[PATCH 0/2] iio: humidity: Add support for en21x sensor family

[PATCH 0/2] iio: humidity: Add support for en21x sensor family

[Joshua Felmeden]

This patch series adds support for the
ENS210/ENS210A/ENS211/ENS212/ENS213A/ENS215 temperature and humidity
sensors.

Patch 1 adds the required device tree bindings.

Patch 2 adds the driver, providing the probe and read functions.

Signed-off-by: Joshua Felmeden <jfelmeden@thegoodpenguin.co.uk>
---
Joshua Felmeden (2):
      dt-bindings: iio: humidity: add ENS21x sensor family
      iio: humidity: Add support for ENS21x

 .../bindings/iio/humidity/sciosense,ens21x.yaml    |  50 +++
 drivers/iio/humidity/Kconfig                       |  11 +
 drivers/iio/humidity/Makefile                      |   1 +
 drivers/iio/humidity/ens21x.c                      | 348 +++++++++++++++++++++
 4 files changed, 410 insertions(+)
---
base-commit: 1ebab783647a9e3bf357002d5c4ff060c8474a0a
change-id: 20240709-ens21x-8f2530968f2e

Best regards,
-- 
Joshua Felmeden <jfelmeden@thegoodpenguin.co.uk>

[PATCH 1/2] dt-bindings: iio: humidity: add ENS21x sensor family

[Joshua Felmeden]

Add device tree documentation for ENS21x family of temperature and
humidity sensors

Signed-off-by: Joshua Felmeden <jfelmeden@thegoodpenguin.co.uk>
---
 .../bindings/iio/humidity/sciosense,ens21x.yaml    | 50 ++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/humidity/sciosense,ens21x.yaml b/Documentation/devicetree/bindings/iio/humidity/sciosense,ens21x.yaml
new file mode 100644
index 000000000000..3140349a58b8
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/humidity/sciosense,ens21x.yaml
@@ -0,0 +1,50 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/humidity/sciosense,ens21x.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ScioSense ENS21x temperature and humidity sensor
+
+maintainers:
+  - Joshua Felmeden <jfelmeden@thegoodpenguin.co.uk>
+
+description: |
+  Temperature and Humidity sensor.
+
+  Datasheet:
+    https://www.sciosense.com/wp-content/uploads/2024/04/ENS21x-Datasheet.pdf
+    https://www.sciosense.com/wp-content/uploads/2023/12/ENS210-Datasheet.pdf
+
+properties:
+  compatible:
+    enum:
+      - sciosense,ens210
+      - sciosense,ens210a
+      - sciosense,ens211
+      - sciosense,ens212
+      - sciosense,ens213a
+      - sciosense,ens215
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    i2c {
+       #address-cells = <1>;
+       #size-cells = <0>;
+
+       temperature-sensor@43 {
+           compatible = "sciosense,ens210";
+           reg = <0x43>;
+       };
+    };
+...
+

-- 
2.39.2

[PATCH 2/2] iio: humidity: Add support for ENS21x

[Joshua Felmeden]

Add support for ENS210/ENS210A/ENS211/ENS212/ENS213A/ENS215.

The ENS21x is a family of temperature and relative humidity sensors with
accuracies tailored to the needs of specific applications.

Signed-off-by: Joshua Felmeden <jfelmeden@thegoodpenguin.co.uk>
---
 drivers/iio/humidity/Kconfig  |  11 ++
 drivers/iio/humidity/Makefile |   1 +
 drivers/iio/humidity/ens21x.c | 348 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 360 insertions(+)

diff --git a/drivers/iio/humidity/Kconfig b/drivers/iio/humidity/Kconfig
index b15b7a3b66d5..ff62abf730d1 100644
--- a/drivers/iio/humidity/Kconfig
+++ b/drivers/iio/humidity/Kconfig
@@ -25,6 +25,17 @@ config DHT11
 	  Other sensors should work as well as long as they speak the
 	  same protocol.
 
+config ENS21X
+	tristate "ENS21X temperature and humidity sensor"
+	depends on I2C
+	help
+	  Say yes here to get support for the ScioSense ENS21X family of
+	  humidity and temperature sensors.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called ens21x.
+
+
 config HDC100X
 	tristate "TI HDC100x relative humidity and temperature sensor"
 	depends on I2C
diff --git a/drivers/iio/humidity/Makefile b/drivers/iio/humidity/Makefile
index 5fbeef299f61..26590d06d11f 100644
--- a/drivers/iio/humidity/Makefile
+++ b/drivers/iio/humidity/Makefile
@@ -5,6 +5,7 @@
 
 obj-$(CONFIG_AM2315) += am2315.o
 obj-$(CONFIG_DHT11) += dht11.o
+obj-$(CONFIG_ENS21X) += ens21x.o
 obj-$(CONFIG_HDC100X) += hdc100x.o
 obj-$(CONFIG_HDC2010) += hdc2010.o
 obj-$(CONFIG_HDC3020) += hdc3020.o
diff --git a/drivers/iio/humidity/ens21x.c b/drivers/iio/humidity/ens21x.c
new file mode 100644
index 000000000000..4145bb117c65
--- /dev/null
+++ b/drivers/iio/humidity/ens21x.c
@@ -0,0 +1,348 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * ens21x.c - Support for ScioSense ens21x
+ *           temperature & humidity sensor
+ *
+ * (7-bit I2C slave address 0x43 ENS210)
+ * (7-bit I2C slave address 0x43 ENS210A)
+ * (7-bit I2C slave address 0x44 ENS211)
+ * (7-bit I2C slave address 0x45 ENS212)
+ * (7-bit I2C slave address 0x46 ENS213A)
+ * (7-bit I2C slave address 0x47 ENS215)
+ *
+ * Datasheet:
+ *  https://www.sciosense.com/wp-content/uploads/2024/04/ENS21x-Datasheet.pdf
+ *  https://www.sciosense.com/wp-content/uploads/2023/12/ENS210-Datasheet.pdf
+ */
+
+#include <linux/types.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/crc7.h>
+
+/* register definitions */
+#define ENS21X_REG_PART_ID		0x00
+#define ENS21X_REG_DIE_REV		0x02
+#define ENS21X_REG_UID			0x04
+#define ENS21X_REG_SYS_CTRL		0x10
+#define ENS21X_REG_SYS_STAT		0x11
+#define ENS21X_REG_SENS_RUN		0x21
+#define ENS21X_REG_SENS_START		0x22
+#define ENS21X_REG_SENS_STOP		0x23
+#define ENS21X_REG_SENS_STAT		0x24
+#define ENS21X_REG_T_VAL		0x30
+#define ENS21X_REG_H_VAL		0x33
+
+/* value definitions */
+#define ENS21X_SENS_START_T_START		BIT(0)
+#define ENS21X_SENS_START_H_START		BIT(1)
+
+#define ENS21X_SENS_STAT_T_ACTIVE		BIT(0)
+#define ENS21X_SENS_STAT_H_ACTIVE		BIT(1)
+
+#define ENS21X_SYS_CTRL_LOW_POWER_ENABLE	BIT(0)
+#define ENS21X_SYS_CTRL_SYS_RESET		BIT(7)
+
+#define ENS21X_SYS_STAT_SYS_ACTIVE		BIT(0)
+
+/* magic constants */
+#define ENS21X_CONST_TEMP_SCALE_INT 15 /* integer part of temperature scale (1/64) */
+#define ENS21X_CONST_TEMP_SCALE_DEC 625000 /* decimal part of temperature scale */
+#define ENS21X_CONST_HUM_SCALE_INT 1 /* integer part of humidity scale (1/512) */
+#define ENS21X_CONST_HUM_SCALE_DEC 953125 /* decimal part of humidity scale */
+#define ENS21X_CONST_TEMP_OFFSET_INT -17481 /* temperature offset (64 * -273.15) */
+#define ENS21X_CONST_TEMP_OFFSET_DEC 600000 /* decimal part of offset */
+#define ENS210_CONST_CONVERSION_TIME 130
+#define ENS212_CONST_CONVERSION_TIME 32
+#define ENS215_CONST_CONVERSION_TIME 132
+
+static const struct of_device_id ens21x_of_match[];
+
+struct ens21x_dev {
+	struct i2c_client *client;
+	struct mutex lock;
+	int part_id;
+};
+
+enum ens21x_partnumber {
+	ENS210	= 0x0210,
+	ENS210A	= 0xa210,
+	ENS211	= 0x0211,
+	ENS212	= 0x0212,
+	ENS213A	= 0xa213,
+	ENS215	= 0x0215,
+};
+
+/* calculate 17-bit crc7 */
+static u8 ens21x_crc7(u32 val)
+{
+	u32 val_be = (htonl(val & 0x1ffff) >> 0x8);
+
+	return crc7_be(0xde, (u8 *)&val_be, 3) >> 1;
+}
+
+static int ens21x_get_measurement(struct iio_dev *indio_dev, bool temp, int *val)
+{
+	u32 regval, regval_le;
+	int ret, tries;
+	struct ens21x_dev *dev_data = iio_priv(indio_dev);
+
+	/* assert read */
+	i2c_smbus_write_byte_data(dev_data->client, ENS21X_REG_SENS_START,
+				  temp ? ENS21X_SENS_START_T_START :
+					 ENS21X_SENS_START_H_START);
+
+	/* wait for conversion to be ready */
+	switch (dev_data->part_id) {
+	case ENS210:
+	case ENS210A:
+		msleep(ENS210_CONST_CONVERSION_TIME);
+		break;
+	case ENS211:
+	case ENS212:
+		msleep(ENS212_CONST_CONVERSION_TIME);
+		break;
+	case ENS213A:
+	case ENS215:
+		msleep(ENS215_CONST_CONVERSION_TIME);
+		break;
+	default:
+		dev_err(&dev_data->client->dev, "unrecognised device");
+		return -ENODEV;
+	}
+
+	tries = 10;
+	while (tries-- > 0) {
+		usleep_range(4000, 5000);
+		ret = i2c_smbus_read_byte_data(dev_data->client,
+					       ENS21X_REG_SENS_STAT);
+		if (ret < 0)
+			continue;
+		if (!(ret & (temp ? ENS21X_SENS_STAT_T_ACTIVE :
+				    ENS21X_SENS_STAT_H_ACTIVE)))
+			break;
+	}
+	if (tries < 0) {
+		dev_err(&indio_dev->dev, "timeout waiting for sensor reading\n");
+		return -EIO;
+	}
+
+	/* perform read */
+	ret = i2c_smbus_read_i2c_block_data(
+		dev_data->client, temp ? ENS21X_REG_T_VAL : ENS21X_REG_H_VAL, 3,
+		(u8 *)&regval_le);
+	if (ret < 0) {
+		dev_err(&dev_data->client->dev, "failed to read register");
+		return -EIO;
+	} else if (ret == 3) {
+		regval = le32_to_cpu(regval_le);
+		if (ens21x_crc7(regval) == ((regval >> 17) & 0x7f)) {
+			*val = regval & 0xffff;
+			return IIO_VAL_INT;
+		}
+		/* crc fail */
+		dev_err(&indio_dev->dev, "ens invalid crc\n");
+		return -EIO;
+	}
+
+	dev_err(&indio_dev->dev, "expected 3 bytes, received %d\n", ret);
+	return -EIO;
+}
+
+static int ens21x_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *channel, int *val,
+			   int *val2, long mask)
+{
+	struct ens21x_dev *dev_data = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&dev_data->lock);
+		ret = ens21x_get_measurement(
+			indio_dev, channel->type == IIO_TEMP, val);
+		mutex_unlock(&dev_data->lock);
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		if (channel->type == IIO_TEMP) {
+			*val = ENS21X_CONST_TEMP_SCALE_INT;
+			*val2 = ENS21X_CONST_TEMP_SCALE_DEC;
+		} else {
+			*val = ENS21X_CONST_HUM_SCALE_INT;
+			*val2 = ENS21X_CONST_HUM_SCALE_DEC;
+		}
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+	case IIO_CHAN_INFO_OFFSET:
+		if (channel->type == IIO_TEMP) {
+			*val = ENS21X_CONST_TEMP_OFFSET_INT;
+			*val2 = ENS21X_CONST_TEMP_OFFSET_DEC;
+			ret = IIO_VAL_INT_PLUS_MICRO;
+			break;
+		}
+		*val = 0;
+		ret =  IIO_VAL_INT;
+		break;
+	default:
+		break;
+	}
+	return ret;
+}
+
+static const struct iio_chan_spec ens21x_channels[] = {
+	/* Temperature channel */
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_OFFSET),
+	},
+	/* Humidity channel */
+	{
+		.type = IIO_HUMIDITYRELATIVE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_OFFSET),
+	}
+};
+
+static const struct iio_info ens21x_info = {
+	.read_raw = ens21x_read_raw,
+};
+
+static const struct i2c_device_id ens21x_id[] = {
+	{"ens210", ENS210},
+	{"ens210a", ENS210A},
+	{"ens211", ENS211},
+	{"ens212", ENS212},
+	{"ens213a", ENS213A},
+	{"ens215", ENS215},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, ens21x_id);
+
+static int ens21x_probe(struct i2c_client *client)
+{
+	const struct i2c_device_id *id = i2c_client_get_device_id(client);
+	const struct of_device_id *match;
+	struct ens21x_dev *dev_data;
+	struct iio_dev *indio_dev;
+	uint16_t part_id_le, part_id;
+	int ret, tries;
+
+	if (!i2c_check_functionality(client->adapter,
+			I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
+			I2C_FUNC_SMBUS_WRITE_BYTE |
+			I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+		dev_err(&client->dev,
+			"adapter does not support some i2c transactions\n");
+		return -EOPNOTSUPP;
+	}
+
+	match = of_match_device(ens21x_of_match, &client->dev);
+	if (!match) {
+		dev_err(&client->dev, "failed to get match data\n");
+		return -ENODEV;
+	}
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*dev_data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	dev_data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	dev_data->client = client;
+	mutex_init(&dev_data->lock);
+
+	/* reset device */
+	ret = i2c_smbus_write_byte_data(client, ENS21X_REG_SYS_CTRL,
+					ENS21X_SYS_CTRL_SYS_RESET);
+	if (ret)
+		return ret;
+
+	/* wait for device to become active */
+	usleep_range(4000, 5000);
+
+	/* disable low power mode */
+	ret = i2c_smbus_write_byte_data(client, ENS21X_REG_SYS_CTRL, 0x00);
+	if (ret)
+		return ret;
+
+	/* wait for device to become active */
+	tries = 10;
+	while (tries-- > 0) {
+		msleep(20);
+		ret = i2c_smbus_read_byte_data(client, ENS21X_REG_SYS_STAT);
+		if (ret < 0)
+			return ret;
+		if (ret & ENS21X_SYS_STAT_SYS_ACTIVE)
+			break;
+	}
+	if (tries < 0) {
+		dev_err(&client->dev,
+			"timeout waiting for ens21x to become active\n");
+		return -EIO;
+	}
+
+	/* get part_id */
+	part_id_le = i2c_smbus_read_word_data(client, ENS21X_REG_PART_ID);
+	if (part_id_le < 0)
+		return part_id_le;
+	part_id = le16_to_cpu(part_id_le);
+
+	if (part_id != id->driver_data) {
+		dev_err(&client->dev,
+			"Part ID does not match (0x%04x != 0x%04lx)\n", part_id,
+			id->driver_data);
+		return -ENODEV;
+	}
+
+	/* reenable low power */
+	ret = i2c_smbus_write_byte_data(client, ENS21X_REG_SYS_CTRL,
+					ENS21X_SYS_CTRL_LOW_POWER_ENABLE);
+	if (ret)
+		return ret;
+
+	dev_data->part_id = part_id;
+
+	indio_dev->name = id->name;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = ens21x_channels;
+	indio_dev->num_channels = ARRAY_SIZE(ens21x_channels);
+	indio_dev->info = &ens21x_info;
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+
+static const struct of_device_id ens21x_of_match[] = {
+	{ .compatible = "sciosense,ens210" },
+	{ .compatible = "sciosense,ens210a" },
+	{ .compatible = "sciosense,ens211" },
+	{ .compatible = "sciosense,ens212" },
+	{ .compatible = "sciosense,ens213a" },
+	{ .compatible = "sciosense,ens215" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ens21x_of_match);
+
+static struct i2c_driver ens21x_driver = {
+	.probe = ens21x_probe,
+	.id_table = ens21x_id,
+	.driver = {
+		.name = "ens21x",
+		.of_match_table = ens21x_of_match,
+	},
+};
+
+module_i2c_driver(ens21x_driver);
+
+MODULE_DESCRIPTION("ScioSense ENS21x temperature and humidity sensor driver");
+MODULE_AUTHOR("Joshua Felmeden <jfelmeden@thegoodpenguin.co.uk>");
+MODULE_LICENSE("GPL");
+

-- 
2.39.2

Re: [PATCH 1/2] dt-bindings: iio: humidity: add ENS21x sensor family

[Krzysztof Kozlowski]

On 09/07/2024 18:36, Joshua Felmeden wrote:
> Add device tree documentation for ENS21x family of temperature and
> humidity sensors
> 
> Signed-off-by: Joshua Felmeden <jfelmeden@thegoodpenguin.co.uk>


I believe that's either RESEND or v2, so you are supposed to mark it in
patch prefix accordingly. If it is v2, then provide also changelog under
--- or in cover letter.

> ---
>  .../bindings/iio/humidity/sciosense,ens21x.yaml    | 50 ++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/humidity/sciosense,ens21x.yaml b/Documentation/devicetree/bindings/iio/humidity/sciosense,ens21x.yaml
> new file mode 100644
> index 000000000000..3140349a58b8
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/humidity/sciosense,ens21x.yaml
> @@ -0,0 +1,50 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/humidity/sciosense,ens21x.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: ScioSense ENS21x temperature and humidity sensor
> +
> +maintainers:
> +  - Joshua Felmeden <jfelmeden@thegoodpenguin.co.uk>
> +
> +description: |
> +  Temperature and Humidity sensor.
> +
> +  Datasheet:
> +    https://www.sciosense.com/wp-content/uploads/2024/04/ENS21x-Datasheet.pdf
> +    https://www.sciosense.com/wp-content/uploads/2023/12/ENS210-Datasheet.pdf
> +
> +properties:
> +  compatible:
> +    enum:
> +      - sciosense,ens210
> +      - sciosense,ens210a
> +      - sciosense,ens211
> +      - sciosense,ens212
> +      - sciosense,ens213a
> +      - sciosense,ens215

Driver suggests these are compatible, so I would normally expect using
one as fallback for others.

> +
> +  reg:
> +    maxItems: 1
> +

Missing supply.

> +required:
> +  - compatible
> +  - reg
> +
> +unevaluatedProperties: false

This must be additionalProperties instead.

Best regards,
Krzysztof

Re: [PATCH 2/2] iio: humidity: Add support for ENS21x

[Krzysztof Kozlowski]

On 09/07/2024 18:36, Joshua Felmeden wrote:
> Add support for ENS210/ENS210A/ENS211/ENS212/ENS213A/ENS215.
> 
> The ENS21x is a family of temperature and relative humidity sensors with
> accuracies tailored to the needs of specific applications.
> 
> Signed-off-by: Joshua Felmeden <jfelmeden@thegoodpenguin.co.uk>
> ---
>  drivers/iio/humidity/Kconfig  |  11 ++
>  drivers/iio/humidity/Makefile |   1 +
>  drivers/iio/humidity/ens21x.c | 348 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 360 insertions(+)
> 


> +
> +static int ens21x_probe(struct i2c_client *client)
> +{
> +	const struct i2c_device_id *id = i2c_client_get_device_id(client);
> +	const struct of_device_id *match;
> +	struct ens21x_dev *dev_data;
> +	struct iio_dev *indio_dev;
> +	uint16_t part_id_le, part_id;
> +	int ret, tries;
> +
> +	if (!i2c_check_functionality(client->adapter,
> +			I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
> +			I2C_FUNC_SMBUS_WRITE_BYTE |
> +			I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
> +		dev_err(&client->dev,
> +			"adapter does not support some i2c transactions\n");
> +		return -EOPNOTSUPP;
> +	}
> +
> +	match = of_match_device(ens21x_of_match, &client->dev);
> +	if (!match) {
> +		dev_err(&client->dev, "failed to get match data\n");

That's odd. This should never happen, so printing error suggests
something is odd in your driver.

There is anyway helper for getting match data from i2c/of cases.


> +		return -ENODEV;
> +	}
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*dev_data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	dev_data = iio_priv(indio_dev);
> +	i2c_set_clientdata(client, indio_dev);
> +	dev_data->client = client;
> +	mutex_init(&dev_data->lock);
> +
> +	/* reset device */
> +	ret = i2c_smbus_write_byte_data(client, ENS21X_REG_SYS_CTRL,
> +					ENS21X_SYS_CTRL_SYS_RESET);
> +	if (ret)
> +		return ret;
> +
> +	/* wait for device to become active */
> +	usleep_range(4000, 5000);
> +
> +	/* disable low power mode */
> +	ret = i2c_smbus_write_byte_data(client, ENS21X_REG_SYS_CTRL, 0x00);
> +	if (ret)
> +		return ret;
> +
> +	/* wait for device to become active */
> +	tries = 10;
> +	while (tries-- > 0) {
> +		msleep(20);
> +		ret = i2c_smbus_read_byte_data(client, ENS21X_REG_SYS_STAT);
> +		if (ret < 0)
> +			return ret;
> +		if (ret & ENS21X_SYS_STAT_SYS_ACTIVE)
> +			break;
> +	}
> +	if (tries < 0) {
> +		dev_err(&client->dev,
> +			"timeout waiting for ens21x to become active\n");
> +		return -EIO;
> +	}
> +
> +	/* get part_id */
> +	part_id_le = i2c_smbus_read_word_data(client, ENS21X_REG_PART_ID);
> +	if (part_id_le < 0)
> +		return part_id_le;
> +	part_id = le16_to_cpu(part_id_le);
> +
> +	if (part_id != id->driver_data) {
> +		dev_err(&client->dev,
> +			"Part ID does not match (0x%04x != 0x%04lx)\n", part_id,
> +			id->driver_data);
> +		return -ENODEV;
> +	}
> +
> +	/* reenable low power */
> +	ret = i2c_smbus_write_byte_data(client, ENS21X_REG_SYS_CTRL,
> +					ENS21X_SYS_CTRL_LOW_POWER_ENABLE);
> +	if (ret)
> +		return ret;
> +
> +	dev_data->part_id = part_id;
> +
> +	indio_dev->name = id->name;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = ens21x_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(ens21x_channels);
> +	indio_dev->info = &ens21x_info;
> +
> +	return devm_iio_device_register(&client->dev, indio_dev);
> +}
> +
> +
> +static const struct of_device_id ens21x_of_match[] = {
> +	{ .compatible = "sciosense,ens210" },
> +	{ .compatible = "sciosense,ens210a" },
> +	{ .compatible = "sciosense,ens211" },
> +	{ .compatible = "sciosense,ens212" },
> +	{ .compatible = "sciosense,ens213a" },
> +	{ .compatible = "sciosense,ens215" },

Mismathed with i2c_device_id. These should have the same data. Also,
keep the tables next to each other (here).



Best regards,
Krzysztof