iio: light: Add support for Azoteq IQS621/622 ambient light sensors

This patch adds support for the Azoteq IQS621 and IQS622 ambient light
sensors, both of which can report a four-bit representation of ambient
light intensity.

The IQS621 can additionally report illuminace directly in units of lux,
while the IQS622 can report a four-bit representation of infrared light
intensity. Furthermore, the IQS622 can report a unitless measurement of
a target's proximity to the device.

Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/iio/light/Kconfig

@@ -173,6 +173,16 @@ config GP2AP020A00F
 	  To compile this driver as a module, choose M here: the
 	  module will be called gp2ap020a00f.
 
+config IQS621_ALS
+	tristate "Azoteq IQS621/622 ambient light sensors"
+	depends on MFD_IQS62X || COMPILE_TEST
+	help
+	  Say Y here if you want to build support for the Azoteq IQS621
+	  and IQS622 ambient light sensors.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called iqs621-als.
+
 config SENSORS_ISL29018
 	tristate "Intersil 29018 light and proximity sensor"
 	depends on I2C

drivers/iio/light/Makefile

@@ -21,6 +21,7 @@ obj-$(CONFIG_IIO_CROS_EC_LIGHT_PROX) += cros_ec_light_prox.o
 obj-$(CONFIG_GP2AP020A00F)	+= gp2ap020a00f.o
 obj-$(CONFIG_HID_SENSOR_ALS)	+= hid-sensor-als.o
 obj-$(CONFIG_HID_SENSOR_PROX)	+= hid-sensor-prox.o
+obj-$(CONFIG_IQS621_ALS)	+= iqs621-als.o
 obj-$(CONFIG_SENSORS_ISL29018)	+= isl29018.o
 obj-$(CONFIG_SENSORS_ISL29028)	+= isl29028.o
 obj-$(CONFIG_ISL29125)		+= isl29125.o