Regarding driver interface for user space

Hi, What interfaces are provided by device drivers, in general, to user space to access status and other information ? For example, if have enabled rotatry encoder driver and touchscreen driver, how can write code in my application which will process rotatry encoder data like how many relative or absolute rotation happened, if these were clockwise or counter clockwise, etc. And in case of touchscreen driver, touch events ? Thanks, Rahul Bedarkar