Documentation/misc-devices/bh1770glc.rst
.. SPDX-License-Identifier: GPL-2.0
Supported chips:
Data sheet: Not freely available
Author: Samu Onkalo [email protected]
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.
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