| .. SPDX-License-Identifier: GPL-2.0 | |
| ======================= | |
| Kernel driver bh1770glc | |
| ======================= | |
| Supported chips: | |
| - ROHM BH1770GLC | |
| - OSRAM SFH7770 | |
| Data sheet: | |
| Not freely available | |
| Author: | |
| Samu Onkalo <samu.p.onkalo@nokia.com> | |
| Description | |
| ----------- | |
| BH1770GLC and SFH7770 are combined ambient light and proximity sensors. | |
| ALS and proximity parts operates on their own, but they shares common I2C | |
| interface and interrupt logic. In principle they can run on their own, | |
| but ALS side results are used to estimate reliability of the proximity sensor. | |
| ALS produces 16 bit lux values. The chip contains interrupt logic to produce | |
| low and high threshold interrupts. | |
| Proximity part contains IR-led driver up to 3 IR leds. The chip measures | |
| amount of reflected IR light and produces proximity result. Resolution is | |
| 8 bit. Driver supports only one channel. Driver uses ALS results to estimate | |
| reliability of the proximity results. Thus ALS is always running while | |
| proximity detection is needed. | |
| Driver uses threshold interrupts to avoid need for polling the values. | |
| Proximity low interrupt doesn't exists in the chip. This is simulated | |
| by using a delayed work. As long as there is proximity threshold above | |
| interrupts the delayed work is pushed forward. So, when proximity level goes | |
| below the threshold value, there is no interrupt and the delayed work will | |
| finally run. This is handled as no proximity indication. | |
| Chip state is controlled via runtime pm framework when enabled in config. | |
| Calibscale factor is used to hide differences between the chips. By default | |
| value set to neutral state meaning factor of 1.00. To get proper values, | |
| calibrated source of light is needed as a reference. Calibscale factor is set | |
| so that measurement produces about the expected lux value. | |
| SYSFS | |
| ----- | |
| chip_id | |
| RO - shows detected chip type and version | |
| power_state | |
| RW - enable / disable chip | |
| Uses counting logic | |
| - 1 enables the chip | |
| - 0 disables the chip | |
| lux0_input | |
| RO - measured lux value | |
| sysfs_notify called when threshold interrupt occurs | |
| lux0_sensor_range | |
| RO - lux0_input max value | |
| lux0_rate | |
| RW - measurement rate in Hz | |
| lux0_rate_avail | |
| RO - supported measurement rates | |
| lux0_thresh_above_value | |
| RW - HI level threshold value | |
| All results above the value | |
| trigs an interrupt. 65535 (i.e. sensor_range) disables the above | |
| interrupt. | |
| lux0_thresh_below_value | |
| RW - LO level threshold value | |
| All results below the value | |
| trigs an interrupt. 0 disables the below interrupt. | |
| lux0_calibscale | |
| RW - calibration value | |
| Set to neutral value by default. | |
| Output results are multiplied with calibscale / calibscale_default | |
| value. | |
| lux0_calibscale_default | |
| RO - neutral calibration value | |
| prox0_raw | |
| RO - measured proximity value | |
| sysfs_notify called when threshold interrupt occurs | |
| prox0_sensor_range | |
| RO - prox0_raw max value | |
| prox0_raw_en | |
| RW - enable / disable proximity | |
| Uses counting logic | |
| - 1 enables the proximity | |
| - 0 disables the proximity | |
| prox0_thresh_above_count | |
| RW - number of proximity interrupts needed before triggering the event | |
| prox0_rate_above | |
| RW - Measurement rate (in Hz) when the level is above threshold | |
| i.e. when proximity on has been reported. | |
| prox0_rate_below | |
| RW - Measurement rate (in Hz) when the level is below threshold | |
| i.e. when proximity off has been reported. | |
| prox0_rate_avail | |
| RO - Supported proximity measurement rates in Hz | |
| prox0_thresh_above0_value | |
| RW - threshold level which trigs proximity events. | |
| Filtered by persistence filter (prox0_thresh_above_count) | |
| prox0_thresh_above1_value | |
| RW - threshold level which trigs event immediately |