294x_write_regs(info->client, LTC294X_REG_CONTROL,
585 			&control, 1);
586 }
587 
588 #ifdef CONFIG_PM_SLEEP
589 
ltc294x_suspend(struct device * dev)590 static int ltc294x_suspend(struct device *dev)
591 {
592 	struct i2c_client *client = to_i2c_client(dev);
593 	struct ltc294x_info *info = i2c_get_clientdata(client);
594 
595 	cancel_delayed_work(&info->work);
596 	return 0;
597 }
598 
ltc294x_resume(struct device * dev)599 static int ltc294x_resume(struct device *dev)
600 {
601 	struct i2c_client *client = to_i2c_client(dev);
602 	struct ltc294x_info *info = i2c_get_clientdata(client);
603 
604 	schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
605 	return 0;
606 }
607 
608 static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
609 #define LTC294X_PM_OPS (&ltc294x_pm_ops)
610 
611 #else
612 #define LTC294X_PM_OPS NULL
613 #endif /* CONFIG_PM_SLEEP */
614 
615 
616 static const struct i2c_device_id ltc294x_i2c_id[] = {
617 	{ "ltc2941", LTC2941_ID, },
618 	{ "ltc2942", LTC2942_ID, },
619 	{ "ltc2943", LTC2943_ID, },
620 	{ "ltc2944", LTC2944_ID, },
621 	{ },
622 };
623 MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);
624 
625 static const struct of_device_id ltc294x_i2c_of_match[] = {
626 	{
627 		.compatible = "lltc,ltc2941",
628 		.data = (void *)LTC2941_ID,
629 	},
630 	{
631 		.compatible = "lltc,ltc2942",
632 		.data = (void *)LTC2942_ID,
633 	},
634 	{
635 		.compatible = "lltc,ltc2943",
636 		.data = (void *)LTC2943_ID,
637 	},
638 	{
639 		.compatible = "lltc,ltc2944",
640 		.data = (void *)LTC2944_ID,
641 	},
642 	{ },
643 };
644 MODULE_DEVICE_TABLE(of, ltc294x_i2c_of_match);
645 
646 static struct i2c_driver ltc294x_driver = {
647 	.driver = {
648 		.name	= "LTC2941",
649 		.of_match_table = ltc294x_i2c_of_match,
650 		.pm	= LTC294X_PM_OPS,
651 	},
652 	.probe		= ltc294x_i2c_probe,
653 	.shutdown	= ltc294x_i2c_shutdown,
654 	.id_table	= ltc294x_i2c_id,
655 };
656 module_i2c_driver(ltc294x_driver);
657 
658 MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
659 MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
660 MODULE_DESCRIPTION("LTC2941/LTC2942/LTC2943/LTC2944 Battery Gas Gauge IC driver");
661 MODULE_LICENSE("GPL");
662