iio: adc: Add basic support for AD4170-4

The AD4170-4 is a multichannel, low noise, 24-bit precision sigma-delta
analog to digital converter. The AD4170-4 design offers a flexible data
acquisition solution with crosspoint multiplexed analog inputs,
configurable ADC voltage reference inputs, ultra-low noise integrated PGA,
digital filtering, wide range of configurable output data rates, internal
oscillator and temperature sensor, four GPIOs, and integrated features for
interfacing with load cell weigh scales, RTD, and thermocouple sensors.

Add basic support for the AD4170-4 ADC with the following features:
- Single-shot read.
- Analog front end PGA configuration.
- Differential and pseudo-differential input configuration.

Signed-off-by: Ana-Maria Cusco <ana-maria.cusco@analog.com>
Co-developed-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Link: https://patch.msgid.link/ce3fd150bd63a2aed6eb6fe59aad6d60c0f9fb67.1751895245.git.marcelo.schmitt@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: acusco

MAINTAINERS

@@ -1398,6 +1398,7 @@ L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad4170-4.yaml
+F:	drivers/iio/adc/ad4170-4.c
 
 ANALOG DEVICES INC AD4695 DRIVER
 M:	Michael Hennerich <michael.hennerich@analog.com>

drivers/iio/adc/Kconfig

@@ -84,6 +84,18 @@ config AD4130
 	  To compile this driver as a module, choose M here: the module will be
 	  called ad4130.
 
+
+config AD4170_4
+	tristate "Analog Device AD4170-4 ADC Driver"
+	depends on SPI
+	select REGMAP_SPI
+	help
+	  Say yes here to build support for Analog Devices AD4170-4 SPI analog
+	  to digital converters (ADC).
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called ad4170-4.
+
 config AD4695
 	tristate "Analog Device AD4695 ADC Driver"
 	depends on SPI

drivers/iio/adc/Makefile

@@ -12,6 +12,7 @@ obj-$(CONFIG_AD4000) += ad4000.o
 obj-$(CONFIG_AD4030) += ad4030.o
 obj-$(CONFIG_AD4080) += ad4080.o
 obj-$(CONFIG_AD4130) += ad4130.o
+obj-$(CONFIG_AD4170_4) += ad4170-4.o
 obj-$(CONFIG_AD4695) += ad4695.o
 obj-$(CONFIG_AD4851) += ad4851.o
 obj-$(CONFIG_AD7091R) += ad7091r-base.o