GTP, GGSN and PGW testing

Hi, Currently i am working in LTE and would like to test SGW and PDN-GW along with GTP protocol for my research aspect. I have already worked and used OpenairInterface EPC. But, i wanted to explore other kernel or user-space options of GTP. Please let me know the procedure to access the code of , (i) Latest mainline linux kernel version with your GTP code and user space GTP module. (ii) Also, could you please kindly provide me access to the SGW/GGSN and PGW codes. Please kindly provide me access to the latest code, such that i could test it and will even post the test results to the community. Thanks & Regards Vasu.