Message-Id: <20260119-tsc3400-v1-2-82a65c5417aa@protonmail.com>
Date: Mon, 19 Jan 2026 18:19:07 +0100
From: Petr Hodina via B4 Relay <devnull+petr.hodina.protonmail.com@...nel.org>
To: Jonathan Cameron <jic23@...nel.org>, 
 David Lechner <dlechner@...libre.com>, 
 Nuno Sá <nuno.sa@...log.com>, 
 Andy Shevchenko <andy@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, Bjorn Andersson <andersson@...nel.org>, 
 Konrad Dybcio <konradybcio@...nel.org>, David Heidelberg <david@...t.cz>
Cc: linux-iio@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org, 
 Petr Hodina <petr.hodina@...tonmail.com>
Subject: [PATCH 2/3] iio: light: add AMS TCS3400 RGB and RGB-IR color
 sensor driver

From: Petr Hodina <petr.hodina@...tonmail.com>

Add support for the AMS TCS3400 I2C color light-to-digital converter.
The driver supports RGBC and RGB-IR modes, programmable integration
time, optional interrupt-driven buffered capture, and regulator-based
power control.

Signed-off-by: Petr Hodina <petr.hodina@...tonmail.com>
---
 MAINTAINERS                 |   1 +
 drivers/iio/light/Kconfig   |  11 +
 drivers/iio/light/Makefile  |   1 +
 drivers/iio/light/tcs3400.c | 505 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 518 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index ab5307a34180..3d7d0aa10c55 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22871,6 +22871,7 @@ M:	Petr Hodina
 L:	Petr Hodina <petr.hodina@...tonmail.com>
 S:	Petr Hodina <petr.hodina@...tonmail.com>
 F:	Documentation/devicetree/bindings/iio/light/ams,tcs3400.yaml
+F:	drivers/iio/light/tcs3400.c
 
 ROHM BH1745 COLOUR SENSOR
 M:	Mudit Sharma <muditsharma.info@...il.com>
diff --git a/drivers/iio/light/Kconfig b/drivers/iio/light/Kconfig
index ac1408d374c9..73419d80e3a7 100644
--- a/drivers/iio/light/Kconfig
+++ b/drivers/iio/light/Kconfig
@@ -580,6 +580,17 @@ config ST_UVIS25_SPI
 	depends on ST_UVIS25
 	select REGMAP_SPI
 
+config TCS3400
+	tristate "AMS TCS3400 color light-to-digital converter"
+	depends on I2C
+	default n
+	help
+	  If you say yes here you get support for the AMS TCS3400.
+	  This sensor can detect ambient light and color (RGB) values.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called tcs3400.
+
 config TCS3414
 	tristate "TAOS TCS3414 digital color sensor"
 	depends on I2C
diff --git a/drivers/iio/light/Makefile b/drivers/iio/light/Makefile
index c0048e0d5ca8..847ef7bf0f57 100644
--- a/drivers/iio/light/Makefile
+++ b/drivers/iio/light/Makefile
@@ -54,6 +54,7 @@ obj-$(CONFIG_STK3310)          += stk3310.o
 obj-$(CONFIG_ST_UVIS25)		+= st_uvis25_core.o
 obj-$(CONFIG_ST_UVIS25_I2C)	+= st_uvis25_i2c.o
 obj-$(CONFIG_ST_UVIS25_SPI)	+= st_uvis25_spi.o
+obj-$(CONFIG_TCS3400)		+= tcs3400.o
 obj-$(CONFIG_TCS3414)		+= tcs3414.o
 obj-$(CONFIG_TCS3472)		+= tcs3472.o
 obj-$(CONFIG_SENSORS_TSL2563)	+= tsl2563.o
diff --git a/drivers/iio/light/tcs3400.c b/drivers/iio/light/tcs3400.c
new file mode 100644
index 000000000000..22c8c4e803cf
--- /dev/null
+++ b/drivers/iio/light/tcs3400.c
@@ -0,0 +1,505 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TCS3400 - AMS/TAOS color light sensor with RGBC and RGB-IR channels
+ *
+ * Copyright (c) 2025 Petr Hodina
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/regulator/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/pm_runtime.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+
+#define TCS3400_DRV_NAME "tcs3400"
+#define TCS3400_CMD_REG(reg) (0x80 | (reg))
+#define TCS3400_CMD_SPECIAL 0xE0
+#define TCS3400_CMD_ALS_INT_CLR 0xE6
+#define TCS3400_CMD_ALL_INT_CLR 0xE7
+#define TCS3400_ENABLE 0x00
+#define TCS3400_ATIME 0x01
+#define TCS3400_WTIME 0x03
+#define TCS3400_PERSIST 0x0C
+#define TCS3400_CONTROL 0x0F /* Gain */
+#define TCS3400_STATUS 0x13
+#define TCS3400_CDATAL 0x14 /* Clear low */
+#define TCS3400_RDATAL 0x16
+#define TCS3400_GDATAL 0x18
+#define TCS3400_BDATAL 0x1A
+#define TCS3400_ID 0x12
+#define TCS3400_CHSEL 0xC0 /* Access IR channel: 0x00 RGBC, 0x80 RGB-IR */
+#define TCS3400_EN_PON BIT(0)
+#define TCS3400_EN_AEN BIT(1)
+#define TCS3400_EN_AIEN BIT(4)
+#define TCS3400_STATUS_AVALID BIT(0)
+#define TCS3400_STATUS_AINT BIT(4)
+#define TCS3400_GAIN_1X 0x00
+#define TCS3400_GAIN_4X 0x01
+#define TCS3400_GAIN_16X 0x02
+#define TCS3400_GAIN_64X 0x03
+#define TCS3400_MAX_ATIME 256
+
+#define TCS3400_IIO_CHANNEL(_index, _mod) { \
+	.type = IIO_INTENSITY, \
+	.modified = 1, \
+	.channel2 = IIO_MOD_##_mod, \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
+			      BIT(IIO_CHAN_INFO_SCALE), \
+			      BIT(IIO_CHAN_INFO_SCALE) | \
+			      BIT(IIO_CHAN_INFO_INT_TIME), \
+	.indexed = 1, \
+	.channel = _index, \
+	.scan_index = _index, \
+	.scan_type = { \
+		.sign = 'u', \
+		.realbits = 16, \
+		.storagebits = 16, \
+		.endianness = IIO_LE, \
+	}, \
+}
+
+struct tcs3400_data {
+	struct i2c_client *client;
+	struct mutex lock;
+	struct regulator *vdd_supply;
+	u8 atime;
+	u8 gain;
+	u8 channel_mode; /* 0x00 or 0x80 */
+	u16 clear_ir; /* clear when mode=0x00, IR when mode=0x80 */
+	u16 red;
+	u16 green;
+	u16 blue;
+};
+
+static const int tcs3400_gains[] = {1, 4, 16, 64};
+
+static int tcs3400_power_on(struct tcs3400_data *data)
+{
+	int ret;
+
+	ret = regulator_enable(data->vdd_supply);
+	if (ret)
+		return ret;
+
+	msleep(20);
+
+	return 0;
+}
+
+static void tcs3400_power_off(struct tcs3400_data *data)
+{
+	regulator_disable(data->vdd_supply);
+}
+
+static int tcs3400_write_reg(struct tcs3400_data *data, u8 reg, u8 val)
+{
+	return i2c_smbus_write_byte_data(data->client, TCS3400_CMD_REG(reg), val);
+}
+
+static int tcs3400_read_reg(struct tcs3400_data *data, u8 reg, u8 *val)
+{
+	int ret = i2c_smbus_read_byte_data(data->client, TCS3400_CMD_REG(reg));
+
+	if (ret < 0)
+		return ret;
+	*val = ret;
+
+	return 0;
+}
+
+static int tcs3400_read_word(struct tcs3400_data *data, u8 reg, u16 *val)
+{
+
+	__le16 buf;
+	int ret = i2c_smbus_read_i2c_block_data(data->client,
+						TCS3400_CMD_REG(reg), 2, (u8 *)&buf);
+	if (ret < 0)
+		return ret;
+	*val = le16_to_cpu(buf);
+	return 0;
+}
+static int tcs3400_clear_interrupt(struct tcs3400_data *data)
+{
+
+	return i2c_smbus_write_byte(data->client, TCS3400_CMD_ALS_INT_CLR);
+}
+
+static int tcs3400_read_channels(struct tcs3400_data *data)
+{
+
+	int ret, retries = 20;
+	u8 status;
+
+	do {
+		ret = tcs3400_read_reg(data, TCS3400_STATUS, &status);
+		if (ret)
+			return ret;
+		if (status & TCS3400_STATUS_AVALID)
+			break;
+		usleep_range(5000, 6000);
+	} while (--retries);
+	if (!retries) {
+		dev_warn(&data->client->dev, "Timeout waiting for valid data\n");
+		return -ETIMEDOUT;
+	}
+	ret = tcs3400_read_word(data, TCS3400_CDATAL, &data->clear_ir);
+	if (ret)
+		return ret;
+
+	ret = tcs3400_read_word(data, TCS3400_RDATAL, &data->red);
+	if (ret)
+		return ret;
+
+	ret = tcs3400_read_word(data, TCS3400_GDATAL, &data->green);
+	if (ret)
+		return ret;
+
+	ret = tcs3400_read_word(data, TCS3400_BDATAL, &data->blue);
+	if (ret)
+		return ret;
+	return 0;
+}
+
+static irqreturn_t tcs3400_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct tcs3400_data *data = iio_priv(indio_dev);
+	u16 buf[4];
+	int ret;
+
+	mutex_lock(&data->lock);
+	ret = tcs3400_read_channels(data);
+	if (!ret) {
+		buf[0] = data->clear_ir;
+		buf[1] = data->red;
+		buf[2] = data->green;
+		buf[3] = data->blue;
+		iio_push_to_buffers_with_timestamp(indio_dev, buf,
+						   iio_get_time_ns(indio_dev));
+	}
+	mutex_unlock(&data->lock);
+
+	iio_trigger_notify_done(indio_dev->trig);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t tcs3400_irq_handler(int irq, void *priv)
+{
+	struct iio_dev *indio_dev = priv;
+	struct tcs3400_data *data = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&data->lock);
+	ret = tcs3400_read_channels(data);
+	if (!ret)
+		iio_trigger_poll_nested(indio_dev->trig);
+
+	tcs3400_clear_interrupt(data);
+	mutex_unlock(&data->lock);
+
+	return IRQ_HANDLED;
+}
+
+static int tcs3400_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct tcs3400_data *data = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&data->lock);
+	ret = tcs3400_read_channels(data);
+	if (ret) {
+		mutex_unlock(&data->lock);
+		return ret;
+	}
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		switch (chan->channel2) {
+		case IIO_MOD_LIGHT_CLEAR:
+			*val = data->clear_ir;
+			break;
+		case IIO_MOD_LIGHT_RED:
+			*val = data->red;
+			break;
+		case IIO_MOD_LIGHT_GREEN:
+			*val = data->green;
+			break;
+		case IIO_MOD_LIGHT_BLUE:
+			*val = data->blue;
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_INT_TIME:
+		*val = 0;
+		*val2 = (TCS3400_MAX_ATIME - data->atime) * 2780000; /* 2.78 ms per cycle */
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	mutex_unlock(&data->lock);
+
+	return ret;
+}
+
+static int tcs3400_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct tcs3400_data *data = iio_priv(indio_dev);
+	int i, ret = 0;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_INT_TIME:
+		if (val != 0)
+			return -EINVAL;
+		i = TCS3400_MAX_ATIME - DIV_ROUND_CLOSEST(val2, 2780000);
+		if (i < 1 || i >= TCS3400_MAX_ATIME)
+			return -EINVAL;
+		mutex_lock(&data->lock);
+		data->atime = i;
+		ret = tcs3400_write_reg(data, TCS3400_ATIME, data->atime);
+		mutex_unlock(&data->lock);
+		return ret;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_chan_spec tcs3400_channels[] = {
+	TCS3400_IIO_CHANNEL(0, LIGHT_CLEAR),
+	TCS3400_IIO_CHANNEL(1, LIGHT_RED),
+	TCS3400_IIO_CHANNEL(2, LIGHT_GREEN),
+	TCS3400_IIO_CHANNEL(3, LIGHT_BLUE),
+	IIO_CHAN_SOFT_TIMESTAMP(4),
+};
+
+static ssize_t tcs3400_enable_show(struct device *dev,
+				   struct device_attribute *attr,
+				   char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct tcs3400_data *data = iio_priv(indio_dev);
+	u8 enable;
+	int ret;
+
+	ret = tcs3400_read_reg(data, TCS3400_ENABLE, &enable);
+	if (ret)
+		return ret;
+	return sprintf(buf, "%d\n", !!(enable & (TCS3400_EN_PON | TCS3400_EN_AEN)));
+}
+
+static ssize_t tcs3400_enable_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct tcs3400_data *data = iio_priv(indio_dev);
+	bool enable;
+	int ret;
+	u8 val;
+
+	ret = kstrtobool(buf, &enable);
+	if (ret)
+		return ret;
+	mutex_lock(&data->lock);
+	if (enable)
+		val = TCS3400_EN_PON | TCS3400_EN_AEN;
+	else
+		val = 0;
+	ret = tcs3400_write_reg(data, TCS3400_ENABLE, val);
+	mutex_unlock(&data->lock);
+	if (ret)
+		return ret;
+
+	if (enable)
+		msleep(20);
+	return len;
+}
+
+static ssize_t tcs3400_ir_mode_show(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct tcs3400_data *data = iio_priv(indio_dev);
+
+	return sprintf(buf, "%d\n", !!data->channel_mode);
+}
+
+static ssize_t tcs3400_ir_mode_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct tcs3400_data *data = iio_priv(indio_dev);
+	bool enable;
+	int ret;
+
+	ret = kstrtobool(buf, &enable);
+	if (ret)
+		return ret;
+	mutex_lock(&data->lock);
+	data->channel_mode = enable ? 0x80 : 0x00;
+	ret = tcs3400_write_reg(data, TCS3400_CHSEL, data->channel_mode);
+	mutex_unlock(&data->lock);
+	return ret ? ret : len;
+}
+
+static IIO_DEVICE_ATTR(enable, 0644, tcs3400_enable_show, tcs3400_enable_store, 0);
+static IIO_DEVICE_ATTR(ir_mode, 0644, tcs3400_ir_mode_show, tcs3400_ir_mode_store, 0);
+
+static struct attribute *tcs3400_attributes[] = {
+	&iio_dev_attr_enable.dev_attr.attr,
+	&iio_dev_attr_ir_mode.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group tcs3400_attribute_group = {
+	.attrs = tcs3400_attributes,
+};
+
+static const struct iio_info tcs3400_info = {
+	.read_raw = tcs3400_read_raw,
+	.write_raw = tcs3400_write_raw,
+	.attrs = &tcs3400_attribute_group,
+};
+
+static int tcs3400_probe(struct i2c_client *client)
+{
+	struct tcs3400_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+	u8 id;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	data->client = client;
+	mutex_init(&data->lock);
+
+	i2c_set_clientdata(client, indio_dev);
+
+	data->vdd_supply = devm_regulator_get(&client->dev, "vdd");
+	if (IS_ERR(data->vdd_supply))
+		return dev_err_probe(&client->dev, PTR_ERR(data->vdd_supply),
+				     "Unable to get VDD regulator\n");
+
+	ret = tcs3400_power_on(data);
+	if (ret)
+		goto err_power_off;
+
+	ret = i2c_smbus_read_byte_data(client, TCS3400_CMD_REG(TCS3400_ID));
+	if (ret < 0) {
+		ret = -ENODEV;
+		goto err_power_off;
+		return ret;
+	}
+
+	id = ret;
+	if (id == 0x90)
+		dev_info(&client->dev, "TCS3401/5 Chip ID: 0x%02x\n", id);
+	if (id == 0x93)
+		dev_info(&client->dev, "TCS3403/7 Chip ID: 0x%02x\n", id);
+	else {
+		dev_err(&client->dev, "Unknown chip ID: 0x%02x\n", id);
+		ret = -ENODEV;
+	}
+
+	data->atime = 0xF6; /* ~27.8 ms integration */
+	data->gain = TCS3400_GAIN_1X;
+	data->channel_mode = 0x00;
+
+	tcs3400_write_reg(data, TCS3400_ATIME, data->atime);
+	tcs3400_write_reg(data, TCS3400_CONTROL, data->gain);
+	tcs3400_write_reg(data, TCS3400_PERSIST, 0x00); /* interrupt every cycle */
+	tcs3400_write_reg(data, TCS3400_CHSEL, data->channel_mode); /* RGBC mode */
+
+	tcs3400_write_reg(data, TCS3400_ENABLE,
+			  TCS3400_EN_PON | TCS3400_EN_AEN | TCS3400_EN_AIEN);
+
+	indio_dev->name = TCS3400_DRV_NAME;
+	indio_dev->channels = tcs3400_channels;
+	indio_dev->num_channels = ARRAY_SIZE(tcs3400_channels);
+	indio_dev->info = &tcs3400_info;
+	indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_TRIGGERED;
+
+	ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev,
+					      NULL,
+					      tcs3400_trigger_handler,
+					      NULL);
+	if (ret)
+		goto err_power_off;
+	if (client->irq > 0) {
+		ret = devm_request_threaded_irq(&client->dev, client->irq,
+						NULL, tcs3400_irq_handler,
+						IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+						"tcs3400_irq", indio_dev);
+		if (ret)
+			goto err_power_off;
+	}
+
+	ret = devm_iio_device_register(&client->dev, indio_dev);
+	if (ret)
+		goto err_power_off;
+	return 0;
+err_power_off:
+	tcs3400_write_reg(data, TCS3400_ENABLE, 0);
+	tcs3400_power_off(data);
+	return ret;
+}
+
+static void tcs3400_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct tcs3400_data *data = iio_priv(indio_dev);
+
+	tcs3400_write_reg(data, TCS3400_ENABLE, 0);
+	tcs3400_power_off(data);
+}
+
+static const struct of_device_id tcs3400_of_match[] = {
+	{ .compatible = "ams,tcs3400" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, tcs3400_of_match);
+
+static const struct i2c_device_id tcs3400_id[] = {
+	{ "tcs3400", 0 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(i2c, tcs3400_id);
+
+static struct i2c_driver tcs3400_driver = {
+	.driver = {
+		.name = TCS3400_DRV_NAME,
+		.of_match_table = tcs3400_of_match,
+	},
+	.probe = tcs3400_probe,
+	.remove = tcs3400_remove,
+	.id_table = tcs3400_id,
+};
+
+module_i2c_driver(tcs3400_driver);
+MODULE_AUTHOR("Petr Hodina <petr.hodina@...tonmail.com>");
+MODULE_DESCRIPTION("AMS TCS3400 RGB/IR color sensor IIO driver");
+MODULE_LICENSE("GPL");

-- 
2.52.0

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