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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/*
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 (test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags)) {
208 /*
209 * Drop DTR/RTS if HUPCL is set. This causes any attached
210 * modem to hang up the line.
211 */
212 if (tty && C_HUPCL(tty))
213 tty_port_lower_dtr_rts(port);
214
215 if (port->ops->shutdown)
216 port->ops->shutdown(port);
217 }
218out:
219 mutex_unlock(&port->mutex);
220}
221
222/**
223 * tty_port_hangup - hangup helper
224 * @port: tty port
225 *
226 * Perform port level tty hangup flag and count changes. Drop the tty
227 * reference.
228 *
229 * Caller holds tty lock.
230 */
231
232void tty_port_hangup(struct tty_port *port)
233{
234 struct tty_struct *tty;
235 unsigned long flags;
236
237 spin_lock_irqsave(&port->lock, flags);
238 port->count = 0;
239 port->flags &= ~ASYNC_NORMAL_ACTIVE;
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_shutdown(port, tty);
246 tty_kref_put(tty);
247 wake_up_interruptible(&port->open_wait);
248 wake_up_interruptible(&port->delta_msr_wait);
249}
250EXPORT_SYMBOL(tty_port_hangup);
251
252/**
253 * tty_port_tty_hangup - helper to hang up a tty
254 *
255 * @port: tty port
256 * @check_clocal: hang only ttys with CLOCAL unset?
257 */
258void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
259{
260 struct tty_struct *tty = tty_port_tty_get(port);
261
262 if (tty && (!check_clocal || !C_CLOCAL(tty)))
263 tty_hangup(tty);
264 tty_kref_put(tty);
265}
266EXPORT_SYMBOL_GPL(tty_port_tty_hangup);
267
268/**
269 * tty_port_tty_wakeup - helper to wake up a tty
270 *
271 * @port: tty port
272 */
273void tty_port_tty_wakeup(struct tty_port *port)
274{
275 struct tty_struct *tty = tty_port_tty_get(port);
276
277 if (tty) {
278 tty_wakeup(tty);
279 tty_kref_put(tty);
280 }
281}
282EXPORT_SYMBOL_GPL(tty_port_tty_wakeup);
283
284/**
285 * tty_port_carrier_raised - carrier raised check
286 * @port: tty port
287 *
288 * Wrapper for the carrier detect logic. For the moment this is used
289 * to hide some internal details. This will eventually become entirely
290 * internal to the tty port.
291 */
292
293int tty_port_carrier_raised(struct tty_port *port)
294{
295 if (port->ops->carrier_raised == NULL)
296 return 1;
297 return port->ops->carrier_raised(port);
298}
299EXPORT_SYMBOL(tty_port_carrier_raised);
300
301/**
302 * tty_port_raise_dtr_rts - Raise DTR/RTS
303 * @port: tty port
304 *
305 * Wrapper for the DTR/RTS raise logic. For the moment this is used
306 * to hide some internal details. This will eventually become entirely
307 * internal to the tty port.
308 */
309
310void tty_port_raise_dtr_rts(struct tty_port *port)
311{
312 if (port->ops->dtr_rts)
313 port->ops->dtr_rts(port, 1);
314}
315EXPORT_SYMBOL(tty_port_raise_dtr_rts);
316
317/**
318 * tty_port_lower_dtr_rts - Lower DTR/RTS
319 * @port: tty port
320 *
321 * Wrapper for the DTR/RTS raise logic. For the moment this is used
322 * to hide some internal details. This will eventually become entirely
323 * internal to the tty port.
324 */
325
326void tty_port_lower_dtr_rts(struct tty_port *port)
327{
328 if (port->ops->dtr_rts)
329 port->ops->dtr_rts(port, 0);
330}
331EXPORT_SYMBOL(tty_port_lower_dtr_rts);
332
333/**
334 * tty_port_block_til_ready - Waiting logic for tty open
335 * @port: the tty port being opened
336 * @tty: the tty device being bound
337 * @filp: the file pointer of the opener
338 *
339 * Implement the core POSIX/SuS tty behaviour when opening a tty device.
340 * Handles:
341 * - hangup (both before and during)
342 * - non blocking open
343 * - rts/dtr/dcd
344 * - signals
345 * - port flags and counts
346 *
347 * The passed tty_port must implement the carrier_raised method if it can
348 * do carrier detect and the dtr_rts method if it supports software
349 * management of these lines. Note that the dtr/rts raise is done each
350 * iteration as a hangup may have previously dropped them while we wait.
351 *
352 * Caller holds tty lock.
353 *
354 * NB: May drop and reacquire tty lock when blocking, so tty and tty_port
355 * may have changed state (eg., may have been hung up).
356 */
357
358int tty_port_block_til_ready(struct tty_port *port,
359 struct tty_struct *tty, struct file *filp)
360{
361 int do_clocal = 0, retval;
362 unsigned long flags;
363 DEFINE_WAIT(wait);
364
365 /* if non-blocking mode is set we can pass directly to open unless
366 the port has just hung up or is in another error state */
367 if (tty->flags & (1 << TTY_IO_ERROR)) {
368 port->flags |= ASYNC_NORMAL_ACTIVE;
369 return 0;
370 }
371 if (filp->f_flags & O_NONBLOCK) {
372 /* Indicate we are open */
373 if (C_BAUD(tty))
374 tty_port_raise_dtr_rts(port);
375 port->flags |= ASYNC_NORMAL_ACTIVE;
376 return 0;
377 }
378
379 if (C_CLOCAL(tty))
380 do_clocal = 1;
381
382 /* Block waiting until we can proceed. We may need to wait for the
383 carrier, but we must also wait for any close that is in progress
384 before the next open may complete */
385
386 retval = 0;
387
388 /* The port lock protects the port counts */
389 spin_lock_irqsave(&port->lock, flags);
390 port->count--;
391 port->blocked_open++;
392 spin_unlock_irqrestore(&port->lock, flags);
393
394 while (1) {
395 /* Indicate we are open */
396 if (C_BAUD(tty) && test_bit(ASYNCB_INITIALIZED, &port->flags))
397 tty_port_raise_dtr_rts(port);
398
399 prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
400 /* Check for a hangup or uninitialised port.
401 Return accordingly */
402 if (tty_hung_up_p(filp) || !(port->flags & ASYNC_INITIALIZED)) {
403 if (port->flags & ASYNC_HUP_NOTIFY)
404 retval = -EAGAIN;
405 else
406 retval = -ERESTARTSYS;
407 break;
408 }
409 /*
410 * Probe the carrier. For devices with no carrier detect
411 * tty_port_carrier_raised will always return true.
412 * Never ask drivers if CLOCAL is set, this causes troubles
413 * on some hardware.
414 */
415 if (do_clocal || tty_port_carrier_raised(port))
416 break;
417 if (signal_pending(current)) {
418 retval = -ERESTARTSYS;
419 break;
420 }
421 tty_unlock(tty);
422 schedule();
423 tty_lock(tty);
424 }
425 finish_wait(&port->open_wait, &wait);
426
427 /* Update counts. A parallel hangup will have set count to zero and
428 we must not mess that up further */
429 spin_lock_irqsave(&port->lock, flags);
430 if (!tty_hung_up_p(filp))
431 port->count++;
432 port->blocked_open--;
433 if (retval == 0)
434 port->flags |= ASYNC_NORMAL_ACTIVE;
435 spin_unlock_irqrestore(&port->lock, flags);
436 return retval;
437}
438EXPORT_SYMBOL(tty_port_block_til_ready);
439
440static void tty_port_drain_delay(struct tty_port *port, struct tty_struct *tty)
441{
442 unsigned int bps = tty_get_baud_rate(tty);
443 long timeout;
444
445 if (bps > 1200) {
446 timeout = (HZ * 10 * port->drain_delay) / bps;
447 timeout = max_t(long, timeout, HZ / 10);
448 } else {
449 timeout = 2 * HZ;
450 }
451 schedule_timeout_interruptible(timeout);
452}
453
454/* Caller holds tty lock. */
455int tty_port_close_start(struct tty_port *port,
456 struct tty_struct *tty, struct file *filp)
457{
458 unsigned long flags;
459
460 if (tty_hung_up_p(filp))
461 return 0;
462
463 spin_lock_irqsave(&port->lock, flags);
464 if (tty->count == 1 && port->count != 1) {
465 tty_warn(tty, "%s: tty->count = 1 port count = %d\n", __func__,
466 port->count);
467 port->count = 1;
468 }
469 if (--port->count < 0) {
470 tty_warn(tty, "%s: bad port count (%d)\n", __func__,
471 port->count);
472 port->count = 0;
473 }
474
475 if (port->count) {
476 spin_unlock_irqrestore(&port->lock, flags);
477 return 0;
478 }
479 spin_unlock_irqrestore(&port->lock, flags);
480
481 tty->closing = 1;
482
483 if (test_bit(ASYNCB_INITIALIZED, &port->flags)) {
484 /* Don't block on a stalled port, just pull the chain */
485 if (tty->flow_stopped)
486 tty_driver_flush_buffer(tty);
487 if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
488 tty_wait_until_sent(tty, port->closing_wait);
489 if (port->drain_delay)
490 tty_port_drain_delay(port, tty);
491 }
492 /* Flush the ldisc buffering */
493 tty_ldisc_flush(tty);
494
495 /* Report to caller this is the last port reference */
496 return 1;
497}
498EXPORT_SYMBOL(tty_port_close_start);
499
500/* Caller holds tty lock */
501void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
502{
503 unsigned long flags;
504
505 tty_ldisc_flush(tty);
506 tty->closing = 0;
507
508 spin_lock_irqsave(&port->lock, flags);
509
510 if (port->blocked_open) {
511 spin_unlock_irqrestore(&port->lock, flags);
512 if (port->close_delay)
513 msleep_interruptible(jiffies_to_msecs(port->close_delay));
514 spin_lock_irqsave(&port->lock, flags);
515 wake_up_interruptible(&port->open_wait);
516 }
517 port->flags &= ~ASYNC_NORMAL_ACTIVE;
518 spin_unlock_irqrestore(&port->lock, flags);
519}
520EXPORT_SYMBOL(tty_port_close_end);
521
522/**
523 * tty_port_close
524 *
525 * Caller holds tty lock
526 */
527void tty_port_close(struct tty_port *port, struct tty_struct *tty,
528 struct file *filp)
529{
530 if (tty_port_close_start(port, tty, filp) == 0)
531 return;
532 tty_port_shutdown(port, tty);
533 set_bit(TTY_IO_ERROR, &tty->flags);
534 tty_port_close_end(port, tty);
535 tty_port_tty_set(port, NULL);
536}
537EXPORT_SYMBOL(tty_port_close);
538
539/**
540 * tty_port_install - generic tty->ops->install handler
541 * @port: tty_port of the device
542 * @driver: tty_driver for this device
543 * @tty: tty to be installed
544 *
545 * It is the same as tty_standard_install except the provided @port is linked
546 * to a concrete tty specified by @tty. Use this or tty_port_register_device
547 * (or both). Call tty_port_link_device as a last resort.
548 */
549int tty_port_install(struct tty_port *port, struct tty_driver *driver,
550 struct tty_struct *tty)
551{
552 tty->port = port;
553 return tty_standard_install(driver, tty);
554}
555EXPORT_SYMBOL_GPL(tty_port_install);
556
557/**
558 * tty_port_open
559 *
560 * Caller holds tty lock.
561 *
562 * NB: may drop and reacquire tty lock (in tty_port_block_til_ready()) so
563 * tty and tty_port may have changed state (eg., may be hung up now)
564 */
565int tty_port_open(struct tty_port *port, struct tty_struct *tty,
566 struct file *filp)
567{
568 spin_lock_irq(&port->lock);
569 ++port->count;
570 spin_unlock_irq(&port->lock);
571 tty_port_tty_set(port, tty);
572
573 /*
574 * Do the device-specific open only if the hardware isn't
575 * already initialized. Serialize open and shutdown using the
576 * port mutex.
577 */
578
579 mutex_lock(&port->mutex);
580
581 if (!test_bit(ASYNCB_INITIALIZED, &port->flags)) {
582 clear_bit(TTY_IO_ERROR, &tty->flags);
583 if (port->ops->activate) {
584 int retval = port->ops->activate(port, tty);
585 if (retval) {
586 mutex_unlock(&port->mutex);
587 return retval;
588 }
589 }
590 set_bit(ASYNCB_INITIALIZED, &port->flags);
591 }
592 mutex_unlock(&port->mutex);
593 return tty_port_block_til_ready(port, tty, filp);
594}
595
596EXPORT_SYMBOL(tty_port_open);