xref: /linux/drivers/power/supply/ds2782_battery.c (revision f28f4890454cc97c18d31ab4686957857cc862b5)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * I2C client/driver for the Maxim/Dallas DS2782 Stand-Alone Fuel Gauge IC
4  *
5  * Copyright (C) 2009 Bluewater Systems Ltd
6  *
7  * Author: Ryan Mallon
8  *
9  * DS2786 added by Yulia Vilensky <vilensky@compulab.co.il>
10  *
11  * UEvent sending added by Evgeny Romanov <romanov@neurosoft.ru>
12  */
13 
14 #include <linux/devm-helpers.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/types.h>
18 #include <linux/errno.h>
19 #include <linux/swab.h>
20 #include <linux/i2c.h>
21 #include <linux/delay.h>
22 #include <linux/idr.h>
23 #include <linux/power_supply.h>
24 #include <linux/slab.h>
25 #include <linux/ds2782_battery.h>
26 
27 #define DS2782_REG_RARC		0x06	/* Remaining active relative capacity */
28 
29 #define DS278x_REG_VOLT_MSB	0x0c
30 #define DS278x_REG_TEMP_MSB	0x0a
31 #define DS278x_REG_CURRENT_MSB	0x0e
32 
33 /* EEPROM Block */
34 #define DS2782_REG_RSNSP	0x69	/* Sense resistor value */
35 
36 /* Current unit measurement in uA for a 1 milli-ohm sense resistor */
37 #define DS2782_CURRENT_UNITS	1563
38 
39 #define DS2786_REG_RARC		0x02	/* Remaining active relative capacity */
40 
41 #define DS2786_CURRENT_UNITS	25
42 
43 #define DS278x_DELAY		1000
44 
45 struct ds278x_info;
46 
47 struct ds278x_battery_ops {
48 	int (*get_battery_current)(struct ds278x_info *info, int *current_uA);
49 	int (*get_battery_voltage)(struct ds278x_info *info, int *voltage_uV);
50 	int (*get_battery_capacity)(struct ds278x_info *info, int *capacity);
51 };
52 
53 #define to_ds278x_info(x) power_supply_get_drvdata(x)
54 
55 struct ds278x_info {
56 	struct i2c_client	*client;
57 	struct power_supply	*battery;
58 	struct power_supply_desc	battery_desc;
59 	const struct ds278x_battery_ops *ops;
60 	struct delayed_work	bat_work;
61 	int                     rsns;
62 	int			capacity;
63 	int			status;		/* State Of Charge */
64 };
65 
66 static DEFINE_IDA(battery_id);
67 
68 static inline int ds278x_read_reg(struct ds278x_info *info, int reg, u8 *val)
69 {
70 	int ret;
71 
72 	ret = i2c_smbus_read_byte_data(info->client, reg);
73 	if (ret < 0) {
74 		dev_err(&info->client->dev, "register read failed\n");
75 		return ret;
76 	}
77 
78 	*val = ret;
79 	return 0;
80 }
81 
82 static inline int ds278x_read_reg16(struct ds278x_info *info, int reg_msb,
83 				    s16 *val)
84 {
85 	int ret;
86 
87 	ret = i2c_smbus_read_word_data(info->client, reg_msb);
88 	if (ret < 0) {
89 		dev_err(&info->client->dev, "register read failed\n");
90 		return ret;
91 	}
92 
93 	*val = swab16(ret);
94 	return 0;
95 }
96 
97 static int ds278x_get_temp(struct ds278x_info *info, int *temp)
98 {
99 	s16 raw;
100 	int err;
101 
102 	/*
103 	 * Temperature is measured in units of 0.125 degrees celcius, the
104 	 * power_supply class measures temperature in tenths of degrees
105 	 * celsius. The temperature value is stored as a 10 bit number, plus
106 	 * sign in the upper bits of a 16 bit register.
107 	 */
108 	err = ds278x_read_reg16(info, DS278x_REG_TEMP_MSB, &raw);
109 	if (err)
110 		return err;
111 	*temp = ((raw / 32) * 125) / 100;
112 	return 0;
113 }
114 
115 static int ds2782_get_current(struct ds278x_info *info, int *current_uA)
116 {
117 	int sense_res;
118 	int err;
119 	u8 sense_res_raw;
120 	s16 raw;
121 
122 	/*
123 	 * The units of measurement for current are dependent on the value of
124 	 * the sense resistor.
125 	 */
126 	err = ds278x_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw);
127 	if (err)
128 		return err;
129 	if (sense_res_raw == 0) {
130 		dev_err(&info->client->dev, "sense resistor value is 0\n");
131 		return -ENXIO;
132 	}
133 	sense_res = 1000 / sense_res_raw;
134 
135 	dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n",
136 		sense_res);
137 	err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
138 	if (err)
139 		return err;
140 	*current_uA = raw * (DS2782_CURRENT_UNITS / sense_res);
141 	return 0;
142 }
143 
144 static int ds2782_get_voltage(struct ds278x_info *info, int *voltage_uV)
145 {
146 	s16 raw;
147 	int err;
148 
149 	/*
150 	 * Voltage is measured in units of 4.88mV. The voltage is stored as
151 	 * a 10-bit number plus sign, in the upper bits of a 16-bit register
152 	 */
153 	err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
154 	if (err)
155 		return err;
156 	*voltage_uV = (raw / 32) * 4800;
157 	return 0;
158 }
159 
160 static int ds2782_get_capacity(struct ds278x_info *info, int *capacity)
161 {
162 	int err;
163 	u8 raw;
164 
165 	err = ds278x_read_reg(info, DS2782_REG_RARC, &raw);
166 	if (err)
167 		return err;
168 	*capacity = raw;
169 	return 0;
170 }
171 
172 static int ds2786_get_current(struct ds278x_info *info, int *current_uA)
173 {
174 	int err;
175 	s16 raw;
176 
177 	err = ds278x_read_reg16(info, DS278x_REG_CURRENT_MSB, &raw);
178 	if (err)
179 		return err;
180 	*current_uA = (raw / 16) * (DS2786_CURRENT_UNITS / info->rsns);
181 	return 0;
182 }
183 
184 static int ds2786_get_voltage(struct ds278x_info *info, int *voltage_uV)
185 {
186 	s16 raw;
187 	int err;
188 
189 	/*
190 	 * Voltage is measured in units of 1.22mV. The voltage is stored as
191 	 * a 12-bit number plus sign, in the upper bits of a 16-bit register
192 	 */
193 	err = ds278x_read_reg16(info, DS278x_REG_VOLT_MSB, &raw);
194 	if (err)
195 		return err;
196 	*voltage_uV = (raw / 8) * 1220;
197 	return 0;
198 }
199 
200 static int ds2786_get_capacity(struct ds278x_info *info, int *capacity)
201 {
202 	int err;
203 	u8 raw;
204 
205 	err = ds278x_read_reg(info, DS2786_REG_RARC, &raw);
206 	if (err)
207 		return err;
208 	/* Relative capacity is displayed with resolution 0.5 % */
209 	*capacity = raw/2 ;
210 	return 0;
211 }
212 
213 static int ds278x_get_status(struct ds278x_info *info, int *status)
214 {
215 	int err;
216 	int current_uA;
217 	int capacity;
218 
219 	err = info->ops->get_battery_current(info, &current_uA);
220 	if (err)
221 		return err;
222 
223 	err = info->ops->get_battery_capacity(info, &capacity);
224 	if (err)
225 		return err;
226 
227 	info->capacity = capacity;
228 
229 	if (capacity == 100)
230 		*status = POWER_SUPPLY_STATUS_FULL;
231 	else if (current_uA == 0)
232 		*status = POWER_SUPPLY_STATUS_NOT_CHARGING;
233 	else if (current_uA < 0)
234 		*status = POWER_SUPPLY_STATUS_DISCHARGING;
235 	else
236 		*status = POWER_SUPPLY_STATUS_CHARGING;
237 
238 	return 0;
239 }
240 
241 static int ds278x_battery_get_property(struct power_supply *psy,
242 				       enum power_supply_property prop,
243 				       union power_supply_propval *val)
244 {
245 	struct ds278x_info *info = to_ds278x_info(psy);
246 	int ret;
247 
248 	switch (prop) {
249 	case POWER_SUPPLY_PROP_STATUS:
250 		ret = ds278x_get_status(info, &val->intval);
251 		break;
252 
253 	case POWER_SUPPLY_PROP_CAPACITY:
254 		ret = info->ops->get_battery_capacity(info, &val->intval);
255 		break;
256 
257 	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
258 		ret = info->ops->get_battery_voltage(info, &val->intval);
259 		break;
260 
261 	case POWER_SUPPLY_PROP_CURRENT_NOW:
262 		ret = info->ops->get_battery_current(info, &val->intval);
263 		break;
264 
265 	case POWER_SUPPLY_PROP_TEMP:
266 		ret = ds278x_get_temp(info, &val->intval);
267 		break;
268 
269 	default:
270 		ret = -EINVAL;
271 	}
272 
273 	return ret;
274 }
275 
276 static void ds278x_bat_update(struct ds278x_info *info)
277 {
278 	int old_status = info->status;
279 	int old_capacity = info->capacity;
280 
281 	ds278x_get_status(info, &info->status);
282 
283 	if ((old_status != info->status) || (old_capacity != info->capacity))
284 		power_supply_changed(info->battery);
285 }
286 
287 static void ds278x_bat_work(struct work_struct *work)
288 {
289 	struct ds278x_info *info;
290 
291 	info = container_of(work, struct ds278x_info, bat_work.work);
292 	ds278x_bat_update(info);
293 
294 	schedule_delayed_work(&info->bat_work, DS278x_DELAY);
295 }
296 
297 static enum power_supply_property ds278x_battery_props[] = {
298 	POWER_SUPPLY_PROP_STATUS,
299 	POWER_SUPPLY_PROP_CAPACITY,
300 	POWER_SUPPLY_PROP_VOLTAGE_NOW,
301 	POWER_SUPPLY_PROP_CURRENT_NOW,
302 	POWER_SUPPLY_PROP_TEMP,
303 };
304 
305 static void ds278x_power_supply_init(struct power_supply_desc *battery)
306 {
307 	battery->type			= POWER_SUPPLY_TYPE_BATTERY;
308 	battery->properties		= ds278x_battery_props;
309 	battery->num_properties		= ARRAY_SIZE(ds278x_battery_props);
310 	battery->get_property		= ds278x_battery_get_property;
311 	battery->external_power_changed	= NULL;
312 }
313 
314 #ifdef CONFIG_PM_SLEEP
315 
316 static int ds278x_suspend(struct device *dev)
317 {
318 	struct i2c_client *client = to_i2c_client(dev);
319 	struct ds278x_info *info = i2c_get_clientdata(client);
320 
321 	cancel_delayed_work(&info->bat_work);
322 	return 0;
323 }
324 
325 static int ds278x_resume(struct device *dev)
326 {
327 	struct i2c_client *client = to_i2c_client(dev);
328 	struct ds278x_info *info = i2c_get_clientdata(client);
329 
330 	schedule_delayed_work(&info->bat_work, DS278x_DELAY);
331 	return 0;
332 }
333 #endif /* CONFIG_PM_SLEEP */
334 
335 static SIMPLE_DEV_PM_OPS(ds278x_battery_pm_ops, ds278x_suspend, ds278x_resume);
336 
337 enum ds278x_num_id {
338 	DS2782 = 0,
339 	DS2786,
340 };
341 
342 static const struct ds278x_battery_ops ds278x_ops[] = {
343 	[DS2782] = {
344 		.get_battery_current  = ds2782_get_current,
345 		.get_battery_voltage  = ds2782_get_voltage,
346 		.get_battery_capacity = ds2782_get_capacity,
347 	},
348 	[DS2786] = {
349 		.get_battery_current  = ds2786_get_current,
350 		.get_battery_voltage  = ds2786_get_voltage,
351 		.get_battery_capacity = ds2786_get_capacity,
352 	}
353 };
354 
355 static void ds278x_free_ida(void *data)
356 {
357 	int num = (uintptr_t)data;
358 
359 	ida_free(&battery_id, num);
360 }
361 
362 static int ds278x_battery_probe(struct i2c_client *client)
363 {
364 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
365 	struct ds278x_platform_data *pdata = client->dev.platform_data;
366 	struct power_supply_config psy_cfg = {};
367 	struct ds278x_info *info;
368 	int ret;
369 	int num;
370 
371 	/*
372 	 * ds2786 should have the sense resistor value set
373 	 * in the platform data
374 	 */
375 	if (id->driver_data == DS2786 && !pdata) {
376 		dev_err(&client->dev, "missing platform data for ds2786\n");
377 		return -EINVAL;
378 	}
379 
380 	/* Get an ID for this battery */
381 	num = ida_alloc(&battery_id, GFP_KERNEL);
382 	if (num < 0)
383 		return num;
384 	ret = devm_add_action_or_reset(&client->dev, ds278x_free_ida, (void *)(uintptr_t)num);
385 	if (ret)
386 		return ret;
387 
388 	info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
389 	if (!info)
390 		return -ENOMEM;
391 
392 	info->battery_desc.name = devm_kasprintf(&client->dev, GFP_KERNEL,
393 						 "%s-%d", client->name, num);
394 	if (!info->battery_desc.name)
395 		return -ENOMEM;
396 
397 	if (id->driver_data == DS2786)
398 		info->rsns = pdata->rsns;
399 
400 	i2c_set_clientdata(client, info);
401 	info->client = client;
402 	info->ops  = &ds278x_ops[id->driver_data];
403 	ds278x_power_supply_init(&info->battery_desc);
404 	psy_cfg.drv_data = info;
405 
406 	info->capacity = 100;
407 	info->status = POWER_SUPPLY_STATUS_FULL;
408 
409 	info->battery = devm_power_supply_register(&client->dev,
410 						   &info->battery_desc,
411 						   &psy_cfg);
412 	if (IS_ERR(info->battery)) {
413 		dev_err(&client->dev, "failed to register battery\n");
414 		return PTR_ERR(info->battery);
415 	}
416 
417 	ret = devm_delayed_work_autocancel(&client->dev, &info->bat_work, ds278x_bat_work);
418 	if (ret)
419 		return ret;
420 	schedule_delayed_work(&info->bat_work, DS278x_DELAY);
421 
422 	return 0;
423 }
424 
425 static const struct i2c_device_id ds278x_id[] = {
426 	{"ds2782", DS2782},
427 	{"ds2786", DS2786},
428 	{},
429 };
430 MODULE_DEVICE_TABLE(i2c, ds278x_id);
431 
432 static struct i2c_driver ds278x_battery_driver = {
433 	.driver 	= {
434 		.name	= "ds2782-battery",
435 		.pm	= &ds278x_battery_pm_ops,
436 	},
437 	.probe		= ds278x_battery_probe,
438 	.id_table	= ds278x_id,
439 };
440 module_i2c_driver(ds278x_battery_driver);
441 
442 MODULE_AUTHOR("Ryan Mallon");
443 MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauge IC driver");
444 MODULE_LICENSE("GPL");
445