hw/irq: Add qemu_irq_split() so one GPIO output can feed two inputs

Add a qemu_irq_split() function which allows a board to wire a single
GPIO output up to two GPIO inputs. This is needed for realview boards,
where the MMC card status is visible both in a system register and
via a PL061 GPIO module.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

2 files changed, 18 insertions, 0 deletions

diff --git a/hw/irq.c b/hw/irq.c
index 7703f62c6c..4035a8cbff 100644
--- a/hw/irq.c
+++ b/hw/irq.c
@@ -75,3 +75,18 @@ qemu_irq qemu_irq_invert(qemu_irq irq)
     qemu_irq_raise(irq);
     return qemu_allocate_irqs(qemu_notirq, irq, 1)[0];
 }
+
+static void qemu_splitirq(void *opaque, int line, int level)
+{
+    struct IRQState **irq = opaque;
+    irq[0]->handler(irq[0]->opaque, irq[0]->n, level);
+    irq[1]->handler(irq[1]->opaque, irq[1]->n, level);
+}
+
+qemu_irq qemu_irq_split(qemu_irq irq1, qemu_irq irq2)
+{
+    qemu_irq *s = qemu_mallocz(2 * sizeof(qemu_irq));
+    s[0] = irq1;
+    s[1] = irq2;
+    return qemu_allocate_irqs(qemu_splitirq, s, 1)[0];
+}
diff --git a/hw/irq.h b/hw/irq.h
index f7849edc8e..389ed7a506 100644
--- a/hw/irq.h
+++ b/hw/irq.h
@@ -30,4 +30,7 @@ void qemu_free_irqs(qemu_irq *s);
 /* Returns a new IRQ with opposite polarity.  */
 qemu_irq qemu_irq_invert(qemu_irq irq);
 
+/* Returns a new IRQ which feeds into both the passed IRQs */
+qemu_irq qemu_irq_split(qemu_irq irq1, qemu_irq irq2);
+
 #endif