ds2782_battery.c

  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
 45struct ds278x_info;
 46
 47struct 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
 55struct 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
 66static DEFINE_IDA(battery_id);
 67
 68static 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
 82static 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
 97static 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
115static 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
144static 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
160static 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
172static 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
184static 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
200static 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
213static 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
241static 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
276static 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
287static 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
297static 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
305static 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
316static 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
325static 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
335static SIMPLE_DEV_PM_OPS(ds278x_battery_pm_ops, ds278x_suspend, ds278x_resume);
336
337enum ds278x_num_id {
338	DS2782 = 0,
339	DS2786,
340};
341
342static 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
355static void ds278x_free_ida(void *data)
356{
357	int num = (uintptr_t)data;
358
359	ida_free(&battery_id, num);
360}
361
362static 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
425static const struct i2c_device_id ds278x_id[] = {
426	{"ds2782", DS2782},
427	{"ds2786", DS2786},
428	{},
429};
430MODULE_DEVICE_TABLE(i2c, ds278x_id);
431
432static 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};
440module_i2c_driver(ds278x_battery_driver);
441
442MODULE_AUTHOR("Ryan Mallon");
443MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauge IC driver");
444MODULE_LICENSE("GPL");