Export this function in preparation for the fix in veml6030.c, where the
total gain can be used to ease the calculation of the processed value of
the IIO_LIGHT channel compared to acquiring the scale in NANO.
Suggested-by: Matti Vaittinen <mazziesaccount@gmail.com>
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Reviewed-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://patch.msgid.link/20250127-veml6030-scale-v3-1-4f32ba03df94@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This helper functions reduce the burden in the drivers that want to
fetch a gain and time selector for a given scale or a new optimal gain.
The former is currently achieved by calling
iio_gts_find_gain_sel_for_scale_using_time() for the current time
selector, and then iterating over the rest of time selectors if the
gain selector was not found.
The latter requires a combination of multiple iio-gts helpers to find
the new gain, look for an optimal gain if there was no exact match, and
set a minimum gain if the optimal gain is not in the range of available
gains.
Provide simpler workflows by means of functions that address common
patterns in the users of the iio-gts helpers.
Acked-by: Matti Vaittinen <mazziesaccount@gmail.com>
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://patch.msgid.link/20241230-veml3235_scale-v3-1-48a5795e2f64@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
The kerneldoc for iio_gts_find_sel_by_int_time() has an error.
Documentation states that function is searching a selector for a HW-gain
while it is searching a selector for an integration time.
Fix the documentation by saying the function is looking for a selector
for an integration time.
Fixes: 38416c28e1 ("iio: light: Add gain-time-scale helpers")
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/ZEIjI4YUzqPZk/9X@fedora
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Some light sensors can adjust both the HW-gain and integration time.
There are cases where adjusting the integration time has similar impact
to the scale of the reported values as gain setting has.
IIO users do typically expect to handle scale by a single writable 'scale'
entry. Driver should then adjust the gain/time accordingly.
It however is difficult for a driver to know whether it should change
gain or integration time to meet the requested scale. Usually it is
preferred to have longer integration time which usually improves
accuracy, but there may be use-cases where long measurement times can be
an issue. Thus it can be preferable to allow also changing the
integration time - but mitigate the scale impact by also changing the gain
underneath. Eg, if integration time change doubles the measured values,
the driver can reduce the HW-gain to half.
The theory of the computations of gain-time-scale is simple. However,
some people (undersigned) got that implemented wrong for more than once.
Add some gain-time-scale helpers in order to not dublicate errors in all
drivers needing these computations.
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/268d418e7cffcdaa2ece6738478bbc57692c213e.1680263956.git.mazziesaccount@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
