Max22007 dev

Documentation/devicetree/bindings/iio/dac/adi,max22007.yaml

@@ -0,0 +1,116 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/dac/adi,max22007.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices MAX22007 DAC device driver
+
+maintainers:
+  - Janani Sunil <janani.sunil@analog.com>
+
+description:
+  The MAX22007 is a quad-channel, 12-bit digital-to-analog converter (DAC)
+  with integrated precision output amplifiers and current output capability.
+  Each channel can be independently configured for voltage or current output.
+  Datasheet available at https://www.analog.com/en/products/max22007.html
+
+$ref: /schemas/spi/spi-peripheral-props.yaml#
+
+properties:
+  compatible:
+    const: adi,max22007
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency:
+    maximum: 500000
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+  vdd-supply:
+    description: Low-Voltage Power Supply from +2.7V to +5.5V.
+
+  hvdd-supply:
+    description:
+      Positive High-Voltage Power Supply from +8V to (HVSS +24V) for
+      the Output Channels.
+
+  hvss-supply:
+    description:
+      Negative High-Voltage Power Supply from -2V to 0V for the Output Channels.
+
+
+  reset-gpios:
+    maxItems: 1
+    description:
+      GPIO used for hardware reset of the device.
+
+patternProperties:
+  "^channel@[0-3]$":
+    allOf:
+      - $ref: /schemas/iio/dac/dac.yaml#
+      - type: object
+        description:
+          Represents the external channels which are connected to the DAC.
+          Channels not specified in the device tree will be powered off.
+
+        properties:
+          reg:
+            description: Channel number
+            maxItems: 1
+
+          output-range-microamp:
+            type: array
+            items:
+              type: integer
+            minItems: 2
+            maxItems: 2
+            description: Min and max output range in microamps.
+
+        unevaluatedProperties: false
+
+required:
+  - compatible
+  - reg
+
+anyOf:
+  - required: [channel@0]
+  - required: [channel@1]
+  - required: [channel@2]
+  - required: [channel@3]
+
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        dac@0 {
+            compatible = "adi,max22007";
+            reg = <0>;
+            spi-max-frequency = <500000>;
+            reset-gpios = <&gpio 19 GPIO_ACTIVE_LOW>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            channel@0 {
+                reg = <0>;
+            };
+
+            channel@1 {
+                reg = <1>;
+                output-range-microamp = <0 25000>;
+            };
+        };
+    };
+...

Documentation/iio/index.rst

@@ -31,3 +31,4 @@ Industrial I/O Kernel Drivers
    adxl380
    bno055
    ep93xx_adc
+   max22007

Documentation/iio/max22007.rst

@@ -0,0 +1,197 @@
+.. 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:
+* ``output-range-microvolt``: Specify the channel output range in microvolts for voltage mode channels
+* ``output-range-microamp``: Specify the channel output range in microamperes for current mode channels
+
+Note: The driver operates in transparent mode (immediate register-to-output updates).
+Channel mode is determined by the presence of output-range properties:
+- If ``output-range-microamp`` is present, the channel operates in current mode
+- Otherwise, the channel defaults to 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)
+* ``crc_enable`` (device-wide CRC8 error checking 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.
+
+CRC Control
+===========
+
+The driver provides runtime control over SPI CRC8 error checking through the
+``crc_enable`` attribute:
+
+* Write ``1`` to enable CRC8 error checking for data integrity (default)
+* Write ``0`` to disable CRC8 checking for improved performance
+* Read the attribute to get the current CRC state (1=enabled, 0=disabled)
+
+CRC is enabled by default at driver initialization to ensure data integrity,
+but can be disabled at runtime if needed for performance optimization.
+
+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
+
+Controlling CRC error checking:
+
+.. code-block:: bash
+
+    # Enable CRC8 checking (default)
+    echo 1 > /sys/bus/iio/devices/iio:deviceX/crc_enable
+
+    # Disable CRC8 checking for performance
+    echo 0 > /sys/bus/iio/devices/iio:deviceX/crc_enable
+
+    # Check current CRC state (1=enabled, 0=disabled)
+    cat /sys/bus/iio/devices/iio:deviceX/crc_enable
+
+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
+
+Register Map
+------------
+
+The MAX22007 uses the following register mapping:
+
+.. list-table::
+   :header-rows: 1
+
+   * - Address
+     - Register Name
+     - Description
+   * - 0x03
+     - CONFIG_REG
+     - Configuration register (CRC enable, DAC latch modes)
+   * - 0x04
+     - CONTROL_REG
+     - LDAC control register for runtime updates
+   * - 0x05
+     - CHANNEL_MODE_REG
+     - Channel mode and power control
+   * - 0x06
+     - SOFT_RESET_REG
+     - Software reset control
+   * - 0x07-0x0A
+     - DAC_CHANNEL_REG(0-3)
+     - DAC data registers for channels 0-3
+
+
+Driver Architecture
+===================
+
+The driver implements the following key features:
+
+* **CRC8 Error Checking**: Runtime configurable CRC8 for SPI data integrity (enabled by default)
+* **Channel Configuration**: Supports per-channel mode and power configuration
+* **Register Map**: Uses regmap for efficient register access and caching
+* **IIO Integration**: Full integration with the Linux IIO subsystem
+
+Not Implemented
+===============
+
+* Channel configuration (voltage/current mode) is set at device tree parsing
+  and cannot be changed dynamically
+* The driver requires proper device tree configuration for optimal operation
+* Simultaneous multi-channel LDAC updates (only single-channel updates supported)

arch/arm/boot/dts/overlays/Makefile

@@ -322,6 +322,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
 	rpi-ltc6952.dtbo \
 	rpi-max14830-i2c.dtbo \
 	rpi-max14830-spi.dtbo \
+	rpi-max22007.dtbo \
 	rpi-max31335.dtbo \
 	rpi-poe.dtbo \
 	rpi-poe-plus.dtbo \

arch/arm/boot/dts/overlays/rpi-max22007-overlay.dts

@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices MAX22007
+ *
+ * Copyright (C) 2025 Analog Devices Inc.
+ */
+
+/dts-v1/;
+/plugin/;
+
+#include <dt-bindings/gpio/gpio.h>
+
+&spi0 {
+	status = "okay";
+
+	max22007: max22007@0 {
+		compatible = "adi,max22007";
+		reg = <0>;
+		spi-max-frequency = <500000>;
+		spi-cpha;
+		spi-cpol;
+		status = "okay";
+		reset-gpios = <&gpio 19 GPIO_ACTIVE_LOW>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		channel@0 {
+			reg = <0>;
+		};
+
+		channel@1 {
+			reg = <1>;
+			output-range-microamp = <0 25000>;
+		};
+
+		channel@2 {
+			reg = <2>;
+		};
+
+		channel@3 {
+			reg = <3>;
+		};
+	};
+};
+
+&spidev0 {
+	status = "disabled";
+};
+
+&spidev1 {
+	status = "disabled";
+};