+EXPORT_SYMBOL(con_is_bound);
+
+/**
+ * register_con_driver - register console driver to console layer
+ * @csw: console driver
+ * @first: the first console to take over, minimum value is 0
+ * @last: the last console to take over, maximum value is MAX_NR_CONSOLES -1
+ *
+ * DESCRIPTION: This function registers a console driver which can later
+ * bind to a range of consoles specified by @first and @last. It will
+ * also initialize the console driver by calling con_startup().
+ */
+int register_con_driver(const struct consw *csw, int first, int last)
+{
+ struct module *owner = csw->owner;
+ struct con_driver *con_driver;
+ const char *desc;
+ int i, retval = 0;
+
+ if (!try_module_get(owner))
+ return -ENODEV;
+
+ acquire_console_sem();
+
+ for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
+ con_driver = ®istered_con_driver[i];
+
+ /* already registered */
+ if (con_driver->con == csw)
+ retval = -EINVAL;
+ }
+
+ if (retval)
+ goto err;
+
+ desc = csw->con_startup();
+
+ if (!desc)
+ goto err;
+
+ retval = -EINVAL;
+
+ for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
+ con_driver = ®istered_con_driver[i];
+
+ if (con_driver->con == NULL) {
+ con_driver->con = csw;
+ con_driver->desc = desc;
+ con_driver->node = i;
+ con_driver->flag = CON_DRIVER_FLAG_MODULE |
+ CON_DRIVER_FLAG_INIT;
+ con_driver->first = first;
+ con_driver->last = last;
+ retval = 0;
+ break;
+ }
+ }
+
+ if (retval)
+ goto err;
+
+ con_driver->dev = device_create(vtconsole_class, NULL,
+ MKDEV(0, con_driver->node),
+ "vtcon%i", con_driver->node);
+
+ if (IS_ERR(con_driver->dev)) {
+ printk(KERN_WARNING "Unable to create device for %s; "
+ "errno = %ld\n", con_driver->desc,
+ PTR_ERR(con_driver->dev));
+ con_driver->dev = NULL;
+ } else {
+ vtconsole_init_device(con_driver);
+ }
+
+err:
+ release_console_sem();
+ module_put(owner);
+ return retval;
+}
+EXPORT_SYMBOL(register_con_driver);
+
+/**
+ * unregister_con_driver - unregister console driver from console layer
+ * @csw: console driver
+ *
+ * DESCRIPTION: All drivers that registers to the console layer must
+ * call this function upon exit, or if the console driver is in a state
+ * where it won't be able to handle console services, such as the
+ * framebuffer console without loaded framebuffer drivers.
+ *
+ * The driver must unbind first prior to unregistration.
+ */
+int unregister_con_driver(const struct consw *csw)
+{
+ int i, retval = -ENODEV;
+
+ acquire_console_sem();
+
+ /* cannot unregister a bound driver */
+ if (con_is_bound(csw))
+ goto err;
+
+ for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
+ struct con_driver *con_driver = ®istered_con_driver[i];
+
+ if (con_driver->con == csw &&
+ con_driver->flag & CON_DRIVER_FLAG_MODULE) {
+ vtconsole_deinit_device(con_driver);
+ device_destroy(vtconsole_class,
+ MKDEV(0, con_driver->node));
+ con_driver->con = NULL;
+ con_driver->desc = NULL;
+ con_driver->dev = NULL;
+ con_driver->node = 0;
+ con_driver->flag = 0;
+ con_driver->first = 0;
+ con_driver->last = 0;
+ retval = 0;
+ break;
+ }
+ }
+err:
+ release_console_sem();
+ return retval;
+}
+EXPORT_SYMBOL(unregister_con_driver);
+
+/*
+ * If we support more console drivers, this function is used
+ * when a driver wants to take over some existing consoles
+ * and become default driver for newly opened ones.
+ *
+ * take_over_console is basically a register followed by unbind
+ */
+int take_over_console(const struct consw *csw, int first, int last, int deflt)
+{
+ int err;
+
+ err = register_con_driver(csw, first, last);
+
+ if (!err)
+ bind_con_driver(csw, first, last, deflt);
+
+ return err;
+}
+
+/*
+ * give_up_console is a wrapper to unregister_con_driver. It will only
+ * work if driver is fully unbound.
+ */
+void give_up_console(const struct consw *csw)
+{
+ unregister_con_driver(csw);
+}
+
+static int __init vtconsole_class_init(void)
+{
+ int i;
+
+ vtconsole_class = class_create(THIS_MODULE, "vtconsole");
+ if (IS_ERR(vtconsole_class)) {
+ printk(KERN_WARNING "Unable to create vt console class; "
+ "errno = %ld\n", PTR_ERR(vtconsole_class));
+ vtconsole_class = NULL;
+ }
+
+ /* Add system drivers to sysfs */
+ for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
+ struct con_driver *con = ®istered_con_driver[i];
+
+ if (con->con && !con->dev) {
+ con->dev = device_create(vtconsole_class, NULL,
+ MKDEV(0, con->node),
+ "vtcon%i", con->node);
+
+ if (IS_ERR(con->dev)) {
+ printk(KERN_WARNING "Unable to create "
+ "device for %s; errno = %ld\n",
+ con->desc, PTR_ERR(con->dev));
+ con->dev = NULL;
+ } else {
+ vtconsole_init_device(con);
+ }
+ }
+ }
+
+ return 0;
+}
+postcore_initcall(vtconsole_class_init);