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/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>
23 #define I16_MSB(x) ((x >> 8) & 0xFF)
24 #define I16_LSB(x) (x & 0xFF)
26 #define LTC294X_WORK_DELAY 10 /* Update delay in seconds */
28 #define LTC294X_MAX_VALUE 0xFFFF
29 #define LTC294X_MID_SUPPLY 0x7FFF
31 #define LTC2941_MAX_PRESCALER_EXP 7
32 #define LTC2943_MAX_PRESCALER_EXP 6
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,
60 #define LTC2941_REG_STATUS_CHIP_ID BIT(7)
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)))
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 */
82 static inline int convert_bin_to_uAh(
83 const struct ltc294x_info *info, int Q)
85 return ((Q * (info->Qlsb / 10))) / 100;
88 static inline int convert_uAh_to_bin(
89 const struct ltc294x_info *info, int uAh)
93 Q = (uAh * 100) / (info->Qlsb/10);
94 return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
97 static int ltc294x_read_regs(struct i2c_client *client,
98 enum ltc294x_reg reg, u8 *buf, int num_regs)
101 struct i2c_msg msgs[2] = { };
104 msgs[0].addr = client->addr;
106 msgs[0].buf = ®_start;
108 msgs[1].addr = client->addr;
109 msgs[1].len = num_regs;
111 msgs[1].flags = I2C_M_RD;
113 ret = i2c_transfer(client->adapter, &msgs[0], 2);
115 dev_err(&client->dev, "ltc2941 read_reg failed!\n");
119 dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
120 __func__, reg, num_regs, *buf);
125 static int ltc294x_write_regs(struct i2c_client *client,
126 enum ltc294x_reg reg, const u8 *buf, int num_regs)
131 ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
133 dev_err(&client->dev, "ltc2941 write_reg failed!\n");
137 dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
138 __func__, reg, num_regs, *buf);
143 static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
149 /* Read status and control registers */
150 ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
152 dev_err(&info->client->dev,
153 "Could not read registers from device\n");
157 control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
158 LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
159 /* Put device into "monitor" mode */
161 case LTC2942_ID: /* 2942 measures every 2 sec */
162 control |= LTC2942_REG_CONTROL_MODE_SCAN;
165 case LTC2944_ID: /* 2943 and 2944 measure every 10 sec */
166 control |= LTC2943_REG_CONTROL_MODE_SCAN;
172 if (value != control) {
173 ret = ltc294x_write_regs(info->client,
174 LTC294X_REG_CONTROL, &control, 1);
176 dev_err(&info->client->dev,
177 "Could not write register\n");
188 static int ltc294x_read_charge_register(const struct ltc294x_info *info,
189 enum ltc294x_reg reg)
194 ret = ltc294x_read_regs(info->client, reg, &datar[0], 2);
197 return (datar[0] << 8) + datar[1];
200 static int ltc294x_get_charge(const struct ltc294x_info *info,
201 enum ltc294x_reg reg, int *val)
203 int value = ltc294x_read_charge_register(info, reg);
207 /* When r_sense < 0, this counts up when the battery discharges */
210 *val = convert_bin_to_uAh(info, value);
214 static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
221 value = convert_uAh_to_bin(info, val);
222 /* Direction depends on how sense+/- were connected */
225 if ((value < 0) || (value > 0xFFFF)) /* input validation */
228 /* Read control register */
229 ret = ltc294x_read_regs(info->client,
230 LTC294X_REG_CONTROL, &ctrl_reg, 1);
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);
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);
246 /* Enable analog section */
248 ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
249 ret = ltc294x_write_regs(info->client,
250 LTC294X_REG_CONTROL, &ctrl_reg, 1);
252 return ret < 0 ? ret : 0;
255 static int ltc294x_set_charge_thr(const struct ltc294x_info *info,
256 enum ltc294x_reg reg, int val)
261 value = convert_uAh_to_bin(info, val);
262 /* Direction depends on how sense+/- were connected */
265 if ((value < 0) || (value > 0xFFFF)) /* input validation */
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);
274 static int ltc294x_get_charge_counter(
275 const struct ltc294x_info *info, int *val)
277 int value = ltc294x_read_charge_register(info, LTC294X_REG_ACC_CHARGE_MSB);
281 value -= LTC294X_MID_SUPPLY;
282 *val = convert_bin_to_uAh(info, value);
286 static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
292 ret = ltc294x_read_regs(info->client,
293 LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
294 value = (datar[0] << 8) | datar[1];
302 value *= 70800 / 5*4;
316 static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
322 ret = ltc294x_read_regs(info->client,
323 LTC2943_REG_CURRENT_MSB, &datar[0], 2);
324 value = (datar[0] << 8) | datar[1];
326 if (info->id == LTC2944_ID)
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
333 *val = 1000 * (value / (info->r_sense * 0x7FFF)); /* in uA */
337 static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
339 enum ltc294x_reg reg;
344 if (info->id == LTC2942_ID) {
345 reg = LTC2942_REG_TEMPERATURE_MSB;
346 value = 6000; /* Full-scale is 600 Kelvin */
348 reg = LTC2943_REG_TEMPERATURE_MSB;
349 value = 5100; /* Full-scale is 510 Kelvin */
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;
358 static int ltc294x_get_property(struct power_supply *psy,
359 enum power_supply_property prop,
360 union power_supply_propval *val)
362 struct ltc294x_info *info = power_supply_get_drvdata(psy);
365 case POWER_SUPPLY_PROP_CHARGE_FULL:
366 return ltc294x_get_charge(info, LTC294X_REG_CHARGE_THR_HIGH_MSB,
368 case POWER_SUPPLY_PROP_CHARGE_EMPTY:
369 return ltc294x_get_charge(info, LTC294X_REG_CHARGE_THR_LOW_MSB,
371 case POWER_SUPPLY_PROP_CHARGE_NOW:
372 return ltc294x_get_charge(info, LTC294X_REG_ACC_CHARGE_MSB,
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);
387 static int ltc294x_set_property(struct power_supply *psy,
388 enum power_supply_property psp,
389 const union power_supply_propval *val)
391 struct ltc294x_info *info = power_supply_get_drvdata(psy);
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);
407 static int ltc294x_property_is_writeable(
408 struct power_supply *psy, enum power_supply_property psp)
411 case POWER_SUPPLY_PROP_CHARGE_FULL:
412 case POWER_SUPPLY_PROP_CHARGE_EMPTY:
413 case POWER_SUPPLY_PROP_CHARGE_NOW:
420 static void ltc294x_update(struct ltc294x_info *info)
422 int charge = ltc294x_read_charge_register(info, LTC294X_REG_ACC_CHARGE_MSB);
424 if (charge != info->charge) {
425 info->charge = charge;
426 power_supply_changed(info->supply);
430 static void ltc294x_work(struct work_struct *work)
432 struct ltc294x_info *info;
434 info = container_of(work, struct ltc294x_info, work.work);
435 ltc294x_update(info);
436 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
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,
449 static int ltc294x_i2c_probe(struct i2c_client *client,
450 const struct i2c_device_id *id)
452 struct power_supply_config psy_cfg = {};
453 struct ltc294x_info *info;
454 struct device_node *np;
460 info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
464 i2c_set_clientdata(client, info);
466 np = of_node_get(client->dev.of_node);
468 info->id = (enum ltc294x_id) (uintptr_t) of_device_get_match_data(
470 info->supply_desc.name = np->name;
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);
476 dev_err(&client->dev,
477 "Could not find lltc,resistor-sense in devicetree\n");
480 info->r_sense = r_sense;
482 ret = of_property_read_u32(np, "lltc,prescaler-exponent",
485 dev_warn(&client->dev,
486 "lltc,prescaler-exponent not in devicetree\n");
487 prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
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)));
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));
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);
506 dev_err(&client->dev,
507 "Could not read status register\n");
510 if (status & LTC2941_REG_STATUS_CHIP_ID)
511 info->id = LTC2941_ID;
513 info->id = LTC2942_ID;
516 info->client = client;
517 info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
518 info->supply_desc.properties = ltc294x_properties;
522 info->supply_desc.num_properties =
523 ARRAY_SIZE(ltc294x_properties);
526 info->supply_desc.num_properties =
527 ARRAY_SIZE(ltc294x_properties) - 1;
531 info->supply_desc.num_properties =
532 ARRAY_SIZE(ltc294x_properties) - 3;
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;
540 psy_cfg.drv_data = info;
542 ret = devm_delayed_work_autocancel(&client->dev, &info->work,
547 ret = ltc294x_reset(info, prescaler_exp);
549 dev_err(&client->dev, "Communication with chip failed\n");
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);
559 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
565 static void ltc294x_i2c_shutdown(struct i2c_client *client)
567 struct ltc294x_info *info = i2c_get_clientdata(client);
572 /* The LTC2941 does not need any special handling */
573 if (info->id == LTC2941_ID)
576 /* Read control register */
577 ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
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,
588 #ifdef CONFIG_PM_SLEEP
590 static int ltc294x_suspend(struct device *dev)
592 struct i2c_client *client = to_i2c_client(dev);
593 struct ltc294x_info *info = i2c_get_clientdata(client);
595 cancel_delayed_work(&info->work);
599 static int ltc294x_resume(struct device *dev)
601 struct i2c_client *client = to_i2c_client(dev);
602 struct ltc294x_info *info = i2c_get_clientdata(client);
604 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
608 static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
609 #define LTC294X_PM_OPS (<c294x_pm_ops)
612 #define LTC294X_PM_OPS NULL
613 #endif /* CONFIG_PM_SLEEP */
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, },
623 MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);
625 static const struct of_device_id ltc294x_i2c_of_match[] = {
627 .compatible = "lltc,ltc2941",
628 .data = (void *)LTC2941_ID,
631 .compatible = "lltc,ltc2942",
632 .data = (void *)LTC2942_ID,
635 .compatible = "lltc,ltc2943",
636 .data = (void *)LTC2943_ID,
639 .compatible = "lltc,ltc2944",
640 .data = (void *)LTC2944_ID,
644 MODULE_DEVICE_TABLE(of, ltc294x_i2c_of_match);
646 static struct i2c_driver ltc294x_driver = {
649 .of_match_table = ltc294x_i2c_of_match,
650 .pm = LTC294X_PM_OPS,
652 .probe = ltc294x_i2c_probe,
653 .shutdown = ltc294x_i2c_shutdown,
654 .id_table = ltc294x_i2c_id,
656 module_i2c_driver(ltc294x_driver);
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");