sysbus: Expose IRQ enumeration helpers

Sysbus devices can get their IRQ lines connected to other devices. It is
possible to figure out which IRQ line a connection is on and whether a sysbus
device even provides an IRQ connector at a specific offset.

This patch exposes helpers to make this information publicly accessible. We
will need it for the platform bus dynamic sysbus enumeration.

Signed-off-by: Alexander Graf <agraf@suse.de>

hw/core/qdev.c

@@ -453,6 +453,17 @@ void qdev_connect_gpio_out_named(DeviceState *dev, const char *name, int n,
     g_free(propname);
 }
 
+qemu_irq qdev_get_gpio_out_connector(DeviceState *dev, const char *name, int n)
+{
+    char *propname = g_strdup_printf("%s[%d]",
+                                     name ? name : "unnamed-gpio-out", n);
+
+    qemu_irq ret = (qemu_irq)object_property_get_link(OBJECT(dev), propname,
+                                                      NULL);
+
+    return ret;
+}
+
 /* disconnect a GPIO ouput, returning the disconnected input (if any) */
 
 static qemu_irq qdev_disconnect_gpio_out_named(DeviceState *dev,