2 * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
3 * Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM
4 * Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
5 * Copyright (C) 2004 IBM Corporation
7 * Additional Author(s):
8 * Ryan S. Arnold <rsa@us.ibm.com>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
25 #include <linux/console.h>
26 #include <linux/cpumask.h>
27 #include <linux/init.h>
28 #include <linux/kbd_kern.h>
29 #include <linux/kernel.h>
30 #include <linux/kthread.h>
31 #include <linux/list.h>
32 #include <linux/init.h>
33 #include <linux/major.h>
34 #include <linux/atomic.h>
35 #include <linux/sysrq.h>
36 #include <linux/tty.h>
37 #include <linux/tty_flip.h>
38 #include <linux/sched.h>
39 #include <linux/spinlock.h>
40 #include <linux/delay.h>
41 #include <linux/freezer.h>
42 #include <linux/slab.h>
43 #include <linux/serial_core.h>
45 #include <asm/uaccess.h>
47 #include "hvc_console.h"
53 * Wait this long per iteration while trying to push buffered data to the
54 * hypervisor before allowing the tty to complete a close operation.
56 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
59 * These sizes are most efficient for vio, because they are the
60 * native transfer size. We could make them selectable in the
61 * future to better deal with backends that want other buffer sizes.
66 #define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
68 static struct tty_driver *hvc_driver;
69 static struct task_struct *hvc_task;
71 /* Picks up late kicks after list walk but before schedule() */
72 static int hvc_kicked;
74 /* hvc_init is triggered from hvc_alloc, i.e. only when actually used */
75 static atomic_t hvc_needs_init __read_mostly = ATOMIC_INIT(-1);
77 static int hvc_init(void);
79 #ifdef CONFIG_MAGIC_SYSRQ
80 static int sysrq_pressed;
83 /* dynamic list of hvc_struct instances */
84 static LIST_HEAD(hvc_structs);
87 * Protect the list of hvc_struct instances from inserts and removals during
90 static DEFINE_SPINLOCK(hvc_structs_lock);
93 * This value is used to assign a tty->index value to a hvc_struct based
94 * upon order of exposure via hvc_probe(), when we can not match it to
95 * a console candidate registered with hvc_instantiate().
97 static int last_hvc = -1;
100 * Do not call this function with either the hvc_structs_lock or the hvc_struct
101 * lock held. If successful, this function increments the kref reference
102 * count against the target hvc_struct so it should be released when finished.
104 static struct hvc_struct *hvc_get_by_index(int index)
106 struct hvc_struct *hp;
109 spin_lock(&hvc_structs_lock);
111 list_for_each_entry(hp, &hvc_structs, next) {
112 spin_lock_irqsave(&hp->lock, flags);
113 if (hp->index == index) {
114 tty_port_get(&hp->port);
115 spin_unlock_irqrestore(&hp->lock, flags);
116 spin_unlock(&hvc_structs_lock);
119 spin_unlock_irqrestore(&hp->lock, flags);
123 spin_unlock(&hvc_structs_lock);
129 * Initial console vtermnos for console API usage prior to full console
130 * initialization. Any vty adapter outside this range will not have usable
131 * console interfaces but can still be used as a tty device. This has to be
132 * static because kmalloc will not work during early console init.
134 static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
135 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
136 {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
139 * Console APIs, NOT TTY. These APIs are available immediately when
140 * hvc_console_setup() finds adapters.
143 static void hvc_console_print(struct console *co, const char *b,
146 char c[N_OUTBUF] __ALIGNED__;
147 unsigned i = 0, n = 0;
148 int r, donecr = 0, index = co->index;
150 /* Console access attempt outside of acceptable console range. */
151 if (index >= MAX_NR_HVC_CONSOLES)
154 /* This console adapter was removed so it is not usable. */
155 if (vtermnos[index] == -1)
158 while (count > 0 || i > 0) {
159 if (count > 0 && i < sizeof(c)) {
160 if (b[n] == '\n' && !donecr) {
169 r = cons_ops[index]->put_chars(vtermnos[index], c, i);
171 /* throw away characters on error
172 * but spin in case of -EAGAIN */
184 static struct tty_driver *hvc_console_device(struct console *c, int *index)
186 if (vtermnos[c->index] == -1)
193 static int hvc_console_setup(struct console *co, char *options)
195 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
198 if (vtermnos[co->index] == -1)
204 static struct console hvc_console = {
206 .write = hvc_console_print,
207 .device = hvc_console_device,
208 .setup = hvc_console_setup,
209 .flags = CON_PRINTBUFFER,
214 * Early console initialization. Precedes driver initialization.
216 * (1) we are first, and the user specified another driver
217 * -- index will remain -1
218 * (2) we are first and the user specified no driver
219 * -- index will be set to 0, then we will fail setup.
220 * (3) we are first and the user specified our driver
221 * -- index will be set to user specified driver, and we will fail
222 * (4) we are after driver, and this initcall will register us
223 * -- if the user didn't specify a driver then the console will match
225 * Note that for cases 2 and 3, we will match later when the io driver
226 * calls hvc_instantiate() and call register again.
228 static int __init hvc_console_init(void)
230 register_console(&hvc_console);
233 console_initcall(hvc_console_init);
235 /* callback when the kboject ref count reaches zero. */
236 static void hvc_port_destruct(struct tty_port *port)
238 struct hvc_struct *hp = container_of(port, struct hvc_struct, port);
241 spin_lock(&hvc_structs_lock);
243 spin_lock_irqsave(&hp->lock, flags);
244 list_del(&(hp->next));
245 spin_unlock_irqrestore(&hp->lock, flags);
247 spin_unlock(&hvc_structs_lock);
252 static void hvc_check_console(int index)
254 /* Already enabled, bail out */
255 if (hvc_console.flags & CON_ENABLED)
258 /* If this index is what the user requested, then register
259 * now (setup won't fail at this point). It's ok to just
260 * call register again if previously .setup failed.
262 if (index == hvc_console.index)
263 register_console(&hvc_console);
267 * hvc_instantiate() is an early console discovery method which locates
268 * consoles * prior to the vio subsystem discovering them. Hotplugged
269 * vty adapters do NOT get an hvc_instantiate() callback since they
270 * appear after early console init.
272 int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
274 struct hvc_struct *hp;
276 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
279 if (vtermnos[index] != -1)
282 /* make sure no no tty has been registered in this index */
283 hp = hvc_get_by_index(index);
285 tty_port_put(&hp->port);
289 vtermnos[index] = vtermno;
290 cons_ops[index] = ops;
292 /* check if we need to re-register the kernel console */
293 hvc_check_console(index);
297 EXPORT_SYMBOL_GPL(hvc_instantiate);
299 /* Wake the sleeping khvcd */
303 wake_up_process(hvc_task);
305 EXPORT_SYMBOL_GPL(hvc_kick);
307 static void hvc_unthrottle(struct tty_struct *tty)
312 static int hvc_install(struct tty_driver *driver, struct tty_struct *tty)
314 struct hvc_struct *hp;
317 /* Auto increments kref reference if found. */
318 hp = hvc_get_by_index(tty->index);
322 tty->driver_data = hp;
324 rc = tty_port_install(&hp->port, driver, tty);
326 tty_port_put(&hp->port);
331 * The TTY interface won't be used until after the vio layer has exposed the vty
332 * adapter to the kernel.
334 static int hvc_open(struct tty_struct *tty, struct file * filp)
336 struct hvc_struct *hp = tty->driver_data;
340 spin_lock_irqsave(&hp->port.lock, flags);
341 /* Check and then increment for fast path open. */
342 if (hp->port.count++ > 0) {
343 spin_unlock_irqrestore(&hp->port.lock, flags);
346 } /* else count == 0 */
347 spin_unlock_irqrestore(&hp->port.lock, flags);
349 tty_port_tty_set(&hp->port, tty);
351 if (hp->ops->notifier_add)
352 rc = hp->ops->notifier_add(hp, hp->data);
355 * If the notifier fails we return an error. The tty layer
356 * will call hvc_close() after a failed open but we don't want to clean
357 * up there so we'll clean up here and clear out the previously set
358 * tty fields and return the kref reference.
361 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
363 /* We are ready... raise DTR/RTS */
365 if (hp->ops->dtr_rts)
366 hp->ops->dtr_rts(hp, 1);
367 tty_port_set_initialized(&hp->port, true);
370 /* Force wakeup of the polling thread */
376 static void hvc_close(struct tty_struct *tty, struct file * filp)
378 struct hvc_struct *hp = tty->driver_data;
381 if (tty_hung_up_p(filp))
384 spin_lock_irqsave(&hp->port.lock, flags);
386 if (--hp->port.count == 0) {
387 spin_unlock_irqrestore(&hp->port.lock, flags);
388 /* We are done with the tty pointer now. */
389 tty_port_tty_set(&hp->port, NULL);
391 if (!tty_port_initialized(&hp->port))
395 if (hp->ops->dtr_rts)
396 hp->ops->dtr_rts(hp, 0);
398 if (hp->ops->notifier_del)
399 hp->ops->notifier_del(hp, hp->data);
401 /* cancel pending tty resize work */
402 cancel_work_sync(&hp->tty_resize);
405 * Chain calls chars_in_buffer() and returns immediately if
406 * there is no buffered data otherwise sleeps on a wait queue
407 * waking periodically to check chars_in_buffer().
409 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
410 tty_port_set_initialized(&hp->port, false);
412 if (hp->port.count < 0)
413 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
414 hp->vtermno, hp->port.count);
415 spin_unlock_irqrestore(&hp->port.lock, flags);
419 static void hvc_cleanup(struct tty_struct *tty)
421 struct hvc_struct *hp = tty->driver_data;
423 tty_port_put(&hp->port);
426 static void hvc_hangup(struct tty_struct *tty)
428 struct hvc_struct *hp = tty->driver_data;
434 /* cancel pending tty resize work */
435 cancel_work_sync(&hp->tty_resize);
437 spin_lock_irqsave(&hp->port.lock, flags);
440 * The N_TTY line discipline has problems such that in a close vs
441 * open->hangup case this can be called after the final close so prevent
442 * that from happening for now.
444 if (hp->port.count <= 0) {
445 spin_unlock_irqrestore(&hp->port.lock, flags);
450 spin_unlock_irqrestore(&hp->port.lock, flags);
451 tty_port_tty_set(&hp->port, NULL);
455 if (hp->ops->notifier_hangup)
456 hp->ops->notifier_hangup(hp, hp->data);
460 * Push buffered characters whether they were just recently buffered or waiting
461 * on a blocked hypervisor. Call this function with hp->lock held.
463 static int hvc_push(struct hvc_struct *hp)
467 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
469 if (n == 0 || n == -EAGAIN) {
473 /* throw away output on error; this happens when
474 there is no session connected to the vterm. */
478 if (hp->n_outbuf > 0)
479 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
486 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
488 struct hvc_struct *hp = tty->driver_data;
490 int rsize, written = 0;
492 /* This write was probably executed during a tty close. */
496 /* FIXME what's this (unprotected) check for? */
497 if (hp->port.count <= 0)
500 spin_lock_irqsave(&hp->lock, flags);
502 /* Push pending writes */
503 if (hp->n_outbuf > 0)
506 while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
509 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
512 hp->n_outbuf += rsize;
516 spin_unlock_irqrestore(&hp->lock, flags);
519 * Racy, but harmless, kick thread if there is still pending data.
528 * hvc_set_winsz() - Resize the hvc tty terminal window.
529 * @work: work structure.
531 * The routine shall not be called within an atomic context because it
536 static void hvc_set_winsz(struct work_struct *work)
538 struct hvc_struct *hp;
539 unsigned long hvc_flags;
540 struct tty_struct *tty;
543 hp = container_of(work, struct hvc_struct, tty_resize);
545 tty = tty_port_tty_get(&hp->port);
549 spin_lock_irqsave(&hp->lock, hvc_flags);
551 spin_unlock_irqrestore(&hp->lock, hvc_flags);
553 tty_do_resize(tty, &ws);
558 * This is actually a contract between the driver and the tty layer outlining
559 * how much write room the driver can guarantee will be sent OR BUFFERED. This
560 * driver MUST honor the return value.
562 static int hvc_write_room(struct tty_struct *tty)
564 struct hvc_struct *hp = tty->driver_data;
569 return hp->outbuf_size - hp->n_outbuf;
572 static int hvc_chars_in_buffer(struct tty_struct *tty)
574 struct hvc_struct *hp = tty->driver_data;
582 * timeout will vary between the MIN and MAX values defined here. By default
583 * and during console activity we will use a default MIN_TIMEOUT of 10. When
584 * the console is idle, we increase the timeout value on each pass through
585 * msleep until we reach the max. This may be noticeable as a brief (average
586 * one second) delay on the console before the console responds to input when
587 * there has been no input for some time.
589 #define MIN_TIMEOUT (10)
590 #define MAX_TIMEOUT (2000)
591 static u32 timeout = MIN_TIMEOUT;
593 #define HVC_POLL_READ 0x00000001
594 #define HVC_POLL_WRITE 0x00000002
596 int hvc_poll(struct hvc_struct *hp)
598 struct tty_struct *tty;
599 int i, n, poll_mask = 0;
600 char buf[N_INBUF] __ALIGNED__;
603 int written_total = 0;
605 spin_lock_irqsave(&hp->lock, flags);
607 /* Push pending writes */
608 if (hp->n_outbuf > 0)
609 written_total = hvc_push(hp);
611 /* Reschedule us if still some write pending */
612 if (hp->n_outbuf > 0) {
613 poll_mask |= HVC_POLL_WRITE;
614 /* If hvc_push() was not able to write, sleep a few msecs */
615 timeout = (written_total) ? 0 : MIN_TIMEOUT;
618 /* No tty attached, just skip */
619 tty = tty_port_tty_get(&hp->port);
623 /* Now check if we can get data (are we throttled ?) */
624 if (tty_throttled(tty))
627 /* If we aren't notifier driven and aren't throttled, we always
628 * request a reschedule
630 if (!hp->irq_requested)
631 poll_mask |= HVC_POLL_READ;
633 /* Read data if any */
635 int count = tty_buffer_request_room(&hp->port, N_INBUF);
637 /* If flip is full, just reschedule a later read */
639 poll_mask |= HVC_POLL_READ;
643 n = hp->ops->get_chars(hp->vtermno, buf, count);
645 /* Hangup the tty when disconnected from host */
647 spin_unlock_irqrestore(&hp->lock, flags);
649 spin_lock_irqsave(&hp->lock, flags);
650 } else if ( n == -EAGAIN ) {
652 * Some back-ends can only ensure a certain min
653 * num of bytes read, which may be > 'count'.
654 * Let the tty clear the flip buff to make room.
656 poll_mask |= HVC_POLL_READ;
660 for (i = 0; i < n; ++i) {
661 #ifdef CONFIG_MAGIC_SYSRQ
662 if (hp->index == hvc_console.index) {
663 /* Handle the SysRq Hack */
664 /* XXX should support a sequence */
665 if (buf[i] == '\x0f') { /* ^O */
666 /* if ^O is pressed again, reset
667 * sysrq_pressed and flip ^O char */
668 sysrq_pressed = !sysrq_pressed;
671 } else if (sysrq_pressed) {
672 handle_sysrq(buf[i]);
677 #endif /* CONFIG_MAGIC_SYSRQ */
678 tty_insert_flip_char(&hp->port, buf[i], 0);
684 /* Wakeup write queue if necessary */
690 spin_unlock_irqrestore(&hp->lock, flags);
693 /* Activity is occurring, so reset the polling backoff value to
694 a minimum for performance. */
695 timeout = MIN_TIMEOUT;
697 tty_flip_buffer_push(&hp->port);
703 EXPORT_SYMBOL_GPL(hvc_poll);
706 * __hvc_resize() - Update terminal window size information.
707 * @hp: HVC console pointer
708 * @ws: Terminal window size structure
710 * Stores the specified window size information in the hvc structure of @hp.
711 * The function schedule the tty resize update.
713 * Locking: Locking free; the function MUST be called holding hp->lock
715 void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
718 schedule_work(&hp->tty_resize);
720 EXPORT_SYMBOL_GPL(__hvc_resize);
723 * This kthread is either polling or interrupt driven. This is determined by
724 * calling hvc_poll() who determines whether a console adapter support
727 static int khvcd(void *unused)
730 struct hvc_struct *hp;
738 if (!cpus_are_in_xmon()) {
739 spin_lock(&hvc_structs_lock);
740 list_for_each_entry(hp, &hvc_structs, next) {
741 poll_mask |= hvc_poll(hp);
743 spin_unlock(&hvc_structs_lock);
745 poll_mask |= HVC_POLL_READ;
748 set_current_state(TASK_INTERRUPTIBLE);
753 unsigned long j_timeout;
755 if (timeout < MAX_TIMEOUT)
756 timeout += (timeout >> 6) + 1;
759 * We don't use msleep_interruptible otherwise
760 * "kick" will fail to wake us up
762 j_timeout = msecs_to_jiffies(timeout) + 1;
763 schedule_timeout_interruptible(j_timeout);
766 __set_current_state(TASK_RUNNING);
767 } while (!kthread_should_stop());
772 static int hvc_tiocmget(struct tty_struct *tty)
774 struct hvc_struct *hp = tty->driver_data;
776 if (!hp || !hp->ops->tiocmget)
778 return hp->ops->tiocmget(hp);
781 static int hvc_tiocmset(struct tty_struct *tty,
782 unsigned int set, unsigned int clear)
784 struct hvc_struct *hp = tty->driver_data;
786 if (!hp || !hp->ops->tiocmset)
788 return hp->ops->tiocmset(hp, set, clear);
791 #ifdef CONFIG_CONSOLE_POLL
792 static int hvc_poll_init(struct tty_driver *driver, int line, char *options)
797 static int hvc_poll_get_char(struct tty_driver *driver, int line)
799 struct tty_struct *tty = driver->ttys[0];
800 struct hvc_struct *hp = tty->driver_data;
804 n = hp->ops->get_chars(hp->vtermno, &ch, 1);
812 static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
814 struct tty_struct *tty = driver->ttys[0];
815 struct hvc_struct *hp = tty->driver_data;
819 n = hp->ops->put_chars(hp->vtermno, &ch, 1);
824 static const struct tty_operations hvc_ops = {
825 .install = hvc_install,
828 .cleanup = hvc_cleanup,
830 .hangup = hvc_hangup,
831 .unthrottle = hvc_unthrottle,
832 .write_room = hvc_write_room,
833 .chars_in_buffer = hvc_chars_in_buffer,
834 .tiocmget = hvc_tiocmget,
835 .tiocmset = hvc_tiocmset,
836 #ifdef CONFIG_CONSOLE_POLL
837 .poll_init = hvc_poll_init,
838 .poll_get_char = hvc_poll_get_char,
839 .poll_put_char = hvc_poll_put_char,
843 static const struct tty_port_operations hvc_port_ops = {
844 .destruct = hvc_port_destruct,
847 struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
848 const struct hv_ops *ops,
851 struct hvc_struct *hp;
854 /* We wait until a driver actually comes along */
855 if (atomic_inc_not_zero(&hvc_needs_init)) {
856 int err = hvc_init();
861 hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
864 return ERR_PTR(-ENOMEM);
866 hp->vtermno = vtermno;
869 hp->outbuf_size = outbuf_size;
870 hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
872 tty_port_init(&hp->port);
873 hp->port.ops = &hvc_port_ops;
875 INIT_WORK(&hp->tty_resize, hvc_set_winsz);
876 spin_lock_init(&hp->lock);
877 spin_lock(&hvc_structs_lock);
881 * see if this vterm id matches one registered for console.
883 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
884 if (vtermnos[i] == hp->vtermno &&
885 cons_ops[i] == hp->ops)
888 if (i >= MAX_NR_HVC_CONSOLES) {
890 /* find 'empty' slot for console */
891 for (i = 0; i < MAX_NR_HVC_CONSOLES && vtermnos[i] != -1; i++) {
894 /* no matching slot, just use a counter */
895 if (i == MAX_NR_HVC_CONSOLES)
896 i = ++last_hvc + MAX_NR_HVC_CONSOLES;
900 if (i < MAX_NR_HVC_CONSOLES) {
902 vtermnos[i] = vtermno;
905 list_add_tail(&(hp->next), &hvc_structs);
906 spin_unlock(&hvc_structs_lock);
908 /* check if we need to re-register the kernel console */
909 hvc_check_console(i);
913 EXPORT_SYMBOL_GPL(hvc_alloc);
915 int hvc_remove(struct hvc_struct *hp)
918 struct tty_struct *tty;
920 tty = tty_port_tty_get(&hp->port);
922 spin_lock_irqsave(&hp->lock, flags);
923 if (hp->index < MAX_NR_HVC_CONSOLES) {
925 vtermnos[hp->index] = -1;
926 cons_ops[hp->index] = NULL;
930 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
932 spin_unlock_irqrestore(&hp->lock, flags);
935 * We 'put' the instance that was grabbed when the kref instance
936 * was initialized using kref_init(). Let the last holder of this
937 * kref cause it to be removed, which will probably be the tty_vhangup
940 tty_port_put(&hp->port);
943 * This function call will auto chain call hvc_hangup.
951 EXPORT_SYMBOL_GPL(hvc_remove);
953 /* Driver initialization: called as soon as someone uses hvc_alloc(). */
954 static int hvc_init(void)
956 struct tty_driver *drv;
959 /* We need more than hvc_count adapters due to hotplug additions. */
960 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
966 drv->driver_name = "hvc";
968 drv->major = HVC_MAJOR;
969 drv->minor_start = HVC_MINOR;
970 drv->type = TTY_DRIVER_TYPE_SYSTEM;
971 drv->init_termios = tty_std_termios;
972 drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
973 tty_set_operations(drv, &hvc_ops);
975 /* Always start the kthread because there can be hotplug vty adapters
977 hvc_task = kthread_run(khvcd, NULL, "khvcd");
978 if (IS_ERR(hvc_task)) {
979 printk(KERN_ERR "Couldn't create kthread for console.\n");
980 err = PTR_ERR(hvc_task);
984 err = tty_register_driver(drv);
986 printk(KERN_ERR "Couldn't register hvc console driver\n");
991 * Make sure tty is fully registered before allowing it to be
992 * found by hvc_console_device.
999 kthread_stop(hvc_task);
1002 put_tty_driver(drv);