To anyone looking for the MediaTek MT6589 source code, I’ve found one after some digging on a Chinese file sharing website, Baidu Pan. I will provide the link down below, but for now it is only available there. I will mirror it to my Google Drive soon, but it is taking a bit of time. I also have not verified the authenticity of the file yet, so do check back for more updates on this.
Here’s the link: http://pan.baidu.com/s/1qWAu3uc
And a mirror for those who want quicker downloads: https://drive.google.com/open?id=0B71r06Cn5y8SODdDNEd3cDNwcEE&authuser=0