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