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>
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
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
41 #define DEFAULT_BL_NAME "lcd-backlight"
42 #define MAX_BRIGHTNESS 255
44 enum lp855x_brightness_ctrl_mode {
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
58 struct lp855x_device_config {
59 int (*pre_init_device)(struct lp855x *);
62 int (*post_init_device)(struct lp855x *);
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;
73 struct lp855x_platform_data *pdata;
74 struct pwm_device *pwm;
77 static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
79 return i2c_smbus_write_byte_data(lp->client, reg, data);
82 static int lp855x_update_bit(struct lp855x *lp, u8 reg, u8 mask, u8 data)
87 ret = i2c_smbus_read_byte_data(lp->client, reg);
89 dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
97 return lp855x_write_byte(lp, reg, tmp);
100 static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
104 switch (lp->chip_id) {
109 start = LP855X_EEPROM_START;
110 end = LP855X_EEPROM_END;
113 start = LP8556_EPROM_START;
114 end = LP8556_EPROM_END;
117 start = LP8555_EPROM_START;
118 end = LP8555_EPROM_END;
121 start = LP8557_EPROM_START;
122 end = LP8557_EPROM_END;
128 return addr >= start && addr <= end;
131 static int lp8557_bl_off(struct lp855x *lp)
133 /* BL_ON = 0 before updating EPROM settings */
134 return lp855x_update_bit(lp, LP8557_BL_CMD, LP8557_BL_MASK,
138 static int lp8557_bl_on(struct lp855x *lp)
140 /* BL_ON = 1 after updating EPROM settings */
141 return lp855x_update_bit(lp, LP8557_BL_CMD, LP8557_BL_MASK,
145 static struct lp855x_device_config lp855x_dev_cfg = {
146 .reg_brightness = LP855X_BRIGHTNESS_CTRL,
147 .reg_devicectrl = LP855X_DEVICE_CTRL,
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,
158 * Device specific configuration flow
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)
167 static int lp855x_configure(struct lp855x *lp)
171 struct lp855x_platform_data *pd = lp->pdata;
173 switch (lp->chip_id) {
179 lp->cfg = &lp855x_dev_cfg;
183 lp->cfg = &lp8557_dev_cfg;
189 if (lp->cfg->pre_init_device) {
190 ret = lp->cfg->pre_init_device(lp);
192 dev_err(lp->dev, "pre init device err: %d\n", ret);
197 val = pd->initial_brightness;
198 ret = lp855x_write_byte(lp, lp->cfg->reg_brightness, val);
202 val = pd->device_control;
203 ret = lp855x_write_byte(lp, lp->cfg->reg_devicectrl, val);
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))
214 ret = lp855x_write_byte(lp, addr, val);
220 if (lp->cfg->post_init_device) {
221 ret = lp->cfg->post_init_device(lp);
223 dev_err(lp->dev, "post init device err: %d\n", ret);
234 static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
236 unsigned int period = lp->pdata->period_ns;
237 unsigned int duty = br * period / max_br;
238 struct pwm_device *pwm;
240 /* request pwm device with the consumer name */
242 pwm = devm_pwm_get(lp->dev, lp->chipname);
249 pwm_config(lp->pwm, duty, period);
253 pwm_disable(lp->pwm);
256 static int lp855x_bl_update_status(struct backlight_device *bl)
258 struct lp855x *lp = bl_get_data(bl);
260 if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
261 bl->props.brightness = 0;
263 if (lp->mode == PWM_BASED) {
264 int br = bl->props.brightness;
265 int max_br = bl->props.max_brightness;
267 lp855x_pwm_ctrl(lp, br, max_br);
269 } else if (lp->mode == REGISTER_BASED) {
270 u8 val = bl->props.brightness;
272 lp855x_write_byte(lp, lp->cfg->reg_brightness, val);
278 static const struct backlight_ops lp855x_bl_ops = {
279 .options = BL_CORE_SUSPENDRESUME,
280 .update_status = lp855x_bl_update_status,
283 static int lp855x_backlight_register(struct lp855x *lp)
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;
290 props.type = BACKLIGHT_PLATFORM;
291 props.max_brightness = MAX_BRIGHTNESS;
293 if (pdata->initial_brightness > props.max_brightness)
294 pdata->initial_brightness = props.max_brightness;
296 props.brightness = pdata->initial_brightness;
298 bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
299 &lp855x_bl_ops, &props);
308 static ssize_t lp855x_get_chip_id(struct device *dev,
309 struct device_attribute *attr, char *buf)
311 struct lp855x *lp = dev_get_drvdata(dev);
313 return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
316 static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
317 struct device_attribute *attr, char *buf)
319 struct lp855x *lp = dev_get_drvdata(dev);
320 char *strmode = NULL;
322 if (lp->mode == PWM_BASED)
323 strmode = "pwm based";
324 else if (lp->mode == REGISTER_BASED)
325 strmode = "register based";
327 return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
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);
333 static struct attribute *lp855x_attributes[] = {
334 &dev_attr_chip_id.attr,
335 &dev_attr_bl_ctl_mode.attr,
339 static const struct attribute_group lp855x_attr_group = {
340 .attrs = lp855x_attributes,
344 static int lp855x_parse_dt(struct device *dev, struct device_node *node)
346 struct lp855x_platform_data *pdata;
350 dev_err(dev, "no platform data\n");
354 pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
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);
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;
370 rom = devm_kzalloc(dev, sizeof(*rom) * rom_length, GFP_KERNEL);
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);
380 pdata->size_program = rom_length;
381 pdata->rom_data = &rom[0];
384 dev->platform_data = pdata;
389 static int lp855x_parse_dt(struct device *dev, struct device_node *node)
395 static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
398 struct lp855x_platform_data *pdata = dev_get_platdata(&cl->dev);
399 struct device_node *node = cl->dev.of_node;
403 ret = lp855x_parse_dt(&cl->dev, node);
407 pdata = dev_get_platdata(&cl->dev);
410 if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
413 lp = devm_kzalloc(&cl->dev, sizeof(struct lp855x), GFP_KERNEL);
417 if (pdata->period_ns > 0)
418 lp->mode = PWM_BASED;
420 lp->mode = REGISTER_BASED;
425 lp->chipname = id->name;
426 lp->chip_id = id->driver_data;
427 i2c_set_clientdata(cl, lp);
429 ret = lp855x_configure(lp);
431 dev_err(lp->dev, "device config err: %d", ret);
435 ret = lp855x_backlight_register(lp);
438 "failed to register backlight. err: %d\n", ret);
442 ret = sysfs_create_group(&lp->dev->kobj, &lp855x_attr_group);
444 dev_err(lp->dev, "failed to register sysfs. err: %d\n", ret);
448 backlight_update_status(lp->bl);
452 static int lp855x_remove(struct i2c_client *cl)
454 struct lp855x *lp = i2c_get_clientdata(cl);
456 lp->bl->props.brightness = 0;
457 backlight_update_status(lp->bl);
458 sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
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", },
473 MODULE_DEVICE_TABLE(of, lp855x_dt_ids);
475 static const struct i2c_device_id lp855x_ids[] = {
485 MODULE_DEVICE_TABLE(i2c, lp855x_ids);
487 static struct i2c_driver lp855x_driver = {
490 .of_match_table = of_match_ptr(lp855x_dt_ids),
492 .probe = lp855x_probe,
493 .remove = lp855x_remove,
494 .id_table = lp855x_ids,
497 module_i2c_driver(lp855x_driver);
499 MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
500 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
501 MODULE_LICENSE("GPL");