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1da177e4 LT |
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 | * $Id: n_hdlc.c,v 4.8 2003/05/06 21:18:51 paulkf Exp $ | |
14 | * | |
15 | * This code is released under the GNU General Public License (GPL) | |
16 | * | |
17 | * This module implements the tty line discipline N_HDLC for use with | |
18 | * tty device drivers that support bit-synchronous HDLC communications. | |
19 | * | |
20 | * All HDLC data is frame oriented which means: | |
21 | * | |
22 | * 1. tty write calls represent one complete transmit frame of data | |
23 | * The device driver should accept the complete frame or none of | |
24 | * the frame (busy) in the write method. Each write call should have | |
25 | * a byte count in the range of 2-65535 bytes (2 is min HDLC frame | |
26 | * with 1 addr byte and 1 ctrl byte). The max byte count of 65535 | |
27 | * should include any crc bytes required. For example, when using | |
28 | * CCITT CRC32, 4 crc bytes are required, so the maximum size frame | |
29 | * the application may transmit is limited to 65531 bytes. For CCITT | |
30 | * CRC16, the maximum application frame size would be 65533. | |
31 | * | |
32 | * | |
33 | * 2. receive callbacks from the device driver represents | |
34 | * one received frame. The device driver should bypass | |
35 | * the tty flip buffer and call the line discipline receive | |
36 | * callback directly to avoid fragmenting or concatenating | |
37 | * multiple frames into a single receive callback. | |
38 | * | |
39 | * The HDLC line discipline queues the receive frames in separate | |
40 | * buffers so complete receive frames can be returned by the | |
41 | * tty read calls. | |
42 | * | |
43 | * 3. tty read calls returns an entire frame of data or nothing. | |
44 | * | |
45 | * 4. all send and receive data is considered raw. No processing | |
46 | * or translation is performed by the line discipline, regardless | |
47 | * of the tty flags | |
48 | * | |
49 | * 5. When line discipline is queried for the amount of receive | |
50 | * data available (FIOC), 0 is returned if no data available, | |
51 | * otherwise the count of the next available frame is returned. | |
52 | * (instead of the sum of all received frame counts). | |
53 | * | |
54 | * These conventions allow the standard tty programming interface | |
55 | * to be used for synchronous HDLC applications when used with | |
56 | * this line discipline (or another line discipline that is frame | |
57 | * oriented such as N_PPP). | |
58 | * | |
59 | * The SyncLink driver (synclink.c) implements both asynchronous | |
60 | * (using standard line discipline N_TTY) and synchronous HDLC | |
61 | * (using N_HDLC) communications, with the latter using the above | |
62 | * conventions. | |
63 | * | |
64 | * This implementation is very basic and does not maintain | |
65 | * any statistics. The main point is to enforce the raw data | |
66 | * and frame orientation of HDLC communications. | |
67 | * | |
68 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED | |
69 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
70 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | |
71 | * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, | |
72 | * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | |
73 | * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | |
74 | * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
75 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
76 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
77 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
78 | * OF THE POSSIBILITY OF SUCH DAMAGE. | |
79 | */ | |
80 | ||
81 | #define HDLC_MAGIC 0x239e | |
82 | #define HDLC_VERSION "$Revision: 4.8 $" | |
83 | ||
1da177e4 LT |
84 | #include <linux/module.h> |
85 | #include <linux/init.h> | |
86 | #include <linux/kernel.h> | |
87 | #include <linux/sched.h> | |
88 | #include <linux/types.h> | |
89 | #include <linux/fcntl.h> | |
90 | #include <linux/interrupt.h> | |
91 | #include <linux/ptrace.h> | |
92 | ||
93 | #undef VERSION | |
94 | #define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch)) | |
95 | ||
96 | #include <linux/poll.h> | |
97 | #include <linux/in.h> | |
98 | #include <linux/ioctl.h> | |
99 | #include <linux/slab.h> | |
100 | #include <linux/tty.h> | |
101 | #include <linux/errno.h> | |
102 | #include <linux/string.h> /* used in new tty drivers */ | |
103 | #include <linux/signal.h> /* used in new tty drivers */ | |
104 | #include <linux/if.h> | |
105 | #include <linux/bitops.h> | |
106 | ||
107 | #include <asm/system.h> | |
108 | #include <asm/termios.h> | |
109 | #include <asm/uaccess.h> | |
110 | ||
111 | /* | |
112 | * Buffers for individual HDLC frames | |
113 | */ | |
114 | #define MAX_HDLC_FRAME_SIZE 65535 | |
115 | #define DEFAULT_RX_BUF_COUNT 10 | |
116 | #define MAX_RX_BUF_COUNT 60 | |
117 | #define DEFAULT_TX_BUF_COUNT 1 | |
118 | ||
119 | struct n_hdlc_buf { | |
120 | struct n_hdlc_buf *link; | |
121 | int count; | |
122 | char buf[1]; | |
123 | }; | |
124 | ||
125 | #define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe) | |
126 | ||
127 | struct n_hdlc_buf_list { | |
128 | struct n_hdlc_buf *head; | |
129 | struct n_hdlc_buf *tail; | |
130 | int count; | |
131 | spinlock_t spinlock; | |
132 | }; | |
133 | ||
134 | /** | |
135 | * struct n_hdlc - per device instance data structure | |
136 | * @magic - magic value for structure | |
137 | * @flags - miscellaneous control flags | |
138 | * @tty - ptr to TTY structure | |
139 | * @backup_tty - TTY to use if tty gets closed | |
140 | * @tbusy - reentrancy flag for tx wakeup code | |
141 | * @woke_up - FIXME: describe this field | |
142 | * @tbuf - currently transmitting tx buffer | |
143 | * @tx_buf_list - list of pending transmit frame buffers | |
144 | * @rx_buf_list - list of received frame buffers | |
145 | * @tx_free_buf_list - list unused transmit frame buffers | |
146 | * @rx_free_buf_list - list unused received frame buffers | |
147 | */ | |
148 | struct n_hdlc { | |
149 | int magic; | |
150 | __u32 flags; | |
151 | struct tty_struct *tty; | |
152 | struct tty_struct *backup_tty; | |
153 | int tbusy; | |
154 | int woke_up; | |
155 | struct n_hdlc_buf *tbuf; | |
156 | struct n_hdlc_buf_list tx_buf_list; | |
157 | struct n_hdlc_buf_list rx_buf_list; | |
158 | struct n_hdlc_buf_list tx_free_buf_list; | |
159 | struct n_hdlc_buf_list rx_free_buf_list; | |
160 | }; | |
161 | ||
162 | /* | |
163 | * HDLC buffer list manipulation functions | |
164 | */ | |
165 | static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list); | |
166 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, | |
167 | struct n_hdlc_buf *buf); | |
168 | static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list); | |
169 | ||
170 | /* Local functions */ | |
171 | ||
172 | static struct n_hdlc *n_hdlc_alloc (void); | |
173 | ||
174 | /* debug level can be set by insmod for debugging purposes */ | |
175 | #define DEBUG_LEVEL_INFO 1 | |
176 | static int debuglevel; | |
177 | ||
178 | /* max frame size for memory allocations */ | |
179 | static int maxframe = 4096; | |
180 | ||
181 | /* TTY callbacks */ | |
182 | ||
183 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
184 | __u8 __user *buf, size_t nr); | |
185 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
186 | const unsigned char *buf, size_t nr); | |
187 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
188 | unsigned int cmd, unsigned long arg); | |
189 | static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, | |
190 | poll_table *wait); | |
191 | static int n_hdlc_tty_open(struct tty_struct *tty); | |
192 | static void n_hdlc_tty_close(struct tty_struct *tty); | |
1da177e4 LT |
193 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp, |
194 | char *fp, int count); | |
195 | static void n_hdlc_tty_wakeup(struct tty_struct *tty); | |
196 | ||
197 | #define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f))) | |
198 | ||
199 | #define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data)) | |
200 | #define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty) | |
201 | ||
202 | static struct tty_ldisc n_hdlc_ldisc = { | |
203 | .owner = THIS_MODULE, | |
204 | .magic = TTY_LDISC_MAGIC, | |
205 | .name = "hdlc", | |
206 | .open = n_hdlc_tty_open, | |
207 | .close = n_hdlc_tty_close, | |
208 | .read = n_hdlc_tty_read, | |
209 | .write = n_hdlc_tty_write, | |
210 | .ioctl = n_hdlc_tty_ioctl, | |
211 | .poll = n_hdlc_tty_poll, | |
212 | .receive_buf = n_hdlc_tty_receive, | |
1da177e4 LT |
213 | .write_wakeup = n_hdlc_tty_wakeup, |
214 | }; | |
215 | ||
216 | /** | |
217 | * n_hdlc_release - release an n_hdlc per device line discipline info structure | |
218 | * @n_hdlc - per device line discipline info structure | |
219 | */ | |
220 | static void n_hdlc_release(struct n_hdlc *n_hdlc) | |
221 | { | |
222 | struct tty_struct *tty = n_hdlc2tty (n_hdlc); | |
223 | struct n_hdlc_buf *buf; | |
224 | ||
225 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
226 | printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__); | |
227 | ||
228 | /* Ensure that the n_hdlcd process is not hanging on select()/poll() */ | |
229 | wake_up_interruptible (&tty->read_wait); | |
230 | wake_up_interruptible (&tty->write_wait); | |
231 | ||
232 | if (tty != NULL && tty->disc_data == n_hdlc) | |
233 | tty->disc_data = NULL; /* Break the tty->n_hdlc link */ | |
234 | ||
235 | /* Release transmit and receive buffers */ | |
236 | for(;;) { | |
237 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); | |
238 | if (buf) { | |
239 | kfree(buf); | |
240 | } else | |
241 | break; | |
242 | } | |
243 | for(;;) { | |
244 | buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); | |
245 | if (buf) { | |
246 | kfree(buf); | |
247 | } else | |
248 | break; | |
249 | } | |
250 | for(;;) { | |
251 | buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); | |
252 | if (buf) { | |
253 | kfree(buf); | |
254 | } else | |
255 | break; | |
256 | } | |
257 | for(;;) { | |
258 | buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
259 | if (buf) { | |
260 | kfree(buf); | |
261 | } else | |
262 | break; | |
263 | } | |
735d5661 | 264 | kfree(n_hdlc->tbuf); |
1da177e4 LT |
265 | kfree(n_hdlc); |
266 | ||
267 | } /* end of n_hdlc_release() */ | |
268 | ||
269 | /** | |
270 | * n_hdlc_tty_close - line discipline close | |
271 | * @tty - pointer to tty info structure | |
272 | * | |
273 | * Called when the line discipline is changed to something | |
274 | * else, the tty is closed, or the tty detects a hangup. | |
275 | */ | |
276 | static void n_hdlc_tty_close(struct tty_struct *tty) | |
277 | { | |
278 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
279 | ||
280 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
281 | printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__); | |
282 | ||
283 | if (n_hdlc != NULL) { | |
284 | if (n_hdlc->magic != HDLC_MAGIC) { | |
285 | printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n"); | |
286 | return; | |
287 | } | |
288 | #if defined(TTY_NO_WRITE_SPLIT) | |
289 | clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags); | |
290 | #endif | |
291 | tty->disc_data = NULL; | |
292 | if (tty == n_hdlc->backup_tty) | |
293 | n_hdlc->backup_tty = NULL; | |
294 | if (tty != n_hdlc->tty) | |
295 | return; | |
296 | if (n_hdlc->backup_tty) { | |
297 | n_hdlc->tty = n_hdlc->backup_tty; | |
298 | } else { | |
299 | n_hdlc_release (n_hdlc); | |
300 | } | |
301 | } | |
302 | ||
303 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
304 | printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__); | |
305 | ||
306 | } /* end of n_hdlc_tty_close() */ | |
307 | ||
308 | /** | |
309 | * n_hdlc_tty_open - called when line discipline changed to n_hdlc | |
310 | * @tty - pointer to tty info structure | |
311 | * | |
312 | * Returns 0 if success, otherwise error code | |
313 | */ | |
314 | static int n_hdlc_tty_open (struct tty_struct *tty) | |
315 | { | |
316 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
317 | ||
318 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
319 | printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n", | |
320 | __FILE__,__LINE__, | |
321 | tty->name); | |
322 | ||
323 | /* There should not be an existing table for this slot. */ | |
324 | if (n_hdlc) { | |
325 | printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" ); | |
326 | return -EEXIST; | |
327 | } | |
328 | ||
329 | n_hdlc = n_hdlc_alloc(); | |
330 | if (!n_hdlc) { | |
331 | printk (KERN_ERR "n_hdlc_alloc failed\n"); | |
332 | return -ENFILE; | |
333 | } | |
334 | ||
335 | tty->disc_data = n_hdlc; | |
336 | n_hdlc->tty = tty; | |
33f0f88f | 337 | tty->receive_room = 65536; |
1da177e4 LT |
338 | |
339 | #if defined(TTY_NO_WRITE_SPLIT) | |
340 | /* change tty_io write() to not split large writes into 8K chunks */ | |
341 | set_bit(TTY_NO_WRITE_SPLIT,&tty->flags); | |
342 | #endif | |
343 | ||
344 | /* Flush any pending characters in the driver and discipline. */ | |
345 | ||
346 | if (tty->ldisc.flush_buffer) | |
347 | tty->ldisc.flush_buffer (tty); | |
348 | ||
349 | if (tty->driver->flush_buffer) | |
350 | tty->driver->flush_buffer (tty); | |
351 | ||
352 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
353 | printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__); | |
354 | ||
355 | return 0; | |
356 | ||
357 | } /* end of n_tty_hdlc_open() */ | |
358 | ||
359 | /** | |
360 | * n_hdlc_send_frames - send frames on pending send buffer list | |
361 | * @n_hdlc - pointer to ldisc instance data | |
362 | * @tty - pointer to tty instance data | |
363 | * | |
364 | * Send frames on pending send buffer list until the driver does not accept a | |
365 | * frame (busy) this function is called after adding a frame to the send buffer | |
366 | * list and by the tty wakeup callback. | |
367 | */ | |
368 | static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty) | |
369 | { | |
370 | register int actual; | |
371 | unsigned long flags; | |
372 | struct n_hdlc_buf *tbuf; | |
373 | ||
374 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
375 | printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__,__LINE__); | |
376 | check_again: | |
377 | ||
378 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
379 | if (n_hdlc->tbusy) { | |
380 | n_hdlc->woke_up = 1; | |
381 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
382 | return; | |
383 | } | |
384 | n_hdlc->tbusy = 1; | |
385 | n_hdlc->woke_up = 0; | |
386 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
387 | ||
388 | /* get current transmit buffer or get new transmit */ | |
389 | /* buffer from list of pending transmit buffers */ | |
390 | ||
391 | tbuf = n_hdlc->tbuf; | |
392 | if (!tbuf) | |
393 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
394 | ||
395 | while (tbuf) { | |
396 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
397 | printk("%s(%d)sending frame %p, count=%d\n", | |
398 | __FILE__,__LINE__,tbuf,tbuf->count); | |
399 | ||
400 | /* Send the next block of data to device */ | |
401 | tty->flags |= (1 << TTY_DO_WRITE_WAKEUP); | |
402 | actual = tty->driver->write(tty, tbuf->buf, tbuf->count); | |
403 | ||
404 | /* if transmit error, throw frame away by */ | |
405 | /* pretending it was accepted by driver */ | |
406 | if (actual < 0) | |
407 | actual = tbuf->count; | |
408 | ||
409 | if (actual == tbuf->count) { | |
410 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
411 | printk("%s(%d)frame %p completed\n", | |
412 | __FILE__,__LINE__,tbuf); | |
413 | ||
414 | /* free current transmit buffer */ | |
415 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf); | |
416 | ||
417 | /* this tx buffer is done */ | |
418 | n_hdlc->tbuf = NULL; | |
419 | ||
420 | /* wait up sleeping writers */ | |
421 | wake_up_interruptible(&tty->write_wait); | |
422 | ||
423 | /* get next pending transmit buffer */ | |
424 | tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); | |
425 | } else { | |
426 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
427 | printk("%s(%d)frame %p pending\n", | |
428 | __FILE__,__LINE__,tbuf); | |
429 | ||
430 | /* buffer not accepted by driver */ | |
431 | /* set this buffer as pending buffer */ | |
432 | n_hdlc->tbuf = tbuf; | |
433 | break; | |
434 | } | |
435 | } | |
436 | ||
437 | if (!tbuf) | |
438 | tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP); | |
439 | ||
440 | /* Clear the re-entry flag */ | |
441 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); | |
442 | n_hdlc->tbusy = 0; | |
443 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); | |
444 | ||
445 | if (n_hdlc->woke_up) | |
446 | goto check_again; | |
447 | ||
448 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
449 | printk("%s(%d)n_hdlc_send_frames() exit\n",__FILE__,__LINE__); | |
450 | ||
451 | } /* end of n_hdlc_send_frames() */ | |
452 | ||
453 | /** | |
454 | * n_hdlc_tty_wakeup - Callback for transmit wakeup | |
455 | * @tty - pointer to associated tty instance data | |
456 | * | |
457 | * Called when low level device driver can accept more send data. | |
458 | */ | |
459 | static void n_hdlc_tty_wakeup(struct tty_struct *tty) | |
460 | { | |
461 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
462 | ||
463 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
464 | printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__,__LINE__); | |
465 | ||
466 | if (!n_hdlc) | |
467 | return; | |
468 | ||
469 | if (tty != n_hdlc->tty) { | |
470 | tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP); | |
471 | return; | |
472 | } | |
473 | ||
474 | n_hdlc_send_frames (n_hdlc, tty); | |
475 | ||
476 | } /* end of n_hdlc_tty_wakeup() */ | |
477 | ||
1da177e4 LT |
478 | /** |
479 | * n_hdlc_tty_receive - Called by tty driver when receive data is available | |
480 | * @tty - pointer to tty instance data | |
481 | * @data - pointer to received data | |
482 | * @flags - pointer to flags for data | |
483 | * @count - count of received data in bytes | |
484 | * | |
485 | * Called by tty low level driver when receive data is available. Data is | |
486 | * interpreted as one HDLC frame. | |
487 | */ | |
488 | static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data, | |
489 | char *flags, int count) | |
490 | { | |
491 | register struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
492 | register struct n_hdlc_buf *buf; | |
493 | ||
494 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
495 | printk("%s(%d)n_hdlc_tty_receive() called count=%d\n", | |
496 | __FILE__,__LINE__, count); | |
497 | ||
498 | /* This can happen if stuff comes in on the backup tty */ | |
499 | if (n_hdlc == 0 || tty != n_hdlc->tty) | |
500 | return; | |
501 | ||
502 | /* verify line is using HDLC discipline */ | |
503 | if (n_hdlc->magic != HDLC_MAGIC) { | |
504 | printk("%s(%d) line not using HDLC discipline\n", | |
505 | __FILE__,__LINE__); | |
506 | return; | |
507 | } | |
508 | ||
509 | if ( count>maxframe ) { | |
510 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
511 | printk("%s(%d) rx count>maxframesize, data discarded\n", | |
512 | __FILE__,__LINE__); | |
513 | return; | |
514 | } | |
515 | ||
516 | /* get a free HDLC buffer */ | |
517 | buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); | |
518 | if (!buf) { | |
519 | /* no buffers in free list, attempt to allocate another rx buffer */ | |
520 | /* unless the maximum count has been reached */ | |
521 | if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT) | |
522 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_ATOMIC); | |
523 | } | |
524 | ||
525 | if (!buf) { | |
526 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
527 | printk("%s(%d) no more rx buffers, data discarded\n", | |
528 | __FILE__,__LINE__); | |
529 | return; | |
530 | } | |
531 | ||
532 | /* copy received data to HDLC buffer */ | |
533 | memcpy(buf->buf,data,count); | |
534 | buf->count=count; | |
535 | ||
536 | /* add HDLC buffer to list of received frames */ | |
537 | n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf); | |
538 | ||
539 | /* wake up any blocked reads and perform async signalling */ | |
540 | wake_up_interruptible (&tty->read_wait); | |
541 | if (n_hdlc->tty->fasync != NULL) | |
542 | kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN); | |
543 | ||
544 | } /* end of n_hdlc_tty_receive() */ | |
545 | ||
546 | /** | |
4a4efbde | 547 | * n_hdlc_tty_read - Called to retrieve one frame of data (if available) |
1da177e4 LT |
548 | * @tty - pointer to tty instance data |
549 | * @file - pointer to open file object | |
550 | * @buf - pointer to returned data buffer | |
551 | * @nr - size of returned data buffer | |
552 | * | |
553 | * Returns the number of bytes returned or error code. | |
554 | */ | |
555 | static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, | |
556 | __u8 __user *buf, size_t nr) | |
557 | { | |
558 | struct n_hdlc *n_hdlc = tty2n_hdlc(tty); | |
559 | int ret; | |
560 | struct n_hdlc_buf *rbuf; | |
561 | ||
562 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
563 | printk("%s(%d)n_hdlc_tty_read() called\n",__FILE__,__LINE__); | |
564 | ||
565 | /* Validate the pointers */ | |
566 | if (!n_hdlc) | |
567 | return -EIO; | |
568 | ||
569 | /* verify user access to buffer */ | |
570 | if (!access_ok(VERIFY_WRITE, buf, nr)) { | |
571 | printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user " | |
572 | "buffer\n", __FILE__, __LINE__); | |
573 | return -EFAULT; | |
574 | } | |
575 | ||
576 | for (;;) { | |
577 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) | |
578 | return -EIO; | |
579 | ||
580 | n_hdlc = tty2n_hdlc (tty); | |
581 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || | |
582 | tty != n_hdlc->tty) | |
583 | return 0; | |
584 | ||
585 | rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); | |
586 | if (rbuf) | |
587 | break; | |
588 | ||
589 | /* no data */ | |
590 | if (file->f_flags & O_NONBLOCK) | |
591 | return -EAGAIN; | |
592 | ||
593 | interruptible_sleep_on (&tty->read_wait); | |
594 | if (signal_pending(current)) | |
595 | return -EINTR; | |
596 | } | |
597 | ||
598 | if (rbuf->count > nr) | |
599 | /* frame too large for caller's buffer (discard frame) */ | |
600 | ret = -EOVERFLOW; | |
601 | else { | |
602 | /* Copy the data to the caller's buffer */ | |
603 | if (copy_to_user(buf, rbuf->buf, rbuf->count)) | |
604 | ret = -EFAULT; | |
605 | else | |
606 | ret = rbuf->count; | |
607 | } | |
608 | ||
609 | /* return HDLC buffer to free list unless the free list */ | |
610 | /* count has exceeded the default value, in which case the */ | |
611 | /* buffer is freed back to the OS to conserve memory */ | |
612 | if (n_hdlc->rx_free_buf_list.count > DEFAULT_RX_BUF_COUNT) | |
613 | kfree(rbuf); | |
614 | else | |
615 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,rbuf); | |
616 | ||
617 | return ret; | |
618 | ||
619 | } /* end of n_hdlc_tty_read() */ | |
620 | ||
621 | /** | |
622 | * n_hdlc_tty_write - write a single frame of data to device | |
623 | * @tty - pointer to associated tty device instance data | |
624 | * @file - pointer to file object data | |
625 | * @data - pointer to transmit data (one frame) | |
626 | * @count - size of transmit frame in bytes | |
627 | * | |
628 | * Returns the number of bytes written (or error code). | |
629 | */ | |
630 | static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, | |
631 | const unsigned char *data, size_t count) | |
632 | { | |
633 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
634 | int error = 0; | |
635 | DECLARE_WAITQUEUE(wait, current); | |
636 | struct n_hdlc_buf *tbuf; | |
637 | ||
638 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
639 | printk("%s(%d)n_hdlc_tty_write() called count=%Zd\n", | |
640 | __FILE__,__LINE__,count); | |
641 | ||
642 | /* Verify pointers */ | |
643 | if (!n_hdlc) | |
644 | return -EIO; | |
645 | ||
646 | if (n_hdlc->magic != HDLC_MAGIC) | |
647 | return -EIO; | |
648 | ||
649 | /* verify frame size */ | |
650 | if (count > maxframe ) { | |
651 | if (debuglevel & DEBUG_LEVEL_INFO) | |
652 | printk (KERN_WARNING | |
653 | "n_hdlc_tty_write: truncating user packet " | |
654 | "from %lu to %d\n", (unsigned long) count, | |
655 | maxframe ); | |
656 | count = maxframe; | |
657 | } | |
658 | ||
659 | add_wait_queue(&tty->write_wait, &wait); | |
660 | set_current_state(TASK_INTERRUPTIBLE); | |
661 | ||
662 | /* Allocate transmit buffer */ | |
663 | /* sleep until transmit buffer available */ | |
664 | while (!(tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list))) { | |
665 | schedule(); | |
666 | ||
667 | n_hdlc = tty2n_hdlc (tty); | |
668 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || | |
669 | tty != n_hdlc->tty) { | |
670 | printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc); | |
671 | error = -EIO; | |
672 | break; | |
673 | } | |
674 | ||
675 | if (signal_pending(current)) { | |
676 | error = -EINTR; | |
677 | break; | |
678 | } | |
679 | } | |
680 | ||
681 | set_current_state(TASK_RUNNING); | |
682 | remove_wait_queue(&tty->write_wait, &wait); | |
683 | ||
684 | if (!error) { | |
685 | /* Retrieve the user's buffer */ | |
686 | memcpy(tbuf->buf, data, count); | |
687 | ||
688 | /* Send the data */ | |
689 | tbuf->count = error = count; | |
690 | n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf); | |
691 | n_hdlc_send_frames(n_hdlc,tty); | |
692 | } | |
693 | ||
694 | return error; | |
695 | ||
696 | } /* end of n_hdlc_tty_write() */ | |
697 | ||
698 | /** | |
699 | * n_hdlc_tty_ioctl - process IOCTL system call for the tty device. | |
700 | * @tty - pointer to tty instance data | |
701 | * @file - pointer to open file object for device | |
702 | * @cmd - IOCTL command code | |
703 | * @arg - argument for IOCTL call (cmd dependent) | |
704 | * | |
705 | * Returns command dependent result. | |
706 | */ | |
707 | static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, | |
708 | unsigned int cmd, unsigned long arg) | |
709 | { | |
710 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
711 | int error = 0; | |
712 | int count; | |
713 | unsigned long flags; | |
714 | ||
715 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
716 | printk("%s(%d)n_hdlc_tty_ioctl() called %d\n", | |
717 | __FILE__,__LINE__,cmd); | |
718 | ||
719 | /* Verify the status of the device */ | |
720 | if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC) | |
721 | return -EBADF; | |
722 | ||
723 | switch (cmd) { | |
724 | case FIONREAD: | |
725 | /* report count of read data available */ | |
726 | /* in next available frame (if any) */ | |
727 | spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock,flags); | |
728 | if (n_hdlc->rx_buf_list.head) | |
729 | count = n_hdlc->rx_buf_list.head->count; | |
730 | else | |
731 | count = 0; | |
732 | spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags); | |
733 | error = put_user(count, (int __user *)arg); | |
734 | break; | |
735 | ||
736 | case TIOCOUTQ: | |
737 | /* get the pending tx byte count in the driver */ | |
738 | count = tty->driver->chars_in_buffer ? | |
739 | tty->driver->chars_in_buffer(tty) : 0; | |
740 | /* add size of next output frame in queue */ | |
741 | spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags); | |
742 | if (n_hdlc->tx_buf_list.head) | |
743 | count += n_hdlc->tx_buf_list.head->count; | |
744 | spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock,flags); | |
745 | error = put_user(count, (int __user *)arg); | |
746 | break; | |
747 | ||
748 | default: | |
749 | error = n_tty_ioctl (tty, file, cmd, arg); | |
750 | break; | |
751 | } | |
752 | return error; | |
753 | ||
754 | } /* end of n_hdlc_tty_ioctl() */ | |
755 | ||
756 | /** | |
757 | * n_hdlc_tty_poll - TTY callback for poll system call | |
758 | * @tty - pointer to tty instance data | |
759 | * @filp - pointer to open file object for device | |
760 | * @poll_table - wait queue for operations | |
761 | * | |
762 | * Determine which operations (read/write) will not block and return info | |
763 | * to caller. | |
764 | * Returns a bit mask containing info on which ops will not block. | |
765 | */ | |
766 | static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, | |
767 | poll_table *wait) | |
768 | { | |
769 | struct n_hdlc *n_hdlc = tty2n_hdlc (tty); | |
770 | unsigned int mask = 0; | |
771 | ||
772 | if (debuglevel >= DEBUG_LEVEL_INFO) | |
773 | printk("%s(%d)n_hdlc_tty_poll() called\n",__FILE__,__LINE__); | |
774 | ||
775 | if (n_hdlc && n_hdlc->magic == HDLC_MAGIC && tty == n_hdlc->tty) { | |
776 | /* queue current process into any wait queue that */ | |
777 | /* may awaken in the future (read and write) */ | |
778 | ||
779 | poll_wait(filp, &tty->read_wait, wait); | |
780 | poll_wait(filp, &tty->write_wait, wait); | |
781 | ||
782 | /* set bits for operations that won't block */ | |
783 | if(n_hdlc->rx_buf_list.head) | |
784 | mask |= POLLIN | POLLRDNORM; /* readable */ | |
785 | if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) | |
786 | mask |= POLLHUP; | |
787 | if(tty_hung_up_p(filp)) | |
788 | mask |= POLLHUP; | |
789 | if(n_hdlc->tx_free_buf_list.head) | |
790 | mask |= POLLOUT | POLLWRNORM; /* writable */ | |
791 | } | |
792 | return mask; | |
793 | } /* end of n_hdlc_tty_poll() */ | |
794 | ||
795 | /** | |
796 | * n_hdlc_alloc - allocate an n_hdlc instance data structure | |
797 | * | |
798 | * Returns a pointer to newly created structure if success, otherwise %NULL | |
799 | */ | |
800 | static struct n_hdlc *n_hdlc_alloc(void) | |
801 | { | |
802 | struct n_hdlc_buf *buf; | |
803 | int i; | |
804 | struct n_hdlc *n_hdlc = kmalloc(sizeof(*n_hdlc), GFP_KERNEL); | |
805 | ||
806 | if (!n_hdlc) | |
807 | return NULL; | |
808 | ||
809 | memset(n_hdlc, 0, sizeof(*n_hdlc)); | |
810 | ||
811 | n_hdlc_buf_list_init(&n_hdlc->rx_free_buf_list); | |
812 | n_hdlc_buf_list_init(&n_hdlc->tx_free_buf_list); | |
813 | n_hdlc_buf_list_init(&n_hdlc->rx_buf_list); | |
814 | n_hdlc_buf_list_init(&n_hdlc->tx_buf_list); | |
815 | ||
816 | /* allocate free rx buffer list */ | |
817 | for(i=0;i<DEFAULT_RX_BUF_COUNT;i++) { | |
818 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); | |
819 | if (buf) | |
820 | n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,buf); | |
821 | else if (debuglevel >= DEBUG_LEVEL_INFO) | |
822 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for rx buffer %d\n",__FILE__,__LINE__, i); | |
823 | } | |
824 | ||
825 | /* allocate free tx buffer list */ | |
826 | for(i=0;i<DEFAULT_TX_BUF_COUNT;i++) { | |
827 | buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); | |
828 | if (buf) | |
829 | n_hdlc_buf_put(&n_hdlc->tx_free_buf_list,buf); | |
830 | else if (debuglevel >= DEBUG_LEVEL_INFO) | |
831 | printk("%s(%d)n_hdlc_alloc(), kalloc() failed for tx buffer %d\n",__FILE__,__LINE__, i); | |
832 | } | |
833 | ||
834 | /* Initialize the control block */ | |
835 | n_hdlc->magic = HDLC_MAGIC; | |
836 | n_hdlc->flags = 0; | |
837 | ||
838 | return n_hdlc; | |
839 | ||
840 | } /* end of n_hdlc_alloc() */ | |
841 | ||
842 | /** | |
843 | * n_hdlc_buf_list_init - initialize specified HDLC buffer list | |
844 | * @list - pointer to buffer list | |
845 | */ | |
846 | static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list) | |
847 | { | |
848 | memset(list, 0, sizeof(*list)); | |
849 | spin_lock_init(&list->spinlock); | |
850 | } /* end of n_hdlc_buf_list_init() */ | |
851 | ||
852 | /** | |
853 | * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list | |
854 | * @list - pointer to buffer list | |
855 | * @buf - pointer to buffer | |
856 | */ | |
857 | static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, | |
858 | struct n_hdlc_buf *buf) | |
859 | { | |
860 | unsigned long flags; | |
861 | spin_lock_irqsave(&list->spinlock,flags); | |
862 | ||
863 | buf->link=NULL; | |
864 | if(list->tail) | |
865 | list->tail->link = buf; | |
866 | else | |
867 | list->head = buf; | |
868 | list->tail = buf; | |
869 | (list->count)++; | |
870 | ||
871 | spin_unlock_irqrestore(&list->spinlock,flags); | |
872 | ||
873 | } /* end of n_hdlc_buf_put() */ | |
874 | ||
875 | /** | |
876 | * n_hdlc_buf_get - remove and return an HDLC buffer from list | |
877 | * @list - pointer to HDLC buffer list | |
878 | * | |
879 | * Remove and return an HDLC buffer from the head of the specified HDLC buffer | |
880 | * list. | |
881 | * Returns a pointer to HDLC buffer if available, otherwise %NULL. | |
882 | */ | |
883 | static struct n_hdlc_buf* n_hdlc_buf_get(struct n_hdlc_buf_list *list) | |
884 | { | |
885 | unsigned long flags; | |
886 | struct n_hdlc_buf *buf; | |
887 | spin_lock_irqsave(&list->spinlock,flags); | |
888 | ||
889 | buf = list->head; | |
890 | if (buf) { | |
891 | list->head = buf->link; | |
892 | (list->count)--; | |
893 | } | |
894 | if (!list->head) | |
895 | list->tail = NULL; | |
896 | ||
897 | spin_unlock_irqrestore(&list->spinlock,flags); | |
898 | return buf; | |
899 | ||
900 | } /* end of n_hdlc_buf_get() */ | |
901 | ||
902 | static char hdlc_banner[] __initdata = | |
903 | KERN_INFO "HDLC line discipline: version " HDLC_VERSION | |
904 | ", maxframe=%u\n"; | |
905 | static char hdlc_register_ok[] __initdata = | |
906 | KERN_INFO "N_HDLC line discipline registered.\n"; | |
907 | static char hdlc_register_fail[] __initdata = | |
908 | KERN_ERR "error registering line discipline: %d\n"; | |
909 | static char hdlc_init_fail[] __initdata = | |
910 | KERN_INFO "N_HDLC: init failure %d\n"; | |
911 | ||
912 | static int __init n_hdlc_init(void) | |
913 | { | |
914 | int status; | |
915 | ||
916 | /* range check maxframe arg */ | |
917 | if (maxframe < 4096) | |
918 | maxframe = 4096; | |
919 | else if (maxframe > 65535) | |
920 | maxframe = 65535; | |
921 | ||
922 | printk(hdlc_banner, maxframe); | |
923 | ||
924 | status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc); | |
925 | if (!status) | |
926 | printk(hdlc_register_ok); | |
927 | else | |
928 | printk(hdlc_register_fail, status); | |
929 | ||
930 | if (status) | |
931 | printk(hdlc_init_fail, status); | |
932 | return status; | |
933 | ||
934 | } /* end of init_module() */ | |
935 | ||
936 | static char hdlc_unregister_ok[] __exitdata = | |
937 | KERN_INFO "N_HDLC: line discipline unregistered\n"; | |
938 | static char hdlc_unregister_fail[] __exitdata = | |
939 | KERN_ERR "N_HDLC: can't unregister line discipline (err = %d)\n"; | |
940 | ||
941 | static void __exit n_hdlc_exit(void) | |
942 | { | |
943 | /* Release tty registration of line discipline */ | |
64ccd715 | 944 | int status = tty_unregister_ldisc(N_HDLC); |
1da177e4 LT |
945 | |
946 | if (status) | |
947 | printk(hdlc_unregister_fail, status); | |
948 | else | |
949 | printk(hdlc_unregister_ok); | |
950 | } | |
951 | ||
952 | module_init(n_hdlc_init); | |
953 | module_exit(n_hdlc_exit); | |
954 | ||
955 | MODULE_LICENSE("GPL"); | |
956 | MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com"); | |
957 | module_param(debuglevel, int, 0); | |
958 | module_param(maxframe, int, 0); | |
959 | MODULE_ALIAS_LDISC(N_HDLC); |