diff options
Diffstat (limited to 'Documentation/misc-devices/bh1770glc.rst')
| -rw-r--r-- | Documentation/misc-devices/bh1770glc.rst | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/Documentation/misc-devices/bh1770glc.rst b/Documentation/misc-devices/bh1770glc.rst new file mode 100644 index 000000000000..ea5ca58bb958 --- /dev/null +++ b/Documentation/misc-devices/bh1770glc.rst @@ -0,0 +1,135 @@ +.. 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 |