irqchip: gic: Use mask field in GICC_IAR

Bit[9:0] is interrupt ID field in GICC_IAR. Bit[12:10] is CPU ID field,
and others are reserved.

So we should use GICC_IAR_INT_ID_MASK to get interrupt ID. It's not a good way
to use ~0x1c00 (CPU ID field) to get interrupt ID.
Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Link: https://lkml.kernel.org/r/1399795571-17231-3-git-send-email-haojian.zhuang@linaro.orgSigned-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/irqchip/irq-gic.c

@@ -287,7 +287,7 @@ static void __exception_irq_entry gic_handle_irq(struct pt_regs *regs)
 
 	do {
 		irqstat = readl_relaxed(cpu_base + GIC_CPU_INTACK);
-		irqnr = irqstat & ~0x1c00;
+		irqnr = irqstat & GICC_IAR_INT_ID_MASK;
 
 		if (likely(irqnr > 15 && irqnr < 1021)) {
 			irqnr = irq_find_mapping(gic->domain, irqnr);

include/linux/irqchip/arm-gic.h

@@ -21,6 +21,8 @@
 #define GIC_CPU_ACTIVEPRIO		0xd0
 #define GIC_CPU_IDENT			0xfc
 
+#define GICC_IAR_INT_ID_MASK		0x3ff
+
 #define GIC_DIST_CTRL			0x000
 #define GIC_DIST_CTR			0x004
 #define GIC_DIST_IGROUP			0x080