tree d6a58bc7c9b615bb90f88ed5bbb7f6a5a38e3df5
parent 1ca0c808c60f171c1949b0e7f3a4c0516855f7a0
author Daniel Hellstrom <daniel@gaisler.com> 1304294933 +0000
committer David S. Miller <davem@davemloft.net> 1305576464 -0700

sparc32, sun4m: Implemented SMP IPIs support for SUN4M machines

Implement the three IPIs (resched, single and cpu-mask) generation
and interrupt handler catch. The sun4m has 15 soft-IRQs and three
of them is used with this patch, the three IPIs was previously
implemented with the cross-call IRQ15 which does not work with
locking routines such as spinlocks because IRQ15 is NMI, it may
cause deadlock.

The IRQ trap handler code assumes (in the same spritit as the old
it seems) that hard interrupts will be generated until handled
(level), when a IRQ happens the IRQ pending register is checked
for pending soft-IRQs. When both hard and soft IRQ happens at the
same time only soft-IRQs are handled.

The old code implemented a soft-IRQ traphandler at IRQ14 which
called smp_reschedule_irq which in turn called set_need_resched.
It seems to be an old relic and is replaced with the interrupt
traphander exit code RESTORE_ALL, it calls schedule() when
appropriate.

Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
Signed-off-by: David S. Miller <davem@davemloft.net>