1Kernel driver apds990x
  2======================
  3
  4Supported chips:
  5Avago APDS990X
  6
  7Data sheet:
  8Not freely available
  9
 10Author:
 11Samu Onkalo <samu.p.onkalo@nokia.com>
 12
 13Description
 14-----------
 15
 16APDS990x is a combined ambient light and proximity sensor. ALS and proximity
 17functionality are highly connected. ALS measurement path must be running
 18while the proximity functionality is enabled.
 19
 20ALS produces raw measurement values for two channels: Clear channel
 21(infrared + visible light) and IR only. However, threshold comparisons happen
 22using clear channel only. Lux value and the threshold level on the HW
 23might vary quite much depending the spectrum of the light source.
 24
 25Driver makes necessary conversions to both directions so that user handles
 26only lux values. Lux value is calculated using information from the both
 27channels. HW threshold level is calculated from the given lux value to match
 28with current type of the lightning. Sometimes inaccuracy of the estimations
 29lead to false interrupt, but that doesn't harm.
 30
 31ALS contains 4 different gain steps. Driver automatically
 32selects suitable gain step. After each measurement, reliability of the results
 33is estimated and new measurement is triggered if necessary.
 34
 35Platform data can provide tuned values to the conversion formulas if
 36values are known. Otherwise plain sensor default values are used.
 37
 38Proximity side is little bit simpler. There is no need for complex conversions.
 39It produces directly usable values.
 40
 41Driver controls chip operational state using pm_runtime framework.
 42Voltage regulators are controlled based on chip operational state.
 43
 44SYSFS
 45-----
 46
 47
 48chip_id
 49	RO - shows detected chip type and version
 50
 51power_state
 52	RW - enable / disable chip. Uses counting logic
 53	     1 enables the chip
 54	     0 disables the chip
 55lux0_input
 56	RO - measured lux value
 57	     sysfs_notify called when threshold interrupt occurs
 58
 59lux0_sensor_range
 60	RO - lux0_input max value. Actually never reaches since sensor tends
 61	     to saturate much before that. Real max value varies depending
 62	     on the light spectrum etc.
 63
 64lux0_rate
 65	RW - measurement rate in Hz
 66
 67lux0_rate_avail
 68	RO - supported measurement rates
 69
 70lux0_calibscale
 71	RW - calibration value. Set to neutral value by default.
 72	     Output results are multiplied with calibscale / calibscale_default
 73	     value.
 74
 75lux0_calibscale_default
 76	RO - neutral calibration value
 77
 78lux0_thresh_above_value
 79	RW - HI level threshold value. All results above the value
 80	     trigs an interrupt. 65535 (i.e. sensor_range) disables the above
 81	     interrupt.
 82
 83lux0_thresh_below_value
 84	RW - LO level threshold value. All results below the value
 85	     trigs an interrupt. 0 disables the below interrupt.
 86
 87prox0_raw
 88	RO - measured proximity value
 89	     sysfs_notify called when threshold interrupt occurs
 90
 91prox0_sensor_range
 92	RO - prox0_raw max value (1023)
 93
 94prox0_raw_en
 95	RW - enable / disable proximity - uses counting logic
 96	     1 enables the proximity
 97	     0 disables the proximity
 98
 99prox0_reporting_mode
100	RW - trigger / periodic. In "trigger" mode the driver tells two possible
101	     values: 0 or prox0_sensor_range value. 0 means no proximity,
102	     1023 means proximity. This causes minimal number of interrupts.
103	     In "periodic" mode the driver reports all values above
104	     prox0_thresh_above. This causes more interrupts, but it can give
105	     _rough_ estimate about the distance.
106
107prox0_reporting_mode_avail
108	RO - accepted values to prox0_reporting_mode (trigger, periodic)
109
110prox0_thresh_above_value
111	RW - threshold level which trigs proximity events.