diff options
Diffstat (limited to 'Documentation/hwmon/lis3lv02d')
| -rw-r--r-- | Documentation/hwmon/lis3lv02d | 92 |
1 files changed, 0 insertions, 92 deletions
diff --git a/Documentation/hwmon/lis3lv02d b/Documentation/hwmon/lis3lv02d deleted file mode 100644 index f1a4ec840f86..000000000000 --- a/Documentation/hwmon/lis3lv02d +++ /dev/null | |||
| @@ -1,92 +0,0 @@ | |||
| 1 | Kernel driver lis3lv02d | ||
| 2 | ======================= | ||
| 3 | |||
| 4 | Supported chips: | ||
| 5 | |||
| 6 | * STMicroelectronics LIS3LV02DL, LIS3LV02DQ (12 bits precision) | ||
| 7 | * STMicroelectronics LIS302DL, LIS3L02DQ, LIS331DL (8 bits) | ||
| 8 | |||
| 9 | Authors: | ||
| 10 | Yan Burman <burman.yan@gmail.com> | ||
| 11 | Eric Piel <eric.piel@tremplin-utc.net> | ||
| 12 | |||
| 13 | |||
| 14 | Description | ||
| 15 | ----------- | ||
| 16 | |||
| 17 | This driver provides support for the accelerometer found in various HP laptops | ||
| 18 | sporting the feature officially called "HP Mobile Data Protection System 3D" or | ||
| 19 | "HP 3D DriveGuard". It detects automatically laptops with this sensor. Known | ||
| 20 | models (full list can be found in drivers/platform/x86/hp_accel.c) will have | ||
| 21 | their axis automatically oriented on standard way (eg: you can directly play | ||
| 22 | neverball). The accelerometer data is readable via | ||
| 23 | /sys/devices/platform/lis3lv02d. Reported values are scaled | ||
| 24 | to mg values (1/1000th of earth gravity). | ||
| 25 | |||
| 26 | Sysfs attributes under /sys/devices/platform/lis3lv02d/: | ||
| 27 | position - 3D position that the accelerometer reports. Format: "(x,y,z)" | ||
| 28 | rate - read reports the sampling rate of the accelerometer device in HZ. | ||
| 29 | write changes sampling rate of the accelerometer device. | ||
| 30 | Only values which are supported by HW are accepted. | ||
| 31 | selftest - performs selftest for the chip as specified by chip manufacturer. | ||
| 32 | |||
| 33 | This driver also provides an absolute input class device, allowing | ||
| 34 | the laptop to act as a pinball machine-esque joystick. Joystick device can be | ||
| 35 | calibrated. Joystick device can be in two different modes. | ||
| 36 | By default output values are scaled between -32768 .. 32767. In joystick raw | ||
| 37 | mode, joystick and sysfs position entry have the same scale. There can be | ||
| 38 | small difference due to input system fuzziness feature. | ||
| 39 | Events are also available as input event device. | ||
| 40 | |||
| 41 | Selftest is meant only for hardware diagnostic purposes. It is not meant to be | ||
| 42 | used during normal operations. Position data is not corrupted during selftest | ||
| 43 | but interrupt behaviour is not guaranteed to work reliably. In test mode, the | ||
| 44 | sensing element is internally moved little bit. Selftest measures difference | ||
| 45 | between normal mode and test mode. Chip specifications tell the acceptance | ||
| 46 | limit for each type of the chip. Limits are provided via platform data | ||
| 47 | to allow adjustment of the limits without a change to the actual driver. | ||
| 48 | Seltest returns either "OK x y z" or "FAIL x y z" where x, y and z are | ||
| 49 | measured difference between modes. Axes are not remapped in selftest mode. | ||
| 50 | Measurement values are provided to help HW diagnostic applications to make | ||
| 51 | final decision. | ||
| 52 | |||
| 53 | On HP laptops, if the led infrastructure is activated, support for a led | ||
| 54 | indicating disk protection will be provided as /sys/class/leds/hp::hddprotect. | ||
| 55 | |||
| 56 | Another feature of the driver is misc device called "freefall" that | ||
| 57 | acts similar to /dev/rtc and reacts on free-fall interrupts received | ||
| 58 | from the device. It supports blocking operations, poll/select and | ||
| 59 | fasync operation modes. You must read 1 bytes from the device. The | ||
| 60 | result is number of free-fall interrupts since the last successful | ||
| 61 | read (or 255 if number of interrupts would not fit). See the hpfall.c | ||
| 62 | file for an example on using the device. | ||
| 63 | |||
| 64 | |||
| 65 | Axes orientation | ||
| 66 | ---------------- | ||
| 67 | |||
| 68 | For better compatibility between the various laptops. The values reported by | ||
| 69 | the accelerometer are converted into a "standard" organisation of the axes | ||
| 70 | (aka "can play neverball out of the box"): | ||
| 71 | * When the laptop is horizontal the position reported is about 0 for X and Y | ||
| 72 | and a positive value for Z | ||
| 73 | * If the left side is elevated, X increases (becomes positive) | ||
| 74 | * If the front side (where the touchpad is) is elevated, Y decreases | ||
| 75 | (becomes negative) | ||
| 76 | * If the laptop is put upside-down, Z becomes negative | ||
| 77 | |||
| 78 | If your laptop model is not recognized (cf "dmesg"), you can send an | ||
| 79 | email to the maintainer to add it to the database. When reporting a new | ||
| 80 | laptop, please include the output of "dmidecode" plus the value of | ||
| 81 | /sys/devices/platform/lis3lv02d/position in these four cases. | ||
| 82 | |||
| 83 | Q&A | ||
| 84 | --- | ||
| 85 | |||
| 86 | Q: How do I safely simulate freefall? I have an HP "portable | ||
| 87 | workstation" which has about 3.5kg and a plastic case, so letting it | ||
| 88 | fall to the ground is out of question... | ||
| 89 | |||
| 90 | A: The sensor is pretty sensitive, so your hands can do it. Lift it | ||
| 91 | into free space, follow the fall with your hands for like 10 | ||
| 92 | centimeters. That should be enough to trigger the detection. | ||