[PATCH v4 0/2] iio: adc: ad7173: add ad4111 openwire detection support

[Guillaume Ranquet <granquet@baylibre.com>]

Hi.

This patch adds the openwire detection support for the ad4111 chip.

The openwire detection is done in software and relies on comparing the
results of two conversions on different channels.

The openwire detection on ad4111 is triggered automatically when a
single conversion is requested.
Due to the way openwire detection works on ad4111, implementing openwire
detection for continuous conversion mode is out of the scope of this
series.

Following discussion on V2, I have changed the event to be
IIO_EV_TYPE_FAULT and added a direction called IIO_EV_DIR_FAULT_OPENWIRE to
signal the specific fault.

The fault is level triggered (ie: the event will be sent as long as the
fault persists).
There's no event to signal that the fault has been "fixed", an absence
of FAULT event means that the open wire condition is not detected.

Thx,
Guillaume.

Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
---
Changes in v4:
- Rename IIO_EV_DIR_OPENWIRE to IIO_EV_DIR_FAULT_OPENWIRE to make it
  clearer the OPENWIRE direction is in the FAULT "namespace"
- Removal of the RFC prefix
- Link to v3: https://lore.kernel.org/r/20250116-ad4111_openwire-v3-0-ea9ebf29bd1d@baylibre.com

Changes in v3:
- Rename IIO_EV_TYPE_OPENWIRE to IIO_EV_TYPE_FAULT and add
  IIO_EV_DIR_OPENWIRE.
- Remove per channel open wire threshold configuration interface.
- Link to v2: https://lore.kernel.org/r/20250109-ad4111_openwire-v2-0-0372c2dde0ce@baylibre.com

Changes in v2:
- Introduce IIO_EV_TYPE_OPENWIRE instead of misusing the IIO_EV_THRESH
  event.
- Link to v1: https://lore.kernel.org/r/20241115-ad4111_openwire-v1-1-db97ac8bf250@baylibre.com

---
Guillaume Ranquet (2):
      iio: introduce the FAULT event type
      iio: adc: ad7173: add openwire detection support for single conversions

 drivers/iio/adc/ad7173.c         | 166 +++++++++++++++++++++++++++++++++++++++
 drivers/iio/industrialio-event.c |   2 +
 include/uapi/linux/iio/types.h   |   2 +
 tools/iio/iio_event_monitor.c    |   4 +
 4 files changed, 174 insertions(+)
---
base-commit: c849f534b9ea4688304f80f4571af75931dda7c1
change-id: 20241115-ad4111_openwire-e55deba8297f
prerequisite-message-id: <20241115-ad411x_calibration-v1-1-5f820dfb5c80@baylibre.com>
prerequisite-patch-id: 26241903b8fee8c4243e73d11fb2872cd9f52a15

Best regards,
-- 
Guillaume Ranquet <granquet@baylibre.com>