sysbus: add a variant of sysbus_init_mmio_cb with an unmap callback

sysbus_init_mmio_cb() uses the destructive IO_MEM_UNASSIGNED to remove a
region.  Provide an alternative that calls an unmap callback, so the removal
may be done non-destructively.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

hw/sysbus.c

@@ -53,6 +53,8 @@ void sysbus_mmio_map(SysBusDevice *dev, int n, target_phys_addr_t addr)
         if (dev->mmio[n].memory) {
             memory_region_del_subregion(get_system_memory(),
                                         dev->mmio[n].memory);
+        } else if (dev->mmio[n].unmap) {
+            dev->mmio[n].unmap(dev, dev->mmio[n].addr);
         } else {
             cpu_register_physical_memory(dev->mmio[n].addr, dev->mmio[n].size,
                                          IO_MEM_UNASSIGNED);
@@ -117,6 +119,19 @@ void sysbus_init_mmio_cb(SysBusDevice *dev, target_phys_addr_t size,
     dev->mmio[n].cb = cb;
 }
 
+void sysbus_init_mmio_cb2(SysBusDevice *dev,
+                          mmio_mapfunc cb, mmio_mapfunc unmap)
+{
+    int n;
+
+    assert(dev->num_mmio < QDEV_MAX_MMIO);
+    n = dev->num_mmio++;
+    dev->mmio[n].addr = -1;
+    dev->mmio[n].size = 0;
+    dev->mmio[n].cb = cb;
+    dev->mmio[n].unmap = unmap;
+}
+
 void sysbus_init_mmio_region(SysBusDevice *dev, MemoryRegion *memory)
 {
     int n;

hw/sysbus.h

@@ -23,6 +23,7 @@ struct SysBusDevice {
         target_phys_addr_t addr;
         target_phys_addr_t size;
         mmio_mapfunc cb;
+        mmio_mapfunc unmap;
         ram_addr_t iofunc;
         MemoryRegion *memory;
     } mmio[QDEV_MAX_MMIO];
@@ -48,6 +49,8 @@ void sysbus_init_mmio(SysBusDevice *dev, target_phys_addr_t size,
                       ram_addr_t iofunc);
 void sysbus_init_mmio_cb(SysBusDevice *dev, target_phys_addr_t size,
                             mmio_mapfunc cb);
+void sysbus_init_mmio_cb2(SysBusDevice *dev,
+                          mmio_mapfunc cb, mmio_mapfunc unmap);
 void sysbus_init_mmio_region(SysBusDevice *dev, MemoryRegion *memory);
 void sysbus_init_irq(SysBusDevice *dev, qemu_irq *p);
 void sysbus_pass_irq(SysBusDevice *dev, SysBusDevice *target);