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 };
77
lp855x_write_byte(struct lp855x * lp,u8 reg,u8 data)78 static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
79 {
80 return i2c_smbus_write_byte_data(lp->client, reg, data);
81 }
82
lp855x_update_bit(struct lp855x * lp,u8 reg,u8 mask,u8 data)83 static int lp855x_update_bit(struct lp855x *lp, u8 reg, u8 mask, u8 data)
84 {
85 int ret;
86 u8 tmp;
87
88 ret = i2c_smbus_read_byte_data(lp->client, reg);
89 if (ret < 0) {
90 dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
91 return ret;
92 }
93
94 tmp = (u8)ret;
95 tmp &= ~mask;
96 tmp |= data & mask;
97
98 return lp855x_write_byte(lp, reg, tmp);
99 }
100
lp855x_is_valid_rom_area(struct lp855x * lp,u8 addr)101 static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
102 {
103 u8 start, end;
104
105 switch (lp->chip_id) {
106 case LP8550:
107 case LP8551:
108 case LP8552:
109 case LP8553:
110 start = LP855X_EEPROM_START;
111 end = LP855X_EEPROM_END;
112 break;
113 case LP8556:
114 start = LP8556_EPROM_START;
115 end = LP8556_EPROM_END;
116 break;
117 case LP8555:
118 start = LP8555_EPROM_START;
119 end = LP8555_EPROM_END;
120 break;
121 case LP8557:
122 start = LP8557_EPROM_START;
123 end = LP8557_EPROM_END;
124 break;
125 default:
126 return false;
127 }
128
129 return addr >= start && addr <= end;
130 }
131
lp8557_bl_off(struct lp855x * lp)132 static int lp8557_bl_off(struct lp855x *lp)
133 {
134 /* BL_ON = 0 before updating EPROM settings */
135 return lp855x_update_bit(lp, LP8557_BL_CMD, LP8557_BL_MASK,
136 LP8557_BL_OFF);
137 }
138
lp8557_bl_on(struct lp855x * lp)139 static int lp8557_bl_on(struct lp855x *lp)
140 {
141 /* BL_ON = 1 after updating EPROM settings */
142 return lp855x_update_bit(lp, LP8557_BL_CMD, LP8557_BL_MASK,
143 LP8557_BL_ON);
144 }
145
146 static struct lp855x_device_config lp855x_dev_cfg = {
147 .reg_brightness = LP855X_BRIGHTNESS_CTRL,
148 .reg_devicectrl = LP855X_DEVICE_CTRL,
149 };
150
151 static struct lp855x_device_config lp8557_dev_cfg = {
152 .reg_brightness = LP8557_BRIGHTNESS_CTRL,
153 .reg_devicectrl = LP8557_CONFIG,
154 .pre_init_device = lp8557_bl_off,
155 .post_init_device = lp8557_bl_on,
156 };
157
158 /*
159 * Device specific configuration flow
160 *
161 * a) pre_init_device(optional)
162 * b) update the brightness register
163 * c) update device control register
164 * d) update ROM area(optional)
165 * e) post_init_device(optional)
166 *
167 */
lp855x_configure(struct lp855x * lp)168 static int lp855x_configure(struct lp855x *lp)
169 {
170 u8 val, addr;
171 int i, ret;
172 struct lp855x_platform_data *pd = lp->pdata;
173
174 switch (lp->chip_id) {
175 case LP8550:
176 case LP8551:
177 case LP8552:
178 case LP8553:
179 case LP8556:
180 lp->cfg = &lp855x_dev_cfg;
181 break;
182 case LP8555:
183 case LP8557:
184 lp->cfg = &lp8557_dev_cfg;
185 break;
186 default:
187 return -EINVAL;
188 }
189
190 if (lp->cfg->pre_init_device) {
191 ret = lp->cfg->pre_init_device(lp);
192 if (ret) {
193 dev_err(lp->dev, "pre init device err: %d\n", ret);
194 goto err;
195 }
196 }
197
198 val = pd->initial_brightness;
199 ret = lp855x_write_byte(lp, lp->cfg->reg_brightness, val);
200 if (ret)
201 goto err;
202
203 val = pd->device_control;
204 ret = lp855x_write_byte(lp, lp->cfg->reg_devicectrl, val);
205 if (ret)
206 goto err;
207
208 if (pd->size_program > 0) {
209 for (i = 0; i < pd->size_program; i++) {
210 addr = pd->rom_data[i].addr;
211 val = pd->rom_data[i].val;
212 if (!lp855x_is_valid_rom_area(lp, addr))
213 continue;
214
215 ret = lp855x_write_byte(lp, addr, val);
216 if (ret)
217 goto err;
218 }
219 }
220
221 if (lp->cfg->post_init_device) {
222 ret = lp->cfg->post_init_device(lp);
223 if (ret) {
224 dev_err(lp->dev, "post init device err: %d\n", ret);
225 goto err;
226 }
227 }
228
229 return 0;
230
231 err:
232 return ret;
233 }
234
lp855x_pwm_ctrl(struct lp855x * lp,int br,int max_br)235 static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
236 {
237 unsigned int period = lp->pdata->period_ns;
238 unsigned int duty = br * period / max_br;
239 struct pwm_device *pwm;
240
241 /* request pwm device with the consumer name */
242 if (!lp->pwm) {
243 pwm = devm_pwm_get(lp->dev, lp->chipname);
244 if (IS_ERR(pwm))
245 return;
246
247 lp->pwm = pwm;
248 }
249
250 pwm_config(lp->pwm, duty, period);
251 if (duty)
252 pwm_enable(lp->pwm);
253 else
254 pwm_disable(lp->pwm);
255 }
256
lp855x_bl_update_status(struct backlight_device * bl)257 static int lp855x_bl_update_status(struct backlight_device *bl)
258 {
259 struct lp855x *lp = bl_get_data(bl);
260
261 if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
262 bl->props.brightness = 0;
263
264 if (lp->mode == PWM_BASED) {
265 int br = bl->props.brightness;
266 int max_br = bl->props.max_brightness;
267
268 lp855x_pwm_ctrl(lp, br, max_br);
269
270 } else if (lp->mode == REGISTER_BASED) {
271 u8 val = bl->props.brightness;
272
273 lp855x_write_byte(lp, lp->cfg->reg_brightness, val);
274 }
275
276 return 0;
277 }
278
279 static const struct backlight_ops lp855x_bl_ops = {
280 .options = BL_CORE_SUSPENDRESUME,
281 .update_status = lp855x_bl_update_status,
282 };
283
lp855x_backlight_register(struct lp855x * lp)284 static int lp855x_backlight_register(struct lp855x *lp)
285 {
286 struct backlight_device *bl;
287 struct backlight_properties props;
288 struct lp855x_platform_data *pdata = lp->pdata;
289 const char *name = pdata->name ? : DEFAULT_BL_NAME;
290
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
lp855x_get_chip_id(struct device * dev,struct device_attribute * attr,char * buf)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
lp855x_get_bl_ctl_mode(struct device * dev,struct device_attribute * attr,char * buf)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
lp855x_parse_dt(struct lp855x * lp)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_kzalloc(dev, sizeof(*rom) * rom_length, 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 pdata->supply = devm_regulator_get(dev, "power");
388 if (IS_ERR(pdata->supply)) {
389 if (PTR_ERR(pdata->supply) == -EPROBE_DEFER)
390 return -EPROBE_DEFER;
391 pdata->supply = NULL;
392 }
393
394 lp->pdata = pdata;
395
396 return 0;
397 }
398 #else
lp855x_parse_dt(struct lp855x * lp)399 static int lp855x_parse_dt(struct lp855x *lp)
400 {
401 return -EINVAL;
402 }
403 #endif
404
lp855x_probe(struct i2c_client * cl,const struct i2c_device_id * id)405 static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
406 {
407 struct lp855x *lp;
408 int ret;
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 lp->client = cl;
418 lp->dev = &cl->dev;
419 lp->chipname = id->name;
420 lp->chip_id = id->driver_data;
421 lp->pdata = dev_get_platdata(&cl->dev);
422
423 if (!lp->pdata) {
424 ret = lp855x_parse_dt(lp);
425 if (ret < 0)
426 return ret;
427 }
428
429 if (lp->pdata->period_ns > 0)
430 lp->mode = PWM_BASED;
431 else
432 lp->mode = REGISTER_BASED;
433
434 if (lp->pdata->supply) {
435 ret = regulator_enable(lp->pdata->supply);
436 if (ret < 0) {
437 dev_err(&cl->dev, "failed to enable supply: %d\n", ret);
438 return ret;
439 }
440 }
441
442 i2c_set_clientdata(cl, lp);
443
444 ret = lp855x_configure(lp);
445 if (ret) {
446 dev_err(lp->dev, "device config err: %d", ret);
447 return ret;
448 }
449
450 ret = lp855x_backlight_register(lp);
451 if (ret) {
452 dev_err(lp->dev,
453 "failed to register backlight. err: %d\n", ret);
454 return ret;
455 }
456
457 ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
458 if (ret) {
459 dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
460 return ret;
461 }
462
463 backlight_update_status(lp->bl);
464 return 0;
465 }
466
lp855x_remove(struct i2c_client * cl)467 static int lp855x_remove(struct i2c_client *cl)
468 {
469 struct lp855x *lp = i2c_get_clientdata(cl);
470
471 lp->bl->props.brightness = 0;
472 backlight_update_status(lp->bl);
473 if (lp->pdata->supply)
474 regulator_disable(lp->pdata->supply);
475 sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
476
477 return 0;
478 }
479
480 static const struct of_device_id lp855x_dt_ids[] = {
481 { .compatible = "ti,lp8550", },
482 { .compatible = "ti,lp8551", },
483 { .compatible = "ti,lp8552", },
484 { .compatible = "ti,lp8553", },
485 { .compatible = "ti,lp8555", },
486 { .compatible = "ti,lp8556", },
487 { .compatible = "ti,lp8557", },
488 { }
489 };
490 MODULE_DEVICE_TABLE(of, lp855x_dt_ids);
491
492 static const struct i2c_device_id lp855x_ids[] = {
493 {"lp8550", LP8550},
494 {"lp8551", LP8551},
495 {"lp8552", LP8552},
496 {"lp8553", LP8553},
497 {"lp8555", LP8555},
498 {"lp8556", LP8556},
499 {"lp8557", LP8557},
500 { }
501 };
502 MODULE_DEVICE_TABLE(i2c, lp855x_ids);
503
504 static struct i2c_driver lp855x_driver = {
505 .driver = {
506 .name = "lp855x",
507 .of_match_table = of_match_ptr(lp855x_dt_ids),
508 },
509 .probe = lp855x_probe,
510 .remove = lp855x_remove,
511 .id_table = lp855x_ids,
512 };
513
514 module_i2c_driver(lp855x_driver);
515
516 MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
517 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
518 MODULE_LICENSE("GPL");
519