suse man page for struct_ff_effect

STRUCT 
FF_EFFECT(9)						  Input Subsystem					       STRUCT FF_EFFECT(9)

NAME
       struct_ff_effect - defines force feedback effect

SYNOPSIS
       struct ff_effect {
	 __u16 type;
	 __s16 id;
	 __u16 direction;
	 struct ff_trigger trigger;
	 struct ff_replay replay;
	 union u;
       };

MEMBERS
       type
	   type of the effect (FF_CONSTANT, FF_PERIODIC, FF_RAMP, FF_SPRING, FF_FRICTION, FF_DAMPER, FF_RUMBLE, FF_INERTIA, or FF_CUSTOM)

       id
	   an unique id assigned to an effect

       direction
	   direction of the effect

       trigger
	   trigger conditions (struct ff_trigger)

       replay
	   scheduling of the effect (struct ff_replay)

       u
	   effect-specific structure (one of ff_constant_effect, ff_ramp_effect, ff_periodic_effect, ff_condition_effect, ff_rumble_effect)
	   further defining effect parameters

DESCRIPTION
       This structure is sent through ioctl from the application to the driver. To create a new effect application should set its id to -1; the
       kernel will return assigned id which can later be used to update or delete this effect.

DIRECTION OF THE EFFECT IS ENCODED AS FOLLOWS
       0 deg -> 0x0000 (down) 90 deg -> 0x4000 (left) 180 deg -> 0x8000 (up) 270 deg -> 0xC000 (right)

COPYRIGHT
Kernel Hackers Manual 2.6.					     July 2010						       STRUCT FF_EFFECT(9)