1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Driver for SBS compliant Smart Battery System Managers
4 *
5 * The device communicates via i2c at address 0x0a and multiplexes access to up
6 * to four smart batteries at address 0x0b.
7 *
8 * Via sysfs interface the online state and charge type are presented.
9 *
10 * Datasheet SBSM:    http://sbs-forum.org/specs/sbsm100b.pdf
11 * Datasheet LTC1760: http://cds.linear.com/docs/en/datasheet/1760fb.pdf
12 *
13 * Karl-Heinz Schneider <karl-heinz@schneider-inet.de>
14 */
15
16#include <linux/gpio/driver.h>
17#include <linux/module.h>
18#include <linux/i2c.h>
19#include <linux/i2c-mux.h>
20#include <linux/power_supply.h>
21#include <linux/property.h>
22
23#define SBSM_MAX_BATS  4
24#define SBSM_RETRY_CNT 3
25
26/* registers addresses */
27#define SBSM_CMD_BATSYSSTATE     0x01
28#define SBSM_CMD_BATSYSSTATECONT 0x02
29#define SBSM_CMD_BATSYSINFO      0x04
30#define SBSM_CMD_LTC             0x3c
31
32#define SBSM_MASK_BAT_SUPPORTED  GENMASK(3, 0)
33#define SBSM_MASK_CHARGE_BAT     GENMASK(7, 4)
34#define SBSM_BIT_AC_PRESENT      BIT(0)
35#define SBSM_BIT_TURBO           BIT(7)
36
37#define SBSM_SMB_BAT_OFFSET      11
38struct sbsm_data {
39	struct i2c_client *client;
40	struct i2c_mux_core *muxc;
41
42	struct power_supply *psy;
43
44	u8 cur_chan;          /* currently selected channel */
45	struct gpio_chip chip;
46	bool is_ltc1760;      /* special capabilities */
47
48	unsigned int supported_bats;
49	unsigned int last_state;
50	unsigned int last_state_cont;
51};
52
53static enum power_supply_property sbsm_props[] = {
54	POWER_SUPPLY_PROP_ONLINE,
55	POWER_SUPPLY_PROP_CHARGE_TYPE,
56};
57
58static int sbsm_read_word(struct i2c_client *client, u8 address)
59{
60	int reg, retries;
61
62	for (retries = SBSM_RETRY_CNT; retries > 0; retries--) {
63		reg = i2c_smbus_read_word_data(client, address);
64		if (reg >= 0)
65			break;
66	}
67
68	if (reg < 0) {
69		dev_err(&client->dev, "failed to read register 0x%02x\n",
70			address);
71	}
72
73	return reg;
74}
75
76static int sbsm_write_word(struct i2c_client *client, u8 address, u16 word)
77{
78	int ret, retries;
79
80	for (retries = SBSM_RETRY_CNT; retries > 0; retries--) {
81		ret = i2c_smbus_write_word_data(client, address, word);
82		if (ret >= 0)
83			break;
84	}
85	if (ret < 0)
86		dev_err(&client->dev, "failed to write to register 0x%02x\n",
87			address);
88
89	return ret;
90}
91
92static int sbsm_get_property(struct power_supply *psy,
93			     enum power_supply_property psp,
94			     union power_supply_propval *val)
95{
96	struct sbsm_data *data = power_supply_get_drvdata(psy);
97	int regval = 0;
98
99	switch (psp) {
100	case POWER_SUPPLY_PROP_ONLINE:
101		regval = sbsm_read_word(data->client, SBSM_CMD_BATSYSSTATECONT);
102		if (regval < 0)
103			return regval;
104		val->intval = !!(regval & SBSM_BIT_AC_PRESENT);
105		break;
106
107	case POWER_SUPPLY_PROP_CHARGE_TYPE:
108		regval = sbsm_read_word(data->client, SBSM_CMD_BATSYSSTATE);
109		if (regval < 0)
110			return regval;
111
112		if ((regval & SBSM_MASK_CHARGE_BAT) == 0) {
113			val->intval = POWER_SUPPLY_CHARGE_TYPE_NONE;
114			return 0;
115		}
116		val->intval = POWER_SUPPLY_CHARGE_TYPE_TRICKLE;
117
118		if (data->is_ltc1760) {
119			/* charge mode fast if turbo is active */
120			regval = sbsm_read_word(data->client, SBSM_CMD_LTC);
121			if (regval < 0)
122				return regval;
123			else if (regval & SBSM_BIT_TURBO)
124				val->intval = POWER_SUPPLY_CHARGE_TYPE_FAST;
125		}
126		break;
127
128	default:
129		return -EINVAL;
130	}
131
132	return 0;
133}
134
135static int sbsm_prop_is_writeable(struct power_supply *psy,
136				  enum power_supply_property psp)
137{
138	struct sbsm_data *data = power_supply_get_drvdata(psy);
139
140	return (psp == POWER_SUPPLY_PROP_CHARGE_TYPE) && data->is_ltc1760;
141}
142
143static int sbsm_set_property(struct power_supply *psy,
144			     enum power_supply_property psp,
145			     const union power_supply_propval *val)
146{
147	struct sbsm_data *data = power_supply_get_drvdata(psy);
148	int ret = -EINVAL;
149	u16 regval;
150
151	switch (psp) {
152	case POWER_SUPPLY_PROP_CHARGE_TYPE:
153		/* write 1 to TURBO if type fast is given */
154		if (!data->is_ltc1760)
155			break;
156		regval = val->intval ==
157			 POWER_SUPPLY_CHARGE_TYPE_FAST ? SBSM_BIT_TURBO : 0;
158		ret = sbsm_write_word(data->client, SBSM_CMD_LTC, regval);
159		break;
160
161	default:
162		break;
163	}
164
165	return ret;
166}
167
168/*
169 * Switch to battery
170 * Parameter chan is directly the content of SMB_BAT* nibble
171 */
172static int sbsm_select(struct i2c_mux_core *muxc, u32 chan)
173{
174	struct sbsm_data *data = i2c_mux_priv(muxc);
175	struct device *dev = &data->client->dev;
176	int ret = 0;
177	u16 reg;
178
179	if (data->cur_chan == chan)
180		return ret;
181
182	/* chan goes from 1 ... 4 */
183	reg = BIT(SBSM_SMB_BAT_OFFSET + chan);
184	ret = sbsm_write_word(data->client, SBSM_CMD_BATSYSSTATE, reg);
185	if (ret)
186		dev_err(dev, "Failed to select channel %i\n", chan);
187	else
188		data->cur_chan = chan;
189
190	return ret;
191}
192
193static int sbsm_gpio_get_value(struct gpio_chip *gc, unsigned int off)
194{
195	struct sbsm_data *data = gpiochip_get_data(gc);
196	int ret;
197
198	ret = sbsm_read_word(data->client, SBSM_CMD_BATSYSSTATE);
199	if (ret < 0)
200		return ret;
201
202	return ret & BIT(off);
203}
204
205/*
206 * This needs to be defined or the GPIO lib fails to register the pin.
207 * But the 'gpio' is always an input.
208 */
209static int sbsm_gpio_direction_input(struct gpio_chip *gc, unsigned int off)
210{
211	return 0;
212}
213
214static int sbsm_do_alert(struct device *dev, void *d)
215{
216	struct i2c_client *client = i2c_verify_client(dev);
217	struct i2c_driver *driver;
218
219	if (!client || client->addr != 0x0b)
220		return 0;
221
222	device_lock(dev);
223	if (client->dev.driver) {
224		driver = to_i2c_driver(client->dev.driver);
225		if (driver->alert)
226			driver->alert(client, I2C_PROTOCOL_SMBUS_ALERT, 0);
227		else
228			dev_warn(&client->dev, "no driver alert()!\n");
229	} else {
230		dev_dbg(&client->dev, "alert with no driver\n");
231	}
232	device_unlock(dev);
233
234	return -EBUSY;
235}
236
237static void sbsm_alert(struct i2c_client *client, enum i2c_alert_protocol prot,
238		       unsigned int d)
239{
240	struct sbsm_data *sbsm = i2c_get_clientdata(client);
241
242	int ret, i, irq_bat = 0, state = 0;
243
244	ret = sbsm_read_word(sbsm->client, SBSM_CMD_BATSYSSTATE);
245	if (ret >= 0) {
246		irq_bat = ret ^ sbsm->last_state;
247		sbsm->last_state = ret;
248		state = ret;
249	}
250
251	ret = sbsm_read_word(sbsm->client, SBSM_CMD_BATSYSSTATECONT);
252	if ((ret >= 0) &&
253	    ((ret ^ sbsm->last_state_cont) & SBSM_BIT_AC_PRESENT)) {
254		irq_bat |= sbsm->supported_bats & state;
255		power_supply_changed(sbsm->psy);
256	}
257	sbsm->last_state_cont = ret;
258
259	for (i = 0; i < SBSM_MAX_BATS; i++) {
260		if (irq_bat & BIT(i)) {
261			device_for_each_child(&sbsm->muxc->adapter[i]->dev,
262					      NULL, sbsm_do_alert);
263		}
264	}
265}
266
267static int sbsm_gpio_setup(struct sbsm_data *data)
268{
269	struct gpio_chip *gc = &data->chip;
270	struct i2c_client *client = data->client;
271	struct device *dev = &client->dev;
272	int ret;
273
274	if (!device_property_present(dev, "gpio-controller"))
275		return 0;
276
277	ret  = sbsm_read_word(client, SBSM_CMD_BATSYSSTATE);
278	if (ret < 0)
279		return ret;
280	data->last_state = ret;
281
282	ret  = sbsm_read_word(client, SBSM_CMD_BATSYSSTATECONT);
283	if (ret < 0)
284		return ret;
285	data->last_state_cont = ret;
286
287	gc->get = sbsm_gpio_get_value;
288	gc->direction_input  = sbsm_gpio_direction_input;
289	gc->can_sleep = true;
290	gc->base = -1;
291	gc->ngpio = SBSM_MAX_BATS;
292	gc->label = client->name;
293	gc->parent = dev;
294	gc->owner = THIS_MODULE;
295
296	ret = devm_gpiochip_add_data(dev, gc, data);
297	if (ret)
298		return dev_err_probe(dev, ret, "devm_gpiochip_add_data failed\n");
299
300	return ret;
301}
302
303static const struct power_supply_desc sbsm_default_psy_desc = {
304	.type = POWER_SUPPLY_TYPE_MAINS,
305	.properties = sbsm_props,
306	.num_properties = ARRAY_SIZE(sbsm_props),
307	.get_property = &sbsm_get_property,
308	.set_property = &sbsm_set_property,
309	.property_is_writeable = &sbsm_prop_is_writeable,
310};
311
312static void sbsm_del_mux_adapter(void *data)
313{
314	struct sbsm_data *sbsm = data;
315	i2c_mux_del_adapters(sbsm->muxc);
316}
317
318static int sbsm_probe(struct i2c_client *client)
319{
320	const struct i2c_device_id *id = i2c_client_get_device_id(client);
321	struct i2c_adapter *adapter = client->adapter;
322	struct sbsm_data *data;
323	struct device *dev = &client->dev;
324	struct power_supply_desc *psy_desc;
325	struct power_supply_config psy_cfg = {};
326	int ret = 0, i;
327
328	/* Device listens only at address 0x0a */
329	if (client->addr != 0x0a)
330		return -EINVAL;
331
332	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA))
333		return -EPFNOSUPPORT;
334
335	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
336	if (!data)
337		return -ENOMEM;
338
339	i2c_set_clientdata(client, data);
340
341	data->client = client;
342	data->is_ltc1760 = !!strstr(id->name, "ltc1760");
343
344	ret  = sbsm_read_word(client, SBSM_CMD_BATSYSINFO);
345	if (ret < 0)
346		return ret;
347	data->supported_bats = ret & SBSM_MASK_BAT_SUPPORTED;
348	data->muxc = i2c_mux_alloc(adapter, dev, SBSM_MAX_BATS, 0,
349				   I2C_MUX_LOCKED, &sbsm_select, NULL);
350	if (!data->muxc)
351		return dev_err_probe(dev, -ENOMEM, "failed to alloc i2c mux\n");
352	data->muxc->priv = data;
353
354	ret = devm_add_action_or_reset(dev, sbsm_del_mux_adapter, data);
355	if (ret)
356		return ret;
357
358	/* register muxed i2c channels. One for each supported battery */
359	for (i = 0; i < SBSM_MAX_BATS; ++i) {
360		if (data->supported_bats & BIT(i)) {
361			ret = i2c_mux_add_adapter(data->muxc, 0, i + 1, 0);
362			if (ret)
363				break;
364		}
365	}
366	if (ret)
367		return dev_err_probe(dev, ret, "failed to register i2c mux channel %d\n", i + 1);
368
369	psy_desc = devm_kmemdup(dev, &sbsm_default_psy_desc, sizeof(*psy_desc), GFP_KERNEL);
370	if (!psy_desc)
371		return -ENOMEM;
372
373	psy_desc->name = devm_kasprintf(dev, GFP_KERNEL, "sbsm-%s", dev_name(&client->dev));
374	if (!psy_desc->name)
375		return -ENOMEM;
376
377	ret = sbsm_gpio_setup(data);
378	if (ret < 0)
379		return ret;
380
381	psy_cfg.drv_data = data;
382	psy_cfg.of_node = dev->of_node;
383	data->psy = devm_power_supply_register(dev, psy_desc, &psy_cfg);
384	if (IS_ERR(data->psy))
385		return dev_err_probe(dev, PTR_ERR(data->psy),
386				     "failed to register power supply %s\n", psy_desc->name);
387
388	return 0;
389}
390
391static const struct i2c_device_id sbsm_ids[] = {
392	{ "sbs-manager", 0 },
393	{ "ltc1760",     0 },
394	{ }
395};
396MODULE_DEVICE_TABLE(i2c, sbsm_ids);
397
398#ifdef CONFIG_OF
399static const struct of_device_id sbsm_dt_ids[] = {
400	{ .compatible = "sbs,sbs-manager" },
401	{ .compatible = "lltc,ltc1760" },
402	{ }
403};
404MODULE_DEVICE_TABLE(of, sbsm_dt_ids);
405#endif
406
407static struct i2c_driver sbsm_driver = {
408	.driver = {
409		.name = "sbsm",
410		.of_match_table = of_match_ptr(sbsm_dt_ids),
411	},
412	.probe		= sbsm_probe,
413	.alert		= sbsm_alert,
414	.id_table	= sbsm_ids
415};
416module_i2c_driver(sbsm_driver);
417
418MODULE_LICENSE("GPL");
419MODULE_AUTHOR("Karl-Heinz Schneider <karl-heinz@schneider-inet.de>");
420MODULE_DESCRIPTION("SBSM Smart Battery System Manager");
421