irqchip: GICv3: ITS: MSI support

Now, the bit of code that allow us to use the ITS as a MSI controller.
Both MSI and MSI-X are supported.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1416839720-18400-10-git-send-email-marc.zyngier@arm.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

include/linux/irqchip/arm-gic-v3.h

@@ -295,6 +295,12 @@
 
 #include <linux/stringify.h>
 
+/*
+ * We need a value to serve as a irq-type for LPIs. Choose one that will
+ * hopefully pique the interest of the reviewer.
+ */
+#define GIC_IRQ_TYPE_LPI		0xa110c8ed
+
 struct rdists {
 	struct {
 		void __iomem	*rd_base;