[PATCH v2 2/3] iio: pressure: Add driver for Sensirion SDP500

Petar Stoykov
2024-04-30T15:27:36Z

From 6ae7537517f551540121ca6fb3b99080b7580410 Mon Sep 17 00:00:00 2001
From: Petar Stoykov <pd.pstoykov@gmail.com>
Date: Mon, 15 Jan 2024 12:21:26 +0100
Subject: [PATCH 2/3] 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>
---
drivers/iio/pressure/Kconfig | 9 +++
drivers/iio/pressure/Makefile | 1 +
drivers/iio/pressure/sdp500.c | 144 ++++++++++++++++++++++++++++++++++
3 files changed, 154 insertions(+)
create mode 100644 drivers/iio/pressure/sdp500.c

diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
index 95efa32e4289..5debdfbd5324 100644
--- a/drivers/iio/pressure/Kconfig
+++ b/drivers/iio/pressure/Kconfig
@@ -212,6 +212,15 @@ 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
diff --git a/drivers/iio/pressure/Makefile b/drivers/iio/pressure/Makefile
index 436aec7e65f3..489ef7b7befa 100644
--- a/drivers/iio/pressure/Makefile
+++ b/drivers/iio/pressure/Makefile
@@ -25,6 +25,7 @@ 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
diff --git a/drivers/iio/pressure/sdp500.c b/drivers/iio/pressure/sdp500.c
new file mode 100644
index 000000000000..7efcc69e829c
--- /dev/null
+++ b/drivers/iio/pressure/sdp500.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/i2c.h>
+#include <linux/crc8.h>
+#include <linux/iio/iio.h>
+#include <asm/unaligned.h>
+
+#define SDP500_CRC8_POLYNOMIAL 0x31 // x8 + x5 + x4 + 1 (normalized to 0x31)
+#define SDP500_READ_SIZE 3
+#define SDP500_CRC8_WORD_LENGTH 2
+#define SDP500_CRC8_INIT 0x00
+
+#define SDP500_SCALE_FACTOR 60
+
+#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, const
struct iio_dev *indio_dev)
+{
+ 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_PROCESSED),
+ },
+};
+
+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 rec_crc, calculated_crc;
+ s16 dec_value;
+ struct sdp500_data *data = iio_priv(indio_dev);
+ struct i2c_client *client = to_i2c_client(data->dev);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_PROCESSED:
+ ret = i2c_master_recv(client, rxbuf, SDP500_READ_SIZE);
+ if (ret < 0) {
+ dev_err(indio_dev->dev.parent, "Failed to receive data");
+ return ret;
+ }
+ if (ret != SDP500_READ_SIZE) {
+ dev_err(indio_dev->dev.parent, "Data is received wrongly");
+ return -EIO;
+ }
+
+ rec_crc = rxbuf[2];
+ calculated_crc = crc8(sdp500_crc8_table, rxbuf,
SDP500_CRC8_WORD_LENGTH,
+ SDP500_CRC8_INIT);
+ if (rec_crc != calculated_crc) {
+ dev_err(indio_dev->dev.parent, "calculated crc = 0x%.2X,
received 0x%.2X",
+ calculated_crc, rec_crc);
+ return -EIO;
+ }
+
+ dec_value = get_unaligned_be16(rxbuf);
+ dev_dbg(indio_dev->dev.parent, "dec value = %d", dec_value);
+
+ *val = dec_value;
+ *val2 = SDP500_SCALE_FACTOR;
+ 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];
+
+ 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, indio_dev);
+ 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 < 0)
+ 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");
--
2.30.2