hp accelerometer: add freefall detection

This adds freefall handling to hp_accel driver.  According to HP, it
should just work, without us having to set the chip up by hand.

hpfall.c is example .c program that parks the disk when accelerometer
detects free fall.  It should work; for now, it uses fixed 20seconds
protection period.

Signed-off-by: Pavel Machek <pavel@suse.cz>
Cc: Thomas Renninger <trenn@suse.de>
Cc: Éric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Pavel Machek
2009-02-18 14:48:23 -08:00
committed by Linus Torvalds
parent 3a5093ee67
commit ef2cfc790b
5 changed files with 296 additions and 17 deletions

View File

@@ -33,6 +33,14 @@ rate - reports the sampling rate of the accelerometer device in HZ
This driver also provides an absolute input class device, allowing
the laptop to act as a pinball machine-esque joystick.
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).
Axes orientation
----------------