qemu/hw/misc/unimp.c

/* "Unimplemented" device
 *
 * This is a dummy device which accepts and logs all accesses.
 * It's useful for stubbing out regions of an SoC or board
 * map which correspond to devices that have not yet been
 * implemented. This is often sufficient to placate initial
 * guest device driver probing such that the system will
 * come up.
 *
 * Copyright Linaro Limited, 2017
 * Written by Peter Maydell
 */

#include "qemu/osdep.h"
#include "hw/hw.h"
#include "hw/sysbus.h"
#include "hw/misc/unimp.h"
#include "qemu/log.h"
#include "qapi/error.h"

#define UNIMPLEMENTED_DEVICE(obj) \
    OBJECT_CHECK(UnimplementedDeviceState, (obj), TYPE_UNIMPLEMENTED_DEVICE)

typedef struct {
    SysBusDevice parent_obj;
    MemoryRegion iomem;
    char *name;
    uint64_t size;
} UnimplementedDeviceState;

static uint64_t unimp_read(void *opaque, hwaddr offset, unsigned size)
{
    UnimplementedDeviceState *s = UNIMPLEMENTED_DEVICE(opaque);

    qemu_log_mask(LOG_UNIMP, "%s: unimplemented device read "
                  "(size %d, offset 0x%" HWADDR_PRIx ")\n",
                  s->name, size, offset);
    return 0;
}

static void unimp_write(void *opaque, hwaddr offset,
                        uint64_t value, unsigned size)
{
    UnimplementedDeviceState *s = UNIMPLEMENTED_DEVICE(opaque);

    qemu_log_mask(LOG_UNIMP, "%s: unimplemented device write "
                  "(size %d, value 0x%" PRIx64
                  ", offset 0x%" HWADDR_PRIx ")\n",
                  s->name, size, value, offset);
}

static const MemoryRegionOps unimp_ops = {
    .read = unimp_read,
    .write = unimp_write,
    .impl.min_access_size = 1,
    .impl.max_access_size = 8,
    .valid.min_access_size = 1,
    .valid.max_access_size = 8,
    .endianness = DEVICE_NATIVE_ENDIAN,
};

static void unimp_realize(DeviceState *dev, Error **errp)
{
    UnimplementedDeviceState *s = UNIMPLEMENTED_DEVICE(dev);

    if (s->size == 0) {
        error_setg(errp, "property 'size' not specified or zero");
        return;
    }

    if (s->name == NULL) {
        error_setg(errp, "property 'name' not specified");
        return;
    }

    memory_region_init_io(&s->iomem, OBJECT(s), &unimp_ops, s,
                          s->name, s->size);
    sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->iomem);
}

static Property unimp_properties[] = {
    DEFINE_PROP_UINT64("size", UnimplementedDeviceState, size, 0),
    DEFINE_PROP_STRING("name", UnimplementedDeviceState, name),
    DEFINE_PROP_END_OF_LIST(),
};

static void unimp_class_init(ObjectClass *klass, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);

    dc->realize = unimp_realize;
    dc->props = unimp_properties;
    /*
     * FIXME: Set only because we are not sure yet if this device
     * will be outside the q35 sysbus whitelist.
     */
    dc->user_creatable = true;
}

static const TypeInfo unimp_info = {
    .name = TYPE_UNIMPLEMENTED_DEVICE,
    .parent = TYPE_SYS_BUS_DEVICE,
    .instance_size = sizeof(UnimplementedDeviceState),
    .class_init = unimp_class_init,
};

static void unimp_register_types(void)
{
    type_register_static(&unimp_info);
}

type_init(unimp_register_types)