This series was born in order to provide more configuration options for max31856 devices. In this version, in order to do that, it also extends the IIO core. While at it, I've also updates maxim_thermocouple driver to take (little) advantage of the said change. Two hardware features (power mains noise rejection and HW averaging) were not previously configurable, and one (thermocouple type selection) was only possible via DT, but in my experience this is quite limiting in several scenario (see 3/3 commit message for complete explanation). These patches have been tested backporting max31856 driver on a 4.19 upstream kernel (Xilinx mpsoc-based board), and then rebased on the IIO testing git tree. I have real HW for max31856, while for maxim_thermocouple I've tested my changes as much as I could just spoofing in the DT (no real HW). Changes in v2: - 1/9 and 3/9: changed attribute name to better match IIO naming convention - 2/9: added separate patch to document new attribute name introduced in 1/9 - 4/9, 5/9, 6/9: new patches to add support to IIO core for handling thermocouple_type addribute. Most notably 4/9 introduces support for handling 'char' type IIO sysfs attributes; RFC on this. - 7/9: take advantage of just-added IIO thermocouple_type attribute instead of using extended custom attribute - 8/9 and 9/9: new patches to make maxim_thermocouple driver to export (RO) thermocouple_type attribute Andrea Merello (9): iio: max31856: add option for setting mains filter rejection frequency Documentation: ABI: document IIO in_temp_filter_notch_center_frequency file iio: max31856: add support for configuring the HW averaging RFC: iio: core: add char type for sysfs attributes iio: core: add thermocouple_type standard attribute Documentation: ABI: document IIO thermocouple_type file iio: max31856: add support for runtime-configuring the thermocouple type RFC/RFT: iio: maxim_thermocouple: add thermocouple_type sysfs attribute dt-bindings: iio: maxim_thermocouple: document new 'compatible' strings Documentation/ABI/testing/sysfs-bus-iio | 13 ++ .../iio/temperature/maxim_thermocouple.txt | 7 +- drivers/iio/industrialio-core.c | 23 ++- drivers/iio/temperature/max31856.c | 133 +++++++++++++++++- drivers/iio/temperature/maxim_thermocouple.c | 45 +++++- include/linux/iio/types.h | 2 + 6 files changed, 212 insertions(+), 11 deletions(-) Cc: Hartmut Knaack <knaack.h@xxxxxx> Cc: Lars-Peter Clausen <lars@xxxxxxxxxx> Cc: Peter Meerwald-Stadler <pmeerw@xxxxxxxxxx> Cc: Colin Ian King <colin.king@xxxxxxxxxxxxx> Cc: Patrick Havelange <patrick.havelange@xxxxxxxxxxxxx> Cc: Paresh Chaudhary <paresh.chaudhary@xxxxxxxxxxxxxxxxxxx> Cc: Matt Weber <matthew.weber@xxxxxxxxxxxxxxxxxxx> Cc: Matt Ranostay <matt.ranostay@xxxxxxxxxxxx> Cc: Chuhong Yuan <hslester96@xxxxxxxxx> Cc: Daniel Gomez <dagmcr@xxxxxxxxx> Cc: linux-iio@xxxxxxxxxxxxxxx -- 2.17.1