iio: dac: ad3530r: Add driver for AD3530R and AD3531R

The AD3530/AD3530R (8-channel) and AD3531/AD3531R (4-channel) are
low-power, 16-bit, buffered voltage output DACs with software-
programmable gain controls, providing full-scale output spans of 2.5V or
5V for reference voltages of 2.5V. These devices operate from a single
2.7V to 5.5V supply and are guaranteed monotonic by design. The "R"
variants include a 2.5V, 5ppm/°C internal reference, which is disabled
by default.

Support for monitoring internal die temperature, output voltages, and
current of a selected channel via the MUXOUT pin using an external ADC
is currently not implemented.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Kim Seer Paller <kimseer.paller@analog.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Link: https://patch.msgid.link/20250429-togreg-v7-3-0af9c543b545@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

MAINTAINERS

@@ -1306,6 +1306,7 @@ L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/dac/adi,ad3530r.yaml
+F:	drivers/iio/dac/ad3530r.c
 
 ANALOG DEVICES INC AD3552R DRIVER
 M:	Nuno Sá <nuno.sa@analog.com>

drivers/iio/dac/Kconfig

@@ -6,6 +6,17 @@
 
 menu "Digital to analog converters"
 
+config AD3530R
+	tristate "Analog Devices AD3530R and Similar DACs driver"
+	depends on SPI
+	select REGMAP_SPI
+	help
+	  Say yes here to build support for Analog Devices AD3530R, AD3531R
+	  Digital to Analog Converter.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad3530r.
+
 config AD3552R_HS
 	tristate "Analog Devices AD3552R DAC High Speed driver"
 	select AD3552R_LIB

drivers/iio/dac/Makefile

@@ -4,6 +4,7 @@
 #
 
 # When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_AD3530R) += ad3530r.o
 obj-$(CONFIG_AD3552R_HS) += ad3552r-hs.o
 obj-$(CONFIG_AD3552R_LIB) += ad3552r-common.o
 obj-$(CONFIG_AD3552R) += ad3552r.o