sysbus: Expose MMIO enumeration helper

Sysbus devices have a range of MMIO regions they expose. The exact number
of regions is device specific and internal information to the device model.

Expose whether a region exists via a public interface. That way our platform
bus enumeration code can dynamically determine how many regions exist.

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

hw/core/sysbus.c

@@ -110,6 +110,12 @@ void sysbus_connect_irq(SysBusDevice *dev, int n, qemu_irq irq)
     qdev_connect_gpio_out_named(DEVICE(dev), SYSBUS_DEVICE_GPIO_IRQ, n, irq);
 }
 
+/* Check whether an MMIO region exists */
+bool sysbus_has_mmio(SysBusDevice *dev, unsigned int n)
+{
+    return (n < dev->num_mmio);
+}
+
 static void sysbus_mmio_map_common(SysBusDevice *dev, int n, hwaddr addr,
                                    bool may_overlap, int priority)
 {

include/hw/sysbus.h

@@ -67,6 +67,7 @@ void sysbus_init_ioports(SysBusDevice *dev, pio_addr_t ioport, pio_addr_t size);
 
 
 bool sysbus_has_irq(SysBusDevice *dev, int n);
+bool sysbus_has_mmio(SysBusDevice *dev, unsigned int n);
 void sysbus_connect_irq(SysBusDevice *dev, int n, qemu_irq irq);
 bool sysbus_is_irq_connected(SysBusDevice *dev, int n);
 qemu_irq sysbus_get_connected_irq(SysBusDevice *dev, int n);