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The device is accessed over I2C and reports differential pressure and temperature. Each measurement is validated using the sensor's CRC-8 checksum. Tested on an SDP31 connected to a Raspberry Pi 4 I2C bus. Signed-off-by: Muhammad Abu Bakar --- MAINTAINERS | 6 ++ drivers/iio/pressure/Kconfig | 11 ++ drivers/iio/pressure/Makefile | 1 + drivers/iio/pressure/sdp31.c | 194 ++++++++++++++++++++++++++++++++++ 4 files changed, 212 insertions(+) create mode 100644 drivers/iio/pressure/sdp31.c diff --git a/MAINTAINERS b/MAINTAINERS index 214aeee76..a053a530e 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -24855,6 +24855,12 @@ S: Maintained F: Documentation/devicetree/bindings/iio/chemical/sensirion,scd4x.yaml F: drivers/iio/chemical/scd4x.c +SENSIRION SDP31 DIFFERENTIAL PRESSURE SENSOR DRIVER +M: Muhammad Abu Bakar +S: Maintained +F: Documentation/devicetree/bindings/iio/pressure/sensirion,sdp31.yaml +F: drivers/iio/pressure/sdp31.c + SENSIRION SDP500 DIFFERENTIAL PRESSURE SENSOR DRIVER M: Petar Stoykov S: Maintained diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig index 838a8340c..58172639c 100644 --- a/drivers/iio/pressure/Kconfig +++ b/drivers/iio/pressure/Kconfig @@ -286,6 +286,17 @@ config MS5637 This driver can also be built as a module. If so, the module will be called ms5637. +config SDP31 + tristate "Sensirion SDP31 differential pressure sensor I2C driver" + depends on I2C + select CRC8 + help + Say Y here to build support for Sensirion SDP31 differential pressure + sensor I2C driver. + + To compile this driver as a module, choose M here: the core module + will be called sdp31. + config SDP500 tristate "Sensirion SDP500 differential pressure sensor I2C driver" depends on I2C diff --git a/drivers/iio/pressure/Makefile b/drivers/iio/pressure/Makefile index bc0d11a20..5279a0ebd 100644 --- a/drivers/iio/pressure/Makefile +++ b/drivers/iio/pressure/Makefile @@ -35,6 +35,7 @@ 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-$(CONFIG_SDP31) += sdp31.o obj-$(CONFIG_SDP500) += sdp500.o obj-$(CONFIG_IIO_ST_PRESS) += st_pressure.o st_pressure-y := st_pressure_core.o diff --git a/drivers/iio/pressure/sdp31.c b/drivers/iio/pressure/sdp31.c new file mode 100644 index 000000000..934a3afcd --- /dev/null +++ b/drivers/iio/pressure/sdp31.c @@ -0,0 +1,194 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +#include +#include +#include +#include +#include +#include + +#define SDP31_CMD_TRIG_DP 0x362F +#define SDP31_MEAS_DELAY_MS 50 +#define SDP31_TEMP_SCALE 5 +#define SDP31_CRC8_POLY 0x31 +#define SDP31_CRC8_INIT 0xff + +DECLARE_CRC8_TABLE(sdp31_crc8_table); + +struct sdp31_data { + struct i2c_client *client; + struct mutex lock; /* serializes multi-step measurements */ + u16 dp_scale; /* diff-pressure scale factor read from the sensor */ +}; + +struct sdp31_reading { + s16 pressure; + s16 temp; + u16 scale; +}; + +static int sdp31_send_cmd(struct i2c_client *client, u16 cmd) +{ + u8 buf[2] = { cmd >> 8, cmd & 0xff }; + int ret = i2c_master_send(client, buf, sizeof(buf)); + + if (ret < 0) + return ret; + return (ret == sizeof(buf)) ? 0 : -EIO; +} + +static int sdp31_check_crc(const u8 *word) +{ + if (crc8(sdp31_crc8_table, word, 2, SDP31_CRC8_INIT) != word[2]) + return -EIO; + return 0; +} + +static int sdp31_measure(struct i2c_client *client, struct sdp31_reading *out) +{ + u8 rx[9]; + int ret; + + ret = sdp31_send_cmd(client, SDP31_CMD_TRIG_DP); + if (ret) + return ret; + + msleep(SDP31_MEAS_DELAY_MS); + + ret = i2c_master_recv(client, rx, sizeof(rx)); + if (ret < 0) + return ret; + if (ret != sizeof(rx)) + return -EIO; + + if (sdp31_check_crc(&rx[0]) || + sdp31_check_crc(&rx[3]) || + sdp31_check_crc(&rx[6])) + return -EIO; + + out->pressure = (s16)((rx[0] << 8) | rx[1]); + out->temp = (s16)((rx[3] << 8) | rx[4]); + out->scale = (rx[6] << 8) | rx[7]; + return 0; +} + +static int sdp31_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct sdp31_data *data = iio_priv(indio_dev); + struct sdp31_reading r; + int ret; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + mutex_lock(&data->lock); + ret = sdp31_measure(data->client, &r); + mutex_unlock(&data->lock); + if (ret) + return ret; + switch (chan->type) { + case IIO_PRESSURE: + *val = r.pressure; + return IIO_VAL_INT; + case IIO_TEMP: + *val = r.temp; + return IIO_VAL_INT; + default: + return -EINVAL; + } + case IIO_CHAN_INFO_SCALE: + switch (chan->type) { + case IIO_PRESSURE: + /* raw / dp_scale = Pa; /1000 => kPa (IIO unit) */ + *val = 1; + *val2 = data->dp_scale * 1000; + return IIO_VAL_FRACTIONAL; + case IIO_TEMP: + *val = SDP31_TEMP_SCALE; + return IIO_VAL_INT; + default: + return -EINVAL; + } + default: + return -EINVAL; + } +} + +static const struct iio_info sdp31_info = { + .read_raw = sdp31_read_raw, +}; + +static const struct iio_chan_spec sdp31_channels[] = { + { + .type = IIO_PRESSURE, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | + BIT(IIO_CHAN_INFO_SCALE), + }, + { + .type = IIO_TEMP, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | + BIT(IIO_CHAN_INFO_SCALE), + }, +}; + +static int sdp31_probe(struct i2c_client *client) +{ + struct iio_dev *indio_dev; + struct sdp31_data *data; + struct sdp31_reading r; + int ret; + + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); + if (!indio_dev) + return -ENOMEM; + + data = iio_priv(indio_dev); + data->client = client; + mutex_init(&data->lock); + + crc8_populate_msb(sdp31_crc8_table, SDP31_CRC8_POLY); + + /* Confirm the sensor is present and learn its scale factor. */ + ret = sdp31_measure(client, &r); + if (ret) + return dev_err_probe(&client->dev, ret, + "failed to read from sensor\n"); + if (!r.scale) + return dev_err_probe(&client->dev, -EINVAL, + "invalid scale factor\n"); + data->dp_scale = r.scale; + + indio_dev->name = "sdp31"; + indio_dev->info = &sdp31_info; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = sdp31_channels; + indio_dev->num_channels = ARRAY_SIZE(sdp31_channels); + + return devm_iio_device_register(&client->dev, indio_dev); +} + +static const struct i2c_device_id sdp31_id[] = { + { "sdp31" }, + { } +}; +MODULE_DEVICE_TABLE(i2c, sdp31_id); + +static const struct of_device_id sdp31_of_match[] = { + { .compatible = "sensirion,sdp31" }, + { } +}; +MODULE_DEVICE_TABLE(of, sdp31_of_match); + +static struct i2c_driver sdp31_driver = { + .driver = { + .name = "sdp31", + .of_match_table = sdp31_of_match, + }, + .probe = sdp31_probe, + .id_table = sdp31_id, +}; +module_i2c_driver(sdp31_driver); + +MODULE_AUTHOR("Muhammad Abu Bakar"); +MODULE_DESCRIPTION("Sensirion SDP31 differential pressure sensor"); +MODULE_LICENSE("GPL"); -- 2.43.0