Linux preempt-rt

Check our new training course

Real-Time Linux with PREEMPT_RT

Check our new training course
with Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for SBS compliant Smart Battery System Managers
 *
 * The device communicates via i2c at address 0x0a and multiplexes access to up
 * to four smart batteries at address 0x0b.
 *
 * Via sysfs interface the online state and charge type are presented.
 *
 * Datasheet SBSM:    http://sbs-forum.org/specs/sbsm100b.pdf
 * Datasheet LTC1760: http://cds.linear.com/docs/en/datasheet/1760fb.pdf
 *
 * Karl-Heinz Schneider <karl-heinz@schneider-inet.de>
 */

#include <linux/gpio.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/i2c-mux.h>
#include <linux/power_supply.h>
#include <linux/property.h>

#define SBSM_MAX_BATS  4
#define SBSM_RETRY_CNT 3

/* registers addresses */
#define SBSM_CMD_BATSYSSTATE     0x01
#define SBSM_CMD_BATSYSSTATECONT 0x02
#define SBSM_CMD_BATSYSINFO      0x04
#define SBSM_CMD_LTC             0x3c

#define SBSM_MASK_BAT_SUPPORTED  GENMASK(3, 0)
#define SBSM_MASK_CHARGE_BAT     GENMASK(7, 4)
#define SBSM_BIT_AC_PRESENT      BIT(0)
#define SBSM_BIT_TURBO           BIT(7)

#define SBSM_SMB_BAT_OFFSET      11
struct sbsm_data {
	struct i2c_client *client;
	struct i2c_mux_core *muxc;

	struct power_supply *psy;

	u8 cur_chan;          /* currently selected channel */
	struct gpio_chip chip;
	bool is_ltc1760;      /* special capabilities */

	unsigned int supported_bats;
	unsigned int last_state;
	unsigned int last_state_cont;
};

static enum power_supply_property sbsm_props[] = {
	POWER_SUPPLY_PROP_ONLINE,
	POWER_SUPPLY_PROP_CHARGE_TYPE,
};

static int sbsm_read_word(struct i2c_client *client, u8 address)
{
	int reg, retries;

	for (retries = SBSM_RETRY_CNT; retries > 0; retries--) {
		reg = i2c_smbus_read_word_data(client, address);
		if (reg >= 0)
			break;
	}

	if (reg < 0) {
		dev_err(&client->dev, "failed to read register 0x%02x\n",
			address);
	}

	return reg;
}

static int sbsm_write_word(struct i2c_client *client, u8 address, u16 word)
{
	int ret, retries;

	for (retries = SBSM_RETRY_CNT; retries > 0; retries--) {
		ret = i2c_smbus_write_word_data(client, address, word);
		if (ret >= 0)
			break;
	}
	if (ret < 0)
		dev_err(&client->dev, "failed to write to register 0x%02x\n",
			address);

	return ret;
}

static int sbsm_get_property(struct power_supply *psy,
			     enum power_supply_property psp,
			     union power_supply_propval *val)
{
	struct sbsm_data *data = power_supply_get_drvdata(psy);
	int regval = 0;

	switch (psp) {
	case POWER_SUPPLY_PROP_ONLINE:
		regval = sbsm_read_word(data->client, SBSM_CMD_BATSYSSTATECONT);
		if (regval < 0)
			return regval;
		val->intval = !!(regval & SBSM_BIT_AC_PRESENT);
		break;

	case POWER_SUPPLY_PROP_CHARGE_TYPE:
		regval = sbsm_read_word(data->client, SBSM_CMD_BATSYSSTATE);
		if (regval < 0)
			return regval;

		if ((regval & SBSM_MASK_CHARGE_BAT) == 0) {
			val->intval = POWER_SUPPLY_CHARGE_TYPE_NONE;
			return 0;
		}
		val->intval = POWER_SUPPLY_CHARGE_TYPE_TRICKLE;

		if (data->is_ltc1760) {
			/* charge mode fast if turbo is active */
			regval = sbsm_read_word(data->client, SBSM_CMD_LTC);
			if (regval < 0)
				return regval;
			else if (regval & SBSM_BIT_TURBO)
				val->intval = POWER_SUPPLY_CHARGE_TYPE_FAST;
		}
		break;

	default:
		return -EINVAL;
	}

	return 0;
}

static int sbsm_prop_is_writeable(struct power_supply *psy,
				  enum power_supply_property psp)
{
	struct sbsm_data *data = power_supply_get_drvdata(psy);

	return (psp == POWER_SUPPLY_PROP_CHARGE_TYPE) && data->is_ltc1760;
}

static int sbsm_set_property(struct power_supply *psy,
			     enum power_supply_property psp,
			     const union power_supply_propval *val)
{
	struct sbsm_data *data = power_supply_get_drvdata(psy);
	int ret = -EINVAL;
	u16 regval;

	switch (psp) {
	case POWER_SUPPLY_PROP_CHARGE_TYPE:
		/* write 1 to TURBO if type fast is given */
		if (!data->is_ltc1760)
			break;
		regval = val->intval ==
			 POWER_SUPPLY_CHARGE_TYPE_FAST ? SBSM_BIT_TURBO : 0;
		ret = sbsm_write_word(data->client, SBSM_CMD_LTC, regval);
		break;

	default:
		break;
	}

	return ret;
}

/*
 * Switch to battery
 * Parameter chan is directly the content of SMB_BAT* nibble
 */
static int sbsm_select(struct i2c_mux_core *muxc, u32 chan)
{
	struct sbsm_data *data = i2c_mux_priv(muxc);
	struct device *dev = &data->client->dev;
	int ret = 0;
	u16 reg;

	if (data->cur_chan == chan)
		return ret;

	/* chan goes from 1 ... 4 */
	reg = BIT(SBSM_SMB_BAT_OFFSET + chan);
	ret = sbsm_write_word(data->client, SBSM_CMD_BATSYSSTATE, reg);
	if (ret)
		dev_err(dev, "Failed to select channel %i\n", chan);
	else
		data->cur_chan = chan;

	return ret;
}

static int sbsm_gpio_get_value(struct gpio_chip *gc, unsigned int off)
{
	struct sbsm_data *data = gpiochip_get_data(gc);
	int ret;

	ret = sbsm_read_word(data->client, SBSM_CMD_BATSYSSTATE);
	if (ret < 0)
		return ret;

	return ret & BIT(off);
}

/*
 * This needs to be defined or the GPIO lib fails to register the pin.
 * But the 'gpio' is always an input.
 */
static int sbsm_gpio_direction_input(struct gpio_chip *gc, unsigned int off)
{
	return 0;
}

static int sbsm_do_alert(struct device *dev, void *d)
{
	struct i2c_client *client = i2c_verify_client(dev);
	struct i2c_driver *driver;

	if (!client || client->addr != 0x0b)
		return 0;

	device_lock(dev);
	if (client->dev.driver) {
		driver = to_i2c_driver(client->dev.driver);
		if (driver->alert)
			driver->alert(client, I2C_PROTOCOL_SMBUS_ALERT, 0);
		else
			dev_warn(&client->dev, "no driver alert()!\n");
	} else {
		dev_dbg(&client->dev, "alert with no driver\n");
	}
	device_unlock(dev);

	return -EBUSY;
}

static void sbsm_alert(struct i2c_client *client, enum i2c_alert_protocol prot,
		       unsigned int d)
{
	struct sbsm_data *sbsm = i2c_get_clientdata(client);

	int ret, i, irq_bat = 0, state = 0;

	ret = sbsm_read_word(sbsm->client, SBSM_CMD_BATSYSSTATE);
	if (ret >= 0) {
		irq_bat = ret ^ sbsm->last_state;
		sbsm->last_state = ret;
		state = ret;
	}

	ret = sbsm_read_word(sbsm->client, SBSM_CMD_BATSYSSTATECONT);
	if ((ret >= 0) &&
	    ((ret ^ sbsm->last_state_cont) & SBSM_BIT_AC_PRESENT)) {
		irq_bat |= sbsm->supported_bats & state;
		power_supply_changed(sbsm->psy);
	}
	sbsm->last_state_cont = ret;

	for (i = 0; i < SBSM_MAX_BATS; i++) {
		if (irq_bat & BIT(i)) {
			device_for_each_child(&sbsm->muxc->adapter[i]->dev,
					      NULL, sbsm_do_alert);
		}
	}
}

static int sbsm_gpio_setup(struct sbsm_data *data)
{
	struct gpio_chip *gc = &data->chip;
	struct i2c_client *client = data->client;
	struct device *dev = &client->dev;
	int ret;

	if (!device_property_present(dev, "gpio-controller"))
		return 0;

	ret  = sbsm_read_word(client, SBSM_CMD_BATSYSSTATE);
	if (ret < 0)
		return ret;
	data->last_state = ret;

	ret  = sbsm_read_word(client, SBSM_CMD_BATSYSSTATECONT);
	if (ret < 0)
		return ret;
	data->last_state_cont = ret;

	gc->get = sbsm_gpio_get_value;
	gc->direction_input  = sbsm_gpio_direction_input;
	gc->can_sleep = true;
	gc->base = -1;
	gc->ngpio = SBSM_MAX_BATS;
	gc->label = client->name;
	gc->parent = dev;
	gc->owner = THIS_MODULE;

	ret = devm_gpiochip_add_data(dev, gc, data);
	if (ret) {
		dev_err(dev, "devm_gpiochip_add_data failed: %d\n", ret);
		return ret;
	}

	return ret;
}

static const struct power_supply_desc sbsm_default_psy_desc = {
	.type = POWER_SUPPLY_TYPE_MAINS,
	.properties = sbsm_props,
	.num_properties = ARRAY_SIZE(sbsm_props),
	.get_property = &sbsm_get_property,
	.set_property = &sbsm_set_property,
	.property_is_writeable = &sbsm_prop_is_writeable,
};

static int sbsm_probe(struct i2c_client *client,
		      const struct i2c_device_id *id)
{
	struct i2c_adapter *adapter = client->adapter;
	struct sbsm_data *data;
	struct device *dev = &client->dev;
	struct power_supply_desc *psy_desc;
	struct power_supply_config psy_cfg = {};
	int ret = 0, i;

	/* Device listens only at address 0x0a */
	if (client->addr != 0x0a)
		return -EINVAL;

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA))
		return -EPFNOSUPPORT;

	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	i2c_set_clientdata(client, data);

	data->client = client;
	data->is_ltc1760 = !!strstr(id->name, "ltc1760");

	ret  = sbsm_read_word(client, SBSM_CMD_BATSYSINFO);
	if (ret < 0)
		return ret;
	data->supported_bats = ret & SBSM_MASK_BAT_SUPPORTED;
	data->muxc = i2c_mux_alloc(adapter, dev, SBSM_MAX_BATS, 0,
				   I2C_MUX_LOCKED, &sbsm_select, NULL);
	if (!data->muxc) {
		dev_err(dev, "failed to alloc i2c mux\n");
		ret = -ENOMEM;
		goto err_mux_alloc;
	}
	data->muxc->priv = data;

	/* register muxed i2c channels. One for each supported battery */
	for (i = 0; i < SBSM_MAX_BATS; ++i) {
		if (data->supported_bats & BIT(i)) {
			ret = i2c_mux_add_adapter(data->muxc, 0, i + 1, 0);
			if (ret)
				break;
		}
	}
	if (ret) {
		dev_err(dev, "failed to register i2c mux channel %d\n", i + 1);
		goto err_mux_register;
	}

	psy_desc = devm_kmemdup(dev, &sbsm_default_psy_desc,
				sizeof(struct power_supply_desc),
				GFP_KERNEL);
	if (!psy_desc) {
		ret = -ENOMEM;
		goto err_psy;
	}

	psy_desc->name = devm_kasprintf(dev, GFP_KERNEL, "sbsm-%s",
					dev_name(&client->dev));
	if (!psy_desc->name) {
		ret = -ENOMEM;
		goto err_psy;
	}
	ret = sbsm_gpio_setup(data);
	if (ret < 0)
		goto err_psy;

	psy_cfg.drv_data = data;
	psy_cfg.of_node = dev->of_node;
	data->psy = devm_power_supply_register(dev, psy_desc, &psy_cfg);
	if (IS_ERR(data->psy)) {
		ret = PTR_ERR(data->psy);
		dev_err(dev, "failed to register power supply %s\n",
			psy_desc->name);
		goto err_psy;
	}

	return 0;

err_psy:
err_mux_register:
	i2c_mux_del_adapters(data->muxc);

err_mux_alloc:
	return ret;
}

static int sbsm_remove(struct i2c_client *client)
{
	struct sbsm_data *data = i2c_get_clientdata(client);

	i2c_mux_del_adapters(data->muxc);
	return 0;
}

static const struct i2c_device_id sbsm_ids[] = {
	{ "sbs-manager", 0 },
	{ "ltc1760",     0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, sbsm_ids);

#ifdef CONFIG_OF
static const struct of_device_id sbsm_dt_ids[] = {
	{ .compatible = "sbs,sbs-manager" },
	{ .compatible = "lltc,ltc1760" },
	{ }
};
MODULE_DEVICE_TABLE(of, sbsm_dt_ids);
#endif

static struct i2c_driver sbsm_driver = {
	.driver = {
		.name = "sbsm",
		.of_match_table = of_match_ptr(sbsm_dt_ids),
	},
	.probe		= sbsm_probe,
	.remove		= sbsm_remove,
	.alert		= sbsm_alert,
	.id_table	= sbsm_ids
};
module_i2c_driver(sbsm_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Karl-Heinz Schneider <karl-heinz@schneider-inet.de>");
MODULE_DESCRIPTION("SBSM Smart Battery System Manager");