2 * I2C client/driver for the Linear Technology LTC2941 and LTC2943
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/types.h>
13 #include <linux/errno.h>
14 #include <linux/swab.h>
15 #include <linux/i2c.h>
16 #include <linux/delay.h>
17 #include <linux/idr.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_THRESH_HIGH_MSB = 0x04,
38 LTC294X_REG_THRESH_HIGH_LSB = 0x05,
39 LTC294X_REG_THRESH_LOW_MSB = 0x06,
40 LTC294X_REG_THRESH_LOW_LSB = 0x07,
41 LTC294X_REG_VOLTAGE_MSB = 0x08,
42 LTC294X_REG_VOLTAGE_LSB = 0x09,
43 LTC294X_REG_CURRENT_MSB = 0x0E,
44 LTC294X_REG_CURRENT_LSB = 0x0F,
45 LTC294X_REG_TEMPERATURE_MSB = 0x14,
46 LTC294X_REG_TEMPERATURE_LSB = 0x15,
49 #define LTC2943_REG_CONTROL_MODE_MASK (BIT(7) | BIT(6))
50 #define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
51 #define LTC294X_REG_CONTROL_PRESCALER_MASK (BIT(5) | BIT(4) | BIT(3))
52 #define LTC294X_REG_CONTROL_SHUTDOWN_MASK (BIT(0))
53 #define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
54 ((x << 3) & LTC294X_REG_CONTROL_PRESCALER_MASK)
55 #define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED 0
57 #define LTC2941_NUM_REGS 0x08
58 #define LTC2943_NUM_REGS 0x18
61 struct i2c_client *client; /* I2C Client pointer */
62 struct power_supply supply; /* Supply pointer */
63 struct delayed_work work; /* Work scheduler */
64 int num_regs; /* Number of registers (chip type) */
65 int id; /* Identifier of ltc294x chip */
66 int charge; /* Last charge register content */
67 int r_sense; /* mOhm */
71 static DEFINE_IDR(ltc294x_id);
72 static DEFINE_MUTEX(ltc294x_lock);
74 static inline int convert_bin_to_uAh(
75 const struct ltc294x_info *info, int Q)
77 return ((Q * (info->Qlsb / 10))) / 100;
80 static inline int convert_uAh_to_bin(
81 const struct ltc294x_info *info, int uAh)
85 Q = (uAh * 100) / (info->Qlsb/10);
86 return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
89 static int ltc294x_read_regs(struct i2c_client *client,
90 enum ltc294x_reg reg, u8 *buf, int num_regs)
93 struct i2c_msg msgs[2] = { };
96 msgs[0].addr = client->addr;
98 msgs[0].buf = ®_start;
100 msgs[1].addr = client->addr;
101 msgs[1].len = num_regs;
103 msgs[1].flags = I2C_M_RD;
105 ret = i2c_transfer(client->adapter, &msgs[0], 2);
107 dev_err(&client->dev, "ltc2941 read_reg failed!\n");
111 dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
112 __func__, reg, num_regs, *buf);
117 static int ltc294x_write_regs(struct i2c_client *client,
118 enum ltc294x_reg reg, const u8 *buf, int num_regs)
123 ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
125 dev_err(&client->dev, "ltc2941 write_reg failed!\n");
129 dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
130 __func__, reg, num_regs, *buf);
135 static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
141 /* Read status and control registers */
142 ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
144 dev_err(&info->client->dev,
145 "Could not read registers from device\n");
149 control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
150 LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
151 /* Put the 2943 into "monitor" mode, so it measures every 10 sec */
152 if (info->num_regs == LTC2943_NUM_REGS)
153 control |= LTC2943_REG_CONTROL_MODE_SCAN;
155 if (value != control) {
156 ret = ltc294x_write_regs(info->client,
157 LTC294X_REG_CONTROL, &control, 1);
159 dev_err(&info->client->dev,
160 "Could not write register\n");
171 static int ltc294x_read_charge_register(const struct ltc294x_info *info)
176 ret = ltc294x_read_regs(info->client,
177 LTC294X_REG_ACC_CHARGE_MSB, &datar[0], 2);
180 return (datar[0] << 8) + datar[1];
183 static int ltc294x_get_charge_now(const struct ltc294x_info *info, int *val)
185 int value = ltc294x_read_charge_register(info);
189 /* When r_sense < 0, this counts up when the battery discharges */
192 *val = convert_bin_to_uAh(info, value);
196 static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
203 value = convert_uAh_to_bin(info, val);
204 /* Direction depends on how sense+/- were connected */
207 if ((value < 0) || (value > 0xFFFF)) /* input validation */
210 /* Read control register */
211 ret = ltc294x_read_regs(info->client,
212 LTC294X_REG_CONTROL, &ctrl_reg, 1);
215 /* Disable analog section */
216 ctrl_reg |= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
217 ret = ltc294x_write_regs(info->client,
218 LTC294X_REG_CONTROL, &ctrl_reg, 1);
221 /* Set new charge value */
222 dataw[0] = I16_MSB(value);
223 dataw[1] = I16_LSB(value);
224 ret = ltc294x_write_regs(info->client,
225 LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
228 /* Enable analog section */
230 ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
231 ret = ltc294x_write_regs(info->client,
232 LTC294X_REG_CONTROL, &ctrl_reg, 1);
234 return ret < 0 ? ret : 0;
237 static int ltc294x_get_charge_counter(
238 const struct ltc294x_info *info, int *val)
240 int value = ltc294x_read_charge_register(info);
244 value -= LTC294X_MID_SUPPLY;
245 *val = convert_bin_to_uAh(info, value);
249 static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
255 ret = ltc294x_read_regs(info->client,
256 LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
257 value = (datar[0] << 8) | datar[1];
258 *val = ((value * 23600) / 0xFFFF) * 1000; /* in uV */
262 static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
268 ret = ltc294x_read_regs(info->client,
269 LTC294X_REG_CURRENT_MSB, &datar[0], 2);
270 value = (datar[0] << 8) | datar[1];
272 /* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
273 * the formula below keeps everything in s32 range while preserving
275 *val = 1000 * ((60000 * value) / (info->r_sense * 0x7FFF)); /* in uA */
279 static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
285 ret = ltc294x_read_regs(info->client,
286 LTC294X_REG_TEMPERATURE_MSB, &datar[0], 2);
287 value = (datar[0] << 8) | datar[1];
288 /* Full-scale is 510 Kelvin, convert to centidegrees */
289 *val = (((51000 * value) / 0xFFFF) - 27215);
293 static int ltc294x_get_property(struct power_supply *psy,
294 enum power_supply_property prop,
295 union power_supply_propval *val)
297 struct ltc294x_info *info =
298 container_of(psy, struct ltc294x_info, supply);
301 case POWER_SUPPLY_PROP_CHARGE_NOW:
302 return ltc294x_get_charge_now(info, &val->intval);
303 case POWER_SUPPLY_PROP_CHARGE_COUNTER:
304 return ltc294x_get_charge_counter(info, &val->intval);
305 case POWER_SUPPLY_PROP_VOLTAGE_NOW:
306 return ltc294x_get_voltage(info, &val->intval);
307 case POWER_SUPPLY_PROP_CURRENT_NOW:
308 return ltc294x_get_current(info, &val->intval);
309 case POWER_SUPPLY_PROP_TEMP:
310 return ltc294x_get_temperature(info, &val->intval);
316 static int ltc294x_set_property(struct power_supply *psy,
317 enum power_supply_property psp,
318 const union power_supply_propval *val)
320 struct ltc294x_info *info =
321 container_of(psy, struct ltc294x_info, supply);
324 case POWER_SUPPLY_PROP_CHARGE_NOW:
325 return ltc294x_set_charge_now(info, val->intval);
331 static int ltc294x_property_is_writeable(
332 struct power_supply *psy, enum power_supply_property psp)
335 case POWER_SUPPLY_PROP_CHARGE_NOW:
342 static void ltc294x_update(struct ltc294x_info *info)
344 int charge = ltc294x_read_charge_register(info);
346 if (charge != info->charge) {
347 info->charge = charge;
348 power_supply_changed(&info->supply);
352 static void ltc294x_work(struct work_struct *work)
354 struct ltc294x_info *info;
356 info = container_of(work, struct ltc294x_info, work.work);
357 ltc294x_update(info);
358 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
361 static enum power_supply_property ltc294x_properties[] = {
362 POWER_SUPPLY_PROP_CHARGE_COUNTER,
363 POWER_SUPPLY_PROP_CHARGE_NOW,
364 POWER_SUPPLY_PROP_VOLTAGE_NOW,
365 POWER_SUPPLY_PROP_CURRENT_NOW,
366 POWER_SUPPLY_PROP_TEMP,
369 static int ltc294x_i2c_remove(struct i2c_client *client)
371 struct ltc294x_info *info = i2c_get_clientdata(client);
373 cancel_delayed_work(&info->work);
374 power_supply_unregister(&info->supply);
375 kfree(info->supply.name);
376 mutex_lock(<c294x_lock);
377 idr_remove(<c294x_id, info->id);
378 mutex_unlock(<c294x_lock);
382 static int ltc294x_i2c_probe(struct i2c_client *client,
383 const struct i2c_device_id *id)
385 struct ltc294x_info *info;
390 struct device_node *np;
392 mutex_lock(<c294x_lock);
393 ret = idr_alloc(<c294x_id, client, 0, 0, GFP_KERNEL);
394 mutex_unlock(<c294x_lock);
400 info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
406 i2c_set_clientdata(client, info);
408 info->num_regs = id->driver_data;
409 info->supply.name = kasprintf(GFP_KERNEL, "%s-%d", client->name, num);
410 if (!info->supply.name) {
415 np = of_node_get(client->dev.of_node);
417 /* r_sense can be negative, when sense+ is connected to the battery
418 * instead of the sense-. This results in reversed measurements. */
419 ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
421 dev_err(&client->dev,
422 "Could not find lltc,resistor-sense in devicetree\n");
425 info->r_sense = r_sense;
427 ret = of_property_read_u32(np, "lltc,prescaler-exponent",
430 dev_warn(&client->dev,
431 "lltc,prescaler-exponent not in devicetree\n");
432 prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
435 if (info->num_regs == LTC2943_NUM_REGS) {
436 if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
437 prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
438 info->Qlsb = ((340 * 50000) / r_sense) /
439 (4096 / (1 << (2*prescaler_exp)));
441 if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
442 prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
443 info->Qlsb = ((58 * 50000) / r_sense) /
444 (128 / (1 << prescaler_exp));
447 info->client = client;
449 info->supply.type = POWER_SUPPLY_TYPE_BATTERY;
450 info->supply.properties = ltc294x_properties;
451 if (info->num_regs >= LTC294X_REG_TEMPERATURE_LSB)
452 info->supply.num_properties =
453 ARRAY_SIZE(ltc294x_properties);
454 else if (info->num_regs >= LTC294X_REG_CURRENT_LSB)
455 info->supply.num_properties =
456 ARRAY_SIZE(ltc294x_properties) - 1;
457 else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
458 info->supply.num_properties =
459 ARRAY_SIZE(ltc294x_properties) - 2;
461 info->supply.num_properties =
462 ARRAY_SIZE(ltc294x_properties) - 3;
463 info->supply.get_property = ltc294x_get_property;
464 info->supply.set_property = ltc294x_set_property;
465 info->supply.property_is_writeable = ltc294x_property_is_writeable;
466 info->supply.external_power_changed = NULL;
468 INIT_DELAYED_WORK(&info->work, ltc294x_work);
470 ret = ltc294x_reset(info, prescaler_exp);
472 dev_err(&client->dev, "Communication with chip failed\n");
476 ret = power_supply_register(&client->dev, &info->supply);
478 dev_err(&client->dev, "failed to register ltc2941\n");
481 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
487 kfree(info->supply.name);
491 mutex_lock(<c294x_lock);
492 idr_remove(<c294x_id, num);
493 mutex_unlock(<c294x_lock);
498 #ifdef CONFIG_PM_SLEEP
500 static int ltc294x_suspend(struct device *dev)
502 struct i2c_client *client = to_i2c_client(dev);
503 struct ltc294x_info *info = i2c_get_clientdata(client);
505 cancel_delayed_work(&info->work);
509 static int ltc294x_resume(struct device *dev)
511 struct i2c_client *client = to_i2c_client(dev);
512 struct ltc294x_info *info = i2c_get_clientdata(client);
514 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
518 static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
519 #define LTC294X_PM_OPS (<c294x_pm_ops)
522 #define LTC294X_PM_OPS NULL
523 #endif /* CONFIG_PM_SLEEP */
526 static const struct i2c_device_id ltc294x_i2c_id[] = {
527 {"ltc2941", LTC2941_NUM_REGS},
528 {"ltc2943", LTC2943_NUM_REGS},
531 MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);
533 static struct i2c_driver ltc294x_driver = {
536 .pm = LTC294X_PM_OPS,
538 .probe = ltc294x_i2c_probe,
539 .remove = ltc294x_i2c_remove,
540 .id_table = ltc294x_i2c_id,
542 module_i2c_driver(ltc294x_driver);
544 MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
545 MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
546 MODULE_DESCRIPTION("LTC2941/LTC2943 Battery Gas Gauge IC driver");
547 MODULE_LICENSE("GPL");