powerpc/powernv: Increase opal-irqchip initcall priority

The eeh subsystem for powernv requires the opal event irqchip to be
initialised prior to initialisation or the following errors are
produced (and eeh doesn't work as expected):

irq: XICS didn't like hwirq-0x9 to VIRQ17 mapping (rc=-22)
pnv_eeh_post_init: Can't request OPAL event interrupt (0)

On powernv eeh is initialised from a subsys_initcall due to a check
for machine_is(powernv) in eeh_init(). This patch increases the
initcall priority of opal_event_init() to an arch_initcall to ensure
the opal event interface is initialised prior to any users of it.
Signed-off-by: Alistair Popple <alistair@popple.id.au>
Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/powernv/opal-irqchip.c

@@ -231,6 +231,7 @@ int __init opal_event_init(void)
 	of_node_put(opal_node);
 	return rc;
 }
+machine_arch_initcall(powernv, opal_event_init);
 
 /**
  * opal_event_request(unsigned int opal_event_nr) - Request an event
@@ -244,6 +245,9 @@ int __init opal_event_init(void)
  */
 int opal_event_request(unsigned int opal_event_nr)
 {
+	if (WARN_ON_ONCE(!opal_event_irqchip.domain))
+		return NO_IRQ;
+
 	return irq_create_mapping(opal_event_irqchip.domain, opal_event_nr);
 }
 EXPORT_SYMBOL(opal_event_request);

arch/powerpc/platforms/powernv/opal.c

@@ -657,9 +657,6 @@ static int __init opal_init(void)
 		return -ENODEV;
 	}
 
-	/* Initialise OPAL events */
-	opal_event_init();
-
 	/* Register OPAL consoles if any ports */
 	if (firmware_has_feature(FW_FEATURE_OPALv2))
 		consoles = of_find_node_by_path("/ibm,opal/consoles");