| Samu Onkalo | 3f0f4a3 | 2010-10-26 14:22:39 -0700 | [diff] [blame] | 1 | Kernel driver bh1770glc |
| 2 | ======================= |
| 3 | |
| 4 | Supported chips: |
| 5 | ROHM BH1770GLC |
| 6 | OSRAM SFH7770 |
| 7 | |
| 8 | Data sheet: |
| 9 | Not freely available |
| 10 | |
| 11 | Author: |
| 12 | Samu Onkalo <samu.p.onkalo@nokia.com> |
| 13 | |
| 14 | Description |
| 15 | ----------- |
| 16 | BH1770GLC and SFH7770 are combined ambient light and proximity sensors. |
| 17 | ALS and proximity parts operates on their own, but they shares common I2C |
| 18 | interface and interrupt logic. In principle they can run on their own, |
| 19 | but ALS side results are used to estimate reliability of the proximity sensor. |
| 20 | |
| 21 | ALS produces 16 bit lux values. The chip contains interrupt logic to produce |
| 22 | low and high threshold interrupts. |
| 23 | |
| 24 | Proximity part contains IR-led driver up to 3 IR leds. The chip measures |
| 25 | amount of reflected IR light and produces proximity result. Resolution is |
| 26 | 8 bit. Driver supports only one channel. Driver uses ALS results to estimate |
| 27 | reliability of the proximity results. Thus ALS is always running while |
| 28 | proximity detection is needed. |
| 29 | |
| 30 | Driver uses threshold interrupts to avoid need for polling the values. |
| 31 | Proximity low interrupt doesn't exists in the chip. This is simulated |
| 32 | by using a delayed work. As long as there is proximity threshold above |
| 33 | interrupts the delayed work is pushed forward. So, when proximity level goes |
| 34 | below the threshold value, there is no interrupt and the delayed work will |
| 35 | finally run. This is handled as no proximity indication. |
| 36 | |
| 37 | Chip state is controlled via runtime pm framework when enabled in config. |
| 38 | |
| 39 | Calibscale factor is used to hide differences between the chips. By default |
| 40 | value set to neutral state meaning factor of 1.00. To get proper values, |
| 41 | calibrated source of light is needed as a reference. Calibscale factor is set |
| 42 | so that measurement produces about the expected lux value. |
| 43 | |
| 44 | SYSFS |
| 45 | ----- |
| 46 | |
| 47 | chip_id |
| 48 | RO - shows detected chip type and version |
| 49 | |
| 50 | power_state |
| 51 | RW - enable / disable chip. Uses counting logic |
| 52 | 1 enables the chip |
| 53 | 0 disables the chip |
| 54 | |
| 55 | lux0_input |
| 56 | RO - measured lux value |
| 57 | sysfs_notify called when threshold interrupt occurs |
| 58 | |
| 59 | lux0_sensor_range |
| 60 | RO - lux0_input max value |
| 61 | |
| 62 | lux0_rate |
| 63 | RW - measurement rate in Hz |
| 64 | |
| 65 | lux0_rate_avail |
| 66 | RO - supported measurement rates |
| 67 | |
| 68 | lux0_thresh_above_value |
| 69 | RW - HI level threshold value. All results above the value |
| 70 | trigs an interrupt. 65535 (i.e. sensor_range) disables the above |
| 71 | interrupt. |
| 72 | |
| 73 | lux0_thresh_below_value |
| 74 | RW - LO level threshold value. All results below the value |
| 75 | trigs an interrupt. 0 disables the below interrupt. |
| 76 | |
| 77 | lux0_calibscale |
| 78 | RW - calibration value. Set to neutral value by default. |
| 79 | Output results are multiplied with calibscale / calibscale_default |
| 80 | value. |
| 81 | |
| 82 | lux0_calibscale_default |
| 83 | RO - neutral calibration value |
| 84 | |
| 85 | prox0_raw |
| 86 | RO - measured proximity value |
| 87 | sysfs_notify called when threshold interrupt occurs |
| 88 | |
| 89 | prox0_sensor_range |
| 90 | RO - prox0_raw max value |
| 91 | |
| 92 | prox0_raw_en |
| 93 | RW - enable / disable proximity - uses counting logic |
| 94 | 1 enables the proximity |
| 95 | 0 disables the proximity |
| 96 | |
| 97 | prox0_thresh_above_count |
| 98 | RW - number of proximity interrupts needed before triggering the event |
| 99 | |
| 100 | prox0_rate_above |
| 101 | RW - Measurement rate (in Hz) when the level is above threshold |
| 102 | i.e. when proximity on has been reported. |
| 103 | |
| 104 | prox0_rate_below |
| 105 | RW - Measurement rate (in Hz) when the level is below threshold |
| 106 | i.e. when proximity off has been reported. |
| 107 | |
| 108 | prox0_rate_avail |
| 109 | RO - Supported proximity measurement rates in Hz |
| 110 | |
| 111 | prox0_thresh_above0_value |
| 112 | RW - threshold level which trigs proximity events. |
| 113 | Filtered by persistence filter (prox0_thresh_above_count) |
| 114 | |
| 115 | prox0_thresh_above1_value |
| 116 | RW - threshold level which trigs event immediately |