1Kernel driver bh1770glc
2=======================
3
4Supported chips:
5ROHM BH1770GLC
6OSRAM SFH7770
7
8Data sheet:
9Not freely available
10
11Author:
12Samu Onkalo <samu.p.onkalo@nokia.com>
13
14Description
15-----------
16BH1770GLC and SFH7770 are combined ambient light and proximity sensors.
17ALS and proximity parts operates on their own, but they shares common I2C
18interface and interrupt logic. In principle they can run on their own,
19but ALS side results are used to estimate reliability of the proximity sensor.
20
21ALS produces 16 bit lux values. The chip contains interrupt logic to produce
22low and high threshold interrupts.
23
24Proximity part contains IR-led driver up to 3 IR leds. The chip measures
25amount of reflected IR light and produces proximity result. Resolution is
268 bit. Driver supports only one channel. Driver uses ALS results to estimate
27reliability of the proximity results. Thus ALS is always running while
28proximity detection is needed.
29
30Driver uses threshold interrupts to avoid need for polling the values.
31Proximity low interrupt doesn't exists in the chip. This is simulated
32by using a delayed work. As long as there is proximity threshold above
33interrupts the delayed work is pushed forward. So, when proximity level goes
34below the threshold value, there is no interrupt and the delayed work will
35finally run. This is handled as no proximity indication.
36
37Chip state is controlled via runtime pm framework when enabled in config.
38
39Calibscale factor is used to hide differences between the chips. By default
40value set to neutral state meaning factor of 1.00. To get proper values,
41calibrated source of light is needed as a reference. Calibscale factor is set
42so that measurement produces about the expected lux value.
43
44SYSFS
45-----
46
47chip_id
48	RO - shows detected chip type and version
49
50power_state
51	RW - enable / disable chip. Uses counting logic
52	     1 enables the chip
53	     0 disables the chip
54
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
61
62lux0_rate
63	RW - measurement rate in Hz
64
65lux0_rate_avail
66	RO - supported measurement rates
67
68lux0_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
73lux0_thresh_below_value
74	RW - LO level threshold value. All results below the value
75	     trigs an interrupt. 0 disables the below interrupt.
76
77lux0_calibscale
78	RW - calibration value. Set to neutral value by default.
79	     Output results are multiplied with calibscale / calibscale_default
80	     value.
81
82lux0_calibscale_default
83	RO - neutral calibration value
84
85prox0_raw
86	RO - measured proximity value
87	     sysfs_notify called when threshold interrupt occurs
88
89prox0_sensor_range
90	RO - prox0_raw max value
91
92prox0_raw_en
93	RW - enable / disable proximity - uses counting logic
94	     1 enables the proximity
95	     0 disables the proximity
96
97prox0_thresh_above_count
98	RW - number of proximity interrupts needed before triggering the event
99
100prox0_rate_above
101	RW - Measurement rate (in Hz) when the level is above threshold
102	     i.e. when proximity on has been reported.
103
104prox0_rate_below
105	RW - Measurement rate (in Hz) when the level is below threshold
106	     i.e. when proximity off has been reported.
107
108prox0_rate_avail
109	RO - Supported proximity measurement rates in Hz
110
111prox0_thresh_above0_value
112	RW - threshold level which trigs proximity events.
113	     Filtered by persistence filter (prox0_thresh_above_count)
114
115prox0_thresh_above1_value
116	RW - threshold level which trigs event immediately
117