allwinner-a10-pic: fix behaviour of pending register

The pending register is read-only and the value returned upon a read
reflects the state of irq input pins (interrupts are level triggered).
This patch implements such behaviour.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Reviewed-by: Li Guang <lig.fnst@cn.fujitsu.com>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: 1395771730-16882-3-git-send-email-b.galvani@gmail.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/hw/intc/allwinner-a10-pic.c b/hw/intc/allwinner-a10-pic.c
index 00f3c11..0924d98 100644
--- a/hw/intc/allwinner-a10-pic.c
+++ b/hw/intc/allwinner-a10-pic.c
@@ -49,6 +49,8 @@ static void aw_a10_pic_set_irq(void *opaque, int irq, int level)
 
     if (level) {
         set_bit(irq % 32, (void *)&s->irq_pending[irq / 32]);
+    } else {
+        clear_bit(irq % 32, (void *)&s->irq_pending[irq / 32]);
     }
     aw_a10_pic_update(s);
 }
@@ -102,7 +104,11 @@ static void aw_a10_pic_write(void *opaque, hwaddr offset, uint64_t value,
         s->nmi = value;
         break;
     case AW_A10_PIC_IRQ_PENDING ... AW_A10_PIC_IRQ_PENDING + 8:
-        s->irq_pending[index] &= ~value;
+        /*
+         * The register is read-only; nevertheless, Linux (including
+         * the version originally shipped by Allwinner) pretends to
+         * write to the register. Just ignore it.
+         */
         break;
     case AW_A10_PIC_FIQ_PENDING ... AW_A10_PIC_FIQ_PENDING + 8:
         s->fiq_pending[index] &= ~value;