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