hw/i386/port92.c

   1 /*
   2  * QEMU I/O port 0x92 (System Control Port A, to handle Fast Gate A20)
   3  *
   4  * Copyright (c) 2003-2004 Fabrice Bellard
   5  *
   6  * SPDX-License-Identifier: MIT
   7  */
   8
   9 #include "qemu/osdep.h"
  10 #include "sysemu/runstate.h"
  11 #include "migration/vmstate.h"
  12 #include "hw/irq.h"
  13 #include "hw/i386/pc.h"
  14 #include "trace.h"
  15 #include "qom/object.h"
  16
  17 OBJECT_DECLARE_SIMPLE_TYPE(Port92State, PORT92)
  18
  19 struct Port92State {
  20     ISADevice parent_obj;
  21
  22     MemoryRegion io;
  23     uint8_t outport;
  24     qemu_irq a20_out;
  25 };
  26
  27 static void port92_write(void *opaque, hwaddr addr, uint64_t val,
  28                          unsigned size)
  29 {
  30     Port92State *s = opaque;
  31     int oldval = s->outport;
  32
  33     trace_port92_write(val);
  34     s->outport = val;
  35     qemu_set_irq(s->a20_out, (val >> 1) & 1);
  36     if ((val & 1) && !(oldval & 1)) {
  37         qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
  38     }
  39 }
  40
  41 static uint64_t port92_read(void *opaque, hwaddr addr,
  42                             unsigned size)
  43 {
  44     Port92State *s = opaque;
  45     uint32_t ret;
  46
  47     ret = s->outport;
  48     trace_port92_read(ret);
  49
  50     return ret;
  51 }
  52
  53 static const VMStateDescription vmstate_port92_isa = {
  54     .name = "port92",
  55     .version_id = 1,
  56     .minimum_version_id = 1,
  57     .fields = (VMStateField[]) {
  58         VMSTATE_UINT8(outport, Port92State),
  59         VMSTATE_END_OF_LIST()
  60     }
  61 };
  62
  63 static void port92_reset(DeviceState *d)
  64 {
  65     Port92State *s = PORT92(d);
  66
  67     s->outport &= ~1;
  68 }
  69
  70 static const MemoryRegionOps port92_ops = {
  71     .read = port92_read,
  72     .write = port92_write,
  73     .impl = {
  74         .min_access_size = 1,
  75         .max_access_size = 1,
  76     },
  77     .endianness = DEVICE_LITTLE_ENDIAN,
  78 };
  79
  80 static void port92_initfn(Object *obj)
  81 {
  82     Port92State *s = PORT92(obj);
  83
  84     memory_region_init_io(&s->io, OBJECT(s), &port92_ops, s, "port92", 1);
  85
  86     s->outport = 0;
  87
  88     qdev_init_gpio_out_named(DEVICE(obj), &s->a20_out, PORT92_A20_LINE, 1);
  89 }
  90
  91 static void port92_realizefn(DeviceState *dev, Error **errp)
  92 {
  93     ISADevice *isadev = ISA_DEVICE(dev);
  94     Port92State *s = PORT92(dev);
  95
  96     isa_register_ioport(isadev, &s->io, 0x92);
  97 }
  98
  99 static void port92_class_initfn(ObjectClass *klass, void *data)
 100 {
 101     DeviceClass *dc = DEVICE_CLASS(klass);
 102
 103     dc->realize = port92_realizefn;
 104     dc->reset = port92_reset;
 105     dc->vmsd = &vmstate_port92_isa;
 106     /*
 107      * Reason: unlike ordinary ISA devices, this one needs additional
 108      * wiring: its A20 output line needs to be wired up with
 109      * qdev_connect_gpio_out_named().
 110      */
 111     dc->user_creatable = false;
 112 }
 113
 114 static const TypeInfo port92_info = {
 115     .name          = TYPE_PORT92,
 116     .parent        = TYPE_ISA_DEVICE,
 117     .instance_size = sizeof(Port92State),
 118     .instance_init = port92_initfn,
 119     .class_init    = port92_class_initfn,
 120 };
 121
 122 static void port92_register_types(void)
 123 {
 124     type_register_static(&port92_info);
 125 }
 126
 127 type_init(port92_register_types)