On my T4240 boards I get the invalid value from the MPIC_WHOAMI register which prevents the required operation of the MPIC_IPIDR# registers. Secondary CPU cores can signal the boot core but the boot core cannot signal the secondary CPU's.
I suspect this is a configuration problem with the MPIC but I have been unable to find adequate details in the T4240RM document to discover how.
Has anybody else encountered this problem on T4240 cores? Is there a suitable work around for core directed interrupts?