Pavel Machek | 455fbdd | 2008-11-12 13:27:02 -0800 | [diff] [blame] | 1 | Kernel driver lis3lv02d |
Pavel Machek | 2b87290 | 2009-03-31 15:24:25 -0700 | [diff] [blame] | 2 | ======================= |
Pavel Machek | 455fbdd | 2008-11-12 13:27:02 -0800 | [diff] [blame] | 3 | |
| 4 | Supported chips: |
| 5 | |
Éric Piel | bc62c14 | 2009-12-14 18:01:39 -0800 | [diff] [blame] | 6 | * STMicroelectronics LIS3LV02DL, LIS3LV02DQ (12 bits precision) |
| 7 | * STMicroelectronics LIS302DL, LIS3L02DQ, LIS331DL (8 bits) |
Pavel Machek | 455fbdd | 2008-11-12 13:27:02 -0800 | [diff] [blame] | 8 | |
Pavel Machek | 2b87290 | 2009-03-31 15:24:25 -0700 | [diff] [blame] | 9 | Authors: |
Pavel Machek | 455fbdd | 2008-11-12 13:27:02 -0800 | [diff] [blame] | 10 | Yan Burman <burman.yan@gmail.com> |
| 11 | Eric Piel <eric.piel@tremplin-utc.net> |
| 12 | |
| 13 | |
| 14 | Description |
| 15 | ----------- |
| 16 | |
Éric Piel | bc62c14 | 2009-12-14 18:01:39 -0800 | [diff] [blame] | 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/hwmon/hp_accel.c) will have their |
| 21 | axis automatically oriented on standard way (eg: you can directly play |
| 22 | neverball). The accelerometer data is readable via |
Pavel Machek | 455fbdd | 2008-11-12 13:27:02 -0800 | [diff] [blame] | 23 | /sys/devices/platform/lis3lv02d. |
| 24 | |
| 25 | Sysfs attributes under /sys/devices/platform/lis3lv02d/: |
| 26 | position - 3D position that the accelerometer reports. Format: "(x,y,z)" |
Pavel Machek | 219beb2 | 2009-01-15 13:51:24 -0800 | [diff] [blame] | 27 | calibrate - read: values (x, y, z) that are used as the base for input |
| 28 | class device operation. |
| 29 | write: forces the base to be recalibrated with the current |
Pavel Machek | 2b87290 | 2009-03-31 15:24:25 -0700 | [diff] [blame] | 30 | position. |
Pavel Machek | 455fbdd | 2008-11-12 13:27:02 -0800 | [diff] [blame] | 31 | rate - reports the sampling rate of the accelerometer device in HZ |
| 32 | |
| 33 | This driver also provides an absolute input class device, allowing |
| 34 | the laptop to act as a pinball machine-esque joystick. |
| 35 | |
Éric Piel | bc62c14 | 2009-12-14 18:01:39 -0800 | [diff] [blame] | 36 | On HP laptops, if the led infrastructure is activated, support for a led |
| 37 | indicating disk protection will be provided as /sys/class/leds/hp::hddprotect. |
| 38 | |
Pavel Machek | ef2cfc7 | 2009-02-18 14:48:23 -0800 | [diff] [blame] | 39 | Another feature of the driver is misc device called "freefall" that |
| 40 | acts similar to /dev/rtc and reacts on free-fall interrupts received |
| 41 | from the device. It supports blocking operations, poll/select and |
| 42 | fasync operation modes. You must read 1 bytes from the device. The |
| 43 | result is number of free-fall interrupts since the last successful |
Éric Piel | bc62c14 | 2009-12-14 18:01:39 -0800 | [diff] [blame] | 44 | read (or 255 if number of interrupts would not fit). See the hpfall.c |
| 45 | file for an example on using the device. |
Pavel Machek | ef2cfc7 | 2009-02-18 14:48:23 -0800 | [diff] [blame] | 46 | |
| 47 | |
Pavel Machek | 455fbdd | 2008-11-12 13:27:02 -0800 | [diff] [blame] | 48 | Axes orientation |
| 49 | ---------------- |
| 50 | |
| 51 | For better compatibility between the various laptops. The values reported by |
| 52 | the accelerometer are converted into a "standard" organisation of the axes |
| 53 | (aka "can play neverball out of the box"): |
| 54 | * When the laptop is horizontal the position reported is about 0 for X and Y |
Pavel Machek | 2b87290 | 2009-03-31 15:24:25 -0700 | [diff] [blame] | 55 | and a positive value for Z |
Pavel Machek | 455fbdd | 2008-11-12 13:27:02 -0800 | [diff] [blame] | 56 | * If the left side is elevated, X increases (becomes positive) |
Pavel Machek | 219beb2 | 2009-01-15 13:51:24 -0800 | [diff] [blame] | 57 | * If the front side (where the touchpad is) is elevated, Y decreases |
| 58 | (becomes negative) |
Pavel Machek | 455fbdd | 2008-11-12 13:27:02 -0800 | [diff] [blame] | 59 | * If the laptop is put upside-down, Z becomes negative |
| 60 | |
Pavel Machek | 219beb2 | 2009-01-15 13:51:24 -0800 | [diff] [blame] | 61 | If your laptop model is not recognized (cf "dmesg"), you can send an |
Éric Piel | bc62c14 | 2009-12-14 18:01:39 -0800 | [diff] [blame] | 62 | email to the maintainer to add it to the database. When reporting a new |
Pavel Machek | 219beb2 | 2009-01-15 13:51:24 -0800 | [diff] [blame] | 63 | laptop, please include the output of "dmidecode" plus the value of |
| 64 | /sys/devices/platform/lis3lv02d/position in these four cases. |
Pavel Machek | 455fbdd | 2008-11-12 13:27:02 -0800 | [diff] [blame] | 65 | |
Pavel Machek | 2b87290 | 2009-03-31 15:24:25 -0700 | [diff] [blame] | 66 | Q&A |
| 67 | --- |
| 68 | |
| 69 | Q: How do I safely simulate freefall? I have an HP "portable |
| 70 | workstation" which has about 3.5kg and a plastic case, so letting it |
| 71 | fall to the ground is out of question... |
| 72 | |
| 73 | A: The sensor is pretty sensitive, so your hands can do it. Lift it |
| 74 | into free space, follow the fall with your hands for like 10 |
| 75 | centimeters. That should be enough to trigger the detection. |