qdev: gpio: Add API for intercepting a GPIO

To replace the old qemu_irq intercept API (which had users reaching
into qdev private state for GPIOs).

Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/core/qdev.c

@@ -455,6 +455,31 @@ void qdev_connect_gpio_out_named(DeviceState *dev, const char *name, int n,
     g_free(propname);
 }
 
+/* disconnect a GPIO ouput, returning the disconnected input (if any) */
+
+static qemu_irq qdev_disconnect_gpio_out_named(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);
+    if (ret) {
+        object_property_set_link(OBJECT(dev), NULL, propname, NULL);
+    }
+    g_free(propname);
+    return ret;
+}
+
+qemu_irq qdev_intercept_gpio_out(DeviceState *dev, qemu_irq icpt,
+                                 const char *name, int n)
+{
+    qemu_irq disconnected = qdev_disconnect_gpio_out_named(dev, name, n);
+    qdev_connect_gpio_out_named(dev, name, n, icpt);
+    return disconnected;
+}
+
 void qdev_connect_gpio_out(DeviceState * dev, int n, qemu_irq pin)
 {
     qdev_connect_gpio_out_named(dev, NULL, n, pin);

include/hw/qdev-core.h

@@ -273,6 +273,8 @@ qemu_irq qdev_get_gpio_in_named(DeviceState *dev, const char *name, int n);
 void qdev_connect_gpio_out(DeviceState *dev, int n, qemu_irq pin);
 void qdev_connect_gpio_out_named(DeviceState *dev, const char *name, int n,
                                  qemu_irq pin);
+qemu_irq qdev_intercept_gpio_out(DeviceState *dev, qemu_irq icpt,
+                                 const char *name, int n);
 
 BusState *qdev_get_child_bus(DeviceState *dev, const char *name);