http://libSDL.org/ - Simple DirectMedia Layer SDL is a cross-platform multimedia library designed to provide low level access to audio, keyboard, mouse, joystick, 3D hardware via OpenGL, and 2D video framebuffer.
There is a tcl interface - package require mkLibsdl - and some demo scripts joystick(1-5).tcl to get status information from the gamepad or joystick http://mkextensions.sourceforge.net/ .