hw/core/empty_slot.c

   1 /*
   2  * QEMU Empty Slot
   3  *
   4  * The empty_slot device emulates known to a bus but not connected devices.
   5  *
   6  * Copyright (c) 2010 Artyom Tarasenko
   7  *
   8  * This code is licensed under the GNU GPL v2 or (at your option) any later
   9  * version.
  10  */
  11
  12 #include "hw/hw.h"
  13 #include "hw/sysbus.h"
  14 #include "hw/empty_slot.h"
  15
  16 //#define DEBUG_EMPTY_SLOT
  17
  18 #ifdef DEBUG_EMPTY_SLOT
  19 #define DPRINTF(fmt, ...)                                       \
  20     do { printf("empty_slot: " fmt , ## __VA_ARGS__); } while (0)
  21 #else
  22 #define DPRINTF(fmt, ...) do {} while (0)
  23 #endif
  24
  25 typedef struct EmptySlot {
  26     SysBusDevice busdev;
  27     MemoryRegion iomem;
  28     uint64_t size;
  29 } EmptySlot;
  30
  31 static uint64_t empty_slot_read(void *opaque, hwaddr addr,
  32                                 unsigned size)
  33 {
  34     DPRINTF("read from " TARGET_FMT_plx "\n", addr);
  35     return 0;
  36 }
  37
  38 static void empty_slot_write(void *opaque, hwaddr addr,
  39                              uint64_t val, unsigned size)
  40 {
  41     DPRINTF("write 0x%x to " TARGET_FMT_plx "\n", (unsigned)val, addr);
  42 }
  43
  44 static const MemoryRegionOps empty_slot_ops = {
  45     .read = empty_slot_read,
  46     .write = empty_slot_write,
  47     .endianness = DEVICE_NATIVE_ENDIAN,
  48 };
  49
  50 void empty_slot_init(hwaddr addr, uint64_t slot_size)
  51 {
  52     if (slot_size > 0) {
  53         /* Only empty slots larger than 0 byte need handling. */
  54         DeviceState *dev;
  55         SysBusDevice *s;
  56         EmptySlot *e;
  57
  58         dev = qdev_create(NULL, "empty_slot");
  59         s = SYS_BUS_DEVICE(dev);
  60         e = FROM_SYSBUS(EmptySlot, s);
  61         e->size = slot_size;
  62
  63         qdev_init_nofail(dev);
  64
  65         sysbus_mmio_map(s, 0, addr);
  66     }
  67 }
  68
  69 static int empty_slot_init1(SysBusDevice *dev)
  70 {
  71     EmptySlot *s = FROM_SYSBUS(EmptySlot, dev);
  72
  73     memory_region_init_io(&s->iomem, NULL, &empty_slot_ops, s,
  74                           "empty-slot", s->size);
  75     sysbus_init_mmio(dev, &s->iomem);
  76     return 0;
  77 }
  78
  79 static void empty_slot_class_init(ObjectClass *klass, void *data)
  80 {
  81     SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
  82
  83     k->init = empty_slot_init1;
  84 }
  85
  86 static const TypeInfo empty_slot_info = {
  87     .name          = "empty_slot",
  88     .parent        = TYPE_SYS_BUS_DEVICE,
  89     .instance_size = sizeof(EmptySlot),
  90     .class_init    = empty_slot_class_init,
  91 };
  92
  93 static void empty_slot_register_types(void)
  94 {
  95     type_register_static(&empty_slot_info);
  96 }
  97
  98 type_init(empty_slot_register_types)