Add user APIs through ioctl to allocate, free, and be notified of an AFU interrupt. For opencapi, an AFU can trigger an interrupt on the host by sending a specific command targeting a 64-bit object handle. On POWER9, this is implemented by mapping a special page in the address space of a process and a write to that page will trigger an interrupt. Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>