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drivers: iio: chemical: Add support for Sensirion SCD4x CO2 sensor

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This is a driver for the SCD4x CO2 sensor from Sensirion. The sensor is
able to measure CO2 concentration, temperature and relative humdity.
The sensor uses a photoacoustic principle for measuring CO2 concentration.
An I2C interface is supported by this driver in order to communicate with
the sensor.

Signed-off-by: Roan van Dijk <roan@protonic.nl>
Link: https://lore.kernel.org/r/20211008101706.755942-4-roan@protonic.nl
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Roan van Dijk 2021-10-08 12:17:05 +02:00 committed by Jonathan Cameron
parent 2be47f8d62
commit 49d22b695c
3 changed files with 705 additions and 0 deletions
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13
drivers/iio/chemical/Kconfig
View File

@ -118,6 +118,19 @@ config SCD30_SERIAL
To compile this driver as a module, choose M here: the module will
be called scd30_serial.
config SCD4X
tristate "SCD4X carbon dioxide sensor driver"
select IIO_BUFFER
select IIO_TRIGGERED_BUFFER
depends on I2C
select CRC8
help
Say Y here to build support for the Sensirion SCD4X sensor with carbon
dioxide, relative humidity and temperature sensing capabilities.
To compile this driver as a module, choose M here: the module will
be called scd4x.
config SENSIRION_SGP30
tristate "Sensirion SGPxx gas sensors"
depends on I2C

1
drivers/iio/chemical/Makefile
View File

@ -15,6 +15,7 @@ obj-$(CONFIG_PMS7003) += pms7003.o
obj-$(CONFIG_SCD30_CORE) += scd30_core.o
obj-$(CONFIG_SCD30_I2C) += scd30_i2c.o
obj-$(CONFIG_SCD30_SERIAL) += scd30_serial.o
obj-$(CONFIG_SCD4X) += scd4x.o
obj-$(CONFIG_SENSEAIR_SUNRISE_CO2) += sunrise_co2.o
obj-$(CONFIG_SENSIRION_SGP30) += sgp30.o
obj-$(CONFIG_SENSIRION_SGP40) += sgp40.o

691
drivers/iio/chemical/scd4x.c Normal file
View File

@ -0,0 +1,691 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Sensirion SCD4X carbon dioxide sensor i2c driver
*
* Copyright (C) 2021 Protonic Holland
* Author: Roan van Dijk <roan@protonic.nl>
*
* I2C slave address: 0x62
*
* Datasheets:
* https://www.sensirion.com/file/datasheet_scd4x
*/
#include <asm/unaligned.h>
#include <linux/crc8.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/i2c.h>
#include <linux/iio/buffer.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/trigger.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/types.h>
#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include <linux/types.h>
#define SCD4X_CRC8_POLYNOMIAL 0x31
#define SCD4X_TIMEOUT_ERR 1000
#define SCD4X_READ_BUF_SIZE 9
#define SCD4X_COMMAND_BUF_SIZE 2
#define SCD4X_WRITE_BUF_SIZE 5
#define SCD4X_FRC_MIN_PPM 0
#define SCD4X_FRC_MAX_PPM 2000
#define SCD4X_READY_MASK 0x01
/*Commands SCD4X*/
enum scd4x_cmd {
CMD_START_MEAS = 0x21b1,
CMD_READ_MEAS = 0xec05,
CMD_STOP_MEAS = 0x3f86,
CMD_SET_TEMP_OFFSET = 0x241d,
CMD_GET_TEMP_OFFSET = 0x2318,
CMD_FRC = 0x362f,
CMD_SET_ASC = 0x2416,
CMD_GET_ASC = 0x2313,
CMD_GET_DATA_READY = 0xe4b8,
};
enum scd4x_channel_idx {
SCD4X_CO2,
SCD4X_TEMP,
SCD4X_HR,
};
struct scd4x_state {
struct i2c_client *client;
/* maintain access to device, to prevent concurrent reads/writes */
struct mutex lock;
struct regulator *vdd;
};
DECLARE_CRC8_TABLE(scd4x_crc8_table);
static int scd4x_i2c_xfer(struct scd4x_state *state, char *txbuf, int txsize,
char *rxbuf, int rxsize)
{
struct i2c_client *client = state->client;
int ret;
ret = i2c_master_send(client, txbuf, txsize);
if (ret < 0)
return ret;
if (ret != txsize)
return -EIO;
if (rxsize == 0)
return 0;
ret = i2c_master_recv(client, rxbuf, rxsize);
if (ret < 0)
return ret;
if (ret != rxsize)
return -EIO;
return 0;
}
static int scd4x_send_command(struct scd4x_state *state, enum scd4x_cmd cmd)
{
char buf[SCD4X_COMMAND_BUF_SIZE];
int ret;
/*
* Measurement needs to be stopped before sending commands.
* Except stop and start command.
*/
if ((cmd != CMD_STOP_MEAS) && (cmd != CMD_START_MEAS)) {
ret = scd4x_send_command(state, CMD_STOP_MEAS);
if (ret)
return ret;
/* execution time for stopping measurement */
msleep_interruptible(500);
}
put_unaligned_be16(cmd, buf);
ret = scd4x_i2c_xfer(state, buf, 2, buf, 0);
if (ret)
return ret;
if ((cmd != CMD_STOP_MEAS) && (cmd != CMD_START_MEAS)) {
ret = scd4x_send_command(state, CMD_START_MEAS);
if (ret)
return ret;
}
return 0;
}
static int scd4x_read(struct scd4x_state *state, enum scd4x_cmd cmd,
void *response, int response_sz)
{
struct i2c_client *client = state->client;
char buf[SCD4X_READ_BUF_SIZE];
char *rsp = response;
int i, ret;
char crc;
/*
* Measurement needs to be stopped before sending commands.
* Except for reading measurement and data ready command.
*/
if ((cmd != CMD_GET_DATA_READY) && (cmd != CMD_READ_MEAS)) {
ret = scd4x_send_command(state, CMD_STOP_MEAS);
if (ret)
return ret;
/* execution time for stopping measurement */
msleep_interruptible(500);
}
/* CRC byte for every 2 bytes of data */
response_sz += response_sz / 2;
put_unaligned_be16(cmd, buf);
ret = scd4x_i2c_xfer(state, buf, 2, buf, response_sz);
if (ret)
return ret;
for (i = 0; i < response_sz; i += 3) {
crc = crc8(scd4x_crc8_table, buf + i, 2, CRC8_INIT_VALUE);
if (crc != buf[i + 2]) {
dev_err(&client->dev, "CRC error\n");
return -EIO;
}
*rsp++ = buf[i];
*rsp++ = buf[i + 1];
}
/* start measurement */
if ((cmd != CMD_GET_DATA_READY) && (cmd != CMD_READ_MEAS)) {
ret = scd4x_send_command(state, CMD_START_MEAS);
if (ret)
return ret;
}
return 0;
}
static int scd4x_write(struct scd4x_state *state, enum scd4x_cmd cmd, uint16_t arg)
{
char buf[SCD4X_WRITE_BUF_SIZE];
int ret;
char crc;
put_unaligned_be16(cmd, buf);
put_unaligned_be16(arg, buf + 2);
crc = crc8(scd4x_crc8_table, buf + 2, 2, CRC8_INIT_VALUE);
buf[4] = crc;
/* measurement needs to be stopped before sending commands */
ret = scd4x_send_command(state, CMD_STOP_MEAS);
if (ret)
return ret;
/* execution time */
msleep_interruptible(500);
ret = scd4x_i2c_xfer(state, buf, SCD4X_WRITE_BUF_SIZE, buf, 0);
if (ret)
return ret;
/* start measurement, except for forced calibration command */
if (cmd != CMD_FRC) {
ret = scd4x_send_command(state, CMD_START_MEAS);
if (ret)
return ret;
}
return 0;
}
static int scd4x_write_and_fetch(struct scd4x_state *state, enum scd4x_cmd cmd,
uint16_t arg, void *response, int response_sz)
{
struct i2c_client *client = state->client;
char buf[SCD4X_READ_BUF_SIZE];
char *rsp = response;
int i, ret;
char crc;
ret = scd4x_write(state, CMD_FRC, arg);
if (ret)
goto err;
/* execution time */
msleep_interruptible(400);
/* CRC byte for every 2 bytes of data */
response_sz += response_sz / 2;
ret = i2c_master_recv(client, buf, response_sz);
if (ret < 0)
goto err;
if (ret != response_sz) {
ret = -EIO;
goto err;
}
for (i = 0; i < response_sz; i += 3) {
crc = crc8(scd4x_crc8_table, buf + i, 2, CRC8_INIT_VALUE);
if (crc != buf[i + 2]) {
dev_err(&client->dev, "CRC error\n");
ret = -EIO;
goto err;
}
*rsp++ = buf[i];
*rsp++ = buf[i + 1];
}
return scd4x_send_command(state, CMD_START_MEAS);
err:
/*
* on error try to start the measurement,
* puts sensor back into continuous measurement
*/
scd4x_send_command(state, CMD_START_MEAS);
return ret;
}
static int scd4x_read_meas(struct scd4x_state *state, uint16_t *meas)
{
int i, ret;
__be16 buf[3];
ret = scd4x_read(state, CMD_READ_MEAS, buf, sizeof(buf));
if (ret)
return ret;
for (i = 0; i < ARRAY_SIZE(buf); i++)
meas[i] = be16_to_cpu(buf[i]);
return 0;
}
static int scd4x_wait_meas_poll(struct scd4x_state *state)
{
struct i2c_client *client = state->client;
int tries = 6;
int ret;
do {
__be16 bval;
uint16_t val;
ret = scd4x_read(state, CMD_GET_DATA_READY, &bval, sizeof(bval));
if (ret)
return -EIO;
val = be16_to_cpu(bval);
/* new measurement available */
if (val & 0x7FF)
return 0;
msleep_interruptible(1000);
} while (--tries);
/* try to start sensor on timeout */
ret = scd4x_send_command(state, CMD_START_MEAS);
if (ret)
dev_err(&client->dev, "failed to start measurement: %d\n", ret);
return -ETIMEDOUT;
}
static int scd4x_read_poll(struct scd4x_state *state, uint16_t *buf)
{
int ret;
ret = scd4x_wait_meas_poll(state);
if (ret)
return ret;
return scd4x_read_meas(state, buf);
}
static int scd4x_read_channel(struct scd4x_state *state, int chan)
{
int ret;
uint16_t buf[3];
ret = scd4x_read_poll(state, buf);
if (ret)
return ret;
return buf[chan];
}
static int scd4x_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int *val,
int *val2, long mask)
{
struct scd4x_state *state = iio_priv(indio_dev);
int ret;
__be16 tmp;
switch (mask) {
case IIO_CHAN_INFO_RAW:
ret = iio_device_claim_direct_mode(indio_dev);
if (ret)
return ret;
mutex_lock(&state->lock);
ret = scd4x_read_channel(state, chan->address);
mutex_unlock(&state->lock);
iio_device_release_direct_mode(indio_dev);
if (ret < 0)
return ret;
*val = ret;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
if (chan->type == IIO_TEMP) {
*val = 175000;
*val2 = 65536;
return IIO_VAL_FRACTIONAL;
} else if (chan->type == IIO_HUMIDITYRELATIVE) {
*val = 100000;
*val2 = 65536;
return IIO_VAL_FRACTIONAL;
}
return -EINVAL;
case IIO_CHAN_INFO_OFFSET:
*val = -16852;
*val2 = 114286;
return IIO_VAL_INT_PLUS_MICRO;
case IIO_CHAN_INFO_CALIBBIAS:
mutex_lock(&state->lock);
ret = scd4x_read(state, CMD_GET_TEMP_OFFSET, &tmp, sizeof(tmp));
mutex_unlock(&state->lock);
if (ret)
return ret;
*val = be16_to_cpu(tmp);
return IIO_VAL_INT;
default:
return -EINVAL;
}
}
static int scd4x_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
int val, int val2, long mask)
{
struct scd4x_state *state = iio_priv(indio_dev);
int ret = 0;
switch (mask) {
case IIO_CHAN_INFO_CALIBBIAS:
mutex_lock(&state->lock);
ret = scd4x_write(state, CMD_SET_TEMP_OFFSET, val);
mutex_unlock(&state->lock);
return ret;
default:
return -EINVAL;
}
}
static ssize_t calibration_auto_enable_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct iio_dev *indio_dev = dev_to_iio_dev(dev);
struct scd4x_state *state = iio_priv(indio_dev);
int ret;
__be16 bval;
u16 val;
mutex_lock(&state->lock);
ret = scd4x_read(state, CMD_GET_ASC, &bval, sizeof(bval));
mutex_unlock(&state->lock);
if (ret) {
dev_err(dev, "failed to read automatic calibration");
return ret;
}
val = (be16_to_cpu(bval) & SCD4X_READY_MASK) ? 1 : 0;
return sprintf(buf, "%d\n", val);
}
static ssize_t calibration_auto_enable_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t len)
{
struct iio_dev *indio_dev = dev_to_iio_dev(dev);
struct scd4x_state *state = iio_priv(indio_dev);
bool val;
int ret;
uint16_t value;
ret = kstrtobool(buf, &val);
if (ret)
return ret;
value = val;
mutex_lock(&state->lock);
ret = scd4x_write(state, CMD_SET_ASC, value);
mutex_unlock(&state->lock);
if (ret)
dev_err(dev, "failed to set automatic calibration");
return ret ?: len;
}
static ssize_t calibration_forced_value_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t len)
{
struct iio_dev *indio_dev = dev_to_iio_dev(dev);
struct scd4x_state *state = iio_priv(indio_dev);
uint16_t val, arg;
int ret;
ret = kstrtou16(buf, 0, &arg);
if (ret)
return ret;
if (arg < SCD4X_FRC_MIN_PPM || arg > SCD4X_FRC_MAX_PPM)
return -EINVAL;
mutex_lock(&state->lock);
ret = scd4x_write_and_fetch(state, CMD_FRC, arg, &val, sizeof(val));
mutex_unlock(&state->lock);
if (val == 0xff) {
dev_err(dev, "forced calibration has failed");
return -EINVAL;
}
return ret ?: len;
}
static IIO_DEVICE_ATTR_RW(calibration_auto_enable, 0);
static IIO_DEVICE_ATTR_WO(calibration_forced_value, 0);
static IIO_CONST_ATTR(calibration_forced_value_available,
__stringify([SCD4X_FRC_MIN_PPM 1 SCD4X_FRC_MAX_PPM]));
static struct attribute *scd4x_attrs[] = {
&iio_dev_attr_calibration_auto_enable.dev_attr.attr,
&iio_dev_attr_calibration_forced_value.dev_attr.attr,
&iio_const_attr_calibration_forced_value_available.dev_attr.attr,
NULL
};
static const struct attribute_group scd4x_attr_group = {
.attrs = scd4x_attrs,
};
static const struct iio_info scd4x_info = {
.attrs = &scd4x_attr_group,
.read_raw = scd4x_read_raw,
.write_raw = scd4x_write_raw,
};
static const struct iio_chan_spec scd4x_channels[] = {
{
.type = IIO_CONCENTRATION,
.channel2 = IIO_MOD_CO2,
.modified = 1,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
.address = SCD4X_CO2,
.scan_index = SCD4X_CO2,
.scan_type = {
.sign = 'u',
.realbits = 16,
.storagebits = 16,
.endianness = IIO_BE,
},
},
{
.type = IIO_TEMP,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE) |
BIT(IIO_CHAN_INFO_OFFSET) |
BIT(IIO_CHAN_INFO_CALIBBIAS),
.address = SCD4X_TEMP,
.scan_index = SCD4X_TEMP,
.scan_type = {
.sign = 'u',
.realbits = 16,
.storagebits = 16,
.endianness = IIO_BE,
},
},
{
.type = IIO_HUMIDITYRELATIVE,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE),
.address = SCD4X_HR,
.scan_index = SCD4X_HR,
.scan_type = {
.sign = 'u',
.realbits = 16,
.storagebits = 16,
.endianness = IIO_BE,
},
},
};
static int __maybe_unused scd4x_suspend(struct device *dev)
{
struct iio_dev *indio_dev = dev_get_drvdata(dev);
struct scd4x_state *state = iio_priv(indio_dev);
int ret;
ret = scd4x_send_command(state, CMD_STOP_MEAS);
if (ret)
return ret;
return regulator_disable(state->vdd);
}
static int __maybe_unused scd4x_resume(struct device *dev)
{
struct iio_dev *indio_dev = dev_get_drvdata(dev);
struct scd4x_state *state = iio_priv(indio_dev);
int ret;
ret = regulator_enable(state->vdd);
if (ret)
return ret;
return scd4x_send_command(state, CMD_START_MEAS);
}
static __maybe_unused SIMPLE_DEV_PM_OPS(scd4x_pm_ops, scd4x_suspend, scd4x_resume);
static void scd4x_stop_meas(void *state)
{
scd4x_send_command(state, CMD_STOP_MEAS);
}
static void scd4x_disable_regulator(void *data)
{
struct scd4x_state *state = data;
regulator_disable(state->vdd);
}
static irqreturn_t scd4x_trigger_handler(int irq, void *p)
{
struct iio_poll_func *pf = p;
struct iio_dev *indio_dev = pf->indio_dev;
struct scd4x_state *state = iio_priv(indio_dev);
struct {
uint16_t data[3];
int64_t ts __aligned(8);
} scan;
int ret;
memset(&scan, 0, sizeof(scan));
mutex_lock(&state->lock);
ret = scd4x_read_poll(state, scan.data);
mutex_unlock(&state->lock);
if (ret)
goto out;
iio_push_to_buffers_with_timestamp(indio_dev, &scan, iio_get_time_ns(indio_dev));
out:
iio_trigger_notify_done(indio_dev->trig);
return IRQ_HANDLED;
}
static int scd4x_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
static const unsigned long scd4x_scan_masks[] = { 0x07, 0x00 };
struct device *dev = &client->dev;
struct iio_dev *indio_dev;
struct scd4x_state *state;
int ret;
indio_dev = devm_iio_device_alloc(dev, sizeof(*state));
if (!indio_dev)
return -ENOMEM;
state = iio_priv(indio_dev);
mutex_init(&state->lock);
state->client = client;
crc8_populate_msb(scd4x_crc8_table, SCD4X_CRC8_POLYNOMIAL);
indio_dev->info = &scd4x_info;
indio_dev->name = client->name;
indio_dev->channels = scd4x_channels;
indio_dev->num_channels = ARRAY_SIZE(scd4x_channels);
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->available_scan_masks = scd4x_scan_masks;
state->vdd = devm_regulator_get(dev, "vdd");
if (IS_ERR(state->vdd))
return dev_err_probe(dev, PTR_ERR(state->vdd), "failed to get regulator\n");
ret = regulator_enable(state->vdd);
if (ret)
return ret;
ret = devm_add_action_or_reset(dev, scd4x_disable_regulator, state);
if (ret)
return ret;
ret = scd4x_send_command(state, CMD_STOP_MEAS);
if (ret) {
dev_err(dev, "failed to stop measurement: %d\n", ret);
return ret;
}
/* execution time */
msleep_interruptible(500);
ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL, scd4x_trigger_handler, NULL);
if (ret)
return ret;
ret = scd4x_send_command(state, CMD_START_MEAS);
if (ret) {
dev_err(dev, "failed to start measurement: %d\n", ret);
return ret;
}
ret = devm_add_action_or_reset(dev, scd4x_stop_meas, state);
if (ret)
return ret;
return devm_iio_device_register(dev, indio_dev);
}
static const struct of_device_id scd4x_dt_ids[] = {
{ .compatible = "sensirion,scd40" },
{ .compatible = "sensirion,scd41" },
{ }
};
MODULE_DEVICE_TABLE(of, scd4x_dt_ids);
static struct i2c_driver scd4x_i2c_driver = {
.driver = {
.name = KBUILD_MODNAME,
.of_match_table = scd4x_dt_ids,
.pm = &scd4x_pm_ops
},
.probe = scd4x_probe,
};
module_i2c_driver(scd4x_i2c_driver);
MODULE_AUTHOR("Roan van Dijk <roan@protonic.nl>");
MODULE_DESCRIPTION("Sensirion SCD4X carbon dioxide sensor core driver");
MODULE_LICENSE("GPL v2");