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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 int tty_port_default_receive_buf(struct tty_port *port,
24 const unsigned char *p,
25 const unsigned char *f, size_t count)
26{
27 int ret;
28 struct tty_struct *tty;
29 struct tty_ldisc *disc;
30
31 tty = READ_ONCE(port->itty);
32 if (!tty)
33 return 0;
34
35 disc = tty_ldisc_ref(tty);
36 if (!disc)
37 return 0;
38
39 ret = tty_ldisc_receive_buf(disc, p, (char *)f, count);
40
41 tty_ldisc_deref(disc);
42
43 return ret;
44}
45
46static void tty_port_default_lookahead_buf(struct tty_port *port, const unsigned char *p,
47 const unsigned char *f, unsigned int count)
48{
49 struct tty_struct *tty;
50 struct tty_ldisc *disc;
51
52 tty = READ_ONCE(port->itty);
53 if (!tty)
54 return;
55
56 disc = tty_ldisc_ref(tty);
57 if (!disc)
58 return;
59
60 if (disc->ops->lookahead_buf)
61 disc->ops->lookahead_buf(disc->tty, p, f, count);
62
63 tty_ldisc_deref(disc);
64}
65
66static void tty_port_default_wakeup(struct tty_port *port)
67{
68 struct tty_struct *tty = tty_port_tty_get(port);
69
70 if (tty) {
71 tty_wakeup(tty);
72 tty_kref_put(tty);
73 }
74}
75
76const struct tty_port_client_operations tty_port_default_client_ops = {
77 .receive_buf = tty_port_default_receive_buf,
78 .lookahead_buf = tty_port_default_lookahead_buf,
79 .write_wakeup = tty_port_default_wakeup,
80};
81EXPORT_SYMBOL_GPL(tty_port_default_client_ops);
82
83/**
84 * tty_port_init -- initialize tty_port
85 * @port: tty_port to initialize
86 *
87 * Initializes the state of struct tty_port. When a port was initialized using
88 * this function, one has to destroy the port by tty_port_destroy(). Either
89 * indirectly by using &tty_port refcounting (tty_port_put()) or directly if
90 * refcounting is not used.
91 */
92void tty_port_init(struct tty_port *port)
93{
94 memset(port, 0, sizeof(*port));
95 tty_buffer_init(port);
96 init_waitqueue_head(&port->open_wait);
97 init_waitqueue_head(&port->delta_msr_wait);
98 mutex_init(&port->mutex);
99 mutex_init(&port->buf_mutex);
100 spin_lock_init(&port->lock);
101 port->close_delay = (50 * HZ) / 100;
102 port->closing_wait = (3000 * HZ) / 100;
103 port->client_ops = &tty_port_default_client_ops;
104 kref_init(&port->kref);
105}
106EXPORT_SYMBOL(tty_port_init);
107
108/**
109 * tty_port_link_device - link tty and tty_port
110 * @port: tty_port of the device
111 * @driver: tty_driver for this device
112 * @index: index of the tty
113 *
114 * Provide the tty layer with a link from a tty (specified by @index) to a
115 * tty_port (@port). Use this only if neither tty_port_register_device() nor
116 * tty_port_install() is used in the driver. If used, this has to be called
117 * before tty_register_driver().
118 */
119void tty_port_link_device(struct tty_port *port,
120 struct tty_driver *driver, unsigned index)
121{
122 if (WARN_ON(index >= driver->num))
123 return;
124 driver->ports[index] = port;
125}
126EXPORT_SYMBOL_GPL(tty_port_link_device);
127
128/**
129 * tty_port_register_device - register tty device
130 * @port: tty_port of the device
131 * @driver: tty_driver for this device
132 * @index: index of the tty
133 * @device: parent if exists, otherwise NULL
134 *
135 * It is the same as tty_register_device() except the provided @port is linked
136 * to a concrete tty specified by @index. Use this or tty_port_install() (or
137 * both). Call tty_port_link_device() as a last resort.
138 */
139struct device *tty_port_register_device(struct tty_port *port,
140 struct tty_driver *driver, unsigned index,
141 struct device *device)
142{
143 return tty_port_register_device_attr(port, driver, index, device, NULL, NULL);
144}
145EXPORT_SYMBOL_GPL(tty_port_register_device);
146
147/**
148 * tty_port_register_device_attr - register tty device
149 * @port: tty_port of the device
150 * @driver: tty_driver for this device
151 * @index: index of the tty
152 * @device: parent if exists, otherwise NULL
153 * @drvdata: Driver data to be set to device.
154 * @attr_grp: Attribute group to be set on device.
155 *
156 * It is the same as tty_register_device_attr() except the provided @port is
157 * linked to a concrete tty specified by @index. Use this or tty_port_install()
158 * (or both). Call tty_port_link_device() as a last resort.
159 */
160struct device *tty_port_register_device_attr(struct tty_port *port,
161 struct tty_driver *driver, unsigned index,
162 struct device *device, void *drvdata,
163 const struct attribute_group **attr_grp)
164{
165 tty_port_link_device(port, driver, index);
166 return tty_register_device_attr(driver, index, device, drvdata,
167 attr_grp);
168}
169EXPORT_SYMBOL_GPL(tty_port_register_device_attr);
170
171/**
172 * tty_port_register_device_attr_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 * @drvdata: driver data for the device
178 * @attr_grp: attribute group for the device
179 *
180 * Register a serdev or tty device depending on if the parent device has any
181 * defined serdev clients or not.
182 */
183struct device *tty_port_register_device_attr_serdev(struct tty_port *port,
184 struct tty_driver *driver, unsigned index,
185 struct device *device, void *drvdata,
186 const struct attribute_group **attr_grp)
187{
188 struct device *dev;
189
190 tty_port_link_device(port, driver, index);
191
192 dev = serdev_tty_port_register(port, device, driver, index);
193 if (PTR_ERR(dev) != -ENODEV) {
194 /* Skip creating cdev if we registered a serdev device */
195 return dev;
196 }
197
198 return tty_register_device_attr(driver, index, device, drvdata,
199 attr_grp);
200}
201EXPORT_SYMBOL_GPL(tty_port_register_device_attr_serdev);
202
203/**
204 * tty_port_register_device_serdev - register tty or serdev device
205 * @port: tty_port of the device
206 * @driver: tty_driver for this device
207 * @index: index of the tty
208 * @device: 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 *device)
216{
217 return tty_port_register_device_attr_serdev(port, driver, index,
218 device, 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 = (unsigned char *)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, 0);
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, 0);
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 */
447int tty_port_carrier_raised(struct tty_port *port)
448{
449 if (port->ops->carrier_raised == NULL)
450 return 1;
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, 1);
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, 0);
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, 1);
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, 1);
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, 1);
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, 0);
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, 1);
792 }
793 mutex_unlock(&port->mutex);
794 return tty_port_block_til_ready(port, tty, filp);
795}
796EXPORT_SYMBOL(tty_port_open);
1/*
2 * Tty port functions
3 */
4
5#include <linux/types.h>
6#include <linux/errno.h>
7#include <linux/tty.h>
8#include <linux/tty_driver.h>
9#include <linux/tty_flip.h>
10#include <linux/serial.h>
11#include <linux/timer.h>
12#include <linux/string.h>
13#include <linux/slab.h>
14#include <linux/sched.h>
15#include <linux/wait.h>
16#include <linux/bitops.h>
17#include <linux/delay.h>
18#include <linux/module.h>
19
20void tty_port_init(struct tty_port *port)
21{
22 memset(port, 0, sizeof(*port));
23 tty_buffer_init(port);
24 init_waitqueue_head(&port->open_wait);
25 init_waitqueue_head(&port->delta_msr_wait);
26 mutex_init(&port->mutex);
27 mutex_init(&port->buf_mutex);
28 spin_lock_init(&port->lock);
29 port->close_delay = (50 * HZ) / 100;
30 port->closing_wait = (3000 * HZ) / 100;
31 kref_init(&port->kref);
32}
33EXPORT_SYMBOL(tty_port_init);
34
35/**
36 * tty_port_link_device - link tty and tty_port
37 * @port: tty_port of the device
38 * @driver: tty_driver for this device
39 * @index: index of the tty
40 *
41 * Provide the tty layer wit ha link from a tty (specified by @index) to a
42 * tty_port (@port). Use this only if neither tty_port_register_device nor
43 * tty_port_install is used in the driver. If used, this has to be called before
44 * tty_register_driver.
45 */
46void tty_port_link_device(struct tty_port *port,
47 struct tty_driver *driver, unsigned index)
48{
49 if (WARN_ON(index >= driver->num))
50 return;
51 driver->ports[index] = port;
52}
53EXPORT_SYMBOL_GPL(tty_port_link_device);
54
55/**
56 * tty_port_register_device - register tty device
57 * @port: tty_port of the device
58 * @driver: tty_driver for this device
59 * @index: index of the tty
60 * @device: parent if exists, otherwise NULL
61 *
62 * It is the same as tty_register_device except the provided @port is linked to
63 * a concrete tty specified by @index. Use this or tty_port_install (or both).
64 * Call tty_port_link_device as a last resort.
65 */
66struct device *tty_port_register_device(struct tty_port *port,
67 struct tty_driver *driver, unsigned index,
68 struct device *device)
69{
70 tty_port_link_device(port, driver, index);
71 return tty_register_device(driver, index, device);
72}
73EXPORT_SYMBOL_GPL(tty_port_register_device);
74
75/**
76 * tty_port_register_device_attr - register tty device
77 * @port: tty_port of the device
78 * @driver: tty_driver for this device
79 * @index: index of the tty
80 * @device: parent if exists, otherwise NULL
81 * @drvdata: Driver data to be set to device.
82 * @attr_grp: Attribute group to be set on device.
83 *
84 * It is the same as tty_register_device_attr except the provided @port is
85 * linked to a concrete tty specified by @index. Use this or tty_port_install
86 * (or both). Call tty_port_link_device as a last resort.
87 */
88struct device *tty_port_register_device_attr(struct tty_port *port,
89 struct tty_driver *driver, unsigned index,
90 struct device *device, void *drvdata,
91 const struct attribute_group **attr_grp)
92{
93 tty_port_link_device(port, driver, index);
94 return tty_register_device_attr(driver, index, device, drvdata,
95 attr_grp);
96}
97EXPORT_SYMBOL_GPL(tty_port_register_device_attr);
98
99int tty_port_alloc_xmit_buf(struct tty_port *port)
100{
101 /* We may sleep in get_zeroed_page() */
102 mutex_lock(&port->buf_mutex);
103 if (port->xmit_buf == NULL)
104 port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
105 mutex_unlock(&port->buf_mutex);
106 if (port->xmit_buf == NULL)
107 return -ENOMEM;
108 return 0;
109}
110EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
111
112void tty_port_free_xmit_buf(struct tty_port *port)
113{
114 mutex_lock(&port->buf_mutex);
115 if (port->xmit_buf != NULL) {
116 free_page((unsigned long)port->xmit_buf);
117 port->xmit_buf = NULL;
118 }
119 mutex_unlock(&port->buf_mutex);
120}
121EXPORT_SYMBOL(tty_port_free_xmit_buf);
122
123/**
124 * tty_port_destroy -- destroy inited port
125 * @port: tty port to be doestroyed
126 *
127 * When a port was initialized using tty_port_init, one has to destroy the
128 * port by this function. Either indirectly by using tty_port refcounting
129 * (tty_port_put) or directly if refcounting is not used.
130 */
131void tty_port_destroy(struct tty_port *port)
132{
133 tty_buffer_cancel_work(port);
134 tty_buffer_free_all(port);
135}
136EXPORT_SYMBOL(tty_port_destroy);
137
138static void tty_port_destructor(struct kref *kref)
139{
140 struct tty_port *port = container_of(kref, struct tty_port, kref);
141
142 /* check if last port ref was dropped before tty release */
143 if (WARN_ON(port->itty))
144 return;
145 if (port->xmit_buf)
146 free_page((unsigned long)port->xmit_buf);
147 tty_port_destroy(port);
148 if (port->ops && port->ops->destruct)
149 port->ops->destruct(port);
150 else
151 kfree(port);
152}
153
154void tty_port_put(struct tty_port *port)
155{
156 if (port)
157 kref_put(&port->kref, tty_port_destructor);
158}
159EXPORT_SYMBOL(tty_port_put);
160
161/**
162 * tty_port_tty_get - get a tty reference
163 * @port: tty port
164 *
165 * Return a refcount protected tty instance or NULL if the port is not
166 * associated with a tty (eg due to close or hangup)
167 */
168
169struct tty_struct *tty_port_tty_get(struct tty_port *port)
170{
171 unsigned long flags;
172 struct tty_struct *tty;
173
174 spin_lock_irqsave(&port->lock, flags);
175 tty = tty_kref_get(port->tty);
176 spin_unlock_irqrestore(&port->lock, flags);
177 return tty;
178}
179EXPORT_SYMBOL(tty_port_tty_get);
180
181/**
182 * tty_port_tty_set - set the tty of a port
183 * @port: tty port
184 * @tty: the tty
185 *
186 * Associate the port and tty pair. Manages any internal refcounts.
187 * Pass NULL to deassociate a port
188 */
189
190void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
191{
192 unsigned long flags;
193
194 spin_lock_irqsave(&port->lock, flags);
195 tty_kref_put(port->tty);
196 port->tty = tty_kref_get(tty);
197 spin_unlock_irqrestore(&port->lock, flags);
198}
199EXPORT_SYMBOL(tty_port_tty_set);
200
201static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty)
202{
203 mutex_lock(&port->mutex);
204 if (port->console)
205 goto out;
206
207 if (tty_port_initialized(port)) {
208 tty_port_set_initialized(port, 0);
209 /*
210 * Drop DTR/RTS if HUPCL is set. This causes any attached
211 * modem to hang up the line.
212 */
213 if (tty && C_HUPCL(tty))
214 tty_port_lower_dtr_rts(port);
215
216 if (port->ops->shutdown)
217 port->ops->shutdown(port);
218 }
219out:
220 mutex_unlock(&port->mutex);
221}
222
223/**
224 * tty_port_hangup - hangup helper
225 * @port: tty port
226 *
227 * Perform port level tty hangup flag and count changes. Drop the tty
228 * reference.
229 *
230 * Caller holds tty lock.
231 */
232
233void tty_port_hangup(struct tty_port *port)
234{
235 struct tty_struct *tty;
236 unsigned long flags;
237
238 spin_lock_irqsave(&port->lock, flags);
239 port->count = 0;
240 tty = port->tty;
241 if (tty)
242 set_bit(TTY_IO_ERROR, &tty->flags);
243 port->tty = NULL;
244 spin_unlock_irqrestore(&port->lock, flags);
245 tty_port_set_active(port, 0);
246 tty_port_shutdown(port, tty);
247 tty_kref_put(tty);
248 wake_up_interruptible(&port->open_wait);
249 wake_up_interruptible(&port->delta_msr_wait);
250}
251EXPORT_SYMBOL(tty_port_hangup);
252
253/**
254 * tty_port_tty_hangup - helper to hang up a tty
255 *
256 * @port: tty port
257 * @check_clocal: hang only ttys with CLOCAL unset?
258 */
259void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
260{
261 struct tty_struct *tty = tty_port_tty_get(port);
262
263 if (tty && (!check_clocal || !C_CLOCAL(tty)))
264 tty_hangup(tty);
265 tty_kref_put(tty);
266}
267EXPORT_SYMBOL_GPL(tty_port_tty_hangup);
268
269/**
270 * tty_port_tty_wakeup - helper to wake up a tty
271 *
272 * @port: tty port
273 */
274void tty_port_tty_wakeup(struct tty_port *port)
275{
276 struct tty_struct *tty = tty_port_tty_get(port);
277
278 if (tty) {
279 tty_wakeup(tty);
280 tty_kref_put(tty);
281 }
282}
283EXPORT_SYMBOL_GPL(tty_port_tty_wakeup);
284
285/**
286 * tty_port_carrier_raised - carrier raised check
287 * @port: tty port
288 *
289 * Wrapper for the carrier detect logic. For the moment this is used
290 * to hide some internal details. This will eventually become entirely
291 * internal to the tty port.
292 */
293
294int tty_port_carrier_raised(struct tty_port *port)
295{
296 if (port->ops->carrier_raised == NULL)
297 return 1;
298 return port->ops->carrier_raised(port);
299}
300EXPORT_SYMBOL(tty_port_carrier_raised);
301
302/**
303 * tty_port_raise_dtr_rts - Raise DTR/RTS
304 * @port: tty port
305 *
306 * Wrapper for the DTR/RTS raise logic. For the moment this is used
307 * to hide some internal details. This will eventually become entirely
308 * internal to the tty port.
309 */
310
311void tty_port_raise_dtr_rts(struct tty_port *port)
312{
313 if (port->ops->dtr_rts)
314 port->ops->dtr_rts(port, 1);
315}
316EXPORT_SYMBOL(tty_port_raise_dtr_rts);
317
318/**
319 * tty_port_lower_dtr_rts - Lower DTR/RTS
320 * @port: tty port
321 *
322 * Wrapper for the DTR/RTS raise logic. For the moment this is used
323 * to hide some internal details. This will eventually become entirely
324 * internal to the tty port.
325 */
326
327void tty_port_lower_dtr_rts(struct tty_port *port)
328{
329 if (port->ops->dtr_rts)
330 port->ops->dtr_rts(port, 0);
331}
332EXPORT_SYMBOL(tty_port_lower_dtr_rts);
333
334/**
335 * tty_port_block_til_ready - Waiting logic for tty open
336 * @port: the tty port being opened
337 * @tty: the tty device being bound
338 * @filp: the file pointer of the opener
339 *
340 * Implement the core POSIX/SuS tty behaviour when opening a tty device.
341 * Handles:
342 * - hangup (both before and during)
343 * - non blocking open
344 * - rts/dtr/dcd
345 * - signals
346 * - port flags and counts
347 *
348 * The passed tty_port must implement the carrier_raised method if it can
349 * do carrier detect and the dtr_rts method if it supports software
350 * management of these lines. Note that the dtr/rts raise is done each
351 * iteration as a hangup may have previously dropped them while we wait.
352 *
353 * Caller holds tty lock.
354 *
355 * NB: May drop and reacquire tty lock when blocking, so tty and tty_port
356 * may have changed state (eg., may have been hung up).
357 */
358
359int tty_port_block_til_ready(struct tty_port *port,
360 struct tty_struct *tty, struct file *filp)
361{
362 int do_clocal = 0, retval;
363 unsigned long flags;
364 DEFINE_WAIT(wait);
365
366 /* if non-blocking mode is set we can pass directly to open unless
367 the port has just hung up or is in another error state */
368 if (tty_io_error(tty)) {
369 tty_port_set_active(port, 1);
370 return 0;
371 }
372 if (filp->f_flags & O_NONBLOCK) {
373 /* Indicate we are open */
374 if (C_BAUD(tty))
375 tty_port_raise_dtr_rts(port);
376 tty_port_set_active(port, 1);
377 return 0;
378 }
379
380 if (C_CLOCAL(tty))
381 do_clocal = 1;
382
383 /* Block waiting until we can proceed. We may need to wait for the
384 carrier, but we must also wait for any close that is in progress
385 before the next open may complete */
386
387 retval = 0;
388
389 /* The port lock protects the port counts */
390 spin_lock_irqsave(&port->lock, flags);
391 port->count--;
392 port->blocked_open++;
393 spin_unlock_irqrestore(&port->lock, flags);
394
395 while (1) {
396 /* Indicate we are open */
397 if (C_BAUD(tty) && tty_port_initialized(port))
398 tty_port_raise_dtr_rts(port);
399
400 prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
401 /* Check for a hangup or uninitialised port.
402 Return accordingly */
403 if (tty_hung_up_p(filp) || !tty_port_initialized(port)) {
404 if (port->flags & ASYNC_HUP_NOTIFY)
405 retval = -EAGAIN;
406 else
407 retval = -ERESTARTSYS;
408 break;
409 }
410 /*
411 * Probe the carrier. For devices with no carrier detect
412 * tty_port_carrier_raised will always return true.
413 * Never ask drivers if CLOCAL is set, this causes troubles
414 * on some hardware.
415 */
416 if (do_clocal || tty_port_carrier_raised(port))
417 break;
418 if (signal_pending(current)) {
419 retval = -ERESTARTSYS;
420 break;
421 }
422 tty_unlock(tty);
423 schedule();
424 tty_lock(tty);
425 }
426 finish_wait(&port->open_wait, &wait);
427
428 /* Update counts. A parallel hangup will have set count to zero and
429 we must not mess that up further */
430 spin_lock_irqsave(&port->lock, flags);
431 if (!tty_hung_up_p(filp))
432 port->count++;
433 port->blocked_open--;
434 spin_unlock_irqrestore(&port->lock, flags);
435 if (retval == 0)
436 tty_port_set_active(port, 1);
437 return retval;
438}
439EXPORT_SYMBOL(tty_port_block_til_ready);
440
441static void tty_port_drain_delay(struct tty_port *port, struct tty_struct *tty)
442{
443 unsigned int bps = tty_get_baud_rate(tty);
444 long timeout;
445
446 if (bps > 1200) {
447 timeout = (HZ * 10 * port->drain_delay) / bps;
448 timeout = max_t(long, timeout, HZ / 10);
449 } else {
450 timeout = 2 * HZ;
451 }
452 schedule_timeout_interruptible(timeout);
453}
454
455/* Caller holds tty lock. */
456int tty_port_close_start(struct tty_port *port,
457 struct tty_struct *tty, struct file *filp)
458{
459 unsigned long flags;
460
461 if (tty_hung_up_p(filp))
462 return 0;
463
464 spin_lock_irqsave(&port->lock, flags);
465 if (tty->count == 1 && port->count != 1) {
466 tty_warn(tty, "%s: tty->count = 1 port count = %d\n", __func__,
467 port->count);
468 port->count = 1;
469 }
470 if (--port->count < 0) {
471 tty_warn(tty, "%s: bad port count (%d)\n", __func__,
472 port->count);
473 port->count = 0;
474 }
475
476 if (port->count) {
477 spin_unlock_irqrestore(&port->lock, flags);
478 return 0;
479 }
480 spin_unlock_irqrestore(&port->lock, flags);
481
482 tty->closing = 1;
483
484 if (tty_port_initialized(port)) {
485 /* Don't block on a stalled port, just pull the chain */
486 if (tty->flow_stopped)
487 tty_driver_flush_buffer(tty);
488 if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
489 tty_wait_until_sent(tty, port->closing_wait);
490 if (port->drain_delay)
491 tty_port_drain_delay(port, tty);
492 }
493 /* Flush the ldisc buffering */
494 tty_ldisc_flush(tty);
495
496 /* Report to caller this is the last port reference */
497 return 1;
498}
499EXPORT_SYMBOL(tty_port_close_start);
500
501/* Caller holds tty lock */
502void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
503{
504 unsigned long flags;
505
506 tty_ldisc_flush(tty);
507 tty->closing = 0;
508
509 spin_lock_irqsave(&port->lock, flags);
510
511 if (port->blocked_open) {
512 spin_unlock_irqrestore(&port->lock, flags);
513 if (port->close_delay)
514 msleep_interruptible(jiffies_to_msecs(port->close_delay));
515 spin_lock_irqsave(&port->lock, flags);
516 wake_up_interruptible(&port->open_wait);
517 }
518 spin_unlock_irqrestore(&port->lock, flags);
519 tty_port_set_active(port, 0);
520}
521EXPORT_SYMBOL(tty_port_close_end);
522
523/**
524 * tty_port_close
525 *
526 * Caller holds tty lock
527 */
528void tty_port_close(struct tty_port *port, struct tty_struct *tty,
529 struct file *filp)
530{
531 if (tty_port_close_start(port, tty, filp) == 0)
532 return;
533 tty_port_shutdown(port, tty);
534 set_bit(TTY_IO_ERROR, &tty->flags);
535 tty_port_close_end(port, tty);
536 tty_port_tty_set(port, NULL);
537}
538EXPORT_SYMBOL(tty_port_close);
539
540/**
541 * tty_port_install - generic tty->ops->install handler
542 * @port: tty_port of the device
543 * @driver: tty_driver for this device
544 * @tty: tty to be installed
545 *
546 * It is the same as tty_standard_install except the provided @port is linked
547 * to a concrete tty specified by @tty. Use this or tty_port_register_device
548 * (or both). Call tty_port_link_device as a last resort.
549 */
550int tty_port_install(struct tty_port *port, struct tty_driver *driver,
551 struct tty_struct *tty)
552{
553 tty->port = port;
554 return tty_standard_install(driver, tty);
555}
556EXPORT_SYMBOL_GPL(tty_port_install);
557
558/**
559 * tty_port_open
560 *
561 * Caller holds tty lock.
562 *
563 * NB: may drop and reacquire tty lock (in tty_port_block_til_ready()) so
564 * tty and tty_port may have changed state (eg., may be hung up now)
565 */
566int tty_port_open(struct tty_port *port, struct tty_struct *tty,
567 struct file *filp)
568{
569 spin_lock_irq(&port->lock);
570 ++port->count;
571 spin_unlock_irq(&port->lock);
572 tty_port_tty_set(port, tty);
573
574 /*
575 * Do the device-specific open only if the hardware isn't
576 * already initialized. Serialize open and shutdown using the
577 * port mutex.
578 */
579
580 mutex_lock(&port->mutex);
581
582 if (!tty_port_initialized(port)) {
583 clear_bit(TTY_IO_ERROR, &tty->flags);
584 if (port->ops->activate) {
585 int retval = port->ops->activate(port, tty);
586 if (retval) {
587 mutex_unlock(&port->mutex);
588 return retval;
589 }
590 }
591 tty_port_set_initialized(port, 1);
592 }
593 mutex_unlock(&port->mutex);
594 return tty_port_block_til_ready(port, tty, filp);
595}
596
597EXPORT_SYMBOL(tty_port_open);