Early Tamil Literature provides evidence of

The ideas of caste discrimination and untouchability find no reference in Sangam Tamil literature.

There is no evidence of casteism and untouchability in Sangam literature. However, a few refrences may be seen in Silapathikaram and Thiruvaimozhi.

It is often argued that presence of term Cheri in Sangam literature is an evidence of existence of caste system as Cheri was regarded as the habitat of low caste. But it has been concluded by research  that it means just a settlement and all the communities had their own cheri.  There is no evidence to prove that the residents of cheri lived in poverty. Everyone pursued his own profession and led a happy life.

Hence the early Tamil Literature does not support the caste system.

Extra info-

One school of thought argue that the 16th century Jesuit missionary Fr Henriques was the first to use the word casta, which later became caste in English.