ia64/linux-2.6.18-xen.hg

view drivers/char/hvc_console.c @ 893:f994bfe9b93b

linux/blktap2: reduce TLB flush scope

c/s 885 added very coarse TLB flushing. Since these flushes always
follow single page updates, single page flushes (when available) are
sufficient.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
author Keir Fraser <keir.fraser@citrix.com>
date Thu Jun 04 10:32:57 2009 +0100 (2009-06-04)
parents 831230e53067
children
line source
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
6 *
7 * Additional Author(s):
8 * Ryan S. Arnold <rsa@us.ibm.com>
9 *
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.
14 *
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.
19 *
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
23 */
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>
42 #include <asm/uaccess.h>
44 #include "hvc_console.h"
46 #define HVC_MAJOR 229
47 #define HVC_MINOR 0
49 #define TIMEOUT (10)
51 /*
52 * Wait this long per iteration while trying to push buffered data to the
53 * hypervisor before allowing the tty to complete a close operation.
54 */
55 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
57 /*
58 * These sizes are most efficient for vio, because they are the
59 * native transfer size. We could make them selectable in the
60 * future to better deal with backends that want other buffer sizes.
61 */
62 #define N_OUTBUF 16
63 #define N_INBUF 16
65 #define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
67 static struct tty_driver *hvc_driver;
68 static struct task_struct *hvc_task;
70 /* Picks up late kicks after list walk but before schedule() */
71 static int hvc_kicked;
73 #ifdef CONFIG_MAGIC_SYSRQ
74 static int sysrq_pressed;
75 #endif
77 struct hvc_struct {
78 spinlock_t lock;
79 int index;
80 struct tty_struct *tty;
81 unsigned int count;
82 int do_wakeup;
83 char outbuf[N_OUTBUF] __ALIGNED__;
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 */
91 };
93 /* dynamic list of hvc_struct instances */
94 static struct list_head hvc_structs = LIST_HEAD_INIT(hvc_structs);
96 /*
97 * Protect the list of hvc_struct instances from inserts and removals during
98 * list traversal.
99 */
100 static DEFINE_SPINLOCK(hvc_structs_lock);
102 /*
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 canidate registered with hvc_instantiate().
106 */
107 static int last_hvc = -1;
109 /*
110 * Do not call this function with either the hvc_strucst_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.
113 */
114 struct hvc_struct *hvc_get_by_index(int index)
115 {
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;
128 }
129 spin_unlock_irqrestore(&hp->lock, flags);
130 }
131 hp = NULL;
133 spin_unlock(&hvc_structs_lock);
134 return hp;
135 }
138 /*
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.
143 */
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};
148 /*
149 * Console APIs, NOT TTY. These APIs are available immediately when
150 * hvc_console_setup() finds adapters.
151 */
153 void hvc_console_print(struct console *co, const char *b, unsigned count)
154 {
155 char c[N_OUTBUF] __ALIGNED__;
156 unsigned i = 0, n = 0;
157 int r, donecr = 0, index = co->index;
159 /* Console access attempt outside of acceptable console range. */
160 if (index >= MAX_NR_HVC_CONSOLES)
161 return;
163 /* This console adapter was removed so it is not useable. */
164 if (vtermnos[index] < 0)
165 return;
167 while (count > 0 || i > 0) {
168 if (count > 0 && i < sizeof(c)) {
169 if (b[n] == '\n' && !donecr) {
170 c[i++] = '\r';
171 donecr = 1;
172 } else {
173 c[i++] = b[n++];
174 donecr = 0;
175 --count;
176 }
177 } else {
178 r = cons_ops[index]->put_chars(vtermnos[index], c, i);
179 if (r < 0) {
180 /* throw away chars on error */
181 i = 0;
182 } else if (r > 0) {
183 i -= r;
184 if (i > 0)
185 memmove(c, c+r, i);
186 }
187 }
188 }
189 }
191 static struct tty_driver *hvc_console_device(struct console *c, int *index)
192 {
193 if (vtermnos[c->index] == -1)
194 return NULL;
196 *index = c->index;
197 return hvc_driver;
198 }
200 static int __init hvc_console_setup(struct console *co, char *options)
201 {
202 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
203 return -ENODEV;
205 if (vtermnos[co->index] == -1)
206 return -ENODEV;
208 return 0;
209 }
211 struct console hvc_con_driver = {
212 .name = "hvc",
213 .write = hvc_console_print,
214 .device = hvc_console_device,
215 .setup = hvc_console_setup,
216 .flags = CON_PRINTBUFFER,
217 .index = -1,
218 };
220 /*
221 * Early console initialization. Preceeds driver initialization.
222 *
223 * (1) we are first, and the user specified another driver
224 * -- index will remain -1
225 * (2) we are first and the user specified no driver
226 * -- index will be set to 0, then we will fail setup.
227 * (3) we are first and the user specified our driver
228 * -- index will be set to user specified driver, and we will fail
229 * (4) we are after driver, and this initcall will register us
230 * -- if the user didn't specify a driver then the console will match
231 *
232 * Note that for cases 2 and 3, we will match later when the io driver
233 * calls hvc_instantiate() and call register again.
234 */
235 static int __init hvc_console_init(void)
236 {
237 register_console(&hvc_con_driver);
238 return 0;
239 }
240 console_initcall(hvc_console_init);
242 /*
243 * hvc_instantiate() is an early console discovery method which locates
244 * consoles * prior to the vio subsystem discovering them. Hotplugged
245 * vty adapters do NOT get an hvc_instantiate() callback since they
246 * appear after early console init.
247 */
248 int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops)
249 {
250 struct hvc_struct *hp;
252 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
253 return -1;
255 if (vtermnos[index] != -1)
256 return -1;
258 /* make sure no no tty has been registerd in this index */
259 hp = hvc_get_by_index(index);
260 if (hp) {
261 kobject_put(&hp->kobj);
262 return -1;
263 }
265 vtermnos[index] = vtermno;
266 cons_ops[index] = ops;
268 /* reserve all indices upto and including this index */
269 if (last_hvc < index)
270 last_hvc = index;
272 /* if this index is what the user requested, then register
273 * now (setup won't fail at this point). It's ok to just
274 * call register again if previously .setup failed.
275 */
276 if (index == hvc_con_driver.index)
277 register_console(&hvc_con_driver);
279 return 0;
280 }
281 EXPORT_SYMBOL(hvc_instantiate);
283 /* Wake the sleeping khvcd */
284 static void hvc_kick(void)
285 {
286 hvc_kicked = 1;
287 wake_up_process(hvc_task);
288 }
290 static int hvc_poll(struct hvc_struct *hp);
292 /*
293 * NOTE: This API isn't used if the console adapter doesn't support interrupts.
294 * In this case the console is poll driven.
295 */
296 static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance, struct pt_regs *regs)
297 {
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;
302 }
304 static void hvc_unthrottle(struct tty_struct *tty)
305 {
306 hvc_kick();
307 }
309 /*
310 * The TTY interface won't be used until after the vio layer has exposed the vty
311 * adapter to the kernel.
312 */
313 static int hvc_open(struct tty_struct *tty, struct file * filp)
314 {
315 struct hvc_struct *hp;
316 unsigned long flags;
317 int irq = NO_IRQ;
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 printk(KERN_WARNING "hvc_console: tty open failed, no vty associated with tty.\n");
324 return -ENODEV;
325 }
327 spin_lock_irqsave(&hp->lock, flags);
328 /* Check and then increment for fast path open. */
329 if (hp->count++ > 0) {
330 spin_unlock_irqrestore(&hp->lock, flags);
331 hvc_kick();
332 return 0;
333 } /* else count == 0 */
335 tty->driver_data = hp;
336 tty->low_latency = 1; /* Makes flushes to ldisc synchronous. */
338 hp->tty = tty;
339 /* Save for request_irq outside of spin_lock. */
340 irq = hp->irq;
341 if (irq != NO_IRQ)
342 hp->irq_requested = 1;
344 kobjp = &hp->kobj;
346 spin_unlock_irqrestore(&hp->lock, flags);
347 /* check error, fallback to non-irq */
348 if (irq != NO_IRQ)
349 rc = request_irq(irq, hvc_handle_interrupt, IRQF_DISABLED, "hvc_console", hp);
351 /*
352 * If the request_irq() fails and we return an error. The tty layer
353 * will call hvc_close() after a failed open but we don't want to clean
354 * up there so we'll clean up here and clear out the previously set
355 * tty fields and return the kobject reference.
356 */
357 if (rc) {
358 spin_lock_irqsave(&hp->lock, flags);
359 hp->tty = NULL;
360 hp->irq_requested = 0;
361 spin_unlock_irqrestore(&hp->lock, flags);
362 tty->driver_data = NULL;
363 kobject_put(kobjp);
364 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
365 }
366 /* Force wakeup of the polling thread */
367 hvc_kick();
369 return rc;
370 }
372 static void hvc_close(struct tty_struct *tty, struct file * filp)
373 {
374 struct hvc_struct *hp;
375 struct kobject *kobjp;
376 int irq = NO_IRQ;
377 unsigned long flags;
379 if (tty_hung_up_p(filp))
380 return;
382 /*
383 * No driver_data means that this close was issued after a failed
384 * hvc_open by the tty layer's release_dev() function and we can just
385 * exit cleanly because the kobject reference wasn't made.
386 */
387 if (!tty->driver_data)
388 return;
390 hp = tty->driver_data;
391 spin_lock_irqsave(&hp->lock, flags);
393 kobjp = &hp->kobj;
394 if (--hp->count == 0) {
395 if (hp->irq_requested)
396 irq = hp->irq;
397 hp->irq_requested = 0;
399 /* We are done with the tty pointer now. */
400 hp->tty = NULL;
401 spin_unlock_irqrestore(&hp->lock, flags);
403 /*
404 * Chain calls chars_in_buffer() and returns immediately if
405 * there is no buffered data otherwise sleeps on a wait queue
406 * waking periodically to check chars_in_buffer().
407 */
408 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
410 if (irq != NO_IRQ)
411 free_irq(irq, hp);
413 } else {
414 if (hp->count < 0)
415 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
416 hp->vtermno, hp->count);
417 spin_unlock_irqrestore(&hp->lock, flags);
418 }
420 kobject_put(kobjp);
421 }
423 static void hvc_hangup(struct tty_struct *tty)
424 {
425 struct hvc_struct *hp = tty->driver_data;
426 unsigned long flags;
427 int irq = NO_IRQ;
428 int temp_open_count;
429 struct kobject *kobjp;
431 if (!hp)
432 return;
434 spin_lock_irqsave(&hp->lock, flags);
436 /*
437 * The N_TTY line discipline has problems such that in a close vs
438 * open->hangup case this can be called after the final close so prevent
439 * that from happening for now.
440 */
441 if (hp->count <= 0) {
442 spin_unlock_irqrestore(&hp->lock, flags);
443 return;
444 }
446 kobjp = &hp->kobj;
447 temp_open_count = hp->count;
448 hp->count = 0;
449 hp->n_outbuf = 0;
450 hp->tty = NULL;
451 if (hp->irq_requested)
452 /* Saved for use outside of spin_lock. */
453 irq = hp->irq;
454 hp->irq_requested = 0;
455 spin_unlock_irqrestore(&hp->lock, flags);
456 if (irq != NO_IRQ)
457 free_irq(irq, hp);
458 while(temp_open_count) {
459 --temp_open_count;
460 kobject_put(kobjp);
461 }
462 }
464 /*
465 * Push buffered characters whether they were just recently buffered or waiting
466 * on a blocked hypervisor. Call this function with hp->lock held.
467 */
468 static void hvc_push(struct hvc_struct *hp)
469 {
470 int n;
472 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
473 if (n <= 0) {
474 if (n == 0) {
475 hp->do_wakeup = 1;
476 return;
477 }
478 /* throw away output on error; this happens when
479 there is no session connected to the vterm. */
480 hp->n_outbuf = 0;
481 } else
482 hp->n_outbuf -= n;
483 if (hp->n_outbuf > 0)
484 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
485 else
486 hp->do_wakeup = 1;
487 }
489 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
490 {
491 struct hvc_struct *hp = tty->driver_data;
492 unsigned long flags;
493 int rsize, written = 0;
495 /* This write was probably executed during a tty close. */
496 if (!hp)
497 return -EPIPE;
499 if (hp->count <= 0)
500 return -EIO;
502 spin_lock_irqsave(&hp->lock, flags);
504 /* Push pending writes */
505 if (hp->n_outbuf > 0)
506 hvc_push(hp);
508 while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) {
509 if (rsize > count)
510 rsize = count;
511 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
512 count -= rsize;
513 buf += rsize;
514 hp->n_outbuf += rsize;
515 written += rsize;
516 hvc_push(hp);
517 }
518 spin_unlock_irqrestore(&hp->lock, flags);
520 /*
521 * Racy, but harmless, kick thread if there is still pending data.
522 */
523 if (hp->n_outbuf)
524 hvc_kick();
526 return written;
527 }
529 /*
530 * This is actually a contract between the driver and the tty layer outlining
531 * how much write room the driver can guarentee will be sent OR BUFFERED. This
532 * driver MUST honor the return value.
533 */
534 static int hvc_write_room(struct tty_struct *tty)
535 {
536 struct hvc_struct *hp = tty->driver_data;
538 if (!hp)
539 return -1;
541 return N_OUTBUF - hp->n_outbuf;
542 }
544 static int hvc_chars_in_buffer(struct tty_struct *tty)
545 {
546 struct hvc_struct *hp = tty->driver_data;
548 if (!hp)
549 return -1;
550 return hp->n_outbuf;
551 }
553 #define HVC_POLL_READ 0x00000001
554 #define HVC_POLL_WRITE 0x00000002
556 static int hvc_poll(struct hvc_struct *hp)
557 {
558 struct tty_struct *tty;
559 int i, n, poll_mask = 0;
560 char buf[N_INBUF] __ALIGNED__;
561 unsigned long flags;
562 int read_total = 0;
564 spin_lock_irqsave(&hp->lock, flags);
566 /* Push pending writes */
567 if (hp->n_outbuf > 0)
568 hvc_push(hp);
570 /* Reschedule us if still some write pending */
571 if (hp->n_outbuf > 0)
572 poll_mask |= HVC_POLL_WRITE;
574 /* No tty attached, just skip */
575 tty = hp->tty;
576 if (tty == NULL)
577 goto bail;
579 /* Now check if we can get data (are we throttled ?) */
580 if (test_bit(TTY_THROTTLED, &tty->flags))
581 goto throttled;
583 /* If we aren't interrupt driven and aren't throttled, we always
584 * request a reschedule
585 */
586 if (hp->irq == NO_IRQ)
587 poll_mask |= HVC_POLL_READ;
589 /* Read data if any */
590 for (;;) {
591 int count = tty_buffer_request_room(tty, N_INBUF);
593 /* If flip is full, just reschedule a later read */
594 if (count == 0) {
595 poll_mask |= HVC_POLL_READ;
596 break;
597 }
599 n = hp->ops->get_chars(hp->vtermno, buf, count);
600 if (n <= 0) {
601 /* Hangup the tty when disconnected from host */
602 if (n == -EPIPE) {
603 spin_unlock_irqrestore(&hp->lock, flags);
604 tty_hangup(tty);
605 spin_lock_irqsave(&hp->lock, flags);
606 } else if ( n == -EAGAIN ) {
607 /*
608 * Some back-ends can only ensure a certain min
609 * num of bytes read, which may be > 'count'.
610 * Let the tty clear the flip buff to make room.
611 */
612 poll_mask |= HVC_POLL_READ;
613 }
614 break;
615 }
616 for (i = 0; i < n; ++i) {
617 #ifdef CONFIG_MAGIC_SYSRQ
618 if (hp->index == hvc_con_driver.index) {
619 /* Handle the SysRq Hack */
620 /* XXX should support a sequence */
621 if (buf[i] == '\x0f') { /* ^O */
622 sysrq_pressed = 1;
623 continue;
624 } else if (sysrq_pressed) {
625 handle_sysrq(buf[i], NULL, tty);
626 sysrq_pressed = 0;
627 continue;
628 }
629 }
630 #endif /* CONFIG_MAGIC_SYSRQ */
631 tty_insert_flip_char(tty, buf[i], 0);
632 }
634 read_total += n;
635 }
636 throttled:
637 /* Wakeup write queue if necessary */
638 if (hp->do_wakeup) {
639 hp->do_wakeup = 0;
640 tty_wakeup(tty);
641 }
642 bail:
643 spin_unlock_irqrestore(&hp->lock, flags);
645 if (read_total)
646 tty_flip_buffer_push(tty);
648 return poll_mask;
649 }
651 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
652 extern cpumask_t cpus_in_xmon;
653 #else
654 static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
655 #endif
657 /*
658 * This kthread is either polling or interrupt driven. This is determined by
659 * calling hvc_poll() who determines whether a console adapter support
660 * interrupts.
661 */
662 int khvcd(void *unused)
663 {
664 int poll_mask;
665 struct hvc_struct *hp;
667 __set_current_state(TASK_RUNNING);
668 do {
669 poll_mask = 0;
670 hvc_kicked = 0;
671 try_to_freeze();
672 wmb();
673 if (cpus_empty(cpus_in_xmon)) {
674 spin_lock(&hvc_structs_lock);
675 list_for_each_entry(hp, &hvc_structs, next) {
676 poll_mask |= hvc_poll(hp);
677 }
678 spin_unlock(&hvc_structs_lock);
679 } else
680 poll_mask |= HVC_POLL_READ;
681 if (hvc_kicked)
682 continue;
683 if (poll_mask & HVC_POLL_WRITE) {
684 yield();
685 continue;
686 }
687 set_current_state(TASK_INTERRUPTIBLE);
688 if (!hvc_kicked) {
689 if (poll_mask == 0)
690 schedule();
691 else
692 msleep_interruptible(TIMEOUT);
693 }
694 __set_current_state(TASK_RUNNING);
695 } while (!kthread_should_stop());
697 return 0;
698 }
700 static struct tty_operations hvc_ops = {
701 .open = hvc_open,
702 .close = hvc_close,
703 .write = hvc_write,
704 .hangup = hvc_hangup,
705 .unthrottle = hvc_unthrottle,
706 .write_room = hvc_write_room,
707 .chars_in_buffer = hvc_chars_in_buffer,
708 };
710 /* callback when the kboject ref count reaches zero. */
711 static void destroy_hvc_struct(struct kobject *kobj)
712 {
713 struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
714 unsigned long flags;
716 spin_lock(&hvc_structs_lock);
718 spin_lock_irqsave(&hp->lock, flags);
719 list_del(&(hp->next));
720 spin_unlock_irqrestore(&hp->lock, flags);
722 spin_unlock(&hvc_structs_lock);
724 kfree(hp);
725 }
727 static struct kobj_type hvc_kobj_type = {
728 .release = destroy_hvc_struct,
729 };
731 struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int irq,
732 struct hv_ops *ops)
733 {
734 struct hvc_struct *hp;
735 int i;
737 hp = kmalloc(sizeof(*hp), GFP_KERNEL);
738 if (!hp)
739 return ERR_PTR(-ENOMEM);
741 memset(hp, 0x00, sizeof(*hp));
743 hp->vtermno = vtermno;
744 hp->irq = irq;
745 hp->ops = ops;
747 kobject_init(&hp->kobj);
748 hp->kobj.ktype = &hvc_kobj_type;
750 spin_lock_init(&hp->lock);
751 spin_lock(&hvc_structs_lock);
753 /*
754 * find index to use:
755 * see if this vterm id matches one registered for console.
756 */
757 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
758 if (vtermnos[i] == hp->vtermno &&
759 cons_ops[i] == hp->ops)
760 break;
762 /* no matching slot, just use a counter */
763 if (i >= MAX_NR_HVC_CONSOLES)
764 i = ++last_hvc;
766 hp->index = i;
768 list_add_tail(&(hp->next), &hvc_structs);
769 spin_unlock(&hvc_structs_lock);
771 return hp;
772 }
773 EXPORT_SYMBOL(hvc_alloc);
775 int __devexit hvc_remove(struct hvc_struct *hp)
776 {
777 unsigned long flags;
778 struct kobject *kobjp;
779 struct tty_struct *tty;
781 spin_lock_irqsave(&hp->lock, flags);
782 tty = hp->tty;
783 kobjp = &hp->kobj;
785 if (hp->index < MAX_NR_HVC_CONSOLES)
786 vtermnos[hp->index] = -1;
788 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
790 spin_unlock_irqrestore(&hp->lock, flags);
792 /*
793 * We 'put' the instance that was grabbed when the kobject instance
794 * was intialized using kobject_init(). Let the last holder of this
795 * kobject cause it to be removed, which will probably be the tty_hangup
796 * below.
797 */
798 kobject_put(kobjp);
800 /*
801 * This function call will auto chain call hvc_hangup. The tty should
802 * always be valid at this time unless a simultaneous tty close already
803 * cleaned up the hvc_struct.
804 */
805 if (tty)
806 tty_hangup(tty);
807 return 0;
808 }
809 EXPORT_SYMBOL(hvc_remove);
811 /* Driver initialization. Follow console initialization. This is where the TTY
812 * interfaces start to become available. */
813 int __init hvc_init(void)
814 {
815 struct tty_driver *drv;
817 /* We need more than hvc_count adapters due to hotplug additions. */
818 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
819 if (!drv)
820 return -ENOMEM;
822 drv->owner = THIS_MODULE;
823 drv->driver_name = "hvc";
824 drv->name = "hvc";
825 drv->major = HVC_MAJOR;
826 drv->minor_start = HVC_MINOR;
827 drv->type = TTY_DRIVER_TYPE_SYSTEM;
828 drv->init_termios = tty_std_termios;
829 drv->flags = TTY_DRIVER_REAL_RAW;
830 tty_set_operations(drv, &hvc_ops);
832 /* Always start the kthread because there can be hotplug vty adapters
833 * added later. */
834 hvc_task = kthread_run(khvcd, NULL, "khvcd");
835 if (IS_ERR(hvc_task)) {
836 panic("Couldn't create kthread for console.\n");
837 put_tty_driver(drv);
838 return -EIO;
839 }
841 if (tty_register_driver(drv))
842 panic("Couldn't register hvc console driver\n");
844 mb();
845 hvc_driver = drv;
846 return 0;
847 }
848 module_init(hvc_init);
850 /* This isn't particularily necessary due to this being a console driver
851 * but it is nice to be thorough.
852 */
853 static void __exit hvc_exit(void)
854 {
855 kthread_stop(hvc_task);
857 tty_unregister_driver(hvc_driver);
858 /* return tty_struct instances allocated in hvc_init(). */
859 put_tty_driver(hvc_driver);
860 unregister_console(&hvc_con_driver);
861 }
862 module_exit(hvc_exit);