docs: iio: ad7380: add alert support

Add a section for alert support, explaining how user can use iio events
attributes to enable alert and set thresholds.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Julien Stephan <jstephan@baylibre.com>
Link: https://patch.msgid.link/20250108-ad7380-add-alert-support-v4-5-1751802471ba@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/Documentation/iio/ad7380.rst b/Documentation/iio/ad7380.rst
index c46127700e14ca9ec3cac0bd5776b6702f2659e2..cff688bcc2d9601a9faf42d5e9c217486639ca66 100644 (file)
--- a/Documentation/iio/ad7380.rst
+++ b/Documentation/iio/ad7380.rst
@@ -92,6 +92,38 @@ must restart iiod using the following command:
 
        root:~# systemctl restart iiod
 
+Alert
+-----
+
+2 channels variants of the ad738x family, can use the SDOB line as an alert pin
+when configured in 1 SDO line mode. 4 channels variants, can use SDOD as an
+alert pin when configured in 1 or 2 SDO line(s) mode, although only 1 SDO line
+mode is currently supported by the driver (see `SPI wiring modes`_).
+
+At the end of a conversion the active-low alert pin gets asserted if the
+conversion result exceeds the alert high limit or falls below the alert low
+limit. It is cleared, on a falling edge of CS. The alert pin is common to all
+channels.
+
+User can enable alert using the regular iio events attribute:
+
+.. code-block:: bash
+
+       events/thresh_either_en
+
+The high and low thresholds are common to all channels and can also be set using
+regular iio events attributes:
+
+.. code-block:: bash
+
+       events/in_thresh_falling_value
+       events/in_thresh_rising_value
+
+If debugfs is available, user can read the ALERT register to determine the
+faulty channel and direction.
+
+In most use cases, user will hardwire the alert pin to trigger a shutdown.
+
 Channel selection and sequencer (single-end chips only)
 -------------------------------------------------------
 
@@ -144,7 +176,6 @@ Unimplemented features
 - Rolling average oversampling
 - Power down mode
 - CRC indication
-- Alert
 
 
 Device buffers