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>
---
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;
+ 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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