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 #include <linux/regulator/consumer.h>
21
22 /* LP8550/1/2/3/6 Registers */
23 #define LP855X_BRIGHTNESS_CTRL 0x00
24 #define LP855X_DEVICE_CTRL 0x01
25 #define LP855X_EEPROM_START 0xA0
26 #define LP855X_EEPROM_END 0xA7
27 #define LP8556_EPROM_START 0xA0
28 #define LP8556_EPROM_END 0xAF
29
30 /* LP8555/7 Registers */
31 #define LP8557_BL_CMD 0x00
32 #define LP8557_BL_MASK 0x01
33 #define LP8557_BL_ON 0x01
34 #define LP8557_BL_OFF 0x00
35 #define LP8557_BRIGHTNESS_CTRL 0x04
36 #define LP8557_CONFIG 0x10
37 #define LP8555_EPROM_START 0x10
38 #define LP8555_EPROM_END 0x7A
39 #define LP8557_EPROM_START 0x10
40 #define LP8557_EPROM_END 0x1E
41
42 #define DEFAULT_BL_NAME "lcd-backlight"
43 #define MAX_BRIGHTNESS 255
44
45 enum lp855x_brightness_ctrl_mode {
46 PWM_BASED = 1,
47 REGISTER_BASED,
48 };
49
50 struct lp855x;
51
52 /*
53 * struct lp855x_device_config
54 * @pre_init_device: init device function call before updating the brightness
55 * @reg_brightness: register address for brigthenss control
56 * @reg_devicectrl: register address for device control
57 * @post_init_device: late init device function call
58 */
59 struct lp855x_device_config {
60 int (*pre_init_device)(struct lp855x *);
61 u8 reg_brightness;
62 u8 reg_devicectrl;
63 int (*post_init_device)(struct lp855x *);
64 };
65
66 struct lp855x {
67 const char *chipname;
68 enum lp855x_chip_id chip_id;
69 enum lp855x_brightness_ctrl_mode mode;
70 struct lp855x_device_config *cfg;
71 struct i2c_client *client;
72 struct backlight_device *bl;
73 struct device *dev;
74 struct lp855x_platform_data *pdata;
75 struct pwm_device *pwm;
76 struct regulator *supply; /* regulator for VDD 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 switch (lp->chip_id) {
176 case LP8550:
177 case LP8551:
178 case LP8552:
179 case LP8553:
180 case LP8556:
181 lp->cfg = &lp855x_dev_cfg;
182 break;
183 case LP8555:
184 case LP8557:
185 lp->cfg = &lp8557_dev_cfg;
186 break;
187 default:
188 return -EINVAL;
189 }
190
191 if (lp->cfg->pre_init_device) {
192 ret = lp->cfg->pre_init_device(lp);
193 if (ret) {
194 dev_err(lp->dev, "pre init device err: %d\n", ret);
195 goto err;
196 }
197 }
198
199 val = pd->initial_brightness;
200 ret = lp855x_write_byte(lp, lp->cfg->reg_brightness, val);
201 if (ret)
202 goto err;
203
204 val = pd->device_control;
205 ret = lp855x_write_byte(lp, lp->cfg->reg_devicectrl, val);
206 if (ret)
207 goto err;
208
209 if (pd->size_program > 0) {
210 for (i = 0; i < pd->size_program; i++) {
211 addr = pd->rom_data[i].addr;
212 val = pd->rom_data[i].val;
213 if (!lp855x_is_valid_rom_area(lp, addr))
214 continue;
215
216 ret = lp855x_write_byte(lp, addr, val);
217 if (ret)
218 goto err;
219 }
220 }
221
222 if (lp->cfg->post_init_device) {
223 ret = lp->cfg->post_init_device(lp);
224 if (ret) {
225 dev_err(lp->dev, "post init device err: %d\n", ret);
226 goto err;
227 }
228 }
229
230 return 0;
231
232 err:
233 return ret;
234 }
235
lp855x_pwm_ctrl(struct lp855x * lp,int br,int max_br)236 static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
237 {
238 unsigned int period = lp->pdata->period_ns;
239 unsigned int duty = br * period / max_br;
240 struct pwm_device *pwm;
241
242 /* request pwm device with the consumer name */
243 if (!lp->pwm) {
244 pwm = devm_pwm_get(lp->dev, lp->chipname);
245 if (IS_ERR(pwm))
246 return;
247
248 lp->pwm = pwm;
249 }
250
251 pwm_config(lp->pwm, duty, period);
252 if (duty)
253 pwm_enable(lp->pwm);
254 else
255 pwm_disable(lp->pwm);
256 }
257
lp855x_bl_update_status(struct backlight_device * bl)258 static int lp855x_bl_update_status(struct backlight_device *bl)
259 {
260 struct lp855x *lp = bl_get_data(bl);
261 int brightness = bl->props.brightness;
262
263 if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
264 brightness = 0;
265
266 if (lp->mode == PWM_BASED)
267 lp855x_pwm_ctrl(lp, brightness, bl->props.max_brightness);
268 else if (lp->mode == REGISTER_BASED)
269 lp855x_write_byte(lp, lp->cfg->reg_brightness, (u8)brightness);
270
271 return 0;
272 }
273
274 static const struct backlight_ops lp855x_bl_ops = {
275 .options = BL_CORE_SUSPENDRESUME,
276 .update_status = lp855x_bl_update_status,
277 };
278
lp855x_backlight_register(struct lp855x * lp)279 static int lp855x_backlight_register(struct lp855x *lp)
280 {
281 struct backlight_device *bl;
282 struct backlight_properties props;
283 struct lp855x_platform_data *pdata = lp->pdata;
284 const char *name = pdata->name ? : DEFAULT_BL_NAME;
285
286 memset(&props, 0, sizeof(props));
287 props.type = BACKLIGHT_PLATFORM;
288 props.max_brightness = MAX_BRIGHTNESS;
289
290 if (pdata->initial_brightness > props.max_brightness)
291 pdata->initial_brightness = props.max_brightness;
292
293 props.brightness = pdata->initial_brightness;
294
295 bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
296 &lp855x_bl_ops, &props);
297 if (IS_ERR(bl))
298 return PTR_ERR(bl);
299
300 lp->bl = bl;
301
302 return 0;
303 }
304
lp855x_get_chip_id(struct device * dev,struct device_attribute * attr,char * buf)305 static ssize_t lp855x_get_chip_id(struct device *dev,
306 struct device_attribute *attr, char *buf)
307 {
308 struct lp855x *lp = dev_get_drvdata(dev);
309
310 return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
311 }
312
lp855x_get_bl_ctl_mode(struct device * dev,struct device_attribute * attr,char * buf)313 static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
314 struct device_attribute *attr, char *buf)
315 {
316 struct lp855x *lp = dev_get_drvdata(dev);
317 char *strmode = NULL;
318
319 if (lp->mode == PWM_BASED)
320 strmode = "pwm based";
321 else if (lp->mode == REGISTER_BASED)
322 strmode = "register based";
323
324 return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
325 }
326
327 static DEVICE_ATTR(chip_id, S_IRUGO, lp855x_get_chip_id, NULL);
328 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp855x_get_bl_ctl_mode, NULL);
329
330 static struct attribute *lp855x_attributes[] = {
331 &dev_attr_chip_id.attr,
332 &dev_attr_bl_ctl_mode.attr,
333 NULL,
334 };
335
336 static const struct attribute_group lp855x_attr_group = {
337 .attrs = lp855x_attributes,
338 };
339
340 #ifdef CONFIG_OF
lp855x_parse_dt(struct lp855x * lp)341 static int lp855x_parse_dt(struct lp855x *lp)
342 {
343 struct device *dev = lp->dev;
344 struct device_node *node = dev->of_node;
345 struct lp855x_platform_data *pdata;
346 int rom_length;
347
348 if (!node) {
349 dev_err(dev, "no platform data\n");
350 return -EINVAL;
351 }
352
353 pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
354 if (!pdata)
355 return -ENOMEM;
356
357 of_property_read_string(node, "bl-name", &pdata->name);
358 of_property_read_u8(node, "dev-ctrl", &pdata->device_control);
359 of_property_read_u8(node, "init-brt", &pdata->initial_brightness);
360 of_property_read_u32(node, "pwm-period", &pdata->period_ns);
361
362 /* Fill ROM platform data if defined */
363 rom_length = of_get_child_count(node);
364 if (rom_length > 0) {
365 struct lp855x_rom_data *rom;
366 struct device_node *child;
367 int i = 0;
368
369 rom = devm_kzalloc(dev, sizeof(*rom) * rom_length, GFP_KERNEL);
370 if (!rom)
371 return -ENOMEM;
372
373 for_each_child_of_node(node, child) {
374 of_property_read_u8(child, "rom-addr", &rom[i].addr);
375 of_property_read_u8(child, "rom-val", &rom[i].val);
376 i++;
377 }
378
379 pdata->size_program = rom_length;
380 pdata->rom_data = &rom[0];
381 }
382
383 lp->pdata = pdata;
384
385 return 0;
386 }
387 #else
lp855x_parse_dt(struct lp855x * lp)388 static int lp855x_parse_dt(struct lp855x *lp)
389 {
390 return -EINVAL;
391 }
392 #endif
393
lp855x_probe(struct i2c_client * cl,const struct i2c_device_id * id)394 static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
395 {
396 struct lp855x *lp;
397 int ret;
398
399 if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
400 return -EIO;
401
402 lp = devm_kzalloc(&cl->dev, sizeof(struct lp855x), GFP_KERNEL);
403 if (!lp)
404 return -ENOMEM;
405
406 lp->client = cl;
407 lp->dev = &cl->dev;
408 lp->chipname = id->name;
409 lp->chip_id = id->driver_data;
410 lp->pdata = dev_get_platdata(&cl->dev);
411
412 if (!lp->pdata) {
413 ret = lp855x_parse_dt(lp);
414 if (ret < 0)
415 return ret;
416 }
417
418 if (lp->pdata->period_ns > 0)
419 lp->mode = PWM_BASED;
420 else
421 lp->mode = REGISTER_BASED;
422
423 lp->supply = devm_regulator_get(lp->dev, "power");
424 if (IS_ERR(lp->supply)) {
425 if (PTR_ERR(lp->supply) == -EPROBE_DEFER)
426 return -EPROBE_DEFER;
427 lp->supply = NULL;
428 }
429
430 if (lp->supply) {
431 ret = regulator_enable(lp->supply);
432 if (ret < 0) {
433 dev_err(&cl->dev, "failed to enable supply: %d\n", ret);
434 return ret;
435 }
436 }
437
438 i2c_set_clientdata(cl, lp);
439
440 ret = lp855x_configure(lp);
441 if (ret) {
442 dev_err(lp->dev, "device config err: %d", ret);
443 return ret;
444 }
445
446 ret = lp855x_backlight_register(lp);
447 if (ret) {
448 dev_err(lp->dev,
449 "failed to register backlight. err: %d\n", ret);
450 return ret;
451 }
452
453 ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
454 if (ret) {
455 dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
456 return ret;
457 }
458
459 backlight_update_status(lp->bl);
460 return 0;
461 }
462
lp855x_remove(struct i2c_client * cl)463 static int lp855x_remove(struct i2c_client *cl)
464 {
465 struct lp855x *lp = i2c_get_clientdata(cl);
466
467 lp->bl->props.brightness = 0;
468 backlight_update_status(lp->bl);
469 if (lp->supply)
470 regulator_disable(lp->supply);
471 sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
472
473 return 0;
474 }
475
476 static const struct of_device_id lp855x_dt_ids[] = {
477 { .compatible = "ti,lp8550", },
478 { .compatible = "ti,lp8551", },
479 { .compatible = "ti,lp8552", },
480 { .compatible = "ti,lp8553", },
481 { .compatible = "ti,lp8555", },
482 { .compatible = "ti,lp8556", },
483 { .compatible = "ti,lp8557", },
484 { }
485 };
486 MODULE_DEVICE_TABLE(of, lp855x_dt_ids);
487
488 static const struct i2c_device_id lp855x_ids[] = {
489 {"lp8550", LP8550},
490 {"lp8551", LP8551},
491 {"lp8552", LP8552},
492 {"lp8553", LP8553},
493 {"lp8555", LP8555},
494 {"lp8556", LP8556},
495 {"lp8557", LP8557},
496 { }
497 };
498 MODULE_DEVICE_TABLE(i2c, lp855x_ids);
499
500 static struct i2c_driver lp855x_driver = {
501 .driver = {
502 .name = "lp855x",
503 .of_match_table = of_match_ptr(lp855x_dt_ids),
504 },
505 .probe = lp855x_probe,
506 .remove = lp855x_remove,
507 .id_table = lp855x_ids,
508 };
509
510 module_i2c_driver(lp855x_driver);
511
512 MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
513 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
514 MODULE_LICENSE("GPL");
515