linux-kernel - [PATCH 3/4] docs: iio: new docs for ad4052 driver

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Message-ID: <20250306-iio-driver-ad4052-v1-3-2badad30116c@analog.com>
Date: Thu, 6 Mar 2025 15:03:16 +0100
From: Jorge Marques <jorge.marques@...log.com>
To: Jonathan Cameron <jic23@...nel.org>, Lars-Peter Clausen <lars@...afoo.de>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Rob Herring
	<robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
	<conor+dt@...nel.org>, Jonathan Corbet <corbet@....net>,
        David Lechner
	<dlechner@...libre.com>
CC: <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        Jorge Marques
	<jorge.marques@...log.com>
Subject: [PATCH 3/4] docs: iio: new docs for ad4052 driver

This adds a new page to document how to use the ad4052 ADC driver.

Signed-off-by: Jorge Marques <jorge.marques@...log.com>
---
 Documentation/iio/ad4052.rst | 93 ++++++++++++++++++++++++++++++++++++++++++++
 MAINTAINERS                  |  1 +
 2 files changed, 94 insertions(+)

diff --git a/Documentation/iio/ad4052.rst b/Documentation/iio/ad4052.rst
new file mode 100644
index 0000000000000000000000000000000000000000..cf0cbd60d0a48ea52f74ea02fde659fcdba61aa1
--- /dev/null
+++ b/Documentation/iio/ad4052.rst
@@ -0,0 +1,93 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+=============
+AD4052 driver
+=============
+
+ADC driver for Analog Devices Inc. AD4052 and similar devices.
+The module name is ``ad4052``.
+
+Supported devices
+=================
+
+The following chips are supported by this driver:
+
+* `AD4050 <https://www.analog.com/AD4050>`_
+* `AD4052 <https://www.analog.com/AD4052>`_
+* `AD4056 <https://www.analog.com/AD4056>`_
+* `AD4058 <https://www.analog.com/AD4058>`_
+
+Wiring modes
+============
+
+The ADC uses SPI 4-wire mode, and contain two programmable GPIOs and
+a CNV pin.
+
+The CNV pin is exposed as the ``cnv-gpios`` and triggers a ADC conversion.
+GP1 is ADC conversion ready signal and GP0 Threshold event interrupt, both
+exposed as interrupts.
+
+Omit ``cnv-gpios`` and tie CNV and CS together to use the rising edge
+of the CS as the CNV signal.
+
+Device attributes
+=================
+
+The ADC contain only one channels, and the following attributes:
+
+.. list-table:: Driver attributes
+   :header-rows: 1
+
+   * - Attribute
+     - Description
+   * - ``in_voltage0_raw``
+     - Raw ADC voltage value
+   * - ``in_voltage0_oversampling_ratio``
+     - Enable the device's burst averaging mode to over sample using
+       the internal sample rate.
+   * - ``in_voltage0_oversampling_ratio_available``
+     - List of available oversampling values. Value 0 disable the burst
+       averaging mode.
+   * - ``sample_rate``
+     - Device internal sample rate used in the burst averaging mode.
+   * - ``sample_rate_available``
+     - List of available sample rates.
+
+Threshold events
+================
+
+The ADC supports a monitoring mode to raise threshold events.
+The driver supports a single interrupt for both rising and falling
+readings.
+
+During monitor mode, the device is busy since other transactions
+require to put the device in configuration mode first.
+
+Low-power mode
+==============
+
+The device enters low-power mode on idle to save power.
+Enabling an event puts the device out of the low-power since the ADC
+autonomously samples to assert the event condition.
+
+SPI offload support
+===================
+
+To be able to achieve the maximum sample rate, the driver can be used with the
+`AXI SPI Engine`_ to provide SPI offload support.
+
+.. _AXI SPI Engine: http://analogdevicesinc.github.io/hdl/projects/ad4052_ardz/index.html
+
+When SPI offload is being used, additional attributes are present:
+
+.. list-table:: Additional attributes
+   :header-rows: 1
+
+   * - Attribute
+     - Description
+   * - ``in_voltage0_sampling_frequency``
+     - Set the sampling frequency.
+   * - ``in_voltage0_sampling_frequency_available``
+     - Get the sampling frequency range.
+
+The scan type is different when the buffer with offload support is enabled.
diff --git a/MAINTAINERS b/MAINTAINERS
index fef8adaee888d59e1aa3b3592dda5a8bea0b7677..312b2cf94b8f06298b1cbe5975ee32e2cf9a74d8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1322,6 +1322,7 @@ M:	Jorge Marques <jorge.marques@...log.com>
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad4052.yaml
+F:	Documentation/iio/ad4052.rst
 
 ANALOG DEVICES INC AD4130 DRIVER
 M:	Cosmin Tanislav <cosmin.tanislav@...log.com>

-- 
2.48.1