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@xxxxxxxxxxx>
---
Changes since v2:
- Fix for kernel test robot errors of uninitialized symbols
- Changed pressure compensation to output channel instead of a channel
with calibbias
- Pressure can now be compensated during measurements
drivers/iio/chemical/scd4x.c | 79 +++++++++++++++++++++++++++++++++---
1 file changed, 73 insertions(+), 6 deletions(-)
diff --git a/drivers/iio/chemical/scd4x.c b/drivers/iio/chemical/scd4x.c
index a4f22d926400..4bb5d215c54c 100644
--- a/drivers/iio/chemical/scd4x.c
+++ b/drivers/iio/chemical/scd4x.c
@@ -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,
--
2.39.2
