1 // SPDX-License-Identifier: GPL-2.0-only
3 * TI LP855x Backlight Driver
5 * Copyright (C) 2011 Texas Instruments
8 #include <linux/acpi.h>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/i2c.h>
12 #include <linux/backlight.h>
13 #include <linux/delay.h>
14 #include <linux/err.h>
16 #include <linux/platform_data/lp855x.h>
17 #include <linux/pwm.h>
18 #include <linux/regulator/consumer.h>
20 /* LP8550/1/2/3/6 Registers */
21 #define LP855X_BRIGHTNESS_CTRL 0x00
22 #define LP855X_DEVICE_CTRL 0x01
23 #define LP855X_EEPROM_START 0xA0
24 #define LP855X_EEPROM_END 0xA7
25 #define LP8556_EPROM_START 0xA0
26 #define LP8556_EPROM_END 0xAF
28 /* LP8555/7 Registers */
29 #define LP8557_BL_CMD 0x00
30 #define LP8557_BL_MASK 0x01
31 #define LP8557_BL_ON 0x01
32 #define LP8557_BL_OFF 0x00
33 #define LP8557_BRIGHTNESS_CTRL 0x04
34 #define LP8557_CONFIG 0x10
35 #define LP8555_EPROM_START 0x10
36 #define LP8555_EPROM_END 0x7A
37 #define LP8557_EPROM_START 0x10
38 #define LP8557_EPROM_END 0x1E
40 #define DEFAULT_BL_NAME "lcd-backlight"
41 #define MAX_BRIGHTNESS 255
43 enum lp855x_brightness_ctrl_mode {
51 * struct lp855x_device_config
52 * @pre_init_device: init device function call before updating the brightness
53 * @reg_brightness: register address for brigthenss control
54 * @reg_devicectrl: register address for device control
55 * @post_init_device: late init device function call
57 struct lp855x_device_config {
58 int (*pre_init_device)(struct lp855x *);
61 int (*post_init_device)(struct lp855x *);
66 enum lp855x_chip_id chip_id;
67 enum lp855x_brightness_ctrl_mode mode;
68 struct lp855x_device_config *cfg;
69 struct i2c_client *client;
70 struct backlight_device *bl;
72 struct lp855x_platform_data *pdata;
73 struct pwm_device *pwm;
74 struct regulator *supply; /* regulator for VDD input */
75 struct regulator *enable; /* regulator for EN/VDDIO input */
78 static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
80 return i2c_smbus_write_byte_data(lp->client, reg, data);
83 static int lp855x_update_bit(struct lp855x *lp, u8 reg, u8 mask, u8 data)
88 ret = i2c_smbus_read_byte_data(lp->client, reg);
90 dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
98 return lp855x_write_byte(lp, reg, tmp);
101 static bool lp855x_is_valid_rom_area(struct lp855x *lp, u8 addr)
105 switch (lp->chip_id) {
110 start = LP855X_EEPROM_START;
111 end = LP855X_EEPROM_END;
114 start = LP8556_EPROM_START;
115 end = LP8556_EPROM_END;
118 start = LP8555_EPROM_START;
119 end = LP8555_EPROM_END;
122 start = LP8557_EPROM_START;
123 end = LP8557_EPROM_END;
129 return addr >= start && addr <= end;
132 static int lp8557_bl_off(struct lp855x *lp)
134 /* BL_ON = 0 before updating EPROM settings */
135 return lp855x_update_bit(lp, LP8557_BL_CMD, LP8557_BL_MASK,
139 static int lp8557_bl_on(struct lp855x *lp)
141 /* BL_ON = 1 after updating EPROM settings */
142 return lp855x_update_bit(lp, LP8557_BL_CMD, LP8557_BL_MASK,
146 static struct lp855x_device_config lp855x_dev_cfg = {
147 .reg_brightness = LP855X_BRIGHTNESS_CTRL,
148 .reg_devicectrl = LP855X_DEVICE_CTRL,
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,
159 * Device specific configuration flow
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)
168 static int lp855x_configure(struct lp855x *lp)
172 struct lp855x_platform_data *pd = lp->pdata;
174 if (lp->cfg->pre_init_device) {
175 ret = lp->cfg->pre_init_device(lp);
177 dev_err(lp->dev, "pre init device err: %d\n", ret);
182 val = pd->initial_brightness;
183 ret = lp855x_write_byte(lp, lp->cfg->reg_brightness, val);
187 val = pd->device_control;
188 ret = lp855x_write_byte(lp, lp->cfg->reg_devicectrl, val);
192 if (pd->size_program > 0) {
193 for (i = 0; i < pd->size_program; i++) {
194 addr = pd->rom_data[i].addr;
195 val = pd->rom_data[i].val;
196 if (!lp855x_is_valid_rom_area(lp, addr))
199 ret = lp855x_write_byte(lp, addr, val);
205 if (lp->cfg->post_init_device) {
206 ret = lp->cfg->post_init_device(lp);
208 dev_err(lp->dev, "post init device err: %d\n", ret);
219 static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br)
221 struct pwm_device *pwm;
222 struct pwm_state state;
224 /* request pwm device with the consumer name */
226 pwm = devm_pwm_get(lp->dev, lp->chipname);
232 pwm_init_state(lp->pwm, &state);
234 pwm_get_state(lp->pwm, &state);
237 state.period = lp->pdata->period_ns;
238 state.duty_cycle = div_u64(br * state.period, max_br);
239 state.enabled = state.duty_cycle;
241 pwm_apply_state(lp->pwm, &state);
244 static int lp855x_bl_update_status(struct backlight_device *bl)
246 struct lp855x *lp = bl_get_data(bl);
247 int brightness = bl->props.brightness;
249 if (bl->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
252 if (lp->mode == PWM_BASED)
253 lp855x_pwm_ctrl(lp, brightness, bl->props.max_brightness);
254 else if (lp->mode == REGISTER_BASED)
255 lp855x_write_byte(lp, lp->cfg->reg_brightness, (u8)brightness);
260 static const struct backlight_ops lp855x_bl_ops = {
261 .options = BL_CORE_SUSPENDRESUME,
262 .update_status = lp855x_bl_update_status,
265 static int lp855x_backlight_register(struct lp855x *lp)
267 struct backlight_device *bl;
268 struct backlight_properties props;
269 struct lp855x_platform_data *pdata = lp->pdata;
270 const char *name = pdata->name ? : DEFAULT_BL_NAME;
272 memset(&props, 0, sizeof(props));
273 props.type = BACKLIGHT_PLATFORM;
274 props.max_brightness = MAX_BRIGHTNESS;
276 if (pdata->initial_brightness > props.max_brightness)
277 pdata->initial_brightness = props.max_brightness;
279 props.brightness = pdata->initial_brightness;
281 bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
282 &lp855x_bl_ops, &props);
291 static ssize_t lp855x_get_chip_id(struct device *dev,
292 struct device_attribute *attr, char *buf)
294 struct lp855x *lp = dev_get_drvdata(dev);
296 return scnprintf(buf, PAGE_SIZE, "%s\n", lp->chipname);
299 static ssize_t lp855x_get_bl_ctl_mode(struct device *dev,
300 struct device_attribute *attr, char *buf)
302 struct lp855x *lp = dev_get_drvdata(dev);
303 char *strmode = NULL;
305 if (lp->mode == PWM_BASED)
306 strmode = "pwm based";
307 else if (lp->mode == REGISTER_BASED)
308 strmode = "register based";
310 return scnprintf(buf, PAGE_SIZE, "%s\n", strmode);
313 static DEVICE_ATTR(chip_id, S_IRUGO, lp855x_get_chip_id, NULL);
314 static DEVICE_ATTR(bl_ctl_mode, S_IRUGO, lp855x_get_bl_ctl_mode, NULL);
316 static struct attribute *lp855x_attributes[] = {
317 &dev_attr_chip_id.attr,
318 &dev_attr_bl_ctl_mode.attr,
322 static const struct attribute_group lp855x_attr_group = {
323 .attrs = lp855x_attributes,
327 static int lp855x_parse_dt(struct lp855x *lp)
329 struct device *dev = lp->dev;
330 struct device_node *node = dev->of_node;
331 struct lp855x_platform_data *pdata = lp->pdata;
335 dev_err(dev, "no platform data\n");
339 of_property_read_string(node, "bl-name", &pdata->name);
340 of_property_read_u8(node, "dev-ctrl", &pdata->device_control);
341 of_property_read_u8(node, "init-brt", &pdata->initial_brightness);
342 of_property_read_u32(node, "pwm-period", &pdata->period_ns);
344 /* Fill ROM platform data if defined */
345 rom_length = of_get_child_count(node);
346 if (rom_length > 0) {
347 struct lp855x_rom_data *rom;
348 struct device_node *child;
351 rom = devm_kcalloc(dev, rom_length, sizeof(*rom), GFP_KERNEL);
355 for_each_child_of_node(node, child) {
356 of_property_read_u8(child, "rom-addr", &rom[i].addr);
357 of_property_read_u8(child, "rom-val", &rom[i].val);
361 pdata->size_program = rom_length;
362 pdata->rom_data = &rom[0];
368 static int lp855x_parse_dt(struct lp855x *lp)
374 static int lp855x_parse_acpi(struct lp855x *lp)
379 * On ACPI the device has already been initialized by the firmware
380 * and is in register mode, so we can read back the settings from
383 ret = i2c_smbus_read_byte_data(lp->client, lp->cfg->reg_brightness);
387 lp->pdata->initial_brightness = ret;
389 ret = i2c_smbus_read_byte_data(lp->client, lp->cfg->reg_devicectrl);
393 lp->pdata->device_control = ret;
397 static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
399 const struct acpi_device_id *acpi_id = NULL;
400 struct device *dev = &cl->dev;
404 if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
407 lp = devm_kzalloc(dev, sizeof(struct lp855x), GFP_KERNEL);
413 lp->pdata = dev_get_platdata(dev);
416 lp->chipname = id->name;
417 lp->chip_id = id->driver_data;
419 acpi_id = acpi_match_device(dev->driver->acpi_match_table, dev);
423 lp->chipname = acpi_id->id;
424 lp->chip_id = acpi_id->driver_data;
427 switch (lp->chip_id) {
433 lp->cfg = &lp855x_dev_cfg;
437 lp->cfg = &lp8557_dev_cfg;
444 lp->pdata = devm_kzalloc(dev, sizeof(*lp->pdata), GFP_KERNEL);
449 ret = lp855x_parse_dt(lp);
453 ret = lp855x_parse_acpi(lp);
459 if (lp->pdata->period_ns > 0)
460 lp->mode = PWM_BASED;
462 lp->mode = REGISTER_BASED;
464 lp->supply = devm_regulator_get(dev, "power");
465 if (IS_ERR(lp->supply)) {
466 if (PTR_ERR(lp->supply) == -EPROBE_DEFER)
467 return -EPROBE_DEFER;
471 lp->enable = devm_regulator_get_optional(dev, "enable");
472 if (IS_ERR(lp->enable)) {
473 ret = PTR_ERR(lp->enable);
474 if (ret == -ENODEV) {
477 return dev_err_probe(dev, ret, "getting enable regulator\n");
482 ret = regulator_enable(lp->supply);
484 dev_err(dev, "failed to enable supply: %d\n", ret);
490 ret = regulator_enable(lp->enable);
492 dev_err(dev, "failed to enable vddio: %d\n", ret);
497 * LP8555 datasheet says t_RESPONSE (time between VDDIO and
500 usleep_range(1000, 2000);
503 i2c_set_clientdata(cl, lp);
505 ret = lp855x_configure(lp);
507 dev_err(dev, "device config err: %d", ret);
511 ret = lp855x_backlight_register(lp);
513 dev_err(dev, "failed to register backlight. err: %d\n", ret);
517 ret = sysfs_create_group(&dev->kobj, &lp855x_attr_group);
519 dev_err(dev, "failed to register sysfs. err: %d\n", ret);
523 backlight_update_status(lp->bl);
529 regulator_disable(lp->enable);
532 regulator_disable(lp->supply);
537 static int lp855x_remove(struct i2c_client *cl)
539 struct lp855x *lp = i2c_get_clientdata(cl);
541 lp->bl->props.brightness = 0;
542 backlight_update_status(lp->bl);
544 regulator_disable(lp->enable);
546 regulator_disable(lp->supply);
547 sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);
552 static const struct of_device_id lp855x_dt_ids[] = {
553 { .compatible = "ti,lp8550", },
554 { .compatible = "ti,lp8551", },
555 { .compatible = "ti,lp8552", },
556 { .compatible = "ti,lp8553", },
557 { .compatible = "ti,lp8555", },
558 { .compatible = "ti,lp8556", },
559 { .compatible = "ti,lp8557", },
562 MODULE_DEVICE_TABLE(of, lp855x_dt_ids);
564 static const struct i2c_device_id lp855x_ids[] = {
574 MODULE_DEVICE_TABLE(i2c, lp855x_ids);
577 static const struct acpi_device_id lp855x_acpi_match[] = {
578 /* Xiaomi specific HID used for the LP8556 on the Mi Pad 2 */
579 { "XMCC0001", LP8556 },
582 MODULE_DEVICE_TABLE(acpi, lp855x_acpi_match);
585 static struct i2c_driver lp855x_driver = {
588 .of_match_table = of_match_ptr(lp855x_dt_ids),
589 .acpi_match_table = ACPI_PTR(lp855x_acpi_match),
591 .probe = lp855x_probe,
592 .remove = lp855x_remove,
593 .id_table = lp855x_ids,
596 module_i2c_driver(lp855x_driver);
598 MODULE_DESCRIPTION("Texas Instruments LP855x Backlight driver");
599 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
600 MODULE_LICENSE("GPL");