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