nubus: move slot bitmap checks from NubusDevice realize() to BusClass check_address()

Allow Nubus to manage the slot allocations itself using the BusClass check_address()
virtual function rather than managing this during NubusDevice realize().

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20210924073808.1041-6-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

1 files changed, 29 insertions, 0 deletions

diff --git a/hw/nubus/nubus-bus.c b/hw/nubus/nubus-bus.c
index 3cd7534..96ef027 100644
--- a/hw/nubus/nubus-bus.c
+++ b/hw/nubus/nubus-bus.c
@@ -96,11 +96,40 @@ static void nubus_init(Object *obj)
                                                  NUBUS_SLOT_NB);
 }
 
+static bool nubus_check_address(BusState *bus, DeviceState *dev, Error **errp)
+{
+    NubusDevice *nd = NUBUS_DEVICE(dev);
+    NubusBus *nubus = NUBUS_BUS(bus);
+
+    if (nd->slot == -1) {
+        /* No slot specified, find first available free slot */
+        int s = ctz32(nubus->slot_available_mask);
+        if (s != 32) {
+            nd->slot = s;
+        } else {
+            error_setg(errp, "Cannot register nubus card, no free slot "
+                             "available");
+            return false;
+        }
+    } else {
+        /* Slot specified, make sure the slot is available */
+        if (!(nubus->slot_available_mask & BIT(nd->slot))) {
+            error_setg(errp, "Cannot register nubus card, slot %d is "
+                             "unavailable or already occupied", nd->slot);
+            return false;
+        }
+    }
+
+    nubus->slot_available_mask &= ~BIT(nd->slot);
+    return true;
+}
+
 static void nubus_class_init(ObjectClass *oc, void *data)
 {
     BusClass *bc = BUS_CLASS(oc);
 
     bc->realize = nubus_realize;
+    bc->check_address = nubus_check_address;
 }
 
 static const TypeInfo nubus_bus_info = {