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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/init.h>
16#include <linux/wait.h>
17#include <linux/bitops.h>
18#include <linux/delay.h>
19#include <linux/module.h>
20
21void tty_port_init(struct tty_port *port)
22{
23 memset(port, 0, sizeof(*port));
24 init_waitqueue_head(&port->open_wait);
25 init_waitqueue_head(&port->close_wait);
26 init_waitqueue_head(&port->delta_msr_wait);
27 mutex_init(&port->mutex);
28 mutex_init(&port->buf_mutex);
29 spin_lock_init(&port->lock);
30 port->close_delay = (50 * HZ) / 100;
31 port->closing_wait = (3000 * HZ) / 100;
32 kref_init(&port->kref);
33}
34EXPORT_SYMBOL(tty_port_init);
35
36int tty_port_alloc_xmit_buf(struct tty_port *port)
37{
38 /* We may sleep in get_zeroed_page() */
39 mutex_lock(&port->buf_mutex);
40 if (port->xmit_buf == NULL)
41 port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
42 mutex_unlock(&port->buf_mutex);
43 if (port->xmit_buf == NULL)
44 return -ENOMEM;
45 return 0;
46}
47EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
48
49void tty_port_free_xmit_buf(struct tty_port *port)
50{
51 mutex_lock(&port->buf_mutex);
52 if (port->xmit_buf != NULL) {
53 free_page((unsigned long)port->xmit_buf);
54 port->xmit_buf = NULL;
55 }
56 mutex_unlock(&port->buf_mutex);
57}
58EXPORT_SYMBOL(tty_port_free_xmit_buf);
59
60static void tty_port_destructor(struct kref *kref)
61{
62 struct tty_port *port = container_of(kref, struct tty_port, kref);
63 if (port->xmit_buf)
64 free_page((unsigned long)port->xmit_buf);
65 if (port->ops->destruct)
66 port->ops->destruct(port);
67 else
68 kfree(port);
69}
70
71void tty_port_put(struct tty_port *port)
72{
73 if (port)
74 kref_put(&port->kref, tty_port_destructor);
75}
76EXPORT_SYMBOL(tty_port_put);
77
78/**
79 * tty_port_tty_get - get a tty reference
80 * @port: tty port
81 *
82 * Return a refcount protected tty instance or NULL if the port is not
83 * associated with a tty (eg due to close or hangup)
84 */
85
86struct tty_struct *tty_port_tty_get(struct tty_port *port)
87{
88 unsigned long flags;
89 struct tty_struct *tty;
90
91 spin_lock_irqsave(&port->lock, flags);
92 tty = tty_kref_get(port->tty);
93 spin_unlock_irqrestore(&port->lock, flags);
94 return tty;
95}
96EXPORT_SYMBOL(tty_port_tty_get);
97
98/**
99 * tty_port_tty_set - set the tty of a port
100 * @port: tty port
101 * @tty: the tty
102 *
103 * Associate the port and tty pair. Manages any internal refcounts.
104 * Pass NULL to deassociate a port
105 */
106
107void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
108{
109 unsigned long flags;
110
111 spin_lock_irqsave(&port->lock, flags);
112 if (port->tty)
113 tty_kref_put(port->tty);
114 port->tty = tty_kref_get(tty);
115 spin_unlock_irqrestore(&port->lock, flags);
116}
117EXPORT_SYMBOL(tty_port_tty_set);
118
119static void tty_port_shutdown(struct tty_port *port)
120{
121 mutex_lock(&port->mutex);
122 if (port->ops->shutdown && !port->console &&
123 test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags))
124 port->ops->shutdown(port);
125 mutex_unlock(&port->mutex);
126}
127
128/**
129 * tty_port_hangup - hangup helper
130 * @port: tty port
131 *
132 * Perform port level tty hangup flag and count changes. Drop the tty
133 * reference.
134 */
135
136void tty_port_hangup(struct tty_port *port)
137{
138 unsigned long flags;
139
140 spin_lock_irqsave(&port->lock, flags);
141 port->count = 0;
142 port->flags &= ~ASYNC_NORMAL_ACTIVE;
143 if (port->tty) {
144 set_bit(TTY_IO_ERROR, &port->tty->flags);
145 tty_kref_put(port->tty);
146 }
147 port->tty = NULL;
148 spin_unlock_irqrestore(&port->lock, flags);
149 wake_up_interruptible(&port->open_wait);
150 wake_up_interruptible(&port->delta_msr_wait);
151 tty_port_shutdown(port);
152}
153EXPORT_SYMBOL(tty_port_hangup);
154
155/**
156 * tty_port_carrier_raised - carrier raised check
157 * @port: tty port
158 *
159 * Wrapper for the carrier detect logic. For the moment this is used
160 * to hide some internal details. This will eventually become entirely
161 * internal to the tty port.
162 */
163
164int tty_port_carrier_raised(struct tty_port *port)
165{
166 if (port->ops->carrier_raised == NULL)
167 return 1;
168 return port->ops->carrier_raised(port);
169}
170EXPORT_SYMBOL(tty_port_carrier_raised);
171
172/**
173 * tty_port_raise_dtr_rts - Raise DTR/RTS
174 * @port: tty port
175 *
176 * Wrapper for the DTR/RTS raise logic. For the moment this is used
177 * to hide some internal details. This will eventually become entirely
178 * internal to the tty port.
179 */
180
181void tty_port_raise_dtr_rts(struct tty_port *port)
182{
183 if (port->ops->dtr_rts)
184 port->ops->dtr_rts(port, 1);
185}
186EXPORT_SYMBOL(tty_port_raise_dtr_rts);
187
188/**
189 * tty_port_lower_dtr_rts - Lower DTR/RTS
190 * @port: tty port
191 *
192 * Wrapper for the DTR/RTS raise logic. For the moment this is used
193 * to hide some internal details. This will eventually become entirely
194 * internal to the tty port.
195 */
196
197void tty_port_lower_dtr_rts(struct tty_port *port)
198{
199 if (port->ops->dtr_rts)
200 port->ops->dtr_rts(port, 0);
201}
202EXPORT_SYMBOL(tty_port_lower_dtr_rts);
203
204/**
205 * tty_port_block_til_ready - Waiting logic for tty open
206 * @port: the tty port being opened
207 * @tty: the tty device being bound
208 * @filp: the file pointer of the opener
209 *
210 * Implement the core POSIX/SuS tty behaviour when opening a tty device.
211 * Handles:
212 * - hangup (both before and during)
213 * - non blocking open
214 * - rts/dtr/dcd
215 * - signals
216 * - port flags and counts
217 *
218 * The passed tty_port must implement the carrier_raised method if it can
219 * do carrier detect and the dtr_rts method if it supports software
220 * management of these lines. Note that the dtr/rts raise is done each
221 * iteration as a hangup may have previously dropped them while we wait.
222 */
223
224int tty_port_block_til_ready(struct tty_port *port,
225 struct tty_struct *tty, struct file *filp)
226{
227 int do_clocal = 0, retval;
228 unsigned long flags;
229 DEFINE_WAIT(wait);
230
231 /* block if port is in the process of being closed */
232 if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
233 wait_event_interruptible_tty(port->close_wait,
234 !(port->flags & ASYNC_CLOSING));
235 if (port->flags & ASYNC_HUP_NOTIFY)
236 return -EAGAIN;
237 else
238 return -ERESTARTSYS;
239 }
240
241 /* if non-blocking mode is set we can pass directly to open unless
242 the port has just hung up or is in another error state */
243 if (tty->flags & (1 << TTY_IO_ERROR)) {
244 port->flags |= ASYNC_NORMAL_ACTIVE;
245 return 0;
246 }
247 if (filp->f_flags & O_NONBLOCK) {
248 /* Indicate we are open */
249 if (tty->termios->c_cflag & CBAUD)
250 tty_port_raise_dtr_rts(port);
251 port->flags |= ASYNC_NORMAL_ACTIVE;
252 return 0;
253 }
254
255 if (C_CLOCAL(tty))
256 do_clocal = 1;
257
258 /* Block waiting until we can proceed. We may need to wait for the
259 carrier, but we must also wait for any close that is in progress
260 before the next open may complete */
261
262 retval = 0;
263
264 /* The port lock protects the port counts */
265 spin_lock_irqsave(&port->lock, flags);
266 if (!tty_hung_up_p(filp))
267 port->count--;
268 port->blocked_open++;
269 spin_unlock_irqrestore(&port->lock, flags);
270
271 while (1) {
272 /* Indicate we are open */
273 if (tty->termios->c_cflag & CBAUD)
274 tty_port_raise_dtr_rts(port);
275
276 prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
277 /* Check for a hangup or uninitialised port.
278 Return accordingly */
279 if (tty_hung_up_p(filp) || !(port->flags & ASYNC_INITIALIZED)) {
280 if (port->flags & ASYNC_HUP_NOTIFY)
281 retval = -EAGAIN;
282 else
283 retval = -ERESTARTSYS;
284 break;
285 }
286 /*
287 * Probe the carrier. For devices with no carrier detect
288 * tty_port_carrier_raised will always return true.
289 * Never ask drivers if CLOCAL is set, this causes troubles
290 * on some hardware.
291 */
292 if (!(port->flags & ASYNC_CLOSING) &&
293 (do_clocal || tty_port_carrier_raised(port)))
294 break;
295 if (signal_pending(current)) {
296 retval = -ERESTARTSYS;
297 break;
298 }
299 tty_unlock();
300 schedule();
301 tty_lock();
302 }
303 finish_wait(&port->open_wait, &wait);
304
305 /* Update counts. A parallel hangup will have set count to zero and
306 we must not mess that up further */
307 spin_lock_irqsave(&port->lock, flags);
308 if (!tty_hung_up_p(filp))
309 port->count++;
310 port->blocked_open--;
311 if (retval == 0)
312 port->flags |= ASYNC_NORMAL_ACTIVE;
313 spin_unlock_irqrestore(&port->lock, flags);
314 return retval;
315}
316EXPORT_SYMBOL(tty_port_block_til_ready);
317
318int tty_port_close_start(struct tty_port *port,
319 struct tty_struct *tty, struct file *filp)
320{
321 unsigned long flags;
322
323 spin_lock_irqsave(&port->lock, flags);
324 if (tty_hung_up_p(filp)) {
325 spin_unlock_irqrestore(&port->lock, flags);
326 return 0;
327 }
328
329 if (tty->count == 1 && port->count != 1) {
330 printk(KERN_WARNING
331 "tty_port_close_start: tty->count = 1 port count = %d.\n",
332 port->count);
333 port->count = 1;
334 }
335 if (--port->count < 0) {
336 printk(KERN_WARNING "tty_port_close_start: count = %d\n",
337 port->count);
338 port->count = 0;
339 }
340
341 if (port->count) {
342 spin_unlock_irqrestore(&port->lock, flags);
343 if (port->ops->drop)
344 port->ops->drop(port);
345 return 0;
346 }
347 set_bit(ASYNCB_CLOSING, &port->flags);
348 tty->closing = 1;
349 spin_unlock_irqrestore(&port->lock, flags);
350 /* Don't block on a stalled port, just pull the chain */
351 if (tty->flow_stopped)
352 tty_driver_flush_buffer(tty);
353 if (test_bit(ASYNCB_INITIALIZED, &port->flags) &&
354 port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
355 tty_wait_until_sent_from_close(tty, port->closing_wait);
356 if (port->drain_delay) {
357 unsigned int bps = tty_get_baud_rate(tty);
358 long timeout;
359
360 if (bps > 1200)
361 timeout = max_t(long,
362 (HZ * 10 * port->drain_delay) / bps, HZ / 10);
363 else
364 timeout = 2 * HZ;
365 schedule_timeout_interruptible(timeout);
366 }
367 /* Flush the ldisc buffering */
368 tty_ldisc_flush(tty);
369
370 /* Drop DTR/RTS if HUPCL is set. This causes any attached modem to
371 hang up the line */
372 if (tty->termios->c_cflag & HUPCL)
373 tty_port_lower_dtr_rts(port);
374
375 /* Don't call port->drop for the last reference. Callers will want
376 to drop the last active reference in ->shutdown() or the tty
377 shutdown path */
378 return 1;
379}
380EXPORT_SYMBOL(tty_port_close_start);
381
382void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
383{
384 unsigned long flags;
385
386 spin_lock_irqsave(&port->lock, flags);
387 tty->closing = 0;
388
389 if (port->blocked_open) {
390 spin_unlock_irqrestore(&port->lock, flags);
391 if (port->close_delay) {
392 msleep_interruptible(
393 jiffies_to_msecs(port->close_delay));
394 }
395 spin_lock_irqsave(&port->lock, flags);
396 wake_up_interruptible(&port->open_wait);
397 }
398 port->flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_CLOSING);
399 wake_up_interruptible(&port->close_wait);
400 spin_unlock_irqrestore(&port->lock, flags);
401}
402EXPORT_SYMBOL(tty_port_close_end);
403
404void tty_port_close(struct tty_port *port, struct tty_struct *tty,
405 struct file *filp)
406{
407 if (tty_port_close_start(port, tty, filp) == 0)
408 return;
409 tty_port_shutdown(port);
410 set_bit(TTY_IO_ERROR, &tty->flags);
411 tty_port_close_end(port, tty);
412 tty_port_tty_set(port, NULL);
413}
414EXPORT_SYMBOL(tty_port_close);
415
416int tty_port_open(struct tty_port *port, struct tty_struct *tty,
417 struct file *filp)
418{
419 spin_lock_irq(&port->lock);
420 if (!tty_hung_up_p(filp))
421 ++port->count;
422 spin_unlock_irq(&port->lock);
423 tty_port_tty_set(port, tty);
424
425 /*
426 * Do the device-specific open only if the hardware isn't
427 * already initialized. Serialize open and shutdown using the
428 * port mutex.
429 */
430
431 mutex_lock(&port->mutex);
432
433 if (!test_bit(ASYNCB_INITIALIZED, &port->flags)) {
434 clear_bit(TTY_IO_ERROR, &tty->flags);
435 if (port->ops->activate) {
436 int retval = port->ops->activate(port, tty);
437 if (retval) {
438 mutex_unlock(&port->mutex);
439 return retval;
440 }
441 }
442 set_bit(ASYNCB_INITIALIZED, &port->flags);
443 }
444 mutex_unlock(&port->mutex);
445 return tty_port_block_til_ready(port, tty, filp);
446}
447
448EXPORT_SYMBOL(tty_port_open);