On Thu, 6 Jul 2023 14:27:26 +0200
Roan van Dijk <roan@xxxxxxxxxxx> wrote:
> It seems I missed that one, didn't know it you can't have a channel with
> only calibias.
> In the next version of this patch I will change it to an output channel
> like the other cases.
> I saw the scd30 did this as well.
It's not so much that you can't have such a channel, more that we seem
to have sort of standardized on using a straight forward output for this.
Doesn't change the suggestion for this patch, but there 'might' be a usecase
for such a channel in the future..
Jonathan
>
> Roan
>
> On 06-07-2023 03:28, Jonathan Cameron wrote:
> > On Tue, 4 Jul 2023 10:47:06 +0200
> > Roan van Dijk<roan@xxxxxxxxxxx> wrote:
> >
> >> 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>
> > Why treat this as a channel with just calibbias?
> > From what I can recall we've previous treated such cases as an
> > output channel with the advantage that the units are then fully
> > defined. I may well be forgetting some argument or a case that
> > does it with calibbias though.
> >
> > Jonathan
> >
> >
> >> ---
> >> drivers/iio/chemical/scd4x.c | 41 +++++++++++++++++++++++++++++++++---
> >> 1 file changed, 38 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/iio/chemical/scd4x.c b/drivers/iio/chemical/scd4x.c
> >> index a4f22d926400..fe6b3f3f7186 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_AMB_PRESSURE_MIN 700
> >> +#define SCD4X_AMB_PRESSURE_MAX 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,
> >> @@ -373,7 +377,10 @@ static int scd4x_read_raw(struct iio_dev *indio_dev,
> >> 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));
> >> + if (chan->type == IIO_TEMP)
> >> + ret = scd4x_read(state, CMD_GET_TEMP_OFFSET, &tmp, sizeof(tmp));
> >> + else if (chan->type == IIO_PRESSURE)
> >> + ret = scd4x_read(state, CMD_GET_AMB_PRESSURE, &tmp, sizeof(tmp));
> >> mutex_unlock(&state->lock);
> >> if (ret)
> >> return ret;
> >> @@ -386,6 +393,25 @@ static int scd4x_read_raw(struct iio_dev *indio_dev,
> >> }
> >> }
> >>
> >> +static const int scd4x_pressure_calibbias_available[] = {
> >> + SCD4X_AMB_PRESSURE_MIN, 1, SCD4X_AMB_PRESSURE_MAX,
> >> +};
> >> +
> >> +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_CALIBBIAS:
> >> + *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)
> >> {
> >> @@ -395,9 +421,11 @@ static int scd4x_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const
> >> switch (mask) {
> >> case IIO_CHAN_INFO_CALIBBIAS:
> >> mutex_lock(&state->lock);
> >> - ret = scd4x_write(state, CMD_SET_TEMP_OFFSET, val);
> >> + if (chan->type == IIO_TEMP)
> >> + ret = scd4x_write(state, CMD_SET_TEMP_OFFSET, val);
> >> + else if (chan->type == IIO_PRESSURE)
> >> + ret = scd4x_write(state, CMD_SET_AMB_PRESSURE, val);
> >> mutex_unlock(&state->lock);
> >> -
> >> return ret;
> >> default:
> >> return -EINVAL;
> >> @@ -503,9 +531,16 @@ 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[] = {
> >> + {
> >> + .type = IIO_PRESSURE,
> >> + .info_mask_separate = BIT(IIO_CHAN_INFO_CALIBBIAS),
> >> + .info_mask_separate_available = BIT(IIO_CHAN_INFO_CALIBBIAS),
> >> + .scan_index = -1,
> >> + },
> >> {
> >> .type = IIO_CONCENTRATION,
> >> .channel2 = IIO_MOD_CO2,
