1 .. SPDX-License-Identifier: GPL-2.0 2 3 ====================== 4 Kernel driver apds990x 5 ====================== 6 7 Supported chips: 8 Avago APDS990X 9 10 Data sheet: 11 Not freely available 12 13 Author: 14 Samu Onkalo <samu.p.onkalo@nokia.com> 15 16 Description 17 ----------- 18 19 APDS990x is a combined ambient light and proximity sensor. ALS and proximity 20 functionality are highly connected. ALS measurement path must be running 21 while the proximity functionality is enabled. 22 23 ALS produces raw measurement values for two channels: Clear channel 24 (infrared + visible light) and IR only. However, threshold comparisons happen 25 using clear channel only. Lux value and the threshold level on the HW 26 might vary quite much depending the spectrum of the light source. 27 28 Driver makes necessary conversions to both directions so that user handles 29 only lux values. Lux value is calculated using information from the both 30 channels. HW threshold level is calculated from the given lux value to match 31 with current type of the lightning. Sometimes inaccuracy of the estimations 32 lead to false interrupt, but that doesn't harm. 33 34 ALS contains 4 different gain steps. Driver automatically 35 selects suitable gain step. After each measurement, reliability of the results 36 is estimated and new measurement is triggered if necessary. 37 38 Platform data can provide tuned values to the conversion formulas if 39 values are known. Otherwise plain sensor default values are used. 40 41 Proximity side is little bit simpler. There is no need for complex conversions. 42 It produces directly usable values. 43 44 Driver controls chip operational state using pm_runtime framework. 45 Voltage regulators are controlled based on chip operational state. 46 47 SYSFS 48 ----- 49 50 51 chip_id 52 RO - shows detected chip type and version 53 54 power_state 55 RW - enable / disable chip. Uses counting logic 56 57 1 enables the chip 58 0 disables the chip 59 lux0_input 60 RO - measured lux value 61 62 sysfs_notify called when threshold interrupt occurs 63 64 lux0_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 71 lux0_rate 72 RW - measurement rate in Hz 73 74 lux0_rate_avail 75 RO - supported measurement rates 76 77 lux0_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 84 lux0_calibscale_default 85 RO - neutral calibration value 86 87 lux0_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 94 lux0_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. 99 100 prox0_raw 101 RO - measured proximity value 102 103 sysfs_notify called when threshold interrupt occurs 104 105 prox0_sensor_range 106 RO - prox0_raw max value (1023) 107 108 prox0_raw_en 109 RW - enable / disable proximity - uses counting logic 110 111 - 1 enables the proximity 112 - 0 disables the proximity 113 114 prox0_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. 123 124 prox0_reporting_mode_avail 125 RO - accepted values to prox0_reporting_mode (trigger, periodic) 126 127 prox0_thresh_above_value 128 RW - threshold level which trigs proximity events.
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.