core/ipmi-opal: Add interrupt-parent property for ipmi node on P9 and…

… above.

dtc complains below warning with newer 4.2+ kernels.
dts: Warning
(interrupts_property): Missing interrupt-parent for /ibm,opal/ipmi

This fix adds interrupt-parent property under /ibm,opal/ipmi DT node on P9
and above, which allows ipmi-opal to properly use the OPAL irqchip.

Signed-off-by: Pridhiviraj Paidipeddi <ppaidipe@linux.vnet.ibm.com>
[stewart: fix indentation]
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

core/ipmi-opal.c

@@ -127,7 +127,7 @@ static int64_t opal_ipmi_recv(uint64_t interface,
 
 void ipmi_opal_init(void)
 {
-	struct dt_node *opal_ipmi;
+	struct dt_node *opal_ipmi, *opal_event = NULL;
 
 	opal_ipmi = dt_new(opal_node, "ipmi");
 	dt_add_property_strings(opal_ipmi, "compatible", "ibm,opal-ipmi");
@@ -136,6 +136,12 @@ void ipmi_opal_init(void)
 	dt_add_property_cells(opal_ipmi, "interrupts",
 			      ilog2(ipmi_backend->opal_event_ipmi_recv));
 
+        if (proc_gen >= proc_gen_p9)
+		opal_event = dt_find_by_name(opal_node, "event");
+	if (opal_event)
+		dt_add_property_cells(opal_ipmi, "interrupt-parent",
+				      opal_event->phandle);
+
 	opal_register(OPAL_IPMI_SEND, opal_ipmi_send, 3);
 	opal_register(OPAL_IPMI_RECV, opal_ipmi_recv, 3);
 }