linux-kernel - [PATCH 4/4] iio: proximity: vl53l0x-i2c: Use raw I2C access and read full device ID

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Message-Id: <20260119-vl53l0x-v1-4-cf71715a1353@protonmail.com>
Date: Mon, 19 Jan 2026 18:19:58 +0100
From: Petr Hodina via B4 Relay <devnull+petr.hodina.protonmail.com@...nel.org>
To: Song Qiang <songqiang1304521@...il.com>, 
 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>, Liam Girdwood <lgirdwood@...il.com>, 
 Mark Brown <broonie@...nel.org>, David Heidelberg <david@...t.cz>
Cc: linux-iio@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Petr Hodina <petr.hodina@...tonmail.com>
Subject: [PATCH 4/4] iio: proximity: vl53l0x-i2c: Use raw I2C access and
 read full device ID

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

Replace SMBus byte reads with raw I2C transfers when reading the device
identification registers.

The VL53L0X exposes its model and revision as 16-bit registers, which are
more accurately accessed using standard I2C send/receive operations.
This also avoids depending on SMBus byte data support, which is not
guaranteed on all I2C adapters.

Read and log both model and revision IDs, and validate the model ID
during probe to ensure the expected device is present.

Signed-off-by: Petr Hodina <petr.hodina@...tonmail.com>
---
 drivers/iio/proximity/vl53l0x-i2c.c | 45 +++++++++++++++++++++++++++++++------
 1 file changed, 38 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/proximity/vl53l0x-i2c.c b/drivers/iio/proximity/vl53l0x-i2c.c
index 6901ce7dd835..a2de4cc16a43 100644
--- a/drivers/iio/proximity/vl53l0x-i2c.c
+++ b/drivers/iio/proximity/vl53l0x-i2c.c
@@ -320,11 +320,35 @@ static const struct iio_trigger_ops vl53l0x_trigger_ops = {
 	.validate_device = iio_trigger_validate_own_device,
 };
 
+
+static int vl53l0x_read_word(struct i2c_client *client, u8 reg, u16 *val)
+{
+	int ret;
+	u8 buf[2];
+
+	ret = i2c_master_send(client, &reg, 1);
+	if (ret < 0)
+		return ret;
+	if (ret != 1)
+		return -EIO;
+
+	ret = i2c_master_recv(client, buf, 2);
+	if (ret < 0)
+		return ret;
+	if (ret != 2)
+		return -EIO;
+
+	*val = (buf[0] << 8) | buf[1];
+
+	return 0;
+}
+
 static int vl53l0x_probe(struct i2c_client *client)
 {
 	struct vl53l0x_data *data;
 	struct iio_dev *indio_dev;
 	int ret;
+	u16 model, rev;
 
 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 	if (!indio_dev)
@@ -339,13 +363,6 @@ static int vl53l0x_probe(struct i2c_client *client)
 				     I2C_FUNC_SMBUS_BYTE_DATA))
 		return -EOPNOTSUPP;
 
-	ret = i2c_smbus_read_byte_data(data->client, VL_REG_IDENTIFICATION_MODEL_ID);
-	if (ret < 0)
-		return -EINVAL;
-
-	if (ret != VL53L0X_MODEL_ID_VAL)
-		dev_info(&client->dev, "Unknown model id: 0x%x", ret);
-
 	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),
@@ -372,6 +389,20 @@ static int vl53l0x_probe(struct i2c_client *client)
 	if (ret)
 		return ret;
 
+	ret = vl53l0x_read_word(client, 0xC0, &model);
+	if (ret)
+		return dev_err_probe(&client->dev, ret, "Failed to read model ID\n");
+
+	ret = vl53l0x_read_word(client, 0xC2, &rev);
+	if (ret)
+		return dev_err_probe(&client->dev, ret, "Failed to read revision ID\n");
+
+	dev_info(&client->dev, "VL53L0X model=0x%04x rev=0x%04x\n", model, rev);
+
+	if ((model >> 8) != VL53L0X_MODEL_ID_VAL)
+		return dev_err_probe(&client->dev, -ENODEV,
+			"Unexpected model ID: 0x%04x\n", model);
+
 	indio_dev->name = "vl53l0x";
 	indio_dev->info = &vl53l0x_info;
 	indio_dev->channels = vl53l0x_channels;

-- 
2.52.0