staging: iio: light: Adding driver for ISL29018 ALS

adding support for the ISL 29018 ambient light and proximity sensor.

Addressed comments from reviews by Jonathan Cameron and Joe Perches
  * Removed some excess dbg prints that only printed function name
  * Renamed some properties to make them more descriptive
  * Added a property to list available adc resolutions
  * Defined arrays for resolutions/ranges as static const
  * Change loops initialization to memset for extensibility.
    * used sizeof() instead of ARRAY_SIZE() to be safer
  * Added a property to list available adc ranges
  * Fixed warnings and property names.
Signed-off-by: Rhyland Klein <rklein@nvidia.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/iio/Documentation/sysfs-bus-iio-light

+
+What:		/sys/bus/iio/devices/device[n]/range
+KernelVersion:	2.6.37
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Hardware dependent ADC Full Scale Range used for some ambient
+		light sensors in calculating lux.
+
+What:		/sys/bus/iio/devices/device[n]/range_available
+KernelVersion:	2.6.37
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Hardware dependent supported vales for ADC Full Scale Range.
+
+What:		/sys/bus/iio/devices/device[n]/adc_resolution
+KernelVersion:	2.6.37
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Hardware dependent ADC resolution of the ambient light sensor
+		used in calculating the lux.
+
+What:		/sys/bus/iio/devices/device[n]/adc_resolution_available
+KernelVersion:	2.6.37
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Hardware dependent list of possible values supported for the
+		adc_resolution of the given sensor.
+
+What:		/sys/bus/iio/devices/device[n]/illuminance0[_input|_raw]
+KernelVersion:	2.6.35
+Contact:	linux-iio@vger.kernel.org
+Description:
+		This should return the calculated lux from the light sensor. If
+		it comes back in SI units, it should also include _input else it
+		should include _raw to signify it is not in SI units.
+
+What:		/sys/.../device[n]/proximity_on_chip_ambient_infrared_supression
+KernelVersion:	2.6.37
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Hardware dependent mode for an ALS device to calculate the value
+		in proximity mode. When this is enabled, then the device should
+		use a infrared sensor reading to remove infrared noise from the
+		proximity reading. If this is not enabled, the driver can still
+		do this calculation manually by reading the infrared sensor
+		value and doing the negation in sw.
+
+What:		/sys/bus/iio/devices/device[n]/proximity[_input|_raw]
+KernelVersion:	2.6.37
+Contact:	linux-iio@vger.kernel.org
+Description:
+		This property is supported by proximity sensors and should be
+		used to return the value of a reading by the sensor. If this
+		value is returned in SI units, it should also include _input
+		but if it is not, then it should include _raw.
+
+What:		/sys/bus/iio/devices/device[n]/intensity_infrared[_input|_raw]
+KernelVersion:	2.6.37
+Contact:	linux-iio@vger.kernel.org
+Description:
+		This property is supported by sensors that have an infrared
+		sensing mode. This value should be the output from a reading
+		and if expressed in SI units, should include _input. If this
+		value is not in SI units, then it should include _raw.

drivers/staging/iio/light/Kconfig

@@ -12,3 +12,15 @@ config SENSORS_TSL2563
 
 	 This driver can also be built as a module.  If so, the module
 	 will be called tsl2563.
+
+config SENSORS_ISL29018
+        tristate "ISL 29018 light and proximity sensor"
+        depends on I2C
+        default n
+        help
+         If you say yes here you get support for ambient light sensing and
+         proximity infrared sensing from Intersil ISL29018.
+         This driver will provide the measurements of ambient light intensity
+         in lux, proximity infrared sensing and normal infrared sensing.
+         Data from sensor is accessible via sysfs.
+

drivers/staging/iio/light/Makefile

@@ -3,3 +3,4 @@
 #
 
 obj-$(CONFIG_SENSORS_TSL2563)	+= tsl2563.o
+obj-$(CONFIG_SENSORS_ISL29018)	+= isl29018.o