The MIPI DSI (Mobile Industry Platform Alliance Display Serial Interface) is the current industry standard for interfacing most smartphone LCDs to the device's CPU/GPU. MIPI is a consortium of mobile (and other) hardware vendors that standardized interfaces of many handset internals (for example CSI for camera modules).
The bad news is, MIPI's specifications are available after signing and NDA and paying a fee. The good one is: there's enough bits of information available in the Web to put together a working DSI host. Here are some links: