MIPS: SMP-CPS: Add support for irq migration when CPU offline

Currently we won't migrate irqs when offline CPUs, which has been
implemented on most architectures. That will lead to some devices work
incorrectly if the bound cores are offline.

While that can be easily supported by enabling GENERIC_IRQ_MIGRATION.
But i don't pretty known the reason it was not supported on all MIPS
platforms.

This patch add the support for irq migration on MIPS CPS platform, and
it's tested on the interAptiv processor.
Signed-off-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/Kconfig

@@ -2488,6 +2488,7 @@ config MIPS_CPS
 	select SYS_SUPPORTS_SCHED_SMT if CPU_MIPSR6
 	select SYS_SUPPORTS_SMP
 	select WEAK_ORDERING
+	select GENERIC_IRQ_MIGRATION if HOTPLUG_CPU
 	help
 	  Select this if you wish to run an SMP kernel across multiple cores
 	  within a MIPS Coherent Processing System. When this option is

arch/mips/kernel/smp-cps.c

@@ -12,6 +12,7 @@
 #include <linux/slab.h>
 #include <linux/smp.h>
 #include <linux/types.h>
+#include <linux/irq.h>
 
 #include <asm/bcache.h>
 #include <asm/mips-cps.h>
@@ -461,6 +462,7 @@ static int cps_cpu_disable(void)
 	smp_mb__after_atomic();
 	set_cpu_online(cpu, false);
 	calculate_cpu_foreign_map();
+	irq_migrate_all_off_this_cpu();
 
 	return 0;
 }