From: David Lechner <dlechner@baylibre.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: "David Lechner" <dlechner@baylibre.com>,
"Michael Hennerich" <Michael.Hennerich@analog.com>,
"Nuno Sá" <nuno.sa@analog.com>,
"Jonathan Corbet" <corbet@lwn.net>,
linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org
Subject: [PATCH 2/2] docs: iio: ad7944: add documentation for chain mode
Date: Thu, 25 Apr 2024 09:10:00 -0500 [thread overview]
Message-ID: <20240425-iio-ad7944-chain-mode-v1-2-9d9220ff21e1@baylibre.com> (raw)
In-Reply-To: <20240425-iio-ad7944-chain-mode-v1-0-9d9220ff21e1@baylibre.com>
Add documentation for chain mode support that was recently added to the
AD7944 ADC driver.
Signed-off-by: David Lechner <dlechner@baylibre.com>
---
Documentation/iio/ad7944.rst | 30 ++++++++++++++++++++++++++++--
1 file changed, 28 insertions(+), 2 deletions(-)
diff --git a/Documentation/iio/ad7944.rst b/Documentation/iio/ad7944.rst
index f418ab1288ae..0d26e56aba88 100644
--- a/Documentation/iio/ad7944.rst
+++ b/Documentation/iio/ad7944.rst
@@ -24,7 +24,7 @@ Supported features
SPI wiring modes
----------------
-The driver currently supports two of the many possible SPI wiring configurations.
+The driver currently supports three of the many possible SPI wiring configurations.
CS mode, 3-wire, without busy indicator
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -68,6 +68,27 @@ CS mode, 4-wire, without busy indicator
To select this mode in the device tree, omit the ``adi,spi-mode`` property and
provide the ``cnv-gpios`` property.
+Chain mode, without busy indicator
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code-block::
+
+ +-------------+
+ +-------------------------+--------------------| CS |
+ v v | |
+ +--------------------+ +--------------------+ | HOST |
+ | CNV | | CNV | | |
+ +--->| SDI AD7944 SDO |--->| SDI AD7944 SDO |-------->| SDI |
+ | | SCK | | SCK | | |
+ GND +--------------------+ +--------------------+ | |
+ ^ ^ | |
+ +-------------------------+--------------------| SCLK |
+ +-------------+
+
+To select this mode in the device tree, set the ``adi,spi-mode`` property to
+``"chain"``, add the ``spi-cs-high`` flag, add the ``#daisy-chained-devices``
+property, and omit the ``cnv-gpios`` property.
+
Reference voltage
-----------------
@@ -86,7 +107,6 @@ Unimplemented features
- ``BUSY`` indication
- ``TURBO`` mode
-- Daisy chain mode
Device attributes
@@ -108,6 +128,9 @@ AD7944 and AD7985 are pseudo-differential ADCs and have the following attributes
| ``in_voltage0_scale`` | Scale factor to convert raw value to mV. |
+---------------------------------------+--------------------------------------------------------------+
+In "chain" mode, additional chips will appear as additional voltage input
+channels, e.g. ``in_voltage1_raw``.
+
Fully-differential ADCs
-----------------------
@@ -121,6 +144,9 @@ AD7986 is a fully-differential ADC and has the following attributes:
| ``in_voltage0-voltage1_scale`` | Scale factor to convert raw value to mV. |
+---------------------------------------+--------------------------------------------------------------+
+In "chain" mode, additional chips will appear as additional voltage input
+channels, e.g. ``in_voltage2-voltage3_raw``.
+
Device buffers
==============
--
2.43.2
prev parent reply other threads:[~2024-04-25 14:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-25 14:09 [PATCH 0/2] iio: adc: ad7944: implement chain mode support David Lechner
2024-04-25 14:09 ` [PATCH 1/2] iio: adc: ad7944: add support for chain mode David Lechner
2024-04-28 16:29 ` Jonathan Cameron
2024-04-25 14:10 ` David Lechner [this message]
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