  In this paper we study the relativistic quantum dynamics of a massless
fermion confined in a quantum ring. We use a model of confining potential and
introduce the interaction via Dirac oscillator coupling, which provides ring
confinement for massless Dirac fermions. We obtain the energy levels and
corresponding eigenfuctions for this model in graphene layer in the presence of
Aharonov-Bohm flux in the centre of the ring and the expression for persistent
current in this model. We also investigate the model for quantum ring in
graphene layer in the presence of disclination and magnetic flux. The energy
spectrum and wave function are obtained exactly for this case. We see that the
persistent current depends in parameters characterizing the topological defect.
