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Message-ID: <20251219-max22007-dev-v1-2-242da2c2b868@analog.com>
Date: Fri, 19 Dec 2025 16:31:16 +0100
From: Janani Sunil <janani.sunil@...log.com>
To: Lars-Peter Clausen <lars@...afoo.de>,
Michael Hennerich
<Michael.Hennerich@...log.com>,
Alexandru Ardelean
<alexandru.ardelean@...log.com>,
Jonathan Cameron <jic23@...nel.org>, "Rob
Herring" <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
"Conor
Dooley" <conor+dt@...nel.org>,
Jonathan Corbet <corbet@....net>
CC: <linux-iio@...r.kernel.org>, <devicetree@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
Janani Sunil
<janani.sunil@...log.com>
Subject: [PATCH 2/3] docs: iio: Add documentation for MAX22007 driver
Add documentation for MAX22007 driver which describes how the user
can access the driver using dtoverlays
Signed-off-by: Janani Sunil <janani.sunil@...log.com>
---
Documentation/iio/index.rst | 1 +
Documentation/iio/max22007.rst | 145 +++++++++++++++++++++++++++++++++++++++++
MAINTAINERS | 1 +
3 files changed, 147 insertions(+)
diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst
index 315ae37d6fd4..7601bc2882e7 100644
--- a/Documentation/iio/index.rst
+++ b/Documentation/iio/index.rst
@@ -37,4 +37,5 @@ Industrial I/O Kernel Drivers
adxl345
bno055
ep93xx_adc
+ max22007
opt4060
diff --git a/Documentation/iio/max22007.rst b/Documentation/iio/max22007.rst
new file mode 100644
index 000000000000..e04c563f1fd0
--- /dev/null
+++ b/Documentation/iio/max22007.rst
@@ -0,0 +1,145 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+===============
+MAX22007 driver
+===============
+
+Device driver for Analog Devices Inc. MAX22007 quad-channel industrial DAC.
+The module name is ``max22007``.
+
+Supported devices
+=================
+
+* `MAX22007 <https://www.analog.com/en/products/max22007.html>`_
+
+Wiring connections
+==================
+
+The MAX22007 uses a standard SPI interface.
+
+Device Tree Configuration
+=========================
+
+The device supports both global and per-channel configuration through device tree.
+
+Global Properties:
+
+* ``reset-gpios``: GPIO pin for hardware reset (optional, falls back to
+ software reset if not specified)
+* ``vdd-supply``: Low-Voltage Power Supply from +2.7V to +5.5V (optional)
+* ``hvdd-supply``: Positive High-Voltage Power Supply from +8V to (HVSS +24V)
+ for the Output Channels (optional)
+* ``hvss-supply``: Negative High-Voltage Power Supply from -2V to 0V for the
+ Output Channels (optional)
+
+Per-channel properties:
+
+* ``adi,type``: Specify the channel output type - must be either "voltage" or "current" (mandatory)
+
+Note: The driver operates in transparent mode (immediate register-to-output updates).
+Channel mode is determined by the ``adi,type`` property:
+
+* ``adi,type = "current"``: the channel operates in current mode
+* ``adi,type = "voltage"``: the channel operates in voltage mode
+
+Device attributes
+=================
+
+The MAX22007 driver provides IIO DAC interfaces that vary based on the
+configured channel mode. Each channel appears as a separate IIO device
+attribute:
+
+* ``out_voltage_raw`` (voltage mode channels)
+* ``out_current_raw`` (current mode channels)
+* ``out_voltage_scale`` / ``out_current_scale`` (channel scaling factors)
+* ``out_voltage_powerdown`` / ``out_current_powerdown`` (channel power control)
+
+The driver automatically configures the IIO channel type based on the configured
+channel mode from device tree.
+
+Power Mode Control
+==================
+
+Each channel provides standard IIO ``powerdown`` attributes for runtime power
+control:
+
+* Write ``1`` to power down (disable) the channel output
+* Write ``0`` to power up (enable) the channel output
+* Read the attribute to get the current power state (1=powered down, 0=powered up)
+
+This allows individual channels to be powered on/off independently for power
+management and safety purposes.
+
+Usage Examples
+==============
+
+Setting DAC output values:
+
+.. code-block:: bash
+
+ # Set channel 0 (voltage mode) to raw value 655 (≈2V)
+ # Output is updated immediately in transparent mode
+ echo 655 > /sys/bus/iio/devices/iio:deviceX/out_voltage0_raw
+
+ # Set channel 1 (current mode)
+ # Output is updated immediately in transparent mode
+ echo 1024 > /sys/bus/iio/devices/iio:deviceX/out_current1_raw
+
+Controlling channel power modes:
+
+.. code-block:: bash
+
+ # Enable channel 0 (power up)
+ echo 0 > /sys/bus/iio/devices/iio:deviceX/out_voltage0_powerdown
+
+ # Disable channel 1 (power down)
+ echo 1 > /sys/bus/iio/devices/iio:deviceX/out_current1_powerdown
+
+ # Check current power state (0=powered up, 1=powered down)
+ cat /sys/bus/iio/devices/iio:deviceX/out_voltage0_powerdown
+
+Reading channel values and scale factors:
+
+.. code-block:: bash
+
+ # Read raw DAC value
+ cat /sys/bus/iio/devices/iio:deviceX/out_voltage0_raw
+
+ # Read scale factor (volts per LSB)
+ cat /sys/bus/iio/devices/iio:deviceX/out_voltage0_scale
+
+Check available channels:
+
+.. code-block:: bash
+
+ ls /sys/bus/iio/devices/iio:deviceX/out_*_raw
+
+Scale Calculations
+==================
+
+The driver provides accurate scale factors based on the hardware configuration:
+
+**Voltage Mode:**
+
+- Scale = (5 × 2.5V) / 4096 = 0.003051757 V per LSB
+- Range: 0V to 12.5V over 12-bit (0-4095)
+- Formula: Output = Raw_Value × Scale
+
+**Current Mode:**
+
+- Scale = (2.5V / (2 × 50Ω)) / 4096 = 0.000006103515625 A per LSB
+- Range: 0A to 0.025A over 12-bit (0-4095)
+- Formula: Output = Raw_Value × Scale
+
+Driver Architecture
+===================
+
+The driver implements:
+
+* **CRC8 Error Checking**: Always-enabled CRC8 for SPI data integrity
+* **Channel Configuration**: Supports per-channel mode and power configuration
+
+Channel configuration (voltage/current mode) is set via the ``adi,type``
+device tree property and cannot be changed dynamically The driver requires
+proper device tree configuration with mandatory ``adi,type`` property for each
+channel.
diff --git a/MAINTAINERS b/MAINTAINERS
index e1addbd21562..6561455732c9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1599,6 +1599,7 @@ L: linux-iio@...r.kernel.org
S: Supported
W: https://ez.analog.com/linux-software-drivers
F: Documentation/devicetree/bindings/iio/dac/adi,max22007.yaml
+F: Documentation/iio/max22007.rst
ANALOG DEVICES INC ADA4250 DRIVER
M: Antoniu Miclaus <antoniu.miclaus@...log.com>
--
2.43.0
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