Every ring seems to have the concept of read and
write pointers. Make the register offset variable
so we can use the functions for different types of rings.
Signed-off-by: NChristian König <deathsimple@vodafone.de>
Reviewed-by: NJerome Glisse <jglisse@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>