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1 | /* generic HDLC line discipline for Linux |
2 | * |
3 | * Written by Paul Fulghum paulkf@microgate.com |
4 | * for Microgate Corporation |
5 | * |
6 | * Microgate and SyncLink are registered trademarks of Microgate Corporation |
7 | * |
8 | * Adapted from ppp.c, written by Michael Callahan <callahan@maths.ox.ac.uk>, |
9 | * Al Longyear <longyear@netcom.com>, |
10 | * Paul Mackerras <Paul.Mackerras@cs.anu.edu.au> |
11 | * |
12 | * Original release 01/11/99 |
13 | * |
14 | * This code is released under the GNU General Public License (GPL) |
15 | * |
16 | * This module implements the tty line discipline N_HDLC for use with |
17 | * tty device drivers that support bit-synchronous HDLC communications. |
18 | * |
19 | * All HDLC data is frame oriented which means: |
20 | * |
21 | * 1. tty write calls represent one complete transmit frame of data |
22 | * The device driver should accept the complete frame or none of |
23 | * the frame (busy) in the write method. Each write call should have |
24 | * a byte count in the range of 2-65535 bytes (2 is min HDLC frame |
25 | * with 1 addr byte and 1 ctrl byte). The max byte count of 65535 |
26 | * should include any crc bytes required. For example, when using |
27 | * CCITT CRC32, 4 crc bytes are required, so the maximum size frame |
28 | * the application may transmit is limited to 65531 bytes. For CCITT |
29 | * CRC16, the maximum application frame size would be 65533. |
30 | * |
31 | * |
32 | * 2. receive callbacks from the device driver represents |
33 | * one received frame. The device driver should bypass |
34 | * the tty flip buffer and call the line discipline receive |
35 | * callback directly to avoid fragmenting or concatenating |
36 | * multiple frames into a single receive callback. |
37 | * |
38 | * The HDLC line discipline queues the receive frames in separate |
39 | * buffers so complete receive frames can be returned by the |
40 | * tty read calls. |
41 | * |
42 | * 3. tty read calls returns an entire frame of data or nothing. |
43 | * |
44 | * 4. all send and receive data is considered raw. No processing |
45 | * or translation is performed by the line discipline, regardless |
46 | * of the tty flags |
47 | * |
48 | * 5. When line discipline is queried for the amount of receive |
49 | * data available (FIOC), 0 is returned if no data available, |
50 | * otherwise the count of the next available frame is returned. |
51 | * (instead of the sum of all received frame counts). |
52 | * |
53 | * These conventions allow the standard tty programming interface |
54 | * to be used for synchronous HDLC applications when used with |
55 | * this line discipline (or another line discipline that is frame |
56 | * oriented such as N_PPP). |
57 | * |
58 | * The SyncLink driver (synclink.c) implements both asynchronous |
59 | * (using standard line discipline N_TTY) and synchronous HDLC |
60 | * (using N_HDLC) communications, with the latter using the above |
61 | * conventions. |
62 | * |
63 | * This implementation is very basic and does not maintain |
64 | * any statistics. The main point is to enforce the raw data |
65 | * and frame orientation of HDLC communications. |
66 | * |
67 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED |
68 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
69 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
70 | * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, |
71 | * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
72 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
73 | * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
74 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
75 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
76 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
77 | * OF THE POSSIBILITY OF SUCH DAMAGE. |
78 | */ |
79 | |
80 | #define HDLC_MAGIC 0x239e |
81 | |
82 | #include <linux/module.h> |
83 | #include <linux/init.h> |
84 | #include <linux/kernel.h> |
85 | #include <linux/sched.h> |
86 | #include <linux/types.h> |
87 | #include <linux/fcntl.h> |
88 | #include <linux/interrupt.h> |
89 | #include <linux/ptrace.h> |
90 | |
91 | #undef VERSION |
92 | #define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch)) |
93 | |
94 | #include <linux/poll.h> |
95 | #include <linux/in.h> |
96 | #include <linux/ioctl.h> |
97 | #include <linux/slab.h> |
98 | #include <linux/tty.h> |
99 | #include <linux/errno.h> |
100 | #include <linux/string.h> /* used in new tty drivers */ |
101 | #include <linux/signal.h> /* used in new tty drivers */ |
102 | #include <linux/if.h> |
103 | #include <linux/bitops.h> |
104 | |
105 | #include <asm/termios.h> |
106 | #include <asm/uaccess.h> |
107 | |
108 | /* |
109 | * Buffers for individual HDLC frames |
110 | */ |
111 | #define MAX_HDLC_FRAME_SIZE 65535 |
112 | #define DEFAULT_RX_BUF_COUNT 10 |
113 | #define MAX_RX_BUF_COUNT 60 |
114 | #define DEFAULT_TX_BUF_COUNT 3 |
115 | |
116 | struct n_hdlc_buf { |
117 | struct n_hdlc_buf *link; |
118 | int count; |
119 | char buf[1]; |
120 | }; |
121 | |
122 | #define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe) |
123 | |
124 | struct n_hdlc_buf_list { |
125 | struct n_hdlc_buf *head; |
126 | struct n_hdlc_buf *tail; |
127 | int count; |
128 | spinlock_t spinlock; |
129 | }; |
130 | |
131 | /** |
132 | * struct n_hdlc - per device instance data structure |
133 | * @magic - magic value for structure |
134 | * @flags - miscellaneous control flags |
135 | * @tty - ptr to TTY structure |
136 | * @backup_tty - TTY to use if tty gets closed |
137 | * @tbusy - reentrancy flag for tx wakeup code |
138 | * @woke_up - FIXME: describe this field |
139 | * @tbuf - currently transmitting tx buffer |
140 | * @tx_buf_list - list of pending transmit frame buffers |
141 | * @rx_buf_list - list of received frame buffers |
142 | * @tx_free_buf_list - list unused transmit frame buffers |
143 | * @rx_free_buf_list - list unused received frame buffers |
144 | */ |
145 | struct n_hdlc { |
146 | int magic; |
147 | __u32 flags; |
148 | struct tty_struct *tty; |
149 | struct tty_struct *backup_tty; |
150 | int tbusy; |
151 | int woke_up; |
152 | struct n_hdlc_buf *tbuf; |
153 | struct n_hdlc_buf_list tx_buf_list; |
154 | struct n_hdlc_buf_list rx_buf_list; |
155 | struct n_hdlc_buf_list tx_free_buf_list; |
156 | struct n_hdlc_buf_list rx_free_buf_list; |
157 | }; |
158 | |
159 | /* |
160 | * HDLC buffer list manipulation functions |
161 | */ |
162 | static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list); |
163 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, |
164 | struct n_hdlc_buf *buf); |
165 | static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list); |
166 | |
167 | /* Local functions */ |
168 | |
169 | static struct n_hdlc *n_hdlc_alloc (void); |
170 | |
171 | /* debug level can be set by insmod for debugging purposes */ |
172 | #define DEBUG_LEVEL_INFO 1 |
173 | static int debuglevel; |
174 | |
175 | /* max frame size for memory allocations */ |
176 | static int maxframe = 4096; |
177 | |
178 | /* TTY callbacks */ |
179 | |
180 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, |
181 | __u8 __user *buf, size_t nr); |
182 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, |
183 | const unsigned char *buf, size_t nr); |
184 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, |
185 | unsigned int cmd, unsigned long arg); |
186 | static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, |
187 | poll_table *wait); |
188 | static int n_hdlc_tty_open(struct tty_struct *tty); |
189 | static void n_hdlc_tty_close(struct tty_struct *tty); |
190 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp, |
191 | char *fp, int count); |
192 | static void n_hdlc_tty_wakeup(struct tty_struct *tty); |
193 | |
194 | #define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f))) |
195 | |
196 | #define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data)) |
197 | #define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty) |
198 | |
199 | static void flush_rx_queue(struct tty_struct *tty) |
200 | { |
201 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); |
202 | struct n_hdlc_buf *buf; |
203 | |
204 | while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list))) |
205 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf); |
206 | } |
207 | |
208 | static void flush_tx_queue(struct tty_struct *tty) |
209 | { |
210 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); |
211 | struct n_hdlc_buf *buf; |
212 | unsigned long flags; |
213 | |
214 | while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list))) |
215 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf); |
216 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); |
217 | if (n_hdlc->tbuf) { |
218 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, n_hdlc->tbuf); |
219 | n_hdlc->tbuf = NULL; |
220 | } |
221 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); |
222 | } |
223 | |
224 | static struct tty_ldisc_ops n_hdlc_ldisc = { |
225 | .owner = THIS_MODULE, |
226 | .magic = TTY_LDISC_MAGIC, |
227 | .name = "hdlc", |
228 | .open = n_hdlc_tty_open, |
229 | .close = n_hdlc_tty_close, |
230 | .read = n_hdlc_tty_read, |
231 | .write = n_hdlc_tty_write, |
232 | .ioctl = n_hdlc_tty_ioctl, |
233 | .poll = n_hdlc_tty_poll, |
234 | .receive_buf = n_hdlc_tty_receive, |
235 | .write_wakeup = n_hdlc_tty_wakeup, |
236 | .flush_buffer = flush_rx_queue, |
237 | }; |
238 | |
239 | /** |
240 | * n_hdlc_release - release an n_hdlc per device line discipline info structure |
241 | * @n_hdlc - per device line discipline info structure |
242 | */ |
243 | static void n_hdlc_release(struct n_hdlc *n_hdlc) |
244 | { |
245 | struct tty_struct *tty = n_hdlc2tty (n_hdlc); |
246 | struct n_hdlc_buf *buf; |
247 | |
248 | if (debuglevel >= DEBUG_LEVEL_INFO) |
249 | printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__); |
250 | |
251 | /* Ensure that the n_hdlcd process is not hanging on select()/poll() */ |
252 | wake_up_interruptible (&tty->read_wait); |
253 | wake_up_interruptible (&tty->write_wait); |
254 | |
255 | if (tty->disc_data == n_hdlc) |
256 | tty->disc_data = NULL; /* Break the tty->n_hdlc link */ |
257 | |
258 | /* Release transmit and receive buffers */ |
259 | for(;;) { |
260 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); |
261 | if (buf) { |
262 | kfree(buf); |
263 | } else |
264 | break; |
265 | } |
266 | for(;;) { |
267 | buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); |
268 | if (buf) { |
269 | kfree(buf); |
270 | } else |
271 | break; |
272 | } |
273 | for(;;) { |
274 | buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); |
275 | if (buf) { |
276 | kfree(buf); |
277 | } else |
278 | break; |
279 | } |
280 | for(;;) { |
281 | buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); |
282 | if (buf) { |
283 | kfree(buf); |
284 | } else |
285 | break; |
286 | } |
287 | kfree(n_hdlc->tbuf); |
288 | kfree(n_hdlc); |
289 | |
290 | } /* end of n_hdlc_release() */ |
291 | |
292 | /** |
293 | * n_hdlc_tty_close - line discipline close |
294 | * @tty - pointer to tty info structure |
295 | * |
296 | * Called when the line discipline is changed to something |
297 | * else, the tty is closed, or the tty detects a hangup. |
298 | */ |
299 | static void n_hdlc_tty_close(struct tty_struct *tty) |
300 | { |
301 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); |
302 | |
303 | if (debuglevel >= DEBUG_LEVEL_INFO) |
304 | printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__); |
305 | |
306 | if (n_hdlc != NULL) { |
307 | if (n_hdlc->magic != HDLC_MAGIC) { |
308 | printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n"); |
309 | return; |
310 | } |
311 | #if defined(TTY_NO_WRITE_SPLIT) |
312 | clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags); |
313 | #endif |
314 | tty->disc_data = NULL; |
315 | if (tty == n_hdlc->backup_tty) |
316 | n_hdlc->backup_tty = NULL; |
317 | if (tty != n_hdlc->tty) |
318 | return; |
319 | if (n_hdlc->backup_tty) { |
320 | n_hdlc->tty = n_hdlc->backup_tty; |
321 | } else { |
322 | n_hdlc_release (n_hdlc); |
323 | } |
324 | } |
325 | |
326 | if (debuglevel >= DEBUG_LEVEL_INFO) |
327 | printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__); |
328 | |
329 | } /* end of n_hdlc_tty_close() */ |
330 | |
331 | /** |
332 | * n_hdlc_tty_open - called when line discipline changed to n_hdlc |
333 | * @tty - pointer to tty info structure |
334 | * |
335 | * Returns 0 if success, otherwise error code |
336 | */ |
337 | static int n_hdlc_tty_open (struct tty_struct *tty) |
338 | { |
339 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); |
340 | |
341 | if (debuglevel >= DEBUG_LEVEL_INFO) |
342 | printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n", |
343 | __FILE__,__LINE__, |
344 | tty->name); |
345 | |
346 | /* There should not be an existing table for this slot. */ |
347 | if (n_hdlc) { |
348 | printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" ); |
349 | return -EEXIST; |
350 | } |
351 | |
352 | n_hdlc = n_hdlc_alloc(); |
353 | if (!n_hdlc) { |
354 | printk (KERN_ERR "n_hdlc_alloc failed\n"); |
355 | return -ENFILE; |
356 | } |
357 | |
358 | tty->disc_data = n_hdlc; |
359 | n_hdlc->tty = tty; |
360 | tty->receive_room = 65536; |
361 | |
362 | #if defined(TTY_NO_WRITE_SPLIT) |
363 | /* change tty_io write() to not split large writes into 8K chunks */ |
364 | set_bit(TTY_NO_WRITE_SPLIT,&tty->flags); |
365 | #endif |
366 | |
367 | /* flush receive data from driver */ |
368 | tty_driver_flush_buffer(tty); |
369 | |
370 | if (debuglevel >= DEBUG_LEVEL_INFO) |
371 | printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__); |
372 | |
373 | return 0; |
374 | |
375 | } /* end of n_tty_hdlc_open() */ |
376 | |
377 | /** |
378 | * n_hdlc_send_frames - send frames on pending send buffer list |
379 | * @n_hdlc - pointer to ldisc instance data |
380 | * @tty - pointer to tty instance data |
381 | * |
382 | * Send frames on pending send buffer list until the driver does not accept a |
383 | * frame (busy) this function is called after adding a frame to the send buffer |
384 | * list and by the tty wakeup callback. |
385 | */ |
386 | static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty) |
387 | { |
388 | register int actual; |
389 | unsigned long flags; |
390 | struct n_hdlc_buf *tbuf; |
391 | |
392 | if (debuglevel >= DEBUG_LEVEL_INFO) |
393 | printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__,__LINE__); |
394 | check_again: |
395 | |
396 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); |
397 | if (n_hdlc->tbusy) { |
398 | n_hdlc->woke_up = 1; |
399 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); |
400 | return; |
401 | } |
402 | n_hdlc->tbusy = 1; |
403 | n_hdlc->woke_up = 0; |
404 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); |
405 | |
406 | /* get current transmit buffer or get new transmit */ |
407 | /* buffer from list of pending transmit buffers */ |
408 | |
409 | tbuf = n_hdlc->tbuf; |
410 | if (!tbuf) |
411 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); |
412 | |
413 | while (tbuf) { |
414 | if (debuglevel >= DEBUG_LEVEL_INFO) |
415 | printk("%s(%d)sending frame %p, count=%d\n", |
416 | __FILE__,__LINE__,tbuf,tbuf->count); |
417 | |
418 | /* Send the next block of data to device */ |
419 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
420 | actual = tty->ops->write(tty, tbuf->buf, tbuf->count); |
421 | |
422 | /* rollback was possible and has been done */ |
423 | if (actual == -ERESTARTSYS) { |
424 | n_hdlc->tbuf = tbuf; |
425 | break; |
426 | } |
427 | /* if transmit error, throw frame away by */ |
428 | /* pretending it was accepted by driver */ |
429 | if (actual < 0) |
430 | actual = tbuf->count; |
431 | |
432 | if (actual == tbuf->count) { |
433 | if (debuglevel >= DEBUG_LEVEL_INFO) |
434 | printk("%s(%d)frame %p completed\n", |
435 | __FILE__,__LINE__,tbuf); |
436 | |
437 | /* free current transmit buffer */ |
438 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf); |
439 | |
440 | /* this tx buffer is done */ |
441 | n_hdlc->tbuf = NULL; |
442 | |
443 | /* wait up sleeping writers */ |
444 | wake_up_interruptible(&tty->write_wait); |
445 | |
446 | /* get next pending transmit buffer */ |
447 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); |
448 | } else { |
449 | if (debuglevel >= DEBUG_LEVEL_INFO) |
450 | printk("%s(%d)frame %p pending\n", |
451 | __FILE__,__LINE__,tbuf); |
452 | |
453 | /* buffer not accepted by driver */ |
454 | /* set this buffer as pending buffer */ |
455 | n_hdlc->tbuf = tbuf; |
456 | break; |
457 | } |
458 | } |
459 | |
460 | if (!tbuf) |
461 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
462 | |
463 | /* Clear the re-entry flag */ |
464 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); |
465 | n_hdlc->tbusy = 0; |
466 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); |
467 | |
468 | if (n_hdlc->woke_up) |
469 | goto check_again; |
470 | |
471 | if (debuglevel >= DEBUG_LEVEL_INFO) |
472 | printk("%s(%d)n_hdlc_send_frames() exit\n",__FILE__,__LINE__); |
473 | |
474 | } /* end of n_hdlc_send_frames() */ |
475 | |
476 | /** |
477 | * n_hdlc_tty_wakeup - Callback for transmit wakeup |
478 | * @tty - pointer to associated tty instance data |
479 | * |
480 | * Called when low level device driver can accept more send data. |
481 | */ |
482 | static void n_hdlc_tty_wakeup(struct tty_struct *tty) |
483 | { |
484 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); |
485 | |
486 | if (debuglevel >= DEBUG_LEVEL_INFO) |
487 | printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__,__LINE__); |
488 | |
489 | if (!n_hdlc) |
490 | return; |
491 | |
492 | if (tty != n_hdlc->tty) { |
493 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
494 | return; |
495 | } |
496 | |
497 | n_hdlc_send_frames (n_hdlc, tty); |
498 | |
499 | } /* end of n_hdlc_tty_wakeup() */ |
500 | |
501 | /** |
502 | * n_hdlc_tty_receive - Called by tty driver when receive data is available |
503 | * @tty - pointer to tty instance data |
504 | * @data - pointer to received data |
505 | * @flags - pointer to flags for data |
506 | * @count - count of received data in bytes |
507 | * |
508 | * Called by tty low level driver when receive data is available. Data is |
509 | * interpreted as one HDLC frame. |
510 | */ |
511 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data, |
512 | char *flags, int count) |
513 | { |
514 | register struct n_hdlc *n_hdlc = tty2n_hdlc (tty); |
515 | register struct n_hdlc_buf *buf; |
516 | |
517 | if (debuglevel >= DEBUG_LEVEL_INFO) |
518 | printk("%s(%d)n_hdlc_tty_receive() called count=%d\n", |
519 | __FILE__,__LINE__, count); |
520 | |
521 | /* This can happen if stuff comes in on the backup tty */ |
522 | if (!n_hdlc || tty != n_hdlc->tty) |
523 | return; |
524 | |
525 | /* verify line is using HDLC discipline */ |
526 | if (n_hdlc->magic != HDLC_MAGIC) { |
527 | printk("%s(%d) line not using HDLC discipline\n", |
528 | __FILE__,__LINE__); |
529 | return; |
530 | } |
531 | |
532 | if ( count>maxframe ) { |
533 | if (debuglevel >= DEBUG_LEVEL_INFO) |
534 | printk("%s(%d) rx count>maxframesize, data discarded\n", |
535 | __FILE__,__LINE__); |
536 | return; |
537 | } |
538 | |
539 | /* get a free HDLC buffer */ |
540 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); |
541 | if (!buf) { |
542 | /* no buffers in free list, attempt to allocate another rx buffer */ |
543 | /* unless the maximum count has been reached */ |
544 | if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT) |
545 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_ATOMIC); |
546 | } |
547 | |
548 | if (!buf) { |
549 | if (debuglevel >= DEBUG_LEVEL_INFO) |
550 | printk("%s(%d) no more rx buffers, data discarded\n", |
551 | __FILE__,__LINE__); |
552 | return; |
553 | } |
554 | |
555 | /* copy received data to HDLC buffer */ |
556 | memcpy(buf->buf,data,count); |
557 | buf->count=count; |
558 | |
559 | /* add HDLC buffer to list of received frames */ |
560 | n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf); |
561 | |
562 | /* wake up any blocked reads and perform async signalling */ |
563 | wake_up_interruptible (&tty->read_wait); |
564 | if (n_hdlc->tty->fasync != NULL) |
565 | kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN); |
566 | |
567 | } /* end of n_hdlc_tty_receive() */ |
568 | |
569 | /** |
570 | * n_hdlc_tty_read - Called to retrieve one frame of data (if available) |
571 | * @tty - pointer to tty instance data |
572 | * @file - pointer to open file object |
573 | * @buf - pointer to returned data buffer |
574 | * @nr - size of returned data buffer |
575 | * |
576 | * Returns the number of bytes returned or error code. |
577 | */ |
578 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, |
579 | __u8 __user *buf, size_t nr) |
580 | { |
581 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); |
582 | int ret = 0; |
583 | struct n_hdlc_buf *rbuf; |
584 | DECLARE_WAITQUEUE(wait, current); |
585 | |
586 | if (debuglevel >= DEBUG_LEVEL_INFO) |
587 | printk("%s(%d)n_hdlc_tty_read() called\n",__FILE__,__LINE__); |
588 | |
589 | /* Validate the pointers */ |
590 | if (!n_hdlc) |
591 | return -EIO; |
592 | |
593 | /* verify user access to buffer */ |
594 | if (!access_ok(VERIFY_WRITE, buf, nr)) { |
595 | printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user " |
596 | "buffer\n", __FILE__, __LINE__); |
597 | return -EFAULT; |
598 | } |
599 | |
600 | add_wait_queue(&tty->read_wait, &wait); |
601 | |
602 | for (;;) { |
603 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { |
604 | ret = -EIO; |
605 | break; |
606 | } |
607 | if (tty_hung_up_p(file)) |
608 | break; |
609 | |
610 | set_current_state(TASK_INTERRUPTIBLE); |
611 | |
612 | rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); |
613 | if (rbuf) { |
614 | if (rbuf->count > nr) { |
615 | /* too large for caller's buffer */ |
616 | ret = -EOVERFLOW; |
617 | } else { |
618 | if (copy_to_user(buf, rbuf->buf, rbuf->count)) |
619 | ret = -EFAULT; |
620 | else |
621 | ret = rbuf->count; |
622 | } |
623 | |
624 | if (n_hdlc->rx_free_buf_list.count > |
625 | DEFAULT_RX_BUF_COUNT) |
626 | kfree(rbuf); |
627 | else |
628 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, rbuf); |
629 | break; |
630 | } |
631 | |
632 | /* no data */ |
633 | if (file->f_flags & O_NONBLOCK) { |
634 | ret = -EAGAIN; |
635 | break; |
636 | } |
637 | |
638 | schedule(); |
639 | |
640 | if (signal_pending(current)) { |
641 | ret = -EINTR; |
642 | break; |
643 | } |
644 | } |
645 | |
646 | remove_wait_queue(&tty->read_wait, &wait); |
647 | __set_current_state(TASK_RUNNING); |
648 | |
649 | return ret; |
650 | |
651 | } /* end of n_hdlc_tty_read() */ |
652 | |
653 | /** |
654 | * n_hdlc_tty_write - write a single frame of data to device |
655 | * @tty - pointer to associated tty device instance data |
656 | * @file - pointer to file object data |
657 | * @data - pointer to transmit data (one frame) |
658 | * @count - size of transmit frame in bytes |
659 | * |
660 | * Returns the number of bytes written (or error code). |
661 | */ |
662 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, |
663 | const unsigned char *data, size_t count) |
664 | { |
665 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); |
666 | int error = 0; |
667 | DECLARE_WAITQUEUE(wait, current); |
668 | struct n_hdlc_buf *tbuf; |
669 | |
670 | if (debuglevel >= DEBUG_LEVEL_INFO) |
671 | printk("%s(%d)n_hdlc_tty_write() called count=%Zd\n", |
672 | __FILE__,__LINE__,count); |
673 | |
674 | /* Verify pointers */ |
675 | if (!n_hdlc) |
676 | return -EIO; |
677 | |
678 | if (n_hdlc->magic != HDLC_MAGIC) |
679 | return -EIO; |
680 | |
681 | /* verify frame size */ |
682 | if (count > maxframe ) { |
683 | if (debuglevel & DEBUG_LEVEL_INFO) |
684 | printk (KERN_WARNING |
685 | "n_hdlc_tty_write: truncating user packet " |
686 | "from %lu to %d\n", (unsigned long) count, |
687 | maxframe ); |
688 | count = maxframe; |
689 | } |
690 | |
691 | add_wait_queue(&tty->write_wait, &wait); |
692 | |
693 | for (;;) { |
694 | set_current_state(TASK_INTERRUPTIBLE); |
695 | |
696 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); |
697 | if (tbuf) |
698 | break; |
699 | |
700 | if (file->f_flags & O_NONBLOCK) { |
701 | error = -EAGAIN; |
702 | break; |
703 | } |
704 | schedule(); |
705 | |
706 | n_hdlc = tty2n_hdlc (tty); |
707 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || |
708 | tty != n_hdlc->tty) { |
709 | printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc); |
710 | error = -EIO; |
711 | break; |
712 | } |
713 | |
714 | if (signal_pending(current)) { |
715 | error = -EINTR; |
716 | break; |
717 | } |
718 | } |
719 | |
720 | __set_current_state(TASK_RUNNING); |
721 | remove_wait_queue(&tty->write_wait, &wait); |
722 | |
723 | if (!error) { |
724 | /* Retrieve the user's buffer */ |
725 | memcpy(tbuf->buf, data, count); |
726 | |
727 | /* Send the data */ |
728 | tbuf->count = error = count; |
729 | n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf); |
730 | n_hdlc_send_frames(n_hdlc,tty); |
731 | } |
732 | |
733 | return error; |
734 | |
735 | } /* end of n_hdlc_tty_write() */ |
736 | |
737 | /** |
738 | * n_hdlc_tty_ioctl - process IOCTL system call for the tty device. |
739 | * @tty - pointer to tty instance data |
740 | * @file - pointer to open file object for device |
741 | * @cmd - IOCTL command code |
742 | * @arg - argument for IOCTL call (cmd dependent) |
743 | * |
744 | * Returns command dependent result. |
745 | */ |
746 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, |
747 | unsigned int cmd, unsigned long arg) |
748 | { |
749 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); |
750 | int error = 0; |
751 | int count; |
752 | unsigned long flags; |
753 | |
754 | if (debuglevel >= DEBUG_LEVEL_INFO) |
755 | printk("%s(%d)n_hdlc_tty_ioctl() called %d\n", |
756 | __FILE__,__LINE__,cmd); |
757 | |
758 | /* Verify the status of the device */ |
759 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC) |
760 | return -EBADF; |
761 | |
762 | switch (cmd) { |
763 | case FIONREAD: |
764 | /* report count of read data available */ |
765 | /* in next available frame (if any) */ |
766 | spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock,flags); |
767 | if (n_hdlc->rx_buf_list.head) |
768 | count = n_hdlc->rx_buf_list.head->count; |
769 | else |
770 | count = 0; |
771 | spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags); |
772 | error = put_user(count, (int __user *)arg); |
773 | break; |
774 | |
775 | case TIOCOUTQ: |
776 | /* get the pending tx byte count in the driver */ |
777 | count = tty_chars_in_buffer(tty); |
778 | /* add size of next output frame in queue */ |
779 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags); |
780 | if (n_hdlc->tx_buf_list.head) |
781 | count += n_hdlc->tx_buf_list.head->count; |
782 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock,flags); |
783 | error = put_user(count, (int __user *)arg); |
784 | break; |
785 | |
786 | case TCFLSH: |
787 | switch (arg) { |
788 | case TCIOFLUSH: |
789 | case TCOFLUSH: |
790 | flush_tx_queue(tty); |
791 | } |
792 | /* fall through to default */ |
793 | |
794 | default: |
795 | error = n_tty_ioctl_helper(tty, file, cmd, arg); |
796 | break; |
797 | } |
798 | return error; |
799 | |
800 | } /* end of n_hdlc_tty_ioctl() */ |
801 | |
802 | /** |
803 | * n_hdlc_tty_poll - TTY callback for poll system call |
804 | * @tty - pointer to tty instance data |
805 | * @filp - pointer to open file object for device |
806 | * @poll_table - wait queue for operations |
807 | * |
808 | * Determine which operations (read/write) will not block and return info |
809 | * to caller. |
810 | * Returns a bit mask containing info on which ops will not block. |
811 | */ |
812 | static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, |
813 | poll_table *wait) |
814 | { |
815 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); |
816 | unsigned int mask = 0; |
817 | |
818 | if (debuglevel >= DEBUG_LEVEL_INFO) |
819 | printk("%s(%d)n_hdlc_tty_poll() called\n",__FILE__,__LINE__); |
820 | |
821 | if (n_hdlc && n_hdlc->magic == HDLC_MAGIC && tty == n_hdlc->tty) { |
822 | /* queue current process into any wait queue that */ |
823 | /* may awaken in the future (read and write) */ |
824 | |
825 | poll_wait(filp, &tty->read_wait, wait); |
826 | poll_wait(filp, &tty->write_wait, wait); |
827 | |
828 | /* set bits for operations that won't block */ |
829 | if (n_hdlc->rx_buf_list.head) |
830 | mask |= POLLIN | POLLRDNORM; /* readable */ |
831 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) |
832 | mask |= POLLHUP; |
833 | if (tty_hung_up_p(filp)) |
834 | mask |= POLLHUP; |
835 | if (!tty_is_writelocked(tty) && |
836 | n_hdlc->tx_free_buf_list.head) |
837 | mask |= POLLOUT | POLLWRNORM; /* writable */ |
838 | } |
839 | return mask; |
840 | } /* end of n_hdlc_tty_poll() */ |
841 | |
842 | /** |
843 | * n_hdlc_alloc - allocate an n_hdlc instance data structure |
844 | * |
845 | * Returns a pointer to newly created structure if success, otherwise %NULL |
846 | */ |
847 | static struct n_hdlc *n_hdlc_alloc(void) |
848 | { |
849 | struct n_hdlc_buf *buf; |
850 | int i; |
851 | struct n_hdlc *n_hdlc = kmalloc(sizeof(*n_hdlc), GFP_KERNEL); |
852 | |
853 | if (!n_hdlc) |
854 | return NULL; |
855 | |
856 | memset(n_hdlc, 0, sizeof(*n_hdlc)); |
857 | |
858 | n_hdlc_buf_list_init(&n_hdlc->rx_free_buf_list); |
859 | n_hdlc_buf_list_init(&n_hdlc->tx_free_buf_list); |
860 | n_hdlc_buf_list_init(&n_hdlc->rx_buf_list); |
861 | n_hdlc_buf_list_init(&n_hdlc->tx_buf_list); |
862 | |
863 | /* allocate free rx buffer list */ |
864 | for(i=0;i<DEFAULT_RX_BUF_COUNT;i++) { |
865 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); |
866 | if (buf) |
867 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,buf); |
868 | else if (debuglevel >= DEBUG_LEVEL_INFO) |
869 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for rx buffer %d\n",__FILE__,__LINE__, i); |
870 | } |
871 | |
872 | /* allocate free tx buffer list */ |
873 | for(i=0;i<DEFAULT_TX_BUF_COUNT;i++) { |
874 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); |
875 | if (buf) |
876 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list,buf); |
877 | else if (debuglevel >= DEBUG_LEVEL_INFO) |
878 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for tx buffer %d\n",__FILE__,__LINE__, i); |
879 | } |
880 | |
881 | /* Initialize the control block */ |
882 | n_hdlc->magic = HDLC_MAGIC; |
883 | n_hdlc->flags = 0; |
884 | |
885 | return n_hdlc; |
886 | |
887 | } /* end of n_hdlc_alloc() */ |
888 | |
889 | /** |
890 | * n_hdlc_buf_list_init - initialize specified HDLC buffer list |
891 | * @list - pointer to buffer list |
892 | */ |
893 | static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list) |
894 | { |
895 | memset(list, 0, sizeof(*list)); |
896 | spin_lock_init(&list->spinlock); |
897 | } /* end of n_hdlc_buf_list_init() */ |
898 | |
899 | /** |
900 | * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list |
901 | * @list - pointer to buffer list |
902 | * @buf - pointer to buffer |
903 | */ |
904 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, |
905 | struct n_hdlc_buf *buf) |
906 | { |
907 | unsigned long flags; |
908 | spin_lock_irqsave(&list->spinlock,flags); |
909 | |
910 | buf->link=NULL; |
911 | if (list->tail) |
912 | list->tail->link = buf; |
913 | else |
914 | list->head = buf; |
915 | list->tail = buf; |
916 | (list->count)++; |
917 | |
918 | spin_unlock_irqrestore(&list->spinlock,flags); |
919 | |
920 | } /* end of n_hdlc_buf_put() */ |
921 | |
922 | /** |
923 | * n_hdlc_buf_get - remove and return an HDLC buffer from list |
924 | * @list - pointer to HDLC buffer list |
925 | * |
926 | * Remove and return an HDLC buffer from the head of the specified HDLC buffer |
927 | * list. |
928 | * Returns a pointer to HDLC buffer if available, otherwise %NULL. |
929 | */ |
930 | static struct n_hdlc_buf* n_hdlc_buf_get(struct n_hdlc_buf_list *list) |
931 | { |
932 | unsigned long flags; |
933 | struct n_hdlc_buf *buf; |
934 | spin_lock_irqsave(&list->spinlock,flags); |
935 | |
936 | buf = list->head; |
937 | if (buf) { |
938 | list->head = buf->link; |
939 | (list->count)--; |
940 | } |
941 | if (!list->head) |
942 | list->tail = NULL; |
943 | |
944 | spin_unlock_irqrestore(&list->spinlock,flags); |
945 | return buf; |
946 | |
947 | } /* end of n_hdlc_buf_get() */ |
948 | |
949 | static char hdlc_banner[] __initdata = |
950 | KERN_INFO "HDLC line discipline maxframe=%u\n"; |
951 | static char hdlc_register_ok[] __initdata = |
952 | KERN_INFO "N_HDLC line discipline registered.\n"; |
953 | static char hdlc_register_fail[] __initdata = |
954 | KERN_ERR "error registering line discipline: %d\n"; |
955 | static char hdlc_init_fail[] __initdata = |
956 | KERN_INFO "N_HDLC: init failure %d\n"; |
957 | |
958 | static int __init n_hdlc_init(void) |
959 | { |
960 | int status; |
961 | |
962 | /* range check maxframe arg */ |
963 | if (maxframe < 4096) |
964 | maxframe = 4096; |
965 | else if (maxframe > 65535) |
966 | maxframe = 65535; |
967 | |
968 | printk(hdlc_banner, maxframe); |
969 | |
970 | status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc); |
971 | if (!status) |
972 | printk(hdlc_register_ok); |
973 | else |
974 | printk(hdlc_register_fail, status); |
975 | |
976 | if (status) |
977 | printk(hdlc_init_fail, status); |
978 | return status; |
979 | |
980 | } /* end of init_module() */ |
981 | |
982 | static char hdlc_unregister_ok[] __exitdata = |
983 | KERN_INFO "N_HDLC: line discipline unregistered\n"; |
984 | static char hdlc_unregister_fail[] __exitdata = |
985 | KERN_ERR "N_HDLC: can't unregister line discipline (err = %d)\n"; |
986 | |
987 | static void __exit n_hdlc_exit(void) |
988 | { |
989 | /* Release tty registration of line discipline */ |
990 | int status = tty_unregister_ldisc(N_HDLC); |
991 | |
992 | if (status) |
993 | printk(hdlc_unregister_fail, status); |
994 | else |
995 | printk(hdlc_unregister_ok); |
996 | } |
997 | |
998 | module_init(n_hdlc_init); |
999 | module_exit(n_hdlc_exit); |
1000 | |
1001 | MODULE_LICENSE("GPL"); |
1002 | MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com"); |
1003 | module_param(debuglevel, int, 0); |
1004 | module_param(maxframe, int, 0); |
1005 | MODULE_ALIAS_LDISC(N_HDLC); |
1006 |
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