4 files changed, 141 insertions, 0 deletions
diff --git a/hw/misc/Kconfig b/hw/misc/Kconfig
index cb7857e3ed..858277bb60 100644
--- a/hw/misc/Kconfig
+++ b/hw/misc/Kconfig
@@ -189,4 +189,7 @@ config AXP2XX_PMU
 config DJMEMC
     bool
 
+config IOSB
+    bool
+
 source macio/Kconfig
diff --git a/hw/misc/iosb.c b/hw/misc/iosb.c
new file mode 100644
index 0000000000..e7e9dcca47
--- /dev/null
+++ b/hw/misc/iosb.c
@@ -0,0 +1,133 @@
+/*
+ * QEMU IOSB emulation
+ *
+ * Copyright (c) 2019 Laurent Vivier
+ * Copyright (c) 2022 Mark Cave-Ayland
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/log.h"
+#include "migration/vmstate.h"
+#include "hw/sysbus.h"
+#include "hw/misc/iosb.h"
+#include "trace.h"
+
+#define IOSB_SIZE          0x2000
+
+#define IOSB_CONFIG        0x0
+#define IOSB_CONFIG2       0x100
+#define IOSB_SONIC_SCSI    0x200
+#define IOSB_REVISION      0x300
+#define IOSB_SCSI_RESID    0x400
+#define IOSB_BRIGHTNESS    0x500
+#define IOSB_TIMEOUT       0x600
+
+
+static uint64_t iosb_read(void *opaque, hwaddr addr,
+                          unsigned size)
+{
+    IOSBState *s = IOSB(opaque);
+    uint64_t val = 0;
+
+    switch (addr) {
+    case IOSB_CONFIG:
+    case IOSB_CONFIG2:
+    case IOSB_SONIC_SCSI:
+    case IOSB_REVISION:
+    case IOSB_SCSI_RESID:
+    case IOSB_BRIGHTNESS:
+    case IOSB_TIMEOUT:
+        val = s->regs[addr >> 8];
+        break;
+    default:
+        qemu_log_mask(LOG_UNIMP, "IOSB: unimplemented read addr=0x%"PRIx64
+                                 " val=0x%"PRIx64 " size=%d\n",
+                                 addr, val, size);
+    }
+
+    trace_iosb_read(addr, val, size);
+    return val;
+}
+
+static void iosb_write(void *opaque, hwaddr addr, uint64_t val,
+                       unsigned size)
+{
+    IOSBState *s = IOSB(opaque);
+
+    switch (addr) {
+    case IOSB_CONFIG:
+    case IOSB_CONFIG2:
+    case IOSB_SONIC_SCSI:
+    case IOSB_REVISION:
+    case IOSB_SCSI_RESID:
+    case IOSB_BRIGHTNESS:
+    case IOSB_TIMEOUT:
+        s->regs[addr >> 8] = val;
+        break;
+    default:
+        qemu_log_mask(LOG_UNIMP, "IOSB: unimplemented write addr=0x%"PRIx64
+                                 " val=0x%"PRIx64 " size=%d\n",
+                                 addr, val, size);
+    }
+
+    trace_iosb_write(addr, val, size);
+}
+
+static const MemoryRegionOps iosb_mmio_ops = {
+    .read = iosb_read,
+    .write = iosb_write,
+    .endianness = DEVICE_BIG_ENDIAN,
+};
+
+static void iosb_reset_hold(Object *obj)
+{
+    IOSBState *s = IOSB(obj);
+
+    memset(s->regs, 0, sizeof(s->regs));
+
+    /* BCLK 33 MHz */
+    s->regs[IOSB_CONFIG >> 8] = 1;
+}
+
+static void iosb_init(Object *obj)
+{
+    IOSBState *s = IOSB(obj);
+    SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
+
+    memory_region_init_io(&s->mem_regs, obj, &iosb_mmio_ops, s, "IOSB",
+                          IOSB_SIZE);
+    sysbus_init_mmio(sbd, &s->mem_regs);
+}
+
+static const VMStateDescription vmstate_iosb = {
+    .name = "IOSB",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32_ARRAY(regs, IOSBState, IOSB_REGS),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+static void iosb_class_init(ObjectClass *oc, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(oc);
+    ResettableClass *rc = RESETTABLE_CLASS(oc);
+
+    dc->vmsd = &vmstate_iosb;
+    rc->phases.hold = iosb_reset_hold;
+}
+
+static const TypeInfo iosb_info_types[] = {
+    {
+        .name          = TYPE_IOSB,
+        .parent        = TYPE_SYS_BUS_DEVICE,
+        .instance_size = sizeof(IOSBState),
+        .instance_init = iosb_init,
+        .class_init    = iosb_class_init,
+    },
+};
+
+DEFINE_TYPES(iosb_info_types)
diff --git a/hw/misc/meson.build b/hw/misc/meson.build
index ee5ee37648..33659313b4 100644
--- a/hw/misc/meson.build
+++ b/hw/misc/meson.build
@@ -21,6 +21,7 @@ system_ss.add(when: 'CONFIG_ARM_V7M', if_true: files('armv7m_ras.c'))
 # Mac devices
 system_ss.add(when: 'CONFIG_MOS6522', if_true: files('mos6522.c'))
 system_ss.add(when: 'CONFIG_DJMEMC', if_true: files('djmemc.c'))
+system_ss.add(when: 'CONFIG_IOSB', if_true: files('iosb.c'))
 
 # virt devices
 system_ss.add(when: 'CONFIG_VIRT_CTRL', if_true: files('virt_ctrl.c'))
diff --git a/hw/misc/trace-events b/hw/misc/trace-events
index c71a47d288..29bc531d4d 100644
--- a/hw/misc/trace-events
+++ b/hw/misc/trace-events
@@ -305,3 +305,7 @@ lasi_chip_write(uint64_t addr, uint32_t val) "addr 0x%"PRIx64" val 0x%08x"
 # djmemc.c
 djmemc_read(int reg, uint64_t value, unsigned int size) "reg=0x%x value=0x%"PRIx64" size=%u"
 djmemc_write(int reg, uint64_t value, unsigned int size) "reg=0x%x value=0x%"PRIx64" size=%u"
+
+# iosb.c
+iosb_read(int reg, uint64_t value, unsigned int size) "reg=0x%x value=0x%"PRIx64" size=%u"
+iosb_write(int reg, uint64_t value, unsigned int size) "reg=0x%x value=0x%"PRIx64" size=%u"