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@xxxxxxxxxxx> --- drivers/iio/chemical/Kconfig | 13 + drivers/iio/chemical/Makefile | 1 + drivers/iio/chemical/scd4x.c | 690 ++++++++++++++++++++++++++++++++++ 3 files changed, 704 insertions(+) create mode 100644 drivers/iio/chemical/scd4x.c diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig index c03667e62732..f4d2fcb1b9ac 100644 --- a/drivers/iio/chemical/Kconfig +++ b/drivers/iio/chemical/Kconfig @@ -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 cabon + 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 diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile index d07af581f234..81b29d9eb6a2 100644 --- a/drivers/iio/chemical/Makefile +++ b/drivers/iio/chemical/Makefile @@ -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_SENSIRION_SGP30) += sgp30.o obj-$(CONFIG_SENSIRION_SGP40) += sgp40.o obj-$(CONFIG_SPS30) += sps30.o diff --git a/drivers/iio/chemical/scd4x.c b/drivers/iio/chemical/scd4x.c new file mode 100644 index 000000000000..4eaf50442f6e --- /dev/null +++ b/drivers/iio/chemical/scd4x.c @@ -0,0 +1,690 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Sensirion SCD4X carbon dioxide sensor i2c driver + * + * Copyright (C) 2021 Protonic Holland + * Author: Roan van Dijk <roan@xxxxxxxxxxx> + * + * 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; + uint16_t 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 { + uint16_t val; + + ret = scd4x_read(state, CMD_GET_DATA_READY, &val, sizeof(val)); + if (ret) + return -EIO; + val = be16_to_cpu(val); + + /* 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; + uint16_t 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; + uint16_t val; + + mutex_lock(&state->lock); + ret = scd4x_read(state, CMD_GET_ASC, &val, sizeof(val)); + mutex_unlock(&state->lock); + if (ret) { + dev_err(dev, "failed to read automatic calibration"); + return ret; + } + + val = (be16_to_cpu(val) & 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; + uint16_t buf[3]; + + memset(&scan, 0, sizeof(scan)); + mutex_lock(&state->lock); + ret = scd4x_read_poll(state, buf); + 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@xxxxxxxxxxx>"); +MODULE_DESCRIPTION("Sensirion SCD4X carbon dioxide sensor core driver"); +MODULE_LICENSE("GPL v2"); -- 2.30.2
