[PATCH 3/3] iio: proximity: Add Benewake TF-Luna LiDAR driver

[Vidhu Sarwal via B4 Relay <devnull+vidhu.linux.gmail.com@kernel.org>]

From: Vidhu Sarwal <vidhu.linux@gmail.com>

Add a driver for the Benewake TF-Luna, a single-point time-of-flight
LiDAR distance sensor with a range of 0.2 m to 8 m, connected over I2C.

The sensor is run in trigger mode. Each read starts one measurement and
waits for the timestamp register to change before reading the result.
In continuous mode a read can catch the sensor in the middle of updating
its result registers unless it is synchronised to the data ready output,
which this driver does not use yet.

When the signal strength is too low the sensor reports a dummy distance
of 0, so such readings, as well as overexposed ones, return -ENODATA
instead of a distance.

The datasheet is available at:
https://en.benewake.com/uploadfiles/2025/04/20250430174501874.pdf

Signed-off-by: Vidhu Sarwal <vidhu.linux@gmail.com>
---
 MAINTAINERS                     |   1 +
 drivers/iio/proximity/Kconfig   |  11 ++
 drivers/iio/proximity/Makefile  |   1 +
 drivers/iio/proximity/tf-luna.c | 254 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 267 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 24fa7cdf6a57..20e43a003bed 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4667,6 +4667,7 @@ M:	Vidhu Sarwal <vidhu.linux@gmail.com>
 L:	linux-iio@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/iio/proximity/benewake,tf-luna.yaml
+F:	drivers/iio/proximity/tf-luna.c
 
 BFQ I/O SCHEDULER
 M:	Yu Kuai <yukuai@fygo.io>
diff --git a/drivers/iio/proximity/Kconfig b/drivers/iio/proximity/Kconfig
index f3cec799df67..d16458ea4b0f 100644
--- a/drivers/iio/proximity/Kconfig
+++ b/drivers/iio/proximity/Kconfig
@@ -222,6 +222,17 @@ config SRF08
 	  To compile this driver as a module, choose M here: the
 	  module will be called srf08.
 
+config TF_LUNA
+	tristate "Benewake TF-Luna LiDAR distance sensor"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  Say Y here to build a driver for the Benewake TF-Luna LiDAR
+	  distance sensor connected over I2C.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called tf-luna.
+
 config VCNL3020
 	tristate "VCNL3020 proximity sensor"
 	select REGMAP_I2C
diff --git a/drivers/iio/proximity/Makefile b/drivers/iio/proximity/Makefile
index 8a65e42fbea0..43741115a921 100644
--- a/drivers/iio/proximity/Makefile
+++ b/drivers/iio/proximity/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_SX9324)		+= sx9324.o
 obj-$(CONFIG_SX9360)		+= sx9360.o
 obj-$(CONFIG_SX_COMMON) 	+= sx_common.o
 obj-$(CONFIG_SX9500)		+= sx9500.o
+obj-$(CONFIG_TF_LUNA)		+= tf-luna.o
 obj-$(CONFIG_VCNL3020)		+= vcnl3020.o
 obj-$(CONFIG_VCNL36829)		+= vcnl36829.o
 obj-$(CONFIG_VL53L0X_I2C)	+= vl53l0x-i2c.o
diff --git a/drivers/iio/proximity/tf-luna.c b/drivers/iio/proximity/tf-luna.c
new file mode 100644
index 000000000000..b2f6e664b614
--- /dev/null
+++ b/drivers/iio/proximity/tf-luna.c
@@ -0,0 +1,254 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Benewake TF-Luna LiDAR distance sensor
+ *
+ * Copyright (C) 2026 Vidhu Sarwal <vidhu.linux@gmail.com>
+ *
+ * Datasheet: https://en.benewake.com/uploadfiles/2025/04/20250430174501874.pdf
+ *
+ * The I2C register map is in appendix III of the TF-Luna product manual
+ * (SJ-PM-TF-Luna A05). Default 7-bit I2C address is 0x10.
+ */
+
+#include <linux/array_size.h>
+#include <linux/bits.h>
+#include <linux/cleanup.h>
+#include <linux/delay.h>
+#include <linux/dev_printk.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/iopoll.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/string.h>
+#include <linux/time.h>
+#include <linux/types.h>
+
+#include <asm/byteorder.h>
+
+#include <linux/iio/iio.h>
+
+#define TF_LUNA_REG_DIST		0x00
+#define TF_LUNA_REG_TICK		0x06
+#define TF_LUNA_REG_VERSION		0x0A
+#define TF_LUNA_REG_MODE		0x23
+#define TF_LUNA_REG_TRIG_ONE_SHOT	0x24
+#define TF_LUNA_REG_SIGNATURE		0x3C
+
+#define TF_LUNA_MODE_TRIGGER		0x01
+#define TF_LUNA_TRIG_ONE_SHOT		0x01
+
+/* Below this the sensor reports a dummy distance of 0 */
+#define TF_LUNA_AMP_MIN			100
+#define TF_LUNA_AMP_OVEREXPOSED		0xFFFF
+
+/* A measurement takes 10-20 ms in trigger mode */
+#define TF_LUNA_POLL_US			(2 * USEC_PER_MSEC)
+#define TF_LUNA_TIMEOUT_US		(100 * USEC_PER_MSEC)
+
+struct tf_luna_data {
+	struct regmap *regmap;
+	/* Serialises the trigger, poll and read of a single measurement */
+	struct mutex lock;
+};
+
+static const struct regmap_config tf_luna_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = TF_LUNA_REG_SIGNATURE + 3,
+};
+
+static int tf_luna_read_tick(struct tf_luna_data *data, u16 *tick)
+{
+	__le16 val;
+	int ret;
+
+	ret = regmap_bulk_read(data->regmap, TF_LUNA_REG_TICK, &val, sizeof(val));
+	if (ret)
+		return ret;
+
+	*tick = le16_to_cpu(val);
+	return 0;
+}
+
+static int tf_luna_measure(struct tf_luna_data *data, int *dist)
+{
+	__le16 buf[2];	/* distance in cm, signal strength */
+	u16 old_tick, tick, amp;
+	int ret, err;
+
+	guard(mutex)(&data->lock);
+
+	ret = tf_luna_read_tick(data, &old_tick);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(data->regmap, TF_LUNA_REG_TRIG_ONE_SHOT,
+			   TF_LUNA_TRIG_ONE_SHOT);
+	if (ret)
+		return ret;
+
+	/* The tick register is a timestamp, it changes with each measurement */
+	ret = read_poll_timeout(tf_luna_read_tick, err, err || tick != old_tick,
+				TF_LUNA_POLL_US, TF_LUNA_TIMEOUT_US, true,
+				data, &tick);
+	if (ret)
+		return ret;
+	if (err)
+		return err;
+
+	ret = regmap_bulk_read(data->regmap, TF_LUNA_REG_DIST, buf, sizeof(buf));
+	if (ret)
+		return ret;
+
+	amp = le16_to_cpu(buf[1]);
+	if (amp < TF_LUNA_AMP_MIN || amp == TF_LUNA_AMP_OVEREXPOSED)
+		return -ENODATA;
+
+	*dist = le16_to_cpu(buf[0]);
+	return 0;
+}
+
+static int tf_luna_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct tf_luna_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = tf_luna_measure(data, val);
+		if (ret)
+			return ret;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		/* Distance is in cm */
+		*val = 0;
+		*val2 = 10000;
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info tf_luna_info = {
+	.read_raw = tf_luna_read_raw,
+};
+
+static const struct iio_chan_spec tf_luna_channels[] = {
+	{
+		.type = IIO_DISTANCE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+	},
+};
+
+static int tf_luna_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct tf_luna_data *data;
+	struct iio_dev *indio_dev;
+	unsigned int mode;
+	u8 signature[4];
+	u8 version[3];
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+
+	ret = devm_mutex_init(dev, &data->lock);
+	if (ret)
+		return ret;
+
+	data->regmap = devm_regmap_init_i2c(client, &tf_luna_regmap_config);
+	if (IS_ERR(data->regmap))
+		return dev_err_probe(dev, PTR_ERR(data->regmap),
+				     "Failed to initialize regmap\n");
+
+	ret = devm_regulator_get_enable(dev, "vcc");
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to enable vcc regulator\n");
+
+	/* Boot time is not documented, about 350 ms was measured */
+	fsleep(500 * USEC_PER_MSEC);
+
+	ret = regmap_bulk_read(data->regmap, TF_LUNA_REG_SIGNATURE, signature,
+			       sizeof(signature));
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to read signature\n");
+
+	if (memcmp(signature, "LUNA", sizeof(signature)))
+		dev_info(dev, "Unknown signature %*ph, continuing\n",
+			 (int)sizeof(signature), signature);
+
+	ret = regmap_bulk_read(data->regmap, TF_LUNA_REG_VERSION, version,
+			       sizeof(version));
+	if (ret)
+		return ret;
+
+	dev_dbg(dev, "Firmware version %u.%u.%u\n",
+		version[2], version[1], version[0]);
+
+	/*
+	 * In continuous mode a read can catch the sensor updating its result
+	 * registers unless it is synchronised to the data ready output. Use
+	 * trigger mode and start each measurement on demand instead.
+	 */
+	ret = regmap_write(data->regmap, TF_LUNA_REG_MODE, TF_LUNA_MODE_TRIGGER);
+	if (ret)
+		return ret;
+
+	/*
+	 * The sensor silently drops writes it is not ready for, so check that
+	 * the mode was set. A write takes up to 100 ms to read back.
+	 */
+	fsleep(100 * USEC_PER_MSEC);
+
+	ret = regmap_read(data->regmap, TF_LUNA_REG_MODE, &mode);
+	if (ret)
+		return ret;
+
+	if (mode != TF_LUNA_MODE_TRIGGER)
+		return dev_err_probe(dev, -EIO, "Failed to set trigger mode\n");
+
+	indio_dev->name = "tf-luna";
+	indio_dev->info = &tf_luna_info;
+	indio_dev->channels = tf_luna_channels;
+	indio_dev->num_channels = ARRAY_SIZE(tf_luna_channels);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct i2c_device_id tf_luna_id[] = {
+	{ .name = "tf-luna" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tf_luna_id);
+
+static const struct of_device_id tf_luna_of_match[] = {
+	{ .compatible = "benewake,tf-luna" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, tf_luna_of_match);
+
+static struct i2c_driver tf_luna_driver = {
+	.driver = {
+		.name = "tf-luna",
+		.of_match_table = tf_luna_of_match,
+	},
+	.probe = tf_luna_probe,
+	.id_table = tf_luna_id,
+};
+module_i2c_driver(tf_luna_driver);
+
+MODULE_AUTHOR("Vidhu Sarwal <vidhu.linux@gmail.com>");
+MODULE_DESCRIPTION("Benewake TF-Luna LiDAR distance sensor driver");
+MODULE_LICENSE("GPL");

-- 
2.53.0