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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/*
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 (tty_port_initialized(port)) {
208 tty_port_set_initialized(port, 0);
209 /*
210 * Drop DTR/RTS if HUPCL is set. This causes any attached
211 * modem to hang up the line.
212 */
213 if (tty && C_HUPCL(tty))
214 tty_port_lower_dtr_rts(port);
215
216 if (port->ops->shutdown)
217 port->ops->shutdown(port);
218 }
219out:
220 mutex_unlock(&port->mutex);
221}
222
223/**
224 * tty_port_hangup - hangup helper
225 * @port: tty port
226 *
227 * Perform port level tty hangup flag and count changes. Drop the tty
228 * reference.
229 *
230 * Caller holds tty lock.
231 */
232
233void tty_port_hangup(struct tty_port *port)
234{
235 struct tty_struct *tty;
236 unsigned long flags;
237
238 spin_lock_irqsave(&port->lock, flags);
239 port->count = 0;
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_set_active(port, 0);
246 tty_port_shutdown(port, tty);
247 tty_kref_put(tty);
248 wake_up_interruptible(&port->open_wait);
249 wake_up_interruptible(&port->delta_msr_wait);
250}
251EXPORT_SYMBOL(tty_port_hangup);
252
253/**
254 * tty_port_tty_hangup - helper to hang up a tty
255 *
256 * @port: tty port
257 * @check_clocal: hang only ttys with CLOCAL unset?
258 */
259void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
260{
261 struct tty_struct *tty = tty_port_tty_get(port);
262
263 if (tty && (!check_clocal || !C_CLOCAL(tty)))
264 tty_hangup(tty);
265 tty_kref_put(tty);
266}
267EXPORT_SYMBOL_GPL(tty_port_tty_hangup);
268
269/**
270 * tty_port_tty_wakeup - helper to wake up a tty
271 *
272 * @port: tty port
273 */
274void tty_port_tty_wakeup(struct tty_port *port)
275{
276 struct tty_struct *tty = tty_port_tty_get(port);
277
278 if (tty) {
279 tty_wakeup(tty);
280 tty_kref_put(tty);
281 }
282}
283EXPORT_SYMBOL_GPL(tty_port_tty_wakeup);
284
285/**
286 * tty_port_carrier_raised - carrier raised check
287 * @port: tty port
288 *
289 * Wrapper for the carrier detect logic. For the moment this is used
290 * to hide some internal details. This will eventually become entirely
291 * internal to the tty port.
292 */
293
294int tty_port_carrier_raised(struct tty_port *port)
295{
296 if (port->ops->carrier_raised == NULL)
297 return 1;
298 return port->ops->carrier_raised(port);
299}
300EXPORT_SYMBOL(tty_port_carrier_raised);
301
302/**
303 * tty_port_raise_dtr_rts - Raise DTR/RTS
304 * @port: tty port
305 *
306 * Wrapper for the DTR/RTS raise logic. For the moment this is used
307 * to hide some internal details. This will eventually become entirely
308 * internal to the tty port.
309 */
310
311void tty_port_raise_dtr_rts(struct tty_port *port)
312{
313 if (port->ops->dtr_rts)
314 port->ops->dtr_rts(port, 1);
315}
316EXPORT_SYMBOL(tty_port_raise_dtr_rts);
317
318/**
319 * tty_port_lower_dtr_rts - Lower DTR/RTS
320 * @port: tty port
321 *
322 * Wrapper for the DTR/RTS raise logic. For the moment this is used
323 * to hide some internal details. This will eventually become entirely
324 * internal to the tty port.
325 */
326
327void tty_port_lower_dtr_rts(struct tty_port *port)
328{
329 if (port->ops->dtr_rts)
330 port->ops->dtr_rts(port, 0);
331}
332EXPORT_SYMBOL(tty_port_lower_dtr_rts);
333
334/**
335 * tty_port_block_til_ready - Waiting logic for tty open
336 * @port: the tty port being opened
337 * @tty: the tty device being bound
338 * @filp: the file pointer of the opener
339 *
340 * Implement the core POSIX/SuS tty behaviour when opening a tty device.
341 * Handles:
342 * - hangup (both before and during)
343 * - non blocking open
344 * - rts/dtr/dcd
345 * - signals
346 * - port flags and counts
347 *
348 * The passed tty_port must implement the carrier_raised method if it can
349 * do carrier detect and the dtr_rts method if it supports software
350 * management of these lines. Note that the dtr/rts raise is done each
351 * iteration as a hangup may have previously dropped them while we wait.
352 *
353 * Caller holds tty lock.
354 *
355 * NB: May drop and reacquire tty lock when blocking, so tty and tty_port
356 * may have changed state (eg., may have been hung up).
357 */
358
359int tty_port_block_til_ready(struct tty_port *port,
360 struct tty_struct *tty, struct file *filp)
361{
362 int do_clocal = 0, retval;
363 unsigned long flags;
364 DEFINE_WAIT(wait);
365
366 /* if non-blocking mode is set we can pass directly to open unless
367 the port has just hung up or is in another error state */
368 if (tty_io_error(tty)) {
369 tty_port_set_active(port, 1);
370 return 0;
371 }
372 if (filp->f_flags & O_NONBLOCK) {
373 /* Indicate we are open */
374 if (C_BAUD(tty))
375 tty_port_raise_dtr_rts(port);
376 tty_port_set_active(port, 1);
377 return 0;
378 }
379
380 if (C_CLOCAL(tty))
381 do_clocal = 1;
382
383 /* Block waiting until we can proceed. We may need to wait for the
384 carrier, but we must also wait for any close that is in progress
385 before the next open may complete */
386
387 retval = 0;
388
389 /* The port lock protects the port counts */
390 spin_lock_irqsave(&port->lock, flags);
391 port->count--;
392 port->blocked_open++;
393 spin_unlock_irqrestore(&port->lock, flags);
394
395 while (1) {
396 /* Indicate we are open */
397 if (C_BAUD(tty) && tty_port_initialized(port))
398 tty_port_raise_dtr_rts(port);
399
400 prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE);
401 /* Check for a hangup or uninitialised port.
402 Return accordingly */
403 if (tty_hung_up_p(filp) || !tty_port_initialized(port)) {
404 if (port->flags & ASYNC_HUP_NOTIFY)
405 retval = -EAGAIN;
406 else
407 retval = -ERESTARTSYS;
408 break;
409 }
410 /*
411 * Probe the carrier. For devices with no carrier detect
412 * tty_port_carrier_raised will always return true.
413 * Never ask drivers if CLOCAL is set, this causes troubles
414 * on some hardware.
415 */
416 if (do_clocal || tty_port_carrier_raised(port))
417 break;
418 if (signal_pending(current)) {
419 retval = -ERESTARTSYS;
420 break;
421 }
422 tty_unlock(tty);
423 schedule();
424 tty_lock(tty);
425 }
426 finish_wait(&port->open_wait, &wait);
427
428 /* Update counts. A parallel hangup will have set count to zero and
429 we must not mess that up further */
430 spin_lock_irqsave(&port->lock, flags);
431 if (!tty_hung_up_p(filp))
432 port->count++;
433 port->blocked_open--;
434 spin_unlock_irqrestore(&port->lock, flags);
435 if (retval == 0)
436 tty_port_set_active(port, 1);
437 return retval;
438}
439EXPORT_SYMBOL(tty_port_block_til_ready);
440
441static void tty_port_drain_delay(struct tty_port *port, struct tty_struct *tty)
442{
443 unsigned int bps = tty_get_baud_rate(tty);
444 long timeout;
445
446 if (bps > 1200) {
447 timeout = (HZ * 10 * port->drain_delay) / bps;
448 timeout = max_t(long, timeout, HZ / 10);
449 } else {
450 timeout = 2 * HZ;
451 }
452 schedule_timeout_interruptible(timeout);
453}
454
455/* Caller holds tty lock. */
456int tty_port_close_start(struct tty_port *port,
457 struct tty_struct *tty, struct file *filp)
458{
459 unsigned long flags;
460
461 if (tty_hung_up_p(filp))
462 return 0;
463
464 spin_lock_irqsave(&port->lock, flags);
465 if (tty->count == 1 && port->count != 1) {
466 tty_warn(tty, "%s: tty->count = 1 port count = %d\n", __func__,
467 port->count);
468 port->count = 1;
469 }
470 if (--port->count < 0) {
471 tty_warn(tty, "%s: bad port count (%d)\n", __func__,
472 port->count);
473 port->count = 0;
474 }
475
476 if (port->count) {
477 spin_unlock_irqrestore(&port->lock, flags);
478 return 0;
479 }
480 spin_unlock_irqrestore(&port->lock, flags);
481
482 tty->closing = 1;
483
484 if (tty_port_initialized(port)) {
485 /* Don't block on a stalled port, just pull the chain */
486 if (tty->flow_stopped)
487 tty_driver_flush_buffer(tty);
488 if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
489 tty_wait_until_sent(tty, port->closing_wait);
490 if (port->drain_delay)
491 tty_port_drain_delay(port, tty);
492 }
493 /* Flush the ldisc buffering */
494 tty_ldisc_flush(tty);
495
496 /* Report to caller this is the last port reference */
497 return 1;
498}
499EXPORT_SYMBOL(tty_port_close_start);
500
501/* Caller holds tty lock */
502void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
503{
504 unsigned long flags;
505
506 tty_ldisc_flush(tty);
507 tty->closing = 0;
508
509 spin_lock_irqsave(&port->lock, flags);
510
511 if (port->blocked_open) {
512 spin_unlock_irqrestore(&port->lock, flags);
513 if (port->close_delay)
514 msleep_interruptible(jiffies_to_msecs(port->close_delay));
515 spin_lock_irqsave(&port->lock, flags);
516 wake_up_interruptible(&port->open_wait);
517 }
518 spin_unlock_irqrestore(&port->lock, flags);
519 tty_port_set_active(port, 0);
520}
521EXPORT_SYMBOL(tty_port_close_end);
522
523/**
524 * tty_port_close
525 *
526 * Caller holds tty lock
527 */
528void tty_port_close(struct tty_port *port, struct tty_struct *tty,
529 struct file *filp)
530{
531 if (tty_port_close_start(port, tty, filp) == 0)
532 return;
533 tty_port_shutdown(port, tty);
534 set_bit(TTY_IO_ERROR, &tty->flags);
535 tty_port_close_end(port, tty);
536 tty_port_tty_set(port, NULL);
537}
538EXPORT_SYMBOL(tty_port_close);
539
540/**
541 * tty_port_install - generic tty->ops->install handler
542 * @port: tty_port of the device
543 * @driver: tty_driver for this device
544 * @tty: tty to be installed
545 *
546 * It is the same as tty_standard_install except the provided @port is linked
547 * to a concrete tty specified by @tty. Use this or tty_port_register_device
548 * (or both). Call tty_port_link_device as a last resort.
549 */
550int tty_port_install(struct tty_port *port, struct tty_driver *driver,
551 struct tty_struct *tty)
552{
553 tty->port = port;
554 return tty_standard_install(driver, tty);
555}
556EXPORT_SYMBOL_GPL(tty_port_install);
557
558/**
559 * tty_port_open
560 *
561 * Caller holds tty lock.
562 *
563 * NB: may drop and reacquire tty lock (in tty_port_block_til_ready()) so
564 * tty and tty_port may have changed state (eg., may be hung up now)
565 */
566int tty_port_open(struct tty_port *port, struct tty_struct *tty,
567 struct file *filp)
568{
569 spin_lock_irq(&port->lock);
570 ++port->count;
571 spin_unlock_irq(&port->lock);
572 tty_port_tty_set(port, tty);
573
574 /*
575 * Do the device-specific open only if the hardware isn't
576 * already initialized. Serialize open and shutdown using the
577 * port mutex.
578 */
579
580 mutex_lock(&port->mutex);
581
582 if (!tty_port_initialized(port)) {
583 clear_bit(TTY_IO_ERROR, &tty->flags);
584 if (port->ops->activate) {
585 int retval = port->ops->activate(port, tty);
586 if (retval) {
587 mutex_unlock(&port->mutex);
588 return retval;
589 }
590 }
591 tty_port_set_initialized(port, 1);
592 }
593 mutex_unlock(&port->mutex);
594 return tty_port_block_til_ready(port, tty, filp);
595}
596
597EXPORT_SYMBOL(tty_port_open);