[PATCH v2] powerpc: don't enable cpu hotplug on mpic-based pseries

[Milton Miller]

Don't allow cpu hotplug on pSeries systems lacking XICS interrupt controller,
since current code is hardcoded to call xics routines.

Signed-off-by: Milton Miller <miltonm at bga.com>
--

Olof's patch searched the device-tree again, looking for an mpic.   This
code instead checks that we found an xics the first time by checking the
init function.

diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 9711eb0..20f010a 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -262,6 +262,12 @@ static int __init pseries_cpu_hotplug_init(void)
 		return 0;
 	}
 
+	if (ppc_md.init_IRQ != xics_init_IRQ) {
+		printk(KERN_INFO "pSeries CPU Hotplug only supported on xics "
+				"interrupt controllers - disabling");
+		return 0;
+	}
+
 	ppc_md.cpu_die = pseries_mach_cpu_die;
 	smp_ops->cpu_disable = pseries_cpu_disable;
 	smp_ops->cpu_die = pseries_cpu_die;