nubus: use bitmap to manage available slots

Convert nubus_device_realize() to use a bitmap to manage available slots to allow
for future Nubus devices to be plugged into arbitrary slots from the command line
using a new qdev "slot" parameter for nubus devices.

Update mac_nubus_bridge_init() to only allow slots 0x9 to 0xe on Macintosh machines
as documented in "Designing Cards and Drivers for the Macintosh Family".

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: <20210924073808.1041-5-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

3 files changed, 31 insertions, 7 deletions

diff --git a/hw/nubus/mac-nubus-bridge.c b/hw/nubus/mac-nubus-bridge.c
index 7c329300b8..3f075789e9 100644
--- a/hw/nubus/mac-nubus-bridge.c
+++ b/hw/nubus/mac-nubus-bridge.c
@@ -18,6 +18,10 @@ static void mac_nubus_bridge_init(Object *obj)
 
     s->bus = NUBUS_BUS(qbus_create(TYPE_NUBUS_BUS, DEVICE(s), NULL));
 
+    /* Macintosh only has slots 0x9 to 0xe available */
+    s->bus->slot_available_mask = MAKE_64BIT_MASK(MAC_NUBUS_FIRST_SLOT,
+                                                  MAC_NUBUS_SLOT_NB);
+
     sysbus_init_mmio(sbd, &s->bus->super_slot_io);
     sysbus_init_mmio(sbd, &s->bus->slot_io);
 }
diff --git a/hw/nubus/nubus-bus.c b/hw/nubus/nubus-bus.c
index f4410803ff..3cd7534864 100644
--- a/hw/nubus/nubus-bus.c
+++ b/hw/nubus/nubus-bus.c
@@ -86,13 +86,14 @@ static void nubus_init(Object *obj)
 
     memory_region_init_io(&nubus->super_slot_io, obj, &nubus_super_slot_ops,
                           nubus, "nubus-super-slots",
-                          NUBUS_SUPER_SLOT_NB * NUBUS_SUPER_SLOT_SIZE);
+                          (NUBUS_SUPER_SLOT_NB + 1) * NUBUS_SUPER_SLOT_SIZE);
 
     memory_region_init_io(&nubus->slot_io, obj, &nubus_slot_ops,
                           nubus, "nubus-slots",
                           NUBUS_SLOT_NB * NUBUS_SLOT_SIZE);
 
-    nubus->current_slot = NUBUS_FIRST_SLOT;
+    nubus->slot_available_mask = MAKE_64BIT_MASK(NUBUS_FIRST_SLOT,
+                                                 NUBUS_SLOT_NB);
 }
 
 static void nubus_class_init(ObjectClass *oc, void *data)
diff --git a/hw/nubus/nubus-device.c b/hw/nubus/nubus-device.c
index 4e23df1280..2e96d6b4fc 100644
--- a/hw/nubus/nubus-device.c
+++ b/hw/nubus/nubus-device.c
@@ -161,13 +161,26 @@ static void nubus_device_realize(DeviceState *dev, Error **errp)
     char *name;
     hwaddr slot_offset;
 
-    if (nubus->current_slot < NUBUS_FIRST_SLOT ||
-            nubus->current_slot > NUBUS_LAST_SLOT) {
-        error_setg(errp, "Cannot register nubus card, not enough slots");
-        return;
+    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;
+        }
+    } 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;
+        }
     }
 
-    nd->slot = nubus->current_slot++;
+    nubus->slot_available_mask &= ~BIT(nd->slot);
 
     /* Super */
     slot_offset = nd->slot * NUBUS_SUPER_SLOT_SIZE;
@@ -191,12 +204,18 @@ static void nubus_device_realize(DeviceState *dev, Error **errp)
     nubus_register_format_block(nd);
 }
 
+static Property nubus_device_properties[] = {
+    DEFINE_PROP_INT32("slot", NubusDevice, slot, -1),
+    DEFINE_PROP_END_OF_LIST()
+};
+
 static void nubus_device_class_init(ObjectClass *oc, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(oc);
 
     dc->realize = nubus_device_realize;
     dc->bus_type = TYPE_NUBUS_BUS;
+    device_class_set_props(dc, nubus_device_properties);
 }
 
 static const TypeInfo nubus_device_type_info = {