Root/Documentation/misc-devices/apds990x.txt

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 trigged 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.
112

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