qemu/hw/i386/port92.c

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/*
* QEMU I/O port 0x92 (System Control Port A, to handle Fast Gate A20)
*
* Copyright (c) 2003-2004 Fabrice Bellard
*
* SPDX-License-Identifier: MIT
*/
#include "qemu/osdep.h"
#include "sysemu/runstate.h"
#include "migration/vmstate.h"
#include "hw/irq.h"
#include "hw/i386/pc.h"
#include "trace.h"
#include "qom/object.h"
OBJECT_DECLARE_SIMPLE_TYPE(Port92State, PORT92)
struct Port92State {
ISADevice parent_obj;
MemoryRegion io;
uint8_t outport;
qemu_irq a20_out;
};
static void port92_write(void *opaque, hwaddr addr, uint64_t val,
unsigned size)
{
Port92State *s = opaque;
int oldval = s->outport;
trace_port92_write(val);
s->outport = val;
qemu_set_irq(s->a20_out, (val >> 1) & 1);
if ((val & 1) && !(oldval & 1)) {
qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
}
}
static uint64_t port92_read(void *opaque, hwaddr addr,
unsigned size)
{
Port92State *s = opaque;
uint32_t ret;
ret = s->outport;
trace_port92_read(ret);
return ret;
}
static const VMStateDescription vmstate_port92_isa = {
.name = "port92",
.version_id = 1,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_UINT8(outport, Port92State),
VMSTATE_END_OF_LIST()
}
};
static void port92_reset(DeviceState *d)
{
Port92State *s = PORT92(d);
s->outport &= ~1;
}
static const MemoryRegionOps port92_ops = {
.read = port92_read,
.write = port92_write,
.impl = {
.min_access_size = 1,
.max_access_size = 1,
},
.endianness = DEVICE_LITTLE_ENDIAN,
};
static void port92_initfn(Object *obj)
{
Port92State *s = PORT92(obj);
memory_region_init_io(&s->io, OBJECT(s), &port92_ops, s, "port92", 1);
s->outport = 0;
qdev_init_gpio_out_named(DEVICE(obj), &s->a20_out, PORT92_A20_LINE, 1);
}
static void port92_realizefn(DeviceState *dev, Error **errp)
{
ISADevice *isadev = ISA_DEVICE(dev);
Port92State *s = PORT92(dev);
isa_register_ioport(isadev, &s->io, 0x92);
}
static void port92_class_initfn(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->realize = port92_realizefn;
dc->reset = port92_reset;
dc->vmsd = &vmstate_port92_isa;
/*
* Reason: unlike ordinary ISA devices, this one needs additional
* wiring: its A20 output line needs to be wired up with
* qdev_connect_gpio_out_named().
*/
dc->user_creatable = false;
}
static const TypeInfo port92_info = {
.name = TYPE_PORT92,
.parent = TYPE_ISA_DEVICE,
.instance_size = sizeof(Port92State),
.instance_init = port92_initfn,
.class_init = port92_class_initfn,
};
static void port92_register_types(void)
{
type_register_static(&port92_info);
}
type_init(port92_register_types)