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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
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);