Certain ADC channels, such as the xilinx-ams temperature channels, give
milliCelcius already when read with iio_read_channel_processed.
Rather than having to provide a 1:1 dummy lookup table, simply allow to
bypass the mechanism.
Signed-off-by: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
First correct the edge case to return the last element if we're
outside the range, rather than at the last element, so that
interpolation is not omitted for points between the two last entries in
the table.
Then correct the formula to perform linear interpolation based the two
points surrounding the read ADC value. The indices for temp are kept as
"hi" and "lo" to pair with the adc indices, but there's no requirement
that the temperature is provided in descendent order. mult_frac() is
used to prevent issues with overflowing the int.
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
Everything mentionned here:
https://lkml.org/lkml/2016/4/20/850
This driver was added before the devm_iio_channel_get() function version was
merged. The sensor should be released before the iio channel, thus we had to
use the non-devm version of thermal_zone_of_sensor_register().
Now the devm_iio_channel_get() is available, do the corresponding change in
this driver and remove gadc_thermal_remove().
[Compiled tested only]
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
In some of platform, thermal sensors like NCT thermistors are
connected to the one of ADC channel. The temperature is read by
reading the voltage across the sensor resistance via ADC. Lookup
table for ADC read value to temperature is referred to get
temperature. ADC is read via IIO framework.
Add support for thermal sensor driver which read the voltage across
sensor resistance from ADC through IIO framework.
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>