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iio: chemical: scd4x: Add pressure compensation

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This patch adds pressure compensation to the scd4x driver. The pressure can
be written to the sensor in hPa. The pressure will be compensated
internally by the sensor.

Signed-off-by: Roan van Dijk <roan@protonic.nl>
Link: https://lore.kernel.org/r/20230711101419.2065107-1-roan@protonic.nl
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Roan van Dijk 2023-07-11 12:14:19 +02:00 committed by Jonathan Cameron
parent 4dc8f99dab
commit 3f3caf5b2e
1 changed files with 73 additions and 6 deletions
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79
drivers/iio/chemical/scd4x.c
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@ -36,6 +36,8 @@
#define SCD4X_WRITE_BUF_SIZE 5
#define SCD4X_FRC_MIN_PPM 0
#define SCD4X_FRC_MAX_PPM 2000
#define SCD4X_PRESSURE_COMP_MIN_MBAR 700
#define SCD4X_PRESSURE_COMP_MAX_MBAR 1200
#define SCD4X_READY_MASK 0x01
/*Commands SCD4X*/
@ -45,6 +47,8 @@ enum scd4x_cmd {
CMD_STOP_MEAS = 0x3f86,
CMD_SET_TEMP_OFFSET = 0x241d,
CMD_GET_TEMP_OFFSET = 0x2318,
CMD_SET_AMB_PRESSURE = 0xe000,
CMD_GET_AMB_PRESSURE = 0xe000,
CMD_FRC = 0x362f,
CMD_SET_ASC = 0x2416,
CMD_GET_ASC = 0x2313,
@ -137,7 +141,8 @@ static int scd4x_read(struct scd4x_state *state, enum scd4x_cmd cmd,
* 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)) {
if ((cmd != CMD_GET_DATA_READY) && (cmd != CMD_READ_MEAS) &&
(cmd != CMD_GET_AMB_PRESSURE)) {
ret = scd4x_send_command(state, CMD_STOP_MEAS);
if (ret)
return ret;
@ -166,7 +171,8 @@ static int scd4x_read(struct scd4x_state *state, enum scd4x_cmd cmd,
}
/* start measurement */
if ((cmd != CMD_GET_DATA_READY) && (cmd != CMD_READ_MEAS)) {
if ((cmd != CMD_GET_DATA_READY) && (cmd != CMD_READ_MEAS) &&
(cmd != CMD_GET_AMB_PRESSURE)) {
ret = scd4x_send_command(state, CMD_START_MEAS);
if (ret)
return ret;
@ -188,9 +194,11 @@ static int scd4x_write(struct scd4x_state *state, enum scd4x_cmd cmd, uint16_t a
buf[4] = crc;
/* measurement needs to be stopped before sending commands */
ret = scd4x_send_command(state, CMD_STOP_MEAS);
if (ret)
return ret;
if (cmd != CMD_SET_AMB_PRESSURE) {
ret = scd4x_send_command(state, CMD_STOP_MEAS);
if (ret)
return ret;
}
/* execution time */
msleep_interruptible(500);
@ -200,7 +208,7 @@ static int scd4x_write(struct scd4x_state *state, enum scd4x_cmd cmd, uint16_t a
return ret;
/* start measurement, except for forced calibration command */
if (cmd != CMD_FRC) {
if ((cmd != CMD_FRC) && (cmd != CMD_SET_AMB_PRESSURE)) {
ret = scd4x_send_command(state, CMD_START_MEAS);
if (ret)
return ret;
@ -338,6 +346,18 @@ static int scd4x_read_raw(struct iio_dev *indio_dev,
switch (mask) {
case IIO_CHAN_INFO_RAW:
if (chan->output) {
mutex_lock(&state->lock);
ret = scd4x_read(state, CMD_GET_AMB_PRESSURE, &tmp, sizeof(tmp));
mutex_unlock(&state->lock);
if (ret)
return ret;
*val = be16_to_cpu(tmp);
return IIO_VAL_INT;
}
ret = iio_device_claim_direct_mode(indio_dev);
if (ret)
return ret;
@ -386,6 +406,25 @@ static int scd4x_read_raw(struct iio_dev *indio_dev,
}
}
static const int scd4x_pressure_calibbias_available[] = {
SCD4X_PRESSURE_COMP_MIN_MBAR, 1, SCD4X_PRESSURE_COMP_MAX_MBAR,
};
static int scd4x_read_avail(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
const int **vals, int *type, int *length, long mask)
{
switch (mask) {
case IIO_CHAN_INFO_RAW:
*vals = scd4x_pressure_calibbias_available;
*type = IIO_VAL_INT;
return IIO_AVAIL_RANGE;
}
return -EINVAL;
}
static int scd4x_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
int val, int val2, long mask)
{
@ -399,6 +438,21 @@ static int scd4x_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const
mutex_unlock(&state->lock);
return ret;
case IIO_CHAN_INFO_RAW:
switch (chan->type) {
case IIO_PRESSURE:
if (val < SCD4X_PRESSURE_COMP_MIN_MBAR ||
val > SCD4X_PRESSURE_COMP_MAX_MBAR)
return -EINVAL;
mutex_lock(&state->lock);
ret = scd4x_write(state, CMD_SET_AMB_PRESSURE, val);
mutex_unlock(&state->lock);
return ret;
default:
return -EINVAL;
}
default:
return -EINVAL;
}
@ -503,9 +557,22 @@ static const struct iio_info scd4x_info = {
.attrs = &scd4x_attr_group,
.read_raw = scd4x_read_raw,
.write_raw = scd4x_write_raw,
.read_avail = scd4x_read_avail,
};
static const struct iio_chan_spec scd4x_channels[] = {
{
/*
* this channel is special in a sense we are pretending that
* sensor is able to change measurement chamber pressure but in
* fact we're just setting pressure compensation value
*/
.type = IIO_PRESSURE,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
.info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW),
.output = 1,
.scan_index = -1,
},
{
.type = IIO_CONCENTRATION,
.channel2 = IIO_MOD_CO2,