2 * TI LP855x Backlight Driver
4 * Copyright (C) 2011 Texas Instruments
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.
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>
18 #include <linux/platform_data/lp855x.h>
19 #include <linux/pwm.h>
20 #include <linux/regulator/consumer.h>
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
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
42 #define DEFAULT_BL_NAME "lcd-backlight"
43 #define MAX_BRIGHTNESS 255
45 enum lp855x_brightness_ctrl_mode {
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
59 struct lp855x_device_config {
60 int (*pre_init_device)(struct lp855x *);
63 int (*post_init_device)(struct lp855x *);
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;
74 struct lp855x_platform_data *pdata;
75 struct pwm_device *pwm;
76 struct regulator *supply; /* regulator for VDD input */
79 static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
81 return i2c_smbus_write_byte_data(lp->client, reg, data);
84 static int lp855x_update_bit(struct lp855x *lp, u8 reg, u8 mask, u8 data)
89 ret = i2c_smbus_read_byte_data(lp->client, reg);
91 dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
99 return lp855x_write_byte(lp, reg, tmp);
102 static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
106 switch (lp->chip_id) {
111 start = LP855X_EEPROM_START;
112 end = LP855X_EEPROM_END;
115 start = LP8556_EPROM_START;
116 end = LP8556_EPROM_END;
119 start = LP8555_EPROM_START;
120 end = LP8555_EPROM_END;
123 start = LP8557_EPROM_START;
124 end = LP8557_EPROM_END;
130 return addr >= start && addr <= end;
133 static int lp8557_bl_off(struct lp855x *lp)
135 /* BL_ON = 0 before updating EPROM settings */
136 return lp855x_update_bit(lp, LP8557_BL_CMD, LP8557_BL_MASK,
140 static int lp8557_bl_on(struct lp855x *lp)
142 /* BL_ON = 1 after updating EPROM settings */
143 return lp855x_update_bit(lp, LP8557_BL_CMD, LP8557_BL_MASK,
147 static struct lp855x_device_config lp855x_dev_cfg = {
148 .reg_brightness = LP855X_BRIGHTNESS_CTRL,
149 .reg_devicectrl = LP855X_DEVICE_CTRL,
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,
160 * Device specific configuration flow
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)
169 static int lp855x_configure(struct lp855x *lp)
173 struct lp855x_platform_data *pd = lp->pdata;
175 switch (lp->chip_id) {
181 lp->cfg = &lp855x_dev_cfg;
185 lp->cfg = &lp8557_dev_cfg;
191 if (lp->cfg->pre_init_device) {
192 ret = lp->cfg->pre_init_device(lp);
194 dev_err(lp->dev, "pre init device err: %d\n", ret);
199 val = pd->initial_brightness;
200 ret = lp855x_write_byte(lp, lp->cfg->reg_brightness, val);
204 val = pd->device_control;
205 ret = lp855x_write_byte(lp, lp->cfg->reg_devicectrl, val);
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))
216 ret = lp855x_write_byte(lp, addr, val);
222 if (lp->cfg->post_init_device) {
223 ret = lp->cfg->post_init_device(lp);
225 dev_err(lp->dev, "post init device err: %d\n", ret);
236 static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
238 unsigned int period = lp->pdata->period_ns;
239 unsigned int duty = br * period / max_br;
240 struct pwm_device *pwm;
242 /* request pwm device with the consumer name */
244 pwm = devm_pwm_get(lp->dev, lp->chipname);
251 pwm_config(lp->pwm, duty, period);
255 pwm_disable(lp->pwm);
258 static int lp855x_bl_update_status(struct backlight_device *bl)
260 struct lp855x *lp = bl_get_data(bl);
261 int brightness = bl->props.brightness;
263 if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
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);
274 static const struct backlight_ops lp855x_bl_ops = {
275 .options = BL_CORE_SUSPENDRESUME,
276 .update_status = lp855x_bl_update_status,
279 static int lp855x_backlight_register(struct lp855x *lp)
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;
286 props.type = BACKLIGHT_PLATFORM;
287 props.max_brightness = MAX_BRIGHTNESS;
289 if (pdata->initial_brightness > props.max_brightness)
290 pdata->initial_brightness = props.max_brightness;
292 props.brightness = pdata->initial_brightness;
294 bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
295 &lp855x_bl_ops, &props);
304 static ssize_t lp855x_get_chip_id(struct device *dev,
305 struct device_attribute *attr, char *buf)
307 struct lp855x *lp = dev_get_drvdata(dev);
309 return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
312 static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
313 struct device_attribute *attr, char *buf)
315 struct lp855x *lp = dev_get_drvdata(dev);
316 char *strmode = NULL;
318 if (lp->mode == PWM_BASED)
319 strmode = "pwm based";
320 else if (lp->mode == REGISTER_BASED)
321 strmode = "register based";
323 return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
326 static DEVICE_ATTR(chip_id, S_IRUGO, lp855x_get_chip_id, NULL);
327 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp855x_get_bl_ctl_mode, NULL);
329 static struct attribute *lp855x_attributes[] = {
330 &dev_attr_chip_id.attr,
331 &dev_attr_bl_ctl_mode.attr,
335 static const struct attribute_group lp855x_attr_group = {
336 .attrs = lp855x_attributes,
340 static int lp855x_parse_dt(struct lp855x *lp)
342 struct device *dev = lp->dev;
343 struct device_node *node = dev->of_node;
344 struct lp855x_platform_data *pdata;
348 dev_err(dev, "no platform data\n");
352 pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
356 of_property_read_string(node, "bl-name", &pdata->name);
357 of_property_read_u8(node, "dev-ctrl", &pdata->device_control);
358 of_property_read_u8(node, "init-brt", &pdata->initial_brightness);
359 of_property_read_u32(node, "pwm-period", &pdata->period_ns);
361 /* Fill ROM platform data if defined */
362 rom_length = of_get_child_count(node);
363 if (rom_length > 0) {
364 struct lp855x_rom_data *rom;
365 struct device_node *child;
368 rom = devm_kzalloc(dev, sizeof(*rom) * rom_length, GFP_KERNEL);
372 for_each_child_of_node(node, child) {
373 of_property_read_u8(child, "rom-addr", &rom[i].addr);
374 of_property_read_u8(child, "rom-val", &rom[i].val);
378 pdata->size_program = rom_length;
379 pdata->rom_data = &rom[0];
387 static int lp855x_parse_dt(struct lp855x *lp)
393 static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
398 if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
401 lp = devm_kzalloc(&cl->dev, sizeof(struct lp855x), GFP_KERNEL);
407 lp->chipname = id->name;
408 lp->chip_id = id->driver_data;
409 lp->pdata = dev_get_platdata(&cl->dev);
412 ret = lp855x_parse_dt(lp);
417 if (lp->pdata->period_ns > 0)
418 lp->mode = PWM_BASED;
420 lp->mode = REGISTER_BASED;
422 lp->supply = devm_regulator_get(lp->dev, "power");
423 if (IS_ERR(lp->supply)) {
424 if (PTR_ERR(lp->supply) == -EPROBE_DEFER)
425 return -EPROBE_DEFER;
430 ret = regulator_enable(lp->supply);
432 dev_err(&cl->dev, "failed to enable supply: %d\n", ret);
437 i2c_set_clientdata(cl, lp);
439 ret = lp855x_configure(lp);
441 dev_err(lp->dev, "device config err: %d", ret);
445 ret = lp855x_backlight_register(lp);
448 "failed to register backlight. err: %d\n", ret);
452 ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
454 dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
458 backlight_update_status(lp->bl);
462 static int lp855x_remove(struct i2c_client *cl)
464 struct lp855x *lp = i2c_get_clientdata(cl);
466 lp->bl->props.brightness = 0;
467 backlight_update_status(lp->bl);
469 regulator_disable(lp->supply);
470 sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
475 static const struct of_device_id lp855x_dt_ids[] = {
476 { .compatible = "ti,lp8550", },
477 { .compatible = "ti,lp8551", },
478 { .compatible = "ti,lp8552", },
479 { .compatible = "ti,lp8553", },
480 { .compatible = "ti,lp8555", },
481 { .compatible = "ti,lp8556", },
482 { .compatible = "ti,lp8557", },
485 MODULE_DEVICE_TABLE(of, lp855x_dt_ids);
487 static const struct i2c_device_id lp855x_ids[] = {
497 MODULE_DEVICE_TABLE(i2c, lp855x_ids);
499 static struct i2c_driver lp855x_driver = {
502 .of_match_table = of_match_ptr(lp855x_dt_ids),
504 .probe = lp855x_probe,
505 .remove = lp855x_remove,
506 .id_table = lp855x_ids,
509 module_i2c_driver(lp855x_driver);
511 MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
512 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
513 MODULE_LICENSE("GPL");