knfsd: nfsd4: fix handling of acl errrors
[pv_ops_mirror.git] / drivers / char / hvc_console.c
blob83c1151ec7a21559257f3663a59d0f59e4d92abc
1 /*
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/kobject.h>
31 #include <linux/kthread.h>
32 #include <linux/list.h>
33 #include <linux/module.h>
34 #include <linux/major.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>
43 #include <asm/uaccess.h>
45 #include "hvc_console.h"
47 #define HVC_MAJOR 229
48 #define HVC_MINOR 0
51 * Wait this long per iteration while trying to push buffered data to the
52 * hypervisor before allowing the tty to complete a close operation.
54 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
57 * These sizes are most efficient for vio, because they are the
58 * native transfer size. We could make them selectable in the
59 * future to better deal with backends that want other buffer sizes.
61 #define N_OUTBUF 16
62 #define N_INBUF 16
64 #define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
66 static struct tty_driver *hvc_driver;
67 static struct task_struct *hvc_task;
69 /* Picks up late kicks after list walk but before schedule() */
70 static int hvc_kicked;
72 #ifdef CONFIG_MAGIC_SYSRQ
73 static int sysrq_pressed;
74 #endif
76 struct hvc_struct {
77 spinlock_t lock;
78 int index;
79 struct tty_struct *tty;
80 unsigned int count;
81 int do_wakeup;
82 char *outbuf;
83 int outbuf_size;
84 int n_outbuf;
85 uint32_t vtermno;
86 struct hv_ops *ops;
87 int irq_requested;
88 int irq;
89 struct list_head next;
90 struct kobject kobj; /* ref count & hvc_struct lifetime */
93 /* dynamic list of hvc_struct instances */
94 static struct list_head hvc_structs = LIST_HEAD_INIT(hvc_structs);
97 * Protect the list of hvc_struct instances from inserts and removals during
98 * list traversal.
100 static DEFINE_SPINLOCK(hvc_structs_lock);
103 * This value is used to assign a tty->index value to a hvc_struct based
104 * upon order of exposure via hvc_probe(), when we can not match it to
105 * a console candidate registered with hvc_instantiate().
107 static int last_hvc = -1;
110 * Do not call this function with either the hvc_structs_lock or the hvc_struct
111 * lock held. If successful, this function increments the kobject reference
112 * count against the target hvc_struct so it should be released when finished.
114 static struct hvc_struct *hvc_get_by_index(int index)
116 struct hvc_struct *hp;
117 unsigned long flags;
119 spin_lock(&hvc_structs_lock);
121 list_for_each_entry(hp, &hvc_structs, next) {
122 spin_lock_irqsave(&hp->lock, flags);
123 if (hp->index == index) {
124 kobject_get(&hp->kobj);
125 spin_unlock_irqrestore(&hp->lock, flags);
126 spin_unlock(&hvc_structs_lock);
127 return hp;
129 spin_unlock_irqrestore(&hp->lock, flags);
131 hp = NULL;
133 spin_unlock(&hvc_structs_lock);
134 return hp;
139 * Initial console vtermnos for console API usage prior to full console
140 * initialization. Any vty adapter outside this range will not have usable
141 * console interfaces but can still be used as a tty device. This has to be
142 * static because kmalloc will not work during early console init.
144 static struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
145 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
146 {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
149 * Console APIs, NOT TTY. These APIs are available immediately when
150 * hvc_console_setup() finds adapters.
153 static void hvc_console_print(struct console *co, const char *b,
154 unsigned count)
156 char c[N_OUTBUF] __ALIGNED__;
157 unsigned i = 0, n = 0;
158 int r, donecr = 0, index = co->index;
160 /* Console access attempt outside of acceptable console range. */
161 if (index >= MAX_NR_HVC_CONSOLES)
162 return;
164 /* This console adapter was removed so it is not usable. */
165 if (vtermnos[index] < 0)
166 return;
168 while (count > 0 || i > 0) {
169 if (count > 0 && i < sizeof(c)) {
170 if (b[n] == '\n' && !donecr) {
171 c[i++] = '\r';
172 donecr = 1;
173 } else {
174 c[i++] = b[n++];
175 donecr = 0;
176 --count;
178 } else {
179 r = cons_ops[index]->put_chars(vtermnos[index], c, i);
180 if (r < 0) {
181 /* throw away chars on error */
182 i = 0;
183 } else if (r > 0) {
184 i -= r;
185 if (i > 0)
186 memmove(c, c+r, i);
192 static struct tty_driver *hvc_console_device(struct console *c, int *index)
194 if (vtermnos[c->index] == -1)
195 return NULL;
197 *index = c->index;
198 return hvc_driver;
201 static int __init hvc_console_setup(struct console *co, char *options)
203 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
204 return -ENODEV;
206 if (vtermnos[co->index] == -1)
207 return -ENODEV;
209 return 0;
212 static struct console hvc_con_driver = {
213 .name = "hvc",
214 .write = hvc_console_print,
215 .device = hvc_console_device,
216 .setup = hvc_console_setup,
217 .flags = CON_PRINTBUFFER,
218 .index = -1,
222 * Early console initialization. Precedes driver initialization.
224 * (1) we are first, and the user specified another driver
225 * -- index will remain -1
226 * (2) we are first and the user specified no driver
227 * -- index will be set to 0, then we will fail setup.
228 * (3) we are first and the user specified our driver
229 * -- index will be set to user specified driver, and we will fail
230 * (4) we are after driver, and this initcall will register us
231 * -- if the user didn't specify a driver then the console will match
233 * Note that for cases 2 and 3, we will match later when the io driver
234 * calls hvc_instantiate() and call register again.
236 static int __init hvc_console_init(void)
238 register_console(&hvc_con_driver);
239 return 0;
241 console_initcall(hvc_console_init);
244 * hvc_instantiate() is an early console discovery method which locates
245 * consoles * prior to the vio subsystem discovering them. Hotplugged
246 * vty adapters do NOT get an hvc_instantiate() callback since they
247 * appear after early console init.
249 int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops)
251 struct hvc_struct *hp;
253 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
254 return -1;
256 if (vtermnos[index] != -1)
257 return -1;
259 /* make sure no no tty has been registered in this index */
260 hp = hvc_get_by_index(index);
261 if (hp) {
262 kobject_put(&hp->kobj);
263 return -1;
266 vtermnos[index] = vtermno;
267 cons_ops[index] = ops;
269 /* reserve all indices up to and including this index */
270 if (last_hvc < index)
271 last_hvc = index;
273 /* if this index is what the user requested, then register
274 * now (setup won't fail at this point). It's ok to just
275 * call register again if previously .setup failed.
277 if (index == hvc_con_driver.index)
278 register_console(&hvc_con_driver);
280 return 0;
283 /* Wake the sleeping khvcd */
284 static void hvc_kick(void)
286 hvc_kicked = 1;
287 wake_up_process(hvc_task);
290 static int hvc_poll(struct hvc_struct *hp);
293 * NOTE: This API isn't used if the console adapter doesn't support interrupts.
294 * In this case the console is poll driven.
296 static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance)
298 /* if hvc_poll request a repoll, then kick the hvcd thread */
299 if (hvc_poll(dev_instance))
300 hvc_kick();
301 return IRQ_HANDLED;
304 static void hvc_unthrottle(struct tty_struct *tty)
306 hvc_kick();
310 * The TTY interface won't be used until after the vio layer has exposed the vty
311 * adapter to the kernel.
313 static int hvc_open(struct tty_struct *tty, struct file * filp)
315 struct hvc_struct *hp;
316 unsigned long flags;
317 int irq = 0;
318 int rc = 0;
319 struct kobject *kobjp;
321 /* Auto increments kobject reference if found. */
322 if (!(hp = hvc_get_by_index(tty->index)))
323 return -ENODEV;
325 spin_lock_irqsave(&hp->lock, flags);
326 /* Check and then increment for fast path open. */
327 if (hp->count++ > 0) {
328 spin_unlock_irqrestore(&hp->lock, flags);
329 hvc_kick();
330 return 0;
331 } /* else count == 0 */
333 tty->driver_data = hp;
334 tty->low_latency = 1; /* Makes flushes to ldisc synchronous. */
336 hp->tty = tty;
337 /* Save for request_irq outside of spin_lock. */
338 irq = hp->irq;
339 if (irq)
340 hp->irq_requested = 1;
342 kobjp = &hp->kobj;
344 spin_unlock_irqrestore(&hp->lock, flags);
345 /* check error, fallback to non-irq */
346 if (irq)
347 rc = request_irq(irq, hvc_handle_interrupt, IRQF_DISABLED, "hvc_console", hp);
350 * If the request_irq() fails and we return an error. The tty layer
351 * will call hvc_close() after a failed open but we don't want to clean
352 * up there so we'll clean up here and clear out the previously set
353 * tty fields and return the kobject reference.
355 if (rc) {
356 spin_lock_irqsave(&hp->lock, flags);
357 hp->tty = NULL;
358 hp->irq_requested = 0;
359 spin_unlock_irqrestore(&hp->lock, flags);
360 tty->driver_data = NULL;
361 kobject_put(kobjp);
362 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
364 /* Force wakeup of the polling thread */
365 hvc_kick();
367 return rc;
370 static void hvc_close(struct tty_struct *tty, struct file * filp)
372 struct hvc_struct *hp;
373 struct kobject *kobjp;
374 int irq = 0;
375 unsigned long flags;
377 if (tty_hung_up_p(filp))
378 return;
381 * No driver_data means that this close was issued after a failed
382 * hvc_open by the tty layer's release_dev() function and we can just
383 * exit cleanly because the kobject reference wasn't made.
385 if (!tty->driver_data)
386 return;
388 hp = tty->driver_data;
389 spin_lock_irqsave(&hp->lock, flags);
391 kobjp = &hp->kobj;
392 if (--hp->count == 0) {
393 if (hp->irq_requested)
394 irq = hp->irq;
395 hp->irq_requested = 0;
397 /* We are done with the tty pointer now. */
398 hp->tty = NULL;
399 spin_unlock_irqrestore(&hp->lock, flags);
402 * Chain calls chars_in_buffer() and returns immediately if
403 * there is no buffered data otherwise sleeps on a wait queue
404 * waking periodically to check chars_in_buffer().
406 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
408 if (irq)
409 free_irq(irq, hp);
411 } else {
412 if (hp->count < 0)
413 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
414 hp->vtermno, hp->count);
415 spin_unlock_irqrestore(&hp->lock, flags);
418 kobject_put(kobjp);
421 static void hvc_hangup(struct tty_struct *tty)
423 struct hvc_struct *hp = tty->driver_data;
424 unsigned long flags;
425 int irq = 0;
426 int temp_open_count;
427 struct kobject *kobjp;
429 if (!hp)
430 return;
432 spin_lock_irqsave(&hp->lock, flags);
435 * The N_TTY line discipline has problems such that in a close vs
436 * open->hangup case this can be called after the final close so prevent
437 * that from happening for now.
439 if (hp->count <= 0) {
440 spin_unlock_irqrestore(&hp->lock, flags);
441 return;
444 kobjp = &hp->kobj;
445 temp_open_count = hp->count;
446 hp->count = 0;
447 hp->n_outbuf = 0;
448 hp->tty = NULL;
449 if (hp->irq_requested)
450 /* Saved for use outside of spin_lock. */
451 irq = hp->irq;
452 hp->irq_requested = 0;
453 spin_unlock_irqrestore(&hp->lock, flags);
454 if (irq)
455 free_irq(irq, hp);
456 while(temp_open_count) {
457 --temp_open_count;
458 kobject_put(kobjp);
463 * Push buffered characters whether they were just recently buffered or waiting
464 * on a blocked hypervisor. Call this function with hp->lock held.
466 static void hvc_push(struct hvc_struct *hp)
468 int n;
470 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
471 if (n <= 0) {
472 if (n == 0) {
473 hp->do_wakeup = 1;
474 return;
476 /* throw away output on error; this happens when
477 there is no session connected to the vterm. */
478 hp->n_outbuf = 0;
479 } else
480 hp->n_outbuf -= n;
481 if (hp->n_outbuf > 0)
482 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
483 else
484 hp->do_wakeup = 1;
487 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
489 struct hvc_struct *hp = tty->driver_data;
490 unsigned long flags;
491 int rsize, written = 0;
493 /* This write was probably executed during a tty close. */
494 if (!hp)
495 return -EPIPE;
497 if (hp->count <= 0)
498 return -EIO;
500 spin_lock_irqsave(&hp->lock, flags);
502 /* Push pending writes */
503 if (hp->n_outbuf > 0)
504 hvc_push(hp);
506 while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
507 if (rsize > count)
508 rsize = count;
509 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
510 count -= rsize;
511 buf += rsize;
512 hp->n_outbuf += rsize;
513 written += rsize;
514 hvc_push(hp);
516 spin_unlock_irqrestore(&hp->lock, flags);
519 * Racy, but harmless, kick thread if there is still pending data.
521 if (hp->n_outbuf)
522 hvc_kick();
524 return written;
528 * This is actually a contract between the driver and the tty layer outlining
529 * how much write room the driver can guarantee will be sent OR BUFFERED. This
530 * driver MUST honor the return value.
532 static int hvc_write_room(struct tty_struct *tty)
534 struct hvc_struct *hp = tty->driver_data;
536 if (!hp)
537 return -1;
539 return hp->outbuf_size - hp->n_outbuf;
542 static int hvc_chars_in_buffer(struct tty_struct *tty)
544 struct hvc_struct *hp = tty->driver_data;
546 if (!hp)
547 return -1;
548 return hp->n_outbuf;
552 * timeout will vary between the MIN and MAX values defined here. By default
553 * and during console activity we will use a default MIN_TIMEOUT of 10. When
554 * the console is idle, we increase the timeout value on each pass through
555 * msleep until we reach the max. This may be noticeable as a brief (average
556 * one second) delay on the console before the console responds to input when
557 * there has been no input for some time.
559 #define MIN_TIMEOUT (10)
560 #define MAX_TIMEOUT (2000)
561 static u32 timeout = MIN_TIMEOUT;
563 #define HVC_POLL_READ 0x00000001
564 #define HVC_POLL_WRITE 0x00000002
566 static int hvc_poll(struct hvc_struct *hp)
568 struct tty_struct *tty;
569 int i, n, poll_mask = 0;
570 char buf[N_INBUF] __ALIGNED__;
571 unsigned long flags;
572 int read_total = 0;
574 spin_lock_irqsave(&hp->lock, flags);
576 /* Push pending writes */
577 if (hp->n_outbuf > 0)
578 hvc_push(hp);
580 /* Reschedule us if still some write pending */
581 if (hp->n_outbuf > 0)
582 poll_mask |= HVC_POLL_WRITE;
584 /* No tty attached, just skip */
585 tty = hp->tty;
586 if (tty == NULL)
587 goto bail;
589 /* Now check if we can get data (are we throttled ?) */
590 if (test_bit(TTY_THROTTLED, &tty->flags))
591 goto throttled;
593 /* If we aren't interrupt driven and aren't throttled, we always
594 * request a reschedule
596 if (hp->irq == 0)
597 poll_mask |= HVC_POLL_READ;
599 /* Read data if any */
600 for (;;) {
601 int count = tty_buffer_request_room(tty, N_INBUF);
603 /* If flip is full, just reschedule a later read */
604 if (count == 0) {
605 poll_mask |= HVC_POLL_READ;
606 break;
609 n = hp->ops->get_chars(hp->vtermno, buf, count);
610 if (n <= 0) {
611 /* Hangup the tty when disconnected from host */
612 if (n == -EPIPE) {
613 spin_unlock_irqrestore(&hp->lock, flags);
614 tty_hangup(tty);
615 spin_lock_irqsave(&hp->lock, flags);
616 } else if ( n == -EAGAIN ) {
618 * Some back-ends can only ensure a certain min
619 * num of bytes read, which may be > 'count'.
620 * Let the tty clear the flip buff to make room.
622 poll_mask |= HVC_POLL_READ;
624 break;
626 for (i = 0; i < n; ++i) {
627 #ifdef CONFIG_MAGIC_SYSRQ
628 if (hp->index == hvc_con_driver.index) {
629 /* Handle the SysRq Hack */
630 /* XXX should support a sequence */
631 if (buf[i] == '\x0f') { /* ^O */
632 sysrq_pressed = 1;
633 continue;
634 } else if (sysrq_pressed) {
635 handle_sysrq(buf[i], tty);
636 sysrq_pressed = 0;
637 continue;
640 #endif /* CONFIG_MAGIC_SYSRQ */
641 tty_insert_flip_char(tty, buf[i], 0);
644 read_total += n;
646 throttled:
647 /* Wakeup write queue if necessary */
648 if (hp->do_wakeup) {
649 hp->do_wakeup = 0;
650 tty_wakeup(tty);
652 bail:
653 spin_unlock_irqrestore(&hp->lock, flags);
655 if (read_total) {
656 /* Activity is occurring, so reset the polling backoff value to
657 a minimum for performance. */
658 timeout = MIN_TIMEOUT;
660 tty_flip_buffer_push(tty);
663 return poll_mask;
666 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
667 extern cpumask_t cpus_in_xmon;
668 #else
669 static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
670 #endif
673 * This kthread is either polling or interrupt driven. This is determined by
674 * calling hvc_poll() who determines whether a console adapter support
675 * interrupts.
677 static int khvcd(void *unused)
679 int poll_mask;
680 struct hvc_struct *hp;
682 set_freezable();
683 __set_current_state(TASK_RUNNING);
684 do {
685 poll_mask = 0;
686 hvc_kicked = 0;
687 try_to_freeze();
688 wmb();
689 if (cpus_empty(cpus_in_xmon)) {
690 spin_lock(&hvc_structs_lock);
691 list_for_each_entry(hp, &hvc_structs, next) {
692 poll_mask |= hvc_poll(hp);
694 spin_unlock(&hvc_structs_lock);
695 } else
696 poll_mask |= HVC_POLL_READ;
697 if (hvc_kicked)
698 continue;
699 if (poll_mask & HVC_POLL_WRITE) {
700 yield();
701 continue;
703 set_current_state(TASK_INTERRUPTIBLE);
704 if (!hvc_kicked) {
705 if (poll_mask == 0)
706 schedule();
707 else {
708 if (timeout < MAX_TIMEOUT)
709 timeout += (timeout >> 6) + 1;
711 msleep_interruptible(timeout);
714 __set_current_state(TASK_RUNNING);
715 } while (!kthread_should_stop());
717 return 0;
720 static const struct tty_operations hvc_ops = {
721 .open = hvc_open,
722 .close = hvc_close,
723 .write = hvc_write,
724 .hangup = hvc_hangup,
725 .unthrottle = hvc_unthrottle,
726 .write_room = hvc_write_room,
727 .chars_in_buffer = hvc_chars_in_buffer,
730 /* callback when the kboject ref count reaches zero. */
731 static void destroy_hvc_struct(struct kobject *kobj)
733 struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
734 unsigned long flags;
736 spin_lock(&hvc_structs_lock);
738 spin_lock_irqsave(&hp->lock, flags);
739 list_del(&(hp->next));
740 spin_unlock_irqrestore(&hp->lock, flags);
742 spin_unlock(&hvc_structs_lock);
744 kfree(hp);
747 static struct kobj_type hvc_kobj_type = {
748 .release = destroy_hvc_struct,
751 struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int irq,
752 struct hv_ops *ops, int outbuf_size)
754 struct hvc_struct *hp;
755 int i;
757 hp = kmalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
758 GFP_KERNEL);
759 if (!hp)
760 return ERR_PTR(-ENOMEM);
762 memset(hp, 0x00, sizeof(*hp));
764 hp->vtermno = vtermno;
765 hp->irq = irq;
766 hp->ops = ops;
767 hp->outbuf_size = outbuf_size;
768 hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
770 kobject_init(&hp->kobj);
771 hp->kobj.ktype = &hvc_kobj_type;
773 spin_lock_init(&hp->lock);
774 spin_lock(&hvc_structs_lock);
777 * find index to use:
778 * see if this vterm id matches one registered for console.
780 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
781 if (vtermnos[i] == hp->vtermno &&
782 cons_ops[i] == hp->ops)
783 break;
785 /* no matching slot, just use a counter */
786 if (i >= MAX_NR_HVC_CONSOLES)
787 i = ++last_hvc;
789 hp->index = i;
791 list_add_tail(&(hp->next), &hvc_structs);
792 spin_unlock(&hvc_structs_lock);
794 return hp;
797 int __devexit hvc_remove(struct hvc_struct *hp)
799 unsigned long flags;
800 struct kobject *kobjp;
801 struct tty_struct *tty;
803 spin_lock_irqsave(&hp->lock, flags);
804 tty = hp->tty;
805 kobjp = &hp->kobj;
807 if (hp->index < MAX_NR_HVC_CONSOLES)
808 vtermnos[hp->index] = -1;
810 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
812 spin_unlock_irqrestore(&hp->lock, flags);
815 * We 'put' the instance that was grabbed when the kobject instance
816 * was initialized using kobject_init(). Let the last holder of this
817 * kobject cause it to be removed, which will probably be the tty_hangup
818 * below.
820 kobject_put(kobjp);
823 * This function call will auto chain call hvc_hangup. The tty should
824 * always be valid at this time unless a simultaneous tty close already
825 * cleaned up the hvc_struct.
827 if (tty)
828 tty_hangup(tty);
829 return 0;
832 /* Driver initialization. Follow console initialization. This is where the TTY
833 * interfaces start to become available. */
834 static int __init hvc_init(void)
836 struct tty_driver *drv;
838 /* We need more than hvc_count adapters due to hotplug additions. */
839 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
840 if (!drv)
841 return -ENOMEM;
843 drv->owner = THIS_MODULE;
844 drv->driver_name = "hvc";
845 drv->name = "hvc";
846 drv->major = HVC_MAJOR;
847 drv->minor_start = HVC_MINOR;
848 drv->type = TTY_DRIVER_TYPE_SYSTEM;
849 drv->init_termios = tty_std_termios;
850 drv->flags = TTY_DRIVER_REAL_RAW;
851 tty_set_operations(drv, &hvc_ops);
853 /* Always start the kthread because there can be hotplug vty adapters
854 * added later. */
855 hvc_task = kthread_run(khvcd, NULL, "khvcd");
856 if (IS_ERR(hvc_task)) {
857 panic("Couldn't create kthread for console.\n");
858 put_tty_driver(drv);
859 return -EIO;
862 if (tty_register_driver(drv))
863 panic("Couldn't register hvc console driver\n");
865 mb();
866 hvc_driver = drv;
867 return 0;
869 module_init(hvc_init);
871 /* This isn't particularly necessary due to this being a console driver
872 * but it is nice to be thorough.
874 static void __exit hvc_exit(void)
876 kthread_stop(hvc_task);
878 tty_unregister_driver(hvc_driver);
879 /* return tty_struct instances allocated in hvc_init(). */
880 put_tty_driver(hvc_driver);
881 unregister_console(&hvc_con_driver);
883 module_exit(hvc_exit);