allwinner-a10-pic: set vector address when an interrupt is pending

This patch implements proper updating of the vector register which
should hold, according to the A10 user manual, the vector address for
the interrupt currently active on the CPU IRQ input.

Interrupt priority is not implemented at the moment and thus the first
pending interrupt is returned.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Reviewed-by: Li Guang <lig.fnst@cn.fujitsu.com>
Message-id: 1395771730-16882-2-git-send-email-b.galvani@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/intc/allwinner-a10-pic.c

@@ -23,11 +23,20 @@
 static void aw_a10_pic_update(AwA10PICState *s)
 {
     uint8_t i;
-    int irq = 0, fiq = 0;
+    int irq = 0, fiq = 0, pending;
+
+    s->vector = 0;
 
     for (i = 0; i < AW_A10_PIC_REG_NUM; i++) {
         irq |= s->irq_pending[i] & ~s->mask[i];
         fiq |= s->select[i] & s->irq_pending[i] & ~s->mask[i];
+
+        if (!s->vector) {
+            pending = ffs(s->irq_pending[i] & ~s->mask[i]);
+            if (pending) {
+                s->vector = (i * 32 + pending - 1) * 4;
+            }
+        }
     }
 
     qemu_set_irq(s->parent_irq, !!irq);
@@ -84,9 +93,6 @@ static void aw_a10_pic_write(void *opaque, hwaddr offset, uint64_t value,
     uint8_t index = (offset & 0xc) / 4;
 
     switch (offset) {
-    case AW_A10_PIC_VECTOR:
-        s->vector = value & ~0x3;
-        break;
     case AW_A10_PIC_BASE_ADDR:
         s->base_addr = value & ~0x3;
     case AW_A10_PIC_PROTECT: