1.. SPDX-License-Identifier: GPL-2.0
2
3======================
4Kernel driver apds990x
5======================
6
7Supported chips:
8Avago APDS990X
9
10Data sheet:
11Not freely available
12
13Author:
14Samu Onkalo <samu.p.onkalo@nokia.com>
15
16Description
17-----------
18
19APDS990x is a combined ambient light and proximity sensor. ALS and proximity
20functionality are highly connected. ALS measurement path must be running
21while the proximity functionality is enabled.
22
23ALS produces raw measurement values for two channels: Clear channel
24(infrared + visible light) and IR only. However, threshold comparisons happen
25using clear channel only. Lux value and the threshold level on the HW
26might vary quite much depending the spectrum of the light source.
27
28Driver makes necessary conversions to both directions so that user handles
29only lux values. Lux value is calculated using information from the both
30channels. HW threshold level is calculated from the given lux value to match
31with current type of the lightning. Sometimes inaccuracy of the estimations
32lead to false interrupt, but that doesn't harm.
33
34ALS contains 4 different gain steps. Driver automatically
35selects suitable gain step. After each measurement, reliability of the results
36is estimated and new measurement is triggered if necessary.
37
38Platform data can provide tuned values to the conversion formulas if
39values are known. Otherwise plain sensor default values are used.
40
41Proximity side is little bit simpler. There is no need for complex conversions.
42It produces directly usable values.
43
44Driver controls chip operational state using pm_runtime framework.
45Voltage regulators are controlled based on chip operational state.
46
47SYSFS
48-----
49
50
51chip_id
52	RO - shows detected chip type and version
53
54power_state
55	RW - enable / disable chip. Uses counting logic
56
57	     1 enables the chip
58	     0 disables the chip
59lux0_input
60	RO - measured lux value
61
62	     sysfs_notify called when threshold interrupt occurs
63
64lux0_sensor_range
65	RO - lux0_input max value.
66
67	     Actually never reaches since sensor tends
68	     to saturate much before that. Real max value varies depending
69	     on the light spectrum etc.
70
71lux0_rate
72	RW - measurement rate in Hz
73
74lux0_rate_avail
75	RO - supported measurement rates
76
77lux0_calibscale
78	RW - calibration value.
79
80	     Set to neutral value by default.
81	     Output results are multiplied with calibscale / calibscale_default
82	     value.
83
84lux0_calibscale_default
85	RO - neutral calibration value
86
87lux0_thresh_above_value
88	RW - HI level threshold value.
89
90	     All results above the value
91	     trigs an interrupt. 65535 (i.e. sensor_range) disables the above
92	     interrupt.
93
94lux0_thresh_below_value
95	RW - LO level threshold value.
96
97	     All results below the value
98	     trigs an interrupt. 0 disables the below interrupt.
99
100prox0_raw
101	RO - measured proximity value
102
103	     sysfs_notify called when threshold interrupt occurs
104
105prox0_sensor_range
106	RO - prox0_raw max value (1023)
107
108prox0_raw_en
109	RW - enable / disable proximity - uses counting logic
110
111	     - 1 enables the proximity
112	     - 0 disables the proximity
113
114prox0_reporting_mode
115	RW - trigger / periodic.
116
117	     In "trigger" mode the driver tells two possible
118	     values: 0 or prox0_sensor_range value. 0 means no proximity,
119	     1023 means proximity. This causes minimal number of interrupts.
120	     In "periodic" mode the driver reports all values above
121	     prox0_thresh_above. This causes more interrupts, but it can give
122	     _rough_ estimate about the distance.
123
124prox0_reporting_mode_avail
125	RO - accepted values to prox0_reporting_mode (trigger, periodic)
126
127prox0_thresh_above_value
128	RW - threshold level which trigs proximity events.
129