hw/irq: New qemu_init_irq_child() function

The qemu_init_irq() function initializes a TYPE_IRQ QOM object.  The
caller is therefore responsible for eventually calling
qemu_free_irq() to unref (and thus free) it.

In many places where we want to initialize an IRQ we are in
the init/realize of some other QOM object; if we have a variant
of this function that calls object_initialize_child() then the
IRQ will be automatically cleaned up when its parent object is
destroyed, and we don't need to remember to manually free it.

Implement qemu_init_irq_child(), which is to qemu_init_irq()
what object_initialize_child() is to object_initialize().

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250821154053.2417090-2-peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

include/hw/irq.h

@@ -36,11 +36,32 @@ static inline void qemu_irq_pulse(qemu_irq irq)
 
 /*
  * Init a single IRQ. The irq is assigned with a handler, an opaque data
- * and the interrupt number.
+ * and the interrupt number. The caller must free this with qemu_free_irq().
+ * If you are using this inside a device's init or realize method, then
+ * qemu_init_irq_child() is probably a better choice to avoid the need
+ * to manually clean up the IRQ.
  */
 void qemu_init_irq(IRQState *irq, qemu_irq_handler handler, void *opaque,
                    int n);
 
+/**
+ * qemu_init_irq_child: Initialize IRQ and make it a QOM child
+ * @parent: QOM object which owns this IRQ
+ * @propname: child property name
+ * @irq: pointer to IRQState to initialize
+ * @handler: handler function for incoming interrupts
+ * @opaque: opaque data to pass to @handler
+ * @n: interrupt number to pass to @handler
+ *
+ * Init a single IRQ and make the IRQ object a child of @parent with
+ * the child-property name @propname. The IRQ object will thus be
+ * automatically freed when @parent is destroyed.
+ */
+void qemu_init_irq_child(Object *parent, const char *propname,
+                         IRQState *irq, qemu_irq_handler handler,
+                         void *opaque, int n);
+
+
 /**
  * qemu_init_irqs: Initialize an array of IRQs.
  *