nubus: move nubus to its own 32-bit address space

According to "Designing Cards and Drivers for the Macintosh Family" the Nubus
has its own 32-bit address space based upon physical slot addressing.

Move Nubus to its own 32-bit address space and then use memory region aliases
to map available slot and super slot ranges into the q800 system address
space via the Macintosh Nubus bridge.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20210924073808.1041-13-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

hw/m68k/q800.c

@@ -67,9 +67,6 @@
 #define ASC_BASE              (IO_BASE + 0x14000)
 #define SWIM_BASE             (IO_BASE + 0x1E000)
 
-#define NUBUS_SUPER_SLOT_BASE 0x60000000
-#define NUBUS_SLOT_BASE       0xf0000000
-
 #define SONIC_PROM_SIZE       0x1000
 
 /*
@@ -396,8 +393,10 @@ static void q800_init(MachineState *machine)
 
     dev = qdev_new(TYPE_MAC_NUBUS_BRIDGE);
     sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
-    sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0, NUBUS_SUPER_SLOT_BASE);
-    sysbus_mmio_map(SYS_BUS_DEVICE(dev), 1, NUBUS_SLOT_BASE);
+    sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0,
+                    MAC_NUBUS_FIRST_SLOT * NUBUS_SUPER_SLOT_SIZE);
+    sysbus_mmio_map(SYS_BUS_DEVICE(dev), 1, NUBUS_SLOT_BASE +
+                    MAC_NUBUS_FIRST_SLOT * NUBUS_SLOT_SIZE);
 
     nubus = MAC_NUBUS_BRIDGE(dev)->bus;
 

hw/nubus/mac-nubus-bridge.c

@@ -22,8 +22,20 @@ static void mac_nubus_bridge_init(Object *obj)
     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);
+    /* Aliases for slots 0x9 to 0xe */
+    memory_region_init_alias(&s->super_slot_alias, obj, "super-slot-alias",
+                             &s->bus->nubus_mr,
+                             MAC_NUBUS_FIRST_SLOT * NUBUS_SUPER_SLOT_SIZE,
+                             MAC_NUBUS_SLOT_NB * NUBUS_SUPER_SLOT_SIZE);
+
+    memory_region_init_alias(&s->slot_alias, obj, "slot-alias",
+                             &s->bus->nubus_mr,
+                             NUBUS_SLOT_BASE +
+                             MAC_NUBUS_FIRST_SLOT * NUBUS_SLOT_SIZE,
+                             MAC_NUBUS_SLOT_NB * NUBUS_SLOT_SIZE);
+
+    sysbus_init_mmio(sbd, &s->super_slot_alias);
+    sysbus_init_mmio(sbd, &s->slot_alias);
 }
 
 static void mac_nubus_bridge_class_init(ObjectClass *klass, void *data)

hw/nubus/nubus-bus.c

@@ -78,25 +78,42 @@ static const MemoryRegionOps nubus_super_slot_ops = {
     },
 };
 
+static void nubus_unrealize(BusState *bus)
+{
+    NubusBus *nubus = NUBUS_BUS(bus);
+
+    address_space_destroy(&nubus->nubus_as);
+}
+
 static void nubus_realize(BusState *bus, Error **errp)
 {
+    NubusBus *nubus = NUBUS_BUS(bus);
+
     if (!nubus_find()) {
         error_setg(errp, "at most one %s device is permitted", TYPE_NUBUS_BUS);
         return;
     }
+
+    address_space_init(&nubus->nubus_as, &nubus->nubus_mr, "nubus");
 }
 
 static void nubus_init(Object *obj)
 {
     NubusBus *nubus = NUBUS_BUS(obj);
 
+    memory_region_init(&nubus->nubus_mr, obj, "nubus", 0x100000000);
+
     memory_region_init_io(&nubus->super_slot_io, obj, &nubus_super_slot_ops,
                           nubus, "nubus-super-slots",
                           (NUBUS_SUPER_SLOT_NB + 1) * NUBUS_SUPER_SLOT_SIZE);
+    memory_region_add_subregion(&nubus->nubus_mr, 0x0, &nubus->super_slot_io);
 
     memory_region_init_io(&nubus->slot_io, obj, &nubus_slot_ops,
                           nubus, "nubus-slots",
                           NUBUS_SLOT_NB * NUBUS_SLOT_SIZE);
+    memory_region_add_subregion(&nubus->nubus_mr,
+                                (NUBUS_SUPER_SLOT_NB + 1) *
+                                NUBUS_SUPER_SLOT_SIZE, &nubus->slot_io);
 
     nubus->slot_available_mask = MAKE_64BIT_MASK(NUBUS_FIRST_SLOT,
                                                  NUBUS_SLOT_NB);
@@ -150,6 +167,7 @@ static void nubus_class_init(ObjectClass *oc, void *data)
     BusClass *bc = BUS_CLASS(oc);
 
     bc->realize = nubus_realize;
+    bc->unrealize = nubus_unrealize;
     bc->check_address = nubus_check_address;
     bc->get_dev_path = nubus_get_dev_path;
 }

include/hw/nubus/mac-nubus-bridge.h

@@ -23,6 +23,8 @@ struct MacNubusState {
     SysBusDevice sysbus_dev;
 
     NubusBus *bus;
+    MemoryRegion super_slot_alias;
+    MemoryRegion slot_alias;
 };
 
 #endif

include/hw/nubus/nubus.h

@@ -17,6 +17,9 @@
 #define NUBUS_SUPER_SLOT_SIZE 0x10000000U
 #define NUBUS_SUPER_SLOT_NB   0xe
 
+#define NUBUS_SLOT_BASE       (NUBUS_SUPER_SLOT_SIZE * \
+                               (NUBUS_SUPER_SLOT_NB + 1))
+
 #define NUBUS_SLOT_SIZE       0x01000000
 #define NUBUS_FIRST_SLOT      0x0
 #define NUBUS_LAST_SLOT       0xf
@@ -33,6 +36,9 @@ OBJECT_DECLARE_SIMPLE_TYPE(NubusBus, NUBUS_BUS)
 struct NubusBus {
     BusState qbus;
 
+    AddressSpace nubus_as;
+    MemoryRegion nubus_mr;
+
     MemoryRegion super_slot_io;
     MemoryRegion slot_io;