path: root/Documentation/misc-devices/bh1770glc.txt
diff options
authorFathi Boudra <fathi.boudra@linaro.org>2013-04-28 09:33:08 +0300
committerFathi Boudra <fathi.boudra@linaro.org>2013-04-28 09:33:08 +0300
commit3b4bd47f8f4ed3aaf7c81c9b5d2d37ad79fadf4a (patch)
treeb9996006addfd7ae70a39672b76843b49aebc189 /Documentation/misc-devices/bh1770glc.txt
Imported Upstream version 3.9.0HEADupstream/3.9.0upstreammaster
Diffstat (limited to 'Documentation/misc-devices/bh1770glc.txt')
1 files changed, 116 insertions, 0 deletions
diff --git a/Documentation/misc-devices/bh1770glc.txt b/Documentation/misc-devices/bh1770glc.txt
new file mode 100644
index 00000000..7d64c014
--- /dev/null
+++ b/Documentation/misc-devices/bh1770glc.txt
@@ -0,0 +1,116 @@
+Kernel driver bh1770glc
+Supported chips:
+Data sheet:
+Not freely available
+Samu Onkalo <samu.p.onkalo@nokia.com>
+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.
+ RO - shows detected chip type and version
+ RW - enable / disable chip. Uses counting logic
+ 1 enables the chip
+ 0 disables the chip
+ RO - measured lux value
+ sysfs_notify called when threshold interrupt occurs
+ RO - lux0_input max value
+ RW - measurement rate in Hz
+ RO - supported measurement rates
+ RW - HI level threshold value. All results above the value
+ trigs an interrupt. 65535 (i.e. sensor_range) disables the above
+ interrupt.
+ RW - LO level threshold value. All results below the value
+ trigs an interrupt. 0 disables the below interrupt.
+ RW - calibration value. Set to neutral value by default.
+ Output results are multiplied with calibscale / calibscale_default
+ value.
+ RO - neutral calibration value
+ RO - measured proximity value
+ sysfs_notify called when threshold interrupt occurs
+ RO - prox0_raw max value
+ RW - enable / disable proximity - uses counting logic
+ 1 enables the proximity
+ 0 disables the proximity
+ RW - number of proximity interrupts needed before triggering the event
+ RW - Measurement rate (in Hz) when the level is above threshold
+ i.e. when proximity on has been reported.
+ RW - Measurement rate (in Hz) when the level is below threshold
+ i.e. when proximity off has been reported.
+ RO - Supported proximity measurement rates in Hz
+ RW - threshold level which trigs proximity events.
+ Filtered by persistence filter (prox0_thresh_above_count)
+ RW - threshold level which trigs event immediately