iio: humidity: hdc3020: add threshold events support

Add threshold events support for temperature and relative humidity. To
enable them the higher and lower threshold registers must be programmed
and the higher threshold must be greater then or equal to the lower
threshold. Otherwise the event is disabled. Invalid hysteresis values
are ignored by the device. There is no further configuration possible.

Tested by setting thresholds/hysteresis and turning the heater on/off.
Used iio_event_monitor in tools/iio to catch events while constantly
displaying temperature and humidity values.

Signed-off-by: Dimitri Fedrau <dima.fedrau@gmail.com>
Tested-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://lore.kernel.org/r/20240214085350.19382-4-dima.fedrau@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: humidity: hdc3020: switch to 16bit register defines

Switch to 16bit register defines and drop the const u8 register pairs.
By doing so we change the parameter of functions for reading and writing
to the device. Additionally create helper functions that are aware of the
new register format and apply them wherever possible.

Signed-off-by: Dimitri Fedrau <dima.fedrau@gmail.com>
Link: https://lore.kernel.org/r/20240214085350.19382-2-dima.fedrau@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: humidity: hdc3020: fix temperature offset

The temperature offset should be negative according to the datasheet.
Adding a minus to the existing offset results in correct temperature
calculations.

Fixes: c9180b8e39be ("iio: humidity: Add driver for ti HDC302x humidity sensors")
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Signed-off-by: Dimitri Fedrau <dima.fedrau@gmail.com>
Link: https://lore.kernel.org/r/20240126135226.3977904-1-dima.fedrau@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

iio: humidity: Add driver for ti HDC302x humidity sensors

Add support for HDC302x integrated capacitive based relative
humidity (RH) and temperature sensor.
This driver supports reading values, reading the maximum and
minimum of values and controlling the integrated heater of
the sensor.

Co-developed-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Signed-off-by: Li peiyu <579lpy@gmail.com>
Link: https://lore.kernel.org/r/20231211122940.9791-1-579lpy@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>