Pavel Machek wrote:
On Sat 2007-08-11 14:26:02, Yan Burman wrote:
HP Mobile Data Protection System 3D ACPI driver. Similar to hdaps in functionality.
This driver provides 4 kinds of functionality:
1) Creates a misc device /dev/accel that acts similar to /dev/rtc and unblocks
the process reading from it when the device detects free-fall interrupt
2) Functions as an input class device to provide similar functionality to
hdaps, in order to be able to use the laptop as a joystick
3) Provides an interface similar to hdaps, so that hdapsd could work with it
4) Makes it possible to power the device off.
I assume this means 'power the sensor down'? What is interface for
that?
Aha, /sys. Could we simply power off the device when its input device
is not opened?
No, we can't since the sys interface provides the position info and some
applications (hdaps apps for example) use this interface.
It will be very CPU intensive if I power off the device and power it
back on every time /sys/ is read - this stuff goes through ACPI
for each read/write.
+Description
+-----------
+
+This driver provides support for the HP Mobile Data Protection
+System 3D (mdps), which is an accelerometer. HP nc6420, nw9440 and nx9420
+are supported right now, but it may work on other models as well. The
+accelerometer data is readable via /sys/devices/platform/mdps.
+
+Sysfs attributes under /sys/devices/platform/mdps/:
+position - 2D position that the accelerometer reports. Format: "(x,y)"
+position3d - 3D position that the accelerometer reports. Format: "(x,y,z)"
+calibrate - read: values (x, y) that are used as the base for input class device operation.
+ write: forces the base to be recalibrated.
+rate - reports the sampling rate of the accelerometer device in HZ
+state - read: the current power state of the accelerometer device
+ write: "0" or "1" to power on/off the device
+joystick - read: whether the input class device is active or not
+ write: "0" or "1" to enable/disable the input device
+
+Load time parameters:
+bool joystick - whether to enable the input class device or not (default 1)
+bool power_off - whether to power off the device on module load (default 0)
+bool hdaps_compat - Make the driver export same interfaces as hdaps,
+ so that apps like hdaps-gl will work the same as with hdaps (default 0)
+ The effect of this is:
+ 1) Instead of /sys/devices/platform/mdps/, /sys/devices/platform/hdaps/ is created
+ 2) Sensitivity is adjusted to match that of hdaps
+bool input_3d - Whether to operate as a 3D input device. (default 0)
+ BIG FAT WARNING: Do not enable this mode unless you are sure
+ that you want it, since it eats more CPU
+
+This driver also provides an absolute input class device, allowing
+the laptop to act as a pinball machine-esque joystick.
+
Pavel
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