Getting the PS4 controller to work with Windows is a bit tough. Steam hopes to ease the process, at least for its beta testers. The beta client adds PS4 controller support. Once you set up the controller, it should let you map out things like the buttons as well as the trackpad to anything you want. Some might need to get the dongle for Sony to have this work. But games can also directly support the controller if the developers want. The controller event gets access to everything done by the Steam Controller. So, if you’re not a fan of the official controller, you can opt to use this. Opt into beta if you want to try this feature out.
Source: Lifehacker