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Documentation / misc-devices / apds990x.txt




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Based on kernel version 3.9. Page generated on 2013-05-02 23:10 EST.

1	Kernel driver apds990x
2	======================
3	
4	Supported chips:
5	Avago APDS990X
6	
7	Data sheet:
8	Not freely available
9	
10	Author:
11	Samu Onkalo <samu.p.onkalo@nokia.com>
12	
13	Description
14	-----------
15	
16	APDS990x is a combined ambient light and proximity sensor. ALS and proximity
17	functionality are highly connected. ALS measurement path must be running
18	while the proximity functionality is enabled.
19	
20	ALS produces raw measurement values for two channels: Clear channel
21	(infrared + visible light) and IR only. However, threshold comparisons happen
22	using clear channel only. Lux value and the threshold level on the HW
23	might vary quite much depending the spectrum of the light source.
24	
25	Driver makes necessary conversions to both directions so that user handles
26	only lux values. Lux value is calculated using information from the both
27	channels. HW threshold level is calculated from the given lux value to match
28	with current type of the lightning. Sometimes inaccuracy of the estimations
29	lead to false interrupt, but that doesn't harm.
30	
31	ALS contains 4 different gain steps. Driver automatically
32	selects suitable gain step. After each measurement, reliability of the results
33	is estimated and new measurement is trigged if necessary.
34	
35	Platform data can provide tuned values to the conversion formulas if
36	values are known. Otherwise plain sensor default values are used.
37	
38	Proximity side is little bit simpler. There is no need for complex conversions.
39	It produces directly usable values.
40	
41	Driver controls chip operational state using pm_runtime framework.
42	Voltage regulators are controlled based on chip operational state.
43	
44	SYSFS
45	-----
46	
47	
48	chip_id
49		RO - shows detected chip type and version
50	
51	power_state
52		RW - enable / disable chip. Uses counting logic
53		     1 enables the chip
54		     0 disables the chip
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. Actually never reaches since sensor tends
61		     to saturate much before that. Real max value varies depending
62		     on the light spectrum etc.
63	
64	lux0_rate
65		RW - measurement rate in Hz
66	
67	lux0_rate_avail
68		RO - supported measurement rates
69	
70	lux0_calibscale
71		RW - calibration value. Set to neutral value by default.
72		     Output results are multiplied with calibscale / calibscale_default
73		     value.
74	
75	lux0_calibscale_default
76		RO - neutral calibration value
77	
78	lux0_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	
83	lux0_thresh_below_value
84		RW - LO level threshold value. All results below the value
85		     trigs an interrupt. 0 disables the below interrupt.
86	
87	prox0_raw
88		RO - measured proximity value
89		     sysfs_notify called when threshold interrupt occurs
90	
91	prox0_sensor_range
92		RO - prox0_raw max value (1023)
93	
94	prox0_raw_en
95		RW - enable / disable proximity - uses counting logic
96		     1 enables the proximity
97		     0 disables the proximity
98	
99	prox0_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	
107	prox0_reporting_mode_avail
108		RO - accepted values to prox0_reporting_mode (trigger, periodic)
109	
110	prox0_thresh_above_value
111		RW - threshold level which trigs proximity events.
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