[PATCH v2 0/2] docs: iio: new docs for ad7944 driver

[PATCH v2 0/2] docs: iio: new docs for ad7944 driver

[David Lechner]

Adding documentation for the recently applied ad7944 driver.

Note: this also covers the features added in [1] that hasn't been
applied yet.

[1]: https://lore.kernel.org/linux-iio/20240311-mainline-ad7944-3-wire-mode-v1-1-8e8199efa1f7@baylibre.com/

Also updating the MAINTAINERS file to catch iio documentation since this
seems to have been overlooked.

---
Changes in v2:
- Removed some paragraphs that would be redundant for most drivers,
  e.g. most of the buffer section.
- Link to v1: https://lore.kernel.org/r/20240313-mainline-ad7944-doc-v1-0-7860416726e4@baylibre.com

---
David Lechner (2):
      MAINTAINERS: add Documentation/iio/ to IIO subsystem
      docs: iio: new docs for ad7944 driver

 Documentation/iio/ad7944.rst | 130 +++++++++++++++++++++++++++++++++++++++++++
 Documentation/iio/index.rst  |   1 +
 MAINTAINERS                  |   2 +
 3 files changed, 133 insertions(+)
---
base-commit: bbafdb305d6b00934cc09a90ec1bb659d43e5171
change-id: 20240313-mainline-ad7944-doc-285b47ed6d35

[PATCH v2 1/2] MAINTAINERS: add Documentation/iio/ to IIO subsystem

[David Lechner]

Patches touching the IIO subsystem documentation should also be sent to
the IIO mailing list.

Signed-off-by: David Lechner <dlechner@baylibre.com>
---
 MAINTAINERS | 1 +
 1 file changed, 1 insertion(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 7b1a6f2d0c9c..fb2377bad376 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10466,6 +10466,7 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio.git
 F:	Documentation/ABI/testing/configfs-iio*
 F:	Documentation/ABI/testing/sysfs-bus-iio*
 F:	Documentation/devicetree/bindings/iio/
+F:	Documentation/iio/
 F:	drivers/iio/
 F:	drivers/staging/iio/
 F:	include/dt-bindings/iio/

-- 
2.43.2

[PATCH v2 2/2] docs: iio: new docs for ad7944 driver

[David Lechner]

This adds a new page to document how to use the ad7944 ADC driver.

Signed-off-by: David Lechner <dlechner@baylibre.com>
---
 Documentation/iio/ad7944.rst | 130 +++++++++++++++++++++++++++++++++++++++++++
 Documentation/iio/index.rst  |   1 +
 MAINTAINERS                  |   1 +
 3 files changed, 132 insertions(+)

diff --git a/Documentation/iio/ad7944.rst b/Documentation/iio/ad7944.rst
new file mode 100644
index 000000000000..f418ab1288ae
--- /dev/null
+++ b/Documentation/iio/ad7944.rst
@@ -0,0 +1,130 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+=============
+AD7944 driver
+=============
+
+ADC driver for Analog Devices Inc. AD7944 and similar devices. The module name
+is ``ad7944``.
+
+
+Supported devices
+=================
+
+The following chips are supported by this driver:
+
+* `AD7944 <https://www.analog.com/AD7944>`_
+* `AD7985 <https://www.analog.com/AD7985>`_
+* `AD7986 <https://www.analog.com/AD7986>`_
+
+
+Supported features
+==================
+
+SPI wiring modes
+----------------
+
+The driver currently supports two of the many possible SPI wiring configurations.
+
+CS mode, 3-wire, without busy indicator
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code-block::
+
+                                         +-------------+
+                    +--------------------| CS          |
+                    v                    |             |
+    VIO   +--------------------+         |     HOST    |
+     |    |        CNV         |         |             |
+     +--->| SDI   AD7944   SDO |-------->| SDI         |
+          |        SCK         |         |             |
+          +--------------------+         |             |
+                    ^                    |             |
+                    +--------------------| SCLK        |
+                                         +-------------+
+
+To select this mode in the device tree, set the ``adi,spi-mode`` property to
+``"single"`` and omit the ``cnv-gpios`` property.
+
+CS mode, 4-wire, without busy indicator
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code-block::
+
+                                         +-------------+
+     +-----------------------------------| CS          |
+     |                                   |             |
+     |              +--------------------| GPIO        |
+     |              v                    |             |
+     |    +--------------------+         |     HOST    |
+     |    |        CNV         |         |             |
+     +--->| SDI   AD7944   SDO |-------->| SDI         |
+          |        SCK         |         |             |
+          +--------------------+         |             |
+                    ^                    |             |
+                    +--------------------| SCLK        |
+                                         +-------------+
+
+To select this mode in the device tree, omit the ``adi,spi-mode`` property and
+provide the ``cnv-gpios`` property.
+
+Reference voltage
+-----------------
+
+All 3 possible reference voltage sources are supported:
+
+- Internal reference
+- External 1.2V 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
+----------------------
+
+- ``BUSY`` indication
+- ``TURBO`` mode
+- Daisy chain mode
+
+
+Device attributes
+=================
+
+There are two types of ADCs in this family, pseudo-differential and fully
+differential. The channel name is different depending on the type of ADC.
+
+Pseudo-differential ADCs
+------------------------
+
+AD7944 and AD7985 are pseudo-differential ADCs and have the following attributes:
+
++---------------------------------------+--------------------------------------------------------------+
+| Attribute                             | Description                                                  |
++=======================================+==============================================================+
+| ``in_voltage0_raw``                   | Raw ADC voltage value (*IN+* referenced to ground sense).    |
++---------------------------------------+--------------------------------------------------------------+
+| ``in_voltage0_scale``                 | Scale factor to convert raw value to mV.                     |
++---------------------------------------+--------------------------------------------------------------+
+
+Fully-differential ADCs
+-----------------------
+
+AD7986 is a fully-differential ADC and has the following attributes:
+
++---------------------------------------+--------------------------------------------------------------+
+| Attribute                             | Description                                                  |
++=======================================+==============================================================+
+| ``in_voltage0-voltage1_raw``          | Raw ADC voltage value (*IN+* - *IN-*).                       |
++---------------------------------------+--------------------------------------------------------------+
+| ``in_voltage0-voltage1_scale``        | Scale factor to convert raw value to mV.                     |
++---------------------------------------+--------------------------------------------------------------+
+
+
+Device buffers
+==============
+
+This driver supports IIO triggered buffers.
+
+See :doc:`iio_devbuf` for more information.
diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst
index 30b09eefe75e..fb6f9d743211 100644
--- a/Documentation/iio/index.rst
+++ b/Documentation/iio/index.rst
@@ -16,6 +16,7 @@ Industrial I/O Kernel Drivers
 .. toctree::
    :maxdepth: 1
 
+   ad7944
    adis16475
    bno055
    ep93xx_adc
diff --git a/MAINTAINERS b/MAINTAINERS
index fb2377bad376..40813d9ec38f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -448,6 +448,7 @@ R:	David Lechner <dlechner@baylibre.com>
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad7944.yaml
+F:	Documentation/iio/ad7944.rst
 F:	drivers/iio/adc/ad7944.c
 
 ADAFRUIT MINI I2C GAMEPAD

-- 
2.43.2

Re: [PATCH v2 0/2] docs: iio: new docs for ad7944 driver

[Jonathan Cameron]

On Fri, 22 Mar 2024 16:52:12 -0500
David Lechner <dlechner@baylibre.com> wrote:

> Adding documentation for the recently applied ad7944 driver.
> 
> Note: this also covers the features added in [1] that hasn't been
> applied yet.
> 
> [1]: https://lore.kernel.org/linux-iio/20240311-mainline-ad7944-3-wire-mode-v1-1-8e8199efa1f7@baylibre.com/
> 
> Also updating the MAINTAINERS file to catch iio documentation since this
> seems to have been overlooked.
> 
There goes deniability :)

Applied to the togreg-normal branch of iio.git.

Thanks,

Jonathan

> ---
> Changes in v2:
> - Removed some paragraphs that would be redundant for most drivers,
>   e.g. most of the buffer section.
> - Link to v1: https://lore.kernel.org/r/20240313-mainline-ad7944-doc-v1-0-7860416726e4@baylibre.com
> 
> ---
> David Lechner (2):
>       MAINTAINERS: add Documentation/iio/ to IIO subsystem
>       docs: iio: new docs for ad7944 driver
> 
>  Documentation/iio/ad7944.rst | 130 +++++++++++++++++++++++++++++++++++++++++++
>  Documentation/iio/index.rst  |   1 +
>  MAINTAINERS                  |   2 +
>  3 files changed, 133 insertions(+)
> ---
> base-commit: bbafdb305d6b00934cc09a90ec1bb659d43e5171
> change-id: 20240313-mainline-ad7944-doc-285b47ed6d35