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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
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
55const struct tty_port_client_operations tty_port_default_client_ops = {
56 .receive_buf = tty_port_default_receive_buf,
57 .write_wakeup = tty_port_default_wakeup,
58};
59EXPORT_SYMBOL_GPL(tty_port_default_client_ops);
60
61void tty_port_init(struct tty_port *port)
62{
63 memset(port, 0, sizeof(*port));
64 tty_buffer_init(port);
65 init_waitqueue_head(&port->open_wait);
66 init_waitqueue_head(&port->delta_msr_wait);
67 mutex_init(&port->mutex);
68 mutex_init(&port->buf_mutex);
69 spin_lock_init(&port->lock);
70 port->close_delay = (50 * HZ) / 100;
71 port->closing_wait = (3000 * HZ) / 100;
72 port->client_ops = &tty_port_default_client_ops;
73 kref_init(&port->kref);
74}
75EXPORT_SYMBOL(tty_port_init);
76
77/**
78 * tty_port_link_device - link tty and tty_port
79 * @port: tty_port of the device
80 * @driver: tty_driver for this device
81 * @index: index of the tty
82 *
83 * Provide the tty layer with a link from a tty (specified by @index) to a
84 * tty_port (@port). Use this only if neither tty_port_register_device nor
85 * tty_port_install is used in the driver. If used, this has to be called before
86 * tty_register_driver.
87 */
88void tty_port_link_device(struct tty_port *port,
89 struct tty_driver *driver, unsigned index)
90{
91 if (WARN_ON(index >= driver->num))
92 return;
93 driver->ports[index] = port;
94}
95EXPORT_SYMBOL_GPL(tty_port_link_device);
96
97/**
98 * tty_port_register_device - register tty device
99 * @port: tty_port of the device
100 * @driver: tty_driver for this device
101 * @index: index of the tty
102 * @device: parent if exists, otherwise NULL
103 *
104 * It is the same as tty_register_device except the provided @port is linked to
105 * a concrete tty specified by @index. Use this or tty_port_install (or both).
106 * Call tty_port_link_device as a last resort.
107 */
108struct device *tty_port_register_device(struct tty_port *port,
109 struct tty_driver *driver, unsigned index,
110 struct device *device)
111{
112 return tty_port_register_device_attr(port, driver, index, device, NULL, NULL);
113}
114EXPORT_SYMBOL_GPL(tty_port_register_device);
115
116/**
117 * tty_port_register_device_attr - register tty device
118 * @port: tty_port of the device
119 * @driver: tty_driver for this device
120 * @index: index of the tty
121 * @device: parent if exists, otherwise NULL
122 * @drvdata: Driver data to be set to device.
123 * @attr_grp: Attribute group to be set on device.
124 *
125 * It is the same as tty_register_device_attr except the provided @port is
126 * linked to a concrete tty specified by @index. Use this or tty_port_install
127 * (or both). Call tty_port_link_device as a last resort.
128 */
129struct device *tty_port_register_device_attr(struct tty_port *port,
130 struct tty_driver *driver, unsigned index,
131 struct device *device, void *drvdata,
132 const struct attribute_group **attr_grp)
133{
134 tty_port_link_device(port, driver, index);
135 return tty_register_device_attr(driver, index, device, drvdata,
136 attr_grp);
137}
138EXPORT_SYMBOL_GPL(tty_port_register_device_attr);
139
140/**
141 * tty_port_register_device_attr_serdev - register tty or serdev device
142 * @port: tty_port of the device
143 * @driver: tty_driver for this device
144 * @index: index of the tty
145 * @device: parent if exists, otherwise NULL
146 * @drvdata: driver data for the device
147 * @attr_grp: attribute group for the device
148 *
149 * Register a serdev or tty device depending on if the parent device has any
150 * defined serdev clients or not.
151 */
152struct device *tty_port_register_device_attr_serdev(struct tty_port *port,
153 struct tty_driver *driver, unsigned index,
154 struct device *device, void *drvdata,
155 const struct attribute_group **attr_grp)
156{
157 struct device *dev;
158
159 tty_port_link_device(port, driver, index);
160
161 dev = serdev_tty_port_register(port, device, driver, index);
162 if (PTR_ERR(dev) != -ENODEV) {
163 /* Skip creating cdev if we registered a serdev device */
164 return dev;
165 }
166
167 return tty_register_device_attr(driver, index, device, drvdata,
168 attr_grp);
169}
170EXPORT_SYMBOL_GPL(tty_port_register_device_attr_serdev);
171
172/**
173 * tty_port_register_device_serdev - register tty or serdev device
174 * @port: tty_port of the device
175 * @driver: tty_driver for this device
176 * @index: index of the tty
177 * @device: parent if exists, otherwise NULL
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_serdev(struct tty_port *port,
183 struct tty_driver *driver, unsigned index,
184 struct device *device)
185{
186 return tty_port_register_device_attr_serdev(port, driver, index,
187 device, NULL, NULL);
188}
189EXPORT_SYMBOL_GPL(tty_port_register_device_serdev);
190
191/**
192 * tty_port_unregister_device - deregister a tty or serdev device
193 * @port: tty_port of the device
194 * @driver: tty_driver for this device
195 * @index: index of the tty
196 *
197 * If a tty or serdev device is registered with a call to
198 * tty_port_register_device_serdev() then this function must be called when
199 * the device is gone.
200 */
201void tty_port_unregister_device(struct tty_port *port,
202 struct tty_driver *driver, unsigned index)
203{
204 int ret;
205
206 ret = serdev_tty_port_unregister(port);
207 if (ret == 0)
208 return;
209
210 tty_unregister_device(driver, index);
211}
212EXPORT_SYMBOL_GPL(tty_port_unregister_device);
213
214int tty_port_alloc_xmit_buf(struct tty_port *port)
215{
216 /* We may sleep in get_zeroed_page() */
217 mutex_lock(&port->buf_mutex);
218 if (port->xmit_buf == NULL)
219 port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
220 mutex_unlock(&port->buf_mutex);
221 if (port->xmit_buf == NULL)
222 return -ENOMEM;
223 return 0;
224}
225EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
226
227void tty_port_free_xmit_buf(struct tty_port *port)
228{
229 mutex_lock(&port->buf_mutex);
230 if (port->xmit_buf != NULL) {
231 free_page((unsigned long)port->xmit_buf);
232 port->xmit_buf = NULL;
233 }
234 mutex_unlock(&port->buf_mutex);
235}
236EXPORT_SYMBOL(tty_port_free_xmit_buf);
237
238/**
239 * tty_port_destroy -- destroy inited port
240 * @port: tty port to be destroyed
241 *
242 * When a port was initialized using tty_port_init, one has to destroy the
243 * port by this function. Either indirectly by using tty_port refcounting
244 * (tty_port_put) or directly if refcounting is not used.
245 */
246void tty_port_destroy(struct tty_port *port)
247{
248 tty_buffer_cancel_work(port);
249 tty_buffer_free_all(port);
250}
251EXPORT_SYMBOL(tty_port_destroy);
252
253static void tty_port_destructor(struct kref *kref)
254{
255 struct tty_port *port = container_of(kref, struct tty_port, kref);
256
257 /* check if last port ref was dropped before tty release */
258 if (WARN_ON(port->itty))
259 return;
260 if (port->xmit_buf)
261 free_page((unsigned long)port->xmit_buf);
262 tty_port_destroy(port);
263 if (port->ops && port->ops->destruct)
264 port->ops->destruct(port);
265 else
266 kfree(port);
267}
268
269void tty_port_put(struct tty_port *port)
270{
271 if (port)
272 kref_put(&port->kref, tty_port_destructor);
273}
274EXPORT_SYMBOL(tty_port_put);
275
276/**
277 * tty_port_tty_get - get a tty reference
278 * @port: tty port
279 *
280 * Return a refcount protected tty instance or NULL if the port is not
281 * associated with a tty (eg due to close or hangup)
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 */
303void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
304{
305 unsigned long flags;
306
307 spin_lock_irqsave(&port->lock, flags);
308 tty_kref_put(port->tty);
309 port->tty = tty_kref_get(tty);
310 spin_unlock_irqrestore(&port->lock, flags);
311}
312EXPORT_SYMBOL(tty_port_tty_set);
313
314static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty)
315{
316 mutex_lock(&port->mutex);
317 if (port->console)
318 goto out;
319
320 if (tty_port_initialized(port)) {
321 tty_port_set_initialized(port, 0);
322 /*
323 * Drop DTR/RTS if HUPCL is set. This causes any attached
324 * modem to hang up the line.
325 */
326 if (tty && C_HUPCL(tty))
327 tty_port_lower_dtr_rts(port);
328
329 if (port->ops->shutdown)
330 port->ops->shutdown(port);
331 }
332out:
333 mutex_unlock(&port->mutex);
334}
335
336/**
337 * tty_port_hangup - hangup helper
338 * @port: tty port
339 *
340 * Perform port level tty hangup flag and count changes. Drop the tty
341 * reference.
342 *
343 * Caller holds tty lock.
344 */
345void tty_port_hangup(struct tty_port *port)
346{
347 struct tty_struct *tty;
348 unsigned long flags;
349
350 spin_lock_irqsave(&port->lock, flags);
351 port->count = 0;
352 tty = port->tty;
353 if (tty)
354 set_bit(TTY_IO_ERROR, &tty->flags);
355 port->tty = NULL;
356 spin_unlock_irqrestore(&port->lock, flags);
357 tty_port_set_active(port, 0);
358 tty_port_shutdown(port, tty);
359 tty_kref_put(tty);
360 wake_up_interruptible(&port->open_wait);
361 wake_up_interruptible(&port->delta_msr_wait);
362}
363EXPORT_SYMBOL(tty_port_hangup);
364
365/**
366 * tty_port_tty_hangup - helper to hang up a tty
367 *
368 * @port: tty port
369 * @check_clocal: hang only ttys with CLOCAL unset?
370 */
371void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
372{
373 struct tty_struct *tty = tty_port_tty_get(port);
374
375 if (tty && (!check_clocal || !C_CLOCAL(tty)))
376 tty_hangup(tty);
377 tty_kref_put(tty);
378}
379EXPORT_SYMBOL_GPL(tty_port_tty_hangup);
380
381/**
382 * tty_port_tty_wakeup - helper to wake up a tty
383 *
384 * @port: tty port
385 */
386void tty_port_tty_wakeup(struct tty_port *port)
387{
388 port->client_ops->write_wakeup(port);
389}
390EXPORT_SYMBOL_GPL(tty_port_tty_wakeup);
391
392/**
393 * tty_port_carrier_raised - carrier raised check
394 * @port: tty port
395 *
396 * Wrapper for the carrier detect logic. For the moment this is used
397 * to hide some internal details. This will eventually become entirely
398 * internal to the tty port.
399 */
400int tty_port_carrier_raised(struct tty_port *port)
401{
402 if (port->ops->carrier_raised == NULL)
403 return 1;
404 return port->ops->carrier_raised(port);
405}
406EXPORT_SYMBOL(tty_port_carrier_raised);
407
408/**
409 * tty_port_raise_dtr_rts - Raise DTR/RTS
410 * @port: tty port
411 *
412 * Wrapper for the DTR/RTS raise logic. For the moment this is used
413 * to hide some internal details. This will eventually become entirely
414 * internal to the tty port.
415 */
416void tty_port_raise_dtr_rts(struct tty_port *port)
417{
418 if (port->ops->dtr_rts)
419 port->ops->dtr_rts(port, 1);
420}
421EXPORT_SYMBOL(tty_port_raise_dtr_rts);
422
423/**
424 * tty_port_lower_dtr_rts - Lower DTR/RTS
425 * @port: tty port
426 *
427 * Wrapper for the DTR/RTS raise logic. For the moment this is used
428 * to hide some internal details. This will eventually become entirely
429 * internal to the tty port.
430 */
431void tty_port_lower_dtr_rts(struct tty_port *port)
432{
433 if (port->ops->dtr_rts)
434 port->ops->dtr_rts(port, 0);
435}
436EXPORT_SYMBOL(tty_port_lower_dtr_rts);
437
438/**
439 * tty_port_block_til_ready - Waiting logic for tty open
440 * @port: the tty port being opened
441 * @tty: the tty device being bound
442 * @filp: the file pointer of the opener or NULL
443 *
444 * Implement the core POSIX/SuS tty behaviour when opening a tty device.
445 * Handles:
446 * - hangup (both before and during)
447 * - non blocking open
448 * - rts/dtr/dcd
449 * - signals
450 * - port flags and counts
451 *
452 * The passed tty_port must implement the carrier_raised method if it can
453 * do carrier detect and the dtr_rts method if it supports software
454 * management of these lines. Note that the dtr/rts raise is done each
455 * iteration as a hangup may have previously dropped them while we wait.
456 *
457 * Caller holds tty lock.
458 *
459 * NB: May drop and reacquire tty lock when blocking, so tty and tty_port
460 * may have changed state (eg., may have been hung up).
461 */
462int tty_port_block_til_ready(struct tty_port *port,
463 struct tty_struct *tty, struct file *filp)
464{
465 int do_clocal = 0, retval;
466 unsigned long flags;
467 DEFINE_WAIT(wait);
468
469 /* if non-blocking mode is set we can pass directly to open unless
470 the port has just hung up or is in another error state */
471 if (tty_io_error(tty)) {
472 tty_port_set_active(port, 1);
473 return 0;
474 }
475 if (filp == NULL || (filp->f_flags & O_NONBLOCK)) {
476 /* Indicate we are open */
477 if (C_BAUD(tty))
478 tty_port_raise_dtr_rts(port);
479 tty_port_set_active(port, 1);
480 return 0;
481 }
482
483 if (C_CLOCAL(tty))
484 do_clocal = 1;
485
486 /* Block waiting until we can proceed. We may need to wait for the
487 carrier, but we must also wait for any close that is in progress
488 before the next open may complete */
489
490 retval = 0;
491
492 /* The port lock protects the port counts */
493 spin_lock_irqsave(&port->lock, flags);
494 port->count--;
495 port->blocked_open++;
496 spin_unlock_irqrestore(&port->lock, flags);
497
498 while (1) {
499 /* Indicate we are open */
500 if (C_BAUD(tty) && tty_port_initialized(port))
501 tty_port_raise_dtr_rts(port);
502
503 prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
504 /* Check for a hangup or uninitialised port.
505 Return accordingly */
506 if (tty_hung_up_p(filp) || !tty_port_initialized(port)) {
507 if (port->flags & ASYNC_HUP_NOTIFY)
508 retval = -EAGAIN;
509 else
510 retval = -ERESTARTSYS;
511 break;
512 }
513 /*
514 * Probe the carrier. For devices with no carrier detect
515 * tty_port_carrier_raised will always return true.
516 * Never ask drivers if CLOCAL is set, this causes troubles
517 * on some hardware.
518 */
519 if (do_clocal || tty_port_carrier_raised(port))
520 break;
521 if (signal_pending(current)) {
522 retval = -ERESTARTSYS;
523 break;
524 }
525 tty_unlock(tty);
526 schedule();
527 tty_lock(tty);
528 }
529 finish_wait(&port->open_wait, &wait);
530
531 /* Update counts. A parallel hangup will have set count to zero and
532 we must not mess that up further */
533 spin_lock_irqsave(&port->lock, flags);
534 if (!tty_hung_up_p(filp))
535 port->count++;
536 port->blocked_open--;
537 spin_unlock_irqrestore(&port->lock, flags);
538 if (retval == 0)
539 tty_port_set_active(port, 1);
540 return retval;
541}
542EXPORT_SYMBOL(tty_port_block_til_ready);
543
544static void tty_port_drain_delay(struct tty_port *port, struct tty_struct *tty)
545{
546 unsigned int bps = tty_get_baud_rate(tty);
547 long timeout;
548
549 if (bps > 1200) {
550 timeout = (HZ * 10 * port->drain_delay) / bps;
551 timeout = max_t(long, timeout, HZ / 10);
552 } else {
553 timeout = 2 * HZ;
554 }
555 schedule_timeout_interruptible(timeout);
556}
557
558/* Caller holds tty lock. */
559int tty_port_close_start(struct tty_port *port,
560 struct tty_struct *tty, struct file *filp)
561{
562 unsigned long flags;
563
564 if (tty_hung_up_p(filp))
565 return 0;
566
567 spin_lock_irqsave(&port->lock, flags);
568 if (tty->count == 1 && port->count != 1) {
569 tty_warn(tty, "%s: tty->count = 1 port count = %d\n", __func__,
570 port->count);
571 port->count = 1;
572 }
573 if (--port->count < 0) {
574 tty_warn(tty, "%s: bad port count (%d)\n", __func__,
575 port->count);
576 port->count = 0;
577 }
578
579 if (port->count) {
580 spin_unlock_irqrestore(&port->lock, flags);
581 return 0;
582 }
583 spin_unlock_irqrestore(&port->lock, flags);
584
585 tty->closing = 1;
586
587 if (tty_port_initialized(port)) {
588 /* Don't block on a stalled port, just pull the chain */
589 if (tty->flow_stopped)
590 tty_driver_flush_buffer(tty);
591 if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
592 tty_wait_until_sent(tty, port->closing_wait);
593 if (port->drain_delay)
594 tty_port_drain_delay(port, tty);
595 }
596 /* Flush the ldisc buffering */
597 tty_ldisc_flush(tty);
598
599 /* Report to caller this is the last port reference */
600 return 1;
601}
602EXPORT_SYMBOL(tty_port_close_start);
603
604/* Caller holds tty lock */
605void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
606{
607 unsigned long flags;
608
609 tty_ldisc_flush(tty);
610 tty->closing = 0;
611
612 spin_lock_irqsave(&port->lock, flags);
613
614 if (port->blocked_open) {
615 spin_unlock_irqrestore(&port->lock, flags);
616 if (port->close_delay)
617 msleep_interruptible(jiffies_to_msecs(port->close_delay));
618 spin_lock_irqsave(&port->lock, flags);
619 wake_up_interruptible(&port->open_wait);
620 }
621 spin_unlock_irqrestore(&port->lock, flags);
622 tty_port_set_active(port, 0);
623}
624EXPORT_SYMBOL(tty_port_close_end);
625
626/**
627 * tty_port_close
628 *
629 * Caller holds tty lock
630 */
631void tty_port_close(struct tty_port *port, struct tty_struct *tty,
632 struct file *filp)
633{
634 if (tty_port_close_start(port, tty, filp) == 0)
635 return;
636 tty_port_shutdown(port, tty);
637 if (!port->console)
638 set_bit(TTY_IO_ERROR, &tty->flags);
639 tty_port_close_end(port, tty);
640 tty_port_tty_set(port, NULL);
641}
642EXPORT_SYMBOL(tty_port_close);
643
644/**
645 * tty_port_install - generic tty->ops->install handler
646 * @port: tty_port of the device
647 * @driver: tty_driver for this device
648 * @tty: tty to be installed
649 *
650 * It is the same as tty_standard_install except the provided @port is linked
651 * to a concrete tty specified by @tty. Use this or tty_port_register_device
652 * (or both). Call tty_port_link_device as a last resort.
653 */
654int tty_port_install(struct tty_port *port, struct tty_driver *driver,
655 struct tty_struct *tty)
656{
657 tty->port = port;
658 return tty_standard_install(driver, tty);
659}
660EXPORT_SYMBOL_GPL(tty_port_install);
661
662/**
663 * tty_port_open
664 *
665 * Caller holds tty lock.
666 *
667 * NB: may drop and reacquire tty lock (in tty_port_block_til_ready()) so
668 * tty and tty_port may have changed state (eg., may be hung up now)
669 */
670int tty_port_open(struct tty_port *port, struct tty_struct *tty,
671 struct file *filp)
672{
673 spin_lock_irq(&port->lock);
674 ++port->count;
675 spin_unlock_irq(&port->lock);
676 tty_port_tty_set(port, tty);
677
678 /*
679 * Do the device-specific open only if the hardware isn't
680 * already initialized. Serialize open and shutdown using the
681 * port mutex.
682 */
683
684 mutex_lock(&port->mutex);
685
686 if (!tty_port_initialized(port)) {
687 clear_bit(TTY_IO_ERROR, &tty->flags);
688 if (port->ops->activate) {
689 int retval = port->ops->activate(port, tty);
690 if (retval) {
691 mutex_unlock(&port->mutex);
692 return retval;
693 }
694 }
695 tty_port_set_initialized(port, 1);
696 }
697 mutex_unlock(&port->mutex);
698 return tty_port_block_til_ready(port, tty, filp);
699}
700
701EXPORT_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);