mirror of
https://github.com/torvalds/linux.git
synced 2024-11-10 22:21:40 +00:00
Documentation: short descriptions for bh1770glc and apds990x drivers
Add short documentation for two ALS / proximity chip drivers. Signed-off-by: Samu Onkalo <samu.p.onkalo@nokia.com> Acked-by: Jonathan Cameron <jic23@cam.ac.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Samu Onkalo
Linus Torvalds
parent
92b1f84d46
commit
3f0f4a3f20
111
Documentation/misc-devices/apds990x.txt
Normal file
111
Documentation/misc-devices/apds990x.txt
Normal file
@ -0,0 +1,111 @@
|
||||
Kernel driver apds990x
|
||||
======================
|
||||
|
||||
Supported chips:
|
||||
Avago APDS990X
|
||||
|
||||
Data sheet:
|
||||
Not freely available
|
||||
|
||||
Author:
|
||||
Samu Onkalo <samu.p.onkalo@nokia.com>
|
||||
|
||||
Description
|
||||
-----------
|
||||
|
||||
APDS990x is a combined ambient light and proximity sensor. ALS and proximity
|
||||
functionality are highly connected. ALS measurement path must be running
|
||||
while the proximity functionality is enabled.
|
||||
|
||||
ALS produces raw measurement values for two channels: Clear channel
|
||||
(infrared + visible light) and IR only. However, threshold comparisons happen
|
||||
using clear channel only. Lux value and the threshold level on the HW
|
||||
might vary quite much depending the spectrum of the light source.
|
||||
|
||||
Driver makes necessary conversions to both directions so that user handles
|
||||
only lux values. Lux value is calculated using information from the both
|
||||
channels. HW threshold level is calculated from the given lux value to match
|
||||
with current type of the lightning. Sometimes inaccuracy of the estimations
|
||||
lead to false interrupt, but that doesn't harm.
|
||||
|
||||
ALS contains 4 different gain steps. Driver automatically
|
||||
selects suitable gain step. After each measurement, reliability of the results
|
||||
is estimated and new measurement is trigged if necessary.
|
||||
|
||||
Platform data can provide tuned values to the conversion formulas if
|
||||
values are known. Otherwise plain sensor default values are used.
|
||||
|
||||
Proximity side is little bit simpler. There is no need for complex conversions.
|
||||
It produces directly usable values.
|
||||
|
||||
Driver controls chip operational state using pm_runtime framework.
|
||||
Voltage regulators are controlled based on chip operational state.
|
||||
|
||||
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. Actually never reaches since sensor tends
|
||||
to saturate much before that. Real max value varies depending
|
||||
on the light spectrum etc.
|
||||
|
||||
lux0_rate
|
||||
RW - measurement rate in Hz
|
||||
|
||||
lux0_rate_avail
|
||||
RO - supported measurement rates
|
||||
|
||||
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
|
||||
|
||||
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.
|
||||
|
||||
prox0_raw
|
||||
RO - measured proximity value
|
||||
sysfs_notify called when threshold interrupt occurs
|
||||
|
||||
prox0_sensor_range
|
||||
RO - prox0_raw max value (1023)
|
||||
|
||||
prox0_raw_en
|
||||
RW - enable / disable proximity - uses counting logic
|
||||
1 enables the proximity
|
||||
0 disables the proximity
|
||||
|
||||
prox0_reporting_mode
|
||||
RW - trigger / periodic. In "trigger" mode the driver tells two possible
|
||||
values: 0 or prox0_sensor_range value. 0 means no proximity,
|
||||
1023 means proximity. This causes minimal number of interrupts.
|
||||
In "periodic" mode the driver reports all values above
|
||||
prox0_thresh_above. This causes more interrupts, but it can give
|
||||
_rough_ estimate about the distance.
|
||||
|
||||
prox0_reporting_mode_avail
|
||||
RO - accepted values to prox0_reporting_mode (trigger, periodic)
|
||||
|
||||
prox0_thresh_above_value
|
||||
RW - threshold level which trigs proximity events.
|
||||
116
Documentation/misc-devices/bh1770glc.txt
Normal file
116
Documentation/misc-devices/bh1770glc.txt
Normal file
@ -0,0 +1,116 @@
|
||||
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
|
||||
Loading…
Reference in New Issue
Block a user