port92: handle A20 IRQ as GPIO

The port92 device has outgouing IRQ line A20. Currently the IRQ is referenced
by a pointer which normally is set during machine initialization. The
pointer is never changed at runtime. Hence, common GPIO model can be applied
to A20 IRQ line. Note that checking for IRQ to be connected as in
previous version of code is not required qemu_set_irq will do it.
Signed-off-by: NEfimov Vasily <real@ispras.ru>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/i386/pc.c

@@ -505,7 +505,7 @@ typedef struct Port92State {
 
     MemoryRegion io;
     uint8_t outport;
-    qemu_irq *a20_out;
+    qemu_irq a20_out;
 } Port92State;
 
 static void port92_write(void *opaque, hwaddr addr, uint64_t val,
@@ -516,7 +516,7 @@ static void port92_write(void *opaque, hwaddr addr, uint64_t val,
 
     DPRINTF("port92: write 0x%02" PRIx64 "\n", val);
     s->outport = val;
-    qemu_set_irq(*s->a20_out, (val >> 1) & 1);
+    qemu_set_irq(s->a20_out, (val >> 1) & 1);
     if ((val & 1) && !(oldval & 1)) {
         qemu_system_reset_request();
     }
@@ -535,9 +535,7 @@ static uint64_t port92_read(void *opaque, hwaddr addr,
 
 static void port92_init(ISADevice *dev, qemu_irq *a20_out)
 {
-    Port92State *s = PORT92(dev);
-
-    s->a20_out = a20_out;
+    qdev_connect_gpio_out_named(DEVICE(dev), PORT92_A20_LINE, 0, *a20_out);
 }
 
 static const VMStateDescription vmstate_port92_isa = {
@@ -574,6 +572,8 @@ static void port92_initfn(Object *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)

include/hw/i386/pc.h

@@ -277,6 +277,8 @@ int cmos_get_fd_drive_type(FloppyDriveType fd0);
 
 #define FW_CFG_IO_BASE     0x510
 
+#define PORT92_A20_LINE "a20"
+
 /* acpi_piix.c */
 
 I2CBus *piix4_pm_init(PCIBus *bus, int devfn, uint32_t smb_io_base,