1 // SPDX-License-Identifier: GPL-2.0-only
3 * I2C client/driver for the Linear Technology LTC2941, LTC2942, LTC2943
4 * and LTC2944 Battery Gas Gauge IC
6 * Copyright (C) 2014 Topic Embedded Systems
8 * Author: Auryn Verwegen
9 * Author: Mike Looijmans
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/of_device.h>
14 #include <linux/types.h>
15 #include <linux/errno.h>
16 #include <linux/swab.h>
17 #include <linux/i2c.h>
18 #include <linux/delay.h>
19 #include <linux/power_supply.h>
20 #include <linux/slab.h>
22 #define I16_MSB(x) ((x >> 8) & 0xFF)
23 #define I16_LSB(x) (x & 0xFF)
25 #define LTC294X_WORK_DELAY 10 /* Update delay in seconds */
27 #define LTC294X_MAX_VALUE 0xFFFF
28 #define LTC294X_MID_SUPPLY 0x7FFF
30 #define LTC2941_MAX_PRESCALER_EXP 7
31 #define LTC2943_MAX_PRESCALER_EXP 6
34 LTC294X_REG_STATUS = 0x00,
35 LTC294X_REG_CONTROL = 0x01,
36 LTC294X_REG_ACC_CHARGE_MSB = 0x02,
37 LTC294X_REG_ACC_CHARGE_LSB = 0x03,
38 LTC294X_REG_CHARGE_THR_HIGH_MSB = 0x04,
39 LTC294X_REG_CHARGE_THR_HIGH_LSB = 0x05,
40 LTC294X_REG_CHARGE_THR_LOW_MSB = 0x06,
41 LTC294X_REG_CHARGE_THR_LOW_LSB = 0x07,
42 LTC294X_REG_VOLTAGE_MSB = 0x08,
43 LTC294X_REG_VOLTAGE_LSB = 0x09,
44 LTC2942_REG_TEMPERATURE_MSB = 0x0C,
45 LTC2942_REG_TEMPERATURE_LSB = 0x0D,
46 LTC2943_REG_CURRENT_MSB = 0x0E,
47 LTC2943_REG_CURRENT_LSB = 0x0F,
48 LTC2943_REG_TEMPERATURE_MSB = 0x14,
49 LTC2943_REG_TEMPERATURE_LSB = 0x15,
59 #define LTC2941_REG_STATUS_CHIP_ID BIT(7)
61 #define LTC2942_REG_CONTROL_MODE_SCAN (BIT(7) | BIT(6))
62 #define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
63 #define LTC294X_REG_CONTROL_PRESCALER_MASK (BIT(5) | BIT(4) | BIT(3))
64 #define LTC294X_REG_CONTROL_SHUTDOWN_MASK (BIT(0))
65 #define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
66 ((x << 3) & LTC294X_REG_CONTROL_PRESCALER_MASK)
67 #define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED 0
68 #define LTC294X_REG_CONTROL_ADC_DISABLE(x) ((x) & ~(BIT(7) | BIT(6)))
71 struct i2c_client *client; /* I2C Client pointer */
72 struct power_supply *supply; /* Supply pointer */
73 struct power_supply_desc supply_desc; /* Supply description */
74 struct delayed_work work; /* Work scheduler */
75 enum ltc294x_id id; /* Chip type */
76 int charge; /* Last charge register content */
77 int r_sense; /* mOhm */
81 static inline int convert_bin_to_uAh(
82 const struct ltc294x_info *info, int Q)
84 return ((Q * (info->Qlsb / 10))) / 100;
87 static inline int convert_uAh_to_bin(
88 const struct ltc294x_info *info, int uAh)
92 Q = (uAh * 100) / (info->Qlsb/10);
93 return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
96 static int ltc294x_read_regs(struct i2c_client *client,
97 enum ltc294x_reg reg, u8 *buf, int num_regs)
100 struct i2c_msg msgs[2] = { };
103 msgs[0].addr = client->addr;
105 msgs[0].buf = ®_start;
107 msgs[1].addr = client->addr;
108 msgs[1].len = num_regs;
110 msgs[1].flags = I2C_M_RD;
112 ret = i2c_transfer(client->adapter, &msgs[0], 2);
114 dev_err(&client->dev, "ltc2941 read_reg failed!\n");
118 dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
119 __func__, reg, num_regs, *buf);
124 static int ltc294x_write_regs(struct i2c_client *client,
125 enum ltc294x_reg reg, const u8 *buf, int num_regs)
130 ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
132 dev_err(&client->dev, "ltc2941 write_reg failed!\n");
136 dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
137 __func__, reg, num_regs, *buf);
142 static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
148 /* Read status and control registers */
149 ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
151 dev_err(&info->client->dev,
152 "Could not read registers from device\n");
156 control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
157 LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
158 /* Put device into "monitor" mode */
160 case LTC2942_ID: /* 2942 measures every 2 sec */
161 control |= LTC2942_REG_CONTROL_MODE_SCAN;
164 case LTC2944_ID: /* 2943 and 2944 measure every 10 sec */
165 control |= LTC2943_REG_CONTROL_MODE_SCAN;
171 if (value != control) {
172 ret = ltc294x_write_regs(info->client,
173 LTC294X_REG_CONTROL, &control, 1);
175 dev_err(&info->client->dev,
176 "Could not write register\n");
187 static int ltc294x_read_charge_register(const struct ltc294x_info *info,
188 enum ltc294x_reg reg)
193 ret = ltc294x_read_regs(info->client, reg, &datar[0], 2);
196 return (datar[0] << 8) + datar[1];
199 static int ltc294x_get_charge(const struct ltc294x_info *info,
200 enum ltc294x_reg reg, int *val)
202 int value = ltc294x_read_charge_register(info, reg);
206 /* When r_sense < 0, this counts up when the battery discharges */
209 *val = convert_bin_to_uAh(info, value);
213 static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
220 value = convert_uAh_to_bin(info, val);
221 /* Direction depends on how sense+/- were connected */
224 if ((value < 0) || (value > 0xFFFF)) /* input validation */
227 /* Read control register */
228 ret = ltc294x_read_regs(info->client,
229 LTC294X_REG_CONTROL, &ctrl_reg, 1);
232 /* Disable analog section */
233 ctrl_reg |= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
234 ret = ltc294x_write_regs(info->client,
235 LTC294X_REG_CONTROL, &ctrl_reg, 1);
238 /* Set new charge value */
239 dataw[0] = I16_MSB(value);
240 dataw[1] = I16_LSB(value);
241 ret = ltc294x_write_regs(info->client,
242 LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
245 /* Enable analog section */
247 ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
248 ret = ltc294x_write_regs(info->client,
249 LTC294X_REG_CONTROL, &ctrl_reg, 1);
251 return ret < 0 ? ret : 0;
254 static int ltc294x_set_charge_thr(const struct ltc294x_info *info,
255 enum ltc294x_reg reg, int val)
260 value = convert_uAh_to_bin(info, val);
261 /* Direction depends on how sense+/- were connected */
264 if ((value < 0) || (value > 0xFFFF)) /* input validation */
267 /* Set new charge value */
268 dataw[0] = I16_MSB(value);
269 dataw[1] = I16_LSB(value);
270 return ltc294x_write_regs(info->client, reg, &dataw[0], 2);
273 static int ltc294x_get_charge_counter(
274 const struct ltc294x_info *info, int *val)
276 int value = ltc294x_read_charge_register(info, LTC294X_REG_ACC_CHARGE_MSB);
280 value -= LTC294X_MID_SUPPLY;
281 *val = convert_bin_to_uAh(info, value);
285 static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
291 ret = ltc294x_read_regs(info->client,
292 LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
293 value = (datar[0] << 8) | datar[1];
301 value *= 70800 / 5*4;
315 static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
321 ret = ltc294x_read_regs(info->client,
322 LTC2943_REG_CURRENT_MSB, &datar[0], 2);
323 value = (datar[0] << 8) | datar[1];
325 if (info->id == LTC2944_ID)
329 /* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
330 * the formula below keeps everything in s32 range while preserving
332 *val = 1000 * (value / (info->r_sense * 0x7FFF)); /* in uA */
336 static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
338 enum ltc294x_reg reg;
343 if (info->id == LTC2942_ID) {
344 reg = LTC2942_REG_TEMPERATURE_MSB;
345 value = 6000; /* Full-scale is 600 Kelvin */
347 reg = LTC2943_REG_TEMPERATURE_MSB;
348 value = 5100; /* Full-scale is 510 Kelvin */
350 ret = ltc294x_read_regs(info->client, reg, &datar[0], 2);
351 value *= (datar[0] << 8) | datar[1];
352 /* Convert to tenths of degree Celsius */
353 *val = value / 0xFFFF - 2722;
357 static int ltc294x_get_property(struct power_supply *psy,
358 enum power_supply_property prop,
359 union power_supply_propval *val)
361 struct ltc294x_info *info = power_supply_get_drvdata(psy);
364 case POWER_SUPPLY_PROP_CHARGE_FULL:
365 return ltc294x_get_charge(info, LTC294X_REG_CHARGE_THR_HIGH_MSB,
367 case POWER_SUPPLY_PROP_CHARGE_EMPTY:
368 return ltc294x_get_charge(info, LTC294X_REG_CHARGE_THR_LOW_MSB,
370 case POWER_SUPPLY_PROP_CHARGE_NOW:
371 return ltc294x_get_charge(info, LTC294X_REG_ACC_CHARGE_MSB,
373 case POWER_SUPPLY_PROP_CHARGE_COUNTER:
374 return ltc294x_get_charge_counter(info, &val->intval);
375 case POWER_SUPPLY_PROP_VOLTAGE_NOW:
376 return ltc294x_get_voltage(info, &val->intval);
377 case POWER_SUPPLY_PROP_CURRENT_NOW:
378 return ltc294x_get_current(info, &val->intval);
379 case POWER_SUPPLY_PROP_TEMP:
380 return ltc294x_get_temperature(info, &val->intval);
386 static int ltc294x_set_property(struct power_supply *psy,
387 enum power_supply_property psp,
388 const union power_supply_propval *val)
390 struct ltc294x_info *info = power_supply_get_drvdata(psy);
393 case POWER_SUPPLY_PROP_CHARGE_FULL:
394 return ltc294x_set_charge_thr(info,
395 LTC294X_REG_CHARGE_THR_HIGH_MSB, val->intval);
396 case POWER_SUPPLY_PROP_CHARGE_EMPTY:
397 return ltc294x_set_charge_thr(info,
398 LTC294X_REG_CHARGE_THR_LOW_MSB, val->intval);
399 case POWER_SUPPLY_PROP_CHARGE_NOW:
400 return ltc294x_set_charge_now(info, val->intval);
406 static int ltc294x_property_is_writeable(
407 struct power_supply *psy, enum power_supply_property psp)
410 case POWER_SUPPLY_PROP_CHARGE_FULL:
411 case POWER_SUPPLY_PROP_CHARGE_EMPTY:
412 case POWER_SUPPLY_PROP_CHARGE_NOW:
419 static void ltc294x_update(struct ltc294x_info *info)
421 int charge = ltc294x_read_charge_register(info, LTC294X_REG_ACC_CHARGE_MSB);
423 if (charge != info->charge) {
424 info->charge = charge;
425 power_supply_changed(info->supply);
429 static void ltc294x_work(struct work_struct *work)
431 struct ltc294x_info *info;
433 info = container_of(work, struct ltc294x_info, work.work);
434 ltc294x_update(info);
435 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
438 static enum power_supply_property ltc294x_properties[] = {
439 POWER_SUPPLY_PROP_CHARGE_COUNTER,
440 POWER_SUPPLY_PROP_CHARGE_FULL,
441 POWER_SUPPLY_PROP_CHARGE_EMPTY,
442 POWER_SUPPLY_PROP_CHARGE_NOW,
443 POWER_SUPPLY_PROP_VOLTAGE_NOW,
444 POWER_SUPPLY_PROP_TEMP,
445 POWER_SUPPLY_PROP_CURRENT_NOW,
448 static int ltc294x_i2c_remove(struct i2c_client *client)
450 struct ltc294x_info *info = i2c_get_clientdata(client);
452 cancel_delayed_work_sync(&info->work);
453 power_supply_unregister(info->supply);
457 static int ltc294x_i2c_probe(struct i2c_client *client,
458 const struct i2c_device_id *id)
460 struct power_supply_config psy_cfg = {};
461 struct ltc294x_info *info;
462 struct device_node *np;
468 info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
472 i2c_set_clientdata(client, info);
474 np = of_node_get(client->dev.of_node);
476 info->id = (enum ltc294x_id) (uintptr_t) of_device_get_match_data(
478 info->supply_desc.name = np->name;
480 /* r_sense can be negative, when sense+ is connected to the battery
481 * instead of the sense-. This results in reversed measurements. */
482 ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
484 dev_err(&client->dev,
485 "Could not find lltc,resistor-sense in devicetree\n");
488 info->r_sense = r_sense;
490 ret = of_property_read_u32(np, "lltc,prescaler-exponent",
493 dev_warn(&client->dev,
494 "lltc,prescaler-exponent not in devicetree\n");
495 prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
498 if (info->id == LTC2943_ID) {
499 if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
500 prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
501 info->Qlsb = ((340 * 50000) / r_sense) /
502 (4096 / (1 << (2*prescaler_exp)));
504 if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
505 prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
506 info->Qlsb = ((85 * 50000) / r_sense) /
507 (128 / (1 << prescaler_exp));
510 /* Read status register to check for LTC2942 */
511 if (info->id == LTC2941_ID || info->id == LTC2942_ID) {
512 ret = ltc294x_read_regs(client, LTC294X_REG_STATUS, &status, 1);
514 dev_err(&client->dev,
515 "Could not read status register\n");
518 if (status & LTC2941_REG_STATUS_CHIP_ID)
519 info->id = LTC2941_ID;
521 info->id = LTC2942_ID;
524 info->client = client;
525 info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
526 info->supply_desc.properties = ltc294x_properties;
530 info->supply_desc.num_properties =
531 ARRAY_SIZE(ltc294x_properties);
534 info->supply_desc.num_properties =
535 ARRAY_SIZE(ltc294x_properties) - 1;
539 info->supply_desc.num_properties =
540 ARRAY_SIZE(ltc294x_properties) - 3;
543 info->supply_desc.get_property = ltc294x_get_property;
544 info->supply_desc.set_property = ltc294x_set_property;
545 info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
546 info->supply_desc.external_power_changed = NULL;
548 psy_cfg.drv_data = info;
550 INIT_DELAYED_WORK(&info->work, ltc294x_work);
552 ret = ltc294x_reset(info, prescaler_exp);
554 dev_err(&client->dev, "Communication with chip failed\n");
558 info->supply = power_supply_register(&client->dev, &info->supply_desc,
560 if (IS_ERR(info->supply)) {
561 dev_err(&client->dev, "failed to register ltc2941\n");
562 return PTR_ERR(info->supply);
564 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
570 static void ltc294x_i2c_shutdown(struct i2c_client *client)
572 struct ltc294x_info *info = i2c_get_clientdata(client);
577 /* The LTC2941 does not need any special handling */
578 if (info->id == LTC2941_ID)
581 /* Read control register */
582 ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
586 /* Disable continuous ADC conversion as this drains the battery */
587 control = LTC294X_REG_CONTROL_ADC_DISABLE(value);
588 if (control != value)
589 ltc294x_write_regs(info->client, LTC294X_REG_CONTROL,
593 #ifdef CONFIG_PM_SLEEP
595 static int ltc294x_suspend(struct device *dev)
597 struct i2c_client *client = to_i2c_client(dev);
598 struct ltc294x_info *info = i2c_get_clientdata(client);
600 cancel_delayed_work(&info->work);
604 static int ltc294x_resume(struct device *dev)
606 struct i2c_client *client = to_i2c_client(dev);
607 struct ltc294x_info *info = i2c_get_clientdata(client);
609 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
613 static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
614 #define LTC294X_PM_OPS (<c294x_pm_ops)
617 #define LTC294X_PM_OPS NULL
618 #endif /* CONFIG_PM_SLEEP */
621 static const struct i2c_device_id ltc294x_i2c_id[] = {
622 { "ltc2941", LTC2941_ID, },
623 { "ltc2942", LTC2942_ID, },
624 { "ltc2943", LTC2943_ID, },
625 { "ltc2944", LTC2944_ID, },
628 MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);
630 static const struct of_device_id ltc294x_i2c_of_match[] = {
632 .compatible = "lltc,ltc2941",
633 .data = (void *)LTC2941_ID,
636 .compatible = "lltc,ltc2942",
637 .data = (void *)LTC2942_ID,
640 .compatible = "lltc,ltc2943",
641 .data = (void *)LTC2943_ID,
644 .compatible = "lltc,ltc2944",
645 .data = (void *)LTC2944_ID,
649 MODULE_DEVICE_TABLE(of, ltc294x_i2c_of_match);
651 static struct i2c_driver ltc294x_driver = {
654 .of_match_table = ltc294x_i2c_of_match,
655 .pm = LTC294X_PM_OPS,
657 .probe = ltc294x_i2c_probe,
658 .remove = ltc294x_i2c_remove,
659 .shutdown = ltc294x_i2c_shutdown,
660 .id_table = ltc294x_i2c_id,
662 module_i2c_driver(ltc294x_driver);
664 MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
665 MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
666 MODULE_DESCRIPTION("LTC2941/LTC2942/LTC2943/LTC2944 Battery Gas Gauge IC driver");
667 MODULE_LICENSE("GPL");