Merge pull request #2 from ianalis/master

Add automatic adjustment of backlight

PKGBUILD

@@ -34,6 +34,8 @@ package() {
   cp -r wacom "$pkgdir/opt/$_gitname"
   ## Tablet mode
   cp -r tablet "$pkgdir/opt/$_gitname"
+  ## Backlight script
+  cp -r backlight "$pkgdir/opt/$_gitname"
 
   # ThinkPad Yoga Systemd Services
   mkdir -p "$pkgdir/usr/lib/systemd/system/"

backlight/thinkpad-backlight.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python
+
+import glob
+import os.path
+import sys
+import math
+import time
+
+# min value of light sensor for automatic adjustment of backlight
+LS_LOW = 1
+# max value of light sensor for automatic adjustment of backlight
+LS_HIGH = 500
+# scale factor of backlight value exponential function
+SCALE = 89
+# exponent scaling factor of backlight exponential function
+EXP = 0.004615
+# minimum change in sensor intensity before backlight intensity is changed
+TOL = 5
+# time in seconds between successive sensor reads
+SLEEP_TIME = 1
+
+sensor_dir = None
+for f in glob.glob('/sys/bus/iio/devices/iio:device*/name'):
+    if 'als' in open(f).read():
+        sensor_dir = os.path.dirname(f)
+if not sensor_dir:
+    print('sensor not found')
+    sys.exit(-1)
+
+abs_max_bl = int(open('/sys/class/backlight/intel_backlight/'
+                      'max_brightness').read())
+min_bl = max(int(SCALE * math.exp(EXP * LS_LOW)), 0)
+max_bl = min(int(SCALE * math.exp(EXP * LS_HIGH)), abs_max_bl)
+
+old_bl_val = -100
+while 1:
+    with open(os.path.join(sensor_dir, 'in_intensity_both_raw')) as ls_file:
+        ls_val = int(ls_file.readline().strip())
+
+    if ls_val < LS_LOW:
+        bl_val = min_bl
+    elif LS_LOW <= ls_val < LS_HIGH:
+        bl_val = int(SCALE * math.exp(EXP * ls_val))
+        bl_val = max(bl_val, min_bl)
+        bl_val = min(bl_val, max_bl)
+    else:
+        bl_val = max_bl
+    
+    if abs(bl_val - old_bl_val) >= TOL:
+        with open('/sys/class/backlight/intel_backlight/brightness', 'w') as bl_file:
+            bl_file.write('%s\n' % (bl_val))
+        print min_bl, max_bl, ls_val, bl_val
+
+    old_bl_val = bl_val
+    time.sleep(SLEEP_TIME)