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// SPDX-License-Identifier: GPL-2.0
/*
* LED driver for Analog Devices LTC3208 Multi-Display Driver
*
* Copyright 2026 Analog Devices Inc.
*
* Author: Jan Carlo Roleda <jancarlo.roleda@analog.com>
*
*/
#include <linux/bitfield.h>
#include <linux/bitmap.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/leds.h>
#include <linux/module.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/types.h>
/* Registers */
#define LTC3208_REG_A_GRNRED_CURRENT 0x1 /* Green and Red current DAC */
#define LTC3208_REG_B_AUXBLU_CURRENT 0x2 /* AUX and Blue current DAC */
#define LTC3208_REG_C_MAIN_CURRENT 0x3 /* Main current DAC */
#define LTC3208_REG_D_SUB_CURRENT 0x4 /* Sub current DAC */
#define LTC3208_REG_E_AUX_SELECT 0x5 /* AUX DAC Select */
#define LTC3208_AUX1_MASK GENMASK(1, 0)
#define LTC3208_AUX2_MASK GENMASK(3, 2)
#define LTC3208_AUX3_MASK GENMASK(5, 4)
#define LTC3208_AUX4_MASK GENMASK(7, 6)
#define LTC3208_REG_F_CAM_CURRENT 0x6 /* CAM (High and Low) current DAC */
#define LTC3208_REG_G_OPT 0x7 /* Device Options */
#define LTC3208_OPT_CPO_MASK GENMASK(7, 6)
#define LTC3208_OPT_DIS_RGBDROP BIT(3)
#define LTC3208_OPT_DIS_CAMHILO BIT(2)
#define LTC3208_OPT_EN_RGBS BIT(1)
#define LTC3208_MAX_BRIGHTNESS_4BIT 0xF
#define LTC3208_MAX_BRIGHTNESS_8BIT 0xFF
#define LTC3208_NUM_AUX_LEDS 4 /* Number of configurable aux channels */
#define LTC3208_NUM_REGS 7 /* Number of available registers to access */
enum ltc3208_aux_channel {
LTC3208_AUX_CHAN_AUX = 0,
LTC3208_AUX_CHAN_MAIN,
LTC3208_AUX_CHAN_SUB,
LTC3208_AUX_CHAN_CAM
};
enum ltc3208_channel {
LTC3208_CHAN_MAIN = 0,
LTC3208_CHAN_SUB,
LTC3208_CHAN_AUX,
LTC3208_CHAN_CAML,
LTC3208_CHAN_CAMH,
LTC3208_CHAN_RED,
LTC3208_CHAN_BLUE,
LTC3208_CHAN_GREEN,
LTC3208_CHAN_N_COUNT,
};
static const char *const ltc3208_dt_aux_channels[] = {
"adi,aux1-channel",
"adi,aux2-channel",
"adi,aux3-channel",
"adi,aux4-channel"
};
static const char *const ltc3208_aux_opt[] = { "aux", "main", "sub", "cam" };
struct ltc3208_led {
struct led_classdev cdev;
struct regmap_field *rfield;
};
static const struct reg_default ltc3208_reg_defaults[] = {
{ LTC3208_REG_A_GRNRED_CURRENT, 0 },
{ LTC3208_REG_B_AUXBLU_CURRENT, 0 },
{ LTC3208_REG_C_MAIN_CURRENT, 0 },
{ LTC3208_REG_D_SUB_CURRENT, 0 },
{ LTC3208_REG_E_AUX_SELECT, 0 },
{ LTC3208_REG_F_CAM_CURRENT, 0 },
{ LTC3208_REG_G_OPT, 0 }
};
static const struct regmap_config ltc3208_regmap_cfg = {
.reg_bits = 8,
.val_bits = 8,
.max_register = LTC3208_REG_G_OPT,
.cache_type = REGCACHE_FLAT_S,
.reg_defaults = ltc3208_reg_defaults,
.num_reg_defaults = LTC3208_NUM_REGS,
};
static const struct reg_field ltc3208_led_reg_field[LTC3208_CHAN_N_COUNT] = {
[LTC3208_CHAN_MAIN] = REG_FIELD(LTC3208_REG_C_MAIN_CURRENT, 0, 7),
[LTC3208_CHAN_SUB] = REG_FIELD(LTC3208_REG_D_SUB_CURRENT, 0, 7),
[LTC3208_CHAN_BLUE] = REG_FIELD(LTC3208_REG_B_AUXBLU_CURRENT, 0, 3),
[LTC3208_CHAN_AUX] = REG_FIELD(LTC3208_REG_B_AUXBLU_CURRENT, 4, 7),
[LTC3208_CHAN_CAML] = REG_FIELD(LTC3208_REG_F_CAM_CURRENT, 0, 3),
[LTC3208_CHAN_CAMH] = REG_FIELD(LTC3208_REG_F_CAM_CURRENT, 4, 7),
[LTC3208_CHAN_RED] = REG_FIELD(LTC3208_REG_A_GRNRED_CURRENT, 0, 3),
[LTC3208_CHAN_GREEN] = REG_FIELD(LTC3208_REG_A_GRNRED_CURRENT, 4, 7),
};
static int ltc3208_led_set_brightness(struct led_classdev *led_cdev, enum led_brightness brightness)
{
struct ltc3208_led *led = container_of(led_cdev, struct ltc3208_led, cdev);
u8 current_level = brightness;
return regmap_field_write(led->rfield, current_level);
}
static int ltc3208_probe(struct i2c_client *client)
{
enum ltc3208_aux_channel aux_channels[LTC3208_NUM_AUX_LEDS];
DECLARE_BITMAP(registered_chans, LTC3208_CHAN_N_COUNT) = { };
struct regmap *regmap;
bool disable_rgb_aux4_dropout_signal;
bool disable_camhl_pin;
bool set_sub_control_pin;
int ret;
u8 dev_options;
regmap = devm_regmap_init_i2c(client, <c3208_regmap_cfg);
if (IS_ERR(regmap))
return dev_err_probe(&client->dev, PTR_ERR(regmap), "Failed to initialize regmap");
regcache_mark_dirty(regmap);
ret = regcache_sync(regmap);
if (ret)
return dev_err_probe(&client->dev, ret, "Failed to sync register cache");
disable_camhl_pin = device_property_read_bool(&client->dev, "adi,disable-camhl-pin");
set_sub_control_pin = device_property_read_bool(&client->dev, "adi,cfg-enrgbs-pin");
disable_rgb_aux4_dropout_signal =
device_property_read_bool(&client->dev, "adi,disable-rgb-aux4-dropout");
dev_options = FIELD_PREP(LTC3208_OPT_EN_RGBS, set_sub_control_pin) |
FIELD_PREP(LTC3208_OPT_DIS_CAMHILO, disable_camhl_pin) |
FIELD_PREP(LTC3208_OPT_CPO_MASK, 0) |
FIELD_PREP(LTC3208_OPT_DIS_RGBDROP, disable_rgb_aux4_dropout_signal);
ret = regmap_write(regmap, LTC3208_REG_G_OPT, dev_options);
if (ret)
return dev_err_probe(&client->dev, ret, "Failed to set device options register");
/* Initialize AUX channel configurations */
for (int i = 0; i < LTC3208_NUM_AUX_LEDS; i++) {
/* Default value (AUX) if property is not present in DT */
if (!device_property_present(&client->dev, ltc3208_dt_aux_channels[i])) {
aux_channels[i] = LTC3208_AUX_CHAN_AUX;
continue;
}
ret = device_property_match_property_string(&client->dev,
ltc3208_dt_aux_channels[i],
ltc3208_aux_opt, LTC3208_NUM_AUX_LEDS);
if (ret < 0)
return dev_err_probe(&client->dev, ret, "Error reading AUX Channel %d", i);
aux_channels[i] = ret;
}
dev_options = FIELD_PREP(LTC3208_AUX1_MASK, aux_channels[0]) |
FIELD_PREP(LTC3208_AUX2_MASK, aux_channels[1]) |
FIELD_PREP(LTC3208_AUX3_MASK, aux_channels[2]) |
FIELD_PREP(LTC3208_AUX4_MASK, aux_channels[3]);
ret = regmap_write(regmap, LTC3208_REG_E_AUX_SELECT, dev_options);
if (ret)
return dev_err_probe(&client->dev, ret, "Error writing to aux channel register");
device_for_each_child_node_scoped(&client->dev, child) {
struct ltc3208_led *led;
struct led_init_data init_data = { };
u32 chan;
ret = fwnode_property_read_u32(child, "reg", &chan);
if (ret)
return dev_err_probe(&client->dev, ret,
"Failed to get register value of LED");
if (chan >= LTC3208_CHAN_N_COUNT)
return dev_err_probe(&client->dev, -EINVAL, "%u is an invalid LED ID",
chan);
if (test_and_set_bit(chan, registered_chans))
return dev_err_probe(&client->dev, -EINVAL, "%u is already registered",
chan);
led = devm_kzalloc(&client->dev, sizeof(*led), GFP_KERNEL);
if (!led)
return -ENOMEM;
led->rfield = devm_regmap_field_alloc(&client->dev, regmap,
ltc3208_led_reg_field[chan]);
if (IS_ERR(led->rfield))
return dev_err_probe(&client->dev, PTR_ERR(led->rfield),
"Cannot allocate regmap field");
led->cdev.brightness_set_blocking = ltc3208_led_set_brightness;
led->cdev.max_brightness = LTC3208_MAX_BRIGHTNESS_4BIT;
if (chan == LTC3208_CHAN_MAIN || chan == LTC3208_CHAN_SUB)
led->cdev.max_brightness = LTC3208_MAX_BRIGHTNESS_8BIT;
init_data.fwnode = child;
ret = devm_led_classdev_register_ext(&client->dev, &led->cdev, &init_data);
if (ret)
return dev_err_probe(&client->dev, ret, "Failed to register LED %u", chan);
}
return 0;
}
static const struct of_device_id ltc3208_match_table[] = {
{ .compatible = "adi,ltc3208" },
{ }
};
MODULE_DEVICE_TABLE(of, ltc3208_match_table);
static struct i2c_driver ltc3208_driver = {
.driver = {
.name = "ltc3208",
.of_match_table = ltc3208_match_table,
},
.probe = ltc3208_probe,
};
module_i2c_driver(ltc3208_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jan Carlo Roleda <jancarlo.roleda@analog.com>");
MODULE_DESCRIPTION("LTC3208 LED Driver");
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