iio: light: Add support for TI OPT4001 light sensor

This driver uses the continuous mode of the chip and integration
time can be configured through sysfs.
The constants for calculating lux value differs between packaging
so it uses different compatible string for the two versions
"ti,opt4001-picostar" and "ti,opt4001-sot-5x3" since the device id
is the same.

Datasheet: https://www.ti.com/lit/gpn/opt4001Signed-off-by: Stefan Windfeldt-Prytz <stefan.windfeldt-prytz@axis.com>
Link: https://lore.kernel.org/r/20230323-add-opt4001-driver-v3-2-62e121dab294@axis.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/light/Kconfig

@@ -413,6 +413,17 @@ config OPT3001
 	  If built as a dynamically linked module, it will be called
 	  opt3001.
 
+config OPT4001
+	tristate "Texas Instruments OPT4001 Light Sensor"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say Y or M here, you get support for Texas Instruments
+	  OPT4001 Ambient Light Sensor.
+
+	  If built as a dynamically linked module, it will be called
+	  opt4001.
+
 config PA12203001
 	tristate "TXC PA12203001 light and proximity sensor"
 	depends on I2C

drivers/iio/light/Makefile

@@ -37,6 +37,7 @@ obj-$(CONFIG_MAX44000)		+= max44000.o
 obj-$(CONFIG_MAX44009)		+= max44009.o
 obj-$(CONFIG_NOA1305)		+= noa1305.o
 obj-$(CONFIG_OPT3001)		+= opt3001.o
+obj-$(CONFIG_OPT4001)		+= opt4001.o
 obj-$(CONFIG_PA12203001)	+= pa12203001.o
 obj-$(CONFIG_ROHM_BU27034)	+= rohm-bu27034.o
 obj-$(CONFIG_RPR0521)		+= rpr0521.o