Kodak Black in Solitary Confinement

Kodak Black is in solitary confinement ... TMZ has learned.

It appears from legal docs he was taken out of general population after he used the prison phone to make a 3-way call which is prohibited by prison rules. He was given 30 days in the hole for that violation.

The rapper -- who is currently behind bars in Florida -- filed legal docs asking the judge to allow him to have his tutor visit while he is in solitary because he wants to get his GED. In docs, filed by attorney Bradford Cohen and obtained by TMZ, Kodak also asks for access to a laptop and adds prior to getting jailed, he was studying for his GED.

The judge has yet to rule.