apds990x.rst (3655B)
1.. SPDX-License-Identifier: GPL-2.0 2 3====================== 4Kernel driver apds990x 5====================== 6 7Supported chips: 8Avago APDS990X 9 10Data sheet: 11Not freely available 12 13Author: 14Samu Onkalo <samu.p.onkalo@nokia.com> 15 16Description 17----------- 18 19APDS990x is a combined ambient light and proximity sensor. ALS and proximity 20functionality are highly connected. ALS measurement path must be running 21while the proximity functionality is enabled. 22 23ALS produces raw measurement values for two channels: Clear channel 24(infrared + visible light) and IR only. However, threshold comparisons happen 25using clear channel only. Lux value and the threshold level on the HW 26might vary quite much depending the spectrum of the light source. 27 28Driver makes necessary conversions to both directions so that user handles 29only lux values. Lux value is calculated using information from the both 30channels. HW threshold level is calculated from the given lux value to match 31with current type of the lightning. Sometimes inaccuracy of the estimations 32lead to false interrupt, but that doesn't harm. 33 34ALS contains 4 different gain steps. Driver automatically 35selects suitable gain step. After each measurement, reliability of the results 36is estimated and new measurement is triggered if necessary. 37 38Platform data can provide tuned values to the conversion formulas if 39values are known. Otherwise plain sensor default values are used. 40 41Proximity side is little bit simpler. There is no need for complex conversions. 42It produces directly usable values. 43 44Driver controls chip operational state using pm_runtime framework. 45Voltage regulators are controlled based on chip operational state. 46 47SYSFS 48----- 49 50 51chip_id 52 RO - shows detected chip type and version 53 54power_state 55 RW - enable / disable chip. Uses counting logic 56 57 1 enables the chip 58 0 disables the chip 59lux0_input 60 RO - measured lux value 61 62 sysfs_notify called when threshold interrupt occurs 63 64lux0_sensor_range 65 RO - lux0_input max value. 66 67 Actually never reaches since sensor tends 68 to saturate much before that. Real max value varies depending 69 on the light spectrum etc. 70 71lux0_rate 72 RW - measurement rate in Hz 73 74lux0_rate_avail 75 RO - supported measurement rates 76 77lux0_calibscale 78 RW - calibration value. 79 80 Set to neutral value by default. 81 Output results are multiplied with calibscale / calibscale_default 82 value. 83 84lux0_calibscale_default 85 RO - neutral calibration value 86 87lux0_thresh_above_value 88 RW - HI level threshold value. 89 90 All results above the value 91 trigs an interrupt. 65535 (i.e. sensor_range) disables the above 92 interrupt. 93 94lux0_thresh_below_value 95 RW - LO level threshold value. 96 97 All results below the value 98 trigs an interrupt. 0 disables the below interrupt. 99 100prox0_raw 101 RO - measured proximity value 102 103 sysfs_notify called when threshold interrupt occurs 104 105prox0_sensor_range 106 RO - prox0_raw max value (1023) 107 108prox0_raw_en 109 RW - enable / disable proximity - uses counting logic 110 111 - 1 enables the proximity 112 - 0 disables the proximity 113 114prox0_reporting_mode 115 RW - trigger / periodic. 116 117 In "trigger" mode the driver tells two possible 118 values: 0 or prox0_sensor_range value. 0 means no proximity, 119 1023 means proximity. This causes minimal number of interrupts. 120 In "periodic" mode the driver reports all values above 121 prox0_thresh_above. This causes more interrupts, but it can give 122 _rough_ estimate about the distance. 123 124prox0_reporting_mode_avail 125 RO - accepted values to prox0_reporting_mode (trigger, periodic) 126 127prox0_thresh_above_value 128 RW - threshold level which trigs proximity events.