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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// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
4 * Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM
5 * Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
6 * Copyright (C) 2004 IBM Corporation
7 *
8 * Additional Author(s):
9 * Ryan S. Arnold <rsa@us.ibm.com>
10 */
11
12#include <linux/console.h>
13#include <linux/cpumask.h>
14#include <linux/init.h>
15#include <linux/kbd_kern.h>
16#include <linux/kernel.h>
17#include <linux/kthread.h>
18#include <linux/list.h>
19#include <linux/major.h>
20#include <linux/atomic.h>
21#include <linux/sysrq.h>
22#include <linux/tty.h>
23#include <linux/tty_flip.h>
24#include <linux/sched.h>
25#include <linux/spinlock.h>
26#include <linux/delay.h>
27#include <linux/freezer.h>
28#include <linux/slab.h>
29#include <linux/serial_core.h>
30
31#include <linux/uaccess.h>
32
33#include "hvc_console.h"
34
35#define HVC_MAJOR 229
36#define HVC_MINOR 0
37
38/*
39 * Wait this long per iteration while trying to push buffered data to the
40 * hypervisor before allowing the tty to complete a close operation.
41 */
42#define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
43
44/*
45 * These sizes are most efficient for vio, because they are the
46 * native transfer size. We could make them selectable in the
47 * future to better deal with backends that want other buffer sizes.
48 */
49#define N_OUTBUF 16
50#define N_INBUF 16
51
52#define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
53
54static struct tty_driver *hvc_driver;
55static struct task_struct *hvc_task;
56
57/* Picks up late kicks after list walk but before schedule() */
58static int hvc_kicked;
59
60/* hvc_init is triggered from hvc_alloc, i.e. only when actually used */
61static atomic_t hvc_needs_init __read_mostly = ATOMIC_INIT(-1);
62
63static int hvc_init(void);
64
65#ifdef CONFIG_MAGIC_SYSRQ
66static int sysrq_pressed;
67#endif
68
69/* dynamic list of hvc_struct instances */
70static LIST_HEAD(hvc_structs);
71
72/*
73 * Protect the list of hvc_struct instances from inserts and removals during
74 * list traversal.
75 */
76static DEFINE_SPINLOCK(hvc_structs_lock);
77
78/*
79 * This value is used to assign a tty->index value to a hvc_struct based
80 * upon order of exposure via hvc_probe(), when we can not match it to
81 * a console candidate registered with hvc_instantiate().
82 */
83static int last_hvc = -1;
84
85/*
86 * Do not call this function with either the hvc_structs_lock or the hvc_struct
87 * lock held. If successful, this function increments the kref reference
88 * count against the target hvc_struct so it should be released when finished.
89 */
90static struct hvc_struct *hvc_get_by_index(int index)
91{
92 struct hvc_struct *hp;
93 unsigned long flags;
94
95 spin_lock(&hvc_structs_lock);
96
97 list_for_each_entry(hp, &hvc_structs, next) {
98 spin_lock_irqsave(&hp->lock, flags);
99 if (hp->index == index) {
100 tty_port_get(&hp->port);
101 spin_unlock_irqrestore(&hp->lock, flags);
102 spin_unlock(&hvc_structs_lock);
103 return hp;
104 }
105 spin_unlock_irqrestore(&hp->lock, flags);
106 }
107 hp = NULL;
108
109 spin_unlock(&hvc_structs_lock);
110 return hp;
111}
112
113
114/*
115 * Initial console vtermnos for console API usage prior to full console
116 * initialization. Any vty adapter outside this range will not have usable
117 * console interfaces but can still be used as a tty device. This has to be
118 * static because kmalloc will not work during early console init.
119 */
120static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
121static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
122 {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
123
124/*
125 * Console APIs, NOT TTY. These APIs are available immediately when
126 * hvc_console_setup() finds adapters.
127 */
128
129static void hvc_console_print(struct console *co, const char *b,
130 unsigned count)
131{
132 char c[N_OUTBUF] __ALIGNED__;
133 unsigned i = 0, n = 0;
134 int r, donecr = 0, index = co->index;
135
136 /* Console access attempt outside of acceptable console range. */
137 if (index >= MAX_NR_HVC_CONSOLES)
138 return;
139
140 /* This console adapter was removed so it is not usable. */
141 if (vtermnos[index] == -1)
142 return;
143
144 while (count > 0 || i > 0) {
145 if (count > 0 && i < sizeof(c)) {
146 if (b[n] == '\n' && !donecr) {
147 c[i++] = '\r';
148 donecr = 1;
149 } else {
150 c[i++] = b[n++];
151 donecr = 0;
152 --count;
153 }
154 } else {
155 r = cons_ops[index]->put_chars(vtermnos[index], c, i);
156 if (r <= 0) {
157 /* throw away characters on error
158 * but spin in case of -EAGAIN */
159 if (r != -EAGAIN)
160 i = 0;
161 } else if (r > 0) {
162 i -= r;
163 if (i > 0)
164 memmove(c, c+r, i);
165 }
166 }
167 }
168}
169
170static struct tty_driver *hvc_console_device(struct console *c, int *index)
171{
172 if (vtermnos[c->index] == -1)
173 return NULL;
174
175 *index = c->index;
176 return hvc_driver;
177}
178
179static int hvc_console_setup(struct console *co, char *options)
180{
181 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
182 return -ENODEV;
183
184 if (vtermnos[co->index] == -1)
185 return -ENODEV;
186
187 return 0;
188}
189
190static struct console hvc_console = {
191 .name = "hvc",
192 .write = hvc_console_print,
193 .device = hvc_console_device,
194 .setup = hvc_console_setup,
195 .flags = CON_PRINTBUFFER,
196 .index = -1,
197};
198
199/*
200 * Early console initialization. Precedes driver initialization.
201 *
202 * (1) we are first, and the user specified another driver
203 * -- index will remain -1
204 * (2) we are first and the user specified no driver
205 * -- index will be set to 0, then we will fail setup.
206 * (3) we are first and the user specified our driver
207 * -- index will be set to user specified driver, and we will fail
208 * (4) we are after driver, and this initcall will register us
209 * -- if the user didn't specify a driver then the console will match
210 *
211 * Note that for cases 2 and 3, we will match later when the io driver
212 * calls hvc_instantiate() and call register again.
213 */
214static int __init hvc_console_init(void)
215{
216 register_console(&hvc_console);
217 return 0;
218}
219console_initcall(hvc_console_init);
220
221/* callback when the kboject ref count reaches zero. */
222static void hvc_port_destruct(struct tty_port *port)
223{
224 struct hvc_struct *hp = container_of(port, struct hvc_struct, port);
225 unsigned long flags;
226
227 spin_lock(&hvc_structs_lock);
228
229 spin_lock_irqsave(&hp->lock, flags);
230 list_del(&(hp->next));
231 spin_unlock_irqrestore(&hp->lock, flags);
232
233 spin_unlock(&hvc_structs_lock);
234
235 kfree(hp);
236}
237
238static void hvc_check_console(int index)
239{
240 /* Already enabled, bail out */
241 if (hvc_console.flags & CON_ENABLED)
242 return;
243
244 /* If this index is what the user requested, then register
245 * now (setup won't fail at this point). It's ok to just
246 * call register again if previously .setup failed.
247 */
248 if (index == hvc_console.index)
249 register_console(&hvc_console);
250}
251
252/*
253 * hvc_instantiate() is an early console discovery method which locates
254 * consoles * prior to the vio subsystem discovering them. Hotplugged
255 * vty adapters do NOT get an hvc_instantiate() callback since they
256 * appear after early console init.
257 */
258int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
259{
260 struct hvc_struct *hp;
261
262 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
263 return -1;
264
265 if (vtermnos[index] != -1)
266 return -1;
267
268 /* make sure no no tty has been registered in this index */
269 hp = hvc_get_by_index(index);
270 if (hp) {
271 tty_port_put(&hp->port);
272 return -1;
273 }
274
275 vtermnos[index] = vtermno;
276 cons_ops[index] = ops;
277
278 /* reserve all indices up to and including this index */
279 if (last_hvc < index)
280 last_hvc = index;
281
282 /* check if we need to re-register the kernel console */
283 hvc_check_console(index);
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
302static int hvc_install(struct tty_driver *driver, struct tty_struct *tty)
303{
304 struct hvc_struct *hp;
305 int rc;
306
307 /* Auto increments kref reference if found. */
308 hp = hvc_get_by_index(tty->index);
309 if (!hp)
310 return -ENODEV;
311
312 tty->driver_data = hp;
313
314 rc = tty_port_install(&hp->port, driver, tty);
315 if (rc)
316 tty_port_put(&hp->port);
317 return rc;
318}
319
320/*
321 * The TTY interface won't be used until after the vio layer has exposed the vty
322 * adapter to the kernel.
323 */
324static int hvc_open(struct tty_struct *tty, struct file * filp)
325{
326 struct hvc_struct *hp = tty->driver_data;
327 unsigned long flags;
328 int rc = 0;
329
330 spin_lock_irqsave(&hp->port.lock, flags);
331 /* Check and then increment for fast path open. */
332 if (hp->port.count++ > 0) {
333 spin_unlock_irqrestore(&hp->port.lock, flags);
334 hvc_kick();
335 return 0;
336 } /* else count == 0 */
337 spin_unlock_irqrestore(&hp->port.lock, flags);
338
339 tty_port_tty_set(&hp->port, tty);
340
341 if (hp->ops->notifier_add)
342 rc = hp->ops->notifier_add(hp, hp->data);
343
344 /*
345 * If the notifier fails we return an error. The tty layer
346 * will call hvc_close() after a failed open but we don't want to clean
347 * up there so we'll clean up here and clear out the previously set
348 * tty fields and return the kref reference.
349 */
350 if (rc) {
351 tty_port_tty_set(&hp->port, NULL);
352 tty->driver_data = NULL;
353 tty_port_put(&hp->port);
354 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
355 } else
356 /* We are ready... raise DTR/RTS */
357 if (C_BAUD(tty))
358 if (hp->ops->dtr_rts)
359 hp->ops->dtr_rts(hp, 1);
360
361 /* Force wakeup of the polling thread */
362 hvc_kick();
363
364 return rc;
365}
366
367static void hvc_close(struct tty_struct *tty, struct file * filp)
368{
369 struct hvc_struct *hp;
370 unsigned long flags;
371
372 if (tty_hung_up_p(filp))
373 return;
374
375 /*
376 * No driver_data means that this close was issued after a failed
377 * hvc_open by the tty layer's release_dev() function and we can just
378 * exit cleanly because the kref reference wasn't made.
379 */
380 if (!tty->driver_data)
381 return;
382
383 hp = tty->driver_data;
384
385 spin_lock_irqsave(&hp->port.lock, flags);
386
387 if (--hp->port.count == 0) {
388 spin_unlock_irqrestore(&hp->port.lock, flags);
389 /* We are done with the tty pointer now. */
390 tty_port_tty_set(&hp->port, NULL);
391
392 if (C_HUPCL(tty))
393 if (hp->ops->dtr_rts)
394 hp->ops->dtr_rts(hp, 0);
395
396 if (hp->ops->notifier_del)
397 hp->ops->notifier_del(hp, hp->data);
398
399 /* cancel pending tty resize work */
400 cancel_work_sync(&hp->tty_resize);
401
402 /*
403 * Chain calls chars_in_buffer() and returns immediately if
404 * there is no buffered data otherwise sleeps on a wait queue
405 * waking periodically to check chars_in_buffer().
406 */
407 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
408 } else {
409 if (hp->port.count < 0)
410 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
411 hp->vtermno, hp->port.count);
412 spin_unlock_irqrestore(&hp->port.lock, flags);
413 }
414}
415
416static void hvc_cleanup(struct tty_struct *tty)
417{
418 struct hvc_struct *hp = tty->driver_data;
419
420 tty_port_put(&hp->port);
421}
422
423static void hvc_hangup(struct tty_struct *tty)
424{
425 struct hvc_struct *hp = tty->driver_data;
426 unsigned long flags;
427
428 if (!hp)
429 return;
430
431 /* cancel pending tty resize work */
432 cancel_work_sync(&hp->tty_resize);
433
434 spin_lock_irqsave(&hp->port.lock, flags);
435
436 /*
437 * The N_TTY line discipline has problems such that in a close vs
438 * open->hangup case this can be called after the final close so prevent
439 * that from happening for now.
440 */
441 if (hp->port.count <= 0) {
442 spin_unlock_irqrestore(&hp->port.lock, flags);
443 return;
444 }
445
446 hp->port.count = 0;
447 spin_unlock_irqrestore(&hp->port.lock, flags);
448 tty_port_tty_set(&hp->port, NULL);
449
450 hp->n_outbuf = 0;
451
452 if (hp->ops->notifier_hangup)
453 hp->ops->notifier_hangup(hp, hp->data);
454}
455
456/*
457 * Push buffered characters whether they were just recently buffered or waiting
458 * on a blocked hypervisor. Call this function with hp->lock held.
459 */
460static int hvc_push(struct hvc_struct *hp)
461{
462 int n;
463
464 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
465 if (n <= 0) {
466 if (n == 0 || n == -EAGAIN) {
467 hp->do_wakeup = 1;
468 return 0;
469 }
470 /* throw away output on error; this happens when
471 there is no session connected to the vterm. */
472 hp->n_outbuf = 0;
473 } else
474 hp->n_outbuf -= n;
475 if (hp->n_outbuf > 0)
476 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
477 else
478 hp->do_wakeup = 1;
479
480 return n;
481}
482
483static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
484{
485 struct hvc_struct *hp = tty->driver_data;
486 unsigned long flags;
487 int rsize, written = 0;
488
489 /* This write was probably executed during a tty close. */
490 if (!hp)
491 return -EPIPE;
492
493 /* FIXME what's this (unprotected) check for? */
494 if (hp->port.count <= 0)
495 return -EIO;
496
497 spin_lock_irqsave(&hp->lock, flags);
498
499 /* Push pending writes */
500 if (hp->n_outbuf > 0)
501 hvc_push(hp);
502
503 while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
504 if (rsize > count)
505 rsize = count;
506 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
507 count -= rsize;
508 buf += rsize;
509 hp->n_outbuf += rsize;
510 written += rsize;
511 hvc_push(hp);
512 }
513 spin_unlock_irqrestore(&hp->lock, flags);
514
515 /*
516 * Racy, but harmless, kick thread if there is still pending data.
517 */
518 if (hp->n_outbuf)
519 hvc_kick();
520
521 return written;
522}
523
524/**
525 * hvc_set_winsz() - Resize the hvc tty terminal window.
526 * @work: work structure.
527 *
528 * The routine shall not be called within an atomic context because it
529 * might sleep.
530 *
531 * Locking: hp->lock
532 */
533static void hvc_set_winsz(struct work_struct *work)
534{
535 struct hvc_struct *hp;
536 unsigned long hvc_flags;
537 struct tty_struct *tty;
538 struct winsize ws;
539
540 hp = container_of(work, struct hvc_struct, tty_resize);
541
542 tty = tty_port_tty_get(&hp->port);
543 if (!tty)
544 return;
545
546 spin_lock_irqsave(&hp->lock, hvc_flags);
547 ws = hp->ws;
548 spin_unlock_irqrestore(&hp->lock, hvc_flags);
549
550 tty_do_resize(tty, &ws);
551 tty_kref_put(tty);
552}
553
554/*
555 * This is actually a contract between the driver and the tty layer outlining
556 * how much write room the driver can guarantee will be sent OR BUFFERED. This
557 * driver MUST honor the return value.
558 */
559static int hvc_write_room(struct tty_struct *tty)
560{
561 struct hvc_struct *hp = tty->driver_data;
562
563 if (!hp)
564 return 0;
565
566 return hp->outbuf_size - hp->n_outbuf;
567}
568
569static int hvc_chars_in_buffer(struct tty_struct *tty)
570{
571 struct hvc_struct *hp = tty->driver_data;
572
573 if (!hp)
574 return 0;
575 return hp->n_outbuf;
576}
577
578/*
579 * timeout will vary between the MIN and MAX values defined here. By default
580 * and during console activity we will use a default MIN_TIMEOUT of 10. When
581 * the console is idle, we increase the timeout value on each pass through
582 * msleep until we reach the max. This may be noticeable as a brief (average
583 * one second) delay on the console before the console responds to input when
584 * there has been no input for some time.
585 */
586#define MIN_TIMEOUT (10)
587#define MAX_TIMEOUT (2000)
588static u32 timeout = MIN_TIMEOUT;
589
590#define HVC_POLL_READ 0x00000001
591#define HVC_POLL_WRITE 0x00000002
592
593int hvc_poll(struct hvc_struct *hp)
594{
595 struct tty_struct *tty;
596 int i, n, poll_mask = 0;
597 char buf[N_INBUF] __ALIGNED__;
598 unsigned long flags;
599 int read_total = 0;
600 int written_total = 0;
601
602 spin_lock_irqsave(&hp->lock, flags);
603
604 /* Push pending writes */
605 if (hp->n_outbuf > 0)
606 written_total = hvc_push(hp);
607
608 /* Reschedule us if still some write pending */
609 if (hp->n_outbuf > 0) {
610 poll_mask |= HVC_POLL_WRITE;
611 /* If hvc_push() was not able to write, sleep a few msecs */
612 timeout = (written_total) ? 0 : MIN_TIMEOUT;
613 }
614
615 /* No tty attached, just skip */
616 tty = tty_port_tty_get(&hp->port);
617 if (tty == NULL)
618 goto bail;
619
620 /* Now check if we can get data (are we throttled ?) */
621 if (tty_throttled(tty))
622 goto throttled;
623
624 /* If we aren't notifier driven and aren't throttled, we always
625 * request a reschedule
626 */
627 if (!hp->irq_requested)
628 poll_mask |= HVC_POLL_READ;
629
630 /* Read data if any */
631 for (;;) {
632 int count = tty_buffer_request_room(&hp->port, N_INBUF);
633
634 /* If flip is full, just reschedule a later read */
635 if (count == 0) {
636 poll_mask |= HVC_POLL_READ;
637 break;
638 }
639
640 n = hp->ops->get_chars(hp->vtermno, buf, count);
641 if (n <= 0) {
642 /* Hangup the tty when disconnected from host */
643 if (n == -EPIPE) {
644 spin_unlock_irqrestore(&hp->lock, flags);
645 tty_hangup(tty);
646 spin_lock_irqsave(&hp->lock, flags);
647 } else if ( n == -EAGAIN ) {
648 /*
649 * Some back-ends can only ensure a certain min
650 * num of bytes read, which may be > 'count'.
651 * Let the tty clear the flip buff to make room.
652 */
653 poll_mask |= HVC_POLL_READ;
654 }
655 break;
656 }
657 for (i = 0; i < n; ++i) {
658#ifdef CONFIG_MAGIC_SYSRQ
659 if (hp->index == hvc_console.index) {
660 /* Handle the SysRq Hack */
661 /* XXX should support a sequence */
662 if (buf[i] == '\x0f') { /* ^O */
663 /* if ^O is pressed again, reset
664 * sysrq_pressed and flip ^O char */
665 sysrq_pressed = !sysrq_pressed;
666 if (sysrq_pressed)
667 continue;
668 } else if (sysrq_pressed) {
669 handle_sysrq(buf[i]);
670 sysrq_pressed = 0;
671 continue;
672 }
673 }
674#endif /* CONFIG_MAGIC_SYSRQ */
675 tty_insert_flip_char(&hp->port, buf[i], 0);
676 }
677
678 read_total += n;
679 }
680 throttled:
681 /* Wakeup write queue if necessary */
682 if (hp->do_wakeup) {
683 hp->do_wakeup = 0;
684 tty_wakeup(tty);
685 }
686 bail:
687 spin_unlock_irqrestore(&hp->lock, flags);
688
689 if (read_total) {
690 /* Activity is occurring, so reset the polling backoff value to
691 a minimum for performance. */
692 timeout = MIN_TIMEOUT;
693
694 tty_flip_buffer_push(&hp->port);
695 }
696 tty_kref_put(tty);
697
698 return poll_mask;
699}
700EXPORT_SYMBOL_GPL(hvc_poll);
701
702/**
703 * __hvc_resize() - Update terminal window size information.
704 * @hp: HVC console pointer
705 * @ws: Terminal window size structure
706 *
707 * Stores the specified window size information in the hvc structure of @hp.
708 * The function schedule the tty resize update.
709 *
710 * Locking: Locking free; the function MUST be called holding hp->lock
711 */
712void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
713{
714 hp->ws = ws;
715 schedule_work(&hp->tty_resize);
716}
717EXPORT_SYMBOL_GPL(__hvc_resize);
718
719/*
720 * This kthread is either polling or interrupt driven. This is determined by
721 * calling hvc_poll() who determines whether a console adapter support
722 * interrupts.
723 */
724static int khvcd(void *unused)
725{
726 int poll_mask;
727 struct hvc_struct *hp;
728
729 set_freezable();
730 do {
731 poll_mask = 0;
732 hvc_kicked = 0;
733 try_to_freeze();
734 wmb();
735 if (!cpus_are_in_xmon()) {
736 spin_lock(&hvc_structs_lock);
737 list_for_each_entry(hp, &hvc_structs, next) {
738 poll_mask |= hvc_poll(hp);
739 }
740 spin_unlock(&hvc_structs_lock);
741 } else
742 poll_mask |= HVC_POLL_READ;
743 if (hvc_kicked)
744 continue;
745 set_current_state(TASK_INTERRUPTIBLE);
746 if (!hvc_kicked) {
747 if (poll_mask == 0)
748 schedule();
749 else {
750 unsigned long j_timeout;
751
752 if (timeout < MAX_TIMEOUT)
753 timeout += (timeout >> 6) + 1;
754
755 /*
756 * We don't use msleep_interruptible otherwise
757 * "kick" will fail to wake us up
758 */
759 j_timeout = msecs_to_jiffies(timeout) + 1;
760 schedule_timeout_interruptible(j_timeout);
761 }
762 }
763 __set_current_state(TASK_RUNNING);
764 } while (!kthread_should_stop());
765
766 return 0;
767}
768
769static int hvc_tiocmget(struct tty_struct *tty)
770{
771 struct hvc_struct *hp = tty->driver_data;
772
773 if (!hp || !hp->ops->tiocmget)
774 return -EINVAL;
775 return hp->ops->tiocmget(hp);
776}
777
778static int hvc_tiocmset(struct tty_struct *tty,
779 unsigned int set, unsigned int clear)
780{
781 struct hvc_struct *hp = tty->driver_data;
782
783 if (!hp || !hp->ops->tiocmset)
784 return -EINVAL;
785 return hp->ops->tiocmset(hp, set, clear);
786}
787
788#ifdef CONFIG_CONSOLE_POLL
789static int hvc_poll_init(struct tty_driver *driver, int line, char *options)
790{
791 return 0;
792}
793
794static int hvc_poll_get_char(struct tty_driver *driver, int line)
795{
796 struct tty_struct *tty = driver->ttys[0];
797 struct hvc_struct *hp = tty->driver_data;
798 int n;
799 char ch;
800
801 n = hp->ops->get_chars(hp->vtermno, &ch, 1);
802
803 if (n <= 0)
804 return NO_POLL_CHAR;
805
806 return ch;
807}
808
809static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
810{
811 struct tty_struct *tty = driver->ttys[0];
812 struct hvc_struct *hp = tty->driver_data;
813 int n;
814
815 do {
816 n = hp->ops->put_chars(hp->vtermno, &ch, 1);
817 } while (n <= 0);
818}
819#endif
820
821static const struct tty_operations hvc_ops = {
822 .install = hvc_install,
823 .open = hvc_open,
824 .close = hvc_close,
825 .cleanup = hvc_cleanup,
826 .write = hvc_write,
827 .hangup = hvc_hangup,
828 .unthrottle = hvc_unthrottle,
829 .write_room = hvc_write_room,
830 .chars_in_buffer = hvc_chars_in_buffer,
831 .tiocmget = hvc_tiocmget,
832 .tiocmset = hvc_tiocmset,
833#ifdef CONFIG_CONSOLE_POLL
834 .poll_init = hvc_poll_init,
835 .poll_get_char = hvc_poll_get_char,
836 .poll_put_char = hvc_poll_put_char,
837#endif
838};
839
840static const struct tty_port_operations hvc_port_ops = {
841 .destruct = hvc_port_destruct,
842};
843
844struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
845 const struct hv_ops *ops,
846 int outbuf_size)
847{
848 struct hvc_struct *hp;
849 int i;
850
851 /* We wait until a driver actually comes along */
852 if (atomic_inc_not_zero(&hvc_needs_init)) {
853 int err = hvc_init();
854 if (err)
855 return ERR_PTR(err);
856 }
857
858 hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
859 GFP_KERNEL);
860 if (!hp)
861 return ERR_PTR(-ENOMEM);
862
863 hp->vtermno = vtermno;
864 hp->data = data;
865 hp->ops = ops;
866 hp->outbuf_size = outbuf_size;
867 hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
868
869 tty_port_init(&hp->port);
870 hp->port.ops = &hvc_port_ops;
871
872 INIT_WORK(&hp->tty_resize, hvc_set_winsz);
873 spin_lock_init(&hp->lock);
874 spin_lock(&hvc_structs_lock);
875
876 /*
877 * find index to use:
878 * see if this vterm id matches one registered for console.
879 */
880 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
881 if (vtermnos[i] == hp->vtermno &&
882 cons_ops[i] == hp->ops)
883 break;
884
885 /* no matching slot, just use a counter */
886 if (i >= MAX_NR_HVC_CONSOLES)
887 i = ++last_hvc;
888
889 hp->index = i;
890 cons_ops[i] = ops;
891 vtermnos[i] = vtermno;
892
893 list_add_tail(&(hp->next), &hvc_structs);
894 spin_unlock(&hvc_structs_lock);
895
896 /* check if we need to re-register the kernel console */
897 hvc_check_console(i);
898
899 return hp;
900}
901EXPORT_SYMBOL_GPL(hvc_alloc);
902
903int hvc_remove(struct hvc_struct *hp)
904{
905 unsigned long flags;
906 struct tty_struct *tty;
907
908 tty = tty_port_tty_get(&hp->port);
909
910 console_lock();
911 spin_lock_irqsave(&hp->lock, flags);
912 if (hp->index < MAX_NR_HVC_CONSOLES) {
913 vtermnos[hp->index] = -1;
914 cons_ops[hp->index] = NULL;
915 }
916
917 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
918
919 spin_unlock_irqrestore(&hp->lock, flags);
920 console_unlock();
921
922 /*
923 * We 'put' the instance that was grabbed when the kref instance
924 * was initialized using kref_init(). Let the last holder of this
925 * kref cause it to be removed, which will probably be the tty_vhangup
926 * below.
927 */
928 tty_port_put(&hp->port);
929
930 /*
931 * This function call will auto chain call hvc_hangup.
932 */
933 if (tty) {
934 tty_vhangup(tty);
935 tty_kref_put(tty);
936 }
937 return 0;
938}
939EXPORT_SYMBOL_GPL(hvc_remove);
940
941/* Driver initialization: called as soon as someone uses hvc_alloc(). */
942static int hvc_init(void)
943{
944 struct tty_driver *drv;
945 int err;
946
947 /* We need more than hvc_count adapters due to hotplug additions. */
948 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
949 if (!drv) {
950 err = -ENOMEM;
951 goto out;
952 }
953
954 drv->driver_name = "hvc";
955 drv->name = "hvc";
956 drv->major = HVC_MAJOR;
957 drv->minor_start = HVC_MINOR;
958 drv->type = TTY_DRIVER_TYPE_SYSTEM;
959 drv->init_termios = tty_std_termios;
960 drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
961 tty_set_operations(drv, &hvc_ops);
962
963 /* Always start the kthread because there can be hotplug vty adapters
964 * added later. */
965 hvc_task = kthread_run(khvcd, NULL, "khvcd");
966 if (IS_ERR(hvc_task)) {
967 printk(KERN_ERR "Couldn't create kthread for console.\n");
968 err = PTR_ERR(hvc_task);
969 goto put_tty;
970 }
971
972 err = tty_register_driver(drv);
973 if (err) {
974 printk(KERN_ERR "Couldn't register hvc console driver\n");
975 goto stop_thread;
976 }
977
978 /*
979 * Make sure tty is fully registered before allowing it to be
980 * found by hvc_console_device.
981 */
982 smp_mb();
983 hvc_driver = drv;
984 return 0;
985
986stop_thread:
987 kthread_stop(hvc_task);
988 hvc_task = NULL;
989put_tty:
990 put_tty_driver(drv);
991out:
992 return err;
993}