imx233: fix IRQ handler w.r.t unwinder

The IRQ handler saves registers on the IRQ stack, saves the old PC to imx233
HW_DIGCTL_SCRATCH0 register and switcht to SVC for the actual handling. The
old code had a problem in that if the unwinder is called during the IRQ (for
example by the watchdog), then __get_sp() will use SPSR_svc to discover the
previous mode, switch to it and recover SP. But SPSR_svc is invalid, it should
be SPSR_irq but we switch from IRQ to SVC mode. The new code copies SPSR_irq
to SPSR_svc in IRQ to fix this problem. It also saves/restore SCRATCH0 in
case I one day renable nested interrupts or use SCRATCH0 for other purposes.
I also changed the old watchdog code to call UIE directly instead of trying
to make the code crash with a SWI.

Change-Id: Id87462d410764b019bd2aa9adc71cb917ade32e3

0 files changed, 0 insertions, 0 deletions