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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 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 /* reserve all indices up to and including this index */
306 if (last_hvc < index)
307 last_hvc = index;
308
309 /* check if we need to re-register the kernel console */
310 hvc_check_console(index);
311
312 return 0;
313}
314EXPORT_SYMBOL_GPL(hvc_instantiate);
315
316/* Wake the sleeping khvcd */
317void hvc_kick(void)
318{
319 hvc_kicked = 1;
320 wake_up_process(hvc_task);
321}
322EXPORT_SYMBOL_GPL(hvc_kick);
323
324static void hvc_unthrottle(struct tty_struct *tty)
325{
326 hvc_kick();
327}
328
329static int hvc_install(struct tty_driver *driver, struct tty_struct *tty)
330{
331 struct hvc_struct *hp;
332 int rc;
333
334 /* Auto increments kref reference if found. */
335 hp = hvc_get_by_index(tty->index);
336 if (!hp)
337 return -ENODEV;
338
339 tty->driver_data = hp;
340
341 rc = tty_port_install(&hp->port, driver, tty);
342 if (rc)
343 tty_port_put(&hp->port);
344 return rc;
345}
346
347/*
348 * The TTY interface won't be used until after the vio layer has exposed the vty
349 * adapter to the kernel.
350 */
351static int hvc_open(struct tty_struct *tty, struct file * filp)
352{
353 struct hvc_struct *hp = tty->driver_data;
354 unsigned long flags;
355 int rc = 0;
356
357 spin_lock_irqsave(&hp->port.lock, flags);
358 /* Check and then increment for fast path open. */
359 if (hp->port.count++ > 0) {
360 spin_unlock_irqrestore(&hp->port.lock, flags);
361 hvc_kick();
362 return 0;
363 } /* else count == 0 */
364 spin_unlock_irqrestore(&hp->port.lock, flags);
365
366 tty_port_tty_set(&hp->port, tty);
367
368 if (hp->ops->notifier_add)
369 rc = hp->ops->notifier_add(hp, hp->data);
370
371 /*
372 * If the notifier fails we return an error. The tty layer
373 * will call hvc_close() after a failed open but we don't want to clean
374 * up there so we'll clean up here and clear out the previously set
375 * tty fields and return the kref reference.
376 */
377 if (rc) {
378 tty_port_tty_set(&hp->port, NULL);
379 tty->driver_data = NULL;
380 tty_port_put(&hp->port);
381 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
382 } else
383 /* We are ready... raise DTR/RTS */
384 if (C_BAUD(tty))
385 if (hp->ops->dtr_rts)
386 hp->ops->dtr_rts(hp, 1);
387
388 /* Force wakeup of the polling thread */
389 hvc_kick();
390
391 return rc;
392}
393
394static void hvc_close(struct tty_struct *tty, struct file * filp)
395{
396 struct hvc_struct *hp;
397 unsigned long flags;
398
399 if (tty_hung_up_p(filp))
400 return;
401
402 /*
403 * No driver_data means that this close was issued after a failed
404 * hvc_open by the tty layer's release_dev() function and we can just
405 * exit cleanly because the kref reference wasn't made.
406 */
407 if (!tty->driver_data)
408 return;
409
410 hp = tty->driver_data;
411
412 spin_lock_irqsave(&hp->port.lock, flags);
413
414 if (--hp->port.count == 0) {
415 spin_unlock_irqrestore(&hp->port.lock, flags);
416 /* We are done with the tty pointer now. */
417 tty_port_tty_set(&hp->port, NULL);
418
419 if (C_HUPCL(tty))
420 if (hp->ops->dtr_rts)
421 hp->ops->dtr_rts(hp, 0);
422
423 if (hp->ops->notifier_del)
424 hp->ops->notifier_del(hp, hp->data);
425
426 /* cancel pending tty resize work */
427 cancel_work_sync(&hp->tty_resize);
428
429 /*
430 * Chain calls chars_in_buffer() and returns immediately if
431 * there is no buffered data otherwise sleeps on a wait queue
432 * waking periodically to check chars_in_buffer().
433 */
434 tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
435 } else {
436 if (hp->port.count < 0)
437 printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
438 hp->vtermno, hp->port.count);
439 spin_unlock_irqrestore(&hp->port.lock, flags);
440 }
441}
442
443static void hvc_cleanup(struct tty_struct *tty)
444{
445 struct hvc_struct *hp = tty->driver_data;
446
447 tty_port_put(&hp->port);
448}
449
450static void hvc_hangup(struct tty_struct *tty)
451{
452 struct hvc_struct *hp = tty->driver_data;
453 unsigned long flags;
454
455 if (!hp)
456 return;
457
458 /* cancel pending tty resize work */
459 cancel_work_sync(&hp->tty_resize);
460
461 spin_lock_irqsave(&hp->port.lock, flags);
462
463 /*
464 * The N_TTY line discipline has problems such that in a close vs
465 * open->hangup case this can be called after the final close so prevent
466 * that from happening for now.
467 */
468 if (hp->port.count <= 0) {
469 spin_unlock_irqrestore(&hp->port.lock, flags);
470 return;
471 }
472
473 hp->port.count = 0;
474 spin_unlock_irqrestore(&hp->port.lock, flags);
475 tty_port_tty_set(&hp->port, NULL);
476
477 hp->n_outbuf = 0;
478
479 if (hp->ops->notifier_hangup)
480 hp->ops->notifier_hangup(hp, hp->data);
481}
482
483/*
484 * Push buffered characters whether they were just recently buffered or waiting
485 * on a blocked hypervisor. Call this function with hp->lock held.
486 */
487static int hvc_push(struct hvc_struct *hp)
488{
489 int n;
490
491 n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
492 if (n <= 0) {
493 if (n == 0 || n == -EAGAIN) {
494 hp->do_wakeup = 1;
495 return 0;
496 }
497 /* throw away output on error; this happens when
498 there is no session connected to the vterm. */
499 hp->n_outbuf = 0;
500 } else
501 hp->n_outbuf -= n;
502 if (hp->n_outbuf > 0)
503 memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
504 else
505 hp->do_wakeup = 1;
506
507 return n;
508}
509
510static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
511{
512 struct hvc_struct *hp = tty->driver_data;
513 unsigned long flags;
514 int rsize, written = 0;
515
516 /* This write was probably executed during a tty close. */
517 if (!hp)
518 return -EPIPE;
519
520 /* FIXME what's this (unprotected) check for? */
521 if (hp->port.count <= 0)
522 return -EIO;
523
524 while (count > 0) {
525 int ret = 0;
526
527 spin_lock_irqsave(&hp->lock, flags);
528
529 rsize = hp->outbuf_size - hp->n_outbuf;
530
531 if (rsize) {
532 if (rsize > count)
533 rsize = count;
534 memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
535 count -= rsize;
536 buf += rsize;
537 hp->n_outbuf += rsize;
538 written += rsize;
539 }
540
541 if (hp->n_outbuf > 0)
542 ret = hvc_push(hp);
543
544 spin_unlock_irqrestore(&hp->lock, flags);
545
546 if (!ret)
547 break;
548
549 if (count) {
550 if (hp->n_outbuf > 0)
551 hvc_flush(hp);
552 cond_resched();
553 }
554 }
555
556 /*
557 * Racy, but harmless, kick thread if there is still pending data.
558 */
559 if (hp->n_outbuf)
560 hvc_kick();
561
562 return written;
563}
564
565/**
566 * hvc_set_winsz() - Resize the hvc tty terminal window.
567 * @work: work structure.
568 *
569 * The routine shall not be called within an atomic context because it
570 * might sleep.
571 *
572 * Locking: hp->lock
573 */
574static void hvc_set_winsz(struct work_struct *work)
575{
576 struct hvc_struct *hp;
577 unsigned long hvc_flags;
578 struct tty_struct *tty;
579 struct winsize ws;
580
581 hp = container_of(work, struct hvc_struct, tty_resize);
582
583 tty = tty_port_tty_get(&hp->port);
584 if (!tty)
585 return;
586
587 spin_lock_irqsave(&hp->lock, hvc_flags);
588 ws = hp->ws;
589 spin_unlock_irqrestore(&hp->lock, hvc_flags);
590
591 tty_do_resize(tty, &ws);
592 tty_kref_put(tty);
593}
594
595/*
596 * This is actually a contract between the driver and the tty layer outlining
597 * how much write room the driver can guarantee will be sent OR BUFFERED. This
598 * driver MUST honor the return value.
599 */
600static int hvc_write_room(struct tty_struct *tty)
601{
602 struct hvc_struct *hp = tty->driver_data;
603
604 if (!hp)
605 return 0;
606
607 return hp->outbuf_size - hp->n_outbuf;
608}
609
610static int hvc_chars_in_buffer(struct tty_struct *tty)
611{
612 struct hvc_struct *hp = tty->driver_data;
613
614 if (!hp)
615 return 0;
616 return hp->n_outbuf;
617}
618
619/*
620 * timeout will vary between the MIN and MAX values defined here. By default
621 * and during console activity we will use a default MIN_TIMEOUT of 10. When
622 * the console is idle, we increase the timeout value on each pass through
623 * msleep until we reach the max. This may be noticeable as a brief (average
624 * one second) delay on the console before the console responds to input when
625 * there has been no input for some time.
626 */
627#define MIN_TIMEOUT (10)
628#define MAX_TIMEOUT (2000)
629static u32 timeout = MIN_TIMEOUT;
630
631/*
632 * Maximum number of bytes to get from the console driver if hvc_poll is
633 * called from driver (and can't sleep). Any more than this and we break
634 * and start polling with khvcd. This value was derived from from an OpenBMC
635 * console with the OPAL driver that results in about 0.25ms interrupts off
636 * latency.
637 */
638#define HVC_ATOMIC_READ_MAX 128
639
640#define HVC_POLL_READ 0x00000001
641#define HVC_POLL_WRITE 0x00000002
642
643static int __hvc_poll(struct hvc_struct *hp, bool may_sleep)
644{
645 struct tty_struct *tty;
646 int i, n, count, poll_mask = 0;
647 char buf[N_INBUF] __ALIGNED__;
648 unsigned long flags;
649 int read_total = 0;
650 int written_total = 0;
651
652 spin_lock_irqsave(&hp->lock, flags);
653
654 /* Push pending writes */
655 if (hp->n_outbuf > 0)
656 written_total = hvc_push(hp);
657
658 /* Reschedule us if still some write pending */
659 if (hp->n_outbuf > 0) {
660 poll_mask |= HVC_POLL_WRITE;
661 /* If hvc_push() was not able to write, sleep a few msecs */
662 timeout = (written_total) ? 0 : MIN_TIMEOUT;
663 }
664
665 if (may_sleep) {
666 spin_unlock_irqrestore(&hp->lock, flags);
667 cond_resched();
668 spin_lock_irqsave(&hp->lock, flags);
669 }
670
671 /* No tty attached, just skip */
672 tty = tty_port_tty_get(&hp->port);
673 if (tty == NULL)
674 goto bail;
675
676 /* Now check if we can get data (are we throttled ?) */
677 if (tty_throttled(tty))
678 goto out;
679
680 /* If we aren't notifier driven and aren't throttled, we always
681 * request a reschedule
682 */
683 if (!hp->irq_requested)
684 poll_mask |= HVC_POLL_READ;
685
686 read_again:
687 /* Read data if any */
688 count = tty_buffer_request_room(&hp->port, N_INBUF);
689
690 /* If flip is full, just reschedule a later read */
691 if (count == 0) {
692 poll_mask |= HVC_POLL_READ;
693 goto out;
694 }
695
696 n = hp->ops->get_chars(hp->vtermno, buf, count);
697 if (n <= 0) {
698 /* Hangup the tty when disconnected from host */
699 if (n == -EPIPE) {
700 spin_unlock_irqrestore(&hp->lock, flags);
701 tty_hangup(tty);
702 spin_lock_irqsave(&hp->lock, flags);
703 } else if ( n == -EAGAIN ) {
704 /*
705 * Some back-ends can only ensure a certain min
706 * num of bytes read, which may be > 'count'.
707 * Let the tty clear the flip buff to make room.
708 */
709 poll_mask |= HVC_POLL_READ;
710 }
711 goto out;
712 }
713
714 for (i = 0; i < n; ++i) {
715#ifdef CONFIG_MAGIC_SYSRQ
716 if (hp->index == hvc_console.index) {
717 /* Handle the SysRq Hack */
718 /* XXX should support a sequence */
719 if (buf[i] == '\x0f') { /* ^O */
720 /* if ^O is pressed again, reset
721 * sysrq_pressed and flip ^O char */
722 sysrq_pressed = !sysrq_pressed;
723 if (sysrq_pressed)
724 continue;
725 } else if (sysrq_pressed) {
726 handle_sysrq(buf[i]);
727 sysrq_pressed = 0;
728 continue;
729 }
730 }
731#endif /* CONFIG_MAGIC_SYSRQ */
732 tty_insert_flip_char(&hp->port, buf[i], 0);
733 }
734 read_total += n;
735
736 if (may_sleep) {
737 /* Keep going until the flip is full */
738 spin_unlock_irqrestore(&hp->lock, flags);
739 cond_resched();
740 spin_lock_irqsave(&hp->lock, flags);
741 goto read_again;
742 } else if (read_total < HVC_ATOMIC_READ_MAX) {
743 /* Break and defer if it's a large read in atomic */
744 goto read_again;
745 }
746
747 /*
748 * Latency break, schedule another poll immediately.
749 */
750 poll_mask |= HVC_POLL_READ;
751
752 out:
753 /* Wakeup write queue if necessary */
754 if (hp->do_wakeup) {
755 hp->do_wakeup = 0;
756 tty_wakeup(tty);
757 }
758 bail:
759 spin_unlock_irqrestore(&hp->lock, flags);
760
761 if (read_total) {
762 /* Activity is occurring, so reset the polling backoff value to
763 a minimum for performance. */
764 timeout = MIN_TIMEOUT;
765
766 tty_flip_buffer_push(&hp->port);
767 }
768 tty_kref_put(tty);
769
770 return poll_mask;
771}
772
773int hvc_poll(struct hvc_struct *hp)
774{
775 return __hvc_poll(hp, false);
776}
777EXPORT_SYMBOL_GPL(hvc_poll);
778
779/**
780 * __hvc_resize() - Update terminal window size information.
781 * @hp: HVC console pointer
782 * @ws: Terminal window size structure
783 *
784 * Stores the specified window size information in the hvc structure of @hp.
785 * The function schedule the tty resize update.
786 *
787 * Locking: Locking free; the function MUST be called holding hp->lock
788 */
789void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
790{
791 hp->ws = ws;
792 schedule_work(&hp->tty_resize);
793}
794EXPORT_SYMBOL_GPL(__hvc_resize);
795
796/*
797 * This kthread is either polling or interrupt driven. This is determined by
798 * calling hvc_poll() who determines whether a console adapter support
799 * interrupts.
800 */
801static int khvcd(void *unused)
802{
803 int poll_mask;
804 struct hvc_struct *hp;
805
806 set_freezable();
807 do {
808 poll_mask = 0;
809 hvc_kicked = 0;
810 try_to_freeze();
811 wmb();
812 if (!cpus_are_in_xmon()) {
813 mutex_lock(&hvc_structs_mutex);
814 list_for_each_entry(hp, &hvc_structs, next) {
815 poll_mask |= __hvc_poll(hp, true);
816 cond_resched();
817 }
818 mutex_unlock(&hvc_structs_mutex);
819 } else
820 poll_mask |= HVC_POLL_READ;
821 if (hvc_kicked)
822 continue;
823 set_current_state(TASK_INTERRUPTIBLE);
824 if (!hvc_kicked) {
825 if (poll_mask == 0)
826 schedule();
827 else {
828 unsigned long j_timeout;
829
830 if (timeout < MAX_TIMEOUT)
831 timeout += (timeout >> 6) + 1;
832
833 /*
834 * We don't use msleep_interruptible otherwise
835 * "kick" will fail to wake us up
836 */
837 j_timeout = msecs_to_jiffies(timeout) + 1;
838 schedule_timeout_interruptible(j_timeout);
839 }
840 }
841 __set_current_state(TASK_RUNNING);
842 } while (!kthread_should_stop());
843
844 return 0;
845}
846
847static int hvc_tiocmget(struct tty_struct *tty)
848{
849 struct hvc_struct *hp = tty->driver_data;
850
851 if (!hp || !hp->ops->tiocmget)
852 return -EINVAL;
853 return hp->ops->tiocmget(hp);
854}
855
856static int hvc_tiocmset(struct tty_struct *tty,
857 unsigned int set, unsigned int clear)
858{
859 struct hvc_struct *hp = tty->driver_data;
860
861 if (!hp || !hp->ops->tiocmset)
862 return -EINVAL;
863 return hp->ops->tiocmset(hp, set, clear);
864}
865
866#ifdef CONFIG_CONSOLE_POLL
867static int hvc_poll_init(struct tty_driver *driver, int line, char *options)
868{
869 return 0;
870}
871
872static int hvc_poll_get_char(struct tty_driver *driver, int line)
873{
874 struct tty_struct *tty = driver->ttys[0];
875 struct hvc_struct *hp = tty->driver_data;
876 int n;
877 char ch;
878
879 n = hp->ops->get_chars(hp->vtermno, &ch, 1);
880
881 if (n <= 0)
882 return NO_POLL_CHAR;
883
884 return ch;
885}
886
887static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
888{
889 struct tty_struct *tty = driver->ttys[0];
890 struct hvc_struct *hp = tty->driver_data;
891 int n;
892
893 do {
894 n = hp->ops->put_chars(hp->vtermno, &ch, 1);
895 } while (n <= 0);
896}
897#endif
898
899static const struct tty_operations hvc_ops = {
900 .install = hvc_install,
901 .open = hvc_open,
902 .close = hvc_close,
903 .cleanup = hvc_cleanup,
904 .write = hvc_write,
905 .hangup = hvc_hangup,
906 .unthrottle = hvc_unthrottle,
907 .write_room = hvc_write_room,
908 .chars_in_buffer = hvc_chars_in_buffer,
909 .tiocmget = hvc_tiocmget,
910 .tiocmset = hvc_tiocmset,
911#ifdef CONFIG_CONSOLE_POLL
912 .poll_init = hvc_poll_init,
913 .poll_get_char = hvc_poll_get_char,
914 .poll_put_char = hvc_poll_put_char,
915#endif
916};
917
918static const struct tty_port_operations hvc_port_ops = {
919 .destruct = hvc_port_destruct,
920};
921
922struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
923 const struct hv_ops *ops,
924 int outbuf_size)
925{
926 struct hvc_struct *hp;
927 int i;
928
929 /* We wait until a driver actually comes along */
930 if (atomic_inc_not_zero(&hvc_needs_init)) {
931 int err = hvc_init();
932 if (err)
933 return ERR_PTR(err);
934 }
935
936 hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
937 GFP_KERNEL);
938 if (!hp)
939 return ERR_PTR(-ENOMEM);
940
941 hp->vtermno = vtermno;
942 hp->data = data;
943 hp->ops = ops;
944 hp->outbuf_size = outbuf_size;
945 hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
946
947 tty_port_init(&hp->port);
948 hp->port.ops = &hvc_port_ops;
949
950 INIT_WORK(&hp->tty_resize, hvc_set_winsz);
951 spin_lock_init(&hp->lock);
952 mutex_lock(&hvc_structs_mutex);
953
954 /*
955 * find index to use:
956 * see if this vterm id matches one registered for console.
957 */
958 for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
959 if (vtermnos[i] == hp->vtermno &&
960 cons_ops[i] == hp->ops)
961 break;
962
963 /* no matching slot, just use a counter */
964 if (i >= MAX_NR_HVC_CONSOLES)
965 i = ++last_hvc;
966
967 hp->index = i;
968 cons_ops[i] = ops;
969 vtermnos[i] = vtermno;
970
971 list_add_tail(&(hp->next), &hvc_structs);
972 mutex_unlock(&hvc_structs_mutex);
973
974 /* check if we need to re-register the kernel console */
975 hvc_check_console(i);
976
977 return hp;
978}
979EXPORT_SYMBOL_GPL(hvc_alloc);
980
981int hvc_remove(struct hvc_struct *hp)
982{
983 unsigned long flags;
984 struct tty_struct *tty;
985
986 tty = tty_port_tty_get(&hp->port);
987
988 console_lock();
989 spin_lock_irqsave(&hp->lock, flags);
990 if (hp->index < MAX_NR_HVC_CONSOLES) {
991 vtermnos[hp->index] = -1;
992 cons_ops[hp->index] = NULL;
993 }
994
995 /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
996
997 spin_unlock_irqrestore(&hp->lock, flags);
998 console_unlock();
999
1000 /*
1001 * We 'put' the instance that was grabbed when the kref instance
1002 * was initialized using kref_init(). Let the last holder of this
1003 * kref cause it to be removed, which will probably be the tty_vhangup
1004 * below.
1005 */
1006 tty_port_put(&hp->port);
1007
1008 /*
1009 * This function call will auto chain call hvc_hangup.
1010 */
1011 if (tty) {
1012 tty_vhangup(tty);
1013 tty_kref_put(tty);
1014 }
1015 return 0;
1016}
1017EXPORT_SYMBOL_GPL(hvc_remove);
1018
1019/* Driver initialization: called as soon as someone uses hvc_alloc(). */
1020static int hvc_init(void)
1021{
1022 struct tty_driver *drv;
1023 int err;
1024
1025 /* We need more than hvc_count adapters due to hotplug additions. */
1026 drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
1027 if (!drv) {
1028 err = -ENOMEM;
1029 goto out;
1030 }
1031
1032 drv->driver_name = "hvc";
1033 drv->name = "hvc";
1034 drv->major = HVC_MAJOR;
1035 drv->minor_start = HVC_MINOR;
1036 drv->type = TTY_DRIVER_TYPE_SYSTEM;
1037 drv->init_termios = tty_std_termios;
1038 drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
1039 tty_set_operations(drv, &hvc_ops);
1040
1041 /* Always start the kthread because there can be hotplug vty adapters
1042 * added later. */
1043 hvc_task = kthread_run(khvcd, NULL, "khvcd");
1044 if (IS_ERR(hvc_task)) {
1045 printk(KERN_ERR "Couldn't create kthread for console.\n");
1046 err = PTR_ERR(hvc_task);
1047 goto put_tty;
1048 }
1049
1050 err = tty_register_driver(drv);
1051 if (err) {
1052 printk(KERN_ERR "Couldn't register hvc console driver\n");
1053 goto stop_thread;
1054 }
1055
1056 /*
1057 * Make sure tty is fully registered before allowing it to be
1058 * found by hvc_console_device.
1059 */
1060 smp_mb();
1061 hvc_driver = drv;
1062 return 0;
1063
1064stop_thread:
1065 kthread_stop(hvc_task);
1066 hvc_task = NULL;
1067put_tty:
1068 put_tty_driver(drv);
1069out:
1070 return err;
1071}
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}