iio: vadc: Qualcomm SPMI PMIC voltage ADC driver

The voltage ADC is peripheral of Qualcomm SPMI PMIC chips. It has
15bits resolution and register space inside PMIC accessible across
SPMI bus.

The vadc driver registers itself through IIO interface.

Signed-off-by: Stanimir Varbanov <svarbanov@mm-sol.com>
Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 0f79e47..311829a 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -228,6 +228,20 @@
 	  To compile this driver as a module, choose M here: the module will
 	  be called qcom-spmi-iadc.
 
+config QCOM_SPMI_VADC
+	tristate "Qualcomm SPMI PMIC voltage ADC"
+	depends on SPMI
+	select REGMAP_SPMI
+	help
+	  This is the IIO Voltage ADC driver for Qualcomm QPNP VADC Chip.
+
+	  The driver supports multiple channels read. The VADC is a 15-bit
+	  sigma-delta ADC. Some of the channels are internally used for
+	  calibration.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called qcom-spmi-vadc.
+
 config ROCKCHIP_SARADC
 	tristate "Rockchip SARADC driver"
 	depends on ARCH_ROCKCHIP || (ARM && COMPILE_TEST)