Loading...
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);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Tty port functions
4 */
5
6#include <linux/types.h>
7#include <linux/errno.h>
8#include <linux/tty.h>
9#include <linux/tty_driver.h>
10#include <linux/tty_flip.h>
11#include <linux/serial.h>
12#include <linux/timer.h>
13#include <linux/string.h>
14#include <linux/slab.h>
15#include <linux/sched/signal.h>
16#include <linux/wait.h>
17#include <linux/bitops.h>
18#include <linux/delay.h>
19#include <linux/module.h>
20#include <linux/serdev.h>
21
22static int tty_port_default_receive_buf(struct tty_port *port,
23 const unsigned char *p,
24 const unsigned char *f, size_t count)
25{
26 int ret;
27 struct tty_struct *tty;
28 struct tty_ldisc *disc;
29
30 tty = READ_ONCE(port->itty);
31 if (!tty)
32 return 0;
33
34 disc = tty_ldisc_ref(tty);
35 if (!disc)
36 return 0;
37
38 ret = tty_ldisc_receive_buf(disc, p, (char *)f, count);
39
40 tty_ldisc_deref(disc);
41
42 return ret;
43}
44
45static void tty_port_default_wakeup(struct tty_port *port)
46{
47 struct tty_struct *tty = tty_port_tty_get(port);
48
49 if (tty) {
50 tty_wakeup(tty);
51 tty_kref_put(tty);
52 }
53}
54
55static const struct tty_port_client_operations default_client_ops = {
56 .receive_buf = tty_port_default_receive_buf,
57 .write_wakeup = tty_port_default_wakeup,
58};
59
60void tty_port_init(struct tty_port *port)
61{
62 memset(port, 0, sizeof(*port));
63 tty_buffer_init(port);
64 init_waitqueue_head(&port->open_wait);
65 init_waitqueue_head(&port->delta_msr_wait);
66 mutex_init(&port->mutex);
67 mutex_init(&port->buf_mutex);
68 spin_lock_init(&port->lock);
69 port->close_delay = (50 * HZ) / 100;
70 port->closing_wait = (3000 * HZ) / 100;
71 port->client_ops = &default_client_ops;
72 kref_init(&port->kref);
73}
74EXPORT_SYMBOL(tty_port_init);
75
76/**
77 * tty_port_link_device - link tty and tty_port
78 * @port: tty_port of the device
79 * @driver: tty_driver for this device
80 * @index: index of the tty
81 *
82 * Provide the tty layer with a link from a tty (specified by @index) to a
83 * tty_port (@port). Use this only if neither tty_port_register_device nor
84 * tty_port_install is used in the driver. If used, this has to be called before
85 * tty_register_driver.
86 */
87void tty_port_link_device(struct tty_port *port,
88 struct tty_driver *driver, unsigned index)
89{
90 if (WARN_ON(index >= driver->num))
91 return;
92 driver->ports[index] = port;
93}
94EXPORT_SYMBOL_GPL(tty_port_link_device);
95
96/**
97 * tty_port_register_device - register tty device
98 * @port: tty_port of the device
99 * @driver: tty_driver for this device
100 * @index: index of the tty
101 * @device: parent if exists, otherwise NULL
102 *
103 * It is the same as tty_register_device except the provided @port is linked to
104 * a concrete tty specified by @index. Use this or tty_port_install (or both).
105 * Call tty_port_link_device as a last resort.
106 */
107struct device *tty_port_register_device(struct tty_port *port,
108 struct tty_driver *driver, unsigned index,
109 struct device *device)
110{
111 return tty_port_register_device_attr(port, driver, index, device, NULL, NULL);
112}
113EXPORT_SYMBOL_GPL(tty_port_register_device);
114
115/**
116 * tty_port_register_device_attr - register tty device
117 * @port: tty_port of the device
118 * @driver: tty_driver for this device
119 * @index: index of the tty
120 * @device: parent if exists, otherwise NULL
121 * @drvdata: Driver data to be set to device.
122 * @attr_grp: Attribute group to be set on device.
123 *
124 * It is the same as tty_register_device_attr except the provided @port is
125 * linked to a concrete tty specified by @index. Use this or tty_port_install
126 * (or both). Call tty_port_link_device as a last resort.
127 */
128struct device *tty_port_register_device_attr(struct tty_port *port,
129 struct tty_driver *driver, unsigned index,
130 struct device *device, void *drvdata,
131 const struct attribute_group **attr_grp)
132{
133 tty_port_link_device(port, driver, index);
134 return tty_register_device_attr(driver, index, device, drvdata,
135 attr_grp);
136}
137EXPORT_SYMBOL_GPL(tty_port_register_device_attr);
138
139/**
140 * tty_port_register_device_attr_serdev - register tty or serdev device
141 * @port: tty_port of the device
142 * @driver: tty_driver for this device
143 * @index: index of the tty
144 * @device: parent if exists, otherwise NULL
145 * @drvdata: driver data for the device
146 * @attr_grp: attribute group for the device
147 *
148 * Register a serdev or tty device depending on if the parent device has any
149 * defined serdev clients or not.
150 */
151struct device *tty_port_register_device_attr_serdev(struct tty_port *port,
152 struct tty_driver *driver, unsigned index,
153 struct device *device, void *drvdata,
154 const struct attribute_group **attr_grp)
155{
156 struct device *dev;
157
158 tty_port_link_device(port, driver, index);
159
160 dev = serdev_tty_port_register(port, device, driver, index);
161 if (PTR_ERR(dev) != -ENODEV) {
162 /* Skip creating cdev if we registered a serdev device */
163 return dev;
164 }
165
166 return tty_register_device_attr(driver, index, device, drvdata,
167 attr_grp);
168}
169EXPORT_SYMBOL_GPL(tty_port_register_device_attr_serdev);
170
171/**
172 * tty_port_register_device_serdev - register tty or serdev device
173 * @port: tty_port of the device
174 * @driver: tty_driver for this device
175 * @index: index of the tty
176 * @device: parent if exists, otherwise NULL
177 *
178 * Register a serdev or tty device depending on if the parent device has any
179 * defined serdev clients or not.
180 */
181struct device *tty_port_register_device_serdev(struct tty_port *port,
182 struct tty_driver *driver, unsigned index,
183 struct device *device)
184{
185 return tty_port_register_device_attr_serdev(port, driver, index,
186 device, NULL, NULL);
187}
188EXPORT_SYMBOL_GPL(tty_port_register_device_serdev);
189
190/**
191 * tty_port_unregister_device - deregister a tty or serdev device
192 * @port: tty_port of the device
193 * @driver: tty_driver for this device
194 * @index: index of the tty
195 *
196 * If a tty or serdev device is registered with a call to
197 * tty_port_register_device_serdev() then this function must be called when
198 * the device is gone.
199 */
200void tty_port_unregister_device(struct tty_port *port,
201 struct tty_driver *driver, unsigned index)
202{
203 int ret;
204
205 ret = serdev_tty_port_unregister(port);
206 if (ret == 0)
207 return;
208
209 tty_unregister_device(driver, index);
210}
211EXPORT_SYMBOL_GPL(tty_port_unregister_device);
212
213int tty_port_alloc_xmit_buf(struct tty_port *port)
214{
215 /* We may sleep in get_zeroed_page() */
216 mutex_lock(&port->buf_mutex);
217 if (port->xmit_buf == NULL)
218 port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
219 mutex_unlock(&port->buf_mutex);
220 if (port->xmit_buf == NULL)
221 return -ENOMEM;
222 return 0;
223}
224EXPORT_SYMBOL(tty_port_alloc_xmit_buf);
225
226void tty_port_free_xmit_buf(struct tty_port *port)
227{
228 mutex_lock(&port->buf_mutex);
229 if (port->xmit_buf != NULL) {
230 free_page((unsigned long)port->xmit_buf);
231 port->xmit_buf = NULL;
232 }
233 mutex_unlock(&port->buf_mutex);
234}
235EXPORT_SYMBOL(tty_port_free_xmit_buf);
236
237/**
238 * tty_port_destroy -- destroy inited port
239 * @port: tty port to be destroyed
240 *
241 * When a port was initialized using tty_port_init, one has to destroy the
242 * port by this function. Either indirectly by using tty_port refcounting
243 * (tty_port_put) or directly if refcounting is not used.
244 */
245void tty_port_destroy(struct tty_port *port)
246{
247 tty_buffer_cancel_work(port);
248 tty_buffer_free_all(port);
249}
250EXPORT_SYMBOL(tty_port_destroy);
251
252static void tty_port_destructor(struct kref *kref)
253{
254 struct tty_port *port = container_of(kref, struct tty_port, kref);
255
256 /* check if last port ref was dropped before tty release */
257 if (WARN_ON(port->itty))
258 return;
259 if (port->xmit_buf)
260 free_page((unsigned long)port->xmit_buf);
261 tty_port_destroy(port);
262 if (port->ops && port->ops->destruct)
263 port->ops->destruct(port);
264 else
265 kfree(port);
266}
267
268void tty_port_put(struct tty_port *port)
269{
270 if (port)
271 kref_put(&port->kref, tty_port_destructor);
272}
273EXPORT_SYMBOL(tty_port_put);
274
275/**
276 * tty_port_tty_get - get a tty reference
277 * @port: tty port
278 *
279 * Return a refcount protected tty instance or NULL if the port is not
280 * associated with a tty (eg due to close or hangup)
281 */
282
283struct tty_struct *tty_port_tty_get(struct tty_port *port)
284{
285 unsigned long flags;
286 struct tty_struct *tty;
287
288 spin_lock_irqsave(&port->lock, flags);
289 tty = tty_kref_get(port->tty);
290 spin_unlock_irqrestore(&port->lock, flags);
291 return tty;
292}
293EXPORT_SYMBOL(tty_port_tty_get);
294
295/**
296 * tty_port_tty_set - set the tty of a port
297 * @port: tty port
298 * @tty: the tty
299 *
300 * Associate the port and tty pair. Manages any internal refcounts.
301 * Pass NULL to deassociate a port
302 */
303
304void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
305{
306 unsigned long flags;
307
308 spin_lock_irqsave(&port->lock, flags);
309 tty_kref_put(port->tty);
310 port->tty = tty_kref_get(tty);
311 spin_unlock_irqrestore(&port->lock, flags);
312}
313EXPORT_SYMBOL(tty_port_tty_set);
314
315static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty)
316{
317 mutex_lock(&port->mutex);
318 if (port->console)
319 goto out;
320
321 if (tty_port_initialized(port)) {
322 tty_port_set_initialized(port, 0);
323 /*
324 * Drop DTR/RTS if HUPCL is set. This causes any attached
325 * modem to hang up the line.
326 */
327 if (tty && C_HUPCL(tty))
328 tty_port_lower_dtr_rts(port);
329
330 if (port->ops->shutdown)
331 port->ops->shutdown(port);
332 }
333out:
334 mutex_unlock(&port->mutex);
335}
336
337/**
338 * tty_port_hangup - hangup helper
339 * @port: tty port
340 *
341 * Perform port level tty hangup flag and count changes. Drop the tty
342 * reference.
343 *
344 * Caller holds tty lock.
345 */
346
347void tty_port_hangup(struct tty_port *port)
348{
349 struct tty_struct *tty;
350 unsigned long flags;
351
352 spin_lock_irqsave(&port->lock, flags);
353 port->count = 0;
354 tty = port->tty;
355 if (tty)
356 set_bit(TTY_IO_ERROR, &tty->flags);
357 port->tty = NULL;
358 spin_unlock_irqrestore(&port->lock, flags);
359 tty_port_set_active(port, 0);
360 tty_port_shutdown(port, tty);
361 tty_kref_put(tty);
362 wake_up_interruptible(&port->open_wait);
363 wake_up_interruptible(&port->delta_msr_wait);
364}
365EXPORT_SYMBOL(tty_port_hangup);
366
367/**
368 * tty_port_tty_hangup - helper to hang up a tty
369 *
370 * @port: tty port
371 * @check_clocal: hang only ttys with CLOCAL unset?
372 */
373void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
374{
375 struct tty_struct *tty = tty_port_tty_get(port);
376
377 if (tty && (!check_clocal || !C_CLOCAL(tty)))
378 tty_hangup(tty);
379 tty_kref_put(tty);
380}
381EXPORT_SYMBOL_GPL(tty_port_tty_hangup);
382
383/**
384 * tty_port_tty_wakeup - helper to wake up a tty
385 *
386 * @port: tty port
387 */
388void tty_port_tty_wakeup(struct tty_port *port)
389{
390 port->client_ops->write_wakeup(port);
391}
392EXPORT_SYMBOL_GPL(tty_port_tty_wakeup);
393
394/**
395 * tty_port_carrier_raised - carrier raised check
396 * @port: tty port
397 *
398 * Wrapper for the carrier detect logic. For the moment this is used
399 * to hide some internal details. This will eventually become entirely
400 * internal to the tty port.
401 */
402
403int tty_port_carrier_raised(struct tty_port *port)
404{
405 if (port->ops->carrier_raised == NULL)
406 return 1;
407 return port->ops->carrier_raised(port);
408}
409EXPORT_SYMBOL(tty_port_carrier_raised);
410
411/**
412 * tty_port_raise_dtr_rts - Raise DTR/RTS
413 * @port: tty port
414 *
415 * Wrapper for the DTR/RTS raise logic. For the moment this is used
416 * to hide some internal details. This will eventually become entirely
417 * internal to the tty port.
418 */
419
420void tty_port_raise_dtr_rts(struct tty_port *port)
421{
422 if (port->ops->dtr_rts)
423 port->ops->dtr_rts(port, 1);
424}
425EXPORT_SYMBOL(tty_port_raise_dtr_rts);
426
427/**
428 * tty_port_lower_dtr_rts - Lower DTR/RTS
429 * @port: tty port
430 *
431 * Wrapper for the DTR/RTS raise logic. For the moment this is used
432 * to hide some internal details. This will eventually become entirely
433 * internal to the tty port.
434 */
435
436void tty_port_lower_dtr_rts(struct tty_port *port)
437{
438 if (port->ops->dtr_rts)
439 port->ops->dtr_rts(port, 0);
440}
441EXPORT_SYMBOL(tty_port_lower_dtr_rts);
442
443/**
444 * tty_port_block_til_ready - Waiting logic for tty open
445 * @port: the tty port being opened
446 * @tty: the tty device being bound
447 * @filp: the file pointer of the opener or NULL
448 *
449 * Implement the core POSIX/SuS tty behaviour when opening a tty device.
450 * Handles:
451 * - hangup (both before and during)
452 * - non blocking open
453 * - rts/dtr/dcd
454 * - signals
455 * - port flags and counts
456 *
457 * The passed tty_port must implement the carrier_raised method if it can
458 * do carrier detect and the dtr_rts method if it supports software
459 * management of these lines. Note that the dtr/rts raise is done each
460 * iteration as a hangup may have previously dropped them while we wait.
461 *
462 * Caller holds tty lock.
463 *
464 * NB: May drop and reacquire tty lock when blocking, so tty and tty_port
465 * may have changed state (eg., may have been hung up).
466 */
467
468int tty_port_block_til_ready(struct tty_port *port,
469 struct tty_struct *tty, struct file *filp)
470{
471 int do_clocal = 0, retval;
472 unsigned long flags;
473 DEFINE_WAIT(wait);
474
475 /* if non-blocking mode is set we can pass directly to open unless
476 the port has just hung up or is in another error state */
477 if (tty_io_error(tty)) {
478 tty_port_set_active(port, 1);
479 return 0;
480 }
481 if (filp == NULL || (filp->f_flags & O_NONBLOCK)) {
482 /* Indicate we are open */
483 if (C_BAUD(tty))
484 tty_port_raise_dtr_rts(port);
485 tty_port_set_active(port, 1);
486 return 0;
487 }
488
489 if (C_CLOCAL(tty))
490 do_clocal = 1;
491
492 /* Block waiting until we can proceed. We may need to wait for the
493 carrier, but we must also wait for any close that is in progress
494 before the next open may complete */
495
496 retval = 0;
497
498 /* The port lock protects the port counts */
499 spin_lock_irqsave(&port->lock, flags);
500 port->count--;
501 port->blocked_open++;
502 spin_unlock_irqrestore(&port->lock, flags);
503
504 while (1) {
505 /* Indicate we are open */
506 if (C_BAUD(tty) && tty_port_initialized(port))
507 tty_port_raise_dtr_rts(port);
508
509 prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
510 /* Check for a hangup or uninitialised port.
511 Return accordingly */
512 if (tty_hung_up_p(filp) || !tty_port_initialized(port)) {
513 if (port->flags & ASYNC_HUP_NOTIFY)
514 retval = -EAGAIN;
515 else
516 retval = -ERESTARTSYS;
517 break;
518 }
519 /*
520 * Probe the carrier. For devices with no carrier detect
521 * tty_port_carrier_raised will always return true.
522 * Never ask drivers if CLOCAL is set, this causes troubles
523 * on some hardware.
524 */
525 if (do_clocal || tty_port_carrier_raised(port))
526 break;
527 if (signal_pending(current)) {
528 retval = -ERESTARTSYS;
529 break;
530 }
531 tty_unlock(tty);
532 schedule();
533 tty_lock(tty);
534 }
535 finish_wait(&port->open_wait, &wait);
536
537 /* Update counts. A parallel hangup will have set count to zero and
538 we must not mess that up further */
539 spin_lock_irqsave(&port->lock, flags);
540 if (!tty_hung_up_p(filp))
541 port->count++;
542 port->blocked_open--;
543 spin_unlock_irqrestore(&port->lock, flags);
544 if (retval == 0)
545 tty_port_set_active(port, 1);
546 return retval;
547}
548EXPORT_SYMBOL(tty_port_block_til_ready);
549
550static void tty_port_drain_delay(struct tty_port *port, struct tty_struct *tty)
551{
552 unsigned int bps = tty_get_baud_rate(tty);
553 long timeout;
554
555 if (bps > 1200) {
556 timeout = (HZ * 10 * port->drain_delay) / bps;
557 timeout = max_t(long, timeout, HZ / 10);
558 } else {
559 timeout = 2 * HZ;
560 }
561 schedule_timeout_interruptible(timeout);
562}
563
564/* Caller holds tty lock. */
565int tty_port_close_start(struct tty_port *port,
566 struct tty_struct *tty, struct file *filp)
567{
568 unsigned long flags;
569
570 if (tty_hung_up_p(filp))
571 return 0;
572
573 spin_lock_irqsave(&port->lock, flags);
574 if (tty->count == 1 && port->count != 1) {
575 tty_warn(tty, "%s: tty->count = 1 port count = %d\n", __func__,
576 port->count);
577 port->count = 1;
578 }
579 if (--port->count < 0) {
580 tty_warn(tty, "%s: bad port count (%d)\n", __func__,
581 port->count);
582 port->count = 0;
583 }
584
585 if (port->count) {
586 spin_unlock_irqrestore(&port->lock, flags);
587 return 0;
588 }
589 spin_unlock_irqrestore(&port->lock, flags);
590
591 tty->closing = 1;
592
593 if (tty_port_initialized(port)) {
594 /* Don't block on a stalled port, just pull the chain */
595 if (tty->flow_stopped)
596 tty_driver_flush_buffer(tty);
597 if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
598 tty_wait_until_sent(tty, port->closing_wait);
599 if (port->drain_delay)
600 tty_port_drain_delay(port, tty);
601 }
602 /* Flush the ldisc buffering */
603 tty_ldisc_flush(tty);
604
605 /* Report to caller this is the last port reference */
606 return 1;
607}
608EXPORT_SYMBOL(tty_port_close_start);
609
610/* Caller holds tty lock */
611void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
612{
613 unsigned long flags;
614
615 tty_ldisc_flush(tty);
616 tty->closing = 0;
617
618 spin_lock_irqsave(&port->lock, flags);
619
620 if (port->blocked_open) {
621 spin_unlock_irqrestore(&port->lock, flags);
622 if (port->close_delay)
623 msleep_interruptible(jiffies_to_msecs(port->close_delay));
624 spin_lock_irqsave(&port->lock, flags);
625 wake_up_interruptible(&port->open_wait);
626 }
627 spin_unlock_irqrestore(&port->lock, flags);
628 tty_port_set_active(port, 0);
629}
630EXPORT_SYMBOL(tty_port_close_end);
631
632/**
633 * tty_port_close
634 *
635 * Caller holds tty lock
636 */
637void tty_port_close(struct tty_port *port, struct tty_struct *tty,
638 struct file *filp)
639{
640 if (tty_port_close_start(port, tty, filp) == 0)
641 return;
642 tty_port_shutdown(port, tty);
643 set_bit(TTY_IO_ERROR, &tty->flags);
644 tty_port_close_end(port, tty);
645 tty_port_tty_set(port, NULL);
646}
647EXPORT_SYMBOL(tty_port_close);
648
649/**
650 * tty_port_install - generic tty->ops->install handler
651 * @port: tty_port of the device
652 * @driver: tty_driver for this device
653 * @tty: tty to be installed
654 *
655 * It is the same as tty_standard_install except the provided @port is linked
656 * to a concrete tty specified by @tty. Use this or tty_port_register_device
657 * (or both). Call tty_port_link_device as a last resort.
658 */
659int tty_port_install(struct tty_port *port, struct tty_driver *driver,
660 struct tty_struct *tty)
661{
662 tty->port = port;
663 return tty_standard_install(driver, tty);
664}
665EXPORT_SYMBOL_GPL(tty_port_install);
666
667/**
668 * tty_port_open
669 *
670 * Caller holds tty lock.
671 *
672 * NB: may drop and reacquire tty lock (in tty_port_block_til_ready()) so
673 * tty and tty_port may have changed state (eg., may be hung up now)
674 */
675int tty_port_open(struct tty_port *port, struct tty_struct *tty,
676 struct file *filp)
677{
678 spin_lock_irq(&port->lock);
679 ++port->count;
680 spin_unlock_irq(&port->lock);
681 tty_port_tty_set(port, tty);
682
683 /*
684 * Do the device-specific open only if the hardware isn't
685 * already initialized. Serialize open and shutdown using the
686 * port mutex.
687 */
688
689 mutex_lock(&port->mutex);
690
691 if (!tty_port_initialized(port)) {
692 clear_bit(TTY_IO_ERROR, &tty->flags);
693 if (port->ops->activate) {
694 int retval = port->ops->activate(port, tty);
695 if (retval) {
696 mutex_unlock(&port->mutex);
697 return retval;
698 }
699 }
700 tty_port_set_initialized(port, 1);
701 }
702 mutex_unlock(&port->mutex);
703 return tty_port_block_til_ready(port, tty, filp);
704}
705
706EXPORT_SYMBOL(tty_port_open);