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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__(L1_CACHE_BYTES)))
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_MUTEX(hvc_structs_mutex);
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_mutex 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 mutex_lock(&hvc_structs_mutex);
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 mutex_unlock(&hvc_structs_mutex);
103 return hp;
104 }
105 spin_unlock_irqrestore(&hp->lock, flags);
106 }
107 hp = NULL;
108 mutex_unlock(&hvc_structs_mutex);
109
110 return hp;
111}
112
113static int __hvc_flush(const struct hv_ops *ops, uint32_t vtermno, bool wait)
114{
115 if (wait)
116 might_sleep();
117
118 if (ops->flush)
119 return ops->flush(vtermno, wait);
120 return 0;
121}
122
123static int hvc_console_flush(const struct hv_ops *ops, uint32_t vtermno)
124{
125 return __hvc_flush(ops, vtermno, false);
126}
127
128/*
129 * Wait for the console to flush before writing more to it. This sleeps.
130 */
131static int hvc_flush(struct hvc_struct *hp)
132{
133 return __hvc_flush(hp->ops, hp->vtermno, true);
134}
135
136/*
137 * Initial console vtermnos for console API usage prior to full console
138 * initialization. Any vty adapter outside this range will not have usable
139 * console interfaces but can still be used as a tty device. This has to be
140 * static because kmalloc will not work during early console init.
141 */
142static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
143static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
144 {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
145
146/*
147 * Console APIs, NOT TTY. These APIs are available immediately when
148 * hvc_console_setup() finds adapters.
149 */
150
151static void hvc_console_print(struct console *co, const char *b,
152 unsigned count)
153{
154 char c[N_OUTBUF] __ALIGNED__;
155 unsigned i = 0, n = 0;
156 int r, donecr = 0, index = co->index;
157
158 /* Console access attempt outside of acceptable console range. */
159 if (index >= MAX_NR_HVC_CONSOLES)
160 return;
161
162 /* This console adapter was removed so it is not usable. */
163 if (vtermnos[index] == -1)
164 return;
165
166 while (count > 0 || i > 0) {
167 if (count > 0 && i < sizeof(c)) {
168 if (b[n] == '\n' && !donecr) {
169 c[i++] = '\r';
170 donecr = 1;
171 } else {
172 c[i++] = b[n++];
173 donecr = 0;
174 --count;
175 }
176 } else {
177 r = cons_ops[index]->put_chars(vtermnos[index], c, i);
178 if (r <= 0) {
179 /* throw away characters on error
180 * but spin in case of -EAGAIN */
181 if (r != -EAGAIN) {
182 i = 0;
183 } else {
184 hvc_console_flush(cons_ops[index],
185 vtermnos[index]);
186 }
187 } else if (r > 0) {
188 i -= r;
189 if (i > 0)
190 memmove(c, c+r, i);
191 }
192 }
193 }
194 hvc_console_flush(cons_ops[index], vtermnos[index]);
195}
196
197static struct tty_driver *hvc_console_device(struct console *c, int *index)
198{
199 if (vtermnos[c->index] == -1)
200 return NULL;
201
202 *index = c->index;
203 return hvc_driver;
204}
205
206static int hvc_console_setup(struct console *co, char *options)
207{
208 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
209 return -ENODEV;
210
211 if (vtermnos[co->index] == -1)
212 return -ENODEV;
213
214 return 0;
215}
216
217static struct console hvc_console = {
218 .name = "hvc",
219 .write = hvc_console_print,
220 .device = hvc_console_device,
221 .setup = hvc_console_setup,
222 .flags = CON_PRINTBUFFER,
223 .index = -1,
224};
225
226/*
227 * Early console initialization. Precedes driver initialization.
228 *
229 * (1) we are first, and the user specified another driver
230 * -- index will remain -1
231 * (2) we are first and the user specified no driver
232 * -- index will be set to 0, then we will fail setup.
233 * (3) we are first and the user specified our driver
234 * -- index will be set to user specified driver, and we will fail
235 * (4) we are after driver, and this initcall will register us
236 * -- if the user didn't specify a driver then the console will match
237 *
238 * Note that for cases 2 and 3, we will match later when the io driver
239 * calls hvc_instantiate() and call register again.
240 */
241static int __init hvc_console_init(void)
242{
243 register_console(&hvc_console);
244 return 0;
245}
246console_initcall(hvc_console_init);
247
248/* callback when the kboject ref count reaches zero. */
249static void hvc_port_destruct(struct tty_port *port)
250{
251 struct hvc_struct *hp = container_of(port, struct hvc_struct, port);
252 unsigned long flags;
253
254 mutex_lock(&hvc_structs_mutex);
255
256 spin_lock_irqsave(&hp->lock, flags);
257 list_del(&(hp->next));
258 spin_unlock_irqrestore(&hp->lock, flags);
259
260 mutex_unlock(&hvc_structs_mutex);
261
262 kfree(hp);
263}
264
265static void hvc_check_console(int index)
266{
267 /* Already registered, bail out */
268 if (console_is_registered(&hvc_console))
269 return;
270
271 /* If this index is what the user requested, then register
272 * now (setup won't fail at this point). It's ok to just
273 * call register again if previously .setup failed.
274 */
275 if (index == hvc_console.index)
276 register_console(&hvc_console);
277}
278
279/*
280 * hvc_instantiate() is an early console discovery method which locates
281 * consoles * prior to the vio subsystem discovering them. Hotplugged
282 * vty adapters do NOT get an hvc_instantiate() callback since they
283 * appear after early console init.
284 */
285int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
286{
287 struct hvc_struct *hp;
288
289 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
290 return -1;
291
292 if (vtermnos[index] != -1)
293 return -1;
294
295 /* make sure no tty has been registered in this index */
296 hp = hvc_get_by_index(index);
297 if (hp) {
298 tty_port_put(&hp->port);
299 return -1;
300 }
301
302 vtermnos[index] = vtermno;
303 cons_ops[index] = ops;
304
305 /* check if we need to re-register the kernel console */
306 hvc_check_console(index);
307
308 return 0;
309}
310EXPORT_SYMBOL_GPL(hvc_instantiate);
311
312/* Wake the sleeping khvcd */
313void hvc_kick(void)
314{
315 hvc_kicked = 1;
316 wake_up_process(hvc_task);
317}
318EXPORT_SYMBOL_GPL(hvc_kick);
319
320static void hvc_unthrottle(struct tty_struct *tty)
321{
322 hvc_kick();
323}
324
325static int hvc_install(struct tty_driver *driver, struct tty_struct *tty)
326{
327 struct hvc_struct *hp;
328 int rc;
329
330 /* Auto increments kref reference if found. */
331 hp = hvc_get_by_index(tty->index);
332 if (!hp)
333 return -ENODEV;
334
335 tty->driver_data = hp;
336
337 rc = tty_port_install(&hp->port, driver, tty);
338 if (rc)
339 tty_port_put(&hp->port);
340 return rc;
341}
342
343/*
344 * The TTY interface won't be used until after the vio layer has exposed the vty
345 * adapter to the kernel.
346 */
347static int hvc_open(struct tty_struct *tty, struct file * filp)
348{
349 struct hvc_struct *hp = tty->driver_data;
350 unsigned long flags;
351 int rc = 0;
352
353 spin_lock_irqsave(&hp->port.lock, flags);
354 /* Check and then increment for fast path open. */
355 if (hp->port.count++ > 0) {
356 spin_unlock_irqrestore(&hp->port.lock, flags);
357 hvc_kick();
358 return 0;
359 } /* else count == 0 */
360 spin_unlock_irqrestore(&hp->port.lock, flags);
361
362 tty_port_tty_set(&hp->port, tty);
363
364 if (hp->ops->notifier_add)
365 rc = hp->ops->notifier_add(hp, hp->data);
366
367 /*
368 * If the notifier fails we return an error. The tty layer
369 * will call hvc_close() after a failed open but we don't want to clean
370 * up there so we'll clean up here and clear out the previously set
371 * tty fields and return the kref reference.
372 */
373 if (rc) {
374 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
375 } else {
376 /* We are ready... raise DTR/RTS */
377 if (C_BAUD(tty))
378 if (hp->ops->dtr_rts)
379 hp->ops->dtr_rts(hp, true);
380 tty_port_set_initialized(&hp->port, true);
381 }
382
383 /* Force wakeup of the polling thread */
384 hvc_kick();
385
386 return rc;
387}
388
389static void hvc_close(struct tty_struct *tty, struct file * filp)
390{
391 struct hvc_struct *hp = tty->driver_data;
392 unsigned long flags;
393
394 if (tty_hung_up_p(filp))
395 return;
396
397 spin_lock_irqsave(&hp->port.lock, flags);
398
399 if (--hp->port.count == 0) {
400 spin_unlock_irqrestore(&hp->port.lock, flags);
401 /* We are done with the tty pointer now. */
402 tty_port_tty_set(&hp->port, NULL);
403
404 if (!tty_port_initialized(&hp->port))
405 return;
406
407 if (C_HUPCL(tty))
408 if (hp->ops->dtr_rts)
409 hp->ops->dtr_rts(hp, false);
410
411 if (hp->ops->notifier_del)
412 hp->ops->notifier_del(hp, hp->data);
413
414 /* cancel pending tty resize work */
415 cancel_work_sync(&hp->tty_resize);
416
417 /*
418 * Chain calls chars_in_buffer() and returns immediately if
419 * there is no buffered data otherwise sleeps on a wait queue
420 * waking periodically to check chars_in_buffer().
421 */
422 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
423 tty_port_set_initialized(&hp->port, false);
424 } else {
425 if (hp->port.count < 0)
426 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
427 hp->vtermno, hp->port.count);
428 spin_unlock_irqrestore(&hp->port.lock, flags);
429 }
430}
431
432static void hvc_cleanup(struct tty_struct *tty)
433{
434 struct hvc_struct *hp = tty->driver_data;
435
436 tty_port_put(&hp->port);
437}
438
439static void hvc_hangup(struct tty_struct *tty)
440{
441 struct hvc_struct *hp = tty->driver_data;
442 unsigned long flags;
443
444 if (!hp)
445 return;
446
447 /* cancel pending tty resize work */
448 cancel_work_sync(&hp->tty_resize);
449
450 spin_lock_irqsave(&hp->port.lock, flags);
451
452 /*
453 * The N_TTY line discipline has problems such that in a close vs
454 * open->hangup case this can be called after the final close so prevent
455 * that from happening for now.
456 */
457 if (hp->port.count <= 0) {
458 spin_unlock_irqrestore(&hp->port.lock, flags);
459 return;
460 }
461
462 hp->port.count = 0;
463 spin_unlock_irqrestore(&hp->port.lock, flags);
464 tty_port_tty_set(&hp->port, NULL);
465
466 hp->n_outbuf = 0;
467
468 if (hp->ops->notifier_hangup)
469 hp->ops->notifier_hangup(hp, hp->data);
470}
471
472/*
473 * Push buffered characters whether they were just recently buffered or waiting
474 * on a blocked hypervisor. Call this function with hp->lock held.
475 */
476static int hvc_push(struct hvc_struct *hp)
477{
478 int n;
479
480 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
481 if (n <= 0) {
482 if (n == 0 || n == -EAGAIN) {
483 hp->do_wakeup = 1;
484 return 0;
485 }
486 /* throw away output on error; this happens when
487 there is no session connected to the vterm. */
488 hp->n_outbuf = 0;
489 } else
490 hp->n_outbuf -= n;
491 if (hp->n_outbuf > 0)
492 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
493 else
494 hp->do_wakeup = 1;
495
496 return n;
497}
498
499static ssize_t hvc_write(struct tty_struct *tty, const u8 *buf, size_t count)
500{
501 struct hvc_struct *hp = tty->driver_data;
502 unsigned long flags;
503 size_t rsize, written = 0;
504
505 /* This write was probably executed during a tty close. */
506 if (!hp)
507 return -EPIPE;
508
509 /* FIXME what's this (unprotected) check for? */
510 if (hp->port.count <= 0)
511 return -EIO;
512
513 while (count > 0) {
514 int ret = 0;
515
516 spin_lock_irqsave(&hp->lock, flags);
517
518 rsize = hp->outbuf_size - hp->n_outbuf;
519
520 if (rsize) {
521 if (rsize > count)
522 rsize = count;
523 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
524 count -= rsize;
525 buf += rsize;
526 hp->n_outbuf += rsize;
527 written += rsize;
528 }
529
530 if (hp->n_outbuf > 0)
531 ret = hvc_push(hp);
532
533 spin_unlock_irqrestore(&hp->lock, flags);
534
535 if (!ret)
536 break;
537
538 if (count) {
539 if (hp->n_outbuf > 0)
540 hvc_flush(hp);
541 cond_resched();
542 }
543 }
544
545 /*
546 * Racy, but harmless, kick thread if there is still pending data.
547 */
548 if (hp->n_outbuf)
549 hvc_kick();
550
551 return written;
552}
553
554/**
555 * hvc_set_winsz() - Resize the hvc tty terminal window.
556 * @work: work structure.
557 *
558 * The routine shall not be called within an atomic context because it
559 * might sleep.
560 *
561 * Locking: hp->lock
562 */
563static void hvc_set_winsz(struct work_struct *work)
564{
565 struct hvc_struct *hp;
566 unsigned long hvc_flags;
567 struct tty_struct *tty;
568 struct winsize ws;
569
570 hp = container_of(work, struct hvc_struct, tty_resize);
571
572 tty = tty_port_tty_get(&hp->port);
573 if (!tty)
574 return;
575
576 spin_lock_irqsave(&hp->lock, hvc_flags);
577 ws = hp->ws;
578 spin_unlock_irqrestore(&hp->lock, hvc_flags);
579
580 tty_do_resize(tty, &ws);
581 tty_kref_put(tty);
582}
583
584/*
585 * This is actually a contract between the driver and the tty layer outlining
586 * how much write room the driver can guarantee will be sent OR BUFFERED. This
587 * driver MUST honor the return value.
588 */
589static unsigned int hvc_write_room(struct tty_struct *tty)
590{
591 struct hvc_struct *hp = tty->driver_data;
592
593 if (!hp)
594 return 0;
595
596 return hp->outbuf_size - hp->n_outbuf;
597}
598
599static unsigned int hvc_chars_in_buffer(struct tty_struct *tty)
600{
601 struct hvc_struct *hp = tty->driver_data;
602
603 if (!hp)
604 return 0;
605 return hp->n_outbuf;
606}
607
608/*
609 * timeout will vary between the MIN and MAX values defined here. By default
610 * and during console activity we will use a default MIN_TIMEOUT of 10. When
611 * the console is idle, we increase the timeout value on each pass through
612 * msleep until we reach the max. This may be noticeable as a brief (average
613 * one second) delay on the console before the console responds to input when
614 * there has been no input for some time.
615 */
616#define MIN_TIMEOUT (10)
617#define MAX_TIMEOUT (2000)
618static u32 timeout = MIN_TIMEOUT;
619
620/*
621 * Maximum number of bytes to get from the console driver if hvc_poll is
622 * called from driver (and can't sleep). Any more than this and we break
623 * and start polling with khvcd. This value was derived from an OpenBMC
624 * console with the OPAL driver that results in about 0.25ms interrupts off
625 * latency.
626 */
627#define HVC_ATOMIC_READ_MAX 128
628
629#define HVC_POLL_READ 0x00000001
630#define HVC_POLL_WRITE 0x00000002
631
632static int __hvc_poll(struct hvc_struct *hp, bool may_sleep)
633{
634 struct tty_struct *tty;
635 int i, n, count, poll_mask = 0;
636 char buf[N_INBUF] __ALIGNED__;
637 unsigned long flags;
638 int read_total = 0;
639 int written_total = 0;
640
641 spin_lock_irqsave(&hp->lock, flags);
642
643 /* Push pending writes */
644 if (hp->n_outbuf > 0)
645 written_total = hvc_push(hp);
646
647 /* Reschedule us if still some write pending */
648 if (hp->n_outbuf > 0) {
649 poll_mask |= HVC_POLL_WRITE;
650 /* If hvc_push() was not able to write, sleep a few msecs */
651 timeout = (written_total) ? 0 : MIN_TIMEOUT;
652 }
653
654 if (may_sleep) {
655 spin_unlock_irqrestore(&hp->lock, flags);
656 cond_resched();
657 spin_lock_irqsave(&hp->lock, flags);
658 }
659
660 /* No tty attached, just skip */
661 tty = tty_port_tty_get(&hp->port);
662 if (tty == NULL)
663 goto bail;
664
665 /* Now check if we can get data (are we throttled ?) */
666 if (tty_throttled(tty))
667 goto out;
668
669 /* If we aren't notifier driven and aren't throttled, we always
670 * request a reschedule
671 */
672 if (!hp->irq_requested)
673 poll_mask |= HVC_POLL_READ;
674
675 read_again:
676 /* Read data if any */
677 count = tty_buffer_request_room(&hp->port, N_INBUF);
678
679 /* If flip is full, just reschedule a later read */
680 if (count == 0) {
681 poll_mask |= HVC_POLL_READ;
682 goto out;
683 }
684
685 n = hp->ops->get_chars(hp->vtermno, buf, count);
686 if (n <= 0) {
687 /* Hangup the tty when disconnected from host */
688 if (n == -EPIPE) {
689 spin_unlock_irqrestore(&hp->lock, flags);
690 tty_hangup(tty);
691 spin_lock_irqsave(&hp->lock, flags);
692 } else if ( n == -EAGAIN ) {
693 /*
694 * Some back-ends can only ensure a certain min
695 * num of bytes read, which may be > 'count'.
696 * Let the tty clear the flip buff to make room.
697 */
698 poll_mask |= HVC_POLL_READ;
699 }
700 goto out;
701 }
702
703 for (i = 0; i < n; ++i) {
704#ifdef CONFIG_MAGIC_SYSRQ
705 if (hp->index == hvc_console.index) {
706 /* Handle the SysRq Hack */
707 /* XXX should support a sequence */
708 if (buf[i] == '\x0f') { /* ^O */
709 /* if ^O is pressed again, reset
710 * sysrq_pressed and flip ^O char */
711 sysrq_pressed = !sysrq_pressed;
712 if (sysrq_pressed)
713 continue;
714 } else if (sysrq_pressed) {
715 handle_sysrq(buf[i]);
716 sysrq_pressed = 0;
717 continue;
718 }
719 }
720#endif /* CONFIG_MAGIC_SYSRQ */
721 tty_insert_flip_char(&hp->port, buf[i], 0);
722 }
723 read_total += n;
724
725 if (may_sleep) {
726 /* Keep going until the flip is full */
727 spin_unlock_irqrestore(&hp->lock, flags);
728 cond_resched();
729 spin_lock_irqsave(&hp->lock, flags);
730 goto read_again;
731 } else if (read_total < HVC_ATOMIC_READ_MAX) {
732 /* Break and defer if it's a large read in atomic */
733 goto read_again;
734 }
735
736 /*
737 * Latency break, schedule another poll immediately.
738 */
739 poll_mask |= HVC_POLL_READ;
740
741 out:
742 /* Wakeup write queue if necessary */
743 if (hp->do_wakeup) {
744 hp->do_wakeup = 0;
745 tty_wakeup(tty);
746 }
747 bail:
748 spin_unlock_irqrestore(&hp->lock, flags);
749
750 if (read_total) {
751 /* Activity is occurring, so reset the polling backoff value to
752 a minimum for performance. */
753 timeout = MIN_TIMEOUT;
754
755 tty_flip_buffer_push(&hp->port);
756 }
757 tty_kref_put(tty);
758
759 return poll_mask;
760}
761
762int hvc_poll(struct hvc_struct *hp)
763{
764 return __hvc_poll(hp, false);
765}
766EXPORT_SYMBOL_GPL(hvc_poll);
767
768/**
769 * __hvc_resize() - Update terminal window size information.
770 * @hp: HVC console pointer
771 * @ws: Terminal window size structure
772 *
773 * Stores the specified window size information in the hvc structure of @hp.
774 * The function schedule the tty resize update.
775 *
776 * Locking: Locking free; the function MUST be called holding hp->lock
777 */
778void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
779{
780 hp->ws = ws;
781 schedule_work(&hp->tty_resize);
782}
783EXPORT_SYMBOL_GPL(__hvc_resize);
784
785/*
786 * This kthread is either polling or interrupt driven. This is determined by
787 * calling hvc_poll() who determines whether a console adapter support
788 * interrupts.
789 */
790static int khvcd(void *unused)
791{
792 int poll_mask;
793 struct hvc_struct *hp;
794
795 set_freezable();
796 do {
797 poll_mask = 0;
798 hvc_kicked = 0;
799 try_to_freeze();
800 wmb();
801 if (!cpus_are_in_xmon()) {
802 mutex_lock(&hvc_structs_mutex);
803 list_for_each_entry(hp, &hvc_structs, next) {
804 poll_mask |= __hvc_poll(hp, true);
805 cond_resched();
806 }
807 mutex_unlock(&hvc_structs_mutex);
808 } else
809 poll_mask |= HVC_POLL_READ;
810 if (hvc_kicked)
811 continue;
812 set_current_state(TASK_INTERRUPTIBLE);
813 if (!hvc_kicked) {
814 if (poll_mask == 0)
815 schedule();
816 else {
817 unsigned long j_timeout;
818
819 if (timeout < MAX_TIMEOUT)
820 timeout += (timeout >> 6) + 1;
821
822 /*
823 * We don't use msleep_interruptible otherwise
824 * "kick" will fail to wake us up
825 */
826 j_timeout = msecs_to_jiffies(timeout) + 1;
827 schedule_timeout_interruptible(j_timeout);
828 }
829 }
830 __set_current_state(TASK_RUNNING);
831 } while (!kthread_should_stop());
832
833 return 0;
834}
835
836static int hvc_tiocmget(struct tty_struct *tty)
837{
838 struct hvc_struct *hp = tty->driver_data;
839
840 if (!hp || !hp->ops->tiocmget)
841 return -EINVAL;
842 return hp->ops->tiocmget(hp);
843}
844
845static int hvc_tiocmset(struct tty_struct *tty,
846 unsigned int set, unsigned int clear)
847{
848 struct hvc_struct *hp = tty->driver_data;
849
850 if (!hp || !hp->ops->tiocmset)
851 return -EINVAL;
852 return hp->ops->tiocmset(hp, set, clear);
853}
854
855#ifdef CONFIG_CONSOLE_POLL
856static int hvc_poll_init(struct tty_driver *driver, int line, char *options)
857{
858 return 0;
859}
860
861static int hvc_poll_get_char(struct tty_driver *driver, int line)
862{
863 struct tty_struct *tty = driver->ttys[0];
864 struct hvc_struct *hp = tty->driver_data;
865 int n;
866 char ch;
867
868 n = hp->ops->get_chars(hp->vtermno, &ch, 1);
869
870 if (n <= 0)
871 return NO_POLL_CHAR;
872
873 return ch;
874}
875
876static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
877{
878 struct tty_struct *tty = driver->ttys[0];
879 struct hvc_struct *hp = tty->driver_data;
880 int n;
881
882 do {
883 n = hp->ops->put_chars(hp->vtermno, &ch, 1);
884 } while (n <= 0);
885}
886#endif
887
888static const struct tty_operations hvc_ops = {
889 .install = hvc_install,
890 .open = hvc_open,
891 .close = hvc_close,
892 .cleanup = hvc_cleanup,
893 .write = hvc_write,
894 .hangup = hvc_hangup,
895 .unthrottle = hvc_unthrottle,
896 .write_room = hvc_write_room,
897 .chars_in_buffer = hvc_chars_in_buffer,
898 .tiocmget = hvc_tiocmget,
899 .tiocmset = hvc_tiocmset,
900#ifdef CONFIG_CONSOLE_POLL
901 .poll_init = hvc_poll_init,
902 .poll_get_char = hvc_poll_get_char,
903 .poll_put_char = hvc_poll_put_char,
904#endif
905};
906
907static const struct tty_port_operations hvc_port_ops = {
908 .destruct = hvc_port_destruct,
909};
910
911struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
912 const struct hv_ops *ops,
913 int outbuf_size)
914{
915 struct hvc_struct *hp;
916 int i;
917
918 /* We wait until a driver actually comes along */
919 if (atomic_inc_not_zero(&hvc_needs_init)) {
920 int err = hvc_init();
921 if (err)
922 return ERR_PTR(err);
923 }
924
925 hp = kzalloc(struct_size(hp, outbuf, outbuf_size), GFP_KERNEL);
926 if (!hp)
927 return ERR_PTR(-ENOMEM);
928
929 hp->vtermno = vtermno;
930 hp->data = data;
931 hp->ops = ops;
932 hp->outbuf_size = outbuf_size;
933
934 tty_port_init(&hp->port);
935 hp->port.ops = &hvc_port_ops;
936
937 INIT_WORK(&hp->tty_resize, hvc_set_winsz);
938 spin_lock_init(&hp->lock);
939 mutex_lock(&hvc_structs_mutex);
940
941 /*
942 * find index to use:
943 * see if this vterm id matches one registered for console.
944 */
945 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
946 if (vtermnos[i] == hp->vtermno &&
947 cons_ops[i] == hp->ops)
948 break;
949
950 if (i >= MAX_NR_HVC_CONSOLES) {
951
952 /* find 'empty' slot for console */
953 for (i = 0; i < MAX_NR_HVC_CONSOLES && vtermnos[i] != -1; i++) {
954 }
955
956 /* no matching slot, just use a counter */
957 if (i == MAX_NR_HVC_CONSOLES)
958 i = ++last_hvc + MAX_NR_HVC_CONSOLES;
959 }
960
961 hp->index = i;
962 if (i < MAX_NR_HVC_CONSOLES) {
963 cons_ops[i] = ops;
964 vtermnos[i] = vtermno;
965 }
966
967 list_add_tail(&(hp->next), &hvc_structs);
968 mutex_unlock(&hvc_structs_mutex);
969
970 /* check if we need to re-register the kernel console */
971 hvc_check_console(i);
972
973 return hp;
974}
975EXPORT_SYMBOL_GPL(hvc_alloc);
976
977void hvc_remove(struct hvc_struct *hp)
978{
979 unsigned long flags;
980 struct tty_struct *tty;
981
982 tty = tty_port_tty_get(&hp->port);
983
984 console_lock();
985 spin_lock_irqsave(&hp->lock, flags);
986 if (hp->index < MAX_NR_HVC_CONSOLES) {
987 vtermnos[hp->index] = -1;
988 cons_ops[hp->index] = NULL;
989 }
990
991 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
992
993 spin_unlock_irqrestore(&hp->lock, flags);
994 console_unlock();
995
996 /*
997 * We 'put' the instance that was grabbed when the kref instance
998 * was initialized using kref_init(). Let the last holder of this
999 * kref cause it to be removed, which will probably be the tty_vhangup
1000 * below.
1001 */
1002 tty_port_put(&hp->port);
1003
1004 /*
1005 * This function call will auto chain call hvc_hangup.
1006 */
1007 if (tty) {
1008 tty_vhangup(tty);
1009 tty_kref_put(tty);
1010 }
1011}
1012EXPORT_SYMBOL_GPL(hvc_remove);
1013
1014/* Driver initialization: called as soon as someone uses hvc_alloc(). */
1015static int hvc_init(void)
1016{
1017 struct tty_driver *drv;
1018 int err;
1019
1020 /* We need more than hvc_count adapters due to hotplug additions. */
1021 drv = tty_alloc_driver(HVC_ALLOC_TTY_ADAPTERS, TTY_DRIVER_REAL_RAW |
1022 TTY_DRIVER_RESET_TERMIOS);
1023 if (IS_ERR(drv)) {
1024 err = PTR_ERR(drv);
1025 goto out;
1026 }
1027
1028 drv->driver_name = "hvc";
1029 drv->name = "hvc";
1030 drv->major = HVC_MAJOR;
1031 drv->minor_start = HVC_MINOR;
1032 drv->type = TTY_DRIVER_TYPE_SYSTEM;
1033 drv->init_termios = tty_std_termios;
1034 tty_set_operations(drv, &hvc_ops);
1035
1036 /* Always start the kthread because there can be hotplug vty adapters
1037 * added later. */
1038 hvc_task = kthread_run(khvcd, NULL, "khvcd");
1039 if (IS_ERR(hvc_task)) {
1040 printk(KERN_ERR "Couldn't create kthread for console.\n");
1041 err = PTR_ERR(hvc_task);
1042 goto put_tty;
1043 }
1044
1045 err = tty_register_driver(drv);
1046 if (err) {
1047 printk(KERN_ERR "Couldn't register hvc console driver\n");
1048 goto stop_thread;
1049 }
1050
1051 /*
1052 * Make sure tty is fully registered before allowing it to be
1053 * found by hvc_console_device.
1054 */
1055 smp_mb();
1056 hvc_driver = drv;
1057 return 0;
1058
1059stop_thread:
1060 kthread_stop(hvc_task);
1061 hvc_task = NULL;
1062put_tty:
1063 tty_driver_kref_put(drv);
1064out:
1065 return err;
1066}