One comment inline.
On 20 August 2015 at 16:11, Nicola Corna <nicola@xxxxxxxxxx> wrote:
>
> The value given by the
> Si7013/20/21 modules needs a conversion using a
> small expression in order to obtain the measurement in °C or %RH. This
> patch adds the computation inside the si7020 module, allowing the user to
> obtain the measurement in m°C and 10E-3%RH without any additional
> calculation.
>
> Signed-off-by: Nicola Corna <nicola@xxxxxxxxxx>
Acked-by: Crt Mori <cmo@xxxxxxxxxxx>
>
> ---
> drivers/iio/humidity/si7020.c | 18 ++++++++++++++++--
> 1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/humidity/si7020.c b/drivers/iio/humidity/si7020.c
> index a8bad04..c534706 100644
> --- a/drivers/iio/humidity/si7020.c
> +++ b/drivers/iio/humidity/si7020.c
> @@ -70,6 +70,7 @@ static int si7020_read_raw(struct iio_dev *indio_dev,
>
> switch (mask) {
> case IIO_CHAN_INFO_RAW:
> + case IIO_CHAN_INFO_PROCESSED:
> if (holdmode) {
> ret = i2c_smbus_read_word_data(*client,
> chan->type == IIO_TEMP ?
> @@ -108,6 +109,17 @@ static int si7020_read_raw(struct iio_dev *indio_dev,
> else if (*val > 55575) /* 100%RH */
> *val = 55575;
> }
> + if (mask == IIO_CHAN_INFO_PROCESSED) {
> + /*
> + * To avoid overflows the fractions can be simplified:
> + * temperature --> 175720 / (65536 >> 2) = 21965 / 2048
> + * humidity --> 125000 / (65536 >> 2) = 15625 / 2048
> + */
> + if (chan->type == IIO_TEMP)
> + *val = (*val - 4368) * 21965 / 2048;
I was suggested by Peter Meerwald to use parenthesis in case like this
(and below).
>
> + else
> + *val = (*val - 768) * 15625 / 2048;
> + }
> return IIO_VAL_INT;
> case IIO_CHAN_INFO_SCALE:
> if (chan->type == IIO_TEMP)
> @@ -142,12 +154,14 @@ static const struct iio_chan_spec si7020_channels[] = {
> {
> .type = IIO_HUMIDITYRELATIVE,
> .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> - BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
> + BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET) |
> + BIT(IIO_CHAN_INFO_PROCESSED),
> },
> {
> .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_SCALE) | BIT(IIO_CHAN_INFO_OFFSET) |
> + BIT(IIO_CHAN_INFO_PROCESSED),
> }
> };
>
> --
> 2.5.0
>
> --
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