Add initial version

This version is semi-tuned to give reasonable brightness.

brightness.sh

@@ -0,0 +1,89 @@
+#!/bin/bash
+
+max=$(cat /sys/class/backlight/intel_backlight/max_brightness)
+
+sensitivity=$((max/90))
+
+treshold=$((max/4))
+
+panOut=$((sensitivity/4))
+
+min=$((max/10))
+
+delay=2
+
+minSensor=404334
+
+
+while [ 1 ]
+do
+        updated=1
+        while [ $updated -gt 0 ]
+        do
+                updated=0
+                backlight=$(cat /sys/class/backlight/intel_backlight/brightness)
+                sensor=$(cat /sys/bus/iio/devices/iio:device0/in_illuminance_raw)
+		# Scale the sensor a bit
+		sensor=$((sensor/10))
+		sensor=$((5*sensor))
+		target=$backlight
+
+		echo Current backlight: $backlight
+		echo Max backlight: $max
+		echo Sensitivity is: $sensitivity
+		echo Threshold is: $treshold
+		echo panOut is: $panOut
+		echo min is: $min
+		echo Current sensor reading: $sensor
+		echo Target is: $backlight
+		
+                if [ $sensor -lt $treshold ]
+                then
+		    echo Sensor was less than backlight
+                    sensor=$(((sensor+panOut)+min))
+		    echo New sensor: $sensor
+                fi
+
+
+
+                if [ $sensor -gt $((backlight+sensitivity)) ]
+                then
+		    echo Sensor was greater than backlight+sensitivity
+                    updated=1
+                    target=$((target+(sensitivity/2)))
+		    echo New target: $target
+                fi
+
+
+                if [ $sensor -lt $((backlight-sensitivity)) ]
+                then
+		    echo Sensor was less than backlight-sensitivity
+                    updated=1
+                    target=$((target-(sensitivity/2)))
+		    echo New target: $target
+                fi
+
+
+                if [ $target -gt $max ]
+                then
+		    echo Target was greater than max brightness
+                    target=$max
+		    echo New target: $target		    
+                fi
+
+                if [ $target -lt 1 ]
+                then
+		    echo Target was less than 1
+                    target=$min
+		    echo New target: $target
+                fi
+
+                if [ $updated -gt 0 ]
+                then
+                        echo $target > /sys/class/backlight/intel_backlight/brightness
+                fi
+
+        done
+	echo Sleeping
+        sleep $delay
+done