Source:
http://www.morganstanleychina.com/conferences/apsummit2011/research/63ICManufacturingFoundries.pdf
It doesn't out right say it but it gives you reasons why and I'll help with that. It is before AMD cancelled 28-nm APU at GlobalFoundries as well.
With the bulk of quotes gone: Nvidia Kepler and AMD Jaguar were both done on TSMC's HP offering. AMD Tahiti, Pitcarn, Cape Verde, Bonaire is up in the air for HPL or HPM or HP.
Image #1: (July 2013?)
http://i.imgur.com/kF1Ocon.jpg
GloFo's HPP which is the competitor of TSMC's HP wasn't finished in 2012.
http://ir.amd.com/phoenix.zhtml?c=74093&p=quarterlyearnings
2012 Q4 QE, Transcript.
Rory Read:We had a really awesome 28-nm GPU supply chain and we are refocusing all our efforts towards that supply chain. While, we wait for GlobalFoundries to catch up.
Here comes the damage control
Lisa Su:Thank Goodness, for TSMC or we would have had to wait till 2015!