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Message-Id: <1287472188-10101-6-git-send-email-samu.p.onkalo@nokia.com> Date: Tue, 19 Oct 2010 10:09:48 +0300 From: Samu Onkalo <samu.p.onkalo@...ia.com> To: akpm@...ux-foundation.org Cc: linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org Subject: [PATCHv4 5/5] 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@...ia.com> Acked-by: Jonathan Cameron <jic23@....ac.uk> --- Documentation/misc-devices/apds990x.txt | 111 ++++++++++++++++++++++++++++ Documentation/misc-devices/bh1770glc.txt | 116 ++++++++++++++++++++++++++++++ 2 files changed, 227 insertions(+), 0 deletions(-) create mode 100644 Documentation/misc-devices/apds990x.txt create mode 100644 Documentation/misc-devices/bh1770glc.txt diff --git a/Documentation/misc-devices/apds990x.txt b/Documentation/misc-devices/apds990x.txt new file mode 100644 index 0000000..d5408ca --- /dev/null +++ b/Documentation/misc-devices/apds990x.txt @@ -0,0 +1,111 @@ +Kernel driver apds990x +====================== + +Supported chips: +Avago APDS990X + +Data sheet: +Not freely available + +Author: +Samu Onkalo <samu.p.onkalo@...ia.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. diff --git a/Documentation/misc-devices/bh1770glc.txt b/Documentation/misc-devices/bh1770glc.txt new file mode 100644 index 0000000..7d64c01 --- /dev/null +++ b/Documentation/misc-devices/bh1770glc.txt @@ -0,0 +1,116 @@ +Kernel driver bh1770glc +======================= + +Supported chips: +ROHM BH1770GLC +OSRAM SFH7770 + +Data sheet: +Not freely available + +Author: +Samu Onkalo <samu.p.onkalo@...ia.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 -- 1.6.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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