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Commit | Line | Data |
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9e48565d AC |
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> | |
3e61696b | 10 | #include <linux/serial.h> |
9e48565d AC |
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 | ||
21 | void 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 | mutex_init(&port->mutex); | |
4a90f09b | 27 | spin_lock_init(&port->lock); |
9e48565d AC |
28 | port->close_delay = (50 * HZ) / 100; |
29 | port->closing_wait = (3000 * HZ) / 100; | |
30 | } | |
31 | EXPORT_SYMBOL(tty_port_init); | |
32 | ||
33 | int tty_port_alloc_xmit_buf(struct tty_port *port) | |
34 | { | |
35 | /* We may sleep in get_zeroed_page() */ | |
36 | mutex_lock(&port->mutex); | |
37 | if (port->xmit_buf == NULL) | |
38 | port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL); | |
39 | mutex_unlock(&port->mutex); | |
40 | if (port->xmit_buf == NULL) | |
41 | return -ENOMEM; | |
42 | return 0; | |
43 | } | |
44 | EXPORT_SYMBOL(tty_port_alloc_xmit_buf); | |
45 | ||
46 | void tty_port_free_xmit_buf(struct tty_port *port) | |
47 | { | |
48 | mutex_lock(&port->mutex); | |
49 | if (port->xmit_buf != NULL) { | |
50 | free_page((unsigned long)port->xmit_buf); | |
51 | port->xmit_buf = NULL; | |
52 | } | |
53 | mutex_unlock(&port->mutex); | |
54 | } | |
55 | EXPORT_SYMBOL(tty_port_free_xmit_buf); | |
56 | ||
57 | ||
4a90f09b AC |
58 | /** |
59 | * tty_port_tty_get - get a tty reference | |
60 | * @port: tty port | |
61 | * | |
62 | * Return a refcount protected tty instance or NULL if the port is not | |
63 | * associated with a tty (eg due to close or hangup) | |
64 | */ | |
65 | ||
66 | struct tty_struct *tty_port_tty_get(struct tty_port *port) | |
67 | { | |
68 | unsigned long flags; | |
69 | struct tty_struct *tty; | |
70 | ||
71 | spin_lock_irqsave(&port->lock, flags); | |
72 | tty = tty_kref_get(port->tty); | |
73 | spin_unlock_irqrestore(&port->lock, flags); | |
74 | return tty; | |
75 | } | |
76 | EXPORT_SYMBOL(tty_port_tty_get); | |
77 | ||
78 | /** | |
79 | * tty_port_tty_set - set the tty of a port | |
80 | * @port: tty port | |
81 | * @tty: the tty | |
82 | * | |
83 | * Associate the port and tty pair. Manages any internal refcounts. | |
84 | * Pass NULL to deassociate a port | |
85 | */ | |
86 | ||
87 | void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty) | |
88 | { | |
89 | unsigned long flags; | |
90 | ||
91 | spin_lock_irqsave(&port->lock, flags); | |
92 | if (port->tty) | |
93 | tty_kref_put(port->tty); | |
cb4bca35 | 94 | port->tty = tty_kref_get(tty); |
4a90f09b AC |
95 | spin_unlock_irqrestore(&port->lock, flags); |
96 | } | |
97 | EXPORT_SYMBOL(tty_port_tty_set); | |
31f35939 | 98 | |
7ca0ff9a AC |
99 | static void tty_port_shutdown(struct tty_port *port) |
100 | { | |
101 | if (port->ops->shutdown && | |
102 | test_and_clear_bit(ASYNC_INITIALIZED, &port->flags)) | |
103 | port->ops->shutdown(port); | |
104 | ||
105 | } | |
106 | ||
3e61696b AC |
107 | /** |
108 | * tty_port_hangup - hangup helper | |
109 | * @port: tty port | |
110 | * | |
111 | * Perform port level tty hangup flag and count changes. Drop the tty | |
112 | * reference. | |
113 | */ | |
114 | ||
115 | void tty_port_hangup(struct tty_port *port) | |
116 | { | |
117 | unsigned long flags; | |
118 | ||
119 | spin_lock_irqsave(&port->lock, flags); | |
120 | port->count = 0; | |
121 | port->flags &= ~ASYNC_NORMAL_ACTIVE; | |
122 | if (port->tty) | |
123 | tty_kref_put(port->tty); | |
124 | port->tty = NULL; | |
125 | spin_unlock_irqrestore(&port->lock, flags); | |
126 | wake_up_interruptible(&port->open_wait); | |
7ca0ff9a | 127 | tty_port_shutdown(port); |
3e61696b AC |
128 | } |
129 | EXPORT_SYMBOL(tty_port_hangup); | |
130 | ||
31f35939 AC |
131 | /** |
132 | * tty_port_carrier_raised - carrier raised check | |
133 | * @port: tty port | |
134 | * | |
135 | * Wrapper for the carrier detect logic. For the moment this is used | |
136 | * to hide some internal details. This will eventually become entirely | |
137 | * internal to the tty port. | |
138 | */ | |
139 | ||
140 | int tty_port_carrier_raised(struct tty_port *port) | |
141 | { | |
142 | if (port->ops->carrier_raised == NULL) | |
143 | return 1; | |
144 | return port->ops->carrier_raised(port); | |
145 | } | |
146 | EXPORT_SYMBOL(tty_port_carrier_raised); | |
5d951fb4 AC |
147 | |
148 | /** | |
fcc8ac18 | 149 | * tty_port_raise_dtr_rts - Raise DTR/RTS |
5d951fb4 AC |
150 | * @port: tty port |
151 | * | |
152 | * Wrapper for the DTR/RTS raise logic. For the moment this is used | |
153 | * to hide some internal details. This will eventually become entirely | |
154 | * internal to the tty port. | |
155 | */ | |
156 | ||
157 | void tty_port_raise_dtr_rts(struct tty_port *port) | |
158 | { | |
fcc8ac18 AC |
159 | if (port->ops->dtr_rts) |
160 | port->ops->dtr_rts(port, 1); | |
5d951fb4 AC |
161 | } |
162 | EXPORT_SYMBOL(tty_port_raise_dtr_rts); | |
36c621d8 | 163 | |
fcc8ac18 AC |
164 | /** |
165 | * tty_port_lower_dtr_rts - Lower DTR/RTS | |
166 | * @port: tty port | |
167 | * | |
168 | * Wrapper for the DTR/RTS raise logic. For the moment this is used | |
169 | * to hide some internal details. This will eventually become entirely | |
170 | * internal to the tty port. | |
171 | */ | |
172 | ||
173 | void tty_port_lower_dtr_rts(struct tty_port *port) | |
174 | { | |
175 | if (port->ops->dtr_rts) | |
176 | port->ops->dtr_rts(port, 0); | |
177 | } | |
178 | EXPORT_SYMBOL(tty_port_lower_dtr_rts); | |
179 | ||
36c621d8 AC |
180 | /** |
181 | * tty_port_block_til_ready - Waiting logic for tty open | |
182 | * @port: the tty port being opened | |
183 | * @tty: the tty device being bound | |
184 | * @filp: the file pointer of the opener | |
185 | * | |
186 | * Implement the core POSIX/SuS tty behaviour when opening a tty device. | |
187 | * Handles: | |
188 | * - hangup (both before and during) | |
189 | * - non blocking open | |
190 | * - rts/dtr/dcd | |
191 | * - signals | |
192 | * - port flags and counts | |
193 | * | |
194 | * The passed tty_port must implement the carrier_raised method if it can | |
fcc8ac18 | 195 | * do carrier detect and the dtr_rts method if it supports software |
36c621d8 AC |
196 | * management of these lines. Note that the dtr/rts raise is done each |
197 | * iteration as a hangup may have previously dropped them while we wait. | |
198 | */ | |
199 | ||
200 | int tty_port_block_til_ready(struct tty_port *port, | |
201 | struct tty_struct *tty, struct file *filp) | |
202 | { | |
203 | int do_clocal = 0, retval; | |
204 | unsigned long flags; | |
6af9a43d | 205 | DEFINE_WAIT(wait); |
36c621d8 AC |
206 | int cd; |
207 | ||
208 | /* block if port is in the process of being closed */ | |
209 | if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) { | |
5fc5b42a JS |
210 | wait_event_interruptible(port->close_wait, |
211 | !(port->flags & ASYNC_CLOSING)); | |
36c621d8 AC |
212 | if (port->flags & ASYNC_HUP_NOTIFY) |
213 | return -EAGAIN; | |
214 | else | |
215 | return -ERESTARTSYS; | |
216 | } | |
217 | ||
218 | /* if non-blocking mode is set we can pass directly to open unless | |
219 | the port has just hung up or is in another error state */ | |
220 | if ((filp->f_flags & O_NONBLOCK) || | |
221 | (tty->flags & (1 << TTY_IO_ERROR))) { | |
222 | port->flags |= ASYNC_NORMAL_ACTIVE; | |
223 | return 0; | |
224 | } | |
225 | ||
226 | if (C_CLOCAL(tty)) | |
227 | do_clocal = 1; | |
228 | ||
229 | /* Block waiting until we can proceed. We may need to wait for the | |
230 | carrier, but we must also wait for any close that is in progress | |
231 | before the next open may complete */ | |
232 | ||
233 | retval = 0; | |
36c621d8 AC |
234 | |
235 | /* The port lock protects the port counts */ | |
236 | spin_lock_irqsave(&port->lock, flags); | |
237 | if (!tty_hung_up_p(filp)) | |
238 | port->count--; | |
239 | port->blocked_open++; | |
240 | spin_unlock_irqrestore(&port->lock, flags); | |
241 | ||
242 | while (1) { | |
243 | /* Indicate we are open */ | |
7834909f AC |
244 | if (tty->termios->c_cflag & CBAUD) |
245 | tty_port_raise_dtr_rts(port); | |
36c621d8 | 246 | |
3e3b5c08 | 247 | prepare_to_wait(&port->open_wait, &wait, TASK_INTERRUPTIBLE); |
36c621d8 AC |
248 | /* Check for a hangup or uninitialised port. Return accordingly */ |
249 | if (tty_hung_up_p(filp) || !(port->flags & ASYNC_INITIALIZED)) { | |
250 | if (port->flags & ASYNC_HUP_NOTIFY) | |
251 | retval = -EAGAIN; | |
252 | else | |
253 | retval = -ERESTARTSYS; | |
254 | break; | |
255 | } | |
256 | /* Probe the carrier. For devices with no carrier detect this | |
257 | will always return true */ | |
258 | cd = tty_port_carrier_raised(port); | |
259 | if (!(port->flags & ASYNC_CLOSING) && | |
260 | (do_clocal || cd)) | |
261 | break; | |
262 | if (signal_pending(current)) { | |
263 | retval = -ERESTARTSYS; | |
264 | break; | |
265 | } | |
266 | schedule(); | |
267 | } | |
3e3b5c08 | 268 | finish_wait(&port->open_wait, &wait); |
36c621d8 AC |
269 | |
270 | /* Update counts. A parallel hangup will have set count to zero and | |
271 | we must not mess that up further */ | |
272 | spin_lock_irqsave(&port->lock, flags); | |
273 | if (!tty_hung_up_p(filp)) | |
274 | port->count++; | |
275 | port->blocked_open--; | |
276 | if (retval == 0) | |
277 | port->flags |= ASYNC_NORMAL_ACTIVE; | |
278 | spin_unlock_irqrestore(&port->lock, flags); | |
ecc2e05e | 279 | return retval; |
36c621d8 AC |
280 | |
281 | } | |
282 | EXPORT_SYMBOL(tty_port_block_til_ready); | |
283 | ||
a6614999 AC |
284 | int tty_port_close_start(struct tty_port *port, struct tty_struct *tty, struct file *filp) |
285 | { | |
286 | unsigned long flags; | |
287 | ||
288 | spin_lock_irqsave(&port->lock, flags); | |
289 | if (tty_hung_up_p(filp)) { | |
290 | spin_unlock_irqrestore(&port->lock, flags); | |
291 | return 0; | |
292 | } | |
293 | ||
294 | if( tty->count == 1 && port->count != 1) { | |
295 | printk(KERN_WARNING | |
296 | "tty_port_close_start: tty->count = 1 port count = %d.\n", | |
297 | port->count); | |
298 | port->count = 1; | |
299 | } | |
300 | if (--port->count < 0) { | |
301 | printk(KERN_WARNING "tty_port_close_start: count = %d\n", | |
302 | port->count); | |
303 | port->count = 0; | |
304 | } | |
305 | ||
306 | if (port->count) { | |
307 | spin_unlock_irqrestore(&port->lock, flags); | |
7ca0ff9a AC |
308 | if (port->ops->drop) |
309 | port->ops->drop(port); | |
a6614999 AC |
310 | return 0; |
311 | } | |
7ca0ff9a | 312 | set_bit(ASYNC_CLOSING, &port->flags); |
a6614999 AC |
313 | tty->closing = 1; |
314 | spin_unlock_irqrestore(&port->lock, flags); | |
fba85e01 AC |
315 | /* Don't block on a stalled port, just pull the chain */ |
316 | if (tty->flow_stopped) | |
317 | tty_driver_flush_buffer(tty); | |
7ca0ff9a | 318 | if (test_bit(ASYNCB_INITIALIZED, &port->flags) && |
6ed1dbae | 319 | port->closing_wait != ASYNC_CLOSING_WAIT_NONE) |
a6614999 | 320 | tty_wait_until_sent(tty, port->closing_wait); |
1ec739be AC |
321 | if (port->drain_delay) { |
322 | unsigned int bps = tty_get_baud_rate(tty); | |
323 | long timeout; | |
324 | ||
325 | if (bps > 1200) | |
326 | timeout = max_t(long, (HZ * 10 * port->drain_delay) / bps, | |
327 | HZ / 10); | |
328 | else | |
329 | timeout = 2 * HZ; | |
330 | schedule_timeout_interruptible(timeout); | |
331 | } | |
7ca0ff9a AC |
332 | /* Don't call port->drop for the last reference. Callers will want |
333 | to drop the last active reference in ->shutdown() or the tty | |
334 | shutdown path */ | |
a6614999 AC |
335 | return 1; |
336 | } | |
337 | EXPORT_SYMBOL(tty_port_close_start); | |
338 | ||
339 | void tty_port_close_end(struct tty_port *port, struct tty_struct *tty) | |
340 | { | |
341 | unsigned long flags; | |
342 | ||
343 | tty_ldisc_flush(tty); | |
344 | ||
fcc8ac18 AC |
345 | if (tty->termios->c_cflag & HUPCL) |
346 | tty_port_lower_dtr_rts(port); | |
347 | ||
a6614999 AC |
348 | spin_lock_irqsave(&port->lock, flags); |
349 | tty->closing = 0; | |
350 | ||
351 | if (port->blocked_open) { | |
352 | spin_unlock_irqrestore(&port->lock, flags); | |
353 | if (port->close_delay) { | |
354 | msleep_interruptible( | |
355 | jiffies_to_msecs(port->close_delay)); | |
356 | } | |
357 | spin_lock_irqsave(&port->lock, flags); | |
358 | wake_up_interruptible(&port->open_wait); | |
359 | } | |
360 | port->flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_CLOSING); | |
361 | wake_up_interruptible(&port->close_wait); | |
362 | spin_unlock_irqrestore(&port->lock, flags); | |
363 | } | |
364 | EXPORT_SYMBOL(tty_port_close_end); | |
7ca0ff9a AC |
365 | |
366 | void tty_port_close(struct tty_port *port, struct tty_struct *tty, | |
367 | struct file *filp) | |
368 | { | |
369 | if (tty_port_close_start(port, tty, filp) == 0) | |
370 | return; | |
371 | tty_port_shutdown(port); | |
372 | tty_port_close_end(port, tty); | |
373 | tty_port_tty_set(port, NULL); | |
374 | } | |
375 | EXPORT_SYMBOL(tty_port_close); |