1 .. SPDX-License-Identifier: GPL-2.0 2 3 ======================= 4 Kernel driver bh1770glc 5 ======================= 6 7 Supported chips: 8 9 - ROHM BH1770GLC 10 - OSRAM SFH7770 11 12 Data sheet: 13 Not freely available 14 15 Author: 16 Samu Onkalo <samu.p.onkalo@nokia.com> 17 18 Description 19 ----------- 20 BH1770GLC and SFH7770 are combined ambient light and proximity sensors. 21 ALS and proximity parts operates on their own, but they shares common I2C 22 interface and interrupt logic. In principle they can run on their own, 23 but ALS side results are used to estimate reliability of the proximity sensor. 24 25 ALS produces 16 bit lux values. The chip contains interrupt logic to produce 26 low and high threshold interrupts. 27 28 Proximity part contains IR-led driver up to 3 IR leds. The chip measures 29 amount of reflected IR light and produces proximity result. Resolution is 30 8 bit. Driver supports only one channel. Driver uses ALS results to estimate 31 reliability of the proximity results. Thus ALS is always running while 32 proximity detection is needed. 33 34 Driver uses threshold interrupts to avoid need for polling the values. 35 Proximity low interrupt doesn't exists in the chip. This is simulated 36 by using a delayed work. As long as there is proximity threshold above 37 interrupts the delayed work is pushed forward. So, when proximity level goes 38 below the threshold value, there is no interrupt and the delayed work will 39 finally run. This is handled as no proximity indication. 40 41 Chip state is controlled via runtime pm framework when enabled in config. 42 43 Calibscale factor is used to hide differences between the chips. By default 44 value set to neutral state meaning factor of 1.00. To get proper values, 45 calibrated source of light is needed as a reference. Calibscale factor is set 46 so that measurement produces about the expected lux value. 47 48 SYSFS 49 ----- 50 51 chip_id 52 RO - shows detected chip type and version 53 54 power_state 55 RW - enable / disable chip 56 57 Uses counting logic 58 59 - 1 enables the chip 60 - 0 disables the chip 61 62 lux0_input 63 RO - measured lux value 64 65 sysfs_notify called when threshold interrupt occurs 66 67 lux0_sensor_range 68 RO - lux0_input max value 69 70 lux0_rate 71 RW - measurement rate in Hz 72 73 lux0_rate_avail 74 RO - supported measurement rates 75 76 lux0_thresh_above_value 77 RW - HI level threshold value 78 79 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 85 86 All results below the value 87 trigs an interrupt. 0 disables the below interrupt. 88 89 lux0_calibscale 90 RW - calibration value 91 92 Set to neutral value by default. 93 Output results are multiplied with calibscale / calibscale_default 94 value. 95 96 lux0_calibscale_default 97 RO - neutral calibration value 98 99 prox0_raw 100 RO - measured proximity value 101 102 sysfs_notify called when threshold interrupt occurs 103 104 prox0_sensor_range 105 RO - prox0_raw max value 106 107 prox0_raw_en 108 RW - enable / disable proximity 109 110 Uses counting logic 111 112 - 1 enables the proximity 113 - 0 disables the proximity 114 115 prox0_thresh_above_count 116 RW - number of proximity interrupts needed before triggering the event 117 118 prox0_rate_above 119 RW - Measurement rate (in Hz) when the level is above threshold 120 i.e. when proximity on has been reported. 121 122 prox0_rate_below 123 RW - Measurement rate (in Hz) when the level is below threshold 124 i.e. when proximity off has been reported. 125 126 prox0_rate_avail 127 RO - Supported proximity measurement rates in Hz 128 129 prox0_thresh_above0_value 130 RW - threshold level which trigs proximity events. 131 132 Filtered by persistence filter (prox0_thresh_above_count) 133 134 prox0_thresh_above1_value 135 RW - threshold level which trigs event immediately
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