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