[v1,4/4] Documentation: iio: ad4000: Describe offload support

Commit Message

Marcelo Schmitt March 14, 2025, 5:19 p.m. UTC

When SPI offloading is supported, the IIO device provides different sysfs
interfaces to allow using the adjusting the sample rate. Document SPI
offload support for AD4000 and similar devices.

Signed-off-by: Marcelo Schmitt <[e-mail]>
---
 Documentation/iio/ad4000.rst | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

Patch

diff --git a/Documentation/iio/ad4000.rst b/Documentation/iio/ad4000.rst
index 468d30dc9214..2d56b0762570 100644
--- a/Documentation/iio/ad4000.rst
+++ b/Documentation/iio/ad4000.rst
@@ -191,3 +191,20 @@  Typical voltage channel attributes of a differential AD4000 series device:
 +-------------------------------------------+------------------------------------------+
 | ``in_voltage0-voltage1_scale_available``  | Toggles input span compression           |
 +-------------------------------------------+------------------------------------------+
+
+SPI offload support
+-------------------
+
+To be able to achieve the maximum sample rate, the driver can be used with the
+`AXI SPI Engine`_ to provide SPI offload support.
+
+.. _AXI SPI Engine: http://analogdevicesinc.github.io/hdl/projects/pulsar_adc/index.html
+
+When set for SPI offload support, the IIO device will provide different
+interfaces.
+
+* Either ``in_voltage0_sampling_frequency`` or
+  ``in_voltage0-voltage1_sampling_frequency`` file is provided to allow setting
+  the sample rate.
+* IIO trigger device is not provided (no ``trigger`` directory).
+* ``timestamp`` channel is not provided.