From: YİĞİTCAN KAVAKLI <[email protected]> Implement a generic Linux backlight driver for the Kinetic Technologies KTD3136 36V, 6-channel LED driver.
The driver provides: - Standard Linux backlight class interface (struct backlight_ops) - 11-bit linear dimming resolution (0..2047 steps) - Optional hardware enable (HWEN) GPIO sequencing - Chip shutdown and register re-initialization upon resume/power-up - Clean devm-managed resource allocation Hardware evidence: Tested on Qualcomm SM6125 platforms (Xiaomi Redmi Note 8) with smooth dimming across the full 11-bit range and robust recovery across display power cycles. Signed-off-by: YİĞİTCAN KAVAKLI <[email protected]> --- drivers/video/backlight/Kconfig | 12 ++ drivers/video/backlight/Makefile | 1 + drivers/video/backlight/ktd3136-backlight.c | 262 ++++++++++++++++++++++++++++ 3 files changed, 275 insertions(+) diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig index dbf4ca23a9b6d8575a86e39618b312b4df43ea19..010e2ae3fa8cbd8e2f38e7941b373fbfeb5ede3f 100644 --- a/drivers/video/backlight/Kconfig +++ b/drivers/video/backlight/Kconfig @@ -207,6 +207,18 @@ config BACKLIGHT_KTZ8866 Say Y to enable the backlight driver for the Kinetic KTZ8866 found in Xiaomi Mi Pad 5 series. +config BACKLIGHT_KTD3136 + tristate "Backlight Driver for Kinetic KTD3136" + depends on I2C + select REGMAP_I2C + help + Say Y to enable the backlight driver for the Kinetic Technologies + KTD3136 3-channel I2C-controlled LED backlight driver found in mobile + phones such as the Xiaomi Redmi Note 8. + + To compile this driver as a module, choose M here: the module will + be called ktd3136-backlight. + config BACKLIGHT_SY7758 tristate "Backlight Driver for Silergy SY7758" depends on I2C diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile index 34469711c6cd957dae63c7072ade4830879aba1a..c6d324f60e021afaab1a3da1b4de74f6f2acc8f8 100644 --- a/drivers/video/backlight/Makefile +++ b/drivers/video/backlight/Makefile @@ -39,6 +39,7 @@ obj-$(CONFIG_BACKLIGHT_IPAQ_MICRO) += ipaq_micro_bl.o obj-$(CONFIG_BACKLIGHT_KTD253) += ktd253-backlight.o obj-$(CONFIG_BACKLIGHT_KTD2801) += ktd2801-backlight.o obj-$(CONFIG_BACKLIGHT_KTZ8866) += ktz8866.o +obj-$(CONFIG_BACKLIGHT_KTD3136) += ktd3136-backlight.o obj-$(CONFIG_BACKLIGHT_LM3509) += lm3509_bl.o obj-$(CONFIG_BACKLIGHT_LM3533) += lm3533_bl.o obj-$(CONFIG_BACKLIGHT_LM3630A) += lm3630a_bl.o diff --git a/drivers/video/backlight/ktd3136-backlight.c b/drivers/video/backlight/ktd3136-backlight.c new file mode 100644 index 0000000000000000000000000000000000000000..a8ebe3b23c99f3ada9f45c60688f8b8c78d72def --- /dev/null +++ b/drivers/video/backlight/ktd3136-backlight.c @@ -0,0 +1,262 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Kinetic Technologies KTD3136 3-Channel LED Backlight Driver + * + * Copyright (C) 2026 + */ + +#include <linux/backlight.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/gpio/consumer.h> +#include <linux/i2c.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/of.h> +#include <linux/property.h> +#include <linux/regulator/consumer.h> + +#define KTD3136_REG_DEV_ID 0x00 +#define KTD3136_REG_SW_RESET 0x01 +#define KTD3136_REG_MODE 0x02 +#define KTD3136_REG_CONTROL 0x03 +#define KTD3136_REG_RATIO_LSB 0x04 +#define KTD3136_REG_RATIO_MSB 0x05 +#define KTD3136_REG_PWM 0x06 +#define KTD3136_REG_STATUS 0x0A + +#define KTD3136_DEV_ID_VAL 0x18 +#define KTD3136_DEV_ID_VAL2 0x19 + +#define KTD3136_MODE_ON 0xC9 /* Boost ON, 3 channels enabled */ +#define KTD3136_MODE_STANDBY 0x98 /* Standby mode */ +#define KTD3136_CONTROL_LINEAR 0x02 /* Linear dimming mapping */ +#define KTD3136_PWM_DEFAULT 0x1B /* Default PWM/boost frequency */ + +#define KTD3136_DEFAULT_MAX_BRIGHTNESS 2047 /* 11-bit resolution */ +#define KTD3136_DEFAULT_BRIGHTNESS 2047 + +struct ktd3136_data { + struct i2c_client *client; + struct backlight_device *bd; + struct gpio_desc *enable_gpio; + struct regulator *vin; + /* Protects chip registers and state */ + struct mutex lock; + bool is_enabled; +}; + +static int ktd3136_write(struct ktd3136_data *chip, u8 reg, u8 val) +{ + int ret; + + ret = i2c_smbus_write_byte_data(chip->client, reg, val); + if (ret < 0) + dev_err(&chip->client->dev, "failed to write reg 0x%02x: %d\n", reg, ret); + + return ret; +} + +static int ktd3136_read(struct ktd3136_data *chip, u8 reg) +{ + int ret; + + ret = i2c_smbus_read_byte_data(chip->client, reg); + if (ret < 0) + dev_err(&chip->client->dev, "failed to read reg 0x%02x: %d\n", reg, ret); + + return ret; +} + +static int ktd3136_power_on(struct ktd3136_data *chip) +{ + int ret; + + if (chip->is_enabled) + return 0; + + if (chip->enable_gpio) { + gpiod_set_value_cansleep(chip->enable_gpio, 1); + /* Allow oscillator and internal logic to stabilize */ + usleep_range(2000, 3000); + } + + ret = ktd3136_write(chip, KTD3136_REG_CONTROL, KTD3136_CONTROL_LINEAR); + if (ret < 0) + goto err_off; + + ret = ktd3136_write(chip, KTD3136_REG_PWM, KTD3136_PWM_DEFAULT); + if (ret < 0) + goto err_off; + + chip->is_enabled = true; + return 0; + +err_off: + if (chip->enable_gpio) + gpiod_set_value_cansleep(chip->enable_gpio, 0); + return ret; +} + +static void ktd3136_power_off(struct ktd3136_data *chip) +{ + if (!chip->is_enabled) + return; + + ktd3136_write(chip, KTD3136_REG_MODE, KTD3136_MODE_STANDBY); + + if (chip->enable_gpio) + gpiod_set_value_cansleep(chip->enable_gpio, 0); + + chip->is_enabled = false; +} + +static int ktd3136_update_status(struct backlight_device *bd) +{ + struct ktd3136_data *chip = bl_get_data(bd); + int brightness = backlight_get_brightness(bd); + int ret = 0; + u8 lsb, msb; + + mutex_lock(&chip->lock); + + if (backlight_is_blank(bd) || brightness == 0) { + ktd3136_power_off(chip); + goto out; + } + + ret = ktd3136_power_on(chip); + if (ret < 0) + goto out; + + lsb = brightness & 0x07; + msb = (brightness >> 3) & 0xFF; + + ret = ktd3136_write(chip, KTD3136_REG_RATIO_LSB, lsb); + if (ret < 0) + goto out; + + ret = ktd3136_write(chip, KTD3136_REG_RATIO_MSB, msb); + if (ret < 0) + goto out; + + ret = ktd3136_write(chip, KTD3136_REG_MODE, KTD3136_MODE_ON); + +out: + mutex_unlock(&chip->lock); + return ret; +} + +static const struct backlight_ops ktd3136_backlight_ops = { + .options = BL_CORE_SUSPENDRESUME, + .update_status = ktd3136_update_status, +}; + +static int ktd3136_probe(struct i2c_client *client) +{ + struct device *dev = &client->dev; + struct backlight_properties props; + struct ktd3136_data *chip; + int ret, val; + u32 def_brightness = KTD3136_DEFAULT_BRIGHTNESS; + u32 max_brightness = KTD3136_DEFAULT_MAX_BRIGHTNESS; + + chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL); + if (!chip) + return -ENOMEM; + + chip->client = client; + mutex_init(&chip->lock); + + chip->vin = devm_regulator_get_optional(dev, "vin"); + if (IS_ERR(chip->vin)) { + ret = PTR_ERR(chip->vin); + if (ret != -ENODEV) + return dev_err_probe(dev, ret, "Failed to get vin regulator\n"); + chip->vin = NULL; + } + + if (chip->vin) { + ret = regulator_enable(chip->vin); + if (ret) + return dev_err_probe(dev, ret, "Failed to enable vin regulator\n"); + } + + chip->enable_gpio = devm_gpiod_get_optional(dev, "enable", GPIOD_OUT_HIGH); + if (IS_ERR(chip->enable_gpio)) + return dev_err_probe(dev, PTR_ERR(chip->enable_gpio), + "Failed to get enable GPIO\n"); + + if (chip->enable_gpio) + usleep_range(2000, 3000); + + val = ktd3136_read(chip, KTD3136_REG_DEV_ID); + if (val < 0) + return dev_err_probe(dev, val, "Failed to read device ID\n"); + + if (val != KTD3136_DEV_ID_VAL && val != KTD3136_DEV_ID_VAL2) { + dev_err(dev, "Unknown device ID: 0x%02x\n", val); + return -ENODEV; + } + + dev_info(dev, "Kinetic KTD3136 detected (ID: 0x%02x)\n", val); + + device_property_read_u32(dev, "max-brightness", &max_brightness); + if (max_brightness > KTD3136_DEFAULT_MAX_BRIGHTNESS) + max_brightness = KTD3136_DEFAULT_MAX_BRIGHTNESS; + + device_property_read_u32(dev, "default-brightness", &def_brightness); + if (def_brightness > max_brightness) + def_brightness = max_brightness; + + memset(&props, 0, sizeof(props)); + props.type = BACKLIGHT_RAW; + props.max_brightness = max_brightness; + props.brightness = def_brightness; + + chip->bd = devm_backlight_device_register(dev, dev_name(dev), dev, chip, + &ktd3136_backlight_ops, &props); + if (IS_ERR(chip->bd)) + return dev_err_probe(dev, PTR_ERR(chip->bd), + "Failed to register backlight device\n"); + + backlight_update_status(chip->bd); + + return 0; +} + +static void ktd3136_remove(struct i2c_client *client) +{ + struct ktd3136_data *chip = i2c_get_clientdata(client); + + if (chip) + ktd3136_power_off(chip); +} + +static const struct of_device_id ktd3136_of_match[] = { + { .compatible = "kinetic,ktd3136" }, + { } +}; +MODULE_DEVICE_TABLE(of, ktd3136_of_match); + +static const struct i2c_device_id ktd3136_i2c_id[] = { + { "ktd3136", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, ktd3136_i2c_id); + +static struct i2c_driver ktd3136_driver = { + .driver = { + .name = "ktd3136-backlight", + .of_match_table = ktd3136_of_match, + }, + .probe = ktd3136_probe, + .remove = ktd3136_remove, + .id_table = ktd3136_i2c_id, +}; +module_i2c_driver(ktd3136_driver); + +MODULE_AUTHOR("Antigravity Team"); +MODULE_DESCRIPTION("Kinetic Technologies KTD3136 Backlight Driver"); +MODULE_LICENSE("GPL"); -- 2.47.3
