Loading...
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_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 enabled, bail out */
268 if (hvc_console.flags & CON_ENABLED)
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, 1);
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, 0);
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 int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
500{
501 struct hvc_struct *hp = tty->driver_data;
502 unsigned long flags;
503 int 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(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
926 GFP_KERNEL);
927 if (!hp)
928 return ERR_PTR(-ENOMEM);
929
930 hp->vtermno = vtermno;
931 hp->data = data;
932 hp->ops = ops;
933 hp->outbuf_size = outbuf_size;
934 hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
935
936 tty_port_init(&hp->port);
937 hp->port.ops = &hvc_port_ops;
938
939 INIT_WORK(&hp->tty_resize, hvc_set_winsz);
940 spin_lock_init(&hp->lock);
941 mutex_lock(&hvc_structs_mutex);
942
943 /*
944 * find index to use:
945 * see if this vterm id matches one registered for console.
946 */
947 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
948 if (vtermnos[i] == hp->vtermno &&
949 cons_ops[i] == hp->ops)
950 break;
951
952 if (i >= MAX_NR_HVC_CONSOLES) {
953
954 /* find 'empty' slot for console */
955 for (i = 0; i < MAX_NR_HVC_CONSOLES && vtermnos[i] != -1; i++) {
956 }
957
958 /* no matching slot, just use a counter */
959 if (i == MAX_NR_HVC_CONSOLES)
960 i = ++last_hvc + MAX_NR_HVC_CONSOLES;
961 }
962
963 hp->index = i;
964 if (i < MAX_NR_HVC_CONSOLES) {
965 cons_ops[i] = ops;
966 vtermnos[i] = vtermno;
967 }
968
969 list_add_tail(&(hp->next), &hvc_structs);
970 mutex_unlock(&hvc_structs_mutex);
971
972 /* check if we need to re-register the kernel console */
973 hvc_check_console(i);
974
975 return hp;
976}
977EXPORT_SYMBOL_GPL(hvc_alloc);
978
979int hvc_remove(struct hvc_struct *hp)
980{
981 unsigned long flags;
982 struct tty_struct *tty;
983
984 tty = tty_port_tty_get(&hp->port);
985
986 console_lock();
987 spin_lock_irqsave(&hp->lock, flags);
988 if (hp->index < MAX_NR_HVC_CONSOLES) {
989 vtermnos[hp->index] = -1;
990 cons_ops[hp->index] = NULL;
991 }
992
993 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
994
995 spin_unlock_irqrestore(&hp->lock, flags);
996 console_unlock();
997
998 /*
999 * We 'put' the instance that was grabbed when the kref instance
1000 * was initialized using kref_init(). Let the last holder of this
1001 * kref cause it to be removed, which will probably be the tty_vhangup
1002 * below.
1003 */
1004 tty_port_put(&hp->port);
1005
1006 /*
1007 * This function call will auto chain call hvc_hangup.
1008 */
1009 if (tty) {
1010 tty_vhangup(tty);
1011 tty_kref_put(tty);
1012 }
1013 return 0;
1014}
1015EXPORT_SYMBOL_GPL(hvc_remove);
1016
1017/* Driver initialization: called as soon as someone uses hvc_alloc(). */
1018static int hvc_init(void)
1019{
1020 struct tty_driver *drv;
1021 int err;
1022
1023 /* We need more than hvc_count adapters due to hotplug additions. */
1024 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
1025 if (!drv) {
1026 err = -ENOMEM;
1027 goto out;
1028 }
1029
1030 drv->driver_name = "hvc";
1031 drv->name = "hvc";
1032 drv->major = HVC_MAJOR;
1033 drv->minor_start = HVC_MINOR;
1034 drv->type = TTY_DRIVER_TYPE_SYSTEM;
1035 drv->init_termios = tty_std_termios;
1036 drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
1037 tty_set_operations(drv, &hvc_ops);
1038
1039 /* Always start the kthread because there can be hotplug vty adapters
1040 * added later. */
1041 hvc_task = kthread_run(khvcd, NULL, "khvcd");
1042 if (IS_ERR(hvc_task)) {
1043 printk(KERN_ERR "Couldn't create kthread for console.\n");
1044 err = PTR_ERR(hvc_task);
1045 goto put_tty;
1046 }
1047
1048 err = tty_register_driver(drv);
1049 if (err) {
1050 printk(KERN_ERR "Couldn't register hvc console driver\n");
1051 goto stop_thread;
1052 }
1053
1054 /*
1055 * Make sure tty is fully registered before allowing it to be
1056 * found by hvc_console_device.
1057 */
1058 smp_mb();
1059 hvc_driver = drv;
1060 return 0;
1061
1062stop_thread:
1063 kthread_stop(hvc_task);
1064 hvc_task = NULL;
1065put_tty:
1066 put_tty_driver(drv);
1067out:
1068 return err;
1069}
1/*
2 * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
3 * Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM
4 * Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
5 * Copyright (C) 2004 IBM Corporation
6 *
7 * Additional Author(s):
8 * Ryan S. Arnold <rsa@us.ibm.com>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 */
24
25#include <linux/console.h>
26#include <linux/cpumask.h>
27#include <linux/init.h>
28#include <linux/kbd_kern.h>
29#include <linux/kernel.h>
30#include <linux/kthread.h>
31#include <linux/list.h>
32#include <linux/module.h>
33#include <linux/major.h>
34#include <linux/atomic.h>
35#include <linux/sysrq.h>
36#include <linux/tty.h>
37#include <linux/tty_flip.h>
38#include <linux/sched.h>
39#include <linux/spinlock.h>
40#include <linux/delay.h>
41#include <linux/freezer.h>
42#include <linux/slab.h>
43#include <linux/serial_core.h>
44
45#include <asm/uaccess.h>
46
47#include "hvc_console.h"
48
49#define HVC_MAJOR 229
50#define HVC_MINOR 0
51
52/*
53 * Wait this long per iteration while trying to push buffered data to the
54 * hypervisor before allowing the tty to complete a close operation.
55 */
56#define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
57
58/*
59 * These sizes are most efficient for vio, because they are the
60 * native transfer size. We could make them selectable in the
61 * future to better deal with backends that want other buffer sizes.
62 */
63#define N_OUTBUF 16
64#define N_INBUF 16
65
66#define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
67
68static struct tty_driver *hvc_driver;
69static struct task_struct *hvc_task;
70
71/* Picks up late kicks after list walk but before schedule() */
72static int hvc_kicked;
73
74/* hvc_init is triggered from hvc_alloc, i.e. only when actually used */
75static atomic_t hvc_needs_init __read_mostly = ATOMIC_INIT(-1);
76
77static int hvc_init(void);
78
79#ifdef CONFIG_MAGIC_SYSRQ
80static int sysrq_pressed;
81#endif
82
83/* dynamic list of hvc_struct instances */
84static LIST_HEAD(hvc_structs);
85
86/*
87 * Protect the list of hvc_struct instances from inserts and removals during
88 * list traversal.
89 */
90static DEFINE_SPINLOCK(hvc_structs_lock);
91
92/*
93 * This value is used to assign a tty->index value to a hvc_struct based
94 * upon order of exposure via hvc_probe(), when we can not match it to
95 * a console candidate registered with hvc_instantiate().
96 */
97static int last_hvc = -1;
98
99/*
100 * Do not call this function with either the hvc_structs_lock or the hvc_struct
101 * lock held. If successful, this function increments the kref reference
102 * count against the target hvc_struct so it should be released when finished.
103 */
104static struct hvc_struct *hvc_get_by_index(int index)
105{
106 struct hvc_struct *hp;
107 unsigned long flags;
108
109 spin_lock(&hvc_structs_lock);
110
111 list_for_each_entry(hp, &hvc_structs, next) {
112 spin_lock_irqsave(&hp->lock, flags);
113 if (hp->index == index) {
114 tty_port_get(&hp->port);
115 spin_unlock_irqrestore(&hp->lock, flags);
116 spin_unlock(&hvc_structs_lock);
117 return hp;
118 }
119 spin_unlock_irqrestore(&hp->lock, flags);
120 }
121 hp = NULL;
122
123 spin_unlock(&hvc_structs_lock);
124 return hp;
125}
126
127
128/*
129 * Initial console vtermnos for console API usage prior to full console
130 * initialization. Any vty adapter outside this range will not have usable
131 * console interfaces but can still be used as a tty device. This has to be
132 * static because kmalloc will not work during early console init.
133 */
134static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
135static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
136 {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
137
138/*
139 * Console APIs, NOT TTY. These APIs are available immediately when
140 * hvc_console_setup() finds adapters.
141 */
142
143static void hvc_console_print(struct console *co, const char *b,
144 unsigned count)
145{
146 char c[N_OUTBUF] __ALIGNED__;
147 unsigned i = 0, n = 0;
148 int r, donecr = 0, index = co->index;
149
150 /* Console access attempt outside of acceptable console range. */
151 if (index >= MAX_NR_HVC_CONSOLES)
152 return;
153
154 /* This console adapter was removed so it is not usable. */
155 if (vtermnos[index] == -1)
156 return;
157
158 while (count > 0 || i > 0) {
159 if (count > 0 && i < sizeof(c)) {
160 if (b[n] == '\n' && !donecr) {
161 c[i++] = '\r';
162 donecr = 1;
163 } else {
164 c[i++] = b[n++];
165 donecr = 0;
166 --count;
167 }
168 } else {
169 r = cons_ops[index]->put_chars(vtermnos[index], c, i);
170 if (r <= 0) {
171 /* throw away characters on error
172 * but spin in case of -EAGAIN */
173 if (r != -EAGAIN)
174 i = 0;
175 } else if (r > 0) {
176 i -= r;
177 if (i > 0)
178 memmove(c, c+r, i);
179 }
180 }
181 }
182}
183
184static struct tty_driver *hvc_console_device(struct console *c, int *index)
185{
186 if (vtermnos[c->index] == -1)
187 return NULL;
188
189 *index = c->index;
190 return hvc_driver;
191}
192
193static int hvc_console_setup(struct console *co, char *options)
194{
195 if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
196 return -ENODEV;
197
198 if (vtermnos[co->index] == -1)
199 return -ENODEV;
200
201 return 0;
202}
203
204static struct console hvc_console = {
205 .name = "hvc",
206 .write = hvc_console_print,
207 .device = hvc_console_device,
208 .setup = hvc_console_setup,
209 .flags = CON_PRINTBUFFER,
210 .index = -1,
211};
212
213/*
214 * Early console initialization. Precedes driver initialization.
215 *
216 * (1) we are first, and the user specified another driver
217 * -- index will remain -1
218 * (2) we are first and the user specified no driver
219 * -- index will be set to 0, then we will fail setup.
220 * (3) we are first and the user specified our driver
221 * -- index will be set to user specified driver, and we will fail
222 * (4) we are after driver, and this initcall will register us
223 * -- if the user didn't specify a driver then the console will match
224 *
225 * Note that for cases 2 and 3, we will match later when the io driver
226 * calls hvc_instantiate() and call register again.
227 */
228static int __init hvc_console_init(void)
229{
230 register_console(&hvc_console);
231 return 0;
232}
233console_initcall(hvc_console_init);
234
235/* callback when the kboject ref count reaches zero. */
236static void hvc_port_destruct(struct tty_port *port)
237{
238 struct hvc_struct *hp = container_of(port, struct hvc_struct, port);
239 unsigned long flags;
240
241 spin_lock(&hvc_structs_lock);
242
243 spin_lock_irqsave(&hp->lock, flags);
244 list_del(&(hp->next));
245 spin_unlock_irqrestore(&hp->lock, flags);
246
247 spin_unlock(&hvc_structs_lock);
248
249 kfree(hp);
250}
251
252static void hvc_check_console(int index)
253{
254 /* Already enabled, bail out */
255 if (hvc_console.flags & CON_ENABLED)
256 return;
257
258 /* If this index is what the user requested, then register
259 * now (setup won't fail at this point). It's ok to just
260 * call register again if previously .setup failed.
261 */
262 if (index == hvc_console.index)
263 register_console(&hvc_console);
264}
265
266/*
267 * hvc_instantiate() is an early console discovery method which locates
268 * consoles * prior to the vio subsystem discovering them. Hotplugged
269 * vty adapters do NOT get an hvc_instantiate() callback since they
270 * appear after early console init.
271 */
272int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
273{
274 struct hvc_struct *hp;
275
276 if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
277 return -1;
278
279 if (vtermnos[index] != -1)
280 return -1;
281
282 /* make sure no no tty has been registered in this index */
283 hp = hvc_get_by_index(index);
284 if (hp) {
285 tty_port_put(&hp->port);
286 return -1;
287 }
288
289 vtermnos[index] = vtermno;
290 cons_ops[index] = ops;
291
292 /* reserve all indices up to and including this index */
293 if (last_hvc < index)
294 last_hvc = index;
295
296 /* check if we need to re-register the kernel console */
297 hvc_check_console(index);
298
299 return 0;
300}
301EXPORT_SYMBOL_GPL(hvc_instantiate);
302
303/* Wake the sleeping khvcd */
304void hvc_kick(void)
305{
306 hvc_kicked = 1;
307 wake_up_process(hvc_task);
308}
309EXPORT_SYMBOL_GPL(hvc_kick);
310
311static void hvc_unthrottle(struct tty_struct *tty)
312{
313 hvc_kick();
314}
315
316static int hvc_install(struct tty_driver *driver, struct tty_struct *tty)
317{
318 struct hvc_struct *hp;
319 int rc;
320
321 /* Auto increments kref reference if found. */
322 if (!(hp = hvc_get_by_index(tty->index)))
323 return -ENODEV;
324
325 tty->driver_data = hp;
326
327 rc = tty_port_install(&hp->port, driver, tty);
328 if (rc)
329 tty_port_put(&hp->port);
330 return rc;
331}
332
333/*
334 * The TTY interface won't be used until after the vio layer has exposed the vty
335 * adapter to the kernel.
336 */
337static int hvc_open(struct tty_struct *tty, struct file * filp)
338{
339 struct hvc_struct *hp = tty->driver_data;
340 unsigned long flags;
341 int rc = 0;
342
343 spin_lock_irqsave(&hp->port.lock, flags);
344 /* Check and then increment for fast path open. */
345 if (hp->port.count++ > 0) {
346 spin_unlock_irqrestore(&hp->port.lock, flags);
347 hvc_kick();
348 return 0;
349 } /* else count == 0 */
350 spin_unlock_irqrestore(&hp->port.lock, flags);
351
352 tty_port_tty_set(&hp->port, tty);
353
354 if (hp->ops->notifier_add)
355 rc = hp->ops->notifier_add(hp, hp->data);
356
357 /*
358 * If the notifier fails we return an error. The tty layer
359 * will call hvc_close() after a failed open but we don't want to clean
360 * up there so we'll clean up here and clear out the previously set
361 * tty fields and return the kref reference.
362 */
363 if (rc) {
364 tty_port_tty_set(&hp->port, NULL);
365 tty->driver_data = NULL;
366 tty_port_put(&hp->port);
367 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
368 } else
369 /* We are ready... raise DTR/RTS */
370 if (C_BAUD(tty))
371 if (hp->ops->dtr_rts)
372 hp->ops->dtr_rts(hp, 1);
373
374 /* Force wakeup of the polling thread */
375 hvc_kick();
376
377 return rc;
378}
379
380static void hvc_close(struct tty_struct *tty, struct file * filp)
381{
382 struct hvc_struct *hp;
383 unsigned long flags;
384
385 if (tty_hung_up_p(filp))
386 return;
387
388 /*
389 * No driver_data means that this close was issued after a failed
390 * hvc_open by the tty layer's release_dev() function and we can just
391 * exit cleanly because the kref reference wasn't made.
392 */
393 if (!tty->driver_data)
394 return;
395
396 hp = tty->driver_data;
397
398 spin_lock_irqsave(&hp->port.lock, flags);
399
400 if (--hp->port.count == 0) {
401 spin_unlock_irqrestore(&hp->port.lock, flags);
402 /* We are done with the tty pointer now. */
403 tty_port_tty_set(&hp->port, NULL);
404
405 if (C_HUPCL(tty))
406 if (hp->ops->dtr_rts)
407 hp->ops->dtr_rts(hp, 0);
408
409 if (hp->ops->notifier_del)
410 hp->ops->notifier_del(hp, hp->data);
411
412 /* cancel pending tty resize work */
413 cancel_work_sync(&hp->tty_resize);
414
415 /*
416 * Chain calls chars_in_buffer() and returns immediately if
417 * there is no buffered data otherwise sleeps on a wait queue
418 * waking periodically to check chars_in_buffer().
419 */
420 tty_wait_until_sent_from_close(tty, HVC_CLOSE_WAIT);
421 } else {
422 if (hp->port.count < 0)
423 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
424 hp->vtermno, hp->port.count);
425 spin_unlock_irqrestore(&hp->port.lock, flags);
426 }
427}
428
429static void hvc_cleanup(struct tty_struct *tty)
430{
431 struct hvc_struct *hp = tty->driver_data;
432
433 tty_port_put(&hp->port);
434}
435
436static void hvc_hangup(struct tty_struct *tty)
437{
438 struct hvc_struct *hp = tty->driver_data;
439 unsigned long flags;
440
441 if (!hp)
442 return;
443
444 /* cancel pending tty resize work */
445 cancel_work_sync(&hp->tty_resize);
446
447 spin_lock_irqsave(&hp->port.lock, flags);
448
449 /*
450 * The N_TTY line discipline has problems such that in a close vs
451 * open->hangup case this can be called after the final close so prevent
452 * that from happening for now.
453 */
454 if (hp->port.count <= 0) {
455 spin_unlock_irqrestore(&hp->port.lock, flags);
456 return;
457 }
458
459 hp->port.count = 0;
460 spin_unlock_irqrestore(&hp->port.lock, flags);
461 tty_port_tty_set(&hp->port, NULL);
462
463 hp->n_outbuf = 0;
464
465 if (hp->ops->notifier_hangup)
466 hp->ops->notifier_hangup(hp, hp->data);
467}
468
469/*
470 * Push buffered characters whether they were just recently buffered or waiting
471 * on a blocked hypervisor. Call this function with hp->lock held.
472 */
473static int hvc_push(struct hvc_struct *hp)
474{
475 int n;
476
477 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
478 if (n <= 0) {
479 if (n == 0 || n == -EAGAIN) {
480 hp->do_wakeup = 1;
481 return 0;
482 }
483 /* throw away output on error; this happens when
484 there is no session connected to the vterm. */
485 hp->n_outbuf = 0;
486 } else
487 hp->n_outbuf -= n;
488 if (hp->n_outbuf > 0)
489 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
490 else
491 hp->do_wakeup = 1;
492
493 return n;
494}
495
496static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
497{
498 struct hvc_struct *hp = tty->driver_data;
499 unsigned long flags;
500 int rsize, written = 0;
501
502 /* This write was probably executed during a tty close. */
503 if (!hp)
504 return -EPIPE;
505
506 /* FIXME what's this (unprotected) check for? */
507 if (hp->port.count <= 0)
508 return -EIO;
509
510 spin_lock_irqsave(&hp->lock, flags);
511
512 /* Push pending writes */
513 if (hp->n_outbuf > 0)
514 hvc_push(hp);
515
516 while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
517 if (rsize > count)
518 rsize = count;
519 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
520 count -= rsize;
521 buf += rsize;
522 hp->n_outbuf += rsize;
523 written += rsize;
524 hvc_push(hp);
525 }
526 spin_unlock_irqrestore(&hp->lock, flags);
527
528 /*
529 * Racy, but harmless, kick thread if there is still pending data.
530 */
531 if (hp->n_outbuf)
532 hvc_kick();
533
534 return written;
535}
536
537/**
538 * hvc_set_winsz() - Resize the hvc tty terminal window.
539 * @work: work structure.
540 *
541 * The routine shall not be called within an atomic context because it
542 * might sleep.
543 *
544 * Locking: hp->lock
545 */
546static void hvc_set_winsz(struct work_struct *work)
547{
548 struct hvc_struct *hp;
549 unsigned long hvc_flags;
550 struct tty_struct *tty;
551 struct winsize ws;
552
553 hp = container_of(work, struct hvc_struct, tty_resize);
554
555 tty = tty_port_tty_get(&hp->port);
556 if (!tty)
557 return;
558
559 spin_lock_irqsave(&hp->lock, hvc_flags);
560 ws = hp->ws;
561 spin_unlock_irqrestore(&hp->lock, hvc_flags);
562
563 tty_do_resize(tty, &ws);
564 tty_kref_put(tty);
565}
566
567/*
568 * This is actually a contract between the driver and the tty layer outlining
569 * how much write room the driver can guarantee will be sent OR BUFFERED. This
570 * driver MUST honor the return value.
571 */
572static int hvc_write_room(struct tty_struct *tty)
573{
574 struct hvc_struct *hp = tty->driver_data;
575
576 if (!hp)
577 return 0;
578
579 return hp->outbuf_size - hp->n_outbuf;
580}
581
582static int hvc_chars_in_buffer(struct tty_struct *tty)
583{
584 struct hvc_struct *hp = tty->driver_data;
585
586 if (!hp)
587 return 0;
588 return hp->n_outbuf;
589}
590
591/*
592 * timeout will vary between the MIN and MAX values defined here. By default
593 * and during console activity we will use a default MIN_TIMEOUT of 10. When
594 * the console is idle, we increase the timeout value on each pass through
595 * msleep until we reach the max. This may be noticeable as a brief (average
596 * one second) delay on the console before the console responds to input when
597 * there has been no input for some time.
598 */
599#define MIN_TIMEOUT (10)
600#define MAX_TIMEOUT (2000)
601static u32 timeout = MIN_TIMEOUT;
602
603#define HVC_POLL_READ 0x00000001
604#define HVC_POLL_WRITE 0x00000002
605
606int hvc_poll(struct hvc_struct *hp)
607{
608 struct tty_struct *tty;
609 int i, n, poll_mask = 0;
610 char buf[N_INBUF] __ALIGNED__;
611 unsigned long flags;
612 int read_total = 0;
613 int written_total = 0;
614
615 spin_lock_irqsave(&hp->lock, flags);
616
617 /* Push pending writes */
618 if (hp->n_outbuf > 0)
619 written_total = hvc_push(hp);
620
621 /* Reschedule us if still some write pending */
622 if (hp->n_outbuf > 0) {
623 poll_mask |= HVC_POLL_WRITE;
624 /* If hvc_push() was not able to write, sleep a few msecs */
625 timeout = (written_total) ? 0 : MIN_TIMEOUT;
626 }
627
628 /* No tty attached, just skip */
629 tty = tty_port_tty_get(&hp->port);
630 if (tty == NULL)
631 goto bail;
632
633 /* Now check if we can get data (are we throttled ?) */
634 if (test_bit(TTY_THROTTLED, &tty->flags))
635 goto throttled;
636
637 /* If we aren't notifier driven and aren't throttled, we always
638 * request a reschedule
639 */
640 if (!hp->irq_requested)
641 poll_mask |= HVC_POLL_READ;
642
643 /* Read data if any */
644 for (;;) {
645 int count = tty_buffer_request_room(&hp->port, N_INBUF);
646
647 /* If flip is full, just reschedule a later read */
648 if (count == 0) {
649 poll_mask |= HVC_POLL_READ;
650 break;
651 }
652
653 n = hp->ops->get_chars(hp->vtermno, buf, count);
654 if (n <= 0) {
655 /* Hangup the tty when disconnected from host */
656 if (n == -EPIPE) {
657 spin_unlock_irqrestore(&hp->lock, flags);
658 tty_hangup(tty);
659 spin_lock_irqsave(&hp->lock, flags);
660 } else if ( n == -EAGAIN ) {
661 /*
662 * Some back-ends can only ensure a certain min
663 * num of bytes read, which may be > 'count'.
664 * Let the tty clear the flip buff to make room.
665 */
666 poll_mask |= HVC_POLL_READ;
667 }
668 break;
669 }
670 for (i = 0; i < n; ++i) {
671#ifdef CONFIG_MAGIC_SYSRQ
672 if (hp->index == hvc_console.index) {
673 /* Handle the SysRq Hack */
674 /* XXX should support a sequence */
675 if (buf[i] == '\x0f') { /* ^O */
676 /* if ^O is pressed again, reset
677 * sysrq_pressed and flip ^O char */
678 sysrq_pressed = !sysrq_pressed;
679 if (sysrq_pressed)
680 continue;
681 } else if (sysrq_pressed) {
682 handle_sysrq(buf[i]);
683 sysrq_pressed = 0;
684 continue;
685 }
686 }
687#endif /* CONFIG_MAGIC_SYSRQ */
688 tty_insert_flip_char(&hp->port, buf[i], 0);
689 }
690
691 read_total += n;
692 }
693 throttled:
694 /* Wakeup write queue if necessary */
695 if (hp->do_wakeup) {
696 hp->do_wakeup = 0;
697 tty_wakeup(tty);
698 }
699 bail:
700 spin_unlock_irqrestore(&hp->lock, flags);
701
702 if (read_total) {
703 /* Activity is occurring, so reset the polling backoff value to
704 a minimum for performance. */
705 timeout = MIN_TIMEOUT;
706
707 tty_flip_buffer_push(&hp->port);
708 }
709 tty_kref_put(tty);
710
711 return poll_mask;
712}
713EXPORT_SYMBOL_GPL(hvc_poll);
714
715/**
716 * __hvc_resize() - Update terminal window size information.
717 * @hp: HVC console pointer
718 * @ws: Terminal window size structure
719 *
720 * Stores the specified window size information in the hvc structure of @hp.
721 * The function schedule the tty resize update.
722 *
723 * Locking: Locking free; the function MUST be called holding hp->lock
724 */
725void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
726{
727 hp->ws = ws;
728 schedule_work(&hp->tty_resize);
729}
730EXPORT_SYMBOL_GPL(__hvc_resize);
731
732/*
733 * This kthread is either polling or interrupt driven. This is determined by
734 * calling hvc_poll() who determines whether a console adapter support
735 * interrupts.
736 */
737static int khvcd(void *unused)
738{
739 int poll_mask;
740 struct hvc_struct *hp;
741
742 set_freezable();
743 do {
744 poll_mask = 0;
745 hvc_kicked = 0;
746 try_to_freeze();
747 wmb();
748 if (!cpus_are_in_xmon()) {
749 spin_lock(&hvc_structs_lock);
750 list_for_each_entry(hp, &hvc_structs, next) {
751 poll_mask |= hvc_poll(hp);
752 }
753 spin_unlock(&hvc_structs_lock);
754 } else
755 poll_mask |= HVC_POLL_READ;
756 if (hvc_kicked)
757 continue;
758 set_current_state(TASK_INTERRUPTIBLE);
759 if (!hvc_kicked) {
760 if (poll_mask == 0)
761 schedule();
762 else {
763 if (timeout < MAX_TIMEOUT)
764 timeout += (timeout >> 6) + 1;
765
766 msleep_interruptible(timeout);
767 }
768 }
769 __set_current_state(TASK_RUNNING);
770 } while (!kthread_should_stop());
771
772 return 0;
773}
774
775static int hvc_tiocmget(struct tty_struct *tty)
776{
777 struct hvc_struct *hp = tty->driver_data;
778
779 if (!hp || !hp->ops->tiocmget)
780 return -EINVAL;
781 return hp->ops->tiocmget(hp);
782}
783
784static int hvc_tiocmset(struct tty_struct *tty,
785 unsigned int set, unsigned int clear)
786{
787 struct hvc_struct *hp = tty->driver_data;
788
789 if (!hp || !hp->ops->tiocmset)
790 return -EINVAL;
791 return hp->ops->tiocmset(hp, set, clear);
792}
793
794#ifdef CONFIG_CONSOLE_POLL
795static int hvc_poll_init(struct tty_driver *driver, int line, char *options)
796{
797 return 0;
798}
799
800static int hvc_poll_get_char(struct tty_driver *driver, int line)
801{
802 struct tty_struct *tty = driver->ttys[0];
803 struct hvc_struct *hp = tty->driver_data;
804 int n;
805 char ch;
806
807 n = hp->ops->get_chars(hp->vtermno, &ch, 1);
808
809 if (n == 0)
810 return NO_POLL_CHAR;
811
812 return ch;
813}
814
815static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
816{
817 struct tty_struct *tty = driver->ttys[0];
818 struct hvc_struct *hp = tty->driver_data;
819 int n;
820
821 do {
822 n = hp->ops->put_chars(hp->vtermno, &ch, 1);
823 } while (n <= 0);
824}
825#endif
826
827static const struct tty_operations hvc_ops = {
828 .install = hvc_install,
829 .open = hvc_open,
830 .close = hvc_close,
831 .cleanup = hvc_cleanup,
832 .write = hvc_write,
833 .hangup = hvc_hangup,
834 .unthrottle = hvc_unthrottle,
835 .write_room = hvc_write_room,
836 .chars_in_buffer = hvc_chars_in_buffer,
837 .tiocmget = hvc_tiocmget,
838 .tiocmset = hvc_tiocmset,
839#ifdef CONFIG_CONSOLE_POLL
840 .poll_init = hvc_poll_init,
841 .poll_get_char = hvc_poll_get_char,
842 .poll_put_char = hvc_poll_put_char,
843#endif
844};
845
846static const struct tty_port_operations hvc_port_ops = {
847 .destruct = hvc_port_destruct,
848};
849
850struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
851 const struct hv_ops *ops,
852 int outbuf_size)
853{
854 struct hvc_struct *hp;
855 int i;
856
857 /* We wait until a driver actually comes along */
858 if (atomic_inc_not_zero(&hvc_needs_init)) {
859 int err = hvc_init();
860 if (err)
861 return ERR_PTR(err);
862 }
863
864 hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
865 GFP_KERNEL);
866 if (!hp)
867 return ERR_PTR(-ENOMEM);
868
869 hp->vtermno = vtermno;
870 hp->data = data;
871 hp->ops = ops;
872 hp->outbuf_size = outbuf_size;
873 hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
874
875 tty_port_init(&hp->port);
876 hp->port.ops = &hvc_port_ops;
877
878 INIT_WORK(&hp->tty_resize, hvc_set_winsz);
879 spin_lock_init(&hp->lock);
880 spin_lock(&hvc_structs_lock);
881
882 /*
883 * find index to use:
884 * see if this vterm id matches one registered for console.
885 */
886 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
887 if (vtermnos[i] == hp->vtermno &&
888 cons_ops[i] == hp->ops)
889 break;
890
891 /* no matching slot, just use a counter */
892 if (i >= MAX_NR_HVC_CONSOLES)
893 i = ++last_hvc;
894
895 hp->index = i;
896 cons_ops[i] = ops;
897 vtermnos[i] = vtermno;
898
899 list_add_tail(&(hp->next), &hvc_structs);
900 spin_unlock(&hvc_structs_lock);
901
902 /* check if we need to re-register the kernel console */
903 hvc_check_console(i);
904
905 return hp;
906}
907EXPORT_SYMBOL_GPL(hvc_alloc);
908
909int hvc_remove(struct hvc_struct *hp)
910{
911 unsigned long flags;
912 struct tty_struct *tty;
913
914 tty = tty_port_tty_get(&hp->port);
915
916 spin_lock_irqsave(&hp->lock, flags);
917 if (hp->index < MAX_NR_HVC_CONSOLES) {
918 console_lock();
919 vtermnos[hp->index] = -1;
920 cons_ops[hp->index] = NULL;
921 console_unlock();
922 }
923
924 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
925
926 spin_unlock_irqrestore(&hp->lock, flags);
927
928 /*
929 * We 'put' the instance that was grabbed when the kref instance
930 * was initialized using kref_init(). Let the last holder of this
931 * kref cause it to be removed, which will probably be the tty_vhangup
932 * below.
933 */
934 tty_port_put(&hp->port);
935
936 /*
937 * This function call will auto chain call hvc_hangup.
938 */
939 if (tty) {
940 tty_vhangup(tty);
941 tty_kref_put(tty);
942 }
943 return 0;
944}
945EXPORT_SYMBOL_GPL(hvc_remove);
946
947/* Driver initialization: called as soon as someone uses hvc_alloc(). */
948static int hvc_init(void)
949{
950 struct tty_driver *drv;
951 int err;
952
953 /* We need more than hvc_count adapters due to hotplug additions. */
954 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
955 if (!drv) {
956 err = -ENOMEM;
957 goto out;
958 }
959
960 drv->driver_name = "hvc";
961 drv->name = "hvc";
962 drv->major = HVC_MAJOR;
963 drv->minor_start = HVC_MINOR;
964 drv->type = TTY_DRIVER_TYPE_SYSTEM;
965 drv->init_termios = tty_std_termios;
966 drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
967 tty_set_operations(drv, &hvc_ops);
968
969 /* Always start the kthread because there can be hotplug vty adapters
970 * added later. */
971 hvc_task = kthread_run(khvcd, NULL, "khvcd");
972 if (IS_ERR(hvc_task)) {
973 printk(KERN_ERR "Couldn't create kthread for console.\n");
974 err = PTR_ERR(hvc_task);
975 goto put_tty;
976 }
977
978 err = tty_register_driver(drv);
979 if (err) {
980 printk(KERN_ERR "Couldn't register hvc console driver\n");
981 goto stop_thread;
982 }
983
984 /*
985 * Make sure tty is fully registered before allowing it to be
986 * found by hvc_console_device.
987 */
988 smp_mb();
989 hvc_driver = drv;
990 return 0;
991
992stop_thread:
993 kthread_stop(hvc_task);
994 hvc_task = NULL;
995put_tty:
996 put_tty_driver(drv);
997out:
998 return err;
999}
1000
1001/* This isn't particularly necessary due to this being a console driver
1002 * but it is nice to be thorough.
1003 */
1004static void __exit hvc_exit(void)
1005{
1006 if (hvc_driver) {
1007 kthread_stop(hvc_task);
1008
1009 tty_unregister_driver(hvc_driver);
1010 /* return tty_struct instances allocated in hvc_init(). */
1011 put_tty_driver(hvc_driver);
1012 unregister_console(&hvc_console);
1013 }
1014}
1015module_exit(hvc_exit);