Add initial documentation for the ad4134 IIO driver.

Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
---
Change log v1 -> v2:
- Now using "~~~~~~~~" to mark fourth level topic.

 Documentation/iio/ad4134.rst | 58 ++++++++++++++++++++++++++++++++++++
 Documentation/iio/index.rst  |  1 +
 MAINTAINERS                  |  1 +
 3 files changed, 60 insertions(+)
 create mode 100644 Documentation/iio/ad4134.rst

diff --git a/Documentation/iio/ad4134.rst b/Documentation/iio/ad4134.rst
new file mode 100644
index 000000000000..fa44a05e6793
--- /dev/null
+++ b/Documentation/iio/ad4134.rst
@@ -0,0 +1,58 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+=============
+AD4134 driver
+=============
+
+Device driver for Analog Devices Inc. AD4134 and similar ADCs.
+
+Supported devices
+=================
+
+* `AD4134 <https://www.analog.com/AD4134>`_
+* `AD7134 <https://www.analog.com/AD7134>`_
+
+Wiring connections
+------------------
+
+AD4134 and similar ADCs can operate in a few different wiring configurations.
+
+Minimum I/O mode (SPI control mode)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The minimum I/O mode wiring allows AD4134 register and data access with the
+conventional set of SPI bus lines. The hardware configuration settings for using
+AD4134 in minimum I/O mode are:
+
++----------------------------+----------------------+--------------------+
+| Pin Function               |         Level        | Description        |
++============================+======================+====================+
+| PIN/SPI                    |         High         | SPI control mode   |
++----------------------------+----------------------+--------------------+
+| MODE                       |         Low          | ASRC slave mode    |
++----------------------------+----------------------+--------------------+
+| DCLKIO                     |         Low          | DCLK input         |
++----------------------------+----------------------+--------------------+
+| DCLKMODE                   |         Low          | Gated DCLK         |
++----------------------------+----------------------+--------------------+
+
+A possible connection schema that sets AD4134 digital interface for minimum I/O
+mode is:
+
+::
+
+                                 IOVDD
+      +------------------------+   |
+      |                PIN/SPI |<--+     +-------------+
+      |                        |         |     HOST    |
+      |                   DCLK |<--+     |             |
+      |           FORMAT1/SCLK |<--+---- | SCLK        |
+      |   AD4134      DEC2/SDI |<--------| SDO         |
+      |               DEC3/SDO |-------->| SDI         |
+      |                    ODR |<--------| GPIO        |
+      |             FORMAT0/CS |<--+     |             |
+      |                   MODE |<--+     +-------------+
+      |            DEC0/DCLKIO |<--+
+      |          DEC1/DCLKMODE |<--+
+      +------------------------+   |
+                                  GND
diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst
index 315ae37d6fd4..d4ed782c93a6 100644
--- a/Documentation/iio/index.rst
+++ b/Documentation/iio/index.rst
@@ -22,6 +22,7 @@ Industrial I/O Kernel Drivers
    ad3552r
    ad4000
    ad4030
+   ad4134
    ad4695
    ad7191
    ad7380
diff --git a/MAINTAINERS b/MAINTAINERS
index a1541cf3967b..b2c101598636 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1455,6 +1455,7 @@ L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad4134.yaml
+F:	Documentation/iio/ad4134.rst
 F:	drivers/iio/adc/ad4134.c
 
 ANALOG DEVICES INC AD4170-4 DRIVER
-- 
2.51.0