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
38 struct 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 
53 static enum power_supply_property sbsm_props[] = {
54 	POWER_SUPPLY_PROP_ONLINE,
55 	POWER_SUPPLY_PROP_CHARGE_TYPE,
56 };
57 
58 static 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 
76 static 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 
92 static 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 
135 static 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 
143 static 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  */
172 static 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 
193 static 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  */
209 static int sbsm_gpio_direction_input(struct gpio_chip *gc, unsigned int off)
210 {
211 	return 0;
212 }
213 
214 static 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 
237 static 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 
267 static 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 
303 static 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 
312 static void sbsm_del_mux_adapter(void *data)
313 {
314 	struct sbsm_data *sbsm = data;
315 	i2c_mux_del_adapters(sbsm->muxc);
316 }
317 
318 static 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 
391 static const struct i2c_device_id sbsm_ids[] = {
392 	{ "sbs-manager", 0 },
393 	{ "ltc1760",     0 },
394 	{ }
395 };
396 MODULE_DEVICE_TABLE(i2c, sbsm_ids);
397 
398 #ifdef CONFIG_OF
399 static const struct of_device_id sbsm_dt_ids[] = {
400 	{ .compatible = "sbs,sbs-manager" },
401 	{ .compatible = "lltc,ltc1760" },
402 	{ }
403 };
404 MODULE_DEVICE_TABLE(of, sbsm_dt_ids);
405 #endif
406 
407 static struct i2c_driver sbsm_driver = {
408 	.driver = {
409 		.name = "sbsm",
410 		.of_match_table = of_match_ptr(sbsm_dt_ids),
411 	},
412 	.probe_new	= sbsm_probe,
413 	.alert		= sbsm_alert,
414 	.id_table	= sbsm_ids
415 };
416 module_i2c_driver(sbsm_driver);
417 
418 MODULE_LICENSE("GPL");
419 MODULE_AUTHOR("Karl-Heinz Schneider <karl-heinz@schneider-inet.de>");
420 MODULE_DESCRIPTION("SBSM Smart Battery System Manager");
421