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,
