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Documentation / misc-devices / bh1770glc.txt




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

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
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