2 * I2C client/driver for the Linear Technology LTC2941, LTC2942, LTC2943
3 * and LTC2944 Battery Gas Gauge IC
5 * Copyright (C) 2014 Topic Embedded Systems
7 * Author: Auryn Verwegen
8 * Author: Mike Looijmans
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/of_device.h>
13 #include <linux/types.h>
14 #include <linux/errno.h>
15 #include <linux/swab.h>
16 #include <linux/i2c.h>
17 #include <linux/delay.h>
18 #include <linux/power_supply.h>
19 #include <linux/slab.h>
21 #define I16_MSB(x) ((x >> 8) & 0xFF)
22 #define I16_LSB(x) (x & 0xFF)
24 #define LTC294X_WORK_DELAY 10 /* Update delay in seconds */
26 #define LTC294X_MAX_VALUE 0xFFFF
27 #define LTC294X_MID_SUPPLY 0x7FFF
29 #define LTC2941_MAX_PRESCALER_EXP 7
30 #define LTC2943_MAX_PRESCALER_EXP 6
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_CHARGE_THR_HIGH_MSB = 0x04,
38 LTC294X_REG_CHARGE_THR_HIGH_LSB = 0x05,
39 LTC294X_REG_CHARGE_THR_LOW_MSB = 0x06,
40 LTC294X_REG_CHARGE_THR_LOW_LSB = 0x07,
41 LTC294X_REG_VOLTAGE_MSB = 0x08,
42 LTC294X_REG_VOLTAGE_LSB = 0x09,
43 LTC2942_REG_TEMPERATURE_MSB = 0x0C,
44 LTC2942_REG_TEMPERATURE_LSB = 0x0D,
45 LTC2943_REG_CURRENT_MSB = 0x0E,
46 LTC2943_REG_CURRENT_LSB = 0x0F,
47 LTC2943_REG_TEMPERATURE_MSB = 0x14,
48 LTC2943_REG_TEMPERATURE_LSB = 0x15,
58 #define LTC2941_REG_STATUS_CHIP_ID BIT(7)
60 #define LTC2942_REG_CONTROL_MODE_SCAN (BIT(7) | BIT(6))
61 #define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
62 #define LTC294X_REG_CONTROL_PRESCALER_MASK (BIT(5) | BIT(4) | BIT(3))
63 #define LTC294X_REG_CONTROL_SHUTDOWN_MASK (BIT(0))
64 #define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
65 ((x << 3) & LTC294X_REG_CONTROL_PRESCALER_MASK)
66 #define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED 0
67 #define LTC294X_REG_CONTROL_ADC_DISABLE(x) ((x) & ~(BIT(7) | BIT(6)))
70 struct i2c_client *client; /* I2C Client pointer */
71 struct power_supply *supply; /* Supply pointer */
72 struct power_supply_desc supply_desc; /* Supply description */
73 struct delayed_work work; /* Work scheduler */
74 enum ltc294x_id id; /* Chip type */
75 int charge; /* Last charge register content */
76 int r_sense; /* mOhm */
80 static inline int convert_bin_to_uAh(
81 const struct ltc294x_info *info, int Q)
83 return ((Q * (info->Qlsb / 10))) / 100;
86 static inline int convert_uAh_to_bin(
87 const struct ltc294x_info *info, int uAh)
91 Q = (uAh * 100) / (info->Qlsb/10);
92 return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
95 static int ltc294x_read_regs(struct i2c_client *client,
96 enum ltc294x_reg reg, u8 *buf, int num_regs)
99 struct i2c_msg msgs[2] = { };
102 msgs[0].addr = client->addr;
104 msgs[0].buf = ®_start;
106 msgs[1].addr = client->addr;
107 msgs[1].len = num_regs;
109 msgs[1].flags = I2C_M_RD;
111 ret = i2c_transfer(client->adapter, &msgs[0], 2);
113 dev_err(&client->dev, "ltc2941 read_reg failed!\n");
117 dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
118 __func__, reg, num_regs, *buf);
123 static int ltc294x_write_regs(struct i2c_client *client,
124 enum ltc294x_reg reg, const u8 *buf, int num_regs)
129 ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
131 dev_err(&client->dev, "ltc2941 write_reg failed!\n");
135 dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
136 __func__, reg, num_regs, *buf);
141 static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
147 /* Read status and control registers */
148 ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
150 dev_err(&info->client->dev,
151 "Could not read registers from device\n");
155 control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
156 LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
157 /* Put device into "monitor" mode */
159 case LTC2942_ID: /* 2942 measures every 2 sec */
160 control |= LTC2942_REG_CONTROL_MODE_SCAN;
163 case LTC2944_ID: /* 2943 and 2944 measure every 10 sec */
164 control |= LTC2943_REG_CONTROL_MODE_SCAN;
170 if (value != control) {
171 ret = ltc294x_write_regs(info->client,
172 LTC294X_REG_CONTROL, &control, 1);
174 dev_err(&info->client->dev,
175 "Could not write register\n");
186 static int ltc294x_read_charge_register(const struct ltc294x_info *info,
187 enum ltc294x_reg reg)
192 ret = ltc294x_read_regs(info->client, reg, &datar[0], 2);
195 return (datar[0] << 8) + datar[1];
198 static int ltc294x_get_charge(const struct ltc294x_info *info,
199 enum ltc294x_reg reg, int *val)
201 int value = ltc294x_read_charge_register(info, reg);
205 /* When r_sense < 0, this counts up when the battery discharges */
208 *val = convert_bin_to_uAh(info, value);
212 static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
219 value = convert_uAh_to_bin(info, val);
220 /* Direction depends on how sense+/- were connected */
223 if ((value < 0) || (value > 0xFFFF)) /* input validation */
226 /* Read control register */
227 ret = ltc294x_read_regs(info->client,
228 LTC294X_REG_CONTROL, &ctrl_reg, 1);
231 /* Disable analog section */
232 ctrl_reg |= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
233 ret = ltc294x_write_regs(info->client,
234 LTC294X_REG_CONTROL, &ctrl_reg, 1);
237 /* Set new charge value */
238 dataw[0] = I16_MSB(value);
239 dataw[1] = I16_LSB(value);
240 ret = ltc294x_write_regs(info->client,
241 LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
244 /* Enable analog section */
246 ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
247 ret = ltc294x_write_regs(info->client,
248 LTC294X_REG_CONTROL, &ctrl_reg, 1);
250 return ret < 0 ? ret : 0;
253 static int ltc294x_set_charge_thr(const struct ltc294x_info *info,
254 enum ltc294x_reg reg, int val)
259 value = convert_uAh_to_bin(info, val);
260 /* Direction depends on how sense+/- were connected */
263 if ((value < 0) || (value > 0xFFFF)) /* input validation */
266 /* Set new charge value */
267 dataw[0] = I16_MSB(value);
268 dataw[1] = I16_LSB(value);
269 return ltc294x_write_regs(info->client, reg, &dataw[0], 2);
272 static int ltc294x_get_charge_counter(
273 const struct ltc294x_info *info, int *val)
275 int value = ltc294x_read_charge_register(info, LTC294X_REG_ACC_CHARGE_MSB);
279 value -= LTC294X_MID_SUPPLY;
280 *val = convert_bin_to_uAh(info, value);
284 static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
290 ret = ltc294x_read_regs(info->client,
291 LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
292 value = (datar[0] << 8) | datar[1];
300 value *= 70800 / 5*4;
314 static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
320 ret = ltc294x_read_regs(info->client,
321 LTC2943_REG_CURRENT_MSB, &datar[0], 2);
322 value = (datar[0] << 8) | datar[1];
324 if (info->id == LTC2944_ID)
328 /* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
329 * the formula below keeps everything in s32 range while preserving
331 *val = 1000 * (value / (info->r_sense * 0x7FFF)); /* in uA */
335 static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
337 enum ltc294x_reg reg;
342 if (info->id == LTC2942_ID) {
343 reg = LTC2942_REG_TEMPERATURE_MSB;
344 value = 6000; /* Full-scale is 600 Kelvin */
346 reg = LTC2943_REG_TEMPERATURE_MSB;
347 value = 5100; /* Full-scale is 510 Kelvin */
349 ret = ltc294x_read_regs(info->client, reg, &datar[0], 2);
350 value *= (datar[0] << 8) | datar[1];
351 /* Convert to tenths of degree Celsius */
352 *val = value / 0xFFFF - 2722;
356 static int ltc294x_get_property(struct power_supply *psy,
357 enum power_supply_property prop,
358 union power_supply_propval *val)
360 struct ltc294x_info *info = power_supply_get_drvdata(psy);
363 case POWER_SUPPLY_PROP_CHARGE_FULL:
364 return ltc294x_get_charge(info, LTC294X_REG_CHARGE_THR_HIGH_MSB,
366 case POWER_SUPPLY_PROP_CHARGE_EMPTY:
367 return ltc294x_get_charge(info, LTC294X_REG_CHARGE_THR_LOW_MSB,
369 case POWER_SUPPLY_PROP_CHARGE_NOW:
370 return ltc294x_get_charge(info, LTC294X_REG_ACC_CHARGE_MSB,
372 case POWER_SUPPLY_PROP_CHARGE_COUNTER:
373 return ltc294x_get_charge_counter(info, &val->intval);
374 case POWER_SUPPLY_PROP_VOLTAGE_NOW:
375 return ltc294x_get_voltage(info, &val->intval);
376 case POWER_SUPPLY_PROP_CURRENT_NOW:
377 return ltc294x_get_current(info, &val->intval);
378 case POWER_SUPPLY_PROP_TEMP:
379 return ltc294x_get_temperature(info, &val->intval);
385 static int ltc294x_set_property(struct power_supply *psy,
386 enum power_supply_property psp,
387 const union power_supply_propval *val)
389 struct ltc294x_info *info = power_supply_get_drvdata(psy);
392 case POWER_SUPPLY_PROP_CHARGE_FULL:
393 return ltc294x_set_charge_thr(info,
394 LTC294X_REG_CHARGE_THR_HIGH_MSB, val->intval);
395 case POWER_SUPPLY_PROP_CHARGE_EMPTY:
396 return ltc294x_set_charge_thr(info,
397 LTC294X_REG_CHARGE_THR_LOW_MSB, val->intval);
398 case POWER_SUPPLY_PROP_CHARGE_NOW:
399 return ltc294x_set_charge_now(info, val->intval);
405 static int ltc294x_property_is_writeable(
406 struct power_supply *psy, enum power_supply_property psp)
409 case POWER_SUPPLY_PROP_CHARGE_FULL:
410 case POWER_SUPPLY_PROP_CHARGE_EMPTY:
411 case POWER_SUPPLY_PROP_CHARGE_NOW:
418 static void ltc294x_update(struct ltc294x_info *info)
420 int charge = ltc294x_read_charge_register(info, LTC294X_REG_ACC_CHARGE_MSB);
422 if (charge != info->charge) {
423 info->charge = charge;
424 power_supply_changed(info->supply);
428 static void ltc294x_work(struct work_struct *work)
430 struct ltc294x_info *info;
432 info = container_of(work, struct ltc294x_info, work.work);
433 ltc294x_update(info);
434 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
437 static enum power_supply_property ltc294x_properties[] = {
438 POWER_SUPPLY_PROP_CHARGE_COUNTER,
439 POWER_SUPPLY_PROP_CHARGE_FULL,
440 POWER_SUPPLY_PROP_CHARGE_EMPTY,
441 POWER_SUPPLY_PROP_CHARGE_NOW,
442 POWER_SUPPLY_PROP_VOLTAGE_NOW,
443 POWER_SUPPLY_PROP_TEMP,
444 POWER_SUPPLY_PROP_CURRENT_NOW,
447 static int ltc294x_i2c_remove(struct i2c_client *client)
449 struct ltc294x_info *info = i2c_get_clientdata(client);
451 cancel_delayed_work_sync(&info->work);
452 power_supply_unregister(info->supply);
456 static int ltc294x_i2c_probe(struct i2c_client *client,
457 const struct i2c_device_id *id)
459 struct power_supply_config psy_cfg = {};
460 struct ltc294x_info *info;
461 struct device_node *np;
467 info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
471 i2c_set_clientdata(client, info);
473 np = of_node_get(client->dev.of_node);
475 info->id = (enum ltc294x_id)of_device_get_match_data(&client->dev);
476 info->supply_desc.name = np->name;
478 /* r_sense can be negative, when sense+ is connected to the battery
479 * instead of the sense-. This results in reversed measurements. */
480 ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
482 dev_err(&client->dev,
483 "Could not find lltc,resistor-sense in devicetree\n");
486 info->r_sense = r_sense;
488 ret = of_property_read_u32(np, "lltc,prescaler-exponent",
491 dev_warn(&client->dev,
492 "lltc,prescaler-exponent not in devicetree\n");
493 prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
496 if (info->id == LTC2943_ID) {
497 if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
498 prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
499 info->Qlsb = ((340 * 50000) / r_sense) /
500 (4096 / (1 << (2*prescaler_exp)));
502 if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
503 prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
504 info->Qlsb = ((85 * 50000) / r_sense) /
505 (128 / (1 << prescaler_exp));
508 /* Read status register to check for LTC2942 */
509 if (info->id == LTC2941_ID || info->id == LTC2942_ID) {
510 ret = ltc294x_read_regs(client, LTC294X_REG_STATUS, &status, 1);
512 dev_err(&client->dev,
513 "Could not read status register\n");
516 if (status & LTC2941_REG_STATUS_CHIP_ID)
517 info->id = LTC2941_ID;
519 info->id = LTC2942_ID;
522 info->client = client;
523 info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
524 info->supply_desc.properties = ltc294x_properties;
528 info->supply_desc.num_properties =
529 ARRAY_SIZE(ltc294x_properties);
532 info->supply_desc.num_properties =
533 ARRAY_SIZE(ltc294x_properties) - 1;
537 info->supply_desc.num_properties =
538 ARRAY_SIZE(ltc294x_properties) - 3;
541 info->supply_desc.get_property = ltc294x_get_property;
542 info->supply_desc.set_property = ltc294x_set_property;
543 info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
544 info->supply_desc.external_power_changed = NULL;
546 psy_cfg.drv_data = info;
548 INIT_DELAYED_WORK(&info->work, ltc294x_work);
550 ret = ltc294x_reset(info, prescaler_exp);
552 dev_err(&client->dev, "Communication with chip failed\n");
556 info->supply = power_supply_register(&client->dev, &info->supply_desc,
558 if (IS_ERR(info->supply)) {
559 dev_err(&client->dev, "failed to register ltc2941\n");
560 return PTR_ERR(info->supply);
562 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
568 static void ltc294x_i2c_shutdown(struct i2c_client *client)
570 struct ltc294x_info *info = i2c_get_clientdata(client);
575 /* The LTC2941 does not need any special handling */
576 if (info->id == LTC2941_ID)
579 /* Read control register */
580 ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
584 /* Disable continuous ADC conversion as this drains the battery */
585 control = LTC294X_REG_CONTROL_ADC_DISABLE(value);
586 if (control != value)
587 ltc294x_write_regs(info->client, LTC294X_REG_CONTROL,
591 #ifdef CONFIG_PM_SLEEP
593 static int ltc294x_suspend(struct device *dev)
595 struct i2c_client *client = to_i2c_client(dev);
596 struct ltc294x_info *info = i2c_get_clientdata(client);
598 cancel_delayed_work(&info->work);
602 static int ltc294x_resume(struct device *dev)
604 struct i2c_client *client = to_i2c_client(dev);
605 struct ltc294x_info *info = i2c_get_clientdata(client);
607 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
611 static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
612 #define LTC294X_PM_OPS (<c294x_pm_ops)
615 #define LTC294X_PM_OPS NULL
616 #endif /* CONFIG_PM_SLEEP */
619 static const struct i2c_device_id ltc294x_i2c_id[] = {
620 { "ltc2941", LTC2941_ID, },
621 { "ltc2942", LTC2942_ID, },
622 { "ltc2943", LTC2943_ID, },
623 { "ltc2944", LTC2944_ID, },
626 MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);
628 static const struct of_device_id ltc294x_i2c_of_match[] = {
630 .compatible = "lltc,ltc2941",
631 .data = (void *)LTC2941_ID,
634 .compatible = "lltc,ltc2942",
635 .data = (void *)LTC2942_ID,
638 .compatible = "lltc,ltc2943",
639 .data = (void *)LTC2943_ID,
642 .compatible = "lltc,ltc2944",
643 .data = (void *)LTC2944_ID,
647 MODULE_DEVICE_TABLE(of, ltc294x_i2c_of_match);
649 static struct i2c_driver ltc294x_driver = {
652 .of_match_table = ltc294x_i2c_of_match,
653 .pm = LTC294X_PM_OPS,
655 .probe = ltc294x_i2c_probe,
656 .remove = ltc294x_i2c_remove,
657 .shutdown = ltc294x_i2c_shutdown,
658 .id_table = ltc294x_i2c_id,
660 module_i2c_driver(ltc294x_driver);
662 MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
663 MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
664 MODULE_DESCRIPTION("LTC2941/LTC2942/LTC2943/LTC2944 Battery Gas Gauge IC driver");
665 MODULE_LICENSE("GPL");