[PATCH RFC 3/3] docs: iio: new docs for ad7625 driver

[Trevor Gamblin <tgamblin@baylibre.com>]

Add documentation for the AD7625/AD7626/AD7960/AD7961 ADCs.

Signed-off-by: Trevor Gamblin <tgamblin@baylibre.com>
---
 Documentation/iio/ad7625.rst | 91 ++++++++++++++++++++++++++++++++++++++++++++
 MAINTAINERS                  |  1 +
 2 files changed, 92 insertions(+)

diff --git a/Documentation/iio/ad7625.rst b/Documentation/iio/ad7625.rst
new file mode 100644
index 000000000000..61761e3b75c3
--- /dev/null
+++ b/Documentation/iio/ad7625.rst
@@ -0,0 +1,91 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+====================
+AD7625 driver
+====================
+
+ADC driver for Analog Devices Inc. AD7625, AD7626, AD7960, and AD7961
+devices. The module name is ``ad7625``.
+
+Supported devices
+=================
+
+The following chips are supported by this driver:
+
+* `AD7625 <https://www.analog.com/AD7625>`_
+* `AD7626 <https://www.analog.com/AD7626>`_
+* `AD7960 <https://www.analog.com/AD7960>`_
+* `AD7961 <https://www.analog.com/AD7961>`_
+
+The driver requires use of the Pulsar LVDS HDL project:
+
+* `Pulsar LVDS HDL <http://analogdevicesinc.github.io/hdl/projects/pulsar_lvds/index.html>`_
+
+To trigger conversions and enable subsequent data transfer, the devices
+require coupled PWM signals with a phase offset.
+
+Supported features
+==================
+
+Conversion control modes
+------------------------
+
+The driver currently supports one of two possible LVDS conversion control methods.
+
+Echoed-Clock interface mode
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code-block::
+
+                                                +----------------+
+                     +xxxxxxxxxxxxxxxxxxxxxxxxxx| CNV            |
+                     X                          |                |
+                     v                          |    HOST        |
+          +----------------------------+        |                |
+          |      CNV+/CNV-   DCO+/DCO- |xxxxxxx>| CLK_IN         |
+          |                            |        |                |
+          |                            |        |                |
+          |       AD7625         D+/D- |xxxxxxx>| DATA_IN        |
+          |                            |        |                |
+          |                            |        |                |
+          |                  CLK+/CLK- |<xxxxxxx| CLK & CLK_GATE |
+          +----------------------------+        |                |
+                                                +----------------+
+
+Reference voltage
+-----------------
+
+Three possible reference voltage sources are supported:
+
+- Internal reference (only available on AD7625 and AD7626)
+- External reference and internal buffer
+- External reference
+
+The source is determined by the device tree. If ``ref-supply`` is present, then
+the external reference is used. If ``refin-supply`` is present, then the internal
+buffer is used. If neither is present, then the internal reference is used.
+
+Unimplemented features
+----------------------
+
+- Self-clocked mode
+
+
+Device attributes
+=================
+
+The AD762x is a fully-differential ADC and has the following attributes:
+
++---------------------------------------+--------------------------------------------------------------+
+| Attribute                             | Description                                                  |
++=======================================+==============================================================+
+| ``scale``                             | Scale factor to convert raw value from buffered reads to mV. |
++---------------------------------------+--------------------------------------------------------------+
+
+
+Device buffers
+==============
+
+This driver supports IIO triggered buffers.
+
+See :doc:`iio_devbuf` for more information.
diff --git a/MAINTAINERS b/MAINTAINERS
index a90972e1c5c5..97c9b03e1cf0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1268,6 +1268,7 @@ S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 W:	http://analogdevicesinc.github.io/hdl/projects/pulsar_lvds/index.html
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad7625.yaml
+F:	Documentation/iio/ad7625.rst
 F:	drivers/iio/adc/ad7625.c
 
 ANALOG DEVICES INC AD7768-1 DRIVER

-- 
2.39.2