[PATCH v6 2/2] leds: ltc3220: Add Support for LTC3220 18 channel LED Driver

Edelweise Escala
2026-04-17T09:43:00Z

Add driver for the LTC3220 18-channel LED driver
with I2C interface, individual brightness control, and hardware-assisted
blink/gradation features.

Signed-off-by: Edelweise Escala <edelweise.escala@analog.com>
---
MAINTAINERS | 1 +
drivers/leds/Kconfig | 12 ++
drivers/leds/Makefile | 1 +
drivers/leds/leds-ltc3220.c | 418 ++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 432 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 5c10cc3e3022..7467537938bf 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14961,6 +14961,7 @@ L: linux-leds@vger.kernel.org
S: Maintained
W: https://ez.analog.com/linux-software-drivers
F: Documentation/devicetree/bindings/leds/adi,ltc3220.yaml
+F: drivers/leds/leds-ltc3220.c

LTC4282 HARDWARE MONITOR DRIVER
M: Nuno Sa <nuno.sa@analog.com>
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 597d7a79c988..f00cdc11c978 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -1001,6 +1001,18 @@ config LEDS_ST1202
Say Y to enable support for LEDs connected to LED1202
LED driver chips accessed via the I2C bus.

+config LEDS_LTC3220
+ tristate "LED Driver for Analog Devices Inc. LTC3220"
+ depends on I2C && LEDS_CLASS
+ help
+ Say Y to enable support for the Analog Devices LTC3220
+ 18-channel LED controller with I2C interface.
+ The driver supports individual LED brightness control (64 steps),
+ hardware-assisted blinking and gradation effects.
+
+ To compile this driver as a module, choose M here: the module will
+ be called leds-ltc3220.
+
config LEDS_TPS6105X
tristate "LED support for TI TPS6105X"
depends on LEDS_CLASS
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 8fdb45d5b439..5301568d9e00 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -61,6 +61,7 @@ obj-$(CONFIG_LEDS_LP8788) += leds-lp8788.o
obj-$(CONFIG_LEDS_LP8860) += leds-lp8860.o
obj-$(CONFIG_LEDS_LP8864) += leds-lp8864.o
obj-$(CONFIG_LEDS_LT3593) += leds-lt3593.o
+obj-$(CONFIG_LEDS_LTC3220) += leds-ltc3220.o
obj-$(CONFIG_LEDS_MAX5970) += leds-max5970.o
obj-$(CONFIG_LEDS_MAX77650) += leds-max77650.o
obj-$(CONFIG_LEDS_MAX77705) += leds-max77705.o
diff --git a/drivers/leds/leds-ltc3220.c b/drivers/leds/leds-ltc3220.c
new file mode 100644
index 000000000000..5e1f994cc35b
--- /dev/null
+++ b/drivers/leds/leds-ltc3220.c
@@ -0,0 +1,418 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * LTC3220 18-Channel LED Driver
+ *
+ * Copyright 2026 Analog Devices Inc.
+ *
+ * Author: Edelweise Escala <edelweise.escala@analog.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/leds.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+/* LTC3220 Registers */
+#define LTC3220_COMMAND_REG 0x00
+#define LTC3220_QUICK_WRITE_MASK BIT(0)
+#define LTC3220_SHUTDOWN_MASK BIT(3)
+
+#define LTC3220_ULED_REG(x) (0x01 + (x))
+#define LTC3220_LED_CURRENT_MASK GENMASK(5, 0)
+#define LTC3220_LED_MODE_MASK GENMASK(7, 6)
+
+#define LTC3220_GRAD_BLINK_REG 0x13
+#define LTC3220_GRADATION_MASK GENMASK(2, 0)
+#define LTC3220_GRADATION_DIRECTION_MASK BIT(0)
+#define LTC3220_GRADATION_PERIOD_MASK GENMASK(2, 1)
+#define LTC3220_BLINK_MASK GENMASK(4, 3)
+
+#define LTC3220_NUM_LEDS 18
+
+#define LTC3220_GRADATION_START_VALUE 128
+#define LTC3220_GRADATION_RAMP_TIME_240MS 240
+#define LTC3220_GRADATION_RAMP_TIME_480MS 480
+
+#define LTC3220_BLINK_ON_156MS 156
+#define LTC3220_BLINK_ON_625MS 625
+#define LTC3220_BLINK_PERIOD_1250MS 1250
+#define LTC3220_BLINK_PERIOD_2500MS 2500
+
+#define LTC3220_BLINK_SHORT_ON_TIME BIT(0)
+#define LTC3220_BLINK_LONG_PERIOD BIT(1)
+
+enum ltc3220_blink_mode {
+ LTC3220_BLINK_MODE_625MS_1250MS,
+ LTC3220_BLINK_MODE_156MS_1250MS,
+ LTC3220_BLINK_MODE_625MS_2500MS,
+ LTC3220_BLINK_MODE_156MS_2500MS
+};
+
+enum ltc3220_gradation_mode {
+ LTC3220_GRADATION_MODE_DISABLED,
+ LTC3220_GRADATION_MODE_240MS_RAMP_TIME,
+ LTC3220_GRADATION_MODE_480MS_RAMP_TIME,
+ LTC3220_GRADATION_MODE_960MS_RAMP_TIME
+};
+
+static const struct regmap_config ltc3220_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .max_register = LTC3220_GRAD_BLINK_REG,
+};
+
+struct ltc3220_uled_cfg {
+ struct ltc3220_state *ltc3220_state;
+ struct led_classdev led_cdev;
+ u8 reg_value;
+ u8 led_index;
+};
+
+struct ltc3220_state {
+ struct ltc3220_uled_cfg uled_cfg[LTC3220_NUM_LEDS];
+ struct regmap *regmap;
+ bool is_aggregated;
+};
+
+static int ltc3220_shutdown(struct ltc3220_state *ltc3220_state)
+{
+ return regmap_update_bits(ltc3220_state->regmap, LTC3220_COMMAND_REG,
+ LTC3220_SHUTDOWN_MASK, LTC3220_SHUTDOWN_MASK);
+}
+
+static int ltc3220_resume_from_shutdown(struct ltc3220_state *ltc3220_state)
+{
+ return regmap_update_bits(ltc3220_state->regmap, LTC3220_COMMAND_REG,
+ LTC3220_SHUTDOWN_MASK, 0);
+}
+
+/*
+ * Set LED brightness and mode.
+ * The brightness value determines both the LED current and operating mode:
+ * 0-63: Normal mode - LED current from 0-63 (off to full brightness)
+ * 64-127: Blink mode - LED blinks with current level (brightness - 64)
+ * 128-191: Gradation mode - LED gradually changes brightness (brightness - 128)
+ * 192-255: GPO mode - LED operates as general purpose output (brightness - 192)
+ */
+static int ltc3220_set_led_data(struct led_classdev *led_cdev,
+ enum led_brightness brightness)
+{
+ struct ltc3220_state *ltc3220_state;
+ struct ltc3220_uled_cfg *uled_cfg;
+ int ret;
+ int i;
+
+ uled_cfg = container_of(led_cdev, struct ltc3220_uled_cfg, led_cdev);
+ ltc3220_state = uled_cfg->ltc3220_state;
+
+ ret = regmap_write(ltc3220_state->regmap, LTC3220_ULED_REG(uled_cfg->led_index),
+ brightness);
+ if (ret < 0)
+ return ret;
+
+ uled_cfg->reg_value = brightness;
+
+ /*
+ * When aggregated LED mode is enabled, writing to LED 1 updates all
+ * LEDs simultaneously via quick-write mode. Update cached values for
+ * all LEDs to reflect the synchronized state.
+ * See Documentation/devicetree/bindings/leds/adi,ltc3220.yaml for how
+ * to configure aggregated LED mode.
+ */
+ if (ltc3220_state->is_aggregated && uled_cfg->led_index == 0) {
+ for (i = 0; i < LTC3220_NUM_LEDS; i++)
+ ltc3220_state->uled_cfg[i].reg_value = brightness;
+ }
+
+ return 0;
+}
+
+static enum led_brightness ltc3220_get_led_data(struct led_classdev *led_cdev)
+{
+ struct ltc3220_uled_cfg *uled_cfg = container_of(led_cdev,
+ struct ltc3220_uled_cfg, led_cdev);
+
+ return uled_cfg->reg_value;
+}
+
+/*
+ * LTC3220 pattern support for hardware-assisted breathing/gradation.
+ * The hardware supports 3 gradation ramp time 240ms, 480ms, 960ms)
+ * and can ramp up or down.
+ *
+ * Pattern array interpretation:
+ * pattern[0].brightness = start brightness (0-63)
+ * pattern[0].delta_t = ramp time in milliseconds
+ * pattern[1].brightness = end brightness (0-63)
+ * pattern[1].delta_t = (optional, can be 0 or same as pattern[0].delta_t)
+ */
+static int ltc3220_pattern_set(struct led_classdev *led_cdev,
+ struct led_pattern *pattern,
+ u32 len, int repeat)
+{
+ struct ltc3220_uled_cfg *uled_cfg = container_of(led_cdev, struct ltc3220_uled_cfg,
+ led_cdev);
+ struct ltc3220_state *ltc3220_state = uled_cfg->ltc3220_state;
+ u8 gradation_period;
+ u8 start_brightness;
+ u8 end_brightness;
+ u8 reg_val;
+ bool is_increasing;
+ int ret;
+
+ if (len != 2)
+ return -EINVAL;
+
+ start_brightness = pattern[0].brightness & LTC3220_LED_CURRENT_MASK;
+ end_brightness = pattern[1].brightness & LTC3220_LED_CURRENT_MASK;
+
+ is_increasing = end_brightness > start_brightness;
+
+ if (pattern[0].delta_t == 0)
+ gradation_period = LTC3220_GRADATION_MODE_DISABLED;
+ else if (pattern[0].delta_t <= LTC3220_GRADATION_RAMP_TIME_240MS)
+ gradation_period = LTC3220_GRADATION_MODE_240MS_RAMP_TIME;
+ else if (pattern[0].delta_t <= LTC3220_GRADATION_RAMP_TIME_480MS)
+ gradation_period = LTC3220_GRADATION_MODE_480MS_RAMP_TIME;
+ else
+ gradation_period = LTC3220_GRADATION_MODE_960MS_RAMP_TIME;
+
+ reg_val = FIELD_PREP(LTC3220_GRADATION_PERIOD_MASK, gradation_period);
+ reg_val |= FIELD_PREP(LTC3220_GRADATION_DIRECTION_MASK, is_increasing);
+
+ ret = regmap_update_bits(ltc3220_state->regmap, LTC3220_GRAD_BLINK_REG,
+ LTC3220_GRADATION_MASK, reg_val);
+ if (ret < 0)
+ return ret;
+
+ ret = ltc3220_set_led_data(led_cdev, start_brightness);
+ if (ret < 0)
+ return ret;
+
+ return ltc3220_set_led_data(led_cdev, LTC3220_GRADATION_START_VALUE + end_brightness);
+}
+
+static int ltc3220_pattern_clear(struct led_classdev *led_cdev)
+{
+ struct ltc3220_uled_cfg *uled_cfg = container_of(led_cdev, struct ltc3220_uled_cfg,
+ led_cdev);
+ struct ltc3220_state *ltc3220_state = uled_cfg->ltc3220_state;
+
+ return regmap_update_bits(ltc3220_state->regmap, LTC3220_GRAD_BLINK_REG,
+ LTC3220_GRADATION_MASK, 0);
+}
+
+/*
+ * LTC3220 has a global blink configuration that affects all LEDs.
+ * This implementation allows per-LED blink requests, but the blink timing
+ * will be shared across all LEDs. The delay values are mapped to the
+ * hardware's discrete blink rates.
+ */
+static int ltc3220_blink_set(struct led_classdev *led_cdev,
+ unsigned long *delay_on,
+ unsigned long *delay_off)
+{
+ struct ltc3220_uled_cfg *uled_cfg = container_of(led_cdev, struct ltc3220_uled_cfg,
+ led_cdev);
+ struct ltc3220_state *ltc3220_state = uled_cfg->ltc3220_state;
+ u8 blink_mode = 0;
+
+ if (*delay_on <= LTC3220_BLINK_ON_156MS)
+ blink_mode = LTC3220_BLINK_SHORT_ON_TIME;
+
+ if (*delay_on + *delay_off > LTC3220_BLINK_PERIOD_1250MS)
+ blink_mode |= LTC3220_BLINK_LONG_PERIOD;
+
+ switch (blink_mode) {
+ case LTC3220_BLINK_MODE_625MS_1250MS:
+ *delay_on = LTC3220_BLINK_ON_625MS;
+ *delay_off = LTC3220_BLINK_PERIOD_1250MS - LTC3220_BLINK_ON_625MS;
+ break;
+ case LTC3220_BLINK_MODE_156MS_1250MS:
+ *delay_on = LTC3220_BLINK_ON_156MS;
+ *delay_off = LTC3220_BLINK_PERIOD_1250MS - LTC3220_BLINK_ON_156MS;
+ break;
+ case LTC3220_BLINK_MODE_625MS_2500MS:
+ *delay_on = LTC3220_BLINK_ON_625MS;
+ *delay_off = LTC3220_BLINK_PERIOD_2500MS - LTC3220_BLINK_ON_625MS;
+ break;
+ case LTC3220_BLINK_MODE_156MS_2500MS:
+ *delay_on = LTC3220_BLINK_ON_156MS;
+ *delay_off = LTC3220_BLINK_PERIOD_2500MS - LTC3220_BLINK_ON_156MS;
+ break;
+ }
+
+ return regmap_update_bits(ltc3220_state->regmap, LTC3220_GRAD_BLINK_REG,
+ LTC3220_BLINK_MASK, blink_mode);
+}
+
+static void ltc3220_reset_gpio_action(void *data)
+{
+ struct gpio_desc *reset_gpio = data;
+
+ gpiod_set_value_cansleep(reset_gpio, 1);
+}
+
+static int ltc3220_reset(struct ltc3220_state *ltc3220_state, struct i2c_client *client)
+{
+ struct gpio_desc *reset_gpio;
+ int ret;
+ int i;
+
+ reset_gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_HIGH);
+ if (IS_ERR(reset_gpio))
+ return dev_err_probe(&client->dev, PTR_ERR(reset_gpio), "Failed on reset GPIO\n");
+
+ if (reset_gpio) {
+ gpiod_set_value_cansleep(reset_gpio, 0);
+
+ return devm_add_action_or_reset(&client->dev, ltc3220_reset_gpio_action,
+ reset_gpio);
+ }
+
+ ret = regmap_write(ltc3220_state->regmap, LTC3220_COMMAND_REG, 0);
+ if (ret < 0)
+ return ret;
+
+ for (i = 0; i < LTC3220_NUM_LEDS; i++) {
+ ret = regmap_write(ltc3220_state->regmap, LTC3220_ULED_REG(i), 0);
+ if (ret < 0)
+ return ret;
+ }
+
+ return regmap_write(ltc3220_state->regmap, LTC3220_GRAD_BLINK_REG, 0);
+}
+
+static int ltc3220_suspend(struct device *dev)
+{
+ struct ltc3220_state *ltc3220_state = i2c_get_clientdata(to_i2c_client(dev));
+
+ return ltc3220_shutdown(ltc3220_state);
+}
+
+static int ltc3220_resume(struct device *dev)
+{
+ struct ltc3220_state *ltc3220_state = i2c_get_clientdata(to_i2c_client(dev));
+
+ return ltc3220_resume_from_shutdown(ltc3220_state);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(ltc3220_pm_ops, ltc3220_suspend, ltc3220_resume);
+
+static int ltc3220_probe(struct i2c_client *client)
+{
+ struct ltc3220_state *ltc3220_state;
+ bool aggregated_led_found = false;
+ int num_leds = 0;
+ u8 led_index = 0;
+ int ret;
+
+ ltc3220_state = devm_kzalloc(&client->dev, sizeof(*ltc3220_state), GFP_KERNEL);
+ if (!ltc3220_state)
+ return -ENOMEM;
+
+ ltc3220_state->regmap = devm_regmap_init_i2c(client, &ltc3220_regmap_config);
+ if (IS_ERR(ltc3220_state->regmap))
+ return dev_err_probe(&client->dev, PTR_ERR(ltc3220_state->regmap),
+ "Failed to initialize regmap\n");
+
+ i2c_set_clientdata(client, ltc3220_state);
+
+ ret = ltc3220_reset(ltc3220_state, client);
+ if (ret)
+ return dev_err_probe(&client->dev, ret, "Failed to reset device\n");
+
+ device_for_each_child_node_scoped(&client->dev, child) {
+ struct led_init_data init_data = {};
+ struct ltc3220_uled_cfg *led;
+ u32 source;
+
+ ret = fwnode_property_read_u32(child, "reg", &source);
+ if (ret)
+ return dev_err_probe(&client->dev, ret, "Couldn't read LED address\n");
+
+ if (!source || source > LTC3220_NUM_LEDS)
+ return dev_err_probe(&client->dev, -EINVAL, "LED address out of range\n");
+
+ init_data.fwnode = child;
+ init_data.devicename = "ltc3220";
+
+ if (fwnode_property_present(child, "led-sources")) {
+ if (source != 1)
+ return dev_err_probe(&client->dev, -EINVAL,
+ "Aggregated LED out of range\n");
+
+ if (aggregated_led_found)
+ return dev_err_probe(&client->dev, -EINVAL,
+ "One Aggregated LED only\n");
+
+ aggregated_led_found = true;
+ ltc3220_state->is_aggregated = true;
+
+ ret = regmap_update_bits(ltc3220_state->regmap,
+ LTC3220_COMMAND_REG,
+ LTC3220_QUICK_WRITE_MASK,
+ LTC3220_QUICK_WRITE_MASK);
+ if (ret < 0)
+ return dev_err_probe(&client->dev, ret,
+ "Failed to set quick write mode\n");
+ }
+
+ num_leds++;
+
+ /* LED node reg/index/address goes from 1 to 18 */
+ led_index = source - 1;
+ led = &ltc3220_state->uled_cfg[led_index];
+ led->led_index = led_index;
+ led->reg_value = 0;
+ led->ltc3220_state = ltc3220_state;
+ led->led_cdev.brightness_set_blocking = ltc3220_set_led_data;
+ led->led_cdev.brightness_get = ltc3220_get_led_data;
+ led->led_cdev.max_brightness = 255;
+ led->led_cdev.blink_set = ltc3220_blink_set;
+ led->led_cdev.pattern_set = ltc3220_pattern_set;
+ led->led_cdev.pattern_clear = ltc3220_pattern_clear;
+
+ ret = devm_led_classdev_register_ext(&client->dev, &led->led_cdev, &init_data);
+ if (ret)
+ return dev_err_probe(&client->dev, ret, "Failed to register LED class\n");
+ }
+
+ /*
+ * Aggregated LED mode uses hardware quick-write to control all 18 LEDs
+ * simultaneously. This is mutually exclusive with individual LED control.
+ * See Documentation/devicetree/bindings/leds/adi,ltc3220.yaml for details
+ * on how to configure aggregated LED mode.
+ */
+ if (aggregated_led_found && num_leds > 1)
+ return dev_err_probe(&client->dev, -EINVAL,
+ "Aggregated LED must be the only LED node\n");
+
+ return 0;
+}
+
+static const struct of_device_id ltc3220_of_match[] = {
+ { .compatible = "adi,ltc3220" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, ltc3220_of_match);
+
+static struct i2c_driver ltc3220_led_driver = {
+ .driver = {
+ .name = "ltc3220",
+ .of_match_table = ltc3220_of_match,
+ .pm = pm_sleep_ptr(&ltc3220_pm_ops),
+ },
+ .probe = ltc3220_probe,
+};
+module_i2c_driver(ltc3220_led_driver);
+
+MODULE_AUTHOR("Edelweise Escala <edelweise.escala@analog.com>");
+MODULE_DESCRIPTION("LED driver for LTC3220 controllers");
+MODULE_LICENSE("GPL");

--
2.43.0