iio: light: Added AMS tsl2591 driver implementation

Driver implementation for AMS/TAOS tsl2591 ambient light sensor.

This driver supports configuration via device tree and sysfs.
Supported channels for raw infrared light intensity,
raw combined light intensity and illuminance in lux.
The driver additionally supports iio events on lower and
upper thresholds.

This is a very-high sensitivity light-to-digital converter that
transforms light intensity into a digital signal.

Datasheet: https://ams.com/tsl25911#tab/documents
Signed-off-by: Joe Sandom <joe.g.sandom@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20210421221330.17007-1-joe.g.sandom@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/light/Kconfig

@@ -499,6 +499,17 @@ config TSL2583
 	  Provides support for the TAOS tsl2580, tsl2581 and tsl2583 devices.
 	  Access ALS data via iio, sysfs.
 
+config TSL2591
+        tristate "TAOS TSL2591 ambient light sensor"
+        depends on I2C
+        help
+          Select Y here for support of the AMS/TAOS TSL2591 ambient light sensor,
+          featuring channels for combined visible + IR intensity and lux illuminance.
+          Access data via iio and sysfs. Supports iio_events.
+
+          To compile this driver as a module, select M: the
+          module will be called tsl2591.
+
 config TSL2772
 	tristate "TAOS TSL/TMD2x71 and TSL/TMD2x72 Family of light and proximity sensors"
 	depends on I2C

drivers/iio/light/Makefile

@@ -48,6 +48,7 @@ obj-$(CONFIG_ST_UVIS25_SPI)	+= st_uvis25_spi.o
 obj-$(CONFIG_TCS3414)		+= tcs3414.o
 obj-$(CONFIG_TCS3472)		+= tcs3472.o
 obj-$(CONFIG_TSL2583)		+= tsl2583.o
+obj-$(CONFIG_TSL2591)		+= tsl2591.o
 obj-$(CONFIG_TSL2772)		+= tsl2772.o
 obj-$(CONFIG_TSL4531)		+= tsl4531.o
 obj-$(CONFIG_US5182D)		+= us5182d.o