powerpc/mpic: Add ability to reset a core via MPIC

We need the ability to reset cores for use with kexec/kdump for
SMP systems. Calling this function with the specific core you want
to reset will cause the CPU to spin in reset.
Signed-off-by: Matthew McClintock <msm@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/sysdev/mpic.c

@@ -1636,6 +1636,24 @@ void __devinit smp_mpic_setup_cpu(int cpu)
 {
 	mpic_setup_this_cpu();
 }
+
+void mpic_reset_core(int cpu)
+{
+	struct mpic *mpic = mpic_primary;
+	u32 pir;
+	int cpuid = get_hard_smp_processor_id(cpu);
+
+	/* Set target bit for core reset */
+	pir = mpic_read(mpic->gregs, MPIC_INFO(GREG_PROCESSOR_INIT));
+	pir |= (1 << cpuid);
+	mpic_write(mpic->gregs, MPIC_INFO(GREG_PROCESSOR_INIT), pir);
+	mpic_read(mpic->gregs, MPIC_INFO(GREG_PROCESSOR_INIT));
+
+	/* Restore target bit after reset complete */
+	pir &= ~(1 << cpuid);
+	mpic_write(mpic->gregs, MPIC_INFO(GREG_PROCESSOR_INIT), pir);
+	mpic_read(mpic->gregs, MPIC_INFO(GREG_PROCESSOR_INIT));
+}
 #endif /* CONFIG_SMP */
 
 #ifdef CONFIG_PM

arch/powerpc/sysdev/mpic.h

@@ -37,5 +37,6 @@ static inline int mpic_pasemi_msi_init(struct mpic *mpic)
 extern int mpic_set_irq_type(unsigned int virq, unsigned int flow_type);
 extern void mpic_set_vector(unsigned int virq, unsigned int vector);
 extern int mpic_set_affinity(unsigned int irq, const struct cpumask *cpumask);
+extern void mpic_reset_core(int cpu);
 
 #endif /* _POWERPC_SYSDEV_MPIC_H */