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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Tty port functions
4 */
5
6#include <linux/types.h>
7#include <linux/errno.h>
8#include <linux/tty.h>
9#include <linux/tty_driver.h>
10#include <linux/tty_flip.h>
11#include <linux/serial.h>
12#include <linux/timer.h>
13#include <linux/string.h>
14#include <linux/slab.h>
15#include <linux/sched/signal.h>
16#include <linux/wait.h>
17#include <linux/bitops.h>
18#include <linux/delay.h>
19#include <linux/module.h>
20#include <linux/serdev.h>
21#include "tty.h"
22
23static size_t tty_port_default_receive_buf(struct tty_port *port, const u8 *p,
24 const u8 *f, size_t count)
25{
26 struct tty_struct *tty;
27 struct tty_ldisc *ld;
28
29 tty = READ_ONCE(port->itty);
30 if (!tty)
31 return 0;
32
33 ld = tty_ldisc_ref(tty);
34 if (!ld)
35 return 0;
36
37 count = tty_ldisc_receive_buf(ld, p, f, count);
38
39 tty_ldisc_deref(ld);
40
41 return count;
42}
43
44static void tty_port_default_lookahead_buf(struct tty_port *port, const u8 *p,
45 const u8 *f, size_t count)
46{
47 struct tty_struct *tty;
48 struct tty_ldisc *ld;
49
50 tty = READ_ONCE(port->itty);
51 if (!tty)
52 return;
53
54 ld = tty_ldisc_ref(tty);
55 if (!ld)
56 return;
57
58 if (ld->ops->lookahead_buf)
59 ld->ops->lookahead_buf(ld->tty, p, f, count);
60
61 tty_ldisc_deref(ld);
62}
63
64static void tty_port_default_wakeup(struct tty_port *port)
65{
66 struct tty_struct *tty = tty_port_tty_get(port);
67
68 if (tty) {
69 tty_wakeup(tty);
70 tty_kref_put(tty);
71 }
72}
73
74const struct tty_port_client_operations tty_port_default_client_ops = {
75 .receive_buf = tty_port_default_receive_buf,
76 .lookahead_buf = tty_port_default_lookahead_buf,
77 .write_wakeup = tty_port_default_wakeup,
78};
79EXPORT_SYMBOL_GPL(tty_port_default_client_ops);
80
81/**
82 * tty_port_init - initialize tty_port
83 * @port: tty_port to initialize
84 *
85 * Initializes the state of struct tty_port. When a port was initialized using
86 * this function, one has to destroy the port by tty_port_destroy(). Either
87 * indirectly by using &tty_port refcounting (tty_port_put()) or directly if
88 * refcounting is not used.
89 */
90void tty_port_init(struct tty_port *port)
91{
92 memset(port, 0, sizeof(*port));
93 tty_buffer_init(port);
94 init_waitqueue_head(&port->open_wait);
95 init_waitqueue_head(&port->delta_msr_wait);
96 mutex_init(&port->mutex);
97 mutex_init(&port->buf_mutex);
98 spin_lock_init(&port->lock);
99 port->close_delay = (50 * HZ) / 100;
100 port->closing_wait = (3000 * HZ) / 100;
101 port->client_ops = &tty_port_default_client_ops;
102 kref_init(&port->kref);
103}
104EXPORT_SYMBOL(tty_port_init);
105
106/**
107 * tty_port_link_device - link tty and tty_port
108 * @port: tty_port of the device
109 * @driver: tty_driver for this device
110 * @index: index of the tty
111 *
112 * Provide the tty layer with a link from a tty (specified by @index) to a
113 * tty_port (@port). Use this only if neither tty_port_register_device() nor
114 * tty_port_install() is used in the driver. If used, this has to be called
115 * before tty_register_driver().
116 */
117void tty_port_link_device(struct tty_port *port,
118 struct tty_driver *driver, unsigned index)
119{
120 if (WARN_ON(index >= driver->num))
121 return;
122 driver->ports[index] = port;
123}
124EXPORT_SYMBOL_GPL(tty_port_link_device);
125
126/**
127 * tty_port_register_device - register tty device
128 * @port: tty_port of the device
129 * @driver: tty_driver for this device
130 * @index: index of the tty
131 * @device: parent if exists, otherwise NULL
132 *
133 * It is the same as tty_register_device() except the provided @port is linked
134 * to a concrete tty specified by @index. Use this or tty_port_install() (or
135 * both). Call tty_port_link_device() as a last resort.
136 */
137struct device *tty_port_register_device(struct tty_port *port,
138 struct tty_driver *driver, unsigned index,
139 struct device *device)
140{
141 return tty_port_register_device_attr(port, driver, index, device, NULL, NULL);
142}
143EXPORT_SYMBOL_GPL(tty_port_register_device);
144
145/**
146 * tty_port_register_device_attr - register tty device
147 * @port: tty_port of the device
148 * @driver: tty_driver for this device
149 * @index: index of the tty
150 * @device: parent if exists, otherwise NULL
151 * @drvdata: Driver data to be set to device.
152 * @attr_grp: Attribute group to be set on device.
153 *
154 * It is the same as tty_register_device_attr() except the provided @port is
155 * linked to a concrete tty specified by @index. Use this or tty_port_install()
156 * (or both). Call tty_port_link_device() as a last resort.
157 */
158struct device *tty_port_register_device_attr(struct tty_port *port,
159 struct tty_driver *driver, unsigned index,
160 struct device *device, void *drvdata,
161 const struct attribute_group **attr_grp)
162{
163 tty_port_link_device(port, driver, index);
164 return tty_register_device_attr(driver, index, device, drvdata,
165 attr_grp);
166}
167EXPORT_SYMBOL_GPL(tty_port_register_device_attr);
168
169/**
170 * tty_port_register_device_attr_serdev - register tty or serdev device
171 * @port: tty_port of the device
172 * @driver: tty_driver for this device
173 * @index: index of the tty
174 * @host: serial port hardware device
175 * @parent: parent if exists, otherwise NULL
176 * @drvdata: driver data for the device
177 * @attr_grp: attribute group for the device
178 *
179 * Register a serdev or tty device depending on if the parent device has any
180 * defined serdev clients or not.
181 */
182struct device *tty_port_register_device_attr_serdev(struct tty_port *port,
183 struct tty_driver *driver, unsigned index,
184 struct device *host, struct device *parent, void *drvdata,
185 const struct attribute_group **attr_grp)
186{
187 struct device *dev;
188
189 tty_port_link_device(port, driver, index);
190
191 dev = serdev_tty_port_register(port, host, parent, driver, index);
192 if (PTR_ERR(dev) != -ENODEV) {
193 /* Skip creating cdev if we registered a serdev device */
194 return dev;
195 }
196
197 return tty_register_device_attr(driver, index, parent, drvdata,
198 attr_grp);
199}
200EXPORT_SYMBOL_GPL(tty_port_register_device_attr_serdev);
201
202/**
203 * tty_port_register_device_serdev - register tty or serdev device
204 * @port: tty_port of the device
205 * @driver: tty_driver for this device
206 * @index: index of the tty
207 * @host: serial port hardware controller device
208 * @parent: parent if exists, otherwise NULL
209 *
210 * Register a serdev or tty device depending on if the parent device has any
211 * defined serdev clients or not.
212 */
213struct device *tty_port_register_device_serdev(struct tty_port *port,
214 struct tty_driver *driver, unsigned index,
215 struct device *host, struct device *parent)
216{
217 return tty_port_register_device_attr_serdev(port, driver, index,
218 host, parent, NULL, NULL);
219}
220EXPORT_SYMBOL_GPL(tty_port_register_device_serdev);
221
222/**
223 * tty_port_unregister_device - deregister a tty or serdev device
224 * @port: tty_port of the device
225 * @driver: tty_driver for this device
226 * @index: index of the tty
227 *
228 * If a tty or serdev device is registered with a call to
229 * tty_port_register_device_serdev() then this function must be called when
230 * the device is gone.
231 */
232void tty_port_unregister_device(struct tty_port *port,
233 struct tty_driver *driver, unsigned index)
234{
235 int ret;
236
237 ret = serdev_tty_port_unregister(port);
238 if (ret == 0)
239 return;
240
241 tty_unregister_device(driver, index);
242}
243EXPORT_SYMBOL_GPL(tty_port_unregister_device);
244
245int tty_port_alloc_xmit_buf(struct tty_port *port)
246{
247 /* We may sleep in get_zeroed_page() */
248 mutex_lock(&port->buf_mutex);
249 if (port->xmit_buf == NULL) {
250 port->xmit_buf = (u8 *)get_zeroed_page(GFP_KERNEL);
251 if (port->xmit_buf)
252 kfifo_init(&port->xmit_fifo, port->xmit_buf, PAGE_SIZE);
253 }
254 mutex_unlock(&port->buf_mutex);
255 if (port->xmit_buf == NULL)
256 return -ENOMEM;
257 return 0;
258}
259EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
260
261void tty_port_free_xmit_buf(struct tty_port *port)
262{
263 mutex_lock(&port->buf_mutex);
264 free_page((unsigned long)port->xmit_buf);
265 port->xmit_buf = NULL;
266 INIT_KFIFO(port->xmit_fifo);
267 mutex_unlock(&port->buf_mutex);
268}
269EXPORT_SYMBOL(tty_port_free_xmit_buf);
270
271/**
272 * tty_port_destroy - destroy inited port
273 * @port: tty port to be destroyed
274 *
275 * When a port was initialized using tty_port_init(), one has to destroy the
276 * port by this function. Either indirectly by using &tty_port refcounting
277 * (tty_port_put()) or directly if refcounting is not used.
278 */
279void tty_port_destroy(struct tty_port *port)
280{
281 tty_buffer_cancel_work(port);
282 tty_buffer_free_all(port);
283}
284EXPORT_SYMBOL(tty_port_destroy);
285
286static void tty_port_destructor(struct kref *kref)
287{
288 struct tty_port *port = container_of(kref, struct tty_port, kref);
289
290 /* check if last port ref was dropped before tty release */
291 if (WARN_ON(port->itty))
292 return;
293 free_page((unsigned long)port->xmit_buf);
294 tty_port_destroy(port);
295 if (port->ops && port->ops->destruct)
296 port->ops->destruct(port);
297 else
298 kfree(port);
299}
300
301/**
302 * tty_port_put - drop a reference to tty_port
303 * @port: port to drop a reference of (can be NULL)
304 *
305 * The final put will destroy and free up the @port using
306 * @port->ops->destruct() hook, or using kfree() if not provided.
307 */
308void tty_port_put(struct tty_port *port)
309{
310 if (port)
311 kref_put(&port->kref, tty_port_destructor);
312}
313EXPORT_SYMBOL(tty_port_put);
314
315/**
316 * tty_port_tty_get - get a tty reference
317 * @port: tty port
318 *
319 * Return a refcount protected tty instance or %NULL if the port is not
320 * associated with a tty (eg due to close or hangup).
321 */
322struct tty_struct *tty_port_tty_get(struct tty_port *port)
323{
324 unsigned long flags;
325 struct tty_struct *tty;
326
327 spin_lock_irqsave(&port->lock, flags);
328 tty = tty_kref_get(port->tty);
329 spin_unlock_irqrestore(&port->lock, flags);
330 return tty;
331}
332EXPORT_SYMBOL(tty_port_tty_get);
333
334/**
335 * tty_port_tty_set - set the tty of a port
336 * @port: tty port
337 * @tty: the tty
338 *
339 * Associate the port and tty pair. Manages any internal refcounts. Pass %NULL
340 * to deassociate a port.
341 */
342void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
343{
344 unsigned long flags;
345
346 spin_lock_irqsave(&port->lock, flags);
347 tty_kref_put(port->tty);
348 port->tty = tty_kref_get(tty);
349 spin_unlock_irqrestore(&port->lock, flags);
350}
351EXPORT_SYMBOL(tty_port_tty_set);
352
353/**
354 * tty_port_shutdown - internal helper to shutdown the device
355 * @port: tty port to be shut down
356 * @tty: the associated tty
357 *
358 * It is used by tty_port_hangup() and tty_port_close(). Its task is to
359 * shutdown the device if it was initialized (note consoles remain
360 * functioning). It lowers DTR/RTS (if @tty has HUPCL set) and invokes
361 * @port->ops->shutdown().
362 */
363static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty)
364{
365 mutex_lock(&port->mutex);
366 if (port->console)
367 goto out;
368
369 if (tty_port_initialized(port)) {
370 tty_port_set_initialized(port, false);
371 /*
372 * Drop DTR/RTS if HUPCL is set. This causes any attached
373 * modem to hang up the line.
374 */
375 if (tty && C_HUPCL(tty))
376 tty_port_lower_dtr_rts(port);
377
378 if (port->ops->shutdown)
379 port->ops->shutdown(port);
380 }
381out:
382 mutex_unlock(&port->mutex);
383}
384
385/**
386 * tty_port_hangup - hangup helper
387 * @port: tty port
388 *
389 * Perform port level tty hangup flag and count changes. Drop the tty
390 * reference.
391 *
392 * Caller holds tty lock.
393 */
394void tty_port_hangup(struct tty_port *port)
395{
396 struct tty_struct *tty;
397 unsigned long flags;
398
399 spin_lock_irqsave(&port->lock, flags);
400 port->count = 0;
401 tty = port->tty;
402 if (tty)
403 set_bit(TTY_IO_ERROR, &tty->flags);
404 port->tty = NULL;
405 spin_unlock_irqrestore(&port->lock, flags);
406 tty_port_set_active(port, false);
407 tty_port_shutdown(port, tty);
408 tty_kref_put(tty);
409 wake_up_interruptible(&port->open_wait);
410 wake_up_interruptible(&port->delta_msr_wait);
411}
412EXPORT_SYMBOL(tty_port_hangup);
413
414/**
415 * tty_port_tty_hangup - helper to hang up a tty
416 * @port: tty port
417 * @check_clocal: hang only ttys with %CLOCAL unset?
418 */
419void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
420{
421 struct tty_struct *tty = tty_port_tty_get(port);
422
423 if (tty && (!check_clocal || !C_CLOCAL(tty)))
424 tty_hangup(tty);
425 tty_kref_put(tty);
426}
427EXPORT_SYMBOL_GPL(tty_port_tty_hangup);
428
429/**
430 * tty_port_tty_wakeup - helper to wake up a tty
431 * @port: tty port
432 */
433void tty_port_tty_wakeup(struct tty_port *port)
434{
435 port->client_ops->write_wakeup(port);
436}
437EXPORT_SYMBOL_GPL(tty_port_tty_wakeup);
438
439/**
440 * tty_port_carrier_raised - carrier raised check
441 * @port: tty port
442 *
443 * Wrapper for the carrier detect logic. For the moment this is used
444 * to hide some internal details. This will eventually become entirely
445 * internal to the tty port.
446 */
447bool tty_port_carrier_raised(struct tty_port *port)
448{
449 if (port->ops->carrier_raised == NULL)
450 return true;
451 return port->ops->carrier_raised(port);
452}
453EXPORT_SYMBOL(tty_port_carrier_raised);
454
455/**
456 * tty_port_raise_dtr_rts - Raise DTR/RTS
457 * @port: tty port
458 *
459 * Wrapper for the DTR/RTS raise logic. For the moment this is used to hide
460 * some internal details. This will eventually become entirely internal to the
461 * tty port.
462 */
463void tty_port_raise_dtr_rts(struct tty_port *port)
464{
465 if (port->ops->dtr_rts)
466 port->ops->dtr_rts(port, true);
467}
468EXPORT_SYMBOL(tty_port_raise_dtr_rts);
469
470/**
471 * tty_port_lower_dtr_rts - Lower DTR/RTS
472 * @port: tty port
473 *
474 * Wrapper for the DTR/RTS raise logic. For the moment this is used to hide
475 * some internal details. This will eventually become entirely internal to the
476 * tty port.
477 */
478void tty_port_lower_dtr_rts(struct tty_port *port)
479{
480 if (port->ops->dtr_rts)
481 port->ops->dtr_rts(port, false);
482}
483EXPORT_SYMBOL(tty_port_lower_dtr_rts);
484
485/**
486 * tty_port_block_til_ready - Waiting logic for tty open
487 * @port: the tty port being opened
488 * @tty: the tty device being bound
489 * @filp: the file pointer of the opener or %NULL
490 *
491 * Implement the core POSIX/SuS tty behaviour when opening a tty device.
492 * Handles:
493 *
494 * - hangup (both before and during)
495 * - non blocking open
496 * - rts/dtr/dcd
497 * - signals
498 * - port flags and counts
499 *
500 * The passed @port must implement the @port->ops->carrier_raised method if it
501 * can do carrier detect and the @port->ops->dtr_rts method if it supports
502 * software management of these lines. Note that the dtr/rts raise is done each
503 * iteration as a hangup may have previously dropped them while we wait.
504 *
505 * Caller holds tty lock.
506 *
507 * Note: May drop and reacquire tty lock when blocking, so @tty and @port may
508 * have changed state (eg., may have been hung up).
509 */
510int tty_port_block_til_ready(struct tty_port *port,
511 struct tty_struct *tty, struct file *filp)
512{
513 int do_clocal = 0, retval;
514 unsigned long flags;
515 DEFINE_WAIT(wait);
516
517 /* if non-blocking mode is set we can pass directly to open unless
518 * the port has just hung up or is in another error state.
519 */
520 if (tty_io_error(tty)) {
521 tty_port_set_active(port, true);
522 return 0;
523 }
524 if (filp == NULL || (filp->f_flags & O_NONBLOCK)) {
525 /* Indicate we are open */
526 if (C_BAUD(tty))
527 tty_port_raise_dtr_rts(port);
528 tty_port_set_active(port, true);
529 return 0;
530 }
531
532 if (C_CLOCAL(tty))
533 do_clocal = 1;
534
535 /* Block waiting until we can proceed. We may need to wait for the
536 * carrier, but we must also wait for any close that is in progress
537 * before the next open may complete.
538 */
539
540 retval = 0;
541
542 /* The port lock protects the port counts */
543 spin_lock_irqsave(&port->lock, flags);
544 port->count--;
545 port->blocked_open++;
546 spin_unlock_irqrestore(&port->lock, flags);
547
548 while (1) {
549 /* Indicate we are open */
550 if (C_BAUD(tty) && tty_port_initialized(port))
551 tty_port_raise_dtr_rts(port);
552
553 prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
554 /* Check for a hangup or uninitialised port.
555 * Return accordingly.
556 */
557 if (tty_hung_up_p(filp) || !tty_port_initialized(port)) {
558 if (port->flags & ASYNC_HUP_NOTIFY)
559 retval = -EAGAIN;
560 else
561 retval = -ERESTARTSYS;
562 break;
563 }
564 /*
565 * Probe the carrier. For devices with no carrier detect
566 * tty_port_carrier_raised will always return true.
567 * Never ask drivers if CLOCAL is set, this causes troubles
568 * on some hardware.
569 */
570 if (do_clocal || tty_port_carrier_raised(port))
571 break;
572 if (signal_pending(current)) {
573 retval = -ERESTARTSYS;
574 break;
575 }
576 tty_unlock(tty);
577 schedule();
578 tty_lock(tty);
579 }
580 finish_wait(&port->open_wait, &wait);
581
582 /* Update counts. A parallel hangup will have set count to zero and
583 * we must not mess that up further.
584 */
585 spin_lock_irqsave(&port->lock, flags);
586 if (!tty_hung_up_p(filp))
587 port->count++;
588 port->blocked_open--;
589 spin_unlock_irqrestore(&port->lock, flags);
590 if (retval == 0)
591 tty_port_set_active(port, true);
592 return retval;
593}
594EXPORT_SYMBOL(tty_port_block_til_ready);
595
596static void tty_port_drain_delay(struct tty_port *port, struct tty_struct *tty)
597{
598 unsigned int bps = tty_get_baud_rate(tty);
599 long timeout;
600
601 if (bps > 1200) {
602 timeout = (HZ * 10 * port->drain_delay) / bps;
603 timeout = max_t(long, timeout, HZ / 10);
604 } else {
605 timeout = 2 * HZ;
606 }
607 schedule_timeout_interruptible(timeout);
608}
609
610/**
611 * tty_port_close_start - helper for tty->ops->close, part 1/2
612 * @port: tty_port of the device
613 * @tty: tty being closed
614 * @filp: passed file pointer
615 *
616 * Decrements and checks open count. Flushes the port if this is the last
617 * close. That means, dropping the data from the outpu buffer on the device and
618 * waiting for sending logic to finish. The rest of close handling is performed
619 * in tty_port_close_end().
620 *
621 * Locking: Caller holds tty lock.
622 *
623 * Return: 1 if this is the last close, otherwise 0
624 */
625int tty_port_close_start(struct tty_port *port,
626 struct tty_struct *tty, struct file *filp)
627{
628 unsigned long flags;
629
630 if (tty_hung_up_p(filp))
631 return 0;
632
633 spin_lock_irqsave(&port->lock, flags);
634 if (tty->count == 1 && port->count != 1) {
635 tty_warn(tty, "%s: tty->count = 1 port count = %d\n", __func__,
636 port->count);
637 port->count = 1;
638 }
639 if (--port->count < 0) {
640 tty_warn(tty, "%s: bad port count (%d)\n", __func__,
641 port->count);
642 port->count = 0;
643 }
644
645 if (port->count) {
646 spin_unlock_irqrestore(&port->lock, flags);
647 return 0;
648 }
649 spin_unlock_irqrestore(&port->lock, flags);
650
651 tty->closing = 1;
652
653 if (tty_port_initialized(port)) {
654 /* Don't block on a stalled port, just pull the chain */
655 if (tty->flow.tco_stopped)
656 tty_driver_flush_buffer(tty);
657 if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
658 tty_wait_until_sent(tty, port->closing_wait);
659 if (port->drain_delay)
660 tty_port_drain_delay(port, tty);
661 }
662 /* Flush the ldisc buffering */
663 tty_ldisc_flush(tty);
664
665 /* Report to caller this is the last port reference */
666 return 1;
667}
668EXPORT_SYMBOL(tty_port_close_start);
669
670/**
671 * tty_port_close_end - helper for tty->ops->close, part 2/2
672 * @port: tty_port of the device
673 * @tty: tty being closed
674 *
675 * This is a continuation of the first part: tty_port_close_start(). This
676 * should be called after turning off the device. It flushes the data from the
677 * line discipline and delays the close by @port->close_delay.
678 *
679 * Locking: Caller holds tty lock.
680 */
681void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
682{
683 unsigned long flags;
684
685 tty_ldisc_flush(tty);
686 tty->closing = 0;
687
688 spin_lock_irqsave(&port->lock, flags);
689
690 if (port->blocked_open) {
691 spin_unlock_irqrestore(&port->lock, flags);
692 if (port->close_delay)
693 msleep_interruptible(jiffies_to_msecs(port->close_delay));
694 spin_lock_irqsave(&port->lock, flags);
695 wake_up_interruptible(&port->open_wait);
696 }
697 spin_unlock_irqrestore(&port->lock, flags);
698 tty_port_set_active(port, false);
699}
700EXPORT_SYMBOL(tty_port_close_end);
701
702/**
703 * tty_port_close - generic tty->ops->close handler
704 * @port: tty_port of the device
705 * @tty: tty being closed
706 * @filp: passed file pointer
707 *
708 * It is a generic helper to be used in driver's @tty->ops->close. It wraps a
709 * sequence of tty_port_close_start(), tty_port_shutdown(), and
710 * tty_port_close_end(). The latter two are called only if this is the last
711 * close. See the respective functions for the details.
712 *
713 * Locking: Caller holds tty lock
714 */
715void tty_port_close(struct tty_port *port, struct tty_struct *tty,
716 struct file *filp)
717{
718 if (tty_port_close_start(port, tty, filp) == 0)
719 return;
720 tty_port_shutdown(port, tty);
721 if (!port->console)
722 set_bit(TTY_IO_ERROR, &tty->flags);
723 tty_port_close_end(port, tty);
724 tty_port_tty_set(port, NULL);
725}
726EXPORT_SYMBOL(tty_port_close);
727
728/**
729 * tty_port_install - generic tty->ops->install handler
730 * @port: tty_port of the device
731 * @driver: tty_driver for this device
732 * @tty: tty to be installed
733 *
734 * It is the same as tty_standard_install() except the provided @port is linked
735 * to a concrete tty specified by @tty. Use this or tty_port_register_device()
736 * (or both). Call tty_port_link_device() as a last resort.
737 */
738int tty_port_install(struct tty_port *port, struct tty_driver *driver,
739 struct tty_struct *tty)
740{
741 tty->port = port;
742 return tty_standard_install(driver, tty);
743}
744EXPORT_SYMBOL_GPL(tty_port_install);
745
746/**
747 * tty_port_open - generic tty->ops->open handler
748 * @port: tty_port of the device
749 * @tty: tty to be opened
750 * @filp: passed file pointer
751 *
752 * It is a generic helper to be used in driver's @tty->ops->open. It activates
753 * the devices using @port->ops->activate if not active already. And waits for
754 * the device to be ready using tty_port_block_til_ready() (e.g. raises
755 * DTR/CTS and waits for carrier).
756 *
757 * Note that @port->ops->shutdown is not called when @port->ops->activate
758 * returns an error (on the contrary, @tty->ops->close is).
759 *
760 * Locking: Caller holds tty lock.
761 *
762 * Note: may drop and reacquire tty lock (in tty_port_block_til_ready()) so
763 * @tty and @port may have changed state (eg., may be hung up now).
764 */
765int tty_port_open(struct tty_port *port, struct tty_struct *tty,
766 struct file *filp)
767{
768 spin_lock_irq(&port->lock);
769 ++port->count;
770 spin_unlock_irq(&port->lock);
771 tty_port_tty_set(port, tty);
772
773 /*
774 * Do the device-specific open only if the hardware isn't
775 * already initialized. Serialize open and shutdown using the
776 * port mutex.
777 */
778
779 mutex_lock(&port->mutex);
780
781 if (!tty_port_initialized(port)) {
782 clear_bit(TTY_IO_ERROR, &tty->flags);
783 if (port->ops->activate) {
784 int retval = port->ops->activate(port, tty);
785
786 if (retval) {
787 mutex_unlock(&port->mutex);
788 return retval;
789 }
790 }
791 tty_port_set_initialized(port, true);
792 }
793 mutex_unlock(&port->mutex);
794 return tty_port_block_til_ready(port, tty, filp);
795}
796EXPORT_SYMBOL(tty_port_open);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Tty port functions
4 */
5
6#include <linux/types.h>
7#include <linux/errno.h>
8#include <linux/tty.h>
9#include <linux/tty_driver.h>
10#include <linux/tty_flip.h>
11#include <linux/serial.h>
12#include <linux/timer.h>
13#include <linux/string.h>
14#include <linux/slab.h>
15#include <linux/sched/signal.h>
16#include <linux/wait.h>
17#include <linux/bitops.h>
18#include <linux/delay.h>
19#include <linux/module.h>
20#include <linux/serdev.h>
21
22static int tty_port_default_receive_buf(struct tty_port *port,
23 const unsigned char *p,
24 const unsigned char *f, size_t count)
25{
26 int ret;
27 struct tty_struct *tty;
28 struct tty_ldisc *disc;
29
30 tty = READ_ONCE(port->itty);
31 if (!tty)
32 return 0;
33
34 disc = tty_ldisc_ref(tty);
35 if (!disc)
36 return 0;
37
38 ret = tty_ldisc_receive_buf(disc, p, (char *)f, count);
39
40 tty_ldisc_deref(disc);
41
42 return ret;
43}
44
45static void tty_port_default_wakeup(struct tty_port *port)
46{
47 struct tty_struct *tty = tty_port_tty_get(port);
48
49 if (tty) {
50 tty_wakeup(tty);
51 tty_kref_put(tty);
52 }
53}
54
55static const struct tty_port_client_operations default_client_ops = {
56 .receive_buf = tty_port_default_receive_buf,
57 .write_wakeup = tty_port_default_wakeup,
58};
59
60void tty_port_init(struct tty_port *port)
61{
62 memset(port, 0, sizeof(*port));
63 tty_buffer_init(port);
64 init_waitqueue_head(&port->open_wait);
65 init_waitqueue_head(&port->delta_msr_wait);
66 mutex_init(&port->mutex);
67 mutex_init(&port->buf_mutex);
68 spin_lock_init(&port->lock);
69 port->close_delay = (50 * HZ) / 100;
70 port->closing_wait = (3000 * HZ) / 100;
71 port->client_ops = &default_client_ops;
72 kref_init(&port->kref);
73}
74EXPORT_SYMBOL(tty_port_init);
75
76/**
77 * tty_port_link_device - link tty and tty_port
78 * @port: tty_port of the device
79 * @driver: tty_driver for this device
80 * @index: index of the tty
81 *
82 * Provide the tty layer with a link from a tty (specified by @index) to a
83 * tty_port (@port). Use this only if neither tty_port_register_device nor
84 * tty_port_install is used in the driver. If used, this has to be called before
85 * tty_register_driver.
86 */
87void tty_port_link_device(struct tty_port *port,
88 struct tty_driver *driver, unsigned index)
89{
90 if (WARN_ON(index >= driver->num))
91 return;
92 driver->ports[index] = port;
93}
94EXPORT_SYMBOL_GPL(tty_port_link_device);
95
96/**
97 * tty_port_register_device - register tty device
98 * @port: tty_port of the device
99 * @driver: tty_driver for this device
100 * @index: index of the tty
101 * @device: parent if exists, otherwise NULL
102 *
103 * It is the same as tty_register_device except the provided @port is linked to
104 * a concrete tty specified by @index. Use this or tty_port_install (or both).
105 * Call tty_port_link_device as a last resort.
106 */
107struct device *tty_port_register_device(struct tty_port *port,
108 struct tty_driver *driver, unsigned index,
109 struct device *device)
110{
111 return tty_port_register_device_attr(port, driver, index, device, NULL, NULL);
112}
113EXPORT_SYMBOL_GPL(tty_port_register_device);
114
115/**
116 * tty_port_register_device_attr - register tty device
117 * @port: tty_port of the device
118 * @driver: tty_driver for this device
119 * @index: index of the tty
120 * @device: parent if exists, otherwise NULL
121 * @drvdata: Driver data to be set to device.
122 * @attr_grp: Attribute group to be set on device.
123 *
124 * It is the same as tty_register_device_attr except the provided @port is
125 * linked to a concrete tty specified by @index. Use this or tty_port_install
126 * (or both). Call tty_port_link_device as a last resort.
127 */
128struct device *tty_port_register_device_attr(struct tty_port *port,
129 struct tty_driver *driver, unsigned index,
130 struct device *device, void *drvdata,
131 const struct attribute_group **attr_grp)
132{
133 tty_port_link_device(port, driver, index);
134 return tty_register_device_attr(driver, index, device, drvdata,
135 attr_grp);
136}
137EXPORT_SYMBOL_GPL(tty_port_register_device_attr);
138
139/**
140 * tty_port_register_device_attr_serdev - register tty or serdev device
141 * @port: tty_port of the device
142 * @driver: tty_driver for this device
143 * @index: index of the tty
144 * @device: parent if exists, otherwise NULL
145 * @drvdata: driver data for the device
146 * @attr_grp: attribute group for the device
147 *
148 * Register a serdev or tty device depending on if the parent device has any
149 * defined serdev clients or not.
150 */
151struct device *tty_port_register_device_attr_serdev(struct tty_port *port,
152 struct tty_driver *driver, unsigned index,
153 struct device *device, void *drvdata,
154 const struct attribute_group **attr_grp)
155{
156 struct device *dev;
157
158 tty_port_link_device(port, driver, index);
159
160 dev = serdev_tty_port_register(port, device, driver, index);
161 if (PTR_ERR(dev) != -ENODEV) {
162 /* Skip creating cdev if we registered a serdev device */
163 return dev;
164 }
165
166 return tty_register_device_attr(driver, index, device, drvdata,
167 attr_grp);
168}
169EXPORT_SYMBOL_GPL(tty_port_register_device_attr_serdev);
170
171/**
172 * tty_port_register_device_serdev - register tty or serdev device
173 * @port: tty_port of the device
174 * @driver: tty_driver for this device
175 * @index: index of the tty
176 * @device: parent if exists, otherwise NULL
177 *
178 * Register a serdev or tty device depending on if the parent device has any
179 * defined serdev clients or not.
180 */
181struct device *tty_port_register_device_serdev(struct tty_port *port,
182 struct tty_driver *driver, unsigned index,
183 struct device *device)
184{
185 return tty_port_register_device_attr_serdev(port, driver, index,
186 device, NULL, NULL);
187}
188EXPORT_SYMBOL_GPL(tty_port_register_device_serdev);
189
190/**
191 * tty_port_unregister_device - deregister a tty or serdev device
192 * @port: tty_port of the device
193 * @driver: tty_driver for this device
194 * @index: index of the tty
195 *
196 * If a tty or serdev device is registered with a call to
197 * tty_port_register_device_serdev() then this function must be called when
198 * the device is gone.
199 */
200void tty_port_unregister_device(struct tty_port *port,
201 struct tty_driver *driver, unsigned index)
202{
203 int ret;
204
205 ret = serdev_tty_port_unregister(port);
206 if (ret == 0)
207 return;
208
209 tty_unregister_device(driver, index);
210}
211EXPORT_SYMBOL_GPL(tty_port_unregister_device);
212
213int tty_port_alloc_xmit_buf(struct tty_port *port)
214{
215 /* We may sleep in get_zeroed_page() */
216 mutex_lock(&port->buf_mutex);
217 if (port->xmit_buf == NULL)
218 port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
219 mutex_unlock(&port->buf_mutex);
220 if (port->xmit_buf == NULL)
221 return -ENOMEM;
222 return 0;
223}
224EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
225
226void tty_port_free_xmit_buf(struct tty_port *port)
227{
228 mutex_lock(&port->buf_mutex);
229 if (port->xmit_buf != NULL) {
230 free_page((unsigned long)port->xmit_buf);
231 port->xmit_buf = NULL;
232 }
233 mutex_unlock(&port->buf_mutex);
234}
235EXPORT_SYMBOL(tty_port_free_xmit_buf);
236
237/**
238 * tty_port_destroy -- destroy inited port
239 * @port: tty port to be destroyed
240 *
241 * When a port was initialized using tty_port_init, one has to destroy the
242 * port by this function. Either indirectly by using tty_port refcounting
243 * (tty_port_put) or directly if refcounting is not used.
244 */
245void tty_port_destroy(struct tty_port *port)
246{
247 tty_buffer_cancel_work(port);
248 tty_buffer_free_all(port);
249}
250EXPORT_SYMBOL(tty_port_destroy);
251
252static void tty_port_destructor(struct kref *kref)
253{
254 struct tty_port *port = container_of(kref, struct tty_port, kref);
255
256 /* check if last port ref was dropped before tty release */
257 if (WARN_ON(port->itty))
258 return;
259 if (port->xmit_buf)
260 free_page((unsigned long)port->xmit_buf);
261 tty_port_destroy(port);
262 if (port->ops && port->ops->destruct)
263 port->ops->destruct(port);
264 else
265 kfree(port);
266}
267
268void tty_port_put(struct tty_port *port)
269{
270 if (port)
271 kref_put(&port->kref, tty_port_destructor);
272}
273EXPORT_SYMBOL(tty_port_put);
274
275/**
276 * tty_port_tty_get - get a tty reference
277 * @port: tty port
278 *
279 * Return a refcount protected tty instance or NULL if the port is not
280 * associated with a tty (eg due to close or hangup)
281 */
282
283struct tty_struct *tty_port_tty_get(struct tty_port *port)
284{
285 unsigned long flags;
286 struct tty_struct *tty;
287
288 spin_lock_irqsave(&port->lock, flags);
289 tty = tty_kref_get(port->tty);
290 spin_unlock_irqrestore(&port->lock, flags);
291 return tty;
292}
293EXPORT_SYMBOL(tty_port_tty_get);
294
295/**
296 * tty_port_tty_set - set the tty of a port
297 * @port: tty port
298 * @tty: the tty
299 *
300 * Associate the port and tty pair. Manages any internal refcounts.
301 * Pass NULL to deassociate a port
302 */
303
304void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
305{
306 unsigned long flags;
307
308 spin_lock_irqsave(&port->lock, flags);
309 tty_kref_put(port->tty);
310 port->tty = tty_kref_get(tty);
311 spin_unlock_irqrestore(&port->lock, flags);
312}
313EXPORT_SYMBOL(tty_port_tty_set);
314
315static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty)
316{
317 mutex_lock(&port->mutex);
318 if (port->console)
319 goto out;
320
321 if (tty_port_initialized(port)) {
322 tty_port_set_initialized(port, 0);
323 /*
324 * Drop DTR/RTS if HUPCL is set. This causes any attached
325 * modem to hang up the line.
326 */
327 if (tty && C_HUPCL(tty))
328 tty_port_lower_dtr_rts(port);
329
330 if (port->ops->shutdown)
331 port->ops->shutdown(port);
332 }
333out:
334 mutex_unlock(&port->mutex);
335}
336
337/**
338 * tty_port_hangup - hangup helper
339 * @port: tty port
340 *
341 * Perform port level tty hangup flag and count changes. Drop the tty
342 * reference.
343 *
344 * Caller holds tty lock.
345 */
346
347void tty_port_hangup(struct tty_port *port)
348{
349 struct tty_struct *tty;
350 unsigned long flags;
351
352 spin_lock_irqsave(&port->lock, flags);
353 port->count = 0;
354 tty = port->tty;
355 if (tty)
356 set_bit(TTY_IO_ERROR, &tty->flags);
357 port->tty = NULL;
358 spin_unlock_irqrestore(&port->lock, flags);
359 tty_port_set_active(port, 0);
360 tty_port_shutdown(port, tty);
361 tty_kref_put(tty);
362 wake_up_interruptible(&port->open_wait);
363 wake_up_interruptible(&port->delta_msr_wait);
364}
365EXPORT_SYMBOL(tty_port_hangup);
366
367/**
368 * tty_port_tty_hangup - helper to hang up a tty
369 *
370 * @port: tty port
371 * @check_clocal: hang only ttys with CLOCAL unset?
372 */
373void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
374{
375 struct tty_struct *tty = tty_port_tty_get(port);
376
377 if (tty && (!check_clocal || !C_CLOCAL(tty)))
378 tty_hangup(tty);
379 tty_kref_put(tty);
380}
381EXPORT_SYMBOL_GPL(tty_port_tty_hangup);
382
383/**
384 * tty_port_tty_wakeup - helper to wake up a tty
385 *
386 * @port: tty port
387 */
388void tty_port_tty_wakeup(struct tty_port *port)
389{
390 port->client_ops->write_wakeup(port);
391}
392EXPORT_SYMBOL_GPL(tty_port_tty_wakeup);
393
394/**
395 * tty_port_carrier_raised - carrier raised check
396 * @port: tty port
397 *
398 * Wrapper for the carrier detect logic. For the moment this is used
399 * to hide some internal details. This will eventually become entirely
400 * internal to the tty port.
401 */
402
403int tty_port_carrier_raised(struct tty_port *port)
404{
405 if (port->ops->carrier_raised == NULL)
406 return 1;
407 return port->ops->carrier_raised(port);
408}
409EXPORT_SYMBOL(tty_port_carrier_raised);
410
411/**
412 * tty_port_raise_dtr_rts - Raise DTR/RTS
413 * @port: tty port
414 *
415 * Wrapper for the DTR/RTS raise logic. For the moment this is used
416 * to hide some internal details. This will eventually become entirely
417 * internal to the tty port.
418 */
419
420void tty_port_raise_dtr_rts(struct tty_port *port)
421{
422 if (port->ops->dtr_rts)
423 port->ops->dtr_rts(port, 1);
424}
425EXPORT_SYMBOL(tty_port_raise_dtr_rts);
426
427/**
428 * tty_port_lower_dtr_rts - Lower DTR/RTS
429 * @port: tty port
430 *
431 * Wrapper for the DTR/RTS raise logic. For the moment this is used
432 * to hide some internal details. This will eventually become entirely
433 * internal to the tty port.
434 */
435
436void tty_port_lower_dtr_rts(struct tty_port *port)
437{
438 if (port->ops->dtr_rts)
439 port->ops->dtr_rts(port, 0);
440}
441EXPORT_SYMBOL(tty_port_lower_dtr_rts);
442
443/**
444 * tty_port_block_til_ready - Waiting logic for tty open
445 * @port: the tty port being opened
446 * @tty: the tty device being bound
447 * @filp: the file pointer of the opener or NULL
448 *
449 * Implement the core POSIX/SuS tty behaviour when opening a tty device.
450 * Handles:
451 * - hangup (both before and during)
452 * - non blocking open
453 * - rts/dtr/dcd
454 * - signals
455 * - port flags and counts
456 *
457 * The passed tty_port must implement the carrier_raised method if it can
458 * do carrier detect and the dtr_rts method if it supports software
459 * management of these lines. Note that the dtr/rts raise is done each
460 * iteration as a hangup may have previously dropped them while we wait.
461 *
462 * Caller holds tty lock.
463 *
464 * NB: May drop and reacquire tty lock when blocking, so tty and tty_port
465 * may have changed state (eg., may have been hung up).
466 */
467
468int tty_port_block_til_ready(struct tty_port *port,
469 struct tty_struct *tty, struct file *filp)
470{
471 int do_clocal = 0, retval;
472 unsigned long flags;
473 DEFINE_WAIT(wait);
474
475 /* if non-blocking mode is set we can pass directly to open unless
476 the port has just hung up or is in another error state */
477 if (tty_io_error(tty)) {
478 tty_port_set_active(port, 1);
479 return 0;
480 }
481 if (filp == NULL || (filp->f_flags & O_NONBLOCK)) {
482 /* Indicate we are open */
483 if (C_BAUD(tty))
484 tty_port_raise_dtr_rts(port);
485 tty_port_set_active(port, 1);
486 return 0;
487 }
488
489 if (C_CLOCAL(tty))
490 do_clocal = 1;
491
492 /* Block waiting until we can proceed. We may need to wait for the
493 carrier, but we must also wait for any close that is in progress
494 before the next open may complete */
495
496 retval = 0;
497
498 /* The port lock protects the port counts */
499 spin_lock_irqsave(&port->lock, flags);
500 port->count--;
501 port->blocked_open++;
502 spin_unlock_irqrestore(&port->lock, flags);
503
504 while (1) {
505 /* Indicate we are open */
506 if (C_BAUD(tty) && tty_port_initialized(port))
507 tty_port_raise_dtr_rts(port);
508
509 prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
510 /* Check for a hangup or uninitialised port.
511 Return accordingly */
512 if (tty_hung_up_p(filp) || !tty_port_initialized(port)) {
513 if (port->flags & ASYNC_HUP_NOTIFY)
514 retval = -EAGAIN;
515 else
516 retval = -ERESTARTSYS;
517 break;
518 }
519 /*
520 * Probe the carrier. For devices with no carrier detect
521 * tty_port_carrier_raised will always return true.
522 * Never ask drivers if CLOCAL is set, this causes troubles
523 * on some hardware.
524 */
525 if (do_clocal || tty_port_carrier_raised(port))
526 break;
527 if (signal_pending(current)) {
528 retval = -ERESTARTSYS;
529 break;
530 }
531 tty_unlock(tty);
532 schedule();
533 tty_lock(tty);
534 }
535 finish_wait(&port->open_wait, &wait);
536
537 /* Update counts. A parallel hangup will have set count to zero and
538 we must not mess that up further */
539 spin_lock_irqsave(&port->lock, flags);
540 if (!tty_hung_up_p(filp))
541 port->count++;
542 port->blocked_open--;
543 spin_unlock_irqrestore(&port->lock, flags);
544 if (retval == 0)
545 tty_port_set_active(port, 1);
546 return retval;
547}
548EXPORT_SYMBOL(tty_port_block_til_ready);
549
550static void tty_port_drain_delay(struct tty_port *port, struct tty_struct *tty)
551{
552 unsigned int bps = tty_get_baud_rate(tty);
553 long timeout;
554
555 if (bps > 1200) {
556 timeout = (HZ * 10 * port->drain_delay) / bps;
557 timeout = max_t(long, timeout, HZ / 10);
558 } else {
559 timeout = 2 * HZ;
560 }
561 schedule_timeout_interruptible(timeout);
562}
563
564/* Caller holds tty lock. */
565int tty_port_close_start(struct tty_port *port,
566 struct tty_struct *tty, struct file *filp)
567{
568 unsigned long flags;
569
570 if (tty_hung_up_p(filp))
571 return 0;
572
573 spin_lock_irqsave(&port->lock, flags);
574 if (tty->count == 1 && port->count != 1) {
575 tty_warn(tty, "%s: tty->count = 1 port count = %d\n", __func__,
576 port->count);
577 port->count = 1;
578 }
579 if (--port->count < 0) {
580 tty_warn(tty, "%s: bad port count (%d)\n", __func__,
581 port->count);
582 port->count = 0;
583 }
584
585 if (port->count) {
586 spin_unlock_irqrestore(&port->lock, flags);
587 return 0;
588 }
589 spin_unlock_irqrestore(&port->lock, flags);
590
591 tty->closing = 1;
592
593 if (tty_port_initialized(port)) {
594 /* Don't block on a stalled port, just pull the chain */
595 if (tty->flow_stopped)
596 tty_driver_flush_buffer(tty);
597 if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
598 tty_wait_until_sent(tty, port->closing_wait);
599 if (port->drain_delay)
600 tty_port_drain_delay(port, tty);
601 }
602 /* Flush the ldisc buffering */
603 tty_ldisc_flush(tty);
604
605 /* Report to caller this is the last port reference */
606 return 1;
607}
608EXPORT_SYMBOL(tty_port_close_start);
609
610/* Caller holds tty lock */
611void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
612{
613 unsigned long flags;
614
615 tty_ldisc_flush(tty);
616 tty->closing = 0;
617
618 spin_lock_irqsave(&port->lock, flags);
619
620 if (port->blocked_open) {
621 spin_unlock_irqrestore(&port->lock, flags);
622 if (port->close_delay)
623 msleep_interruptible(jiffies_to_msecs(port->close_delay));
624 spin_lock_irqsave(&port->lock, flags);
625 wake_up_interruptible(&port->open_wait);
626 }
627 spin_unlock_irqrestore(&port->lock, flags);
628 tty_port_set_active(port, 0);
629}
630EXPORT_SYMBOL(tty_port_close_end);
631
632/**
633 * tty_port_close
634 *
635 * Caller holds tty lock
636 */
637void tty_port_close(struct tty_port *port, struct tty_struct *tty,
638 struct file *filp)
639{
640 if (tty_port_close_start(port, tty, filp) == 0)
641 return;
642 tty_port_shutdown(port, tty);
643 set_bit(TTY_IO_ERROR, &tty->flags);
644 tty_port_close_end(port, tty);
645 tty_port_tty_set(port, NULL);
646}
647EXPORT_SYMBOL(tty_port_close);
648
649/**
650 * tty_port_install - generic tty->ops->install handler
651 * @port: tty_port of the device
652 * @driver: tty_driver for this device
653 * @tty: tty to be installed
654 *
655 * It is the same as tty_standard_install except the provided @port is linked
656 * to a concrete tty specified by @tty. Use this or tty_port_register_device
657 * (or both). Call tty_port_link_device as a last resort.
658 */
659int tty_port_install(struct tty_port *port, struct tty_driver *driver,
660 struct tty_struct *tty)
661{
662 tty->port = port;
663 return tty_standard_install(driver, tty);
664}
665EXPORT_SYMBOL_GPL(tty_port_install);
666
667/**
668 * tty_port_open
669 *
670 * Caller holds tty lock.
671 *
672 * NB: may drop and reacquire tty lock (in tty_port_block_til_ready()) so
673 * tty and tty_port may have changed state (eg., may be hung up now)
674 */
675int tty_port_open(struct tty_port *port, struct tty_struct *tty,
676 struct file *filp)
677{
678 spin_lock_irq(&port->lock);
679 ++port->count;
680 spin_unlock_irq(&port->lock);
681 tty_port_tty_set(port, tty);
682
683 /*
684 * Do the device-specific open only if the hardware isn't
685 * already initialized. Serialize open and shutdown using the
686 * port mutex.
687 */
688
689 mutex_lock(&port->mutex);
690
691 if (!tty_port_initialized(port)) {
692 clear_bit(TTY_IO_ERROR, &tty->flags);
693 if (port->ops->activate) {
694 int retval = port->ops->activate(port, tty);
695 if (retval) {
696 mutex_unlock(&port->mutex);
697 return retval;
698 }
699 }
700 tty_port_set_initialized(port, 1);
701 }
702 mutex_unlock(&port->mutex);
703 return tty_port_block_til_ready(port, tty, filp);
704}
705
706EXPORT_SYMBOL(tty_port_open);