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[/] [test_project/] [trunk/] [linux_sd_driver/] [drivers/] [char/] [hvc_console.c] - Blame information for rev 65

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1 62 marcus.erl
/*
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/kobject.h>
31
#include <linux/kthread.h>
32
#include <linux/list.h>
33
#include <linux/module.h>
34
#include <linux/major.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
 
43
#include <asm/uaccess.h>
44
 
45
#include "hvc_console.h"
46
 
47
#define HVC_MAJOR       229
48
#define HVC_MINOR       0
49
 
50
/*
51
 * Wait this long per iteration while trying to push buffered data to the
52
 * hypervisor before allowing the tty to complete a close operation.
53
 */
54
#define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
55
 
56
/*
57
 * These sizes are most efficient for vio, because they are the
58
 * native transfer size. We could make them selectable in the
59
 * future to better deal with backends that want other buffer sizes.
60
 */
61
#define N_OUTBUF        16
62
#define N_INBUF         16
63
 
64
#define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
65
 
66
static struct tty_driver *hvc_driver;
67
static struct task_struct *hvc_task;
68
 
69
/* Picks up late kicks after list walk but before schedule() */
70
static int hvc_kicked;
71
 
72
static int hvc_init(void);
73
 
74
#ifdef CONFIG_MAGIC_SYSRQ
75
static int sysrq_pressed;
76
#endif
77
 
78
struct hvc_struct {
79
        spinlock_t lock;
80
        int index;
81
        struct tty_struct *tty;
82
        unsigned int count;
83
        int do_wakeup;
84
        char *outbuf;
85
        int outbuf_size;
86
        int n_outbuf;
87
        uint32_t vtermno;
88
        struct hv_ops *ops;
89
        int irq_requested;
90
        int irq;
91
        struct list_head next;
92
        struct kobject kobj; /* ref count & hvc_struct lifetime */
93
};
94
 
95
/* dynamic list of hvc_struct instances */
96
static struct list_head hvc_structs = LIST_HEAD_INIT(hvc_structs);
97
 
98
/*
99
 * Protect the list of hvc_struct instances from inserts and removals during
100
 * list traversal.
101
 */
102
static DEFINE_SPINLOCK(hvc_structs_lock);
103
 
104
/*
105
 * This value is used to assign a tty->index value to a hvc_struct based
106
 * upon order of exposure via hvc_probe(), when we can not match it to
107
 * a console candidate registered with hvc_instantiate().
108
 */
109
static int last_hvc = -1;
110
 
111
/*
112
 * Do not call this function with either the hvc_structs_lock or the hvc_struct
113
 * lock held.  If successful, this function increments the kobject reference
114
 * count against the target hvc_struct so it should be released when finished.
115
 */
116
static struct hvc_struct *hvc_get_by_index(int index)
117
{
118
        struct hvc_struct *hp;
119
        unsigned long flags;
120
 
121
        spin_lock(&hvc_structs_lock);
122
 
123
        list_for_each_entry(hp, &hvc_structs, next) {
124
                spin_lock_irqsave(&hp->lock, flags);
125
                if (hp->index == index) {
126
                        kobject_get(&hp->kobj);
127
                        spin_unlock_irqrestore(&hp->lock, flags);
128
                        spin_unlock(&hvc_structs_lock);
129
                        return hp;
130
                }
131
                spin_unlock_irqrestore(&hp->lock, flags);
132
        }
133
        hp = NULL;
134
 
135
        spin_unlock(&hvc_structs_lock);
136
        return hp;
137
}
138
 
139
 
140
/*
141
 * Initial console vtermnos for console API usage prior to full console
142
 * initialization.  Any vty adapter outside this range will not have usable
143
 * console interfaces but can still be used as a tty device.  This has to be
144
 * static because kmalloc will not work during early console init.
145
 */
146
static struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
147
static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
148
        {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
149
 
150
/*
151
 * Console APIs, NOT TTY.  These APIs are available immediately when
152
 * hvc_console_setup() finds adapters.
153
 */
154
 
155
static void hvc_console_print(struct console *co, const char *b,
156
                              unsigned count)
157
{
158
        char c[N_OUTBUF] __ALIGNED__;
159
        unsigned i = 0, n = 0;
160
        int r, donecr = 0, index = co->index;
161
 
162
        /* Console access attempt outside of acceptable console range. */
163
        if (index >= MAX_NR_HVC_CONSOLES)
164
                return;
165
 
166
        /* This console adapter was removed so it is not usable. */
167
        if (vtermnos[index] < 0)
168
                return;
169
 
170
        while (count > 0 || i > 0) {
171
                if (count > 0 && i < sizeof(c)) {
172
                        if (b[n] == '\n' && !donecr) {
173
                                c[i++] = '\r';
174
                                donecr = 1;
175
                        } else {
176
                                c[i++] = b[n++];
177
                                donecr = 0;
178
                                --count;
179
                        }
180
                } else {
181
                        r = cons_ops[index]->put_chars(vtermnos[index], c, i);
182
                        if (r < 0) {
183
                                /* throw away chars on error */
184
                                i = 0;
185
                        } else if (r > 0) {
186
                                i -= r;
187
                                if (i > 0)
188
                                        memmove(c, c+r, i);
189
                        }
190
                }
191
        }
192
}
193
 
194
static struct tty_driver *hvc_console_device(struct console *c, int *index)
195
{
196
        if (vtermnos[c->index] == -1)
197
                return NULL;
198
 
199
        *index = c->index;
200
        return hvc_driver;
201
}
202
 
203
static int __init hvc_console_setup(struct console *co, char *options)
204
{
205
        if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
206
                return -ENODEV;
207
 
208
        if (vtermnos[co->index] == -1)
209
                return -ENODEV;
210
 
211
        return 0;
212
}
213
 
214
static struct console hvc_con_driver = {
215
        .name           = "hvc",
216
        .write          = hvc_console_print,
217
        .device         = hvc_console_device,
218
        .setup          = hvc_console_setup,
219
        .flags          = CON_PRINTBUFFER,
220
        .index          = -1,
221
};
222
 
223
/*
224
 * Early console initialization.  Precedes driver initialization.
225
 *
226
 * (1) we are first, and the user specified another driver
227
 * -- index will remain -1
228
 * (2) we are first and the user specified no driver
229
 * -- index will be set to 0, then we will fail setup.
230
 * (3)  we are first and the user specified our driver
231
 * -- index will be set to user specified driver, and we will fail
232
 * (4) we are after driver, and this initcall will register us
233
 * -- if the user didn't specify a driver then the console will match
234
 *
235
 * Note that for cases 2 and 3, we will match later when the io driver
236
 * calls hvc_instantiate() and call register again.
237
 */
238
static int __init hvc_console_init(void)
239
{
240
        register_console(&hvc_con_driver);
241
        return 0;
242
}
243
console_initcall(hvc_console_init);
244
 
245
/*
246
 * hvc_instantiate() is an early console discovery method which locates
247
 * consoles * prior to the vio subsystem discovering them.  Hotplugged
248
 * vty adapters do NOT get an hvc_instantiate() callback since they
249
 * appear after early console init.
250
 */
251
int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops)
252
{
253
        struct hvc_struct *hp;
254
 
255
        if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
256
                return -1;
257
 
258
        if (vtermnos[index] != -1)
259
                return -1;
260
 
261
        /* make sure no no tty has been registered in this index */
262
        hp = hvc_get_by_index(index);
263
        if (hp) {
264
                kobject_put(&hp->kobj);
265
                return -1;
266
        }
267
 
268
        vtermnos[index] = vtermno;
269
        cons_ops[index] = ops;
270
 
271
        /* reserve all indices up to and including this index */
272
        if (last_hvc < index)
273
                last_hvc = index;
274
 
275
        /* if this index is what the user requested, then register
276
         * now (setup won't fail at this point).  It's ok to just
277
         * call register again if previously .setup failed.
278
         */
279
        if (index == hvc_con_driver.index)
280
                register_console(&hvc_con_driver);
281
 
282
        return 0;
283
}
284
 
285
/* Wake the sleeping khvcd */
286
static void hvc_kick(void)
287
{
288
        hvc_kicked = 1;
289
        wake_up_process(hvc_task);
290
}
291
 
292
static int hvc_poll(struct hvc_struct *hp);
293
 
294
/*
295
 * NOTE: This API isn't used if the console adapter doesn't support interrupts.
296
 * In this case the console is poll driven.
297
 */
298
static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance)
299
{
300
        /* if hvc_poll request a repoll, then kick the hvcd thread */
301
        if (hvc_poll(dev_instance))
302
                hvc_kick();
303
        return IRQ_HANDLED;
304
}
305
 
306
static void hvc_unthrottle(struct tty_struct *tty)
307
{
308
        hvc_kick();
309
}
310
 
311
/*
312
 * The TTY interface won't be used until after the vio layer has exposed the vty
313
 * adapter to the kernel.
314
 */
315
static int hvc_open(struct tty_struct *tty, struct file * filp)
316
{
317
        struct hvc_struct *hp;
318
        unsigned long flags;
319
        int irq = 0;
320
        int rc = 0;
321
        struct kobject *kobjp;
322
 
323
        /* Auto increments kobject reference if found. */
324
        if (!(hp = hvc_get_by_index(tty->index)))
325
                return -ENODEV;
326
 
327
        spin_lock_irqsave(&hp->lock, flags);
328
        /* Check and then increment for fast path open. */
329
        if (hp->count++ > 0) {
330
                spin_unlock_irqrestore(&hp->lock, flags);
331
                hvc_kick();
332
                return 0;
333
        } /* else count == 0 */
334
 
335
        tty->driver_data = hp;
336
        tty->low_latency = 1; /* Makes flushes to ldisc synchronous. */
337
 
338
        hp->tty = tty;
339
        /* Save for request_irq outside of spin_lock. */
340
        irq = hp->irq;
341
        if (irq)
342
                hp->irq_requested = 1;
343
 
344
        kobjp = &hp->kobj;
345
 
346
        spin_unlock_irqrestore(&hp->lock, flags);
347
        /* check error, fallback to non-irq */
348
        if (irq)
349
                rc = request_irq(irq, hvc_handle_interrupt, IRQF_DISABLED, "hvc_console", hp);
350
 
351
        /*
352
         * If the request_irq() fails and we return an error.  The tty layer
353
         * will call hvc_close() after a failed open but we don't want to clean
354
         * up there so we'll clean up here and clear out the previously set
355
         * tty fields and return the kobject reference.
356
         */
357
        if (rc) {
358
                spin_lock_irqsave(&hp->lock, flags);
359
                hp->tty = NULL;
360
                hp->irq_requested = 0;
361
                spin_unlock_irqrestore(&hp->lock, flags);
362
                tty->driver_data = NULL;
363
                kobject_put(kobjp);
364
                printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
365
        }
366
        /* Force wakeup of the polling thread */
367
        hvc_kick();
368
 
369
        return rc;
370
}
371
 
372
static void hvc_close(struct tty_struct *tty, struct file * filp)
373
{
374
        struct hvc_struct *hp;
375
        struct kobject *kobjp;
376
        int irq = 0;
377
        unsigned long flags;
378
 
379
        if (tty_hung_up_p(filp))
380
                return;
381
 
382
        /*
383
         * No driver_data means that this close was issued after a failed
384
         * hvc_open by the tty layer's release_dev() function and we can just
385
         * exit cleanly because the kobject reference wasn't made.
386
         */
387
        if (!tty->driver_data)
388
                return;
389
 
390
        hp = tty->driver_data;
391
        spin_lock_irqsave(&hp->lock, flags);
392
 
393
        kobjp = &hp->kobj;
394
        if (--hp->count == 0) {
395
                if (hp->irq_requested)
396
                        irq = hp->irq;
397
                hp->irq_requested = 0;
398
 
399
                /* We are done with the tty pointer now. */
400
                hp->tty = NULL;
401
                spin_unlock_irqrestore(&hp->lock, flags);
402
 
403
                /*
404
                 * Chain calls chars_in_buffer() and returns immediately if
405
                 * there is no buffered data otherwise sleeps on a wait queue
406
                 * waking periodically to check chars_in_buffer().
407
                 */
408
                tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
409
 
410
                if (irq)
411
                        free_irq(irq, hp);
412
 
413
        } else {
414
                if (hp->count < 0)
415
                        printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
416
                                hp->vtermno, hp->count);
417
                spin_unlock_irqrestore(&hp->lock, flags);
418
        }
419
 
420
        kobject_put(kobjp);
421
}
422
 
423
static void hvc_hangup(struct tty_struct *tty)
424
{
425
        struct hvc_struct *hp = tty->driver_data;
426
        unsigned long flags;
427
        int irq = 0;
428
        int temp_open_count;
429
        struct kobject *kobjp;
430
 
431
        if (!hp)
432
                return;
433
 
434
        spin_lock_irqsave(&hp->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->count <= 0) {
442
                spin_unlock_irqrestore(&hp->lock, flags);
443
                return;
444
        }
445
 
446
        kobjp = &hp->kobj;
447
        temp_open_count = hp->count;
448
        hp->count = 0;
449
        hp->n_outbuf = 0;
450
        hp->tty = NULL;
451
        if (hp->irq_requested)
452
                /* Saved for use outside of spin_lock. */
453
                irq = hp->irq;
454
        hp->irq_requested = 0;
455
        spin_unlock_irqrestore(&hp->lock, flags);
456
        if (irq)
457
                free_irq(irq, hp);
458
        while(temp_open_count) {
459
                --temp_open_count;
460
                kobject_put(kobjp);
461
        }
462
}
463
 
464
/*
465
 * Push buffered characters whether they were just recently buffered or waiting
466
 * on a blocked hypervisor.  Call this function with hp->lock held.
467
 */
468
static void hvc_push(struct hvc_struct *hp)
469
{
470
        int n;
471
 
472
        n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
473
        if (n <= 0) {
474
                if (n == 0) {
475
                        hp->do_wakeup = 1;
476
                        return;
477
                }
478
                /* throw away output on error; this happens when
479
                   there is no session connected to the vterm. */
480
                hp->n_outbuf = 0;
481
        } else
482
                hp->n_outbuf -= n;
483
        if (hp->n_outbuf > 0)
484
                memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
485
        else
486
                hp->do_wakeup = 1;
487
}
488
 
489
static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
490
{
491
        struct hvc_struct *hp = tty->driver_data;
492
        unsigned long flags;
493
        int rsize, written = 0;
494
 
495
        /* This write was probably executed during a tty close. */
496
        if (!hp)
497
                return -EPIPE;
498
 
499
        if (hp->count <= 0)
500
                return -EIO;
501
 
502
        spin_lock_irqsave(&hp->lock, flags);
503
 
504
        /* Push pending writes */
505
        if (hp->n_outbuf > 0)
506
                hvc_push(hp);
507
 
508
        while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
509
                if (rsize > count)
510
                        rsize = count;
511
                memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
512
                count -= rsize;
513
                buf += rsize;
514
                hp->n_outbuf += rsize;
515
                written += rsize;
516
                hvc_push(hp);
517
        }
518
        spin_unlock_irqrestore(&hp->lock, flags);
519
 
520
        /*
521
         * Racy, but harmless, kick thread if there is still pending data.
522
         */
523
        if (hp->n_outbuf)
524
                hvc_kick();
525
 
526
        return written;
527
}
528
 
529
/*
530
 * This is actually a contract between the driver and the tty layer outlining
531
 * how much write room the driver can guarantee will be sent OR BUFFERED.  This
532
 * driver MUST honor the return value.
533
 */
534
static int hvc_write_room(struct tty_struct *tty)
535
{
536
        struct hvc_struct *hp = tty->driver_data;
537
 
538
        if (!hp)
539
                return -1;
540
 
541
        return hp->outbuf_size - hp->n_outbuf;
542
}
543
 
544
static int hvc_chars_in_buffer(struct tty_struct *tty)
545
{
546
        struct hvc_struct *hp = tty->driver_data;
547
 
548
        if (!hp)
549
                return -1;
550
        return hp->n_outbuf;
551
}
552
 
553
/*
554
 * timeout will vary between the MIN and MAX values defined here.  By default
555
 * and during console activity we will use a default MIN_TIMEOUT of 10.  When
556
 * the console is idle, we increase the timeout value on each pass through
557
 * msleep until we reach the max.  This may be noticeable as a brief (average
558
 * one second) delay on the console before the console responds to input when
559
 * there has been no input for some time.
560
 */
561
#define MIN_TIMEOUT             (10)
562
#define MAX_TIMEOUT             (2000)
563
static u32 timeout = MIN_TIMEOUT;
564
 
565
#define HVC_POLL_READ   0x00000001
566
#define HVC_POLL_WRITE  0x00000002
567
 
568
static int hvc_poll(struct hvc_struct *hp)
569
{
570
        struct tty_struct *tty;
571
        int i, n, poll_mask = 0;
572
        char buf[N_INBUF] __ALIGNED__;
573
        unsigned long flags;
574
        int read_total = 0;
575
 
576
        spin_lock_irqsave(&hp->lock, flags);
577
 
578
        /* Push pending writes */
579
        if (hp->n_outbuf > 0)
580
                hvc_push(hp);
581
 
582
        /* Reschedule us if still some write pending */
583
        if (hp->n_outbuf > 0)
584
                poll_mask |= HVC_POLL_WRITE;
585
 
586
        /* No tty attached, just skip */
587
        tty = hp->tty;
588
        if (tty == NULL)
589
                goto bail;
590
 
591
        /* Now check if we can get data (are we throttled ?) */
592
        if (test_bit(TTY_THROTTLED, &tty->flags))
593
                goto throttled;
594
 
595
        /* If we aren't interrupt driven and aren't throttled, we always
596
         * request a reschedule
597
         */
598
        if (hp->irq == 0)
599
                poll_mask |= HVC_POLL_READ;
600
 
601
        /* Read data if any */
602
        for (;;) {
603
                int count = tty_buffer_request_room(tty, N_INBUF);
604
 
605
                /* If flip is full, just reschedule a later read */
606
                if (count == 0) {
607
                        poll_mask |= HVC_POLL_READ;
608
                        break;
609
                }
610
 
611
                n = hp->ops->get_chars(hp->vtermno, buf, count);
612
                if (n <= 0) {
613
                        /* Hangup the tty when disconnected from host */
614
                        if (n == -EPIPE) {
615
                                spin_unlock_irqrestore(&hp->lock, flags);
616
                                tty_hangup(tty);
617
                                spin_lock_irqsave(&hp->lock, flags);
618
                        } else if ( n == -EAGAIN ) {
619
                                /*
620
                                 * Some back-ends can only ensure a certain min
621
                                 * num of bytes read, which may be > 'count'.
622
                                 * Let the tty clear the flip buff to make room.
623
                                 */
624
                                poll_mask |= HVC_POLL_READ;
625
                        }
626
                        break;
627
                }
628
                for (i = 0; i < n; ++i) {
629
#ifdef CONFIG_MAGIC_SYSRQ
630
                        if (hp->index == hvc_con_driver.index) {
631
                                /* Handle the SysRq Hack */
632
                                /* XXX should support a sequence */
633
                                if (buf[i] == '\x0f') { /* ^O */
634
                                        sysrq_pressed = 1;
635
                                        continue;
636
                                } else if (sysrq_pressed) {
637
                                        handle_sysrq(buf[i], tty);
638
                                        sysrq_pressed = 0;
639
                                        continue;
640
                                }
641
                        }
642
#endif /* CONFIG_MAGIC_SYSRQ */
643
                        tty_insert_flip_char(tty, buf[i], 0);
644
                }
645
 
646
                read_total += n;
647
        }
648
 throttled:
649
        /* Wakeup write queue if necessary */
650
        if (hp->do_wakeup) {
651
                hp->do_wakeup = 0;
652
                tty_wakeup(tty);
653
        }
654
 bail:
655
        spin_unlock_irqrestore(&hp->lock, flags);
656
 
657
        if (read_total) {
658
                /* Activity is occurring, so reset the polling backoff value to
659
                   a minimum for performance. */
660
                timeout = MIN_TIMEOUT;
661
 
662
                tty_flip_buffer_push(tty);
663
        }
664
 
665
        return poll_mask;
666
}
667
 
668
#if defined(CONFIG_XMON) && defined(CONFIG_SMP)
669
extern cpumask_t cpus_in_xmon;
670
#else
671
static const cpumask_t cpus_in_xmon = CPU_MASK_NONE;
672
#endif
673
 
674
/*
675
 * This kthread is either polling or interrupt driven.  This is determined by
676
 * calling hvc_poll() who determines whether a console adapter support
677
 * interrupts.
678
 */
679
static int khvcd(void *unused)
680
{
681
        int poll_mask;
682
        struct hvc_struct *hp;
683
 
684
        set_freezable();
685
        __set_current_state(TASK_RUNNING);
686
        do {
687
                poll_mask = 0;
688
                hvc_kicked = 0;
689
                try_to_freeze();
690
                wmb();
691
                if (cpus_empty(cpus_in_xmon)) {
692
                        spin_lock(&hvc_structs_lock);
693
                        list_for_each_entry(hp, &hvc_structs, next) {
694
                                poll_mask |= hvc_poll(hp);
695
                        }
696
                        spin_unlock(&hvc_structs_lock);
697
                } else
698
                        poll_mask |= HVC_POLL_READ;
699
                if (hvc_kicked)
700
                        continue;
701
                if (poll_mask & HVC_POLL_WRITE) {
702
                        yield();
703
                        continue;
704
                }
705
                set_current_state(TASK_INTERRUPTIBLE);
706
                if (!hvc_kicked) {
707
                        if (poll_mask == 0)
708
                                schedule();
709
                        else {
710
                                if (timeout < MAX_TIMEOUT)
711
                                        timeout += (timeout >> 6) + 1;
712
 
713
                                msleep_interruptible(timeout);
714
                        }
715
                }
716
                __set_current_state(TASK_RUNNING);
717
        } while (!kthread_should_stop());
718
 
719
        return 0;
720
}
721
 
722
static const struct tty_operations hvc_ops = {
723
        .open = hvc_open,
724
        .close = hvc_close,
725
        .write = hvc_write,
726
        .hangup = hvc_hangup,
727
        .unthrottle = hvc_unthrottle,
728
        .write_room = hvc_write_room,
729
        .chars_in_buffer = hvc_chars_in_buffer,
730
};
731
 
732
/* callback when the kboject ref count reaches zero. */
733
static void destroy_hvc_struct(struct kobject *kobj)
734
{
735
        struct hvc_struct *hp = container_of(kobj, struct hvc_struct, kobj);
736
        unsigned long flags;
737
 
738
        spin_lock(&hvc_structs_lock);
739
 
740
        spin_lock_irqsave(&hp->lock, flags);
741
        list_del(&(hp->next));
742
        spin_unlock_irqrestore(&hp->lock, flags);
743
 
744
        spin_unlock(&hvc_structs_lock);
745
 
746
        kfree(hp);
747
}
748
 
749
static struct kobj_type hvc_kobj_type = {
750
        .release = destroy_hvc_struct,
751
};
752
 
753
struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int irq,
754
                                        struct hv_ops *ops, int outbuf_size)
755
{
756
        struct hvc_struct *hp;
757
        int i;
758
 
759
        /* We wait until a driver actually comes along */
760
        if (!hvc_driver) {
761
                int err = hvc_init();
762
                if (err)
763
                        return ERR_PTR(err);
764
        }
765
 
766
        hp = kmalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
767
                        GFP_KERNEL);
768
        if (!hp)
769
                return ERR_PTR(-ENOMEM);
770
 
771
        memset(hp, 0x00, sizeof(*hp));
772
 
773
        hp->vtermno = vtermno;
774
        hp->irq = irq;
775
        hp->ops = ops;
776
        hp->outbuf_size = outbuf_size;
777
        hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
778
 
779
        kobject_init(&hp->kobj);
780
        hp->kobj.ktype = &hvc_kobj_type;
781
 
782
        spin_lock_init(&hp->lock);
783
        spin_lock(&hvc_structs_lock);
784
 
785
        /*
786
         * find index to use:
787
         * see if this vterm id matches one registered for console.
788
         */
789
        for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
790
                if (vtermnos[i] == hp->vtermno &&
791
                    cons_ops[i] == hp->ops)
792
                        break;
793
 
794
        /* no matching slot, just use a counter */
795
        if (i >= MAX_NR_HVC_CONSOLES)
796
                i = ++last_hvc;
797
 
798
        hp->index = i;
799
 
800
        list_add_tail(&(hp->next), &hvc_structs);
801
        spin_unlock(&hvc_structs_lock);
802
 
803
        return hp;
804
}
805
 
806
int __devexit hvc_remove(struct hvc_struct *hp)
807
{
808
        unsigned long flags;
809
        struct kobject *kobjp;
810
        struct tty_struct *tty;
811
 
812
        spin_lock_irqsave(&hp->lock, flags);
813
        tty = hp->tty;
814
        kobjp = &hp->kobj;
815
 
816
        if (hp->index < MAX_NR_HVC_CONSOLES)
817
                vtermnos[hp->index] = -1;
818
 
819
        /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
820
 
821
        spin_unlock_irqrestore(&hp->lock, flags);
822
 
823
        /*
824
         * We 'put' the instance that was grabbed when the kobject instance
825
         * was initialized using kobject_init().  Let the last holder of this
826
         * kobject cause it to be removed, which will probably be the tty_hangup
827
         * below.
828
         */
829
        kobject_put(kobjp);
830
 
831
        /*
832
         * This function call will auto chain call hvc_hangup.  The tty should
833
         * always be valid at this time unless a simultaneous tty close already
834
         * cleaned up the hvc_struct.
835
         */
836
        if (tty)
837
                tty_hangup(tty);
838
        return 0;
839
}
840
 
841
/* Driver initialization: called as soon as someone uses hvc_alloc(). */
842
static int hvc_init(void)
843
{
844
        struct tty_driver *drv;
845
        int err;
846
 
847
        /* We need more than hvc_count adapters due to hotplug additions. */
848
        drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
849
        if (!drv) {
850
                err = -ENOMEM;
851
                goto out;
852
        }
853
 
854
        drv->owner = THIS_MODULE;
855
        drv->driver_name = "hvc";
856
        drv->name = "hvc";
857
        drv->major = HVC_MAJOR;
858
        drv->minor_start = HVC_MINOR;
859
        drv->type = TTY_DRIVER_TYPE_SYSTEM;
860
        drv->init_termios = tty_std_termios;
861
        drv->flags = TTY_DRIVER_REAL_RAW;
862
        tty_set_operations(drv, &hvc_ops);
863
 
864
        /* Always start the kthread because there can be hotplug vty adapters
865
         * added later. */
866
        hvc_task = kthread_run(khvcd, NULL, "khvcd");
867
        if (IS_ERR(hvc_task)) {
868
                printk(KERN_ERR "Couldn't create kthread for console.\n");
869
                err = PTR_ERR(hvc_task);
870
                goto put_tty;
871
        }
872
 
873
        err = tty_register_driver(drv);
874
        if (err) {
875
                printk(KERN_ERR "Couldn't register hvc console driver\n");
876
                goto stop_thread;
877
        }
878
 
879
        /* FIXME: This mb() seems completely random.  Remove it. */
880
        mb();
881
        hvc_driver = drv;
882
        return 0;
883
 
884
put_tty:
885
        put_tty_driver(hvc_driver);
886
stop_thread:
887
        kthread_stop(hvc_task);
888
        hvc_task = NULL;
889
out:
890
        return err;
891
}
892
 
893
/* This isn't particularly necessary due to this being a console driver
894
 * but it is nice to be thorough.
895
 */
896
static void __exit hvc_exit(void)
897
{
898
        if (hvc_driver) {
899
                kthread_stop(hvc_task);
900
 
901
                tty_unregister_driver(hvc_driver);
902
                /* return tty_struct instances allocated in hvc_init(). */
903
                put_tty_driver(hvc_driver);
904
                unregister_console(&hvc_con_driver);
905
        }
906
}
907
module_exit(hvc_exit);

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