Most recent Canon lenses will work in AF mode with the Metabones smart adapter (even the 50 f/1.4, which is not reported to work but I've just tried mine and it does :) Your Tamron is reported to work.
"Work" is however a relative term, autofocus may function but it will be incredibly slow and can be unreliable. Other electronic functions such as automatic aperture, IS and EXIF reporting work fine.
On the plus side manual focus is a breeze on the A7 series compared to Canon DSLRs due to focus magnification and peaking. For landscape and studio work you should be ok, for events or sports it will take skill and practice to get good results with the A7 and Canon lenses.