[PATCH] hvc_console: Statically initialize the vtermnos array
[linux-2.6] / drivers / char / hvc_console.c
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  */
24
25 #include <linux/config.h>
26 #include <linux/console.h>
27 #include <linux/cpumask.h>
28 #include <linux/init.h>
29 #include <linux/kbd_kern.h>
30 #include <linux/kernel.h>
31 #include <linux/kobject.h>
32 #include <linux/kthread.h>
33 #include <linux/list.h>
34 #include <linux/module.h>
35 #include <linux/major.h>
36 #include <linux/sysrq.h>
37 #include <linux/tty.h>
38 #include <linux/tty_flip.h>
39 #include <linux/sched.h>
40 #include <linux/spinlock.h>
41 #include <linux/delay.h>
42 #include <asm/uaccess.h>
43 #include <asm/hvconsole.h>
44 #include <asm/vio.h>
45
46 #define HVC_MAJOR       229
47 #define HVC_MINOR       0
48
49 #define TIMEOUT         (10)
50
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 */
56
57 /*
58  * The Linux TTY code does not support dynamic addition of tty derived devices
59  * so we need to know how many tty devices we might need when space is allocated
60  * for the tty device.  Since this driver supports hotplug of vty adapters we
61  * need to make sure we have enough allocated.
62  */
63 #define HVC_ALLOC_TTY_ADAPTERS  8
64
65 #define N_OUTBUF        16
66 #define N_INBUF         16
67
68 #define __ALIGNED__     __attribute__((__aligned__(8)))
69
70 static struct tty_driver *hvc_driver;
71 static struct task_struct *hvc_task;
72
73 /* Picks up late kicks after list walk but before schedule() */
74 static int hvc_kicked;
75
76 #ifdef CONFIG_MAGIC_SYSRQ
77 static int sysrq_pressed;
78 #endif
79
80 struct hvc_struct {
81         spinlock_t lock;
82         int index;
83         struct tty_struct *tty;
84         unsigned int count;
85         int do_wakeup;
86         char outbuf[N_OUTBUF] __ALIGNED__;
87         int n_outbuf;
88         uint32_t vtermno;
89         int irq_requested;
90         int irq;
91         struct list_head next;
92         struct kobject kobj; /* ref count & hvc_struct lifetime */
93         struct vio_dev *vdev;
94 };
95
96 /* dynamic list of hvc_struct instances */
97 static struct list_head hvc_structs = LIST_HEAD_INIT(hvc_structs);
98
99 /*
100  * Protect the list of hvc_struct instances from inserts and removals during
101  * list traversal.
102  */
103 static DEFINE_SPINLOCK(hvc_structs_lock);
104
105 /*
106  * This value is used to assign a tty->index value to a hvc_struct based
107  * upon order of exposure via hvc_probe(), when we can not match it to
108  * a console canidate registered with hvc_instantiate().
109  */
110 static int last_hvc = -1;
111
112 /*
113  * Do not call this function with either the hvc_strucst_lock or the hvc_struct
114  * lock held.  If successful, this function increments the kobject reference
115  * count against the target hvc_struct so it should be released when finished.
116  */
117 struct hvc_struct *hvc_get_by_index(int index)
118 {
119         struct hvc_struct *hp;
120         unsigned long flags;
121
122         spin_lock(&hvc_structs_lock);
123
124         list_for_each_entry(hp, &hvc_structs, next) {
125                 spin_lock_irqsave(&hp->lock, flags);
126                 if (hp->index == index) {
127                         kobject_get(&hp->kobj);
128                         spin_unlock_irqrestore(&hp->lock, flags);
129                         spin_unlock(&hvc_structs_lock);
130                         return hp;
131                 }
132                 spin_unlock_irqrestore(&hp->lock, flags);
133         }
134         hp = NULL;
135
136         spin_unlock(&hvc_structs_lock);
137         return hp;
138 }
139
140
141 /*
142  * Initial console vtermnos for console API usage prior to full console
143  * initialization.  Any vty adapter outside this range will not have usable
144  * console interfaces but can still be used as a tty device.  This has to be
145  * static because kmalloc will not work during early console init.
146  */
147 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
148         {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
149
150 /*
151  * Console APIs, NOT TTY.  These APIs are available immediately when
152  * hvc_console_setup() finds adapters.
153  */
154
155 void hvc_console_print(struct console *co, const char *b, unsigned count)
156 {
157         char c[16] __ALIGNED__;
158         unsigned i = 0, n = 0;
159         int r, donecr = 0;
160
161         /* Console access attempt outside of acceptable console range. */
162         if (co->index >= MAX_NR_HVC_CONSOLES)
163                 return;
164
165         /* This console adapter was removed so it is not useable. */
166         if (vtermnos[co->index] < 0)
167                 return;
168
169         while (count > 0 || i > 0) {
170                 if (count > 0 && i < sizeof(c)) {
171                         if (b[n] == '\n' && !donecr) {
172                                 c[i++] = '\r';
173                                 donecr = 1;
174                         } else {
175                                 c[i++] = b[n++];
176                                 donecr = 0;
177                                 --count;
178                         }
179                 } else {
180                         r = hvc_put_chars(vtermnos[co->index], c, i);
181                         if (r < 0) {
182                                 /* throw away chars on error */
183                                 i = 0;
184                         } else if (r > 0) {
185                                 i -= r;
186                                 if (i > 0)
187                                         memmove(c, c+r, i);
188                         }
189                 }
190         }
191 }
192
193 static struct tty_driver *hvc_console_device(struct console *c, int *index)
194 {
195         *index = c->index;
196         return hvc_driver;
197 }
198
199 static int __init hvc_console_setup(struct console *co, char *options)
200 {
201         return 0;
202 }
203
204 struct console hvc_con_driver = {
205         .name           = "hvc",
206         .write          = hvc_console_print,
207         .device         = hvc_console_device,
208         .setup          = hvc_console_setup,
209         .flags          = CON_PRINTBUFFER,
210         .index          = -1,
211 };
212
213 /* Early console initialization.  Preceeds driver initialization. */
214 static int __init hvc_console_init(void)
215 {
216         hvc_find_vtys();
217         register_console(&hvc_con_driver);
218         return 0;
219 }
220 console_initcall(hvc_console_init);
221
222 /*
223  * hvc_instantiate() is an early console discovery method which locates
224  * consoles * prior to the vio subsystem discovering them.  Hotplugged
225  * vty adapters do NOT get an hvc_instantiate() callback since they
226  * appear after early console init.
227  */
228 int hvc_instantiate(uint32_t vtermno, int index)
229 {
230         if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
231                 return -1;
232
233         if (vtermnos[index] != -1)
234                 return -1;
235
236         vtermnos[index] = vtermno;
237
238         /* reserve all indices upto and including this index */
239         if (last_hvc < index)
240                 last_hvc = index;
241
242         return 0;
243 }
244
245 /* Wake the sleeping khvcd */
246 static void hvc_kick(void)
247 {
248         hvc_kicked = 1;
249         wake_up_process(hvc_task);
250 }
251
252 static int hvc_poll(struct hvc_struct *hp);
253
254 /*
255  * NOTE: This API isn't used if the console adapter doesn't support interrupts.
256  * In this case the console is poll driven.
257  */
258 static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance, struct pt_regs *regs)
259 {
260         /* if hvc_poll request a repoll, then kick the hvcd thread */
261         if (hvc_poll(dev_instance))
262                 hvc_kick();
263         return IRQ_HANDLED;
264 }
265
266 static void hvc_unthrottle(struct tty_struct *tty)
267 {
268         hvc_kick();
269 }
270
271 /*
272  * The TTY interface won't be used until after the vio layer has exposed the vty
273  * adapter to the kernel.
274  */
275 static int hvc_open(struct tty_struct *tty, struct file * filp)
276 {
277         struct hvc_struct *hp;
278         unsigned long flags;
279         int irq = NO_IRQ;
280         int rc = 0;
281         struct kobject *kobjp;
282
283         /* Auto increments kobject reference if found. */
284         if (!(hp = hvc_get_by_index(tty->index))) {
285                 printk(KERN_WARNING "hvc_console: tty open failed, no vty associated with tty.\n");
286                 return -ENODEV;
287         }
288
289         spin_lock_irqsave(&hp->lock, flags);
290         /* Check and then increment for fast path open. */
291         if (hp->count++ > 0) {
292                 spin_unlock_irqrestore(&hp->lock, flags);
293                 hvc_kick();
294                 return 0;
295         } /* else count == 0 */
296
297         tty->driver_data = hp;
298         hp->tty = tty;
299         /* Save for request_irq outside of spin_lock. */
300         irq = hp->irq;
301         if (irq != NO_IRQ)
302                 hp->irq_requested = 1;
303
304         kobjp = &hp->kobj;
305
306         spin_unlock_irqrestore(&hp->lock, flags);
307         /* check error, fallback to non-irq */
308         if (irq != NO_IRQ)
309                 rc = request_irq(irq, hvc_handle_interrupt, SA_INTERRUPT, "hvc_console", hp);
310
311         /*
312          * If the request_irq() fails and we return an error.  The tty layer
313          * will call hvc_close() after a failed open but we don't want to clean
314          * up there so we'll clean up here and clear out the previously set
315          * tty fields and return the kobject reference.
316          */
317         if (rc) {
318                 spin_lock_irqsave(&hp->lock, flags);
319                 hp->tty = NULL;
320                 hp->irq_requested = 0;
321                 spin_unlock_irqrestore(&hp->lock, flags);
322                 tty->driver_data = NULL;
323                 kobject_put(kobjp);
324                 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
325         }
326         /* Force wakeup of the polling thread */
327         hvc_kick();
328
329         return rc;
330 }
331
332 static void hvc_close(struct tty_struct *tty, struct file * filp)
333 {
334         struct hvc_struct *hp;
335         struct kobject *kobjp;
336         int irq = NO_IRQ;
337         unsigned long flags;
338
339         if (tty_hung_up_p(filp))
340                 return;
341
342         /*
343          * No driver_data means that this close was issued after a failed
344          * hvc_open by the tty layer's release_dev() function and we can just
345          * exit cleanly because the kobject reference wasn't made.
346          */
347         if (!tty->driver_data)
348                 return;
349
350         hp = tty->driver_data;
351         spin_lock_irqsave(&hp->lock, flags);
352
353         kobjp = &hp->kobj;
354         if (--hp->count == 0) {
355                 if (hp->irq_requested)
356                         irq = hp->irq;
357                 hp->irq_requested = 0;
358
359                 /* We are done with the tty pointer now. */
360                 hp->tty = NULL;
361                 spin_unlock_irqrestore(&hp->lock, flags);
362
363                 /*
364                  * Chain calls chars_in_buffer() and returns immediately if
365                  * there is no buffered data otherwise sleeps on a wait queue
366                  * waking periodically to check chars_in_buffer().
367                  */
368                 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
369
370                 if (irq != NO_IRQ)
371                         free_irq(irq, hp);
372
373         } else {
374                 if (hp->count < 0)
375                         printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
376                                 hp->vtermno, hp->count);
377                 spin_unlock_irqrestore(&hp->lock, flags);
378         }
379
380         kobject_put(kobjp);
381 }
382
383 static void hvc_hangup(struct tty_struct *tty)
384 {
385         struct hvc_struct *hp = tty->driver_data;
386         unsigned long flags;
387         int irq = NO_IRQ;
388         int temp_open_count;
389         struct kobject *kobjp;
390
391         if (!hp)
392                 return;
393
394         spin_lock_irqsave(&hp->lock, flags);
395
396         /*
397          * The N_TTY line discipline has problems such that in a close vs
398          * open->hangup case this can be called after the final close so prevent
399          * that from happening for now.
400          */
401         if (hp->count <= 0) {
402                 spin_unlock_irqrestore(&hp->lock, flags);
403                 return;
404         }
405
406         kobjp = &hp->kobj;
407         temp_open_count = hp->count;
408         hp->count = 0;
409         hp->n_outbuf = 0;
410         hp->tty = NULL;
411         if (hp->irq_requested)
412                 /* Saved for use outside of spin_lock. */
413                 irq = hp->irq;
414         hp->irq_requested = 0;
415         spin_unlock_irqrestore(&hp->lock, flags);
416         if (irq != NO_IRQ)
417                 free_irq(irq, hp);
418         while(temp_open_count) {
419                 --temp_open_count;
420                 kobject_put(kobjp);
421         }
422 }
423
424 /*
425  * Push buffered characters whether they were just recently buffered or waiting
426  * on a blocked hypervisor.  Call this function with hp->lock held.
427  */
428 static void hvc_push(struct hvc_struct *hp)
429 {
430         int n;
431
432         n = hvc_put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
433         if (n <= 0) {
434                 if (n == 0)
435                         return;
436                 /* throw away output on error; this happens when
437                    there is no session connected to the vterm. */
438                 hp->n_outbuf = 0;
439         } else
440                 hp->n_outbuf -= n;
441         if (hp->n_outbuf > 0)
442                 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
443         else
444                 hp->do_wakeup = 1;
445 }
446
447 static inline int __hvc_write_kernel(struct hvc_struct *hp,
448                                    const unsigned char *buf, int count)
449 {
450         unsigned long flags;
451         int rsize, written = 0;
452
453         spin_lock_irqsave(&hp->lock, flags);
454
455         /* Push pending writes */
456         if (hp->n_outbuf > 0)
457                 hvc_push(hp);
458
459         while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) {
460                 if (rsize > count)
461                         rsize = count;
462                 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
463                 count -= rsize;
464                 buf += rsize;
465                 hp->n_outbuf += rsize;
466                 written += rsize;
467                 hvc_push(hp);
468         }
469         spin_unlock_irqrestore(&hp->lock, flags);
470
471         return written;
472 }
473 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
474 {
475         struct hvc_struct *hp = tty->driver_data;
476         int written;
477
478         /* This write was probably executed during a tty close. */
479         if (!hp)
480                 return -EPIPE;
481
482         if (hp->count <= 0)
483                 return -EIO;
484
485         written = __hvc_write_kernel(hp, buf, count);
486
487         /*
488          * Racy, but harmless, kick thread if there is still pending data.
489          * There really is nothing wrong with kicking the thread, even if there
490          * is no buffered data.
491          */
492         if (hp->n_outbuf)
493                 hvc_kick();
494
495         return written;
496 }
497
498 /*
499  * This is actually a contract between the driver and the tty layer outlining
500  * how much write room the driver can guarentee will be sent OR BUFFERED.  This
501  * driver MUST honor the return value.
502  */
503 static int hvc_write_room(struct tty_struct *tty)
504 {
505         struct hvc_struct *hp = tty->driver_data;
506
507         if (!hp)
508                 return -1;
509
510         return N_OUTBUF - hp->n_outbuf;
511 }
512
513 static int hvc_chars_in_buffer(struct tty_struct *tty)
514 {
515         struct hvc_struct *hp = tty->driver_data;
516
517         if (!hp)
518                 return -1;
519         return hp->n_outbuf;
520 }
521
522 #define HVC_POLL_READ   0x00000001
523 #define HVC_POLL_WRITE  0x00000002
524 #define HVC_POLL_QUICK  0x00000004
525
526 static int hvc_poll(struct hvc_struct *hp)
527 {
528         struct tty_struct *tty;
529         int i, n, poll_mask = 0;
530         char buf[N_INBUF] __ALIGNED__;
531         unsigned long flags;
532         int read_total = 0;
533
534         spin_lock_irqsave(&hp->lock, flags);
535
536         /* Push pending writes */
537         if (hp->n_outbuf > 0)
538                 hvc_push(hp);
539         /* Reschedule us if still some write pending */
540         if (hp->n_outbuf > 0)
541                 poll_mask |= HVC_POLL_WRITE;
542
543         /* No tty attached, just skip */
544         tty = hp->tty;
545         if (tty == NULL)
546                 goto bail;
547
548         /* Now check if we can get data (are we throttled ?) */
549         if (test_bit(TTY_THROTTLED, &tty->flags))
550                 goto throttled;
551
552         /* If we aren't interrupt driven and aren't throttled, we always
553          * request a reschedule
554          */
555         if (hp->irq == NO_IRQ)
556                 poll_mask |= HVC_POLL_READ;
557
558         /* Read data if any */
559         for (;;) {
560                 int count = N_INBUF;
561                 if (count > (TTY_FLIPBUF_SIZE - tty->flip.count))
562                         count = TTY_FLIPBUF_SIZE - tty->flip.count;
563
564                 /* If flip is full, just reschedule a later read */
565                 if (count == 0) {
566                         poll_mask |= HVC_POLL_READ;
567                         break;
568                 }
569
570                 n = hvc_get_chars(hp->vtermno, buf, count);
571                 if (n <= 0) {
572                         /* Hangup the tty when disconnected from host */
573                         if (n == -EPIPE) {
574                                 spin_unlock_irqrestore(&hp->lock, flags);
575                                 tty_hangup(tty);
576                                 spin_lock_irqsave(&hp->lock, flags);
577                         }
578                         break;
579                 }
580                 for (i = 0; i < n; ++i) {
581 #ifdef CONFIG_MAGIC_SYSRQ
582                         if (hp->index == hvc_con_driver.index) {
583                                 /* Handle the SysRq Hack */
584                                 /* XXX should support a sequence */
585                                 if (buf[i] == '\x0f') { /* ^O */
586                                         sysrq_pressed = 1;
587                                         continue;
588                                 } else if (sysrq_pressed) {
589                                         handle_sysrq(buf[i], NULL, tty);
590                                         sysrq_pressed = 0;
591                                         continue;
592                                 }
593                         }
594 #endif /* CONFIG_MAGIC_SYSRQ */
595                         tty_insert_flip_char(tty, buf[i], 0);
596                 }
597
598                 if (tty->flip.count)
599                         tty_schedule_flip(tty);
600
601                 /*
602                  * Account for the total amount read in one loop, and if above
603                  * 64 bytes, we do a quick schedule loop to let the tty grok
604                  * the data and eventually throttle us.
605                  */
606                 read_total += n;
607                 if (read_total >= 64) {
608                         poll_mask |= HVC_POLL_QUICK;
609                         break;
610                 }
611         }
612  throttled:
613         /* Wakeup write queue if necessary */
614         if (hp->do_wakeup) {
615                 hp->do_wakeup = 0;
616                 tty_wakeup(tty);
617         }
618  bail:
619         spin_unlock_irqrestore(&hp->lock, flags);
620
621         return poll_mask;
622 }
623
624 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
625 extern cpumask_t cpus_in_xmon;
626 #else
627 static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
628 #endif
629
630 /*
631  * This kthread is either polling or interrupt driven.  This is determined by
632  * calling hvc_poll() who determines whether a console adapter support
633  * interrupts.
634  */
635 int khvcd(void *unused)
636 {
637         int poll_mask;
638         struct hvc_struct *hp;
639
640         __set_current_state(TASK_RUNNING);
641         do {
642                 poll_mask = 0;
643                 hvc_kicked = 0;
644                 wmb();
645                 if (cpus_empty(cpus_in_xmon)) {
646                         spin_lock(&hvc_structs_lock);
647                         list_for_each_entry(hp, &hvc_structs, next) {
648                                 poll_mask |= hvc_poll(hp);
649                         }
650                         spin_unlock(&hvc_structs_lock);
651                 } else
652                         poll_mask |= HVC_POLL_READ;
653                 if (hvc_kicked)
654                         continue;
655                 if (poll_mask & HVC_POLL_QUICK) {
656                         yield();
657                         continue;
658                 }
659                 set_current_state(TASK_INTERRUPTIBLE);
660                 if (!hvc_kicked) {
661                         if (poll_mask == 0)
662                                 schedule();
663                         else
664                                 msleep_interruptible(TIMEOUT);
665                 }
666                 __set_current_state(TASK_RUNNING);
667         } while (!kthread_should_stop());
668
669         return 0;
670 }
671
672 static struct tty_operations hvc_ops = {
673         .open = hvc_open,
674         .close = hvc_close,
675         .write = hvc_write,
676         .hangup = hvc_hangup,
677         .unthrottle = hvc_unthrottle,
678         .write_room = hvc_write_room,
679         .chars_in_buffer = hvc_chars_in_buffer,
680 };
681
682 /* callback when the kboject ref count reaches zero. */
683 static void destroy_hvc_struct(struct kobject *kobj)
684 {
685         struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
686         unsigned long flags;
687
688         spin_lock(&hvc_structs_lock);
689
690         spin_lock_irqsave(&hp->lock, flags);
691         list_del(&(hp->next));
692         spin_unlock_irqrestore(&hp->lock, flags);
693
694         spin_unlock(&hvc_structs_lock);
695
696         kfree(hp);
697 }
698
699 static struct kobj_type hvc_kobj_type = {
700         .release = destroy_hvc_struct,
701 };
702
703 static int __devinit hvc_probe(
704                 struct vio_dev *dev,
705                 const struct vio_device_id *id)
706 {
707         struct hvc_struct *hp;
708         int i;
709
710         /* probed with invalid parameters. */
711         if (!dev || !id)
712                 return -EPERM;
713
714         hp = kmalloc(sizeof(*hp), GFP_KERNEL);
715         if (!hp)
716                 return -ENOMEM;
717
718         memset(hp, 0x00, sizeof(*hp));
719         hp->vtermno = dev->unit_address;
720         hp->vdev = dev;
721         hp->vdev->dev.driver_data = hp;
722         hp->irq = dev->irq;
723
724         kobject_init(&hp->kobj);
725         hp->kobj.ktype = &hvc_kobj_type;
726
727         spin_lock_init(&hp->lock);
728         spin_lock(&hvc_structs_lock);
729
730         /*
731          * find index to use:
732          * see if this vterm id matches one registered for console.
733          */
734         for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
735                 if (vtermnos[i] == hp->vtermno)
736                         break;
737
738         /* no matching slot, just use a counter */
739         if (i >= MAX_NR_HVC_CONSOLES)
740                 i = ++last_hvc;
741
742         hp->index = i;
743
744         list_add_tail(&(hp->next), &hvc_structs);
745         spin_unlock(&hvc_structs_lock);
746
747         return 0;
748 }
749
750 static int __devexit hvc_remove(struct vio_dev *dev)
751 {
752         struct hvc_struct *hp = dev->dev.driver_data;
753         unsigned long flags;
754         struct kobject *kobjp;
755         struct tty_struct *tty;
756
757         spin_lock_irqsave(&hp->lock, flags);
758         tty = hp->tty;
759         kobjp = &hp->kobj;
760
761         if (hp->index < MAX_NR_HVC_CONSOLES)
762                 vtermnos[hp->index] = -1;
763
764         /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
765
766         spin_unlock_irqrestore(&hp->lock, flags);
767
768         /*
769          * We 'put' the instance that was grabbed when the kobject instance
770          * was intialized using kobject_init().  Let the last holder of this
771          * kobject cause it to be removed, which will probably be the tty_hangup
772          * below.
773          */
774         kobject_put(kobjp);
775
776         /*
777          * This function call will auto chain call hvc_hangup.  The tty should
778          * always be valid at this time unless a simultaneous tty close already
779          * cleaned up the hvc_struct.
780          */
781         if (tty)
782                 tty_hangup(tty);
783         return 0;
784 }
785
786 char hvc_driver_name[] = "hvc_console";
787
788 static struct vio_device_id hvc_driver_table[] __devinitdata= {
789         {"serial", "hvterm1"},
790         { NULL, }
791 };
792 MODULE_DEVICE_TABLE(vio, hvc_driver_table);
793
794 static struct vio_driver hvc_vio_driver = {
795         .name           = hvc_driver_name,
796         .id_table       = hvc_driver_table,
797         .probe          = hvc_probe,
798         .remove         = hvc_remove,
799 };
800
801 /* Driver initialization.  Follow console initialization.  This is where the TTY
802  * interfaces start to become available. */
803 int __init hvc_init(void)
804 {
805         int rc;
806
807         /* We need more than hvc_count adapters due to hotplug additions. */
808         hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
809         if (!hvc_driver)
810                 return -ENOMEM;
811
812         hvc_driver->owner = THIS_MODULE;
813         hvc_driver->devfs_name = "hvc/";
814         hvc_driver->driver_name = "hvc";
815         hvc_driver->name = "hvc";
816         hvc_driver->major = HVC_MAJOR;
817         hvc_driver->minor_start = HVC_MINOR;
818         hvc_driver->type = TTY_DRIVER_TYPE_SYSTEM;
819         hvc_driver->init_termios = tty_std_termios;
820         hvc_driver->flags = TTY_DRIVER_REAL_RAW;
821         tty_set_operations(hvc_driver, &hvc_ops);
822
823         if (tty_register_driver(hvc_driver))
824                 panic("Couldn't register hvc console driver\n");
825
826         /* Always start the kthread because there can be hotplug vty adapters
827          * added later. */
828         hvc_task = kthread_run(khvcd, NULL, "khvcd");
829         if (IS_ERR(hvc_task)) {
830                 panic("Couldn't create kthread for console.\n");
831                 put_tty_driver(hvc_driver);
832                 return -EIO;
833         }
834
835         /* Register as a vio device to receive callbacks */
836         rc = vio_register_driver(&hvc_vio_driver);
837
838         return rc;
839 }
840 module_init(hvc_init);
841
842 /* This isn't particularily necessary due to this being a console driver
843  * but it is nice to be thorough.
844  */
845 static void __exit hvc_exit(void)
846 {
847         kthread_stop(hvc_task);
848
849         vio_unregister_driver(&hvc_vio_driver);
850         tty_unregister_driver(hvc_driver);
851         /* return tty_struct instances allocated in hvc_init(). */
852         put_tty_driver(hvc_driver);
853         unregister_console(&hvc_con_driver);
854 }
855 module_exit(hvc_exit);