qemu/hw/empty_slot.c

/*
 * QEMU Empty Slot
 *
 * The empty_slot device emulates known to a bus but not connected devices.
 *
 * Copyright (c) 2010 Artyom Tarasenko
 *
 * This code is licensed under the GNU GPL v2 or (at your option) any later
 * version.
 */

#include "hw.h"
#include "sysbus.h"
#include "empty_slot.h"

//#define DEBUG_EMPTY_SLOT

#ifdef DEBUG_EMPTY_SLOT
#define DPRINTF(fmt, ...)                                       \
    do { printf("empty_slot: " fmt , ## __VA_ARGS__); } while (0)
#else
#define DPRINTF(fmt, ...) do {} while (0)
#endif

typedef struct EmptySlot {
    SysBusDevice busdev;
    MemoryRegion iomem;
    uint64_t size;
} EmptySlot;

static uint64_t empty_slot_read(void *opaque, target_phys_addr_t addr,
                                unsigned size)
{
    DPRINTF("read from " TARGET_FMT_plx "\n", addr);
    return 0;
}

static void empty_slot_write(void *opaque, target_phys_addr_t addr,
                             uint64_t val, unsigned size)
{
    DPRINTF("write 0x%x to " TARGET_FMT_plx "\n", (unsigned)val, addr);
}

static const MemoryRegionOps empty_slot_ops = {
    .read = empty_slot_read,
    .write = empty_slot_write,
    .endianness = DEVICE_NATIVE_ENDIAN,
};

void empty_slot_init(target_phys_addr_t addr, uint64_t slot_size)
{
    if (slot_size > 0) {
        /* Only empty slots larger than 0 byte need handling. */
        DeviceState *dev;
        SysBusDevice *s;
        EmptySlot *e;

        dev = qdev_create(NULL, "empty_slot");
        s = sysbus_from_qdev(dev);
        e = FROM_SYSBUS(EmptySlot, s);
        e->size = slot_size;

        qdev_init_nofail(dev);

        sysbus_mmio_map(s, 0, addr);
    }
}

static int empty_slot_init1(SysBusDevice *dev)
{
    EmptySlot *s = FROM_SYSBUS(EmptySlot, dev);

    memory_region_init_io(&s->iomem, &empty_slot_ops, s,
                          "empty-slot", s->size);
    sysbus_init_mmio(dev, &s->iomem);
    return 0;
}

static SysBusDeviceInfo empty_slot_info = {
    .init = empty_slot_init1,
    .qdev.name  = "empty_slot",
    .qdev.size  = sizeof(EmptySlot),
};

static void empty_slot_register_devices(void)
{
    sysbus_register_withprop(&empty_slot_info);
}

device_init(empty_slot_register_devices);