1 /*
2  * TI LP855x Backlight Driver
3  *
4  *			Copyright (C) 2011 Texas Instruments
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  *
10  */
11 
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/i2c.h>
15 #include <linux/backlight.h>
16 #include <linux/err.h>
17 #include <linux/of.h>
18 #include <linux/platform_data/lp855x.h>
19 #include <linux/pwm.h>
20 
21 /* LP8550/1/2/3/6 Registers */
22 #define LP855X_BRIGHTNESS_CTRL		0x00
23 #define LP855X_DEVICE_CTRL		0x01
24 #define LP855X_EEPROM_START		0xA0
25 #define LP855X_EEPROM_END		0xA7
26 #define LP8556_EPROM_START		0xA0
27 #define LP8556_EPROM_END		0xAF
28 
29 /* LP8555/7 Registers */
30 #define LP8557_BL_CMD			0x00
31 #define LP8557_BL_MASK			0x01
32 #define LP8557_BL_ON			0x01
33 #define LP8557_BL_OFF			0x00
34 #define LP8557_BRIGHTNESS_CTRL		0x04
35 #define LP8557_CONFIG			0x10
36 #define LP8555_EPROM_START		0x10
37 #define LP8555_EPROM_END		0x7A
38 #define LP8557_EPROM_START		0x10
39 #define LP8557_EPROM_END		0x1E
40 
41 #define DEFAULT_BL_NAME		"lcd-backlight"
42 #define MAX_BRIGHTNESS		255
43 
44 enum lp855x_brightness_ctrl_mode {
45 	PWM_BASED = 1,
46 	REGISTER_BASED,
47 };
48 
49 struct lp855x;
50 
51 /*
52  * struct lp855x_device_config
53  * @pre_init_device: init device function call before updating the brightness
54  * @reg_brightness: register address for brigthenss control
55  * @reg_devicectrl: register address for device control
56  * @post_init_device: late init device function call
57  */
58 struct lp855x_device_config {
59 	int (*pre_init_device)(struct lp855x *);
60 	u8 reg_brightness;
61 	u8 reg_devicectrl;
62 	int (*post_init_device)(struct lp855x *);
63 };
64 
65 struct lp855x {
66 	const char *chipname;
67 	enum lp855x_chip_id chip_id;
68 	enum lp855x_brightness_ctrl_mode mode;
69 	struct lp855x_device_config *cfg;
70 	struct i2c_client *client;
71 	struct backlight_device *bl;
72 	struct device *dev;
73 	struct lp855x_platform_data *pdata;
74 	struct pwm_device *pwm;
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 	pwm_config(lp->pwm, duty, period);
250 	if (duty)
251 		pwm_enable(lp->pwm);
252 	else
253 		pwm_disable(lp->pwm);
254 }
255 
256 static int lp855x_bl_update_status(struct backlight_device *bl)
257 {
258 	struct lp855x *lp = bl_get_data(bl);
259 
260 	if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
261 		bl->props.brightness = 0;
262 
263 	if (lp->mode == PWM_BASED) {
264 		int br = bl->props.brightness;
265 		int max_br = bl->props.max_brightness;
266 
267 		lp855x_pwm_ctrl(lp, br, max_br);
268 
269 	} else if (lp->mode == REGISTER_BASED) {
270 		u8 val = bl->props.brightness;
271 
272 		lp855x_write_byte(lp, lp->cfg->reg_brightness, val);
273 	}
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 	props.type = BACKLIGHT_PLATFORM;
291 	props.max_brightness = MAX_BRIGHTNESS;
292 
293 	if (pdata->initial_brightness > props.max_brightness)
294 		pdata->initial_brightness = props.max_brightness;
295 
296 	props.brightness = pdata->initial_brightness;
297 
298 	bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
299 				       &lp855x_bl_ops, &props);
300 	if (IS_ERR(bl))
301 		return PTR_ERR(bl);
302 
303 	lp->bl = bl;
304 
305 	return 0;
306 }
307 
308 static ssize_t lp855x_get_chip_id(struct device *dev,
309 				struct device_attribute *attr, char *buf)
310 {
311 	struct lp855x *lp = dev_get_drvdata(dev);
312 
313 	return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
314 }
315 
316 static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
317 				     struct device_attribute *attr, char *buf)
318 {
319 	struct lp855x *lp = dev_get_drvdata(dev);
320 	char *strmode = NULL;
321 
322 	if (lp->mode == PWM_BASED)
323 		strmode = "pwm based";
324 	else if (lp->mode == REGISTER_BASED)
325 		strmode = "register based";
326 
327 	return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
328 }
329 
330 static DEVICE_ATTR(chip_id, S_IRUGO, lp855x_get_chip_id, NULL);
331 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp855x_get_bl_ctl_mode, NULL);
332 
333 static struct attribute *lp855x_attributes[] = {
334 	&dev_attr_chip_id.attr,
335 	&dev_attr_bl_ctl_mode.attr,
336 	NULL,
337 };
338 
339 static const struct attribute_group lp855x_attr_group = {
340 	.attrs = lp855x_attributes,
341 };
342 
343 #ifdef CONFIG_OF
344 static int lp855x_parse_dt(struct device *dev, struct device_node *node)
345 {
346 	struct lp855x_platform_data *pdata;
347 	int rom_length;
348 
349 	if (!node) {
350 		dev_err(dev, "no platform data\n");
351 		return -EINVAL;
352 	}
353 
354 	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
355 	if (!pdata)
356 		return -ENOMEM;
357 
358 	of_property_read_string(node, "bl-name", &pdata->name);
359 	of_property_read_u8(node, "dev-ctrl", &pdata->device_control);
360 	of_property_read_u8(node, "init-brt", &pdata->initial_brightness);
361 	of_property_read_u32(node, "pwm-period", &pdata->period_ns);
362 
363 	/* Fill ROM platform data if defined */
364 	rom_length = of_get_child_count(node);
365 	if (rom_length > 0) {
366 		struct lp855x_rom_data *rom;
367 		struct device_node *child;
368 		int i = 0;
369 
370 		rom = devm_kzalloc(dev, sizeof(*rom) * rom_length, GFP_KERNEL);
371 		if (!rom)
372 			return -ENOMEM;
373 
374 		for_each_child_of_node(node, child) {
375 			of_property_read_u8(child, "rom-addr", &rom[i].addr);
376 			of_property_read_u8(child, "rom-val", &rom[i].val);
377 			i++;
378 		}
379 
380 		pdata->size_program = rom_length;
381 		pdata->rom_data = &rom[0];
382 	}
383 
384 	dev->platform_data = pdata;
385 
386 	return 0;
387 }
388 #else
389 static int lp855x_parse_dt(struct device *dev, struct device_node *node)
390 {
391 	return -EINVAL;
392 }
393 #endif
394 
395 static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
396 {
397 	struct lp855x *lp;
398 	struct lp855x_platform_data *pdata = dev_get_platdata(&cl->dev);
399 	struct device_node *node = cl->dev.of_node;
400 	int ret;
401 
402 	if (!pdata) {
403 		ret = lp855x_parse_dt(&cl->dev, node);
404 		if (ret < 0)
405 			return ret;
406 
407 		pdata = dev_get_platdata(&cl->dev);
408 	}
409 
410 	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
411 		return -EIO;
412 
413 	lp = devm_kzalloc(&cl->dev, sizeof(struct lp855x), GFP_KERNEL);
414 	if (!lp)
415 		return -ENOMEM;
416 
417 	if (pdata->period_ns > 0)
418 		lp->mode = PWM_BASED;
419 	else
420 		lp->mode = REGISTER_BASED;
421 
422 	lp->client = cl;
423 	lp->dev = &cl->dev;
424 	lp->pdata = pdata;
425 	lp->chipname = id->name;
426 	lp->chip_id = id->driver_data;
427 	i2c_set_clientdata(cl, lp);
428 
429 	ret = lp855x_configure(lp);
430 	if (ret) {
431 		dev_err(lp->dev, "device config err: %d", ret);
432 		return ret;
433 	}
434 
435 	ret = lp855x_backlight_register(lp);
436 	if (ret) {
437 		dev_err(lp->dev,
438 			"failed to register backlight. err: %d\n", ret);
439 		return ret;
440 	}
441 
442 	ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
443 	if (ret) {
444 		dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
445 		return ret;
446 	}
447 
448 	backlight_update_status(lp->bl);
449 	return 0;
450 }
451 
452 static int lp855x_remove(struct i2c_client *cl)
453 {
454 	struct lp855x *lp = i2c_get_clientdata(cl);
455 
456 	lp->bl->props.brightness = 0;
457 	backlight_update_status(lp->bl);
458 	sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
459 
460 	return 0;
461 }
462 
463 static const struct of_device_id lp855x_dt_ids[] = {
464 	{ .compatible = "ti,lp8550", },
465 	{ .compatible = "ti,lp8551", },
466 	{ .compatible = "ti,lp8552", },
467 	{ .compatible = "ti,lp8553", },
468 	{ .compatible = "ti,lp8555", },
469 	{ .compatible = "ti,lp8556", },
470 	{ .compatible = "ti,lp8557", },
471 	{ }
472 };
473 MODULE_DEVICE_TABLE(of, lp855x_dt_ids);
474 
475 static const struct i2c_device_id lp855x_ids[] = {
476 	{"lp8550", LP8550},
477 	{"lp8551", LP8551},
478 	{"lp8552", LP8552},
479 	{"lp8553", LP8553},
480 	{"lp8555", LP8555},
481 	{"lp8556", LP8556},
482 	{"lp8557", LP8557},
483 	{ }
484 };
485 MODULE_DEVICE_TABLE(i2c, lp855x_ids);
486 
487 static struct i2c_driver lp855x_driver = {
488 	.driver = {
489 		   .name = "lp855x",
490 		   .of_match_table = of_match_ptr(lp855x_dt_ids),
491 		   },
492 	.probe = lp855x_probe,
493 	.remove = lp855x_remove,
494 	.id_table = lp855x_ids,
495 };
496 
497 module_i2c_driver(lp855x_driver);
498 
499 MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
500 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
501 MODULE_LICENSE("GPL");
502