iio: adc: Add support for MediaTek MT6357/8/9 Auxiliary ADC

Add a driver to support reading the Auxiliary ADC IP found in the
MediaTek MT6357, MT6358 and MT6359 Power Management ICs, featuring
a different register layout, configuration reset and ADC reading
sequence from the other already supported MediaTek SoC or PMIC
(aux)ADC HW.

This driver provides multiple ADC channels for system monitoring,
such as battery voltage, PMIC temperature, PMIC-internal voltage
regulators temperature, and others.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Link: https://patch.msgid.link/20240604123008.327424-5-angelogioacchino.delregno@collabora.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/Kconfig

@@ -892,6 +892,18 @@ config MCP3911
 	  This driver can also be built as a module. If so, the module will be
 	  called mcp3911.
 
+config MEDIATEK_MT6359_AUXADC
+	tristate "MediaTek MT6359 PMIC AUXADC driver"
+	depends on MFD_MT6397
+	help
+	  Say yes here to enable support for MediaTek MT6357, MT6358 and
+	  MT6359 PMICs Auxiliary ADC.
+	  This driver provides multiple channels for system monitoring,
+	  such as battery voltage, PMIC temperature, and others.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called mt6359-auxadc.
+
 config MEDIATEK_MT6360_ADC
 	tristate "Mediatek MT6360 ADC driver"
 	depends on MFD_MT6360

drivers/iio/adc/Makefile

@@ -80,6 +80,7 @@ obj-$(CONFIG_MCP320X) += mcp320x.o
 obj-$(CONFIG_MCP3422) += mcp3422.o
 obj-$(CONFIG_MCP3564) += mcp3564.o
 obj-$(CONFIG_MCP3911) += mcp3911.o
+obj-$(CONFIG_MEDIATEK_MT6359_AUXADC) += mt6359-auxadc.o
 obj-$(CONFIG_MEDIATEK_MT6360_ADC) += mt6360-adc.o
 obj-$(CONFIG_MEDIATEK_MT6370_ADC) += mt6370-adc.o
 obj-$(CONFIG_MEDIATEK_MT6577_AUXADC) += mt6577_auxadc.o