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Based on kernel version 2.6.32. Page generated on 2009-12-11 16:22 EST.

1	Kernel driver lis3lv02d
2	=======================
3	
4	Supported chips:
5	
6	  * STMicroelectronics LIS3LV02DL and LIS3LV02DQ
7	
8	Authors:
9	        Yan Burman <burman.yan[AT]gmail[DOT]com>
10		Eric Piel <eric.piel[AT]tremplin-utc[DOT]net>
11	
12	
13	Description
14	-----------
15	
16	This driver provides support for the accelerometer found in various HP
17	laptops sporting the feature officially called "HP Mobile Data
18	Protection System 3D" or "HP 3D DriveGuard". It detects automatically
19	laptops with this sensor. Known models (for now the HP 2133, nc6420,
20	nc2510, nc8510, nc84x0, nw9440 and nx9420) will have their axis
21	automatically oriented on standard way (eg: you can directly play
22	neverball).  The accelerometer data is readable via
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)"
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
30			   position.
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	
36	Another feature of the driver is misc device called "freefall" that
37	acts similar to /dev/rtc and reacts on free-fall interrupts received
38	from the device. It supports blocking operations, poll/select and
39	fasync operation modes. You must read 1 bytes from the device.  The
40	result is number of free-fall interrupts since the last successful
41	read (or 255 if number of interrupts would not fit).
42	
43	
44	Axes orientation
45	----------------
46	
47	For better compatibility between the various laptops. The values reported by
48	the accelerometer are converted into a "standard" organisation of the axes
49	(aka "can play neverball out of the box"):
50	 * When the laptop is horizontal the position reported is about 0 for X and Y
51		and a positive value for Z
52	 * If the left side is elevated, X increases (becomes positive)
53	 * If the front side (where the touchpad is) is elevated, Y decreases
54		(becomes negative)
55	 * If the laptop is put upside-down, Z becomes negative
56	
57	If your laptop model is not recognized (cf "dmesg"), you can send an
58	email to the authors to add it to the database.  When reporting a new
59	laptop, please include the output of "dmidecode" plus the value of
60	/sys/devices/platform/lis3lv02d/position in these four cases.
61	
62	Q&A
63	---
64	
65	Q: How do I safely simulate freefall? I have an HP "portable
66	workstation" which has about 3.5kg and a plastic case, so letting it
67	fall to the ground is out of question...
68	
69	A: The sensor is pretty sensitive, so your hands can do it. Lift it
70	into free space, follow the fall with your hands for like 10
71	centimeters. That should be enough to trigger the detection.
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