iio: pressure: Add driver for Sensirion SDP500

Sensirion SDP500 is a digital differential pressure sensor. The sensor is
accessed over I2C.

Signed-off-by: Petar Stoykov <pd.pstoykov@gmail.com>
Link: https://patch.msgid.link/20240725-mainline_sdp500-v4-2-ea2f5b189958@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/pressure/Kconfig

@@ -250,6 +250,15 @@ config MS5637
 	  This driver can also be built as a module. If so, the module will
 	  be called ms5637.
 
+config SDP500
+	tristate "Sensirion SDP500 differential pressure sensor I2C driver"
+	depends on I2C
+	help
+	  Say Y here to build support for Sensirion SDP500 differential pressure
+	  sensor I2C driver.
+	  To compile this driver as a module, choose M here: the core module
+	  will be called sdp500.
+
 config IIO_ST_PRESS
 	tristate "STMicroelectronics pressure sensor Driver"
 	depends on (I2C || SPI_MASTER) && SYSFS

drivers/iio/pressure/Makefile

@@ -30,6 +30,7 @@ obj-$(CONFIG_MS5611) += ms5611_core.o
 obj-$(CONFIG_MS5611_I2C) += ms5611_i2c.o
 obj-$(CONFIG_MS5611_SPI) += ms5611_spi.o
 obj-$(CONFIG_MS5637) += ms5637.o
+obj-$(CONFIG_SDP500) += sdp500.o
 obj-$(CONFIG_IIO_ST_PRESS) += st_pressure.o
 st_pressure-y := st_pressure_core.o
 st_pressure-$(CONFIG_IIO_BUFFER) += st_pressure_buffer.o

drivers/iio/pressure/sdp500.c

@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for Sensirion sdp500 and sdp510 pressure sensors
+ *
+ * Datasheet: https://sensirion.com/resource/datasheet/sdp600
+ */
+
+#include <linux/i2c.h>
+#include <linux/crc8.h>
+#include <linux/iio/iio.h>
+#include <linux/mod_devicetable.h>
+#include <linux/regulator/consumer.h>
+#include <asm/unaligned.h>
+
+#define SDP500_CRC8_POLYNOMIAL  0x31   /* x8+x5+x4+1 (normalized to 0x31) */
+#define SDP500_READ_SIZE        3
+
+#define SDP500_I2C_START_MEAS 0xF1
+
+struct sdp500_data {
+	struct device *dev;
+};
+
+DECLARE_CRC8_TABLE(sdp500_crc8_table);
+
+static int sdp500_start_measurement(struct sdp500_data *data)
+{
+	struct i2c_client *client = to_i2c_client(data->dev);
+
+	return i2c_smbus_write_byte(client, SDP500_I2C_START_MEAS);
+}
+
+static const struct iio_chan_spec sdp500_channels[] = {
+	{
+		.type = IIO_PRESSURE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE),
+	},
+};
+
+static int sdp500_read_raw(struct iio_dev *indio_dev,
+			  struct iio_chan_spec const *chan,
+			  int *val, int *val2, long mask)
+{
+	int ret;
+	u8 rxbuf[SDP500_READ_SIZE];
+	u8 received_crc, calculated_crc;
+	struct sdp500_data *data = iio_priv(indio_dev);
+	struct i2c_client *client = to_i2c_client(data->dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = i2c_master_recv(client, rxbuf, SDP500_READ_SIZE);
+		if (ret < 0) {
+			dev_err(data->dev, "Failed to receive data");
+			return ret;
+		}
+		if (ret != SDP500_READ_SIZE) {
+			dev_err(data->dev, "Data is received wrongly");
+			return -EIO;
+		}
+
+		received_crc = rxbuf[2];
+		calculated_crc = crc8(sdp500_crc8_table, rxbuf,
+				      sizeof(rxbuf) - 1, 0x00);
+		if (received_crc != calculated_crc) {
+			dev_err(data->dev,
+				"calculated crc = 0x%.2X, received 0x%.2X",
+				calculated_crc, received_crc);
+			return -EIO;
+		}
+
+		*val = get_unaligned_be16(rxbuf);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 1;
+		*val2 = 60;
+
+		return IIO_VAL_FRACTIONAL;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info sdp500_info = {
+	.read_raw = &sdp500_read_raw,
+};
+
+static int sdp500_probe(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev;
+	struct sdp500_data *data;
+	struct device *dev = &client->dev;
+	int ret;
+	u8 rxbuf[SDP500_READ_SIZE];
+
+	ret = devm_regulator_get_enable(dev, "vdd");
+	if (ret)
+		return dev_err_probe(dev, ret,
+			"Failed to get and enable regulator\n");
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	/* has to be done before the first i2c communication */
+	crc8_populate_msb(sdp500_crc8_table, SDP500_CRC8_POLYNOMIAL);
+
+	data = iio_priv(indio_dev);
+	data->dev = dev;
+
+	indio_dev->name = "sdp500";
+	indio_dev->channels = sdp500_channels;
+	indio_dev->info = &sdp500_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->num_channels = ARRAY_SIZE(sdp500_channels);
+
+	ret = sdp500_start_measurement(data);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to start measurement");
+
+	/* First measurement is not correct, read it out to get rid of it */
+	i2c_master_recv(client, rxbuf, SDP500_READ_SIZE);
+
+	ret = devm_iio_device_register(dev, indio_dev);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to register indio_dev");
+
+	return 0;
+}
+
+static const struct i2c_device_id sdp500_id[] = {
+	{ "sdp500" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, sdp500_id);
+
+static const struct of_device_id sdp500_of_match[] = {
+	{ .compatible = "sensirion,sdp500" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sdp500_of_match);
+
+static struct i2c_driver sdp500_driver = {
+	.driver = {
+		.name = "sensirion,sdp500",
+		.of_match_table = sdp500_of_match,
+	},
+	.probe = sdp500_probe,
+	.id_table = sdp500_id,
+};
+module_i2c_driver(sdp500_driver);
+
+MODULE_AUTHOR("Thomas Sioutas <thomas.sioutas@prodrive-technologies.com>");
+MODULE_DESCRIPTION("Driver for Sensirion SDP500 differential pressure sensor");
+MODULE_LICENSE("GPL");