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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/kthread.h>
31#include <linux/list.h>
32#include <linux/module.h>
33#include <linux/major.h>
34#include <linux/sysrq.h>
35#include <linux/tty.h>
36#include <linux/tty_flip.h>
37#include <linux/sched.h>
38#include <linux/spinlock.h>
39#include <linux/delay.h>
40#include <linux/freezer.h>
41#include <linux/slab.h>
42#include <linux/serial_core.h>
43
44#include <asm/uaccess.h>
45
46#include "hvc_console.h"
47
48#define HVC_MAJOR 229
49#define HVC_MINOR 0
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 * 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
64
65#define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
66
67static struct tty_driver *hvc_driver;
68static struct task_struct *hvc_task;
69
70/* Picks up late kicks after list walk but before schedule() */
71static int hvc_kicked;
72
73static int hvc_init(void);
74
75#ifdef CONFIG_MAGIC_SYSRQ
76static int sysrq_pressed;
77#endif
78
79/* dynamic list of hvc_struct instances */
80static LIST_HEAD(hvc_structs);
81
82/*
83 * Protect the list of hvc_struct instances from inserts and removals during
84 * list traversal.
85 */
86static DEFINE_SPINLOCK(hvc_structs_lock);
87
88/*
89 * This value is used to assign a tty->index value to a hvc_struct based
90 * upon order of exposure via hvc_probe(), when we can not match it to
91 * a console candidate registered with hvc_instantiate().
92 */
93static int last_hvc = -1;
94
95/*
96 * Do not call this function with either the hvc_structs_lock or the hvc_struct
97 * lock held. If successful, this function increments the kref reference
98 * count against the target hvc_struct so it should be released when finished.
99 */
100static struct hvc_struct *hvc_get_by_index(int index)
101{
102 struct hvc_struct *hp;
103 unsigned long flags;
104
105 spin_lock(&hvc_structs_lock);
106
107 list_for_each_entry(hp, &hvc_structs, next) {
108 spin_lock_irqsave(&hp->lock, flags);
109 if (hp->index == index) {
110 kref_get(&hp->kref);
111 spin_unlock_irqrestore(&hp->lock, flags);
112 spin_unlock(&hvc_structs_lock);
113 return hp;
114 }
115 spin_unlock_irqrestore(&hp->lock, flags);
116 }
117 hp = NULL;
118
119 spin_unlock(&hvc_structs_lock);
120 return hp;
121}
122
123
124/*
125 * Initial console vtermnos for console API usage prior to full console
126 * initialization. Any vty adapter outside this range will not have usable
127 * console interfaces but can still be used as a tty device. This has to be
128 * static because kmalloc will not work during early console init.
129 */
130static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
131static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
132 {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
133
134/*
135 * Console APIs, NOT TTY. These APIs are available immediately when
136 * hvc_console_setup() finds adapters.
137 */
138
139static void hvc_console_print(struct console *co, const char *b,
140 unsigned count)
141{
142 char c[N_OUTBUF] __ALIGNED__;
143 unsigned i = 0, n = 0;
144 int r, donecr = 0, index = co->index;
145
146 /* Console access attempt outside of acceptable console range. */
147 if (index >= MAX_NR_HVC_CONSOLES)
148 return;
149
150 /* This console adapter was removed so it is not usable. */
151 if (vtermnos[index] == -1)
152 return;
153
154 while (count > 0 || i > 0) {
155 if (count > 0 && i < sizeof(c)) {
156 if (b[n] == '\n' && !donecr) {
157 c[i++] = '\r';
158 donecr = 1;
159 } else {
160 c[i++] = b[n++];
161 donecr = 0;
162 --count;
163 }
164 } else {
165 r = cons_ops[index]->put_chars(vtermnos[index], c, i);
166 if (r <= 0) {
167 /* throw away characters on error
168 * but spin in case of -EAGAIN */
169 if (r != -EAGAIN)
170 i = 0;
171 } else if (r > 0) {
172 i -= r;
173 if (i > 0)
174 memmove(c, c+r, i);
175 }
176 }
177 }
178}
179
180static struct tty_driver *hvc_console_device(struct console *c, int *index)
181{
182 if (vtermnos[c->index] == -1)
183 return NULL;
184
185 *index = c->index;
186 return hvc_driver;
187}
188
189static int __init hvc_console_setup(struct console *co, char *options)
190{
191 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
192 return -ENODEV;
193
194 if (vtermnos[co->index] == -1)
195 return -ENODEV;
196
197 return 0;
198}
199
200static struct console hvc_console = {
201 .name = "hvc",
202 .write = hvc_console_print,
203 .device = hvc_console_device,
204 .setup = hvc_console_setup,
205 .flags = CON_PRINTBUFFER,
206 .index = -1,
207};
208
209/*
210 * Early console initialization. Precedes driver initialization.
211 *
212 * (1) we are first, and the user specified another driver
213 * -- index will remain -1
214 * (2) we are first and the user specified no driver
215 * -- index will be set to 0, then we will fail setup.
216 * (3) we are first and the user specified our driver
217 * -- index will be set to user specified driver, and we will fail
218 * (4) we are after driver, and this initcall will register us
219 * -- if the user didn't specify a driver then the console will match
220 *
221 * Note that for cases 2 and 3, we will match later when the io driver
222 * calls hvc_instantiate() and call register again.
223 */
224static int __init hvc_console_init(void)
225{
226 register_console(&hvc_console);
227 return 0;
228}
229console_initcall(hvc_console_init);
230
231/* callback when the kboject ref count reaches zero. */
232static void destroy_hvc_struct(struct kref *kref)
233{
234 struct hvc_struct *hp = container_of(kref, struct hvc_struct, kref);
235 unsigned long flags;
236
237 spin_lock(&hvc_structs_lock);
238
239 spin_lock_irqsave(&hp->lock, flags);
240 list_del(&(hp->next));
241 spin_unlock_irqrestore(&hp->lock, flags);
242
243 spin_unlock(&hvc_structs_lock);
244
245 kfree(hp);
246}
247
248/*
249 * hvc_instantiate() is an early console discovery method which locates
250 * consoles * prior to the vio subsystem discovering them. Hotplugged
251 * vty adapters do NOT get an hvc_instantiate() callback since they
252 * appear after early console init.
253 */
254int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
255{
256 struct hvc_struct *hp;
257
258 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
259 return -1;
260
261 if (vtermnos[index] != -1)
262 return -1;
263
264 /* make sure no no tty has been registered in this index */
265 hp = hvc_get_by_index(index);
266 if (hp) {
267 kref_put(&hp->kref, destroy_hvc_struct);
268 return -1;
269 }
270
271 vtermnos[index] = vtermno;
272 cons_ops[index] = ops;
273
274 /* reserve all indices up to and including this index */
275 if (last_hvc < index)
276 last_hvc = index;
277
278 /* if this index is what the user requested, then register
279 * now (setup won't fail at this point). It's ok to just
280 * call register again if previously .setup failed.
281 */
282 if (index == hvc_console.index)
283 register_console(&hvc_console);
284
285 return 0;
286}
287EXPORT_SYMBOL_GPL(hvc_instantiate);
288
289/* Wake the sleeping khvcd */
290void hvc_kick(void)
291{
292 hvc_kicked = 1;
293 wake_up_process(hvc_task);
294}
295EXPORT_SYMBOL_GPL(hvc_kick);
296
297static void hvc_unthrottle(struct tty_struct *tty)
298{
299 hvc_kick();
300}
301
302/*
303 * The TTY interface won't be used until after the vio layer has exposed the vty
304 * adapter to the kernel.
305 */
306static int hvc_open(struct tty_struct *tty, struct file * filp)
307{
308 struct hvc_struct *hp;
309 unsigned long flags;
310 int rc = 0;
311
312 /* Auto increments kref reference if found. */
313 if (!(hp = hvc_get_by_index(tty->index)))
314 return -ENODEV;
315
316 spin_lock_irqsave(&hp->lock, flags);
317 /* Check and then increment for fast path open. */
318 if (hp->count++ > 0) {
319 tty_kref_get(tty);
320 spin_unlock_irqrestore(&hp->lock, flags);
321 hvc_kick();
322 return 0;
323 } /* else count == 0 */
324
325 tty->driver_data = hp;
326
327 hp->tty = tty_kref_get(tty);
328
329 spin_unlock_irqrestore(&hp->lock, flags);
330
331 if (hp->ops->notifier_add)
332 rc = hp->ops->notifier_add(hp, hp->data);
333
334 /*
335 * If the notifier fails we return an error. The tty layer
336 * will call hvc_close() after a failed open but we don't want to clean
337 * up there so we'll clean up here and clear out the previously set
338 * tty fields and return the kref reference.
339 */
340 if (rc) {
341 spin_lock_irqsave(&hp->lock, flags);
342 hp->tty = NULL;
343 spin_unlock_irqrestore(&hp->lock, flags);
344 tty_kref_put(tty);
345 tty->driver_data = NULL;
346 kref_put(&hp->kref, destroy_hvc_struct);
347 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
348 }
349 /* Force wakeup of the polling thread */
350 hvc_kick();
351
352 return rc;
353}
354
355static void hvc_close(struct tty_struct *tty, struct file * filp)
356{
357 struct hvc_struct *hp;
358 unsigned long flags;
359
360 if (tty_hung_up_p(filp))
361 return;
362
363 /*
364 * No driver_data means that this close was issued after a failed
365 * hvc_open by the tty layer's release_dev() function and we can just
366 * exit cleanly because the kref reference wasn't made.
367 */
368 if (!tty->driver_data)
369 return;
370
371 hp = tty->driver_data;
372
373 spin_lock_irqsave(&hp->lock, flags);
374
375 if (--hp->count == 0) {
376 /* We are done with the tty pointer now. */
377 hp->tty = NULL;
378 spin_unlock_irqrestore(&hp->lock, flags);
379
380 if (hp->ops->notifier_del)
381 hp->ops->notifier_del(hp, hp->data);
382
383 /* cancel pending tty resize work */
384 cancel_work_sync(&hp->tty_resize);
385
386 /*
387 * Chain calls chars_in_buffer() and returns immediately if
388 * there is no buffered data otherwise sleeps on a wait queue
389 * waking periodically to check chars_in_buffer().
390 */
391 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
392 } else {
393 if (hp->count < 0)
394 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
395 hp->vtermno, hp->count);
396 spin_unlock_irqrestore(&hp->lock, flags);
397 }
398
399 tty_kref_put(tty);
400 kref_put(&hp->kref, destroy_hvc_struct);
401}
402
403static void hvc_hangup(struct tty_struct *tty)
404{
405 struct hvc_struct *hp = tty->driver_data;
406 unsigned long flags;
407 int temp_open_count;
408
409 if (!hp)
410 return;
411
412 /* cancel pending tty resize work */
413 cancel_work_sync(&hp->tty_resize);
414
415 spin_lock_irqsave(&hp->lock, flags);
416
417 /*
418 * The N_TTY line discipline has problems such that in a close vs
419 * open->hangup case this can be called after the final close so prevent
420 * that from happening for now.
421 */
422 if (hp->count <= 0) {
423 spin_unlock_irqrestore(&hp->lock, flags);
424 return;
425 }
426
427 temp_open_count = hp->count;
428 hp->count = 0;
429 hp->n_outbuf = 0;
430 hp->tty = NULL;
431
432 spin_unlock_irqrestore(&hp->lock, flags);
433
434 if (hp->ops->notifier_hangup)
435 hp->ops->notifier_hangup(hp, hp->data);
436
437 while(temp_open_count) {
438 --temp_open_count;
439 tty_kref_put(tty);
440 kref_put(&hp->kref, destroy_hvc_struct);
441 }
442}
443
444/*
445 * Push buffered characters whether they were just recently buffered or waiting
446 * on a blocked hypervisor. Call this function with hp->lock held.
447 */
448static int hvc_push(struct hvc_struct *hp)
449{
450 int n;
451
452 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
453 if (n <= 0) {
454 if (n == 0 || n == -EAGAIN) {
455 hp->do_wakeup = 1;
456 return 0;
457 }
458 /* throw away output on error; this happens when
459 there is no session connected to the vterm. */
460 hp->n_outbuf = 0;
461 } else
462 hp->n_outbuf -= n;
463 if (hp->n_outbuf > 0)
464 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
465 else
466 hp->do_wakeup = 1;
467
468 return n;
469}
470
471static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
472{
473 struct hvc_struct *hp = tty->driver_data;
474 unsigned long flags;
475 int rsize, written = 0;
476
477 /* This write was probably executed during a tty close. */
478 if (!hp)
479 return -EPIPE;
480
481 if (hp->count <= 0)
482 return -EIO;
483
484 spin_lock_irqsave(&hp->lock, flags);
485
486 /* Push pending writes */
487 if (hp->n_outbuf > 0)
488 hvc_push(hp);
489
490 while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
491 if (rsize > count)
492 rsize = count;
493 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
494 count -= rsize;
495 buf += rsize;
496 hp->n_outbuf += rsize;
497 written += rsize;
498 hvc_push(hp);
499 }
500 spin_unlock_irqrestore(&hp->lock, flags);
501
502 /*
503 * Racy, but harmless, kick thread if there is still pending data.
504 */
505 if (hp->n_outbuf)
506 hvc_kick();
507
508 return written;
509}
510
511/**
512 * hvc_set_winsz() - Resize the hvc tty terminal window.
513 * @work: work structure.
514 *
515 * The routine shall not be called within an atomic context because it
516 * might sleep.
517 *
518 * Locking: hp->lock
519 */
520static void hvc_set_winsz(struct work_struct *work)
521{
522 struct hvc_struct *hp;
523 unsigned long hvc_flags;
524 struct tty_struct *tty;
525 struct winsize ws;
526
527 hp = container_of(work, struct hvc_struct, tty_resize);
528
529 spin_lock_irqsave(&hp->lock, hvc_flags);
530 if (!hp->tty) {
531 spin_unlock_irqrestore(&hp->lock, hvc_flags);
532 return;
533 }
534 ws = hp->ws;
535 tty = tty_kref_get(hp->tty);
536 spin_unlock_irqrestore(&hp->lock, hvc_flags);
537
538 tty_do_resize(tty, &ws);
539 tty_kref_put(tty);
540}
541
542/*
543 * This is actually a contract between the driver and the tty layer outlining
544 * how much write room the driver can guarantee will be sent OR BUFFERED. This
545 * driver MUST honor the return value.
546 */
547static int hvc_write_room(struct tty_struct *tty)
548{
549 struct hvc_struct *hp = tty->driver_data;
550
551 if (!hp)
552 return -1;
553
554 return hp->outbuf_size - hp->n_outbuf;
555}
556
557static int hvc_chars_in_buffer(struct tty_struct *tty)
558{
559 struct hvc_struct *hp = tty->driver_data;
560
561 if (!hp)
562 return 0;
563 return hp->n_outbuf;
564}
565
566/*
567 * timeout will vary between the MIN and MAX values defined here. By default
568 * and during console activity we will use a default MIN_TIMEOUT of 10. When
569 * the console is idle, we increase the timeout value on each pass through
570 * msleep until we reach the max. This may be noticeable as a brief (average
571 * one second) delay on the console before the console responds to input when
572 * there has been no input for some time.
573 */
574#define MIN_TIMEOUT (10)
575#define MAX_TIMEOUT (2000)
576static u32 timeout = MIN_TIMEOUT;
577
578#define HVC_POLL_READ 0x00000001
579#define HVC_POLL_WRITE 0x00000002
580
581int hvc_poll(struct hvc_struct *hp)
582{
583 struct tty_struct *tty;
584 int i, n, poll_mask = 0;
585 char buf[N_INBUF] __ALIGNED__;
586 unsigned long flags;
587 int read_total = 0;
588 int written_total = 0;
589
590 spin_lock_irqsave(&hp->lock, flags);
591
592 /* Push pending writes */
593 if (hp->n_outbuf > 0)
594 written_total = hvc_push(hp);
595
596 /* Reschedule us if still some write pending */
597 if (hp->n_outbuf > 0) {
598 poll_mask |= HVC_POLL_WRITE;
599 /* If hvc_push() was not able to write, sleep a few msecs */
600 timeout = (written_total) ? 0 : MIN_TIMEOUT;
601 }
602
603 /* No tty attached, just skip */
604 tty = tty_kref_get(hp->tty);
605 if (tty == NULL)
606 goto bail;
607
608 /* Now check if we can get data (are we throttled ?) */
609 if (test_bit(TTY_THROTTLED, &tty->flags))
610 goto throttled;
611
612 /* If we aren't notifier driven and aren't throttled, we always
613 * request a reschedule
614 */
615 if (!hp->irq_requested)
616 poll_mask |= HVC_POLL_READ;
617
618 /* Read data if any */
619 for (;;) {
620 int count = tty_buffer_request_room(tty, N_INBUF);
621
622 /* If flip is full, just reschedule a later read */
623 if (count == 0) {
624 poll_mask |= HVC_POLL_READ;
625 break;
626 }
627
628 n = hp->ops->get_chars(hp->vtermno, buf, count);
629 if (n <= 0) {
630 /* Hangup the tty when disconnected from host */
631 if (n == -EPIPE) {
632 spin_unlock_irqrestore(&hp->lock, flags);
633 tty_hangup(tty);
634 spin_lock_irqsave(&hp->lock, flags);
635 } else if ( n == -EAGAIN ) {
636 /*
637 * Some back-ends can only ensure a certain min
638 * num of bytes read, which may be > 'count'.
639 * Let the tty clear the flip buff to make room.
640 */
641 poll_mask |= HVC_POLL_READ;
642 }
643 break;
644 }
645 for (i = 0; i < n; ++i) {
646#ifdef CONFIG_MAGIC_SYSRQ
647 if (hp->index == hvc_console.index) {
648 /* Handle the SysRq Hack */
649 /* XXX should support a sequence */
650 if (buf[i] == '\x0f') { /* ^O */
651 /* if ^O is pressed again, reset
652 * sysrq_pressed and flip ^O char */
653 sysrq_pressed = !sysrq_pressed;
654 if (sysrq_pressed)
655 continue;
656 } else if (sysrq_pressed) {
657 handle_sysrq(buf[i]);
658 sysrq_pressed = 0;
659 continue;
660 }
661 }
662#endif /* CONFIG_MAGIC_SYSRQ */
663 tty_insert_flip_char(tty, buf[i], 0);
664 }
665
666 read_total += n;
667 }
668 throttled:
669 /* Wakeup write queue if necessary */
670 if (hp->do_wakeup) {
671 hp->do_wakeup = 0;
672 tty_wakeup(tty);
673 }
674 bail:
675 spin_unlock_irqrestore(&hp->lock, flags);
676
677 if (read_total) {
678 /* Activity is occurring, so reset the polling backoff value to
679 a minimum for performance. */
680 timeout = MIN_TIMEOUT;
681
682 tty_flip_buffer_push(tty);
683 }
684 if (tty)
685 tty_kref_put(tty);
686
687 return poll_mask;
688}
689EXPORT_SYMBOL_GPL(hvc_poll);
690
691/**
692 * __hvc_resize() - Update terminal window size information.
693 * @hp: HVC console pointer
694 * @ws: Terminal window size structure
695 *
696 * Stores the specified window size information in the hvc structure of @hp.
697 * The function schedule the tty resize update.
698 *
699 * Locking: Locking free; the function MUST be called holding hp->lock
700 */
701void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
702{
703 hp->ws = ws;
704 schedule_work(&hp->tty_resize);
705}
706EXPORT_SYMBOL_GPL(__hvc_resize);
707
708/*
709 * This kthread is either polling or interrupt driven. This is determined by
710 * calling hvc_poll() who determines whether a console adapter support
711 * interrupts.
712 */
713static int khvcd(void *unused)
714{
715 int poll_mask;
716 struct hvc_struct *hp;
717
718 set_freezable();
719 do {
720 poll_mask = 0;
721 hvc_kicked = 0;
722 try_to_freeze();
723 wmb();
724 if (!cpus_are_in_xmon()) {
725 spin_lock(&hvc_structs_lock);
726 list_for_each_entry(hp, &hvc_structs, next) {
727 poll_mask |= hvc_poll(hp);
728 }
729 spin_unlock(&hvc_structs_lock);
730 } else
731 poll_mask |= HVC_POLL_READ;
732 if (hvc_kicked)
733 continue;
734 set_current_state(TASK_INTERRUPTIBLE);
735 if (!hvc_kicked) {
736 if (poll_mask == 0)
737 schedule();
738 else {
739 if (timeout < MAX_TIMEOUT)
740 timeout += (timeout >> 6) + 1;
741
742 msleep_interruptible(timeout);
743 }
744 }
745 __set_current_state(TASK_RUNNING);
746 } while (!kthread_should_stop());
747
748 return 0;
749}
750
751static int hvc_tiocmget(struct tty_struct *tty)
752{
753 struct hvc_struct *hp = tty->driver_data;
754
755 if (!hp || !hp->ops->tiocmget)
756 return -EINVAL;
757 return hp->ops->tiocmget(hp);
758}
759
760static int hvc_tiocmset(struct tty_struct *tty,
761 unsigned int set, unsigned int clear)
762{
763 struct hvc_struct *hp = tty->driver_data;
764
765 if (!hp || !hp->ops->tiocmset)
766 return -EINVAL;
767 return hp->ops->tiocmset(hp, set, clear);
768}
769
770#ifdef CONFIG_CONSOLE_POLL
771int hvc_poll_init(struct tty_driver *driver, int line, char *options)
772{
773 return 0;
774}
775
776static int hvc_poll_get_char(struct tty_driver *driver, int line)
777{
778 struct tty_struct *tty = driver->ttys[0];
779 struct hvc_struct *hp = tty->driver_data;
780 int n;
781 char ch;
782
783 n = hp->ops->get_chars(hp->vtermno, &ch, 1);
784
785 if (n == 0)
786 return NO_POLL_CHAR;
787
788 return ch;
789}
790
791static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
792{
793 struct tty_struct *tty = driver->ttys[0];
794 struct hvc_struct *hp = tty->driver_data;
795 int n;
796
797 do {
798 n = hp->ops->put_chars(hp->vtermno, &ch, 1);
799 } while (n <= 0);
800}
801#endif
802
803static const struct tty_operations hvc_ops = {
804 .open = hvc_open,
805 .close = hvc_close,
806 .write = hvc_write,
807 .hangup = hvc_hangup,
808 .unthrottle = hvc_unthrottle,
809 .write_room = hvc_write_room,
810 .chars_in_buffer = hvc_chars_in_buffer,
811 .tiocmget = hvc_tiocmget,
812 .tiocmset = hvc_tiocmset,
813#ifdef CONFIG_CONSOLE_POLL
814 .poll_init = hvc_poll_init,
815 .poll_get_char = hvc_poll_get_char,
816 .poll_put_char = hvc_poll_put_char,
817#endif
818};
819
820struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
821 const struct hv_ops *ops,
822 int outbuf_size)
823{
824 struct hvc_struct *hp;
825 int i;
826
827 /* We wait until a driver actually comes along */
828 if (!hvc_driver) {
829 int err = hvc_init();
830 if (err)
831 return ERR_PTR(err);
832 }
833
834 hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
835 GFP_KERNEL);
836 if (!hp)
837 return ERR_PTR(-ENOMEM);
838
839 hp->vtermno = vtermno;
840 hp->data = data;
841 hp->ops = ops;
842 hp->outbuf_size = outbuf_size;
843 hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
844
845 kref_init(&hp->kref);
846
847 INIT_WORK(&hp->tty_resize, hvc_set_winsz);
848 spin_lock_init(&hp->lock);
849 spin_lock(&hvc_structs_lock);
850
851 /*
852 * find index to use:
853 * see if this vterm id matches one registered for console.
854 */
855 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
856 if (vtermnos[i] == hp->vtermno &&
857 cons_ops[i] == hp->ops)
858 break;
859
860 /* no matching slot, just use a counter */
861 if (i >= MAX_NR_HVC_CONSOLES)
862 i = ++last_hvc;
863
864 hp->index = i;
865
866 list_add_tail(&(hp->next), &hvc_structs);
867 spin_unlock(&hvc_structs_lock);
868
869 return hp;
870}
871EXPORT_SYMBOL_GPL(hvc_alloc);
872
873int hvc_remove(struct hvc_struct *hp)
874{
875 unsigned long flags;
876 struct tty_struct *tty;
877
878 spin_lock_irqsave(&hp->lock, flags);
879 tty = tty_kref_get(hp->tty);
880
881 if (hp->index < MAX_NR_HVC_CONSOLES)
882 vtermnos[hp->index] = -1;
883
884 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
885
886 spin_unlock_irqrestore(&hp->lock, flags);
887
888 /*
889 * We 'put' the instance that was grabbed when the kref instance
890 * was initialized using kref_init(). Let the last holder of this
891 * kref cause it to be removed, which will probably be the tty_vhangup
892 * below.
893 */
894 kref_put(&hp->kref, destroy_hvc_struct);
895
896 /*
897 * This function call will auto chain call hvc_hangup.
898 */
899 if (tty) {
900 tty_vhangup(tty);
901 tty_kref_put(tty);
902 }
903 return 0;
904}
905EXPORT_SYMBOL_GPL(hvc_remove);
906
907/* Driver initialization: called as soon as someone uses hvc_alloc(). */
908static int hvc_init(void)
909{
910 struct tty_driver *drv;
911 int err;
912
913 /* We need more than hvc_count adapters due to hotplug additions. */
914 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
915 if (!drv) {
916 err = -ENOMEM;
917 goto out;
918 }
919
920 drv->owner = THIS_MODULE;
921 drv->driver_name = "hvc";
922 drv->name = "hvc";
923 drv->major = HVC_MAJOR;
924 drv->minor_start = HVC_MINOR;
925 drv->type = TTY_DRIVER_TYPE_SYSTEM;
926 drv->init_termios = tty_std_termios;
927 drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
928 tty_set_operations(drv, &hvc_ops);
929
930 /* Always start the kthread because there can be hotplug vty adapters
931 * added later. */
932 hvc_task = kthread_run(khvcd, NULL, "khvcd");
933 if (IS_ERR(hvc_task)) {
934 printk(KERN_ERR "Couldn't create kthread for console.\n");
935 err = PTR_ERR(hvc_task);
936 goto put_tty;
937 }
938
939 err = tty_register_driver(drv);
940 if (err) {
941 printk(KERN_ERR "Couldn't register hvc console driver\n");
942 goto stop_thread;
943 }
944
945 /*
946 * Make sure tty is fully registered before allowing it to be
947 * found by hvc_console_device.
948 */
949 smp_mb();
950 hvc_driver = drv;
951 return 0;
952
953stop_thread:
954 kthread_stop(hvc_task);
955 hvc_task = NULL;
956put_tty:
957 put_tty_driver(drv);
958out:
959 return err;
960}
961
962/* This isn't particularly necessary due to this being a console driver
963 * but it is nice to be thorough.
964 */
965static void __exit hvc_exit(void)
966{
967 if (hvc_driver) {
968 kthread_stop(hvc_task);
969
970 tty_unregister_driver(hvc_driver);
971 /* return tty_struct instances allocated in hvc_init(). */
972 put_tty_driver(hvc_driver);
973 unregister_console(&hvc_console);
974 }
975}
976module_exit(hvc_exit);
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/kthread.h>
31#include <linux/list.h>
32#include <linux/module.h>
33#include <linux/major.h>
34#include <linux/atomic.h>
35#include <linux/sysrq.h>
36#include <linux/tty.h>
37#include <linux/tty_flip.h>
38#include <linux/sched.h>
39#include <linux/spinlock.h>
40#include <linux/delay.h>
41#include <linux/freezer.h>
42#include <linux/slab.h>
43#include <linux/serial_core.h>
44
45#include <asm/uaccess.h>
46
47#include "hvc_console.h"
48
49#define HVC_MAJOR 229
50#define HVC_MINOR 0
51
52/*
53 * Wait this long per iteration while trying to push buffered data to the
54 * hypervisor before allowing the tty to complete a close operation.
55 */
56#define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
57
58/*
59 * These sizes are most efficient for vio, because they are the
60 * native transfer size. We could make them selectable in the
61 * future to better deal with backends that want other buffer sizes.
62 */
63#define N_OUTBUF 16
64#define N_INBUF 16
65
66#define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
67
68static struct tty_driver *hvc_driver;
69static struct task_struct *hvc_task;
70
71/* Picks up late kicks after list walk but before schedule() */
72static int hvc_kicked;
73
74/* hvc_init is triggered from hvc_alloc, i.e. only when actually used */
75static atomic_t hvc_needs_init __read_mostly = ATOMIC_INIT(-1);
76
77static int hvc_init(void);
78
79#ifdef CONFIG_MAGIC_SYSRQ
80static int sysrq_pressed;
81#endif
82
83/* dynamic list of hvc_struct instances */
84static LIST_HEAD(hvc_structs);
85
86/*
87 * Protect the list of hvc_struct instances from inserts and removals during
88 * list traversal.
89 */
90static DEFINE_SPINLOCK(hvc_structs_lock);
91
92/*
93 * This value is used to assign a tty->index value to a hvc_struct based
94 * upon order of exposure via hvc_probe(), when we can not match it to
95 * a console candidate registered with hvc_instantiate().
96 */
97static int last_hvc = -1;
98
99/*
100 * Do not call this function with either the hvc_structs_lock or the hvc_struct
101 * lock held. If successful, this function increments the kref reference
102 * count against the target hvc_struct so it should be released when finished.
103 */
104static struct hvc_struct *hvc_get_by_index(int index)
105{
106 struct hvc_struct *hp;
107 unsigned long flags;
108
109 spin_lock(&hvc_structs_lock);
110
111 list_for_each_entry(hp, &hvc_structs, next) {
112 spin_lock_irqsave(&hp->lock, flags);
113 if (hp->index == index) {
114 tty_port_get(&hp->port);
115 spin_unlock_irqrestore(&hp->lock, flags);
116 spin_unlock(&hvc_structs_lock);
117 return hp;
118 }
119 spin_unlock_irqrestore(&hp->lock, flags);
120 }
121 hp = NULL;
122
123 spin_unlock(&hvc_structs_lock);
124 return hp;
125}
126
127
128/*
129 * Initial console vtermnos for console API usage prior to full console
130 * initialization. Any vty adapter outside this range will not have usable
131 * console interfaces but can still be used as a tty device. This has to be
132 * static because kmalloc will not work during early console init.
133 */
134static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
135static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
136 {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
137
138/*
139 * Console APIs, NOT TTY. These APIs are available immediately when
140 * hvc_console_setup() finds adapters.
141 */
142
143static void hvc_console_print(struct console *co, const char *b,
144 unsigned count)
145{
146 char c[N_OUTBUF] __ALIGNED__;
147 unsigned i = 0, n = 0;
148 int r, donecr = 0, index = co->index;
149
150 /* Console access attempt outside of acceptable console range. */
151 if (index >= MAX_NR_HVC_CONSOLES)
152 return;
153
154 /* This console adapter was removed so it is not usable. */
155 if (vtermnos[index] == -1)
156 return;
157
158 while (count > 0 || i > 0) {
159 if (count > 0 && i < sizeof(c)) {
160 if (b[n] == '\n' && !donecr) {
161 c[i++] = '\r';
162 donecr = 1;
163 } else {
164 c[i++] = b[n++];
165 donecr = 0;
166 --count;
167 }
168 } else {
169 r = cons_ops[index]->put_chars(vtermnos[index], c, i);
170 if (r <= 0) {
171 /* throw away characters on error
172 * but spin in case of -EAGAIN */
173 if (r != -EAGAIN)
174 i = 0;
175 } else if (r > 0) {
176 i -= r;
177 if (i > 0)
178 memmove(c, c+r, i);
179 }
180 }
181 }
182}
183
184static struct tty_driver *hvc_console_device(struct console *c, int *index)
185{
186 if (vtermnos[c->index] == -1)
187 return NULL;
188
189 *index = c->index;
190 return hvc_driver;
191}
192
193static int hvc_console_setup(struct console *co, char *options)
194{
195 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
196 return -ENODEV;
197
198 if (vtermnos[co->index] == -1)
199 return -ENODEV;
200
201 return 0;
202}
203
204static struct console hvc_console = {
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/*
214 * Early console initialization. Precedes driver initialization.
215 *
216 * (1) we are first, and the user specified another driver
217 * -- index will remain -1
218 * (2) we are first and the user specified no driver
219 * -- index will be set to 0, then we will fail setup.
220 * (3) we are first and the user specified our driver
221 * -- index will be set to user specified driver, and we will fail
222 * (4) we are after driver, and this initcall will register us
223 * -- if the user didn't specify a driver then the console will match
224 *
225 * Note that for cases 2 and 3, we will match later when the io driver
226 * calls hvc_instantiate() and call register again.
227 */
228static int __init hvc_console_init(void)
229{
230 register_console(&hvc_console);
231 return 0;
232}
233console_initcall(hvc_console_init);
234
235/* callback when the kboject ref count reaches zero. */
236static void hvc_port_destruct(struct tty_port *port)
237{
238 struct hvc_struct *hp = container_of(port, struct hvc_struct, port);
239 unsigned long flags;
240
241 spin_lock(&hvc_structs_lock);
242
243 spin_lock_irqsave(&hp->lock, flags);
244 list_del(&(hp->next));
245 spin_unlock_irqrestore(&hp->lock, flags);
246
247 spin_unlock(&hvc_structs_lock);
248
249 kfree(hp);
250}
251
252static void hvc_check_console(int index)
253{
254 /* Already enabled, bail out */
255 if (hvc_console.flags & CON_ENABLED)
256 return;
257
258 /* If this index is what the user requested, then register
259 * now (setup won't fail at this point). It's ok to just
260 * call register again if previously .setup failed.
261 */
262 if (index == hvc_console.index)
263 register_console(&hvc_console);
264}
265
266/*
267 * hvc_instantiate() is an early console discovery method which locates
268 * consoles * prior to the vio subsystem discovering them. Hotplugged
269 * vty adapters do NOT get an hvc_instantiate() callback since they
270 * appear after early console init.
271 */
272int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
273{
274 struct hvc_struct *hp;
275
276 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
277 return -1;
278
279 if (vtermnos[index] != -1)
280 return -1;
281
282 /* make sure no no tty has been registered in this index */
283 hp = hvc_get_by_index(index);
284 if (hp) {
285 tty_port_put(&hp->port);
286 return -1;
287 }
288
289 vtermnos[index] = vtermno;
290 cons_ops[index] = ops;
291
292 /* reserve all indices up to and including this index */
293 if (last_hvc < index)
294 last_hvc = index;
295
296 /* check if we need to re-register the kernel console */
297 hvc_check_console(index);
298
299 return 0;
300}
301EXPORT_SYMBOL_GPL(hvc_instantiate);
302
303/* Wake the sleeping khvcd */
304void hvc_kick(void)
305{
306 hvc_kicked = 1;
307 wake_up_process(hvc_task);
308}
309EXPORT_SYMBOL_GPL(hvc_kick);
310
311static void hvc_unthrottle(struct tty_struct *tty)
312{
313 hvc_kick();
314}
315
316static int hvc_install(struct tty_driver *driver, struct tty_struct *tty)
317{
318 struct hvc_struct *hp;
319 int rc;
320
321 /* Auto increments kref reference if found. */
322 if (!(hp = hvc_get_by_index(tty->index)))
323 return -ENODEV;
324
325 tty->driver_data = hp;
326
327 rc = tty_port_install(&hp->port, driver, tty);
328 if (rc)
329 tty_port_put(&hp->port);
330 return rc;
331}
332
333/*
334 * The TTY interface won't be used until after the vio layer has exposed the vty
335 * adapter to the kernel.
336 */
337static int hvc_open(struct tty_struct *tty, struct file * filp)
338{
339 struct hvc_struct *hp = tty->driver_data;
340 unsigned long flags;
341 int rc = 0;
342
343 spin_lock_irqsave(&hp->port.lock, flags);
344 /* Check and then increment for fast path open. */
345 if (hp->port.count++ > 0) {
346 spin_unlock_irqrestore(&hp->port.lock, flags);
347 hvc_kick();
348 return 0;
349 } /* else count == 0 */
350 spin_unlock_irqrestore(&hp->port.lock, flags);
351
352 tty_port_tty_set(&hp->port, tty);
353
354 if (hp->ops->notifier_add)
355 rc = hp->ops->notifier_add(hp, hp->data);
356
357 /*
358 * If the notifier fails we return an error. The tty layer
359 * will call hvc_close() after a failed open but we don't want to clean
360 * up there so we'll clean up here and clear out the previously set
361 * tty fields and return the kref reference.
362 */
363 if (rc) {
364 tty_port_tty_set(&hp->port, NULL);
365 tty->driver_data = NULL;
366 tty_port_put(&hp->port);
367 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
368 } else
369 /* We are ready... raise DTR/RTS */
370 if (C_BAUD(tty))
371 if (hp->ops->dtr_rts)
372 hp->ops->dtr_rts(hp, 1);
373
374 /* Force wakeup of the polling thread */
375 hvc_kick();
376
377 return rc;
378}
379
380static void hvc_close(struct tty_struct *tty, struct file * filp)
381{
382 struct hvc_struct *hp;
383 unsigned long flags;
384
385 if (tty_hung_up_p(filp))
386 return;
387
388 /*
389 * No driver_data means that this close was issued after a failed
390 * hvc_open by the tty layer's release_dev() function and we can just
391 * exit cleanly because the kref reference wasn't made.
392 */
393 if (!tty->driver_data)
394 return;
395
396 hp = tty->driver_data;
397
398 spin_lock_irqsave(&hp->port.lock, flags);
399
400 if (--hp->port.count == 0) {
401 spin_unlock_irqrestore(&hp->port.lock, flags);
402 /* We are done with the tty pointer now. */
403 tty_port_tty_set(&hp->port, NULL);
404
405 if (C_HUPCL(tty))
406 if (hp->ops->dtr_rts)
407 hp->ops->dtr_rts(hp, 0);
408
409 if (hp->ops->notifier_del)
410 hp->ops->notifier_del(hp, hp->data);
411
412 /* cancel pending tty resize work */
413 cancel_work_sync(&hp->tty_resize);
414
415 /*
416 * Chain calls chars_in_buffer() and returns immediately if
417 * there is no buffered data otherwise sleeps on a wait queue
418 * waking periodically to check chars_in_buffer().
419 */
420 tty_wait_until_sent_from_close(tty, HVC_CLOSE_WAIT);
421 } else {
422 if (hp->port.count < 0)
423 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
424 hp->vtermno, hp->port.count);
425 spin_unlock_irqrestore(&hp->port.lock, flags);
426 }
427}
428
429static void hvc_cleanup(struct tty_struct *tty)
430{
431 struct hvc_struct *hp = tty->driver_data;
432
433 tty_port_put(&hp->port);
434}
435
436static void hvc_hangup(struct tty_struct *tty)
437{
438 struct hvc_struct *hp = tty->driver_data;
439 unsigned long flags;
440
441 if (!hp)
442 return;
443
444 /* cancel pending tty resize work */
445 cancel_work_sync(&hp->tty_resize);
446
447 spin_lock_irqsave(&hp->port.lock, flags);
448
449 /*
450 * The N_TTY line discipline has problems such that in a close vs
451 * open->hangup case this can be called after the final close so prevent
452 * that from happening for now.
453 */
454 if (hp->port.count <= 0) {
455 spin_unlock_irqrestore(&hp->port.lock, flags);
456 return;
457 }
458
459 hp->port.count = 0;
460 spin_unlock_irqrestore(&hp->port.lock, flags);
461 tty_port_tty_set(&hp->port, NULL);
462
463 hp->n_outbuf = 0;
464
465 if (hp->ops->notifier_hangup)
466 hp->ops->notifier_hangup(hp, hp->data);
467}
468
469/*
470 * Push buffered characters whether they were just recently buffered or waiting
471 * on a blocked hypervisor. Call this function with hp->lock held.
472 */
473static int hvc_push(struct hvc_struct *hp)
474{
475 int n;
476
477 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
478 if (n <= 0) {
479 if (n == 0 || n == -EAGAIN) {
480 hp->do_wakeup = 1;
481 return 0;
482 }
483 /* throw away output on error; this happens when
484 there is no session connected to the vterm. */
485 hp->n_outbuf = 0;
486 } else
487 hp->n_outbuf -= n;
488 if (hp->n_outbuf > 0)
489 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
490 else
491 hp->do_wakeup = 1;
492
493 return n;
494}
495
496static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
497{
498 struct hvc_struct *hp = tty->driver_data;
499 unsigned long flags;
500 int rsize, written = 0;
501
502 /* This write was probably executed during a tty close. */
503 if (!hp)
504 return -EPIPE;
505
506 /* FIXME what's this (unprotected) check for? */
507 if (hp->port.count <= 0)
508 return -EIO;
509
510 spin_lock_irqsave(&hp->lock, flags);
511
512 /* Push pending writes */
513 if (hp->n_outbuf > 0)
514 hvc_push(hp);
515
516 while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
517 if (rsize > count)
518 rsize = count;
519 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
520 count -= rsize;
521 buf += rsize;
522 hp->n_outbuf += rsize;
523 written += rsize;
524 hvc_push(hp);
525 }
526 spin_unlock_irqrestore(&hp->lock, flags);
527
528 /*
529 * Racy, but harmless, kick thread if there is still pending data.
530 */
531 if (hp->n_outbuf)
532 hvc_kick();
533
534 return written;
535}
536
537/**
538 * hvc_set_winsz() - Resize the hvc tty terminal window.
539 * @work: work structure.
540 *
541 * The routine shall not be called within an atomic context because it
542 * might sleep.
543 *
544 * Locking: hp->lock
545 */
546static void hvc_set_winsz(struct work_struct *work)
547{
548 struct hvc_struct *hp;
549 unsigned long hvc_flags;
550 struct tty_struct *tty;
551 struct winsize ws;
552
553 hp = container_of(work, struct hvc_struct, tty_resize);
554
555 tty = tty_port_tty_get(&hp->port);
556 if (!tty)
557 return;
558
559 spin_lock_irqsave(&hp->lock, hvc_flags);
560 ws = hp->ws;
561 spin_unlock_irqrestore(&hp->lock, hvc_flags);
562
563 tty_do_resize(tty, &ws);
564 tty_kref_put(tty);
565}
566
567/*
568 * This is actually a contract between the driver and the tty layer outlining
569 * how much write room the driver can guarantee will be sent OR BUFFERED. This
570 * driver MUST honor the return value.
571 */
572static int hvc_write_room(struct tty_struct *tty)
573{
574 struct hvc_struct *hp = tty->driver_data;
575
576 if (!hp)
577 return 0;
578
579 return hp->outbuf_size - hp->n_outbuf;
580}
581
582static int hvc_chars_in_buffer(struct tty_struct *tty)
583{
584 struct hvc_struct *hp = tty->driver_data;
585
586 if (!hp)
587 return 0;
588 return hp->n_outbuf;
589}
590
591/*
592 * timeout will vary between the MIN and MAX values defined here. By default
593 * and during console activity we will use a default MIN_TIMEOUT of 10. When
594 * the console is idle, we increase the timeout value on each pass through
595 * msleep until we reach the max. This may be noticeable as a brief (average
596 * one second) delay on the console before the console responds to input when
597 * there has been no input for some time.
598 */
599#define MIN_TIMEOUT (10)
600#define MAX_TIMEOUT (2000)
601static u32 timeout = MIN_TIMEOUT;
602
603#define HVC_POLL_READ 0x00000001
604#define HVC_POLL_WRITE 0x00000002
605
606int hvc_poll(struct hvc_struct *hp)
607{
608 struct tty_struct *tty;
609 int i, n, poll_mask = 0;
610 char buf[N_INBUF] __ALIGNED__;
611 unsigned long flags;
612 int read_total = 0;
613 int written_total = 0;
614
615 spin_lock_irqsave(&hp->lock, flags);
616
617 /* Push pending writes */
618 if (hp->n_outbuf > 0)
619 written_total = hvc_push(hp);
620
621 /* Reschedule us if still some write pending */
622 if (hp->n_outbuf > 0) {
623 poll_mask |= HVC_POLL_WRITE;
624 /* If hvc_push() was not able to write, sleep a few msecs */
625 timeout = (written_total) ? 0 : MIN_TIMEOUT;
626 }
627
628 /* No tty attached, just skip */
629 tty = tty_port_tty_get(&hp->port);
630 if (tty == NULL)
631 goto bail;
632
633 /* Now check if we can get data (are we throttled ?) */
634 if (test_bit(TTY_THROTTLED, &tty->flags))
635 goto throttled;
636
637 /* If we aren't notifier driven and aren't throttled, we always
638 * request a reschedule
639 */
640 if (!hp->irq_requested)
641 poll_mask |= HVC_POLL_READ;
642
643 /* Read data if any */
644 for (;;) {
645 int count = tty_buffer_request_room(&hp->port, N_INBUF);
646
647 /* If flip is full, just reschedule a later read */
648 if (count == 0) {
649 poll_mask |= HVC_POLL_READ;
650 break;
651 }
652
653 n = hp->ops->get_chars(hp->vtermno, buf, count);
654 if (n <= 0) {
655 /* Hangup the tty when disconnected from host */
656 if (n == -EPIPE) {
657 spin_unlock_irqrestore(&hp->lock, flags);
658 tty_hangup(tty);
659 spin_lock_irqsave(&hp->lock, flags);
660 } else if ( n == -EAGAIN ) {
661 /*
662 * Some back-ends can only ensure a certain min
663 * num of bytes read, which may be > 'count'.
664 * Let the tty clear the flip buff to make room.
665 */
666 poll_mask |= HVC_POLL_READ;
667 }
668 break;
669 }
670 for (i = 0; i < n; ++i) {
671#ifdef CONFIG_MAGIC_SYSRQ
672 if (hp->index == hvc_console.index) {
673 /* Handle the SysRq Hack */
674 /* XXX should support a sequence */
675 if (buf[i] == '\x0f') { /* ^O */
676 /* if ^O is pressed again, reset
677 * sysrq_pressed and flip ^O char */
678 sysrq_pressed = !sysrq_pressed;
679 if (sysrq_pressed)
680 continue;
681 } else if (sysrq_pressed) {
682 handle_sysrq(buf[i]);
683 sysrq_pressed = 0;
684 continue;
685 }
686 }
687#endif /* CONFIG_MAGIC_SYSRQ */
688 tty_insert_flip_char(&hp->port, buf[i], 0);
689 }
690
691 read_total += n;
692 }
693 throttled:
694 /* Wakeup write queue if necessary */
695 if (hp->do_wakeup) {
696 hp->do_wakeup = 0;
697 tty_wakeup(tty);
698 }
699 bail:
700 spin_unlock_irqrestore(&hp->lock, flags);
701
702 if (read_total) {
703 /* Activity is occurring, so reset the polling backoff value to
704 a minimum for performance. */
705 timeout = MIN_TIMEOUT;
706
707 tty_flip_buffer_push(&hp->port);
708 }
709 tty_kref_put(tty);
710
711 return poll_mask;
712}
713EXPORT_SYMBOL_GPL(hvc_poll);
714
715/**
716 * __hvc_resize() - Update terminal window size information.
717 * @hp: HVC console pointer
718 * @ws: Terminal window size structure
719 *
720 * Stores the specified window size information in the hvc structure of @hp.
721 * The function schedule the tty resize update.
722 *
723 * Locking: Locking free; the function MUST be called holding hp->lock
724 */
725void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
726{
727 hp->ws = ws;
728 schedule_work(&hp->tty_resize);
729}
730EXPORT_SYMBOL_GPL(__hvc_resize);
731
732/*
733 * This kthread is either polling or interrupt driven. This is determined by
734 * calling hvc_poll() who determines whether a console adapter support
735 * interrupts.
736 */
737static int khvcd(void *unused)
738{
739 int poll_mask;
740 struct hvc_struct *hp;
741
742 set_freezable();
743 do {
744 poll_mask = 0;
745 hvc_kicked = 0;
746 try_to_freeze();
747 wmb();
748 if (!cpus_are_in_xmon()) {
749 spin_lock(&hvc_structs_lock);
750 list_for_each_entry(hp, &hvc_structs, next) {
751 poll_mask |= hvc_poll(hp);
752 }
753 spin_unlock(&hvc_structs_lock);
754 } else
755 poll_mask |= HVC_POLL_READ;
756 if (hvc_kicked)
757 continue;
758 set_current_state(TASK_INTERRUPTIBLE);
759 if (!hvc_kicked) {
760 if (poll_mask == 0)
761 schedule();
762 else {
763 if (timeout < MAX_TIMEOUT)
764 timeout += (timeout >> 6) + 1;
765
766 msleep_interruptible(timeout);
767 }
768 }
769 __set_current_state(TASK_RUNNING);
770 } while (!kthread_should_stop());
771
772 return 0;
773}
774
775static int hvc_tiocmget(struct tty_struct *tty)
776{
777 struct hvc_struct *hp = tty->driver_data;
778
779 if (!hp || !hp->ops->tiocmget)
780 return -EINVAL;
781 return hp->ops->tiocmget(hp);
782}
783
784static int hvc_tiocmset(struct tty_struct *tty,
785 unsigned int set, unsigned int clear)
786{
787 struct hvc_struct *hp = tty->driver_data;
788
789 if (!hp || !hp->ops->tiocmset)
790 return -EINVAL;
791 return hp->ops->tiocmset(hp, set, clear);
792}
793
794#ifdef CONFIG_CONSOLE_POLL
795static int hvc_poll_init(struct tty_driver *driver, int line, char *options)
796{
797 return 0;
798}
799
800static int hvc_poll_get_char(struct tty_driver *driver, int line)
801{
802 struct tty_struct *tty = driver->ttys[0];
803 struct hvc_struct *hp = tty->driver_data;
804 int n;
805 char ch;
806
807 n = hp->ops->get_chars(hp->vtermno, &ch, 1);
808
809 if (n == 0)
810 return NO_POLL_CHAR;
811
812 return ch;
813}
814
815static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
816{
817 struct tty_struct *tty = driver->ttys[0];
818 struct hvc_struct *hp = tty->driver_data;
819 int n;
820
821 do {
822 n = hp->ops->put_chars(hp->vtermno, &ch, 1);
823 } while (n <= 0);
824}
825#endif
826
827static const struct tty_operations hvc_ops = {
828 .install = hvc_install,
829 .open = hvc_open,
830 .close = hvc_close,
831 .cleanup = hvc_cleanup,
832 .write = hvc_write,
833 .hangup = hvc_hangup,
834 .unthrottle = hvc_unthrottle,
835 .write_room = hvc_write_room,
836 .chars_in_buffer = hvc_chars_in_buffer,
837 .tiocmget = hvc_tiocmget,
838 .tiocmset = hvc_tiocmset,
839#ifdef CONFIG_CONSOLE_POLL
840 .poll_init = hvc_poll_init,
841 .poll_get_char = hvc_poll_get_char,
842 .poll_put_char = hvc_poll_put_char,
843#endif
844};
845
846static const struct tty_port_operations hvc_port_ops = {
847 .destruct = hvc_port_destruct,
848};
849
850struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
851 const struct hv_ops *ops,
852 int outbuf_size)
853{
854 struct hvc_struct *hp;
855 int i;
856
857 /* We wait until a driver actually comes along */
858 if (atomic_inc_not_zero(&hvc_needs_init)) {
859 int err = hvc_init();
860 if (err)
861 return ERR_PTR(err);
862 }
863
864 hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
865 GFP_KERNEL);
866 if (!hp)
867 return ERR_PTR(-ENOMEM);
868
869 hp->vtermno = vtermno;
870 hp->data = data;
871 hp->ops = ops;
872 hp->outbuf_size = outbuf_size;
873 hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
874
875 tty_port_init(&hp->port);
876 hp->port.ops = &hvc_port_ops;
877
878 INIT_WORK(&hp->tty_resize, hvc_set_winsz);
879 spin_lock_init(&hp->lock);
880 spin_lock(&hvc_structs_lock);
881
882 /*
883 * find index to use:
884 * see if this vterm id matches one registered for console.
885 */
886 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
887 if (vtermnos[i] == hp->vtermno &&
888 cons_ops[i] == hp->ops)
889 break;
890
891 /* no matching slot, just use a counter */
892 if (i >= MAX_NR_HVC_CONSOLES)
893 i = ++last_hvc;
894
895 hp->index = i;
896 cons_ops[i] = ops;
897 vtermnos[i] = vtermno;
898
899 list_add_tail(&(hp->next), &hvc_structs);
900 spin_unlock(&hvc_structs_lock);
901
902 /* check if we need to re-register the kernel console */
903 hvc_check_console(i);
904
905 return hp;
906}
907EXPORT_SYMBOL_GPL(hvc_alloc);
908
909int hvc_remove(struct hvc_struct *hp)
910{
911 unsigned long flags;
912 struct tty_struct *tty;
913
914 tty = tty_port_tty_get(&hp->port);
915
916 spin_lock_irqsave(&hp->lock, flags);
917 if (hp->index < MAX_NR_HVC_CONSOLES) {
918 console_lock();
919 vtermnos[hp->index] = -1;
920 cons_ops[hp->index] = NULL;
921 console_unlock();
922 }
923
924 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
925
926 spin_unlock_irqrestore(&hp->lock, flags);
927
928 /*
929 * We 'put' the instance that was grabbed when the kref instance
930 * was initialized using kref_init(). Let the last holder of this
931 * kref cause it to be removed, which will probably be the tty_vhangup
932 * below.
933 */
934 tty_port_put(&hp->port);
935
936 /*
937 * This function call will auto chain call hvc_hangup.
938 */
939 if (tty) {
940 tty_vhangup(tty);
941 tty_kref_put(tty);
942 }
943 return 0;
944}
945EXPORT_SYMBOL_GPL(hvc_remove);
946
947/* Driver initialization: called as soon as someone uses hvc_alloc(). */
948static int hvc_init(void)
949{
950 struct tty_driver *drv;
951 int err;
952
953 /* We need more than hvc_count adapters due to hotplug additions. */
954 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
955 if (!drv) {
956 err = -ENOMEM;
957 goto out;
958 }
959
960 drv->driver_name = "hvc";
961 drv->name = "hvc";
962 drv->major = HVC_MAJOR;
963 drv->minor_start = HVC_MINOR;
964 drv->type = TTY_DRIVER_TYPE_SYSTEM;
965 drv->init_termios = tty_std_termios;
966 drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
967 tty_set_operations(drv, &hvc_ops);
968
969 /* Always start the kthread because there can be hotplug vty adapters
970 * added later. */
971 hvc_task = kthread_run(khvcd, NULL, "khvcd");
972 if (IS_ERR(hvc_task)) {
973 printk(KERN_ERR "Couldn't create kthread for console.\n");
974 err = PTR_ERR(hvc_task);
975 goto put_tty;
976 }
977
978 err = tty_register_driver(drv);
979 if (err) {
980 printk(KERN_ERR "Couldn't register hvc console driver\n");
981 goto stop_thread;
982 }
983
984 /*
985 * Make sure tty is fully registered before allowing it to be
986 * found by hvc_console_device.
987 */
988 smp_mb();
989 hvc_driver = drv;
990 return 0;
991
992stop_thread:
993 kthread_stop(hvc_task);
994 hvc_task = NULL;
995put_tty:
996 put_tty_driver(drv);
997out:
998 return err;
999}
1000
1001/* This isn't particularly necessary due to this being a console driver
1002 * but it is nice to be thorough.
1003 */
1004static void __exit hvc_exit(void)
1005{
1006 if (hvc_driver) {
1007 kthread_stop(hvc_task);
1008
1009 tty_unregister_driver(hvc_driver);
1010 /* return tty_struct instances allocated in hvc_init(). */
1011 put_tty_driver(hvc_driver);
1012 unregister_console(&hvc_console);
1013 }
1014}
1015module_exit(hvc_exit);