[PATCH v3 2/2] iio: humidity: Add support for ENS21x

From: Joshua Felmeden
Date: Wed Jul 10 2024 - 09:24:38 EST

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@xxxxxxxxxxxxxxxxxxxx>
---
drivers/iio/humidity/Kconfig | 11 ++
drivers/iio/humidity/Makefile | 1 +
drivers/iio/humidity/ens21x.c | 346 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 358 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..7b2e279d1559
--- /dev/null
+++ b/drivers/iio/humidity/ens21x.c
@@ -0,0 +1,346 @@
+// 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 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 = i2c_of_match_device(ens21x_of_match, client);
+ if (!match)
+ 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", .data = (void *)ENS210},
+ { .compatible = "sciosense,ens210a", .data = (void *)ENS210A },
+ { .compatible = "sciosense,ens211", .data = (void *)ENS211},
+ { .compatible = "sciosense,ens212", .data = (void *)ENS212},
+ { .compatible = "sciosense,ens213a", .data = (void *)ENS213A },
+ { .compatible = "sciosense,ens215", .data = (void *)ENS215},
+ {},
+};
+MODULE_DEVICE_TABLE(of, ens21x_of_match);
+
+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 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@xxxxxxxxxxxxxxxxxxxx>");
+MODULE_LICENSE("GPL");
+

--
2.39.2