Tranist visa allowed?

Swiss passport

I travel to india in november and after that i would like to visit shanghai before i go back home. So i already have a return ticket to/from delhi back home. Can i get a free transit when i fly from DEL to PVG via HKG and back PVG/HKG/DEL/ZRH or is only the arrival/departure flight to/from Shanghai important to get a free transit? Or do i need an other flight to get the visa?