1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * TI LP855x Backlight Driver
4  *
5  *			Copyright (C) 2011 Texas Instruments
6  */
7 
8 #include <linux/acpi.h>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/i2c.h>
12 #include <linux/backlight.h>
13 #include <linux/delay.h>
14 #include <linux/err.h>
15 #include <linux/of.h>
16 #include <linux/platform_data/lp855x.h>
17 #include <linux/pwm.h>
18 #include <linux/regulator/consumer.h>
19 
20 /* LP8550/1/2/3/6 Registers */
21 #define LP855X_BRIGHTNESS_CTRL		0x00
22 #define LP855X_DEVICE_CTRL		0x01
23 #define LP855X_EEPROM_START		0xA0
24 #define LP855X_EEPROM_END		0xA7
25 #define LP8556_EPROM_START		0xA0
26 #define LP8556_EPROM_END		0xAF
27 
28 /* LP8555/7 Registers */
29 #define LP8557_BL_CMD			0x00
30 #define LP8557_BL_MASK			0x01
31 #define LP8557_BL_ON			0x01
32 #define LP8557_BL_OFF			0x00
33 #define LP8557_BRIGHTNESS_CTRL		0x04
34 #define LP8557_CONFIG			0x10
35 #define LP8555_EPROM_START		0x10
36 #define LP8555_EPROM_END		0x7A
37 #define LP8557_EPROM_START		0x10
38 #define LP8557_EPROM_END		0x1E
39 
40 #define DEFAULT_BL_NAME		"lcd-backlight"
41 #define MAX_BRIGHTNESS		255
42 
43 enum lp855x_brightness_ctrl_mode {
44 	PWM_BASED = 1,
45 	REGISTER_BASED,
46 };
47 
48 struct lp855x;
49 
50 /*
51  * struct lp855x_device_config
52  * @pre_init_device: init device function call before updating the brightness
53  * @reg_brightness: register address for brigthenss control
54  * @reg_devicectrl: register address for device control
55  * @post_init_device: late init device function call
56  */
57 struct lp855x_device_config {
58 	int (*pre_init_device)(struct lp855x *);
59 	u8 reg_brightness;
60 	u8 reg_devicectrl;
61 	int (*post_init_device)(struct lp855x *);
62 };
63 
64 struct lp855x {
65 	const char *chipname;
66 	enum lp855x_chip_id chip_id;
67 	enum lp855x_brightness_ctrl_mode mode;
68 	struct lp855x_device_config *cfg;
69 	struct i2c_client *client;
70 	struct backlight_device *bl;
71 	struct device *dev;
72 	struct lp855x_platform_data *pdata;
73 	struct pwm_device *pwm;
74 	bool needs_pwm_init;
75 	struct regulator *supply;	/* regulator for VDD input */
76 	struct regulator *enable;	/* regulator for EN/VDDIO input */
77 };
78 
lp855x_write_byte(struct lp855x * lp,u8 reg,u8 data)79 static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
80 {
81 	return i2c_smbus_write_byte_data(lp->client, reg, data);
82 }
83 
lp855x_update_bit(struct lp855x * lp,u8 reg,u8 mask,u8 data)84 static int lp855x_update_bit(struct lp855x *lp, u8 reg, u8 mask, u8 data)
85 {
86 	int ret;
87 	u8 tmp;
88 
89 	ret = i2c_smbus_read_byte_data(lp->client, reg);
90 	if (ret < 0) {
91 		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
92 		return ret;
93 	}
94 
95 	tmp = (u8)ret;
96 	tmp &= ~mask;
97 	tmp |= data & mask;
98 
99 	return lp855x_write_byte(lp, reg, tmp);
100 }
101 
lp855x_is_valid_rom_area(struct lp855x * lp,u8 addr)102 static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
103 {
104 	u8 start, end;
105 
106 	switch (lp->chip_id) {
107 	case LP8550:
108 	case LP8551:
109 	case LP8552:
110 	case LP8553:
111 		start = LP855X_EEPROM_START;
112 		end = LP855X_EEPROM_END;
113 		break;
114 	case LP8556:
115 		start = LP8556_EPROM_START;
116 		end = LP8556_EPROM_END;
117 		break;
118 	case LP8555:
119 		start = LP8555_EPROM_START;
120 		end = LP8555_EPROM_END;
121 		break;
122 	case LP8557:
123 		start = LP8557_EPROM_START;
124 		end = LP8557_EPROM_END;
125 		break;
126 	default:
127 		return false;
128 	}
129 
130 	return addr >= start && addr <= end;
131 }
132 
lp8557_bl_off(struct lp855x * lp)133 static int lp8557_bl_off(struct lp855x *lp)
134 {
135 	/* BL_ON = 0 before updating EPROM settings */
136 	return lp855x_update_bit(lp, LP8557_BL_CMD, LP8557_BL_MASK,
137 				LP8557_BL_OFF);
138 }
139 
lp8557_bl_on(struct lp855x * lp)140 static int lp8557_bl_on(struct lp855x *lp)
141 {
142 	/* BL_ON = 1 after updating EPROM settings */
143 	return lp855x_update_bit(lp, LP8557_BL_CMD, LP8557_BL_MASK,
144 				LP8557_BL_ON);
145 }
146 
147 static struct lp855x_device_config lp855x_dev_cfg = {
148 	.reg_brightness = LP855X_BRIGHTNESS_CTRL,
149 	.reg_devicectrl = LP855X_DEVICE_CTRL,
150 };
151 
152 static struct lp855x_device_config lp8557_dev_cfg = {
153 	.reg_brightness = LP8557_BRIGHTNESS_CTRL,
154 	.reg_devicectrl = LP8557_CONFIG,
155 	.pre_init_device = lp8557_bl_off,
156 	.post_init_device = lp8557_bl_on,
157 };
158 
159 /*
160  * Device specific configuration flow
161  *
162  *    a) pre_init_device(optional)
163  *    b) update the brightness register
164  *    c) update device control register
165  *    d) update ROM area(optional)
166  *    e) post_init_device(optional)
167  *
168  */
lp855x_configure(struct lp855x * lp)169 static int lp855x_configure(struct lp855x *lp)
170 {
171 	u8 val, addr;
172 	int i, ret;
173 	struct lp855x_platform_data *pd = lp->pdata;
174 
175 	if (lp->cfg->pre_init_device) {
176 		ret = lp->cfg->pre_init_device(lp);
177 		if (ret) {
178 			dev_err(lp->dev, "pre init device err: %d\n", ret);
179 			goto err;
180 		}
181 	}
182 
183 	val = pd->initial_brightness;
184 	ret = lp855x_write_byte(lp, lp->cfg->reg_brightness, val);
185 	if (ret)
186 		goto err;
187 
188 	val = pd->device_control;
189 	ret = lp855x_write_byte(lp, lp->cfg->reg_devicectrl, val);
190 	if (ret)
191 		goto err;
192 
193 	if (pd->size_program > 0) {
194 		for (i = 0; i < pd->size_program; i++) {
195 			addr = pd->rom_data[i].addr;
196 			val = pd->rom_data[i].val;
197 			if (!lp855x_is_valid_rom_area(lp, addr))
198 				continue;
199 
200 			ret = lp855x_write_byte(lp, addr, val);
201 			if (ret)
202 				goto err;
203 		}
204 	}
205 
206 	if (lp->cfg->post_init_device) {
207 		ret = lp->cfg->post_init_device(lp);
208 		if (ret) {
209 			dev_err(lp->dev, "post init device err: %d\n", ret);
210 			goto err;
211 		}
212 	}
213 
214 	return 0;
215 
216 err:
217 	return ret;
218 }
219 
lp855x_pwm_ctrl(struct lp855x * lp,int br,int max_br)220 static int lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
221 {
222 	struct pwm_state state;
223 
224 	if (lp->needs_pwm_init) {
225 		pwm_init_state(lp->pwm, &state);
226 		/* Legacy platform data compatibility */
227 		if (lp->pdata->period_ns > 0)
228 			state.period = lp->pdata->period_ns;
229 		lp->needs_pwm_init = false;
230 	} else {
231 		pwm_get_state(lp->pwm, &state);
232 	}
233 
234 	state.duty_cycle = div_u64(br * state.period, max_br);
235 	state.enabled = state.duty_cycle;
236 
237 	return pwm_apply_might_sleep(lp->pwm, &state);
238 }
239 
lp855x_bl_update_status(struct backlight_device * bl)240 static int lp855x_bl_update_status(struct backlight_device *bl)
241 {
242 	struct lp855x *lp = bl_get_data(bl);
243 	int brightness = bl->props.brightness;
244 
245 	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
246 		brightness = 0;
247 
248 	if (lp->mode == PWM_BASED)
249 		return lp855x_pwm_ctrl(lp, brightness,
250 				      bl->props.max_brightness);
251 	else if (lp->mode == REGISTER_BASED)
252 		return lp855x_write_byte(lp, lp->cfg->reg_brightness,
253 					(u8)brightness);
254 	return -EINVAL;
255 }
256 
257 static const struct backlight_ops lp855x_bl_ops = {
258 	.options = BL_CORE_SUSPENDRESUME,
259 	.update_status = lp855x_bl_update_status,
260 };
261 
lp855x_backlight_register(struct lp855x * lp)262 static int lp855x_backlight_register(struct lp855x *lp)
263 {
264 	struct backlight_device *bl;
265 	struct backlight_properties props;
266 	struct lp855x_platform_data *pdata = lp->pdata;
267 	const char *name = pdata->name ? : DEFAULT_BL_NAME;
268 
269 	memset(&props, 0, sizeof(props));
270 	props.type = BACKLIGHT_PLATFORM;
271 	props.max_brightness = MAX_BRIGHTNESS;
272 
273 	if (pdata->initial_brightness > props.max_brightness)
274 		pdata->initial_brightness = props.max_brightness;
275 
276 	props.brightness = pdata->initial_brightness;
277 
278 	bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
279 				       &lp855x_bl_ops, &props);
280 	if (IS_ERR(bl))
281 		return PTR_ERR(bl);
282 
283 	lp->bl = bl;
284 
285 	return 0;
286 }
287 
lp855x_get_chip_id(struct device * dev,struct device_attribute * attr,char * buf)288 static ssize_t lp855x_get_chip_id(struct device *dev,
289 				struct device_attribute *attr, char *buf)
290 {
291 	struct lp855x *lp = dev_get_drvdata(dev);
292 
293 	return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
294 }
295 
lp855x_get_bl_ctl_mode(struct device * dev,struct device_attribute * attr,char * buf)296 static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
297 				     struct device_attribute *attr, char *buf)
298 {
299 	struct lp855x *lp = dev_get_drvdata(dev);
300 	char *strmode = NULL;
301 
302 	if (lp->mode == PWM_BASED)
303 		strmode = "pwm based";
304 	else if (lp->mode == REGISTER_BASED)
305 		strmode = "register based";
306 
307 	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
308 }
309 
310 static DEVICE_ATTR(chip_id, S_IRUGO, lp855x_get_chip_id, NULL);
311 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp855x_get_bl_ctl_mode, NULL);
312 
313 static struct attribute *lp855x_attributes[] = {
314 	&dev_attr_chip_id.attr,
315 	&dev_attr_bl_ctl_mode.attr,
316 	NULL,
317 };
318 
319 static const struct attribute_group lp855x_attr_group = {
320 	.attrs = lp855x_attributes,
321 };
322 
323 #ifdef CONFIG_OF
lp855x_parse_dt(struct lp855x * lp)324 static int lp855x_parse_dt(struct lp855x *lp)
325 {
326 	struct device *dev = lp->dev;
327 	struct device_node *node = dev->of_node;
328 	struct lp855x_platform_data *pdata = lp->pdata;
329 	int rom_length;
330 
331 	if (!node) {
332 		dev_err(dev, "no platform data\n");
333 		return -EINVAL;
334 	}
335 
336 	of_property_read_string(node, "bl-name", &pdata->name);
337 	of_property_read_u8(node, "dev-ctrl", &pdata->device_control);
338 	of_property_read_u8(node, "init-brt", &pdata->initial_brightness);
339 	/* Deprecated, specify period in pwms property instead */
340 	of_property_read_u32(node, "pwm-period", &pdata->period_ns);
341 
342 	/* Fill ROM platform data if defined */
343 	rom_length = of_get_child_count(node);
344 	if (rom_length > 0) {
345 		struct lp855x_rom_data *rom;
346 		struct device_node *child;
347 		int i = 0;
348 
349 		rom = devm_kcalloc(dev, rom_length, sizeof(*rom), GFP_KERNEL);
350 		if (!rom)
351 			return -ENOMEM;
352 
353 		for_each_child_of_node(node, child) {
354 			of_property_read_u8(child, "rom-addr", &rom[i].addr);
355 			of_property_read_u8(child, "rom-val", &rom[i].val);
356 			i++;
357 		}
358 
359 		pdata->size_program = rom_length;
360 		pdata->rom_data = &rom[0];
361 	}
362 
363 	return 0;
364 }
365 #else
lp855x_parse_dt(struct lp855x * lp)366 static int lp855x_parse_dt(struct lp855x *lp)
367 {
368 	return -EINVAL;
369 }
370 #endif
371 
lp855x_parse_acpi(struct lp855x * lp)372 static int lp855x_parse_acpi(struct lp855x *lp)
373 {
374 	int ret;
375 
376 	/*
377 	 * On ACPI the device has already been initialized by the firmware
378 	 * and is in register mode, so we can read back the settings from
379 	 * the registers.
380 	 */
381 	ret = i2c_smbus_read_byte_data(lp->client, lp->cfg->reg_brightness);
382 	if (ret < 0)
383 		return ret;
384 
385 	lp->pdata->initial_brightness = ret;
386 
387 	ret = i2c_smbus_read_byte_data(lp->client, lp->cfg->reg_devicectrl);
388 	if (ret < 0)
389 		return ret;
390 
391 	lp->pdata->device_control = ret;
392 	return 0;
393 }
394 
lp855x_probe(struct i2c_client * cl)395 static int lp855x_probe(struct i2c_client *cl)
396 {
397 	const struct i2c_device_id *id = i2c_client_get_device_id(cl);
398 	const struct acpi_device_id *acpi_id = NULL;
399 	struct device *dev = &cl->dev;
400 	struct lp855x *lp;
401 	int ret;
402 
403 	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
404 		return -EIO;
405 
406 	lp = devm_kzalloc(dev, sizeof(struct lp855x), GFP_KERNEL);
407 	if (!lp)
408 		return -ENOMEM;
409 
410 	lp->client = cl;
411 	lp->dev = dev;
412 	lp->pdata = dev_get_platdata(dev);
413 
414 	if (id) {
415 		lp->chipname = id->name;
416 		lp->chip_id = id->driver_data;
417 	} else {
418 		acpi_id = acpi_match_device(dev->driver->acpi_match_table, dev);
419 		if (!acpi_id)
420 			return -ENODEV;
421 
422 		lp->chipname = acpi_id->id;
423 		lp->chip_id = acpi_id->driver_data;
424 	}
425 
426 	switch (lp->chip_id) {
427 	case LP8550:
428 	case LP8551:
429 	case LP8552:
430 	case LP8553:
431 	case LP8556:
432 		lp->cfg = &lp855x_dev_cfg;
433 		break;
434 	case LP8555:
435 	case LP8557:
436 		lp->cfg = &lp8557_dev_cfg;
437 		break;
438 	default:
439 		return -EINVAL;
440 	}
441 
442 	if (!lp->pdata) {
443 		lp->pdata = devm_kzalloc(dev, sizeof(*lp->pdata), GFP_KERNEL);
444 		if (!lp->pdata)
445 			return -ENOMEM;
446 
447 		if (id) {
448 			ret = lp855x_parse_dt(lp);
449 			if (ret < 0)
450 				return ret;
451 		} else {
452 			ret = lp855x_parse_acpi(lp);
453 			if (ret < 0)
454 				return ret;
455 		}
456 	}
457 
458 	lp->supply = devm_regulator_get(dev, "power");
459 	if (IS_ERR(lp->supply)) {
460 		if (PTR_ERR(lp->supply) == -EPROBE_DEFER)
461 			return -EPROBE_DEFER;
462 		lp->supply = NULL;
463 	}
464 
465 	lp->enable = devm_regulator_get_optional(dev, "enable");
466 	if (IS_ERR(lp->enable)) {
467 		ret = PTR_ERR(lp->enable);
468 		if (ret == -ENODEV)
469 			lp->enable = NULL;
470 		else
471 			return dev_err_probe(dev, ret, "getting enable regulator\n");
472 	}
473 
474 	lp->pwm = devm_pwm_get(lp->dev, lp->chipname);
475 	if (IS_ERR(lp->pwm)) {
476 		ret = PTR_ERR(lp->pwm);
477 		if (ret == -ENODEV || ret == -EINVAL)
478 			lp->pwm = NULL;
479 		else
480 			return dev_err_probe(dev, ret, "getting PWM\n");
481 
482 		lp->needs_pwm_init = false;
483 		lp->mode = REGISTER_BASED;
484 		dev_dbg(dev, "mode: register based\n");
485 	} else {
486 		lp->needs_pwm_init = true;
487 		lp->mode = PWM_BASED;
488 		dev_dbg(dev, "mode: PWM based\n");
489 	}
490 
491 	if (lp->supply) {
492 		ret = regulator_enable(lp->supply);
493 		if (ret < 0) {
494 			dev_err(dev, "failed to enable supply: %d\n", ret);
495 			return ret;
496 		}
497 	}
498 
499 	if (lp->enable) {
500 		ret = regulator_enable(lp->enable);
501 		if (ret < 0) {
502 			dev_err(dev, "failed to enable vddio: %d\n", ret);
503 			goto disable_supply;
504 		}
505 
506 		/*
507 		 * LP8555 datasheet says t_RESPONSE (time between VDDIO and
508 		 * I2C) is 1ms.
509 		 */
510 		usleep_range(1000, 2000);
511 	}
512 
513 	i2c_set_clientdata(cl, lp);
514 
515 	ret = lp855x_configure(lp);
516 	if (ret) {
517 		dev_err(dev, "device config err: %d", ret);
518 		goto disable_vddio;
519 	}
520 
521 	ret = lp855x_backlight_register(lp);
522 	if (ret) {
523 		dev_err(dev, "failed to register backlight. err: %d\n", ret);
524 		goto disable_vddio;
525 	}
526 
527 	ret = sysfs_create_group(&dev->kobj, &lp855x_attr_group);
528 	if (ret) {
529 		dev_err(dev, "failed to register sysfs. err: %d\n", ret);
530 		goto disable_vddio;
531 	}
532 
533 	backlight_update_status(lp->bl);
534 
535 	return 0;
536 
537 disable_vddio:
538 	if (lp->enable)
539 		regulator_disable(lp->enable);
540 disable_supply:
541 	if (lp->supply)
542 		regulator_disable(lp->supply);
543 
544 	return ret;
545 }
546 
lp855x_remove(struct i2c_client * cl)547 static void lp855x_remove(struct i2c_client *cl)
548 {
549 	struct lp855x *lp = i2c_get_clientdata(cl);
550 
551 	lp->bl->props.brightness = 0;
552 	backlight_update_status(lp->bl);
553 	if (lp->enable)
554 		regulator_disable(lp->enable);
555 	if (lp->supply)
556 		regulator_disable(lp->supply);
557 	sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
558 }
559 
560 static const struct of_device_id lp855x_dt_ids[] __maybe_unused = {
561 	{ .compatible = "ti,lp8550", },
562 	{ .compatible = "ti,lp8551", },
563 	{ .compatible = "ti,lp8552", },
564 	{ .compatible = "ti,lp8553", },
565 	{ .compatible = "ti,lp8555", },
566 	{ .compatible = "ti,lp8556", },
567 	{ .compatible = "ti,lp8557", },
568 	{ }
569 };
570 MODULE_DEVICE_TABLE(of, lp855x_dt_ids);
571 
572 static const struct i2c_device_id lp855x_ids[] = {
573 	{"lp8550", LP8550},
574 	{"lp8551", LP8551},
575 	{"lp8552", LP8552},
576 	{"lp8553", LP8553},
577 	{"lp8555", LP8555},
578 	{"lp8556", LP8556},
579 	{"lp8557", LP8557},
580 	{ }
581 };
582 MODULE_DEVICE_TABLE(i2c, lp855x_ids);
583 
584 #ifdef CONFIG_ACPI
585 static const struct acpi_device_id lp855x_acpi_match[] = {
586 	/* Xiaomi specific HID used for the LP8556 on the Mi Pad 2 */
587 	{ "XMCC0001", LP8556 },
588 	{ }
589 };
590 MODULE_DEVICE_TABLE(acpi, lp855x_acpi_match);
591 #endif
592 
593 static struct i2c_driver lp855x_driver = {
594 	.driver = {
595 		   .name = "lp855x",
596 		   .of_match_table = of_match_ptr(lp855x_dt_ids),
597 		   .acpi_match_table = ACPI_PTR(lp855x_acpi_match),
598 		   },
599 	.probe = lp855x_probe,
600 	.remove = lp855x_remove,
601 	.id_table = lp855x_ids,
602 };
603 
604 module_i2c_driver(lp855x_driver);
605 
606 MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
607 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
608 MODULE_LICENSE("GPL");
609