Root/drivers/tty/hvc/hvc_console.c

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            tty_port_get(&hp->port);
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 hvc_port_destruct(struct tty_port *port)
233{
234    struct hvc_struct *hp = container_of(port, struct hvc_struct, port);
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
248static void hvc_check_console(int index)
249{
250    /* Already enabled, bail out */
251    if (hvc_console.flags & CON_ENABLED)
252        return;
253
254     /* If this index is what the user requested, then register
255     * now (setup won't fail at this point). It's ok to just
256     * call register again if previously .setup failed.
257     */
258    if (index == hvc_console.index)
259        register_console(&hvc_console);
260}
261
262/*
263 * hvc_instantiate() is an early console discovery method which locates
264 * consoles * prior to the vio subsystem discovering them. Hotplugged
265 * vty adapters do NOT get an hvc_instantiate() callback since they
266 * appear after early console init.
267 */
268int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
269{
270    struct hvc_struct *hp;
271
272    if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
273        return -1;
274
275    if (vtermnos[index] != -1)
276        return -1;
277
278    /* make sure no no tty has been registered in this index */
279    hp = hvc_get_by_index(index);
280    if (hp) {
281        tty_port_put(&hp->port);
282        return -1;
283    }
284
285    vtermnos[index] = vtermno;
286    cons_ops[index] = ops;
287
288    /* reserve all indices up to and including this index */
289    if (last_hvc < index)
290        last_hvc = index;
291
292    /* check if we need to re-register the kernel console */
293    hvc_check_console(index);
294
295    return 0;
296}
297EXPORT_SYMBOL_GPL(hvc_instantiate);
298
299/* Wake the sleeping khvcd */
300void hvc_kick(void)
301{
302    hvc_kicked = 1;
303    wake_up_process(hvc_task);
304}
305EXPORT_SYMBOL_GPL(hvc_kick);
306
307static void hvc_unthrottle(struct tty_struct *tty)
308{
309    hvc_kick();
310}
311
312static int hvc_install(struct tty_driver *driver, struct tty_struct *tty)
313{
314    struct hvc_struct *hp;
315    int rc;
316
317    /* Auto increments kref reference if found. */
318    if (!(hp = hvc_get_by_index(tty->index)))
319        return -ENODEV;
320
321    tty->driver_data = hp;
322
323    rc = tty_port_install(&hp->port, driver, tty);
324    if (rc)
325        tty_port_put(&hp->port);
326    return rc;
327}
328
329/*
330 * The TTY interface won't be used until after the vio layer has exposed the vty
331 * adapter to the kernel.
332 */
333static int hvc_open(struct tty_struct *tty, struct file * filp)
334{
335    struct hvc_struct *hp = tty->driver_data;
336    unsigned long flags;
337    int rc = 0;
338
339    spin_lock_irqsave(&hp->port.lock, flags);
340    /* Check and then increment for fast path open. */
341    if (hp->port.count++ > 0) {
342        spin_unlock_irqrestore(&hp->port.lock, flags);
343        hvc_kick();
344        return 0;
345    } /* else count == 0 */
346    spin_unlock_irqrestore(&hp->port.lock, flags);
347
348    tty_port_tty_set(&hp->port, tty);
349
350    if (hp->ops->notifier_add)
351        rc = hp->ops->notifier_add(hp, hp->data);
352
353    /*
354     * If the notifier fails we return an error. The tty layer
355     * will call hvc_close() after a failed open but we don't want to clean
356     * up there so we'll clean up here and clear out the previously set
357     * tty fields and return the kref reference.
358     */
359    if (rc) {
360        tty_port_tty_set(&hp->port, NULL);
361        tty->driver_data = NULL;
362        tty_port_put(&hp->port);
363        printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
364    }
365    /* Force wakeup of the polling thread */
366    hvc_kick();
367
368    return rc;
369}
370
371static void hvc_close(struct tty_struct *tty, struct file * filp)
372{
373    struct hvc_struct *hp;
374    unsigned long flags;
375
376    if (tty_hung_up_p(filp))
377        return;
378
379    /*
380     * No driver_data means that this close was issued after a failed
381     * hvc_open by the tty layer's release_dev() function and we can just
382     * exit cleanly because the kref reference wasn't made.
383     */
384    if (!tty->driver_data)
385        return;
386
387    hp = tty->driver_data;
388
389    spin_lock_irqsave(&hp->port.lock, flags);
390
391    if (--hp->port.count == 0) {
392        spin_unlock_irqrestore(&hp->port.lock, flags);
393        /* We are done with the tty pointer now. */
394        tty_port_tty_set(&hp->port, NULL);
395
396        if (hp->ops->notifier_del)
397            hp->ops->notifier_del(hp, hp->data);
398
399        /* cancel pending tty resize work */
400        cancel_work_sync(&hp->tty_resize);
401
402        /*
403         * Chain calls chars_in_buffer() and returns immediately if
404         * there is no buffered data otherwise sleeps on a wait queue
405         * waking periodically to check chars_in_buffer().
406         */
407        tty_wait_until_sent_from_close(tty, HVC_CLOSE_WAIT);
408    } else {
409        if (hp->port.count < 0)
410            printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
411                hp->vtermno, hp->port.count);
412        spin_unlock_irqrestore(&hp->port.lock, flags);
413    }
414}
415
416static void hvc_cleanup(struct tty_struct *tty)
417{
418    struct hvc_struct *hp = tty->driver_data;
419
420    tty_port_put(&hp->port);
421}
422
423static void hvc_hangup(struct tty_struct *tty)
424{
425    struct hvc_struct *hp = tty->driver_data;
426    unsigned long flags;
427
428    if (!hp)
429        return;
430
431    /* cancel pending tty resize work */
432    cancel_work_sync(&hp->tty_resize);
433
434    spin_lock_irqsave(&hp->port.lock, flags);
435
436    /*
437     * The N_TTY line discipline has problems such that in a close vs
438     * open->hangup case this can be called after the final close so prevent
439     * that from happening for now.
440     */
441    if (hp->port.count <= 0) {
442        spin_unlock_irqrestore(&hp->port.lock, flags);
443        return;
444    }
445
446    hp->port.count = 0;
447    spin_unlock_irqrestore(&hp->port.lock, flags);
448    tty_port_tty_set(&hp->port, NULL);
449
450    hp->n_outbuf = 0;
451
452    if (hp->ops->notifier_hangup)
453        hp->ops->notifier_hangup(hp, hp->data);
454}
455
456/*
457 * Push buffered characters whether they were just recently buffered or waiting
458 * on a blocked hypervisor. Call this function with hp->lock held.
459 */
460static int hvc_push(struct hvc_struct *hp)
461{
462    int n;
463
464    n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
465    if (n <= 0) {
466        if (n == 0 || n == -EAGAIN) {
467            hp->do_wakeup = 1;
468            return 0;
469        }
470        /* throw away output on error; this happens when
471           there is no session connected to the vterm. */
472        hp->n_outbuf = 0;
473    } else
474        hp->n_outbuf -= n;
475    if (hp->n_outbuf > 0)
476        memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
477    else
478        hp->do_wakeup = 1;
479
480    return n;
481}
482
483static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
484{
485    struct hvc_struct *hp = tty->driver_data;
486    unsigned long flags;
487    int rsize, written = 0;
488
489    /* This write was probably executed during a tty close. */
490    if (!hp)
491        return -EPIPE;
492
493    /* FIXME what's this (unprotected) check for? */
494    if (hp->port.count <= 0)
495        return -EIO;
496
497    spin_lock_irqsave(&hp->lock, flags);
498
499    /* Push pending writes */
500    if (hp->n_outbuf > 0)
501        hvc_push(hp);
502
503    while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
504        if (rsize > count)
505            rsize = count;
506        memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
507        count -= rsize;
508        buf += rsize;
509        hp->n_outbuf += rsize;
510        written += rsize;
511        hvc_push(hp);
512    }
513    spin_unlock_irqrestore(&hp->lock, flags);
514
515    /*
516     * Racy, but harmless, kick thread if there is still pending data.
517     */
518    if (hp->n_outbuf)
519        hvc_kick();
520
521    return written;
522}
523
524/**
525 * hvc_set_winsz() - Resize the hvc tty terminal window.
526 * @work: work structure.
527 *
528 * The routine shall not be called within an atomic context because it
529 * might sleep.
530 *
531 * Locking: hp->lock
532 */
533static void hvc_set_winsz(struct work_struct *work)
534{
535    struct hvc_struct *hp;
536    unsigned long hvc_flags;
537    struct tty_struct *tty;
538    struct winsize ws;
539
540    hp = container_of(work, struct hvc_struct, tty_resize);
541
542    tty = tty_port_tty_get(&hp->port);
543    if (!tty)
544        return;
545
546    spin_lock_irqsave(&hp->lock, hvc_flags);
547    ws = hp->ws;
548    spin_unlock_irqrestore(&hp->lock, hvc_flags);
549
550    tty_do_resize(tty, &ws);
551    tty_kref_put(tty);
552}
553
554/*
555 * This is actually a contract between the driver and the tty layer outlining
556 * how much write room the driver can guarantee will be sent OR BUFFERED. This
557 * driver MUST honor the return value.
558 */
559static int hvc_write_room(struct tty_struct *tty)
560{
561    struct hvc_struct *hp = tty->driver_data;
562
563    if (!hp)
564        return 0;
565
566    return hp->outbuf_size - hp->n_outbuf;
567}
568
569static int hvc_chars_in_buffer(struct tty_struct *tty)
570{
571    struct hvc_struct *hp = tty->driver_data;
572
573    if (!hp)
574        return 0;
575    return hp->n_outbuf;
576}
577
578/*
579 * timeout will vary between the MIN and MAX values defined here. By default
580 * and during console activity we will use a default MIN_TIMEOUT of 10. When
581 * the console is idle, we increase the timeout value on each pass through
582 * msleep until we reach the max. This may be noticeable as a brief (average
583 * one second) delay on the console before the console responds to input when
584 * there has been no input for some time.
585 */
586#define MIN_TIMEOUT (10)
587#define MAX_TIMEOUT (2000)
588static u32 timeout = MIN_TIMEOUT;
589
590#define HVC_POLL_READ 0x00000001
591#define HVC_POLL_WRITE 0x00000002
592
593int hvc_poll(struct hvc_struct *hp)
594{
595    struct tty_struct *tty;
596    int i, n, poll_mask = 0;
597    char buf[N_INBUF] __ALIGNED__;
598    unsigned long flags;
599    int read_total = 0;
600    int written_total = 0;
601
602    spin_lock_irqsave(&hp->lock, flags);
603
604    /* Push pending writes */
605    if (hp->n_outbuf > 0)
606        written_total = hvc_push(hp);
607
608    /* Reschedule us if still some write pending */
609    if (hp->n_outbuf > 0) {
610        poll_mask |= HVC_POLL_WRITE;
611        /* If hvc_push() was not able to write, sleep a few msecs */
612        timeout = (written_total) ? 0 : MIN_TIMEOUT;
613    }
614
615    /* No tty attached, just skip */
616    tty = tty_port_tty_get(&hp->port);
617    if (tty == NULL)
618        goto bail;
619
620    /* Now check if we can get data (are we throttled ?) */
621    if (test_bit(TTY_THROTTLED, &tty->flags))
622        goto throttled;
623
624    /* If we aren't notifier driven and aren't throttled, we always
625     * request a reschedule
626     */
627    if (!hp->irq_requested)
628        poll_mask |= HVC_POLL_READ;
629
630    /* Read data if any */
631    for (;;) {
632        int count = tty_buffer_request_room(&hp->port, N_INBUF);
633
634        /* If flip is full, just reschedule a later read */
635        if (count == 0) {
636            poll_mask |= HVC_POLL_READ;
637            break;
638        }
639
640        n = hp->ops->get_chars(hp->vtermno, buf, count);
641        if (n <= 0) {
642            /* Hangup the tty when disconnected from host */
643            if (n == -EPIPE) {
644                spin_unlock_irqrestore(&hp->lock, flags);
645                tty_hangup(tty);
646                spin_lock_irqsave(&hp->lock, flags);
647            } else if ( n == -EAGAIN ) {
648                /*
649                 * Some back-ends can only ensure a certain min
650                 * num of bytes read, which may be > 'count'.
651                 * Let the tty clear the flip buff to make room.
652                 */
653                poll_mask |= HVC_POLL_READ;
654            }
655            break;
656        }
657        for (i = 0; i < n; ++i) {
658#ifdef CONFIG_MAGIC_SYSRQ
659            if (hp->index == hvc_console.index) {
660                /* Handle the SysRq Hack */
661                /* XXX should support a sequence */
662                if (buf[i] == '\x0f') { /* ^O */
663                    /* if ^O is pressed again, reset
664                     * sysrq_pressed and flip ^O char */
665                    sysrq_pressed = !sysrq_pressed;
666                    if (sysrq_pressed)
667                        continue;
668                } else if (sysrq_pressed) {
669                    handle_sysrq(buf[i]);
670                    sysrq_pressed = 0;
671                    continue;
672                }
673            }
674#endif /* CONFIG_MAGIC_SYSRQ */
675            tty_insert_flip_char(&hp->port, buf[i], 0);
676        }
677
678        read_total += n;
679    }
680 throttled:
681    /* Wakeup write queue if necessary */
682    if (hp->do_wakeup) {
683        hp->do_wakeup = 0;
684        tty_wakeup(tty);
685    }
686 bail:
687    spin_unlock_irqrestore(&hp->lock, flags);
688
689    if (read_total) {
690        /* Activity is occurring, so reset the polling backoff value to
691           a minimum for performance. */
692        timeout = MIN_TIMEOUT;
693
694        tty_flip_buffer_push(&hp->port);
695    }
696    tty_kref_put(tty);
697
698    return poll_mask;
699}
700EXPORT_SYMBOL_GPL(hvc_poll);
701
702/**
703 * __hvc_resize() - Update terminal window size information.
704 * @hp: HVC console pointer
705 * @ws: Terminal window size structure
706 *
707 * Stores the specified window size information in the hvc structure of @hp.
708 * The function schedule the tty resize update.
709 *
710 * Locking: Locking free; the function MUST be called holding hp->lock
711 */
712void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
713{
714    hp->ws = ws;
715    schedule_work(&hp->tty_resize);
716}
717EXPORT_SYMBOL_GPL(__hvc_resize);
718
719/*
720 * This kthread is either polling or interrupt driven. This is determined by
721 * calling hvc_poll() who determines whether a console adapter support
722 * interrupts.
723 */
724static int khvcd(void *unused)
725{
726    int poll_mask;
727    struct hvc_struct *hp;
728
729    set_freezable();
730    do {
731        poll_mask = 0;
732        hvc_kicked = 0;
733        try_to_freeze();
734        wmb();
735        if (!cpus_are_in_xmon()) {
736            spin_lock(&hvc_structs_lock);
737            list_for_each_entry(hp, &hvc_structs, next) {
738                poll_mask |= hvc_poll(hp);
739            }
740            spin_unlock(&hvc_structs_lock);
741        } else
742            poll_mask |= HVC_POLL_READ;
743        if (hvc_kicked)
744            continue;
745        set_current_state(TASK_INTERRUPTIBLE);
746        if (!hvc_kicked) {
747            if (poll_mask == 0)
748                schedule();
749            else {
750                if (timeout < MAX_TIMEOUT)
751                    timeout += (timeout >> 6) + 1;
752
753                msleep_interruptible(timeout);
754            }
755        }
756        __set_current_state(TASK_RUNNING);
757    } while (!kthread_should_stop());
758
759    return 0;
760}
761
762static int hvc_tiocmget(struct tty_struct *tty)
763{
764    struct hvc_struct *hp = tty->driver_data;
765
766    if (!hp || !hp->ops->tiocmget)
767        return -EINVAL;
768    return hp->ops->tiocmget(hp);
769}
770
771static int hvc_tiocmset(struct tty_struct *tty,
772            unsigned int set, unsigned int clear)
773{
774    struct hvc_struct *hp = tty->driver_data;
775
776    if (!hp || !hp->ops->tiocmset)
777        return -EINVAL;
778    return hp->ops->tiocmset(hp, set, clear);
779}
780
781#ifdef CONFIG_CONSOLE_POLL
782int hvc_poll_init(struct tty_driver *driver, int line, char *options)
783{
784    return 0;
785}
786
787static int hvc_poll_get_char(struct tty_driver *driver, int line)
788{
789    struct tty_struct *tty = driver->ttys[0];
790    struct hvc_struct *hp = tty->driver_data;
791    int n;
792    char ch;
793
794    n = hp->ops->get_chars(hp->vtermno, &ch, 1);
795
796    if (n == 0)
797        return NO_POLL_CHAR;
798
799    return ch;
800}
801
802static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
803{
804    struct tty_struct *tty = driver->ttys[0];
805    struct hvc_struct *hp = tty->driver_data;
806    int n;
807
808    do {
809        n = hp->ops->put_chars(hp->vtermno, &ch, 1);
810    } while (n <= 0);
811}
812#endif
813
814static const struct tty_operations hvc_ops = {
815    .install = hvc_install,
816    .open = hvc_open,
817    .close = hvc_close,
818    .cleanup = hvc_cleanup,
819    .write = hvc_write,
820    .hangup = hvc_hangup,
821    .unthrottle = hvc_unthrottle,
822    .write_room = hvc_write_room,
823    .chars_in_buffer = hvc_chars_in_buffer,
824    .tiocmget = hvc_tiocmget,
825    .tiocmset = hvc_tiocmset,
826#ifdef CONFIG_CONSOLE_POLL
827    .poll_init = hvc_poll_init,
828    .poll_get_char = hvc_poll_get_char,
829    .poll_put_char = hvc_poll_put_char,
830#endif
831};
832
833static const struct tty_port_operations hvc_port_ops = {
834    .destruct = hvc_port_destruct,
835};
836
837struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
838                 const struct hv_ops *ops,
839                 int outbuf_size)
840{
841    struct hvc_struct *hp;
842    int i;
843
844    /* We wait until a driver actually comes along */
845    if (!hvc_driver) {
846        int err = hvc_init();
847        if (err)
848            return ERR_PTR(err);
849    }
850
851    hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
852            GFP_KERNEL);
853    if (!hp)
854        return ERR_PTR(-ENOMEM);
855
856    hp->vtermno = vtermno;
857    hp->data = data;
858    hp->ops = ops;
859    hp->outbuf_size = outbuf_size;
860    hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
861
862    tty_port_init(&hp->port);
863    hp->port.ops = &hvc_port_ops;
864
865    INIT_WORK(&hp->tty_resize, hvc_set_winsz);
866    spin_lock_init(&hp->lock);
867    spin_lock(&hvc_structs_lock);
868
869    /*
870     * find index to use:
871     * see if this vterm id matches one registered for console.
872     */
873    for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
874        if (vtermnos[i] == hp->vtermno &&
875            cons_ops[i] == hp->ops)
876            break;
877
878    /* no matching slot, just use a counter */
879    if (i >= MAX_NR_HVC_CONSOLES)
880        i = ++last_hvc;
881
882    hp->index = i;
883    cons_ops[i] = ops;
884    vtermnos[i] = vtermno;
885
886    list_add_tail(&(hp->next), &hvc_structs);
887    spin_unlock(&hvc_structs_lock);
888
889    /* check if we need to re-register the kernel console */
890    hvc_check_console(i);
891
892    return hp;
893}
894EXPORT_SYMBOL_GPL(hvc_alloc);
895
896int hvc_remove(struct hvc_struct *hp)
897{
898    unsigned long flags;
899    struct tty_struct *tty;
900
901    tty = tty_port_tty_get(&hp->port);
902
903    spin_lock_irqsave(&hp->lock, flags);
904    if (hp->index < MAX_NR_HVC_CONSOLES) {
905        console_lock();
906        vtermnos[hp->index] = -1;
907        cons_ops[hp->index] = NULL;
908        console_unlock();
909    }
910
911    /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
912
913    spin_unlock_irqrestore(&hp->lock, flags);
914
915    /*
916     * We 'put' the instance that was grabbed when the kref instance
917     * was initialized using kref_init(). Let the last holder of this
918     * kref cause it to be removed, which will probably be the tty_vhangup
919     * below.
920     */
921    tty_port_put(&hp->port);
922
923    /*
924     * This function call will auto chain call hvc_hangup.
925     */
926    if (tty) {
927        tty_vhangup(tty);
928        tty_kref_put(tty);
929    }
930    return 0;
931}
932EXPORT_SYMBOL_GPL(hvc_remove);
933
934/* Driver initialization: called as soon as someone uses hvc_alloc(). */
935static int hvc_init(void)
936{
937    struct tty_driver *drv;
938    int err;
939
940    /* We need more than hvc_count adapters due to hotplug additions. */
941    drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
942    if (!drv) {
943        err = -ENOMEM;
944        goto out;
945    }
946
947    drv->driver_name = "hvc";
948    drv->name = "hvc";
949    drv->major = HVC_MAJOR;
950    drv->minor_start = HVC_MINOR;
951    drv->type = TTY_DRIVER_TYPE_SYSTEM;
952    drv->init_termios = tty_std_termios;
953    drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
954    tty_set_operations(drv, &hvc_ops);
955
956    /* Always start the kthread because there can be hotplug vty adapters
957     * added later. */
958    hvc_task = kthread_run(khvcd, NULL, "khvcd");
959    if (IS_ERR(hvc_task)) {
960        printk(KERN_ERR "Couldn't create kthread for console.\n");
961        err = PTR_ERR(hvc_task);
962        goto put_tty;
963    }
964
965    err = tty_register_driver(drv);
966    if (err) {
967        printk(KERN_ERR "Couldn't register hvc console driver\n");
968        goto stop_thread;
969    }
970
971    /*
972     * Make sure tty is fully registered before allowing it to be
973     * found by hvc_console_device.
974     */
975    smp_mb();
976    hvc_driver = drv;
977    return 0;
978
979stop_thread:
980    kthread_stop(hvc_task);
981    hvc_task = NULL;
982put_tty:
983    put_tty_driver(drv);
984out:
985    return err;
986}
987
988/* This isn't particularly necessary due to this being a console driver
989 * but it is nice to be thorough.
990 */
991static void __exit hvc_exit(void)
992{
993    if (hvc_driver) {
994        kthread_stop(hvc_task);
995
996        tty_unregister_driver(hvc_driver);
997        /* return tty_struct instances allocated in hvc_init(). */
998        put_tty_driver(hvc_driver);
999        unregister_console(&hvc_console);
1000    }
1001}
1002module_exit(hvc_exit);
1003

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