MIPS: Netlogic: Fix plat_irq_dispatch

Fix an issue in plat_irq_dispatch due to which it can call do_IRQ
with a PIC irq that is not mapped.

When a per-cpu interrupt and a PIC interrupt are both active, the
check 'eirr & PERCPU_IRQ_MASK' will be true, but the interrupt in 'i'
will be the number of the PIC interrupt. In this case, we will call
do_IRQ on the PIC interrupt without mapping it with nlm_irq_to_xirq().

Fix this by using __ffs64 instead of __ilog2_u64 and using the
interrupt number instead of mask to identify per-cpu interrupts.
Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5432/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/netlogic/common/irq.c

@@ -253,13 +253,12 @@ asmlinkage void plat_irq_dispatch(void)
 
 	node = nlm_nodeid();
 	eirr = read_c0_eirr_and_eimr();
-
-	i = __ilog2_u64(eirr);
-	if (i == -1)
+	if (eirr == 0)
 		return;
 
+	i = __ffs64(eirr);
 	/* per-CPU IRQs don't need translation */
-	if (eirr & PERCPU_IRQ_MASK) {
+	if (i < PIC_IRQ_BASE) {
 		do_IRQ(i);
 		return;
 	}