iio: dac: Add MAX22007 DAC driver support

Add support for the MAX22007 4 channel DAC
that drives a voltage or current output on each channel.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>

Author: jansunil

Documentation/ABI/testing/sysfs-bus-iio-dac-max22007

@@ -0,0 +1,33 @@
+What:		/sys/bus/iio/devices/iio:deviceX/out_voltageY_ldac_update
+KernelVersion:	6.13
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Trigger LDAC (Load DAC) update for the specified channel. Write 1 to update DAC outputs.
+
+What:		/sys/bus/iio/devices/iio:deviceX/out_currentY_ldac_update
+KernelVersion:	6.13
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Trigger LDAC (Load DAC) update for the specified channel.
+		Writing 1 will transfer the DAC register value to the actual
+		DAC output, effectively updating the analog output current.
+		Writing 0 has no effect. This is useful when using the
+		transparent latch mode is disabled, allowing manual control
+		over when DAC register changes take effect on the output.
+
+What:		/sys/bus/iio/devices/iio:deviceX/out_voltageY_powermode
+What:		/sys/bus/iio/devices/iio:deviceX/out_currentY_powermode
+KernelVersion:	6.13
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Control the power state of the specified channel. Write "on" to
+		enable the channel output, or "off" to disable it. Reading
+		returns the current power state.
+
+What:		/sys/bus/iio/devices/iio:deviceX/out_voltageY_powermode_available
+What:		/sys/bus/iio/devices/iio:deviceX/out_currentY_powermode_available
+KernelVersion:	6.13
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Shows the available power modes for the channel. Always returns
+		"on off".

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 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices MAX22007
+ *
+ * hdl_project: <max22007_rpi>
+ *
+ * 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>;
+			adi,dac-latch-mode = "ldac-control";
+			adi,mode = "voltage";
+		};
+
+		channel@1 {
+			reg = <1>;
+			adi,dac-latch-mode = "ldac-control";
+			adi,mode = "voltage";
+		};
+
+		channel@2 {
+			reg = <2>;
+			adi,dac-latch-mode = "ldac-control";
+			adi,mode = "voltage";
+		};
+
+		channel@3 {
+			reg = <3>;
+			adi,dac-latch-mode = "ldac-control";
+			adi,mode = "voltage";
+		};
+	};
+};
+
+&spidev0 {
+	status = "disabled";
+};
+
+&spidev1 {
+	status = "disabled";
+};

drivers/iio/dac/Kconfig

@@ -472,6 +472,19 @@ config MAX517
 	  This driver can also be built as a module.  If so, the module
 	  will be called max517.
 
+config MAX22007
+	tristate "Analog Devices MAX22007 DAC Driver"
+	depends on SPI
+	select REGMAP
+	select CRC8
+	help
+	  Say Y here if you want to build a driver for Analog Devices MAX22007.
+
+	  MAX22007 is a single-channel, 16-bit, voltage-output digital to
+	  analog converter (DAC) with SPI interface.
+
+	  If compiled as a module, it will be called max22007.
+
 config MAX5522
 	tristate "Maxim MAX5522 DAC driver"
 	depends on SPI_MASTER

drivers/iio/dac/Makefile

@@ -46,6 +46,7 @@ obj-$(CONFIG_LTC2664) += ltc2664.o
 obj-$(CONFIG_LTC2688) += ltc2688.o
 obj-$(CONFIG_M62332) += m62332.o
 obj-$(CONFIG_MAX517) += max517.o
+obj-$(CONFIG_MAX22007) += max22007.o
 obj-$(CONFIG_MAX5522) += max5522.o
 obj-$(CONFIG_MAX5821) += max5821.o
 obj-$(CONFIG_MCP4725) += mcp4725.o