Merge master.kernel.org:/home/rmk/linux-2.6-arm
[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/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 <asm/uaccess.h>
42 #include <asm/hvconsole.h>
43 #include <asm/vio.h>
44
45 #define HVC_MAJOR       229
46 #define HVC_MINOR       0
47
48 #define TIMEOUT         (10)
49
50 /*
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.
53  */
54 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
55
56 /*
57  * The Linux TTY code does not support dynamic addition of tty derived devices
58  * so we need to know how many tty devices we might need when space is allocated
59  * for the tty device.  Since this driver supports hotplug of vty adapters we
60  * need to make sure we have enough allocated.
61  */
62 #define HVC_ALLOC_TTY_ADAPTERS  8
63
64 static struct tty_driver *hvc_driver;
65 #ifdef CONFIG_MAGIC_SYSRQ
66 static int sysrq_pressed;
67 #endif
68
69 #define N_OUTBUF        16
70 #define N_INBUF         16
71
72 #define __ALIGNED__     __attribute__((__aligned__(8)))
73
74 struct hvc_struct {
75         spinlock_t lock;
76         int index;
77         struct tty_struct *tty;
78         unsigned int count;
79         int do_wakeup;
80         char outbuf[N_OUTBUF] __ALIGNED__;
81         int n_outbuf;
82         uint32_t vtermno;
83         int irq_requested;
84         int irq;
85         struct list_head next;
86         struct kobject kobj; /* ref count & hvc_struct lifetime */
87         struct vio_dev *vdev;
88 };
89
90 /* dynamic list of hvc_struct instances */
91 static struct list_head hvc_structs = LIST_HEAD_INIT(hvc_structs);
92
93 /*
94  * Protect the list of hvc_struct instances from inserts and removals during
95  * list traversal.
96  */
97 static DEFINE_SPINLOCK(hvc_structs_lock);
98
99 /*
100  * Initial console vtermnos for console API usage prior to full console
101  * initialization.  Any vty adapter outside this range will not have usable
102  * console interfaces but can still be used as a tty device.  This has to be
103  * static because kmalloc will not work during early console init.
104  */
105 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES];
106
107 /* Used for accounting purposes */
108 static int num_vterms = 0;
109
110 static struct task_struct *hvc_task;
111
112 /*
113  * This value is used to associate a tty->index value to a hvc_struct based
114  * upon order of exposure via hvc_probe().
115  */
116 static int hvc_count = -1;
117
118 /* Picks up late kicks after list walk but before schedule() */
119 static int hvc_kicked;
120
121 /* Wake the sleeping khvcd */
122 static void hvc_kick(void)
123 {
124         hvc_kicked = 1;
125         wake_up_process(hvc_task);
126 }
127
128 /*
129  * NOTE: This API isn't used if the console adapter doesn't support interrupts.
130  * In this case the console is poll driven.
131  */
132 static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance, struct pt_regs *regs)
133 {
134         hvc_kick();
135         return IRQ_HANDLED;
136 }
137
138 static void hvc_unthrottle(struct tty_struct *tty)
139 {
140         hvc_kick();
141 }
142
143 /*
144  * Do not call this function with either the hvc_strucst_lock or the hvc_struct
145  * lock held.  If successful, this function increments the kobject reference
146  * count against the target hvc_struct so it should be released when finished.
147  */
148 struct hvc_struct *hvc_get_by_index(int index)
149 {
150         struct hvc_struct *hp;
151         unsigned long flags;
152
153         spin_lock(&hvc_structs_lock);
154
155         list_for_each_entry(hp, &hvc_structs, next) {
156                 spin_lock_irqsave(&hp->lock, flags);
157                 if (hp->index == index) {
158                         kobject_get(&hp->kobj);
159                         spin_unlock_irqrestore(&hp->lock, flags);
160                         spin_unlock(&hvc_structs_lock);
161                         return hp;
162                 }
163                 spin_unlock_irqrestore(&hp->lock, flags);
164         }
165         hp = NULL;
166
167         spin_unlock(&hvc_structs_lock);
168         return hp;
169 }
170
171 /*
172  * The TTY interface won't be used until after the vio layer has exposed the vty
173  * adapter to the kernel.
174  */
175 static int hvc_open(struct tty_struct *tty, struct file * filp)
176 {
177         struct hvc_struct *hp;
178         unsigned long flags;
179         int irq = NO_IRQ;
180         int rc = 0;
181         struct kobject *kobjp;
182
183         /* Auto increments kobject reference if found. */
184         if (!(hp = hvc_get_by_index(tty->index))) {
185                 printk(KERN_WARNING "hvc_console: tty open failed, no vty associated with tty.\n");
186                 return -ENODEV;
187         }
188
189         spin_lock_irqsave(&hp->lock, flags);
190         /* Check and then increment for fast path open. */
191         if (hp->count++ > 0) {
192                 spin_unlock_irqrestore(&hp->lock, flags);
193                 hvc_kick();
194                 return 0;
195         } /* else count == 0 */
196
197         tty->driver_data = hp;
198         hp->tty = tty;
199         /* Save for request_irq outside of spin_lock. */
200         irq = hp->irq;
201         if (irq != NO_IRQ)
202                 hp->irq_requested = 1;
203
204         kobjp = &hp->kobj;
205
206         spin_unlock_irqrestore(&hp->lock, flags);
207         /* check error, fallback to non-irq */
208         if (irq != NO_IRQ)
209                 rc = request_irq(irq, hvc_handle_interrupt, SA_INTERRUPT, "hvc_console", hp);
210
211         /*
212          * If the request_irq() fails and we return an error.  The tty layer
213          * will call hvc_close() after a failed open but we don't want to clean
214          * up there so we'll clean up here and clear out the previously set
215          * tty fields and return the kobject reference.
216          */
217         if (rc) {
218                 spin_lock_irqsave(&hp->lock, flags);
219                 hp->tty = NULL;
220                 hp->irq_requested = 0;
221                 spin_unlock_irqrestore(&hp->lock, flags);
222                 tty->driver_data = NULL;
223                 kobject_put(kobjp);
224                 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
225         }
226         /* Force wakeup of the polling thread */
227         hvc_kick();
228
229         return rc;
230 }
231
232 static void hvc_close(struct tty_struct *tty, struct file * filp)
233 {
234         struct hvc_struct *hp;
235         struct kobject *kobjp;
236         int irq = NO_IRQ;
237         unsigned long flags;
238
239         if (tty_hung_up_p(filp))
240                 return;
241
242         /*
243          * No driver_data means that this close was issued after a failed
244          * hvc_open by the tty layer's release_dev() function and we can just
245          * exit cleanly because the kobject reference wasn't made.
246          */
247         if (!tty->driver_data)
248                 return;
249
250         hp = tty->driver_data;
251         spin_lock_irqsave(&hp->lock, flags);
252
253         kobjp = &hp->kobj;
254         if (--hp->count == 0) {
255                 if (hp->irq_requested)
256                         irq = hp->irq;
257                 hp->irq_requested = 0;
258
259                 /* We are done with the tty pointer now. */
260                 hp->tty = NULL;
261                 spin_unlock_irqrestore(&hp->lock, flags);
262
263                 /*
264                  * Chain calls chars_in_buffer() and returns immediately if
265                  * there is no buffered data otherwise sleeps on a wait queue
266                  * waking periodically to check chars_in_buffer().
267                  */
268                 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
269
270                 if (irq != NO_IRQ)
271                         free_irq(irq, hp);
272
273         } else {
274                 if (hp->count < 0)
275                         printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
276                                 hp->vtermno, hp->count);
277                 spin_unlock_irqrestore(&hp->lock, flags);
278         }
279
280         kobject_put(kobjp);
281 }
282
283 static void hvc_hangup(struct tty_struct *tty)
284 {
285         struct hvc_struct *hp = tty->driver_data;
286         unsigned long flags;
287         int irq = NO_IRQ;
288         int temp_open_count;
289         struct kobject *kobjp;
290
291         if (!hp)
292                 return;
293
294         spin_lock_irqsave(&hp->lock, flags);
295
296         /*
297          * The N_TTY line discipline has problems such that in a close vs
298          * open->hangup case this can be called after the final close so prevent
299          * that from happening for now.
300          */
301         if (hp->count <= 0) {
302                 spin_unlock_irqrestore(&hp->lock, flags);
303                 return;
304         }
305
306         kobjp = &hp->kobj;
307         temp_open_count = hp->count;
308         hp->count = 0;
309         hp->n_outbuf = 0;
310         hp->tty = NULL;
311         if (hp->irq_requested)
312                 /* Saved for use outside of spin_lock. */
313                 irq = hp->irq;
314         hp->irq_requested = 0;
315         spin_unlock_irqrestore(&hp->lock, flags);
316         if (irq != NO_IRQ)
317                 free_irq(irq, hp);
318         while(temp_open_count) {
319                 --temp_open_count;
320                 kobject_put(kobjp);
321         }
322 }
323
324 /*
325  * Push buffered characters whether they were just recently buffered or waiting
326  * on a blocked hypervisor.  Call this function with hp->lock held.
327  */
328 static void hvc_push(struct hvc_struct *hp)
329 {
330         int n;
331
332         n = hvc_put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
333         if (n <= 0) {
334                 if (n == 0)
335                         return;
336                 /* throw away output on error; this happens when
337                    there is no session connected to the vterm. */
338                 hp->n_outbuf = 0;
339         } else
340                 hp->n_outbuf -= n;
341         if (hp->n_outbuf > 0)
342                 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
343         else
344                 hp->do_wakeup = 1;
345 }
346
347 static inline int __hvc_write_kernel(struct hvc_struct *hp,
348                                    const unsigned char *buf, int count)
349 {
350         unsigned long flags;
351         int rsize, written = 0;
352
353         spin_lock_irqsave(&hp->lock, flags);
354
355         /* Push pending writes */
356         if (hp->n_outbuf > 0)
357                 hvc_push(hp);
358
359         while (count > 0 && (rsize = N_OUTBUF - hp->n_outbuf) > 0) {
360                 if (rsize > count)
361                         rsize = count;
362                 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
363                 count -= rsize;
364                 buf += rsize;
365                 hp->n_outbuf += rsize;
366                 written += rsize;
367                 hvc_push(hp);
368         }
369         spin_unlock_irqrestore(&hp->lock, flags);
370
371         return written;
372 }
373 static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
374 {
375         struct hvc_struct *hp = tty->driver_data;
376         int written;
377
378         /* This write was probably executed during a tty close. */
379         if (!hp)
380                 return -EPIPE;
381
382         if (hp->count <= 0)
383                 return -EIO;
384
385         written = __hvc_write_kernel(hp, buf, count);
386
387         /*
388          * Racy, but harmless, kick thread if there is still pending data.
389          * There really is nothing wrong with kicking the thread, even if there
390          * is no buffered data.
391          */
392         if (hp->n_outbuf)
393                 hvc_kick();
394
395         return written;
396 }
397
398 /*
399  * This is actually a contract between the driver and the tty layer outlining
400  * how much write room the driver can guarentee will be sent OR BUFFERED.  This
401  * driver MUST honor the return value.
402  */
403 static int hvc_write_room(struct tty_struct *tty)
404 {
405         struct hvc_struct *hp = tty->driver_data;
406
407         if (!hp)
408                 return -1;
409
410         return N_OUTBUF - hp->n_outbuf;
411 }
412
413 static int hvc_chars_in_buffer(struct tty_struct *tty)
414 {
415         struct hvc_struct *hp = tty->driver_data;
416
417         if (!hp)
418                 return -1;
419         return hp->n_outbuf;
420 }
421
422 #define HVC_POLL_READ   0x00000001
423 #define HVC_POLL_WRITE  0x00000002
424 #define HVC_POLL_QUICK  0x00000004
425
426 static int hvc_poll(struct hvc_struct *hp)
427 {
428         struct tty_struct *tty;
429         int i, n, poll_mask = 0;
430         char buf[N_INBUF] __ALIGNED__;
431         unsigned long flags;
432         int read_total = 0;
433
434         spin_lock_irqsave(&hp->lock, flags);
435
436         /* Push pending writes */
437         if (hp->n_outbuf > 0)
438                 hvc_push(hp);
439         /* Reschedule us if still some write pending */
440         if (hp->n_outbuf > 0)
441                 poll_mask |= HVC_POLL_WRITE;
442
443         /* No tty attached, just skip */
444         tty = hp->tty;
445         if (tty == NULL)
446                 goto bail;
447
448         /* Now check if we can get data (are we throttled ?) */
449         if (test_bit(TTY_THROTTLED, &tty->flags))
450                 goto throttled;
451
452         /* If we aren't interrupt driven and aren't throttled, we always
453          * request a reschedule
454          */
455         if (hp->irq == NO_IRQ)
456                 poll_mask |= HVC_POLL_READ;
457
458         /* Read data if any */
459         for (;;) {
460                 int count = N_INBUF;
461                 if (count > (TTY_FLIPBUF_SIZE - tty->flip.count))
462                         count = TTY_FLIPBUF_SIZE - tty->flip.count;
463
464                 /* If flip is full, just reschedule a later read */
465                 if (count == 0) {
466                         poll_mask |= HVC_POLL_READ;
467                         break;
468                 }
469
470                 n = hvc_get_chars(hp->vtermno, buf, count);
471                 if (n <= 0) {
472                         /* Hangup the tty when disconnected from host */
473                         if (n == -EPIPE) {
474                                 spin_unlock_irqrestore(&hp->lock, flags);
475                                 tty_hangup(tty);
476                                 spin_lock_irqsave(&hp->lock, flags);
477                         }
478                         break;
479                 }
480                 for (i = 0; i < n; ++i) {
481 #ifdef CONFIG_MAGIC_SYSRQ
482                         /* Handle the SysRq Hack */
483                         if (buf[i] == '\x0f') { /* ^O -- should support a sequence */
484                                 sysrq_pressed = 1;
485                                 continue;
486                         } else if (sysrq_pressed) {
487                                 handle_sysrq(buf[i], NULL, tty);
488                                 sysrq_pressed = 0;
489                                 continue;
490                         }
491 #endif /* CONFIG_MAGIC_SYSRQ */
492                         tty_insert_flip_char(tty, buf[i], 0);
493                 }
494
495                 if (tty->flip.count)
496                         tty_schedule_flip(tty);
497
498                 /*
499                  * Account for the total amount read in one loop, and if above
500                  * 64 bytes, we do a quick schedule loop to let the tty grok the
501                  * data and eventually throttle us.
502                  */
503                 read_total += n;
504                 if (read_total >= 64) {
505                         poll_mask |= HVC_POLL_QUICK;
506                         break;
507                 }
508         }
509  throttled:
510         /* Wakeup write queue if necessary */
511         if (hp->do_wakeup) {
512                 hp->do_wakeup = 0;
513                 tty_wakeup(tty);
514         }
515  bail:
516         spin_unlock_irqrestore(&hp->lock, flags);
517
518         return poll_mask;
519 }
520
521 #if defined(CONFIG_XMON) && defined(CONFIG_SMP)
522 extern cpumask_t cpus_in_xmon;
523 #else
524 static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
525 #endif
526
527 /*
528  * This kthread is either polling or interrupt driven.  This is determined by
529  * calling hvc_poll() who determines whether a console adapter support
530  * interrupts.
531  */
532 int khvcd(void *unused)
533 {
534         int poll_mask;
535         struct hvc_struct *hp;
536
537         __set_current_state(TASK_RUNNING);
538         do {
539                 poll_mask = 0;
540                 hvc_kicked = 0;
541                 wmb();
542                 if (cpus_empty(cpus_in_xmon)) {
543                         spin_lock(&hvc_structs_lock);
544                         list_for_each_entry(hp, &hvc_structs, next) {
545                                 /*hp = list_entry(node, struct hvc_struct, * next); */
546                                 poll_mask |= hvc_poll(hp);
547                         }
548                         spin_unlock(&hvc_structs_lock);
549                 } else
550                         poll_mask |= HVC_POLL_READ;
551                 if (hvc_kicked)
552                         continue;
553                 if (poll_mask & HVC_POLL_QUICK) {
554                         yield();
555                         continue;
556                 }
557                 set_current_state(TASK_INTERRUPTIBLE);
558                 if (!hvc_kicked) {
559                         if (poll_mask == 0)
560                                 schedule();
561                         else
562                                 msleep_interruptible(TIMEOUT);
563                 }
564                 __set_current_state(TASK_RUNNING);
565         } while (!kthread_should_stop());
566
567         return 0;
568 }
569
570 static struct tty_operations hvc_ops = {
571         .open = hvc_open,
572         .close = hvc_close,
573         .write = hvc_write,
574         .hangup = hvc_hangup,
575         .unthrottle = hvc_unthrottle,
576         .write_room = hvc_write_room,
577         .chars_in_buffer = hvc_chars_in_buffer,
578 };
579
580 char hvc_driver_name[] = "hvc_console";
581
582 static struct vio_device_id hvc_driver_table[] __devinitdata= {
583         {"serial", "hvterm1"},
584         { NULL, }
585 };
586 MODULE_DEVICE_TABLE(vio, hvc_driver_table);
587
588 /* callback when the kboject ref count reaches zero. */
589 static void destroy_hvc_struct(struct kobject *kobj)
590 {
591         struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
592         unsigned long flags;
593
594         spin_lock(&hvc_structs_lock);
595
596         spin_lock_irqsave(&hp->lock, flags);
597         list_del(&(hp->next));
598         spin_unlock_irqrestore(&hp->lock, flags);
599
600         spin_unlock(&hvc_structs_lock);
601
602         kfree(hp);
603 }
604
605 static struct kobj_type hvc_kobj_type = {
606         .release = destroy_hvc_struct,
607 };
608
609 static int __devinit hvc_probe(
610                 struct vio_dev *dev,
611                 const struct vio_device_id *id)
612 {
613         struct hvc_struct *hp;
614
615         /* probed with invalid parameters. */
616         if (!dev || !id)
617                 return -EPERM;
618
619         hp = kmalloc(sizeof(*hp), GFP_KERNEL);
620         if (!hp)
621                 return -ENOMEM;
622
623         memset(hp, 0x00, sizeof(*hp));
624         hp->vtermno = dev->unit_address;
625         hp->vdev = dev;
626         hp->vdev->dev.driver_data = hp;
627         hp->irq = dev->irq;
628
629         kobject_init(&hp->kobj);
630         hp->kobj.ktype = &hvc_kobj_type;
631
632         spin_lock_init(&hp->lock);
633         spin_lock(&hvc_structs_lock);
634         hp->index = ++hvc_count;
635         list_add_tail(&(hp->next), &hvc_structs);
636         spin_unlock(&hvc_structs_lock);
637
638         return 0;
639 }
640
641 static int __devexit hvc_remove(struct vio_dev *dev)
642 {
643         struct hvc_struct *hp = dev->dev.driver_data;
644         unsigned long flags;
645         struct kobject *kobjp;
646         struct tty_struct *tty;
647
648         spin_lock_irqsave(&hp->lock, flags);
649         tty = hp->tty;
650         kobjp = &hp->kobj;
651
652         if (hp->index < MAX_NR_HVC_CONSOLES)
653                 vtermnos[hp->index] = -1;
654
655         /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
656
657         spin_unlock_irqrestore(&hp->lock, flags);
658
659         /*
660          * We 'put' the instance that was grabbed when the kobject instance
661          * was intialized using kobject_init().  Let the last holder of this
662          * kobject cause it to be removed, which will probably be the tty_hangup
663          * below.
664          */
665         kobject_put(kobjp);
666
667         /*
668          * This function call will auto chain call hvc_hangup.  The tty should
669          * always be valid at this time unless a simultaneous tty close already
670          * cleaned up the hvc_struct.
671          */
672         if (tty)
673                 tty_hangup(tty);
674         return 0;
675 }
676
677 static struct vio_driver hvc_vio_driver = {
678         .name           = hvc_driver_name,
679         .id_table       = hvc_driver_table,
680         .probe          = hvc_probe,
681         .remove         = hvc_remove,
682 };
683
684 /* Driver initialization.  Follow console initialization.  This is where the TTY
685  * interfaces start to become available. */
686 int __init hvc_init(void)
687 {
688         int rc;
689
690         /* We need more than num_vterms adapters due to hotplug additions. */
691         hvc_driver = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
692         /* hvc_driver = alloc_tty_driver(num_vterms); */
693         if (!hvc_driver)
694                 return -ENOMEM;
695
696         hvc_driver->owner = THIS_MODULE;
697         hvc_driver->devfs_name = "hvc/";
698         hvc_driver->driver_name = "hvc";
699         hvc_driver->name = "hvc";
700         hvc_driver->major = HVC_MAJOR;
701         hvc_driver->minor_start = HVC_MINOR;
702         hvc_driver->type = TTY_DRIVER_TYPE_SYSTEM;
703         hvc_driver->init_termios = tty_std_termios;
704         hvc_driver->flags = TTY_DRIVER_REAL_RAW;
705         tty_set_operations(hvc_driver, &hvc_ops);
706
707         if (tty_register_driver(hvc_driver))
708                 panic("Couldn't register hvc console driver\n");
709
710         /* Always start the kthread because there can be hotplug vty adapters
711          * added later. */
712         hvc_task = kthread_run(khvcd, NULL, "khvcd");
713         if (IS_ERR(hvc_task)) {
714                 panic("Couldn't create kthread for console.\n");
715                 put_tty_driver(hvc_driver);
716                 return -EIO;
717         }
718
719         /* Register as a vio device to receive callbacks */
720         rc = vio_register_driver(&hvc_vio_driver);
721
722         return rc;
723 }
724
725 /* This isn't particularily necessary due to this being a console driver but it
726  * is nice to be thorough */
727 static void __exit hvc_exit(void)
728 {
729         kthread_stop(hvc_task);
730
731         vio_unregister_driver(&hvc_vio_driver);
732         tty_unregister_driver(hvc_driver);
733         /* return tty_struct instances allocated in hvc_init(). */
734         put_tty_driver(hvc_driver);
735 }
736
737 /*
738  * Console APIs, NOT TTY.  These APIs are available immediately when
739  * hvc_console_setup() finds adapters.
740  */
741
742 /*
743  * hvc_instantiate() is an early console discovery method which locates consoles
744  * prior to the vio subsystem discovering them.  Hotplugged vty adapters do NOT
745  * get an hvc_instantiate() callback since the appear after early console init.
746  */
747 int hvc_instantiate(uint32_t vtermno, int index)
748 {
749         if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
750                 return -1;
751
752         if (vtermnos[index] != -1)
753                 return -1;
754
755         vtermnos[index] = vtermno;
756         return 0;
757 }
758
759 void hvc_console_print(struct console *co, const char *b, unsigned count)
760 {
761         char c[16] __ALIGNED__;
762         unsigned i = 0, n = 0;
763         int r, donecr = 0;
764
765         /* Console access attempt outside of acceptable console range. */
766         if (co->index >= MAX_NR_HVC_CONSOLES)
767                 return;
768
769         /* This console adapter was removed so it is not useable. */
770         if (vtermnos[co->index] < 0)
771                 return;
772
773         while (count > 0 || i > 0) {
774                 if (count > 0 && i < sizeof(c)) {
775                         if (b[n] == '\n' && !donecr) {
776                                 c[i++] = '\r';
777                                 donecr = 1;
778                         } else {
779                                 c[i++] = b[n++];
780                                 donecr = 0;
781                                 --count;
782                         }
783                 } else {
784                         r = hvc_put_chars(vtermnos[co->index], c, i);
785                         if (r < 0) {
786                                 /* throw away chars on error */
787                                 i = 0;
788                         } else if (r > 0) {
789                                 i -= r;
790                                 if (i > 0)
791                                         memmove(c, c+r, i);
792                         }
793                 }
794         }
795 }
796
797 static struct tty_driver *hvc_console_device(struct console *c, int *index)
798 {
799         *index = c->index;
800         return hvc_driver;
801 }
802
803 static int __init hvc_console_setup(struct console *co, char *options)
804 {
805         return 0;
806 }
807
808 struct console hvc_con_driver = {
809         .name           = "hvc",
810         .write          = hvc_console_print,
811         .device         = hvc_console_device,
812         .setup          = hvc_console_setup,
813         .flags          = CON_PRINTBUFFER,
814         .index          = -1,
815 };
816
817 /* Early console initialization.  Preceeds driver initialization. */
818 static int __init hvc_console_init(void)
819 {
820         int i;
821
822         for (i=0; i<MAX_NR_HVC_CONSOLES; i++)
823                 vtermnos[i] = -1;
824         num_vterms = hvc_find_vtys();
825         register_console(&hvc_con_driver);
826         return 0;
827 }
828 console_initcall(hvc_console_init);
829
830 module_init(hvc_init);
831 module_exit(hvc_exit);