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Merge tag 'acpi-fix-4.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael...
[linux.git] / drivers / tty / hvc / hvc_console.c
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (C) 2001 Anton Blanchard <[email protected]>, IBM
4  * Copyright (C) 2001 Paul Mackerras <[email protected]>, IBM
5  * Copyright (C) 2004 Benjamin Herrenschmidt <[email protected]>, IBM Corp.
6  * Copyright (C) 2004 IBM Corporation
7  *
8  * Additional Author(s):
9  *  Ryan S. Arnold <[email protected]>
10  */
11
12 #include <linux/console.h>
13 #include <linux/cpumask.h>
14 #include <linux/init.h>
15 #include <linux/kbd_kern.h>
16 #include <linux/kernel.h>
17 #include <linux/kthread.h>
18 #include <linux/list.h>
19 #include <linux/major.h>
20 #include <linux/atomic.h>
21 #include <linux/sysrq.h>
22 #include <linux/tty.h>
23 #include <linux/tty_flip.h>
24 #include <linux/sched.h>
25 #include <linux/spinlock.h>
26 #include <linux/delay.h>
27 #include <linux/freezer.h>
28 #include <linux/slab.h>
29 #include <linux/serial_core.h>
30
31 #include <linux/uaccess.h>
32
33 #include "hvc_console.h"
34
35 #define HVC_MAJOR       229
36 #define HVC_MINOR       0
37
38 /*
39  * Wait this long per iteration while trying to push buffered data to the
40  * hypervisor before allowing the tty to complete a close operation.
41  */
42 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
43
44 /*
45  * These sizes are most efficient for vio, because they are the
46  * native transfer size. We could make them selectable in the
47  * future to better deal with backends that want other buffer sizes.
48  */
49 #define N_OUTBUF        16
50 #define N_INBUF         16
51
52 #define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
53
54 static struct tty_driver *hvc_driver;
55 static struct task_struct *hvc_task;
56
57 /* Picks up late kicks after list walk but before schedule() */
58 static int hvc_kicked;
59
60 /* hvc_init is triggered from hvc_alloc, i.e. only when actually used */
61 static atomic_t hvc_needs_init __read_mostly = ATOMIC_INIT(-1);
62
63 static int hvc_init(void);
64
65 #ifdef CONFIG_MAGIC_SYSRQ
66 static int sysrq_pressed;
67 #endif
68
69 /* dynamic list of hvc_struct instances */
70 static LIST_HEAD(hvc_structs);
71
72 /*
73  * Protect the list of hvc_struct instances from inserts and removals during
74  * list traversal.
75  */
76 static DEFINE_SPINLOCK(hvc_structs_lock);
77
78 /*
79  * This value is used to assign a tty->index value to a hvc_struct based
80  * upon order of exposure via hvc_probe(), when we can not match it to
81  * a console candidate registered with hvc_instantiate().
82  */
83 static int last_hvc = -1;
84
85 /*
86  * Do not call this function with either the hvc_structs_lock or the hvc_struct
87  * lock held.  If successful, this function increments the kref reference
88  * count against the target hvc_struct so it should be released when finished.
89  */
90 static struct hvc_struct *hvc_get_by_index(int index)
91 {
92         struct hvc_struct *hp;
93         unsigned long flags;
94
95         spin_lock(&hvc_structs_lock);
96
97         list_for_each_entry(hp, &hvc_structs, next) {
98                 spin_lock_irqsave(&hp->lock, flags);
99                 if (hp->index == index) {
100                         tty_port_get(&hp->port);
101                         spin_unlock_irqrestore(&hp->lock, flags);
102                         spin_unlock(&hvc_structs_lock);
103                         return hp;
104                 }
105                 spin_unlock_irqrestore(&hp->lock, flags);
106         }
107         hp = NULL;
108
109         spin_unlock(&hvc_structs_lock);
110         return hp;
111 }
112
113
114 /*
115  * Initial console vtermnos for console API usage prior to full console
116  * initialization.  Any vty adapter outside this range will not have usable
117  * console interfaces but can still be used as a tty device.  This has to be
118  * static because kmalloc will not work during early console init.
119  */
120 static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
121 static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
122         {[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
123
124 /*
125  * Console APIs, NOT TTY.  These APIs are available immediately when
126  * hvc_console_setup() finds adapters.
127  */
128
129 static void hvc_console_print(struct console *co, const char *b,
130                               unsigned count)
131 {
132         char c[N_OUTBUF] __ALIGNED__;
133         unsigned i = 0, n = 0;
134         int r, donecr = 0, index = co->index;
135
136         /* Console access attempt outside of acceptable console range. */
137         if (index >= MAX_NR_HVC_CONSOLES)
138                 return;
139
140         /* This console adapter was removed so it is not usable. */
141         if (vtermnos[index] == -1)
142                 return;
143
144         while (count > 0 || i > 0) {
145                 if (count > 0 && i < sizeof(c)) {
146                         if (b[n] == '\n' && !donecr) {
147                                 c[i++] = '\r';
148                                 donecr = 1;
149                         } else {
150                                 c[i++] = b[n++];
151                                 donecr = 0;
152                                 --count;
153                         }
154                 } else {
155                         r = cons_ops[index]->put_chars(vtermnos[index], c, i);
156                         if (r <= 0) {
157                                 /* throw away characters on error
158                                  * but spin in case of -EAGAIN */
159                                 if (r != -EAGAIN)
160                                         i = 0;
161                         } else if (r > 0) {
162                                 i -= r;
163                                 if (i > 0)
164                                         memmove(c, c+r, i);
165                         }
166                 }
167         }
168 }
169
170 static struct tty_driver *hvc_console_device(struct console *c, int *index)
171 {
172         if (vtermnos[c->index] == -1)
173                 return NULL;
174
175         *index = c->index;
176         return hvc_driver;
177 }
178
179 static int hvc_console_setup(struct console *co, char *options)
180 {       
181         if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
182                 return -ENODEV;
183
184         if (vtermnos[co->index] == -1)
185                 return -ENODEV;
186
187         return 0;
188 }
189
190 static struct console hvc_console = {
191         .name           = "hvc",
192         .write          = hvc_console_print,
193         .device         = hvc_console_device,
194         .setup          = hvc_console_setup,
195         .flags          = CON_PRINTBUFFER,
196         .index          = -1,
197 };
198
199 /*
200  * Early console initialization.  Precedes driver initialization.
201  *
202  * (1) we are first, and the user specified another driver
203  * -- index will remain -1
204  * (2) we are first and the user specified no driver
205  * -- index will be set to 0, then we will fail setup.
206  * (3)  we are first and the user specified our driver
207  * -- index will be set to user specified driver, and we will fail
208  * (4) we are after driver, and this initcall will register us
209  * -- if the user didn't specify a driver then the console will match
210  *
211  * Note that for cases 2 and 3, we will match later when the io driver
212  * calls hvc_instantiate() and call register again.
213  */
214 static int __init hvc_console_init(void)
215 {
216         register_console(&hvc_console);
217         return 0;
218 }
219 console_initcall(hvc_console_init);
220
221 /* callback when the kboject ref count reaches zero. */
222 static void hvc_port_destruct(struct tty_port *port)
223 {
224         struct hvc_struct *hp = container_of(port, struct hvc_struct, port);
225         unsigned long flags;
226
227         spin_lock(&hvc_structs_lock);
228
229         spin_lock_irqsave(&hp->lock, flags);
230         list_del(&(hp->next));
231         spin_unlock_irqrestore(&hp->lock, flags);
232
233         spin_unlock(&hvc_structs_lock);
234
235         kfree(hp);
236 }
237
238 static void hvc_check_console(int index)
239 {
240         /* Already enabled, bail out */
241         if (hvc_console.flags & CON_ENABLED)
242                 return;
243
244         /* If this index is what the user requested, then register
245          * now (setup won't fail at this point).  It's ok to just
246          * call register again if previously .setup failed.
247          */
248         if (index == hvc_console.index)
249                 register_console(&hvc_console);
250 }
251
252 /*
253  * hvc_instantiate() is an early console discovery method which locates
254  * consoles * prior to the vio subsystem discovering them.  Hotplugged
255  * vty adapters do NOT get an hvc_instantiate() callback since they
256  * appear after early console init.
257  */
258 int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
259 {
260         struct hvc_struct *hp;
261
262         if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
263                 return -1;
264
265         if (vtermnos[index] != -1)
266                 return -1;
267
268         /* make sure no no tty has been registered in this index */
269         hp = hvc_get_by_index(index);
270         if (hp) {
271                 tty_port_put(&hp->port);
272                 return -1;
273         }
274
275         vtermnos[index] = vtermno;
276         cons_ops[index] = ops;
277
278         /* reserve all indices up to and including this index */
279         if (last_hvc < index)
280                 last_hvc = index;
281
282         /* check if we need to re-register the kernel console */
283         hvc_check_console(index);
284
285         return 0;
286 }
287 EXPORT_SYMBOL_GPL(hvc_instantiate);
288
289 /* Wake the sleeping khvcd */
290 void hvc_kick(void)
291 {
292         hvc_kicked = 1;
293         wake_up_process(hvc_task);
294 }
295 EXPORT_SYMBOL_GPL(hvc_kick);
296
297 static void hvc_unthrottle(struct tty_struct *tty)
298 {
299         hvc_kick();
300 }
301
302 static int hvc_install(struct tty_driver *driver, struct tty_struct *tty)
303 {
304         struct hvc_struct *hp;
305         int rc;
306
307         /* Auto increments kref reference if found. */
308         hp = hvc_get_by_index(tty->index);
309         if (!hp)
310                 return -ENODEV;
311
312         tty->driver_data = hp;
313
314         rc = tty_port_install(&hp->port, driver, tty);
315         if (rc)
316                 tty_port_put(&hp->port);
317         return rc;
318 }
319
320 /*
321  * The TTY interface won't be used until after the vio layer has exposed the vty
322  * adapter to the kernel.
323  */
324 static int hvc_open(struct tty_struct *tty, struct file * filp)
325 {
326         struct hvc_struct *hp = tty->driver_data;
327         unsigned long flags;
328         int rc = 0;
329
330         spin_lock_irqsave(&hp->port.lock, flags);
331         /* Check and then increment for fast path open. */
332         if (hp->port.count++ > 0) {
333                 spin_unlock_irqrestore(&hp->port.lock, flags);
334                 hvc_kick();
335                 return 0;
336         } /* else count == 0 */
337         spin_unlock_irqrestore(&hp->port.lock, flags);
338
339         tty_port_tty_set(&hp->port, tty);
340
341         if (hp->ops->notifier_add)
342                 rc = hp->ops->notifier_add(hp, hp->data);
343
344         /*
345          * If the notifier fails we return an error.  The tty layer
346          * will call hvc_close() after a failed open but we don't want to clean
347          * up there so we'll clean up here and clear out the previously set
348          * tty fields and return the kref reference.
349          */
350         if (rc) {
351                 tty_port_tty_set(&hp->port, NULL);
352                 tty->driver_data = NULL;
353                 tty_port_put(&hp->port);
354                 printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
355         } else
356                 /* We are ready... raise DTR/RTS */
357                 if (C_BAUD(tty))
358                         if (hp->ops->dtr_rts)
359                                 hp->ops->dtr_rts(hp, 1);
360
361         /* Force wakeup of the polling thread */
362         hvc_kick();
363
364         return rc;
365 }
366
367 static void hvc_close(struct tty_struct *tty, struct file * filp)
368 {
369         struct hvc_struct *hp;
370         unsigned long flags;
371
372         if (tty_hung_up_p(filp))
373                 return;
374
375         /*
376          * No driver_data means that this close was issued after a failed
377          * hvc_open by the tty layer's release_dev() function and we can just
378          * exit cleanly because the kref reference wasn't made.
379          */
380         if (!tty->driver_data)
381                 return;
382
383         hp = tty->driver_data;
384
385         spin_lock_irqsave(&hp->port.lock, flags);
386
387         if (--hp->port.count == 0) {
388                 spin_unlock_irqrestore(&hp->port.lock, flags);
389                 /* We are done with the tty pointer now. */
390                 tty_port_tty_set(&hp->port, NULL);
391
392                 if (C_HUPCL(tty))
393                         if (hp->ops->dtr_rts)
394                                 hp->ops->dtr_rts(hp, 0);
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(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
416 static 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
423 static 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  */
460 static 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
483 static 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  */
533 static 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  */
559 static 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
569 static 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)
588 static u32 timeout = MIN_TIMEOUT;
589
590 #define HVC_POLL_READ   0x00000001
591 #define HVC_POLL_WRITE  0x00000002
592
593 int 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 (tty_throttled(tty))
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 }
700 EXPORT_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  */
712 void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
713 {
714         hp->ws = ws;
715         schedule_work(&hp->tty_resize);
716 }
717 EXPORT_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  */
724 static 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                                 unsigned long j_timeout;
751
752                                 if (timeout < MAX_TIMEOUT)
753                                         timeout += (timeout >> 6) + 1;
754
755                                 /*
756                                  * We don't use msleep_interruptible otherwise
757                                  * "kick" will fail to wake us up
758                                  */
759                                 j_timeout = msecs_to_jiffies(timeout) + 1;
760                                 schedule_timeout_interruptible(j_timeout);
761                         }
762                 }
763                 __set_current_state(TASK_RUNNING);
764         } while (!kthread_should_stop());
765
766         return 0;
767 }
768
769 static int hvc_tiocmget(struct tty_struct *tty)
770 {
771         struct hvc_struct *hp = tty->driver_data;
772
773         if (!hp || !hp->ops->tiocmget)
774                 return -EINVAL;
775         return hp->ops->tiocmget(hp);
776 }
777
778 static int hvc_tiocmset(struct tty_struct *tty,
779                         unsigned int set, unsigned int clear)
780 {
781         struct hvc_struct *hp = tty->driver_data;
782
783         if (!hp || !hp->ops->tiocmset)
784                 return -EINVAL;
785         return hp->ops->tiocmset(hp, set, clear);
786 }
787
788 #ifdef CONFIG_CONSOLE_POLL
789 static int hvc_poll_init(struct tty_driver *driver, int line, char *options)
790 {
791         return 0;
792 }
793
794 static int hvc_poll_get_char(struct tty_driver *driver, int line)
795 {
796         struct tty_struct *tty = driver->ttys[0];
797         struct hvc_struct *hp = tty->driver_data;
798         int n;
799         char ch;
800
801         n = hp->ops->get_chars(hp->vtermno, &ch, 1);
802
803         if (n <= 0)
804                 return NO_POLL_CHAR;
805
806         return ch;
807 }
808
809 static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
810 {
811         struct tty_struct *tty = driver->ttys[0];
812         struct hvc_struct *hp = tty->driver_data;
813         int n;
814
815         do {
816                 n = hp->ops->put_chars(hp->vtermno, &ch, 1);
817         } while (n <= 0);
818 }
819 #endif
820
821 static const struct tty_operations hvc_ops = {
822         .install = hvc_install,
823         .open = hvc_open,
824         .close = hvc_close,
825         .cleanup = hvc_cleanup,
826         .write = hvc_write,
827         .hangup = hvc_hangup,
828         .unthrottle = hvc_unthrottle,
829         .write_room = hvc_write_room,
830         .chars_in_buffer = hvc_chars_in_buffer,
831         .tiocmget = hvc_tiocmget,
832         .tiocmset = hvc_tiocmset,
833 #ifdef CONFIG_CONSOLE_POLL
834         .poll_init = hvc_poll_init,
835         .poll_get_char = hvc_poll_get_char,
836         .poll_put_char = hvc_poll_put_char,
837 #endif
838 };
839
840 static const struct tty_port_operations hvc_port_ops = {
841         .destruct = hvc_port_destruct,
842 };
843
844 struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
845                              const struct hv_ops *ops,
846                              int outbuf_size)
847 {
848         struct hvc_struct *hp;
849         int i;
850
851         /* We wait until a driver actually comes along */
852         if (atomic_inc_not_zero(&hvc_needs_init)) {
853                 int err = hvc_init();
854                 if (err)
855                         return ERR_PTR(err);
856         }
857
858         hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
859                         GFP_KERNEL);
860         if (!hp)
861                 return ERR_PTR(-ENOMEM);
862
863         hp->vtermno = vtermno;
864         hp->data = data;
865         hp->ops = ops;
866         hp->outbuf_size = outbuf_size;
867         hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
868
869         tty_port_init(&hp->port);
870         hp->port.ops = &hvc_port_ops;
871
872         INIT_WORK(&hp->tty_resize, hvc_set_winsz);
873         spin_lock_init(&hp->lock);
874         spin_lock(&hvc_structs_lock);
875
876         /*
877          * find index to use:
878          * see if this vterm id matches one registered for console.
879          */
880         for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
881                 if (vtermnos[i] == hp->vtermno &&
882                     cons_ops[i] == hp->ops)
883                         break;
884
885         /* no matching slot, just use a counter */
886         if (i >= MAX_NR_HVC_CONSOLES)
887                 i = ++last_hvc;
888
889         hp->index = i;
890         cons_ops[i] = ops;
891         vtermnos[i] = vtermno;
892
893         list_add_tail(&(hp->next), &hvc_structs);
894         spin_unlock(&hvc_structs_lock);
895
896         /* check if we need to re-register the kernel console */
897         hvc_check_console(i);
898
899         return hp;
900 }
901 EXPORT_SYMBOL_GPL(hvc_alloc);
902
903 int hvc_remove(struct hvc_struct *hp)
904 {
905         unsigned long flags;
906         struct tty_struct *tty;
907
908         tty = tty_port_tty_get(&hp->port);
909
910         console_lock();
911         spin_lock_irqsave(&hp->lock, flags);
912         if (hp->index < MAX_NR_HVC_CONSOLES) {
913                 vtermnos[hp->index] = -1;
914                 cons_ops[hp->index] = NULL;
915         }
916
917         /* Don't whack hp->irq because tty_hangup() will need to free the irq. */
918
919         spin_unlock_irqrestore(&hp->lock, flags);
920         console_unlock();
921
922         /*
923          * We 'put' the instance that was grabbed when the kref instance
924          * was initialized using kref_init().  Let the last holder of this
925          * kref cause it to be removed, which will probably be the tty_vhangup
926          * below.
927          */
928         tty_port_put(&hp->port);
929
930         /*
931          * This function call will auto chain call hvc_hangup.
932          */
933         if (tty) {
934                 tty_vhangup(tty);
935                 tty_kref_put(tty);
936         }
937         return 0;
938 }
939 EXPORT_SYMBOL_GPL(hvc_remove);
940
941 /* Driver initialization: called as soon as someone uses hvc_alloc(). */
942 static int hvc_init(void)
943 {
944         struct tty_driver *drv;
945         int err;
946
947         /* We need more than hvc_count adapters due to hotplug additions. */
948         drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
949         if (!drv) {
950                 err = -ENOMEM;
951                 goto out;
952         }
953
954         drv->driver_name = "hvc";
955         drv->name = "hvc";
956         drv->major = HVC_MAJOR;
957         drv->minor_start = HVC_MINOR;
958         drv->type = TTY_DRIVER_TYPE_SYSTEM;
959         drv->init_termios = tty_std_termios;
960         drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
961         tty_set_operations(drv, &hvc_ops);
962
963         /* Always start the kthread because there can be hotplug vty adapters
964          * added later. */
965         hvc_task = kthread_run(khvcd, NULL, "khvcd");
966         if (IS_ERR(hvc_task)) {
967                 printk(KERN_ERR "Couldn't create kthread for console.\n");
968                 err = PTR_ERR(hvc_task);
969                 goto put_tty;
970         }
971
972         err = tty_register_driver(drv);
973         if (err) {
974                 printk(KERN_ERR "Couldn't register hvc console driver\n");
975                 goto stop_thread;
976         }
977
978         /*
979          * Make sure tty is fully registered before allowing it to be
980          * found by hvc_console_device.
981          */
982         smp_mb();
983         hvc_driver = drv;
984         return 0;
985
986 stop_thread:
987         kthread_stop(hvc_task);
988         hvc_task = NULL;
989 put_tty:
990         put_tty_driver(drv);
991 out:
992         return err;
993 }
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