Complement ad4000 IIO driver documentation with considerations about
``_scale_available`` attribute and table of typical channel attributes.
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@xxxxxxxxxx>
---
Documentation/iio/ad4000.rst | 47 ++++++++++++++++++++++++++++++++++++
1 file changed, 47 insertions(+)
diff --git a/Documentation/iio/ad4000.rst b/Documentation/iio/ad4000.rst
index 5578a9cfd9d5..468d30dc9214 100644
--- a/Documentation/iio/ad4000.rst
+++ b/Documentation/iio/ad4000.rst
@@ -144,3 +144,50 @@ Set ``adi,sdi-pin`` to ``"cs"`` to select this mode.
^ | |
+--------------------| SCLK |
+-------------+
+
+IIO Device characteristics
+==========================
+
+The AD4000 series driver supports differential and pseudo-differential ADCs.
+
+The span compression feature available in AD4000 series devices can be
+enabled/disabled by changing the ``_scale_available`` attribute of the voltage
+channel. Note that span compression configuration requires writing to AD4000
+configuration register, which is only possible when the ADC is wired in 3-wire
+turbo mode, and the SPI controller is ``SPI_MOSI_IDLE_HIGH`` capable. If those
+conditions are not met, no ``_scale_available`` attribute is provided.
+
+Besides that, differential and pseudo-differential voltage channels present
+slightly different sysfs interfaces.
+
+Pseudo-differential ADCs
+------------------------
+
+Typical voltage channel attributes of a pseudo-differential AD4000 series device:
+
++-------------------------------------------+------------------------------------------+
+| Voltage Channel Attributes | Description |
++===========================================+==========================================+
+| ``in_voltage0_raw`` | Raw ADC output code. |
++-------------------------------------------+------------------------------------------+
+| ``in_voltage0_offset`` | Offset to convert raw value to mV. |
++-------------------------------------------+------------------------------------------+
+| ``in_voltage0_scale`` | Scale factor to convert raw value to mV. |
++-------------------------------------------+------------------------------------------+
+| ``in_voltage0_scale_available`` | Toggles input span compression |
++-------------------------------------------+------------------------------------------+
+
+Differential ADCs
+-----------------
+
+Typical voltage channel attributes of a differential AD4000 series device:
+
++-------------------------------------------+------------------------------------------+
+| Voltage Channel Attributes | Description |
++===========================================+==========================================+
+| ``in_voltage0-voltage1_raw`` | Raw ADC output code. |
++-------------------------------------------+------------------------------------------+
+| ``in_voltage0-voltage1_scale`` | Scale factor to convert raw value to mV. |
++-------------------------------------------+------------------------------------------+
+| ``in_voltage0-voltage1_scale_available`` | Toggles input span compression |
++-------------------------------------------+------------------------------------------+
--
2.47.2
