drivers/adc: add Gecko IADC driver

This commit adds the Gecko IADC driver and support for it to the
efr32bg_sltb010a board.

Signed-off-by: Mateusz Sierszulski <msierszulski@antmicro.com>
Signed-off-by: Roman Dobrodii <rdobrodii@antmicro.com>

Author: msierszulski

boards/arm/efr32_thunderboard/thunderboard.dtsi

@@ -128,3 +128,7 @@
 	location-scl = <GECKO_LOCATION(3) GECKO_PORT_D GECKO_PIN(3)>;
 	status = "okay";
 };
+
+&adc0 {
+	status = "okay";
+};

drivers/adc/CMakeLists.txt

@@ -32,3 +32,4 @@ zephyr_library_sources_ifdef(CONFIG_ADC_ADS7052		adc_ads7052.c)
 zephyr_library_sources_ifdef(CONFIG_ADC_RPI_PICO	adc_rpi_pico.c)
 zephyr_library_sources_ifdef(CONFIG_ADC_XMC4XXX		adc_xmc4xxx.c)
 zephyr_library_sources_ifdef(CONFIG_ADC_ESP32		adc_esp32.c)
+zephyr_library_sources_ifdef(CONFIG_ADC_GECKO   	iadc_gecko.c)

drivers/adc/Kconfig

@@ -90,4 +90,6 @@ source "drivers/adc/Kconfig.rpi_pico"
 
 source "drivers/adc/Kconfig.xmc4xxx"
 
+source "drivers/adc/Kconfig.gecko"
+
 endif # ADC

drivers/adc/Kconfig.gecko

@@ -0,0 +1,13 @@
+# IADC configuration options
+
+# Copyright (c) 2023 Antmicro <www.antmicro.com>
+# SPDX-License-Identifier: Apache-2.0
+
+config ADC_GECKO
+	bool "Gecko Incremental ADC driver"
+	default y
+	depends on DT_HAS_SILABS_GECKO_IADC_ENABLED
+	select SOC_GECKO_IADC
+	select ADC_CONFIGURABLE_INPUTS
+	help
+	  Enable the driver implementation for the Silabs GeckoEXX32 Incremental ADC