bh1770glc.rst (3685B)
1.. SPDX-License-Identifier: GPL-2.0 2 3======================= 4Kernel driver bh1770glc 5======================= 6 7Supported chips: 8 9- ROHM BH1770GLC 10- OSRAM SFH7770 11 12Data sheet: 13Not freely available 14 15Author: 16Samu Onkalo <samu.p.onkalo@nokia.com> 17 18Description 19----------- 20BH1770GLC and SFH7770 are combined ambient light and proximity sensors. 21ALS and proximity parts operates on their own, but they shares common I2C 22interface and interrupt logic. In principle they can run on their own, 23but ALS side results are used to estimate reliability of the proximity sensor. 24 25ALS produces 16 bit lux values. The chip contains interrupt logic to produce 26low and high threshold interrupts. 27 28Proximity part contains IR-led driver up to 3 IR leds. The chip measures 29amount of reflected IR light and produces proximity result. Resolution is 308 bit. Driver supports only one channel. Driver uses ALS results to estimate 31reliability of the proximity results. Thus ALS is always running while 32proximity detection is needed. 33 34Driver uses threshold interrupts to avoid need for polling the values. 35Proximity low interrupt doesn't exists in the chip. This is simulated 36by using a delayed work. As long as there is proximity threshold above 37interrupts the delayed work is pushed forward. So, when proximity level goes 38below the threshold value, there is no interrupt and the delayed work will 39finally run. This is handled as no proximity indication. 40 41Chip state is controlled via runtime pm framework when enabled in config. 42 43Calibscale factor is used to hide differences between the chips. By default 44value set to neutral state meaning factor of 1.00. To get proper values, 45calibrated source of light is needed as a reference. Calibscale factor is set 46so that measurement produces about the expected lux value. 47 48SYSFS 49----- 50 51chip_id 52 RO - shows detected chip type and version 53 54power_state 55 RW - enable / disable chip 56 57 Uses counting logic 58 59 - 1 enables the chip 60 - 0 disables the chip 61 62lux0_input 63 RO - measured lux value 64 65 sysfs_notify called when threshold interrupt occurs 66 67lux0_sensor_range 68 RO - lux0_input max value 69 70lux0_rate 71 RW - measurement rate in Hz 72 73lux0_rate_avail 74 RO - supported measurement rates 75 76lux0_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 83lux0_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 89lux0_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 96lux0_calibscale_default 97 RO - neutral calibration value 98 99prox0_raw 100 RO - measured proximity value 101 102 sysfs_notify called when threshold interrupt occurs 103 104prox0_sensor_range 105 RO - prox0_raw max value 106 107prox0_raw_en 108 RW - enable / disable proximity 109 110 Uses counting logic 111 112 - 1 enables the proximity 113 - 0 disables the proximity 114 115prox0_thresh_above_count 116 RW - number of proximity interrupts needed before triggering the event 117 118prox0_rate_above 119 RW - Measurement rate (in Hz) when the level is above threshold 120 i.e. when proximity on has been reported. 121 122prox0_rate_below 123 RW - Measurement rate (in Hz) when the level is below threshold 124 i.e. when proximity off has been reported. 125 126prox0_rate_avail 127 RO - Supported proximity measurement rates in Hz 128 129prox0_thresh_above0_value 130 RW - threshold level which trigs proximity events. 131 132 Filtered by persistence filter (prox0_thresh_above_count) 133 134prox0_thresh_above1_value 135 RW - threshold level which trigs event immediately