xref: /openbmc/linux/drivers/tty/hvc/hvc_console.c (revision c819e2cf)
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 
68 static struct tty_driver *hvc_driver;
69 static struct task_struct *hvc_task;
70 
71 /* Picks up late kicks after list walk but before schedule() */
72 static int hvc_kicked;
73 
74 /* hvc_init is triggered from hvc_alloc, i.e. only when actually used */
75 static atomic_t hvc_needs_init __read_mostly = ATOMIC_INIT(-1);
76 
77 static int hvc_init(void);
78 
79 #ifdef CONFIG_MAGIC_SYSRQ
80 static int sysrq_pressed;
81 #endif
82 
83 /* dynamic list of hvc_struct instances */
84 static LIST_HEAD(hvc_structs);
85 
86 /*
87  * Protect the list of hvc_struct instances from inserts and removals during
88  * list traversal.
89  */
90 static 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  */
97 static 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  */
104 static 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  */
134 static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
135 static 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 
143 static 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 
184 static 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 
193 static 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 
204 static 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  */
228 static int __init hvc_console_init(void)
229 {
230 	register_console(&hvc_console);
231 	return 0;
232 }
233 console_initcall(hvc_console_init);
234 
235 /* callback when the kboject ref count reaches zero. */
236 static 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 
252 static 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  */
272 int 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 }
301 EXPORT_SYMBOL_GPL(hvc_instantiate);
302 
303 /* Wake the sleeping khvcd */
304 void hvc_kick(void)
305 {
306 	hvc_kicked = 1;
307 	wake_up_process(hvc_task);
308 }
309 EXPORT_SYMBOL_GPL(hvc_kick);
310 
311 static void hvc_unthrottle(struct tty_struct *tty)
312 {
313 	hvc_kick();
314 }
315 
316 static 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  */
337 static 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 
380 static 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 
429 static 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 
436 static 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  */
473 static 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 
496 static 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  */
546 static 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  */
572 static 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 
582 static 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)
601 static u32 timeout = MIN_TIMEOUT;
602 
603 #define HVC_POLL_READ	0x00000001
604 #define HVC_POLL_WRITE	0x00000002
605 
606 int 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 }
713 EXPORT_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  */
725 void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
726 {
727 	hp->ws = ws;
728 	schedule_work(&hp->tty_resize);
729 }
730 EXPORT_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  */
737 static 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 				unsigned long j_timeout;
764 
765 				if (timeout < MAX_TIMEOUT)
766 					timeout += (timeout >> 6) + 1;
767 
768 				/*
769 				 * We don't use msleep_interruptible otherwise
770 				 * "kick" will fail to wake us up
771 				 */
772 				j_timeout = msecs_to_jiffies(timeout) + 1;
773 				schedule_timeout_interruptible(j_timeout);
774 			}
775 		}
776 		__set_current_state(TASK_RUNNING);
777 	} while (!kthread_should_stop());
778 
779 	return 0;
780 }
781 
782 static int hvc_tiocmget(struct tty_struct *tty)
783 {
784 	struct hvc_struct *hp = tty->driver_data;
785 
786 	if (!hp || !hp->ops->tiocmget)
787 		return -EINVAL;
788 	return hp->ops->tiocmget(hp);
789 }
790 
791 static int hvc_tiocmset(struct tty_struct *tty,
792 			unsigned int set, unsigned int clear)
793 {
794 	struct hvc_struct *hp = tty->driver_data;
795 
796 	if (!hp || !hp->ops->tiocmset)
797 		return -EINVAL;
798 	return hp->ops->tiocmset(hp, set, clear);
799 }
800 
801 #ifdef CONFIG_CONSOLE_POLL
802 static int hvc_poll_init(struct tty_driver *driver, int line, char *options)
803 {
804 	return 0;
805 }
806 
807 static int hvc_poll_get_char(struct tty_driver *driver, int line)
808 {
809 	struct tty_struct *tty = driver->ttys[0];
810 	struct hvc_struct *hp = tty->driver_data;
811 	int n;
812 	char ch;
813 
814 	n = hp->ops->get_chars(hp->vtermno, &ch, 1);
815 
816 	if (n == 0)
817 		return NO_POLL_CHAR;
818 
819 	return ch;
820 }
821 
822 static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
823 {
824 	struct tty_struct *tty = driver->ttys[0];
825 	struct hvc_struct *hp = tty->driver_data;
826 	int n;
827 
828 	do {
829 		n = hp->ops->put_chars(hp->vtermno, &ch, 1);
830 	} while (n <= 0);
831 }
832 #endif
833 
834 static const struct tty_operations hvc_ops = {
835 	.install = hvc_install,
836 	.open = hvc_open,
837 	.close = hvc_close,
838 	.cleanup = hvc_cleanup,
839 	.write = hvc_write,
840 	.hangup = hvc_hangup,
841 	.unthrottle = hvc_unthrottle,
842 	.write_room = hvc_write_room,
843 	.chars_in_buffer = hvc_chars_in_buffer,
844 	.tiocmget = hvc_tiocmget,
845 	.tiocmset = hvc_tiocmset,
846 #ifdef CONFIG_CONSOLE_POLL
847 	.poll_init = hvc_poll_init,
848 	.poll_get_char = hvc_poll_get_char,
849 	.poll_put_char = hvc_poll_put_char,
850 #endif
851 };
852 
853 static const struct tty_port_operations hvc_port_ops = {
854 	.destruct = hvc_port_destruct,
855 };
856 
857 struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
858 			     const struct hv_ops *ops,
859 			     int outbuf_size)
860 {
861 	struct hvc_struct *hp;
862 	int i;
863 
864 	/* We wait until a driver actually comes along */
865 	if (atomic_inc_not_zero(&hvc_needs_init)) {
866 		int err = hvc_init();
867 		if (err)
868 			return ERR_PTR(err);
869 	}
870 
871 	hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
872 			GFP_KERNEL);
873 	if (!hp)
874 		return ERR_PTR(-ENOMEM);
875 
876 	hp->vtermno = vtermno;
877 	hp->data = data;
878 	hp->ops = ops;
879 	hp->outbuf_size = outbuf_size;
880 	hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
881 
882 	tty_port_init(&hp->port);
883 	hp->port.ops = &hvc_port_ops;
884 
885 	INIT_WORK(&hp->tty_resize, hvc_set_winsz);
886 	spin_lock_init(&hp->lock);
887 	spin_lock(&hvc_structs_lock);
888 
889 	/*
890 	 * find index to use:
891 	 * see if this vterm id matches one registered for console.
892 	 */
893 	for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
894 		if (vtermnos[i] == hp->vtermno &&
895 		    cons_ops[i] == hp->ops)
896 			break;
897 
898 	/* no matching slot, just use a counter */
899 	if (i >= MAX_NR_HVC_CONSOLES)
900 		i = ++last_hvc;
901 
902 	hp->index = i;
903 	cons_ops[i] = ops;
904 	vtermnos[i] = vtermno;
905 
906 	list_add_tail(&(hp->next), &hvc_structs);
907 	spin_unlock(&hvc_structs_lock);
908 
909 	/* check if we need to re-register the kernel console */
910 	hvc_check_console(i);
911 
912 	return hp;
913 }
914 EXPORT_SYMBOL_GPL(hvc_alloc);
915 
916 int hvc_remove(struct hvc_struct *hp)
917 {
918 	unsigned long flags;
919 	struct tty_struct *tty;
920 
921 	tty = tty_port_tty_get(&hp->port);
922 
923 	spin_lock_irqsave(&hp->lock, flags);
924 	if (hp->index < MAX_NR_HVC_CONSOLES) {
925 		console_lock();
926 		vtermnos[hp->index] = -1;
927 		cons_ops[hp->index] = NULL;
928 		console_unlock();
929 	}
930 
931 	/* Don't whack hp->irq because tty_hangup() will need to free the irq. */
932 
933 	spin_unlock_irqrestore(&hp->lock, flags);
934 
935 	/*
936 	 * We 'put' the instance that was grabbed when the kref instance
937 	 * was initialized using kref_init().  Let the last holder of this
938 	 * kref cause it to be removed, which will probably be the tty_vhangup
939 	 * below.
940 	 */
941 	tty_port_put(&hp->port);
942 
943 	/*
944 	 * This function call will auto chain call hvc_hangup.
945 	 */
946 	if (tty) {
947 		tty_vhangup(tty);
948 		tty_kref_put(tty);
949 	}
950 	return 0;
951 }
952 EXPORT_SYMBOL_GPL(hvc_remove);
953 
954 /* Driver initialization: called as soon as someone uses hvc_alloc(). */
955 static int hvc_init(void)
956 {
957 	struct tty_driver *drv;
958 	int err;
959 
960 	/* We need more than hvc_count adapters due to hotplug additions. */
961 	drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
962 	if (!drv) {
963 		err = -ENOMEM;
964 		goto out;
965 	}
966 
967 	drv->driver_name = "hvc";
968 	drv->name = "hvc";
969 	drv->major = HVC_MAJOR;
970 	drv->minor_start = HVC_MINOR;
971 	drv->type = TTY_DRIVER_TYPE_SYSTEM;
972 	drv->init_termios = tty_std_termios;
973 	drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
974 	tty_set_operations(drv, &hvc_ops);
975 
976 	/* Always start the kthread because there can be hotplug vty adapters
977 	 * added later. */
978 	hvc_task = kthread_run(khvcd, NULL, "khvcd");
979 	if (IS_ERR(hvc_task)) {
980 		printk(KERN_ERR "Couldn't create kthread for console.\n");
981 		err = PTR_ERR(hvc_task);
982 		goto put_tty;
983 	}
984 
985 	err = tty_register_driver(drv);
986 	if (err) {
987 		printk(KERN_ERR "Couldn't register hvc console driver\n");
988 		goto stop_thread;
989 	}
990 
991 	/*
992 	 * Make sure tty is fully registered before allowing it to be
993 	 * found by hvc_console_device.
994 	 */
995 	smp_mb();
996 	hvc_driver = drv;
997 	return 0;
998 
999 stop_thread:
1000 	kthread_stop(hvc_task);
1001 	hvc_task = NULL;
1002 put_tty:
1003 	put_tty_driver(drv);
1004 out:
1005 	return err;
1006 }
1007 
1008 /* This isn't particularly necessary due to this being a console driver
1009  * but it is nice to be thorough.
1010  */
1011 static void __exit hvc_exit(void)
1012 {
1013 	if (hvc_driver) {
1014 		kthread_stop(hvc_task);
1015 
1016 		tty_unregister_driver(hvc_driver);
1017 		/* return tty_struct instances allocated in hvc_init(). */
1018 		put_tty_driver(hvc_driver);
1019 		unregister_console(&hvc_console);
1020 	}
1021 }
1022 module_exit(hvc_exit);
1023