diff options
Diffstat (limited to 'Documentation/misc-devices/lis3lv02d')
| -rw-r--r-- | Documentation/misc-devices/lis3lv02d | 93 |
1 files changed, 0 insertions, 93 deletions
diff --git a/Documentation/misc-devices/lis3lv02d b/Documentation/misc-devices/lis3lv02d deleted file mode 100644 index f89960a0ff95..000000000000 --- a/Documentation/misc-devices/lis3lv02d +++ /dev/null @@ -1,93 +0,0 @@ -Kernel driver lis3lv02d -======================= - -Supported chips: - - * STMicroelectronics LIS3LV02DL, LIS3LV02DQ (12 bits precision) - * STMicroelectronics LIS302DL, LIS3L02DQ, LIS331DL (8 bits) and - LIS331DLH (16 bits) - -Authors: - Yan Burman <burman.yan@gmail.com> - Eric Piel <eric.piel@tremplin-utc.net> - - -Description ------------ - -This driver provides support for the accelerometer found in various HP laptops -sporting the feature officially called "HP Mobile Data Protection System 3D" or -"HP 3D DriveGuard". It detects automatically laptops with this sensor. Known -models (full list can be found in drivers/platform/x86/hp_accel.c) will have -their axis automatically oriented on standard way (eg: you can directly play -neverball). The accelerometer data is readable via -/sys/devices/platform/lis3lv02d. Reported values are scaled -to mg values (1/1000th of earth gravity). - -Sysfs attributes under /sys/devices/platform/lis3lv02d/: -position - 3D position that the accelerometer reports. Format: "(x,y,z)" -rate - read reports the sampling rate of the accelerometer device in HZ. - write changes sampling rate of the accelerometer device. - Only values which are supported by HW are accepted. -selftest - performs selftest for the chip as specified by chip manufacturer. - -This driver also provides an absolute input class device, allowing -the laptop to act as a pinball machine-esque joystick. Joystick device can be -calibrated. Joystick device can be in two different modes. -By default output values are scaled between -32768 .. 32767. In joystick raw -mode, joystick and sysfs position entry have the same scale. There can be -small difference due to input system fuzziness feature. -Events are also available as input event device. - -Selftest is meant only for hardware diagnostic purposes. It is not meant to be -used during normal operations. Position data is not corrupted during selftest -but interrupt behaviour is not guaranteed to work reliably. In test mode, the -sensing element is internally moved little bit. Selftest measures difference -between normal mode and test mode. Chip specifications tell the acceptance -limit for each type of the chip. Limits are provided via platform data -to allow adjustment of the limits without a change to the actual driver. -Seltest returns either "OK x y z" or "FAIL x y z" where x, y and z are -measured difference between modes. Axes are not remapped in selftest mode. -Measurement values are provided to help HW diagnostic applications to make -final decision. - -On HP laptops, if the led infrastructure is activated, support for a led -indicating disk protection will be provided as /sys/class/leds/hp::hddprotect. - -Another feature of the driver is misc device called "freefall" that -acts similar to /dev/rtc and reacts on free-fall interrupts received -from the device. It supports blocking operations, poll/select and -fasync operation modes. You must read 1 bytes from the device. The -result is number of free-fall interrupts since the last successful -read (or 255 if number of interrupts would not fit). See the freefall.c -file for an example on using the device. - - -Axes orientation ----------------- - -For better compatibility between the various laptops. The values reported by -the accelerometer are converted into a "standard" organisation of the axes -(aka "can play neverball out of the box"): - * When the laptop is horizontal the position reported is about 0 for X and Y - and a positive value for Z - * If the left side is elevated, X increases (becomes positive) - * If the front side (where the touchpad is) is elevated, Y decreases - (becomes negative) - * If the laptop is put upside-down, Z becomes negative - -If your laptop model is not recognized (cf "dmesg"), you can send an -email to the maintainer to add it to the database. When reporting a new -laptop, please include the output of "dmidecode" plus the value of -/sys/devices/platform/lis3lv02d/position in these four cases. - -Q&A ---- - -Q: How do I safely simulate freefall? I have an HP "portable -workstation" which has about 3.5kg and a plastic case, so letting it -fall to the ground is out of question... - -A: The sensor is pretty sensitive, so your hands can do it. Lift it -into free space, follow the fall with your hands for like 10 -centimeters. That should be enough to trigger the detection. |