Loading...
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/init.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 hp = hvc_get_by_index(tty->index);
323 if (!hp)
324 return -ENODEV;
325
326 tty->driver_data = hp;
327
328 rc = tty_port_install(&hp->port, driver, tty);
329 if (rc)
330 tty_port_put(&hp->port);
331 return rc;
332}
333
334/*
335 * The TTY interface won't be used until after the vio layer has exposed the vty
336 * adapter to the kernel.
337 */
338static int hvc_open(struct tty_struct *tty, struct file * filp)
339{
340 struct hvc_struct *hp = tty->driver_data;
341 unsigned long flags;
342 int rc = 0;
343
344 spin_lock_irqsave(&hp->port.lock, flags);
345 /* Check and then increment for fast path open. */
346 if (hp->port.count++ > 0) {
347 spin_unlock_irqrestore(&hp->port.lock, flags);
348 hvc_kick();
349 return 0;
350 } /* else count == 0 */
351 spin_unlock_irqrestore(&hp->port.lock, flags);
352
353 tty_port_tty_set(&hp->port, tty);
354
355 if (hp->ops->notifier_add)
356 rc = hp->ops->notifier_add(hp, hp->data);
357
358 /*
359 * If the notifier fails we return an error. The tty layer
360 * will call hvc_close() after a failed open but we don't want to clean
361 * up there so we'll clean up here and clear out the previously set
362 * tty fields and return the kref reference.
363 */
364 if (rc) {
365 tty_port_tty_set(&hp->port, NULL);
366 tty->driver_data = NULL;
367 tty_port_put(&hp->port);
368 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
369 } else
370 /* We are ready... raise DTR/RTS */
371 if (C_BAUD(tty))
372 if (hp->ops->dtr_rts)
373 hp->ops->dtr_rts(hp, 1);
374
375 /* Force wakeup of the polling thread */
376 hvc_kick();
377
378 return rc;
379}
380
381static void hvc_close(struct tty_struct *tty, struct file * filp)
382{
383 struct hvc_struct *hp;
384 unsigned long flags;
385
386 if (tty_hung_up_p(filp))
387 return;
388
389 /*
390 * No driver_data means that this close was issued after a failed
391 * hvc_open by the tty layer's release_dev() function and we can just
392 * exit cleanly because the kref reference wasn't made.
393 */
394 if (!tty->driver_data)
395 return;
396
397 hp = tty->driver_data;
398
399 spin_lock_irqsave(&hp->port.lock, flags);
400
401 if (--hp->port.count == 0) {
402 spin_unlock_irqrestore(&hp->port.lock, flags);
403 /* We are done with the tty pointer now. */
404 tty_port_tty_set(&hp->port, NULL);
405
406 if (C_HUPCL(tty))
407 if (hp->ops->dtr_rts)
408 hp->ops->dtr_rts(hp, 0);
409
410 if (hp->ops->notifier_del)
411 hp->ops->notifier_del(hp, hp->data);
412
413 /* cancel pending tty resize work */
414 cancel_work_sync(&hp->tty_resize);
415
416 /*
417 * Chain calls chars_in_buffer() and returns immediately if
418 * there is no buffered data otherwise sleeps on a wait queue
419 * waking periodically to check chars_in_buffer().
420 */
421 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
422 } else {
423 if (hp->port.count < 0)
424 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
425 hp->vtermno, hp->port.count);
426 spin_unlock_irqrestore(&hp->port.lock, flags);
427 }
428}
429
430static void hvc_cleanup(struct tty_struct *tty)
431{
432 struct hvc_struct *hp = tty->driver_data;
433
434 tty_port_put(&hp->port);
435}
436
437static void hvc_hangup(struct tty_struct *tty)
438{
439 struct hvc_struct *hp = tty->driver_data;
440 unsigned long flags;
441
442 if (!hp)
443 return;
444
445 /* cancel pending tty resize work */
446 cancel_work_sync(&hp->tty_resize);
447
448 spin_lock_irqsave(&hp->port.lock, flags);
449
450 /*
451 * The N_TTY line discipline has problems such that in a close vs
452 * open->hangup case this can be called after the final close so prevent
453 * that from happening for now.
454 */
455 if (hp->port.count <= 0) {
456 spin_unlock_irqrestore(&hp->port.lock, flags);
457 return;
458 }
459
460 hp->port.count = 0;
461 spin_unlock_irqrestore(&hp->port.lock, flags);
462 tty_port_tty_set(&hp->port, NULL);
463
464 hp->n_outbuf = 0;
465
466 if (hp->ops->notifier_hangup)
467 hp->ops->notifier_hangup(hp, hp->data);
468}
469
470/*
471 * Push buffered characters whether they were just recently buffered or waiting
472 * on a blocked hypervisor. Call this function with hp->lock held.
473 */
474static int hvc_push(struct hvc_struct *hp)
475{
476 int n;
477
478 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
479 if (n <= 0) {
480 if (n == 0 || n == -EAGAIN) {
481 hp->do_wakeup = 1;
482 return 0;
483 }
484 /* throw away output on error; this happens when
485 there is no session connected to the vterm. */
486 hp->n_outbuf = 0;
487 } else
488 hp->n_outbuf -= n;
489 if (hp->n_outbuf > 0)
490 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
491 else
492 hp->do_wakeup = 1;
493
494 return n;
495}
496
497static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
498{
499 struct hvc_struct *hp = tty->driver_data;
500 unsigned long flags;
501 int rsize, written = 0;
502
503 /* This write was probably executed during a tty close. */
504 if (!hp)
505 return -EPIPE;
506
507 /* FIXME what's this (unprotected) check for? */
508 if (hp->port.count <= 0)
509 return -EIO;
510
511 spin_lock_irqsave(&hp->lock, flags);
512
513 /* Push pending writes */
514 if (hp->n_outbuf > 0)
515 hvc_push(hp);
516
517 while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
518 if (rsize > count)
519 rsize = count;
520 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
521 count -= rsize;
522 buf += rsize;
523 hp->n_outbuf += rsize;
524 written += rsize;
525 hvc_push(hp);
526 }
527 spin_unlock_irqrestore(&hp->lock, flags);
528
529 /*
530 * Racy, but harmless, kick thread if there is still pending data.
531 */
532 if (hp->n_outbuf)
533 hvc_kick();
534
535 return written;
536}
537
538/**
539 * hvc_set_winsz() - Resize the hvc tty terminal window.
540 * @work: work structure.
541 *
542 * The routine shall not be called within an atomic context because it
543 * might sleep.
544 *
545 * Locking: hp->lock
546 */
547static void hvc_set_winsz(struct work_struct *work)
548{
549 struct hvc_struct *hp;
550 unsigned long hvc_flags;
551 struct tty_struct *tty;
552 struct winsize ws;
553
554 hp = container_of(work, struct hvc_struct, tty_resize);
555
556 tty = tty_port_tty_get(&hp->port);
557 if (!tty)
558 return;
559
560 spin_lock_irqsave(&hp->lock, hvc_flags);
561 ws = hp->ws;
562 spin_unlock_irqrestore(&hp->lock, hvc_flags);
563
564 tty_do_resize(tty, &ws);
565 tty_kref_put(tty);
566}
567
568/*
569 * This is actually a contract between the driver and the tty layer outlining
570 * how much write room the driver can guarantee will be sent OR BUFFERED. This
571 * driver MUST honor the return value.
572 */
573static int hvc_write_room(struct tty_struct *tty)
574{
575 struct hvc_struct *hp = tty->driver_data;
576
577 if (!hp)
578 return 0;
579
580 return hp->outbuf_size - hp->n_outbuf;
581}
582
583static int hvc_chars_in_buffer(struct tty_struct *tty)
584{
585 struct hvc_struct *hp = tty->driver_data;
586
587 if (!hp)
588 return 0;
589 return hp->n_outbuf;
590}
591
592/*
593 * timeout will vary between the MIN and MAX values defined here. By default
594 * and during console activity we will use a default MIN_TIMEOUT of 10. When
595 * the console is idle, we increase the timeout value on each pass through
596 * msleep until we reach the max. This may be noticeable as a brief (average
597 * one second) delay on the console before the console responds to input when
598 * there has been no input for some time.
599 */
600#define MIN_TIMEOUT (10)
601#define MAX_TIMEOUT (2000)
602static u32 timeout = MIN_TIMEOUT;
603
604#define HVC_POLL_READ 0x00000001
605#define HVC_POLL_WRITE 0x00000002
606
607int hvc_poll(struct hvc_struct *hp)
608{
609 struct tty_struct *tty;
610 int i, n, poll_mask = 0;
611 char buf[N_INBUF] __ALIGNED__;
612 unsigned long flags;
613 int read_total = 0;
614 int written_total = 0;
615
616 spin_lock_irqsave(&hp->lock, flags);
617
618 /* Push pending writes */
619 if (hp->n_outbuf > 0)
620 written_total = hvc_push(hp);
621
622 /* Reschedule us if still some write pending */
623 if (hp->n_outbuf > 0) {
624 poll_mask |= HVC_POLL_WRITE;
625 /* If hvc_push() was not able to write, sleep a few msecs */
626 timeout = (written_total) ? 0 : MIN_TIMEOUT;
627 }
628
629 /* No tty attached, just skip */
630 tty = tty_port_tty_get(&hp->port);
631 if (tty == NULL)
632 goto bail;
633
634 /* Now check if we can get data (are we throttled ?) */
635 if (test_bit(TTY_THROTTLED, &tty->flags))
636 goto throttled;
637
638 /* If we aren't notifier driven and aren't throttled, we always
639 * request a reschedule
640 */
641 if (!hp->irq_requested)
642 poll_mask |= HVC_POLL_READ;
643
644 /* Read data if any */
645 for (;;) {
646 int count = tty_buffer_request_room(&hp->port, N_INBUF);
647
648 /* If flip is full, just reschedule a later read */
649 if (count == 0) {
650 poll_mask |= HVC_POLL_READ;
651 break;
652 }
653
654 n = hp->ops->get_chars(hp->vtermno, buf, count);
655 if (n <= 0) {
656 /* Hangup the tty when disconnected from host */
657 if (n == -EPIPE) {
658 spin_unlock_irqrestore(&hp->lock, flags);
659 tty_hangup(tty);
660 spin_lock_irqsave(&hp->lock, flags);
661 } else if ( n == -EAGAIN ) {
662 /*
663 * Some back-ends can only ensure a certain min
664 * num of bytes read, which may be > 'count'.
665 * Let the tty clear the flip buff to make room.
666 */
667 poll_mask |= HVC_POLL_READ;
668 }
669 break;
670 }
671 for (i = 0; i < n; ++i) {
672#ifdef CONFIG_MAGIC_SYSRQ
673 if (hp->index == hvc_console.index) {
674 /* Handle the SysRq Hack */
675 /* XXX should support a sequence */
676 if (buf[i] == '\x0f') { /* ^O */
677 /* if ^O is pressed again, reset
678 * sysrq_pressed and flip ^O char */
679 sysrq_pressed = !sysrq_pressed;
680 if (sysrq_pressed)
681 continue;
682 } else if (sysrq_pressed) {
683 handle_sysrq(buf[i]);
684 sysrq_pressed = 0;
685 continue;
686 }
687 }
688#endif /* CONFIG_MAGIC_SYSRQ */
689 tty_insert_flip_char(&hp->port, buf[i], 0);
690 }
691
692 read_total += n;
693 }
694 throttled:
695 /* Wakeup write queue if necessary */
696 if (hp->do_wakeup) {
697 hp->do_wakeup = 0;
698 tty_wakeup(tty);
699 }
700 bail:
701 spin_unlock_irqrestore(&hp->lock, flags);
702
703 if (read_total) {
704 /* Activity is occurring, so reset the polling backoff value to
705 a minimum for performance. */
706 timeout = MIN_TIMEOUT;
707
708 tty_flip_buffer_push(&hp->port);
709 }
710 tty_kref_put(tty);
711
712 return poll_mask;
713}
714EXPORT_SYMBOL_GPL(hvc_poll);
715
716/**
717 * __hvc_resize() - Update terminal window size information.
718 * @hp: HVC console pointer
719 * @ws: Terminal window size structure
720 *
721 * Stores the specified window size information in the hvc structure of @hp.
722 * The function schedule the tty resize update.
723 *
724 * Locking: Locking free; the function MUST be called holding hp->lock
725 */
726void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
727{
728 hp->ws = ws;
729 schedule_work(&hp->tty_resize);
730}
731EXPORT_SYMBOL_GPL(__hvc_resize);
732
733/*
734 * This kthread is either polling or interrupt driven. This is determined by
735 * calling hvc_poll() who determines whether a console adapter support
736 * interrupts.
737 */
738static int khvcd(void *unused)
739{
740 int poll_mask;
741 struct hvc_struct *hp;
742
743 set_freezable();
744 do {
745 poll_mask = 0;
746 hvc_kicked = 0;
747 try_to_freeze();
748 wmb();
749 if (!cpus_are_in_xmon()) {
750 spin_lock(&hvc_structs_lock);
751 list_for_each_entry(hp, &hvc_structs, next) {
752 poll_mask |= hvc_poll(hp);
753 }
754 spin_unlock(&hvc_structs_lock);
755 } else
756 poll_mask |= HVC_POLL_READ;
757 if (hvc_kicked)
758 continue;
759 set_current_state(TASK_INTERRUPTIBLE);
760 if (!hvc_kicked) {
761 if (poll_mask == 0)
762 schedule();
763 else {
764 unsigned long j_timeout;
765
766 if (timeout < MAX_TIMEOUT)
767 timeout += (timeout >> 6) + 1;
768
769 /*
770 * We don't use msleep_interruptible otherwise
771 * "kick" will fail to wake us up
772 */
773 j_timeout = msecs_to_jiffies(timeout) + 1;
774 schedule_timeout_interruptible(j_timeout);
775 }
776 }
777 __set_current_state(TASK_RUNNING);
778 } while (!kthread_should_stop());
779
780 return 0;
781}
782
783static int hvc_tiocmget(struct tty_struct *tty)
784{
785 struct hvc_struct *hp = tty->driver_data;
786
787 if (!hp || !hp->ops->tiocmget)
788 return -EINVAL;
789 return hp->ops->tiocmget(hp);
790}
791
792static int hvc_tiocmset(struct tty_struct *tty,
793 unsigned int set, unsigned int clear)
794{
795 struct hvc_struct *hp = tty->driver_data;
796
797 if (!hp || !hp->ops->tiocmset)
798 return -EINVAL;
799 return hp->ops->tiocmset(hp, set, clear);
800}
801
802#ifdef CONFIG_CONSOLE_POLL
803static int hvc_poll_init(struct tty_driver *driver, int line, char *options)
804{
805 return 0;
806}
807
808static int hvc_poll_get_char(struct tty_driver *driver, int line)
809{
810 struct tty_struct *tty = driver->ttys[0];
811 struct hvc_struct *hp = tty->driver_data;
812 int n;
813 char ch;
814
815 n = hp->ops->get_chars(hp->vtermno, &ch, 1);
816
817 if (n == 0)
818 return NO_POLL_CHAR;
819
820 return ch;
821}
822
823static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
824{
825 struct tty_struct *tty = driver->ttys[0];
826 struct hvc_struct *hp = tty->driver_data;
827 int n;
828
829 do {
830 n = hp->ops->put_chars(hp->vtermno, &ch, 1);
831 } while (n <= 0);
832}
833#endif
834
835static const struct tty_operations hvc_ops = {
836 .install = hvc_install,
837 .open = hvc_open,
838 .close = hvc_close,
839 .cleanup = hvc_cleanup,
840 .write = hvc_write,
841 .hangup = hvc_hangup,
842 .unthrottle = hvc_unthrottle,
843 .write_room = hvc_write_room,
844 .chars_in_buffer = hvc_chars_in_buffer,
845 .tiocmget = hvc_tiocmget,
846 .tiocmset = hvc_tiocmset,
847#ifdef CONFIG_CONSOLE_POLL
848 .poll_init = hvc_poll_init,
849 .poll_get_char = hvc_poll_get_char,
850 .poll_put_char = hvc_poll_put_char,
851#endif
852};
853
854static const struct tty_port_operations hvc_port_ops = {
855 .destruct = hvc_port_destruct,
856};
857
858struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
859 const struct hv_ops *ops,
860 int outbuf_size)
861{
862 struct hvc_struct *hp;
863 int i;
864
865 /* We wait until a driver actually comes along */
866 if (atomic_inc_not_zero(&hvc_needs_init)) {
867 int err = hvc_init();
868 if (err)
869 return ERR_PTR(err);
870 }
871
872 hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
873 GFP_KERNEL);
874 if (!hp)
875 return ERR_PTR(-ENOMEM);
876
877 hp->vtermno = vtermno;
878 hp->data = data;
879 hp->ops = ops;
880 hp->outbuf_size = outbuf_size;
881 hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
882
883 tty_port_init(&hp->port);
884 hp->port.ops = &hvc_port_ops;
885
886 INIT_WORK(&hp->tty_resize, hvc_set_winsz);
887 spin_lock_init(&hp->lock);
888 spin_lock(&hvc_structs_lock);
889
890 /*
891 * find index to use:
892 * see if this vterm id matches one registered for console.
893 */
894 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
895 if (vtermnos[i] == hp->vtermno &&
896 cons_ops[i] == hp->ops)
897 break;
898
899 /* no matching slot, just use a counter */
900 if (i >= MAX_NR_HVC_CONSOLES)
901 i = ++last_hvc;
902
903 hp->index = i;
904 cons_ops[i] = ops;
905 vtermnos[i] = vtermno;
906
907 list_add_tail(&(hp->next), &hvc_structs);
908 spin_unlock(&hvc_structs_lock);
909
910 /* check if we need to re-register the kernel console */
911 hvc_check_console(i);
912
913 return hp;
914}
915EXPORT_SYMBOL_GPL(hvc_alloc);
916
917int hvc_remove(struct hvc_struct *hp)
918{
919 unsigned long flags;
920 struct tty_struct *tty;
921
922 tty = tty_port_tty_get(&hp->port);
923
924 spin_lock_irqsave(&hp->lock, flags);
925 if (hp->index < MAX_NR_HVC_CONSOLES) {
926 console_lock();
927 vtermnos[hp->index] = -1;
928 cons_ops[hp->index] = NULL;
929 console_unlock();
930 }
931
932 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
933
934 spin_unlock_irqrestore(&hp->lock, flags);
935
936 /*
937 * We 'put' the instance that was grabbed when the kref instance
938 * was initialized using kref_init(). Let the last holder of this
939 * kref cause it to be removed, which will probably be the tty_vhangup
940 * below.
941 */
942 tty_port_put(&hp->port);
943
944 /*
945 * This function call will auto chain call hvc_hangup.
946 */
947 if (tty) {
948 tty_vhangup(tty);
949 tty_kref_put(tty);
950 }
951 return 0;
952}
953EXPORT_SYMBOL_GPL(hvc_remove);
954
955/* Driver initialization: called as soon as someone uses hvc_alloc(). */
956static int hvc_init(void)
957{
958 struct tty_driver *drv;
959 int err;
960
961 /* We need more than hvc_count adapters due to hotplug additions. */
962 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
963 if (!drv) {
964 err = -ENOMEM;
965 goto out;
966 }
967
968 drv->driver_name = "hvc";
969 drv->name = "hvc";
970 drv->major = HVC_MAJOR;
971 drv->minor_start = HVC_MINOR;
972 drv->type = TTY_DRIVER_TYPE_SYSTEM;
973 drv->init_termios = tty_std_termios;
974 drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
975 tty_set_operations(drv, &hvc_ops);
976
977 /* Always start the kthread because there can be hotplug vty adapters
978 * added later. */
979 hvc_task = kthread_run(khvcd, NULL, "khvcd");
980 if (IS_ERR(hvc_task)) {
981 printk(KERN_ERR "Couldn't create kthread for console.\n");
982 err = PTR_ERR(hvc_task);
983 goto put_tty;
984 }
985
986 err = tty_register_driver(drv);
987 if (err) {
988 printk(KERN_ERR "Couldn't register hvc console driver\n");
989 goto stop_thread;
990 }
991
992 /*
993 * Make sure tty is fully registered before allowing it to be
994 * found by hvc_console_device.
995 */
996 smp_mb();
997 hvc_driver = drv;
998 return 0;
999
1000stop_thread:
1001 kthread_stop(hvc_task);
1002 hvc_task = NULL;
1003put_tty:
1004 put_tty_driver(drv);
1005out:
1006 return err;
1007}