s390x/3270: Add emulated terminal3270 device

This is a basic implementation of the emulated ccw-attached 3270
called x-terminal3270, which provides visibility of the device in
the qemu monitor and guest. The x prefix indicates that this is
just an experimental implementation for the current stage. This
device will not be compiled until the basic functions are available.

Signed-off-by: Yang Chen <bjcyang@linux.vnet.ibm.com>
Signed-off-by: Jing Liu <liujbjl@linux.vnet.ibm.com>
Reviewed-by: QingFeng Hao <haoqf@linux.vnet.ibm.com>
Reviewed-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

hw/char/terminal3270.c

@@ -0,0 +1,54 @@
+/*
+ * Terminal 3270 implementation
+ *
+ * Copyright 2017 IBM Corp.
+ *
+ * Authors: Yang Chen <bjcyang@linux.vnet.ibm.com>
+ *          Jing Liu <liujbjl@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or (at
+ * your option) any later version. See the COPYING file in the top-level
+ * directory.
+ */
+
+#include "qemu/osdep.h"
+#include "hw/s390x/3270-ccw.h"
+
+typedef struct Terminal3270 {
+    EmulatedCcw3270Device cdev;
+} Terminal3270;
+
+#define TYPE_TERMINAL_3270 "x-terminal3270"
+
+static void terminal_init(EmulatedCcw3270Device *dev, Error **errp)
+{
+    static bool terminal_available;
+
+    if (terminal_available) {
+        error_setg(errp, "Multiple 3270 terminals are not supported.");
+        return;
+    }
+    terminal_available = true;
+}
+
+static void terminal_class_init(ObjectClass *klass, void *data)
+{
+    EmulatedCcw3270Class *ck = EMULATED_CCW_3270_CLASS(klass);
+
+    ck->init = terminal_init;
+}
+
+static const TypeInfo ccw_terminal_info = {
+    .name = TYPE_TERMINAL_3270,
+    .parent = TYPE_EMULATED_CCW_3270,
+    .instance_size = sizeof(Terminal3270),
+    .class_init = terminal_class_init,
+    .class_size = sizeof(EmulatedCcw3270Class),
+};
+
+static void register_types(void)
+{
+    type_register_static(&ccw_terminal_info);
+}
+
+type_init(register_types)