Documentation/misc-devices/bh1770glc.txt

   1 Kernel driver bh1770glc
   2 =======================
   3
   4 Supported chips:
   5 ROHM BH1770GLC
   6 OSRAM SFH7770
   7
   8 Data sheet:
   9 Not freely available
  10
  11 Author:
  12 Samu Onkalo <samu.p.onkalo@nokia.com>
  13
  14 Description
  15 -----------
  16 BH1770GLC and SFH7770 are combined ambient light and proximity sensors.
  17 ALS and proximity parts operates on their own, but they shares common I2C
  18 interface and interrupt logic. In principle they can run on their own,
  19 but ALS side results are used to estimate reliability of the proximity sensor.
  20
  21 ALS produces 16 bit lux values. The chip contains interrupt logic to produce
  22 low and high threshold interrupts.
  23
  24 Proximity part contains IR-led driver up to 3 IR leds. The chip measures
  25 amount of reflected IR light and produces proximity result. Resolution is
  26 8 bit. Driver supports only one channel. Driver uses ALS results to estimate
  27 reliability of the proximity results. Thus ALS is always running while
  28 proximity detection is needed.
  29
  30 Driver uses threshold interrupts to avoid need for polling the values.
  31 Proximity low interrupt doesn't exists in the chip. This is simulated
  32 by using a delayed work. As long as there is proximity threshold above
  33 interrupts the delayed work is pushed forward. So, when proximity level goes
  34 below the threshold value, there is no interrupt and the delayed work will
  35 finally run. This is handled as no proximity indication.
  36
  37 Chip state is controlled via runtime pm framework when enabled in config.
  38
  39 Calibscale factor is used to hide differences between the chips. By default
  40 value set to neutral state meaning factor of 1.00. To get proper values,
  41 calibrated source of light is needed as a reference. Calibscale factor is set
  42 so that measurement produces about the expected lux value.
  43
  44 SYSFS
  45 -----
  46
  47 chip_id
  48         RO - shows detected chip type and version
  49
  50 power_state
  51         RW - enable / disable chip. Uses counting logic
  52              1 enables the chip
  53              0 disables the chip
  54
  55 lux0_input
  56         RO - measured lux value
  57              sysfs_notify called when threshold interrupt occurs
  58
  59 lux0_sensor_range
  60         RO - lux0_input max value
  61
  62 lux0_rate
  63         RW - measurement rate in Hz
  64
  65 lux0_rate_avail
  66         RO - supported measurement rates
  67
  68 lux0_thresh_above_value
  69         RW - HI level threshold value. All results above the value
  70              trigs an interrupt. 65535 (i.e. sensor_range) disables the above
  71              interrupt.
  72
  73 lux0_thresh_below_value
  74         RW - LO level threshold value. All results below the value
  75              trigs an interrupt. 0 disables the below interrupt.
  76
  77 lux0_calibscale
  78         RW - calibration value. Set to neutral value by default.
  79              Output results are multiplied with calibscale / calibscale_default
  80              value.
  81
  82 lux0_calibscale_default
  83         RO - neutral calibration value
  84
  85 prox0_raw
  86         RO - measured proximity value
  87              sysfs_notify called when threshold interrupt occurs
  88
  89 prox0_sensor_range
  90         RO - prox0_raw max value
  91
  92 prox0_raw_en
  93         RW - enable / disable proximity - uses counting logic
  94              1 enables the proximity
  95              0 disables the proximity
  96
  97 prox0_thresh_above_count
  98         RW - number of proximity interrupts needed before triggering the event
  99
 100 prox0_rate_above
 101         RW - Measurement rate (in Hz) when the level is above threshold
 102              i.e. when proximity on has been reported.
 103
 104 prox0_rate_below
 105         RW - Measurement rate (in Hz) when the level is below threshold
 106              i.e. when proximity off has been reported.
 107
 108 prox0_rate_avail
 109         RO - Supported proximity measurement rates in Hz
 110
 111 prox0_thresh_above0_value
 112         RW - threshold level which trigs proximity events.
 113              Filtered by persistence filter (prox0_thresh_above_count)
 114
 115 prox0_thresh_above1_value
 116         RW - threshold level which trigs event immediately