iio: tmag5273: fix temperature offset

The current offset has the scale already applied to it. The ABI
documentation defines the offset parameter as "offset to be added
to <type>[Y]_raw prior to scaling by <type>[Y]_scale in order to
obtain value in the <type> units as specified in <type>[Y]_raw
documentation"

The right value is obtained at 0 degrees Celsius by the formula provided
in the datasheet:

T = Tsens_t0 + (Tadc_t - Tadc_t0) / Tadc_res

where:
T = 0 degrees Celsius
Tsens_t0 (reference temperature) = 25 degrees Celsius
Tadc_t0 (16-bit format for Tsens_t0) = 17508
Tadc_res = 60.1 LSB/degree Celsius

The resulting offset is 16005.5, which has been truncated to 16005 to
provide an integer value with a precision loss smaller than the 1-LSB
measurement precision.

Fix the offset to apply its value prior to scaling.

Signed-off-by: Javier Carrasco <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Cc: <[email protected]>
Signed-off-by: Jonathan Cameron <[email protected]>

0 files changed, 0 insertions, 0 deletions